SPIRAL DIVE TEST

Published by: Larry Mednick on 15th Nov 2012 | View all blogs by Larry Mednick
Please take a moment and take the TEST below

If you do not normally post, it's time to log in and give your answer. If your not sure if you know the correct answer then PLEASE make SURE you give your answer because my point is I believe a considerable percentage of pilots will get this wrong. I do ask that our Veteran trike pilots do not answer until last as we don't want any "cheating" :-)

Please EVERYONE LOG ON AND POST YOUR ANSWER 

SCENARIO:  You are banked 60 degrees to the right and descending at 2000FPM at roughly cruise throttle setting at roughly cruise speed.

How do you stop the descent?

pick 1 or more answers from below and put into order

  •           A) Push the control bar forward
              B) Pull the control bar in 
              C) Move the control bar to the right
              D) Move the control bar to the left 
              E) Go to full throttle
              F)  Go to idle
     
    Thanks for participating in advance,

    Larry Mednick

     

Comments

125 Comments

  • Jim Waters
    by Jim Waters 5 years ago
    f,c,a
  • Rizwan Bukhari
    by Rizwan Bukhari 5 years ago
    f,c,b ? if you are locked in, I am thinking you have some forward pressure on the bar that is why I picked b
  • Kael Rowan
    by Kael Rowan 5 years ago
    F, C, and then after you've stopped banking then start A but not so much that you stall or break the wing. I think the goal would be to level out while keeping speeds and forces just under their maximum. Hopefully you have enough altitude to do so.

    I'm not sure what Riz means but I can imagine that if you level out horizontally but still have excessive speed then you'll need to hold the bar in (or turn) to avoid launching up in a steep climb from all the excessive speed.
  • Wesley Frey
    by Wesley Frey 5 years ago
    F B C. Wait a while then allow A
  • Larry  Mednick
    by Larry Mednick 5 years ago
    BTW to clarify this topic, it is my opinion that this scenario should be avoided all together. But on the other hand trikes are brought to this scenario usually unintentionally and the question remains how do you fix it? Because if you don't fix it one of two things will happen. One: you will get too fast and possibly break your wing or two the ground will eventually stop you. So the question is do you know how to stop the spiral most effectively.
  • Jan Ferreira
    by Jan Ferreira 5 years ago
    Wes, you are a cheat..:>) you are an experienced pilot and should have waited with the correct answer...:>)
  • John Young
    by John Young 5 years ago
    Larry - nice talking just now. But more important, how do you avoid getting into a 60 degree bank descending at 2000fpm? This is another serious learning point. Rather than me, you as an instructor explain what the pilot has not done to allow this very, very dangerous scenario to develop.
  • John Olson
    by John Olson 5 years ago
    Shove the wing level.
  • Kael Rowan
    by Kael Rowan 5 years ago
    Why pull in? If you're at cruise speed plus a descent of 22mph then you already have more that enough speed don't you? I could see pulling in if you're already at idle (w/ low speed) and suddenly end up in a 60 deg bank, but why if you're at cruise + 22mph vertically down?
  • John Young
    by John Young 5 years ago
    Kael - think about all the factors in a steep spiral dive. Why is it spiral?

    John - don't forget the extra forces on the outside wing in an overspeed spiral situation. More action is required.
  • Larry  Mednick
    by Larry Mednick 5 years ago
    John Young, you avoid such an aggressive spiral the same way you get out of an aggressive spiral. Doing the wrong things or the correct steps out of order can further the situation into an even more aggressive spiral.
  • John Young
    by John Young 5 years ago
    Larry - I hear you. The cause is allowing the nose to drop sharply when entering steep turn. This would be an uncoordinated turn where the pilot just inputs steep bank. This is the learning point - only conduct properly coordinated turns.
  • Kael Rowan
    by Kael Rowan 5 years ago
    From the description it doesn't seem like the trike is in a spiral *yet*, but if someone started pushing the bar *out* without leveling the wing to try to prevent the descent then yes, I can see why you'd want to pull in, to stop/prevent the spiral from getting tighter. But I don't know why you wouldn't have focused on leveling the wing first instead, preventing the tight spiral in the first place.
  • John Young
    by John Young 5 years ago
    Kael - you forgetting the serious overspeed factor. A high-performance Revo could reach way over 130mph. The extra "lift" at this speed will force the spiral. Add bar out to reduce the decent and it is good night nurse. This is why so many pilots have died RIP. They didn't know how they got into the spiral and they didn't know how to get out.
  • B  Alvarius
    by B Alvarius 5 years ago
    A visual answer
    http://www.trikepilot.com/videos/view/the-importance-of-missing_9391.html?m=31
    Hit the mute button if you do not like machine guns.
  • jeff trike
    by jeff trike 5 years ago
    C
    center the control bar without moving it back or forth,
    when you come out of the turn, you'll probably have to adjust the control bar forwards/backward to set the vertical speed to zero.

    I do this all the time to drop altitude in a hurry, the main thing is to not
    make any sudden movements on the control bar in any direction.
  • Rizwan Bukhari
    by Rizwan Bukhari 5 years ago
    Larry, there is one option missing

    g) Deploy the BRS :)
  • Rizwan Bukhari
    by Rizwan Bukhari 5 years ago
    Kael, I wanted to say to keep the bar neutral or slightly pull it in to prevent from the trike wanting to climb from all that excessive speed. Jeff's answer is a better, either move the bar forward or backward to set the vertical speed to zero.
  • Kael Rowan
    by Kael Rowan 5 years ago
    I'm not forgetting the overspeed factor, in fact that's the whole reason I wanted to get clarification on why one would recommend pulling the bar in when already dealing with more than enough speed. It sounds like the the answer is to pull in if 1) you were erroneously pushing it out prior or 2) if the sheer speed is pushing it out for you (due to the extra inward-pointed lift generated if you've already accelerated to a high rate of speed) and you need to counteract that force.
  • Kael Rowan
    by Kael Rowan 5 years ago
    Thanks Riz. By the way, by "inward-pointed lift" I mean to point out for novice pilots that the lift in this case is pointing diagonally towards the center of the spiral - causing the spiral to become sharper and tighter - just in case a novice might see the word "lift" and automatically assume its always a force lifting the trike directly up vertically away from the earth.
  • Rizwan Bukhari
    by Rizwan Bukhari 5 years ago
    You are welcome Kael, to tell you the truth, I am not the right person to answer any questions on advance manuvers, I am a 100 hour pilot who still doesn't like doing steep turns...LOL, I have never done Spirals. Next year, I plan to get with an Instructor to get my comfort level up with advance skills. I mean if I have to do them I will but it's just getting comfortable with it....Not quite there yet.
  • Vince  Morson
    by Vince Morson 5 years ago
    I'd go with f,c b too- and looking forward to a well explained answer
  • Captain X
    by Captain X 5 years ago
    I'm going to delete mine for now-- Larry still has a record of it though so he can call me on it if it was not the answer he was thinking of. Great subject & format Larry, great to have you here again!
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    I would venture an answer, but I don't want to look foolish.

    When I flew with Larry in his Blue Devil last winter, I had the controls and was relishing a right-hand 60+ degree bank (unlike Rizwan, I love steep turns, plus, in this context I was being relatively reckless because I knew Larry could save me from myself). As I kept inching steeper, the nose would try harder to drop, and I'd push the bar out more to compensate -- overall, doing fine in maintaining a level if increasingly tight turn. That was until, suddenly, the roll increased violently on its own accord. I still haven't discussed this in-depth with Larry, but I believe the lower wing must have stalled. With the upper wing still flying and the lower one not, the inevitable consequence was extremely rapid inducement of increased rightward roll. With us already at well over 60 degrees right, this was not a good thing. Doing his job, Larry instantly took the controls and saved us (absent his correction, I believe we'd have been inverted in much less than a second). I do not know precisely what he did, and have been anxious to fly with him again to have him teach me.

    This is not the same as the scenario on which Larry has here inquired, but I think might be of interest in this discussion as well.
  • Paul Hamilton
    by Paul Hamilton 5 years ago
    Great post Larry. As you request, I will keep quiet since I love spirals. Please everyone provide your input and ideas/thoughts to help make this a learning experience for all.
  • Mark Crabb
    by Mark Crabb 5 years ago
    My answer would be: F, C, B, A. Slow your decent, negate the spiral, re-establish lift, establish level flight.
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Hey Larry ... nice to "hear" you writing :-) ... your description sounds like our normal right hand turn down to final ;-) ... I guess you just level and land ja ja ... ok kidding ;-)
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    Tony, it sounds like you may like to land like me (and I hope like heck it's not dangerous; I don't feel that it is, but I am ready for correction from those more experienced).

    I like to do a very tight pattern. I fly the downwind at maybe 500' AGL, and cut to idle at about 150 yards past parallel to the runway threshold. I maintain the downwind at glide for about 150 further yards, then transition to a turning-base-into-final dive (in other words, it's a tight 180 turn to final with the nose pointed downward). This rapidly kills my excess altitude, and accelerates to a speed that I feel makes me very safe to negotiate any wind gradient nearer the ground. It's also challenging, fun and quick. I am generally to 5' AGL about 75 yards before the runway threshold, and maintain float to touchdown at about 25 yards post threshold (with obvious variance from instance to instance).

    It's a tight maneuver, and, as pilot, it's my impression I am being very safe in its execution (though I'll grant that an uninitiated passenger could easily feel intimidated).

    Regardless, this discussion about out-of-control spiral dives makes me worried as to whether I may be inadvertently courting such. I do not remember going over spiral dives (at least as potential loss-of-control situations) in my training. For such reason, I am very interested in learning via this discussion more about how a pilot inadvertently gets into one, and then gets out.
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    If any of you are wondering, the above is not the approach Clyde taught me. I just kept practicing and practicing, with my pattern getting tighter and tighter. It simply evolved to what I above describe. I mentioned on another blog that I recently decided to count how many cycles I'd make it through in an hour. I counted to 42.
  • Rizwan Bukhari
    by Rizwan Bukhari 5 years ago
    You (or at least your family) gets out of a Spiral dive by having a good life insurance...LOL
  • Joe Derrick
    by Joe Derrick 5 years ago
    I haven't read the other posts yet, giving my answer first. 'C'
    Great topic as I have 64 hrs logged, this is good stuff for all.
  • Abid Farooqui
    by Abid Farooqui 5 years ago
    Brits came up with nice acronyms of positive attitude control that are easy to remember for new pilots and students.

    PAT into a climb
    APT to level (and especially to initiate a descent, never allow to drop the nose much and establishing descent or leveling out should not be lead with Power)

    P = Power (adjust)
    A = Attitude
    T = Trim (stabilize)

    AOA = Angle Of Attack
    AOB = Angle Of Bank

    Paul Dewhurst was not very happy that Trike Flying Handbook did not emphasize these clearly in the book. Leaving room for interpretation.
    Well, if you understand things and concepts you don't need to rote learn acronyms but it does seem like understanding is harder to come by than it seems to some of us.

    In level flight we climb without wing lift being more than in level or descending flight. In fact, to be technical wing lift is usually "less" in climb. We are using power to overcome "drag". Power isn't creating any extra lift. Its simply overcoming drag due to upwards angled path. This drag is created by gravity's adamant opposition to our attempt to get further away from her grip at an uphill angle.

    For turning flight, there are some fundamental differences. Bank angle reduces the vertical component of wing lift as lift is perpendicular to the chord plane of the wing and that loss of vertical component of lift must be replaced if descending flight isn't desired. This can only be done by one of the following:
    1) increasing AOA or
    2) if we remain at the same AOA, increasing the airspeed

    Now imagine what airspeed you would need to increase to keep level turn at 60 degrees of bank? Just think about what your stall speed is at 60 degrees AOB.

    When you are in a coordinated turn (pretty much any turn in a trike after the first second or two) the G force increases by the inverted cosine of AOB. Cosine of 60 degrees is 0.5. G loading is inverse of cosine of the bank angle. Simply put 1/Cos 60 = 1/0.5 = 2 G's. Simply take level stall speed Vso and multiply it by square root of this load factor. In short, Vso x sq.rt(1/Cos AOB) = Vso x sq.rt (2) = 1.41 Vso for 60 degrees AOB
    You can see for 70 degrees AOB then the stall speed is Vso x sq.rt(1/Cos 70) = 1.7 Vso
    At 80 degrees AOB then the stall speed is Vso x sq.rt(1/Cos 80) = 2.4 Vso
    You can start to see that with higher AOB you are quickly to run out of "more speed" to avoid a stall and the only practical solution left is AOA. In fact, the lady at Winter Haven accident was probably stalled at 85 mph at steep bank angle coming right down to the ground but which new pilot thinks they will be at 85 mph and stalled. Well stop thinking speed, start thinking AOA.
    The only time, speed is a good indicator of AOA is when your wings are level (or at 1 G to be more pedantic)

    The only thing that can increase angle of attack is bar movement. Therefore lift is being increased to maintain level flight by the pitch control - not the power in turning flight. Power is simply overcoming the increase in "induced drag" that's more prevalent at higher AOA

    Once you are locked in a spiral dive however, you have already made the above mistake. You were too late, you had stalled. After the stall the nose drops (yes even in a turning stall it does ... no don't try 60 degrees AOB and then a stall at home folks, leave that to test pilots please), that then creates high descent rate. Now you want to push the bar out by instinct but remember you already stalled the darn thing because you were behind the curve ball. Stall means you are at or beyond critical AOA. You need to "decrease the angle of attack". You need to not lead by power because sudden application of power will accelerate the descent at first. You need to decrease AOA while leveling the wing in quick succession in that order (these may seem almost happening at same time but your roll is not effective till you are below critical AOA) -- now that you have attitude (A) under control, you can apply Power (P) and smoothly level as necessary adjusting power and adjusting bar to neutral (Trim T).

    There is little emphasis on specific ground school in trike circles in the US. We need to up the game if we are serious. Conceptual understanding breeds confidence in technique that will save your behind when you get yourself into an unusual attitude. Its all fun and games and easy while its all fun and games and well easy. You just don't know when that student in the front is going to lock his arms on you at 200 feet AGL. Then, well then its not all fun and games.
  • Brian Reynolds
    by Brian Reynolds 5 years ago
    Larry thanks for clarifying. I'm glad to see some pilots are wondering how and why anyone would do this maneuver. I guess if a pilot has really screwed up and got themselves into this situation their CFI and DPE shouldn't have signed them off. This is damn reckless.
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    After thinking if over this morning before coming to work, I was going to offer F, C then A (upon looking now I see that's the same as was first answered by Jim). However, upon reading Abid's comments I think the better answer is likely B then C.

    Thanks, Larry, for posing a great question. I am anxious for the official answer. I also feel determined to get direct training in this. I'd like to know exactly how to react, and practice until it becomes muscle memory.
  • Captain X
    by Captain X 5 years ago
    I noticed the recommendation against spiral dive as an avoidance maneuver was edited out.
  • Ken Nussear
    by Ken Nussear 5 years ago
    I'll weigh in with a simultaneous B and C, then A to level out
  • Larry  Mednick
    by Larry Mednick 5 years ago
    Ole I assume your answer is C
    Abid, I assume your answer is FBC
    Glade your answers are FCA and FBC
    David O I assume your private answer to me was FBC

    More answers guys. lets get the general consensus. we need all of you to post.
  • Brian Reynolds
    by Brian Reynolds 5 years ago
    F, some B and a little C
  • Larry  Mednick
    by Larry Mednick 5 years ago
    On the discussion, I do not believe it is difficult to enter a spiral on accident at all. Sure over banking is a sure fire way to enter a spiral. also tightening up a steep turn until stall is another. Pushing out too late and not "coordinating" the turn is another. Also holding the bar forward during a stall and continuing to hold forward while the nose is dropping is another. or simply entering a spiral on purpose and not being able to get out of it. These are all ways into the above scenario of 60 degrees in bank falling 2000 FPM.

    It happens, it will continue to happen and only knowing how to instantly get out of a spiral ensures your safety.
  • Larry  Mednick
    by Larry Mednick 5 years ago
    Remember to stop a descent with wings level is full throttle and push forward. Is it really any different in a spiral?

    Post your answers does anyone think the answer is E A C ?

    it's not in the text books. I don't believe you can look up the answer....
  • Abid Farooqui
    by Abid Farooqui 5 years ago
    Yeah (F)BC works. Though generally locked in a spiral means they are already at idle but not always so B and C would be ok in that case. It gets followed by A later on but you are out of the spiral at that point and you are only concerned with getting out of it, it seems.
    Drove 200 miles towards TN for vacation last night with family, just to find that my wife started getting bad fever and sick and had to turn around and return so was quite out of it when I wrote that last night. Sorry didn't see the "don't answer" early for higher time pilots. This is such a simple and basic thing, no one should ever be getting locked into spirals in the first place and if so, they should be able to get out of them as a non-issue within seconds. Trikes have one of the mildest stalls of any winged category of aircraft. This should never be an issue in a trike. You'd go towards a spin and unchecked for a few seconds it would get into a flat spin if you did this in most airplanes and its very difficult to get out of flat spins. I just wrote 8 flight test data cards to perform 8 different spin tests on an airplane. Trikes are "easy" comparatively.
  • Abid Farooqui
    by Abid Farooqui 5 years ago
    Some places outside US do have these answers:
    http://www.start-flying.com/new%20site/how_fly_micro.htm#Get out of a spiral dive
    He emphasizes not to try to reduce speed first but level the wings but I would say, to be safe reduce AOA slightly (slightly pull in as counter-intuitive as it is) and turn the wing level almost simultaneously to get out. Definitely don't push-out and definitely don't get power involved (torque can generate its own demons).

    Aerial Pursuits website has similar answer
    http://www.aerialpursuits.com/trikes/faqtech.htm
    Search for High Speed Spiral Dives around mid page


    Most importantly however, the accident aircraft in this case "Northwing Apache" POH which I am sure like most POH and MIP's people don't read has the following information in it including a warning not to go into spiral dives of high bank

    3.9. Spins and Spiral Descending turns
    Deliberate spins and severe spiral turns are prohibited in this aircraft. A spin is a difficult
    situation to get into. Flex wings resist spins and you would have to physically hold the trike
    wing into a spin. Spins can happen when you stall at a low speed and high angle of attack
    (AOA). If a turn is then induced and you continue to hold the bar forward (nose up), the trike
    will spin. To get out of a spin release the backpressure on the control bar to allow the nose to
    lower and recover from being stalled. Manage speed and AOA as you exit the spin.
    Mild descending turns (45 degrees of bank or less) at less then Vne can be used to reduce
    altitude.
    Fast spirals over 45 degrees of bank and above Vne could result in being locked in a turn unable
    to roll out, a non-recoverable situation resulting in impact with the ground. If you find yourself
    in a spiral dive and feel you can still recover you must try to roll out of the turn and then pull out
    of the dive very gradually to avoid rapid pitch up and structural damage or failure to the aircraft.
    A rapid pitch up from Vne can cause loads that exceed the design limits of the wing
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    My true guess did not include F (F was only in what I flirted with before reading Abid's initial analysis). My true/submitted guess was BC. I was about to reaffirm that, but, Larry, your most recent post makes me reconsider. For the reason you mention, I believe full throttle (E) might indeed make sense. I think you might be deliberately misleading, however, in regard to A. If the spiral dive involves one wing being stalled (as I believe Abid suggests), A would simply make that worse. So, until the stall on that wing is overcome, I think B makes much better sense than A. Thus, I modify my answer from BC to EBC.

    BTW, the above was typed (though it's now slightly altered) before I saw Abid's two most recent posts. Even having now read those, I believe I'll stick with EBC.
  • jeff trike
    by jeff trike 5 years ago
    In a spiral dive, you will have plenty of speed. It is easy to get to VNE in this mode.
    The fastest airspeed I have ever flow in was in a controlled spiral dive.
    You are not stalled. This is not a spin either. But your are dropping and turning fast.

    There is no need to pull in for extra speed, and you don't want to push out cause this will put huge loads on the wing, and possibly cause a stall. Get the wing rolled level first with excess speed, your decent rate will slow or stop and you will probably climb. At this point you can adjust throttle and pitch position to level out.

    Don't mess with the throttle, its already set for cruise. That's where you want it to be when you are done.

    C is all you need to do.
  • Brian Reynolds
    by Brian Reynolds 5 years ago
    Larry, at what altitude does your scenario take place. Does it make a difference on what is done on how close to the ground you are? My previous answer is if I have lots of altitude to recover. I think you are screwed anything below 400-500 ft with the throttle on cruise in a spiral as described. I agree with Abid. This should never happen unless you weren't taught well by an instructor. I agree this will happen with pilots that have a tendency to do what ever they want because someone says its possible or some other pilot says "I've done this lots of times".
  • Jan Ferreira
    by Jan Ferreira 5 years ago
    Larry,
    You are screwing with our minds..:>) I don't think there is one correct answer; I think there is more than one answer that can be correct. If you go full throttle and push out you will go into a hard turn but not stall, that will give you time to straighten the bar and get out of trouble. ( as long as the ground isn't in your way) and you don't break the wing with too much stress. On the other hand if you go to idle and pull the bar in you will also increase speed and not stall and have time to straighten out. In my opinion both methods will get you out of trouble if the ground does not come in the way. The main objective is not to have one side stall but keep both sides flying, then you can fly out of trouble as long as you do not exceed the stress the wing can handle.
  • reb wallace
    by reb wallace 5 years ago
    well my 2 cents worth, for one there isn't enough info to come up with exact answer, example is what type of wing and size, ex. double or single surface, DA. and of course wind cond. however from experience with a north wing 15 mustang series wing we cant't get it to drop at 2000 fpm without being in a mother of all sinks, even in a spiral dive, it simply won't dive at that rate on its own, however in about the 3rd spiral at 60 degrees bank it becomes very difficult to move the control bar side to side but you can push it out so thats the first thing A push out, then level the wing, and with that kind of sink rate you better add power, as much as needed to get out of sink. other factors would change that scenario in other words a double surface fast wing could reach a much faster sink rate, so the answer would change. Larry has a lot of experience with those faster wings so will let him decide that answer.
  • Kael Rowan
    by Kael Rowan 5 years ago
    Wow I'm surprised to see the shift in answers here. I may be just as wrong as anyone else but the fact that so many pilots are giving different answers (and/or changing their answers as the thread goes on) undoubtedly indicates that there indeed a serious lack of knowledge/training on this topic! It makes me want to go to 10,000' and get some serious practice with this (with my instructor and my trusty BRS in the back seat of course).
  • Brian Reynolds
    by Brian Reynolds 5 years ago
    Yup only people that have done this might be able to give us direction depending on the wing and weight. God forbid someone is with you when this happens. Hey Reb if you push out too fast can you induce a tumble? I'm thinking if a pilot has gotten themselves into this situation they have already made a big mistake and most low time pilots will panic and once that happens its over. I keep saying don't get yourself into this situation. Some pilots chose to do maneuvers even the manufacturers say not to do. These are not hang gliders. How many of us have gotten into this situation unintentionally? Not I. If you screw around too long trying to recover you may not be able to deploy your BRS properly.
  • Douglas Donaldson
    by Douglas Donaldson 5 years ago
    Reb - I'm interested by your experience with the Mustang 15 becoming very difficult to roll with lateral bar movement "at about the third spiral at 60 degrees bank". I wonder if this is typical of trike wings. I wonder what is different at the third spiral (airspeed? rate of turn? coordination? loading?) How close to Vne are you after three spirals? What makes a wing "refuse" to roll?

    I'm thinking ...
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    Kael, I certainly agree with you. It's possible Larry has exposed a hole in widespread knowledge that's responsible for at least some among the recent spate of fatalities. Personally, I don't remember prior even having had an inclination that a spiral dive is something to worry about. I was trying to remember if I'd read anything concerning it in the FAA's Weight Shift Control Handbook (which I've read cover-to-cover thoroughly twice, and less thoroughly more times). I clearly remember reading about the tuck and tumble hazard (and I've been very conscious of same), but not about spiral dives. Curious, I just checked. I loaded the handbook in PDF format and searched under the word "spiral." Nothing. I then checked under each instance of the word "dive." Though the word arises repeatedly, none of the instances appeared relevant to spiral dives. Evidently, it's an overlooked topic.
  • Paul Hamilton
    by Paul Hamilton 5 years ago
    Down boy/girl. Experts are supposed to keep quiet to get the virgins, beginners and intermediate response first for this important question. However, experts raise important questions about the question…….Very insightful and relivent….
  • Paul Hamilton
    by Paul Hamilton 5 years ago
    Yea Glade, the FAA canned my spiral dive scenario in the FAA Weight-Shift Control Handbook. We do have a pitiful attempt at this on page 13-10 “Emergency descents” but that is it. Not that I like it,but the specific wing characteristics make a big difference in the spiral so some generic procedure is not appropriate to survival. Such is life……..
  • reb wallace
    by reb wallace 5 years ago
    Douglas by the time you reach the third spiral you have created about ( and this measurement is from seat of pants) 1 and a half to 2 G's of outward force making it very difficult to shift your weight laterally. so the outward push out on control bar should be gradual this relieves the outward forces from the spiral. then you can apply lateral force to control bar to level the wing, and this is done almost simultaniously power is added if your still sinking or loosing altitude ( ONE NOTE IS YOU SHOULD NEVER ATTEMPT THIS ON PURPOSE). I teach all students if caught in a spiral decent immediately correct with this procedure. Also as a note as a CFI I will never fly with student from the rear seat without dual controls as I don't have the capability to do this procedure with flying wires if student freezes on controls.
  • david coy
    by david coy 5 years ago
    hey all from montana first let me say awesome larry mednick this is great for tps and everyone is behaving so great iam going to take a shot at it and let me say i have never attempted or gottin in to this situation in my hang glider or trike nor would i and would hope not to be.there is alot of factors left out because air rises , sinks . shears , rotors ext and can influence the sinerio.but scince robs crash ive been goin over and over what i would of done and i hope it s correct save lookin foolish.ok iam found suddenly in high bank 60 deg sinking fast into spiral dive.and attentive quick response would be to back off power so iam not increasing foward vertical speed and cordinated in on the bar so iam not tightining the spiral and speed, and increasing the roll rate on the loaded wing.cordinated leveling or flattening out by pushing bar to the right. gracefully bleeding off the speed after roll out .as speed and clime is disapated add some power to return to level flight. paul are you going to grade us . i think if i couldnt manage the spiral dave quickly i would kill mags and go for the brs and hope for the best . ps paul why in the wourld would the faa can that info from youre book wouldnt they want us to know what to do if we got into that sinerio .so larry its f b c than a gradual
  • Larry  Mednick
    by Larry Mednick 5 years ago
    David Coy, thank you for your answer. Is your answer FC? you are describing?

    And BTW I am not linking this to any accident in particular. This is an unrelated question.
  • Larry  Mednick
    by Larry Mednick 5 years ago
    "however in about the 3rd spiral at 60 degrees bank it becomes very difficult to move the control bar side to side"

    This is very interesting. I too have experienced this in a multitude of wings. Some wings will do this in the first 1/2 rotation some wings will not allow you to move the bar sideways (to the right in this scenario)... a complete "lock out"!

    who else has experienced similar?
  • Rob Caya
    by Rob Caya 5 years ago
    F, C, then when wings are level A as needed to arrest decent by trading speed for lift. Then gradual application of throttle to arrive at level cruise. I was trained that the key points are F so that you don't feed the spiral, and then C (level the wing) to get out of it. I was told that recovery instinct in a rapid decent is to increase power, which in a spiral just tightens it. Pushing out tightens it by "climbing into it". We practiced them a few times and very briefly did the "wrong things" to see the effect. Doing the "right thing", chopping power and leveling the wings, was very effective. I have a video on my page of one practice flight where we did that, but it looked a lot cooler years ago when i shot it. ;<)
  • Uwe Goehl
    by Uwe Goehl 5 years ago
    Continue to push the control bar full left and push forward to continue maintain at least 1G during the roll for 300 degrees just like in the movies . . . No wait . . . may I change my answer?

    What I would do is bring throttle to idle, pull back on the bar slightly to unload the wing and push the bar to the right til wings are level with the horizon. The push forward to recover from the dive (decrease speed) and add throttle as necessary to maintain altitude to maintain level or climb.

    So, I guess all the above-- F B C D A E (all in a certain sequence and timing).
  • Abid Farooqui
    by Abid Farooqui 5 years ago
    I am sitting in Atlanta right now. Of course some wings will behave slightly differently. But there is an answer that will work with any well behaved wing regardless of its speed range, size or any of that stuff.

    Cut the throttle to idle if set at cruise. There are many trikes out there that are not compensated properly for torque and can have make situation worse and even induce further roll and overcome roll torque at high banks completely. You want to neutralize any chance of this.
    Slightly pull in and simultaneously level the wing and then adjust throttle and bar as necessary smoothly and you are done in a few seconds.
    Been there done that, got the t-shirt. Happened in a 17 meter double surface wing on a podded trike of high HP flying at 75+ mph with no wheel-pants ... what a dumb idea that was. The spiral developed after getting into something close to dutch rolls and wasn't started deliberately. Lost 1500 feet before figured it out. Didn't know what the heck was what at that time. Ouch! Happened in a Wizard wing, happened in Hazard wings as well (Larry saw it lockout on a badly balanced trike carriage). Its not just the wing that is to be considered, the trike carriage also makes a difference if its not properly aerodynamically balanced.

    Whether it was in an incipient spin or trying to go there, whether it was stalled and rolled into a turn that dropped the nose and got into a spiral, whether you applied full throttle making it worse ... doesn't matter. This gets you out. After being out smoothly let the bar out and smoothly apply power. You don't want to do things abruptly.

    End of story.

    Kael, no need for BRS for this. This is a non-event if you know what you are getting into. You'd loose 500 feet in less than 20 seconds but you'd also get out of it in less than 10.
  • Larry  Mednick
    by Larry Mednick 5 years ago
    ..."increase power, which in a spiral just tightens it."

    ..." Pushing out tightens it by "climbing into it"


    ..."it becomes very difficult to move the control bar side to side"

    These are 3 quotes from above from fellow trike pilots that have experienced this first hand.

    These 3 Points listed above are the critical points that need to be understood and make up the possible dangers of a spiral. A spiral in my opinion is no more dangerous and no less recoverable than a basic stall. And in my opinion spirals and stalls are the two most common causes of accidents in trikes. Fortunately I would bet 99% understand how to recover from a stall, unfortunately a lesser percentage actually execute stall recovery properly in a panic situation... BUT!!! I think it is a very "scary" percentage of trike pilots that don't really know what to do and were not trained and didn't read anything on the subject and yet (in my opinion) spiral/spin recovery is just as important as stall recovery. Worse yet mild Spirals can be stopped using certain actions where as aggressive spirals will not respond to the corrective actions that worked for the mild spiral causing some pilots to have a false sense of security to arrest an aggressive spiral they have never experienced yet.

    So here you have the scenario of some guys doing spirals on purpose and they "think" they know how to get out (and they do technically) and then one day they get into a very aggressive spiral or possibly a spin and all of the sudden only one combination of answers above works...

    So to re-phrase, which answer combination above works in ALL scenarios?
  • Bill  Pilgrim
    by Bill Pilgrim 5 years ago
    F,B,C then normal control inputs to return to level flight
  • scott smith
    by scott smith 5 years ago
    I have done this exercise before. (Ok maybe not losing 2000fpm but still decending) I have found that moving the bar so as to level the trike (I guess that would be C) will bring the trike back to straight and level. This is just my wing though. (NW Maverick and Gibbo's Manta) Both of these wings are pretty idiot proof, and forgiving wings. I have never tried such a thing with any of those racy models. I maybe did it wrong or maybe could have done it better, but it was a non issue maneuver that didn't even get my heart rate up.
    I am reminded of a story that I heard in the service where a pilot lost control of his fighter jet and ejected. After the pilot was gone and no longer trying to regain control, the plane righted itself and went on to land itself (fairly hard.) The airplane was repaired and flew again.
    Perhaps your quiz is a trick question. I am convinced that my trike would right itself from this situation if the idiot pilot (me) would just let go of the bar and throttle and let it do what it was engineered to do
  • Jan Ferreira
    by Jan Ferreira 5 years ago
    Scott, I think you are correct, as long as the ground doesn't comes in the way before the Trike rights itself.
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Hello Larry,

    Your scenario says:

    "SCENARIO: You are banked 60 degrees to the right and descending at 2000FPM at roughly cruise throttle setting at roughly cruise speed."

    This snap shoot seems within all flight limitations... I guess the 2000FPM descent rate is somewhat high... I mean 1/2 that descent rate and this sounds like a 60 degree descending turn. Specially because indicates the pilot seems to have complete control of speed at cruising, and therefore within maneuver speed.

    I see this a bit far from a spiral dive (I mean to me the word "dive"... indicates you will rapidly gain tremendous and extremely dangerous acceleration and likely, besides the high bank angle, the nose down attitude beyond limitation). A modern trike will gain speed very rapidly in such conditions. But I do not see a hint of that in your snap shot.

    To me one of the most dangerous attributes of a spiral dive is SPEED and how quickly it builds beyond aircraft limitations, But your scenario almost sounds that the pilot is in full control of such (speed) by actually maintaining power, descending at 2000FPM and yet not gaining speed.... in a 60 degree bank. Now - how can that be? ... there must be a trade somewhere ... altitude for speed....!? Perhaps some real draggy wings can do that... I can see that possible. I would caution on a fast low drag wing as likely it will trade rapid descend rate by rapid speed increase.

    Without an idea of the nose angle (how aggressive a dive or if beyond limitations) and if the aircraft is actually rapidly gaining speed as it turns/dives... is hard for me to consider other than a 60 degree dive turn at controlled speed ... at somewhat high descent rate ... and because the speed is well within limits (at cruise), just reversing the turn and a well balanced weight-shift aircraft will even tend to level itself ... in fact instead of pushing that bar much, may even need to hold some, as to not put too many G's into leveling - a gradual maneuver to arrest the rapid descend is best.

    Well - I guess my point is that more than an angle of bank within limitations ... it is the nose down attitude, and the rate of increase in speed that worries me in a spiral dive scenario and this one threw me off when I see the pilot is in full control, descending at cruise speed (within maneuver speed) ... I think a Wizard III 17 sqm SS cn achieve ... but a small fast single surface ... I think will be gaining speed quite rapidly in this scenario.

    TC
  • Tony  Castillo
    by Tony Castillo 5 years ago
    I will of course give it more thought ... but why a 60 degree bank angle at maneuver speed and within limitations is creating so many different recovery options ... is beyond me at this time.

    Why would reversing a 60 degree dive turn, would be so much different than reversing our fairly normal 45 degree dive turn?.... is it the 2000 FPM descent? ... and how can altitude lost (significant 2000FPM descent) is not traded by speed ... perhaps a extremely draggy & large wing!?

    I my opinion If we really want to discuss Spiral Dives in Weight-Shift, I believe we need to turn our focus to SPEED, specially the rapid acceleration, the demon that follows up during a dive and makes such so dangerous at many levels...

    And what contributes to such! ... many factors contribute to acceleration and high bank angle can certainly contribute, so is power, so is nose attitude. A 60 degree turn at maneuver speed is not outside the limitations, perhaps outside the comfort of some pilots... so I do NOT encourage those that are not comfortable with such but at the same time do not condemm a pilot for doing a controlled 60 degree turn.

    Is a great discussion here and Larry has made a great point. I'm glad pilots of ALL levels take these subject seriously and take time to think about and discuss.

    My observation is NOT to create a controversy of any sort or deviate from the great contributions here ... just want to point out the when we speak about spiral dives ... Nose attitude, Acceleration & Speed need serious consideration.

    Safe flying
    TC
  • Larry  Mednick
    by Larry Mednick 5 years ago
    Tony, you better believe a P+M or Revo is going to be at VNE in less than 5 seconds from this scenario.

    If you are coming down that fast you are aiming at the ground. Regardless, spirals in general are an increasing speed and G force maneuver that will exceed the aircrafts limitations if allowed to continue for long enough.
  • Doug Boyle
    by Doug Boyle 5 years ago
    In this scenario there may be some strange (little understood) vortices occurring contributing to a loss of lift. There is a phenomenon called vortice-burst inherent in delta wing planforms, which causes a reversal in vortice circulation preceded by an area of stagnation. As the burst develops it moves towards the apex but is lessened by an increase in incidence. Not sure how this translates into recovery methods but thinking about it....

    Fixed-wing recovery is well noted with a reduction of power and a leveling of the wings, but what if the delta wing won't respond to the desired roll-input? You might have to lessen the vortice-burst first through pitch-input. I've never explored (nor had the desire) to experience a high bank and descent rate three times around to find out....
  • Tony  Castillo
    by Tony Castillo 5 years ago
    That is precisely my point Larry .... the snap shot really does not indicate such! ... hint ... 2000 FPM descent rate - perhaps you intended that to be the hint ...

    Here is my point .. see if it makes sense. You stop the action at: 2000 fpm descent rate AND "....at roughly cruise throttle setting at roughly cruise speed"... my point is ... how can that be?

    By the time I reach a 2000 fpm descent rate, with cruise throttle ... how can I be at cruise speed :-( ... is that really possible? .... I will be going way beyond maneuver speed at such descent rare in a 60 degree dive.

    So I must separate one from the other .... if the snap shot is indeed correct and I'm truly within limitations (60 degree bank, high descent rate BUT at controlled maneuver speed ... ) .. that to me is one thing... and I reply based on that. I believe ... will verify ... such scenario may be possible and I believe a controlled 60 degree bank, descent with controlled speed can achieve such high descent rate ... but I would have to try to make sure.

    I mean, when you do a high degree turn to final, high descent rate, controlled speed ... what kind of descent rate you get? for sure over 1000 fpm easily ... could it be a bit more? and that is all within specs right?

    So when I mentioned ... sounds like a normal high degree bank turn to final, level and land! ... if I do a snap shot ... right there ... is possible we are almost identical?

    I'm wrong?
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Therefore I guess I really would have to see the nose attitude angle and acceleration to judge this as a spiral dive. Or just quit being argumentative ... and shut up ... ja ja
    TC
  • Tony  Castillo
    by Tony Castillo 5 years ago
    What is the difference between a controlled dive turn and a spiral dive? ... could it be nose angle, acceleration and speed? could it be there is not such as a controlled dive turn? ...

    I think I have dive in a high bank turn, and controlled my speed ... be good to know my descent rate ... but it is quite high. The banking within limitation, the nose at less that 45 degree but diving, speed controlled ... descent rate .. can't tell for sure but likely over 1000 fpm descent.

    Bank angle, nose angle, and speed well within the limitations... and we can do a safe turn and dive. I believe we do such quite often or we will never land! ... break ANY ONE of these rules and you are now a test pilot.

    TC
  • Larry  Mednick
    by Larry Mednick 5 years ago
    Tony, a controlled descending turn is a spiral if steep enough. At what point is a descent a dive?

    A spiral is not a bad word. A dive is not a bad thing. Neither indicates a loss of control.
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Larry, I think is important to point out that nose angle and acceleration to a speed (beyond limitations) makes an otherwise not bad thing, into a very bad thing. I see so much diversity of answers that I wonder if a distinction has been really understood. Because is the later that will get you. Anyways ... I see a lot of diversity on postings here and really should not be that way. I think.

    I believe the focus should be the nose attitude, and what is the acceleration ... that makes all the difference on how to arrest such situation. If we consider that indeed we are in a spiral dive and likely at or over Vne... G load is an important factor to consider during recovery. Well ... I leave it at that.

    You mentioned something earlier that really really got me thinking... you say:

    "This is very interesting. I too have experienced this in a multitude of wings. Some wings will do this in the first 1/2 rotation some wings will not allow you to move the bar sideways (to the right in this scenario)... a complete "lock out"!
    who else has experienced similar?"

    1) if you have experienced a "complete" lock out? how can you be here to tell me how you recovered from that! .... I'm not giving you a hard time (the word complete sounds quite "terminal" ) ... I am trying to understand the term. I have not experienced a situation that I have not been able to recover from (obviously...) ... so the lockout you experienced must have not been complete or perhaps reversible by something ... I wonder how you determine you are in a complete lockout and steps you took to recover.

    2) I assume such experience must be at a point that the aircraft has pass one or more of its limitations (speed, bank angle, nose angle) ... and could it also include positive G near or beyond limitation? (of course I assume negative G here is not the issue)

    I would like to explore this further. I may call you one day.
    TC
  • jeff trike
    by jeff trike 5 years ago
    Rethinking my answer, I would still do C first.

    If I couldn't move the the bar to the side because the forces were to great, I would have to try something else (or spiral into the ground). I need to take the load off the wing. You said throttle was set to cruise, so I am assuming the hand throttle was set.

    I would probably pull in a little first, and if that didn't work, move the hand throttle to idle so I could control it with my foot and reduce power. One or both would do the trick.
  • Michael Brandt
    by Michael Brandt 5 years ago
    I perform spiral decents all the time, because they are fun to do, and it's the only way to loose altitude quickly if needed. Am I not being a safe trike pilot by flying this maneuver?
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Michael,
    Precisely ... a bank turn dive within flight / aircraft limitations is not necessarily a bad thing (as Larry also pointed out). Giving you watch your dive angle, speed and banking rate. So - what is the difference between safe and unsafe. In my opinion when you take it to a degree that exceeds any one (or more than one) of the limitations.
    TC
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    I am wondering if all of us should not have asked Larry for an added piece of info, before attempting to answer. That is, does he describe a stable condition (i.e., bank not increasing, speed not increasing, nose not further dropping), or is the described state just one point in a rapidly worsening scenario.

    Regardless, I believe Larry tips his hand on this (two of his answers back) when revealing that, to be even momentarily in the described state (and at least as applicable to more slippery trikes) means the scenario is necessarily evolving, rapidly and for the worse. To state it otherwise, while the speed may indeed be only at cruise in this particular moment, it's only because it's the particular moment in a progression where we are passing through that speed while in a state of rapid acceleration.

    Larry, am I on the right track?

    Since our intrepid instructor has we students playing raise-your-hands-with-your-best-guess here, I want to continue, as novitiate, by articulating what I think I've deduced from this discussion regarding the distinction between a good and safe "turning descent" versus a potentially-dangerous-if-not-correctly-handled "spiral dive" (accepting there is no intrinsic difference in the meanings of the words themselves), I am wondering if the distinction is not as follows:

    A benign turning descent is easily maintained as stable. In other words, it does not require extraordinary control inputs to maintain a constant pitch, bank and speed. In the incipient stage of a dangerous spiral dive, by contrast, certain undesired dynamics come into play. If not quickly counteracted and in exactly the right way, these produce a rapid (and non-control-requested) change in attitude and speed. I am further led to guess these changes must mature into a new stable state that, like the classic three-axis-airplane spin, can be rather difficult to extricate from, if not done in just the right way.

    Larry, when does our teacher pull back the curtain and reveal the talking man?
  • Doug Boyle
    by Doug Boyle 5 years ago
    A spiral to me is an uncoordinated descent (your slipping out of the turn). As it develops, so does your descent rate. The turn tightens and you nose into the ground. This is in contrast to a coordinated descent with whatever bank angle, whenever it remains within the wing/pilot's ability to stay coordinated. Is this the distinction you're making Tony?
  • Doug Boyle
    by Doug Boyle 5 years ago
    Taildragger pilots use a slipping scenario most of the time when landing in a crosswind. Without top rudder to hold the nose up they too would auger in. The rudder is used in this case to maintain the runway centerline, and the slip's effect is to increase the descent rate. It's not dangerous until its allowed to develop without control input.

    Visualize the change of relative wind to the airfoil as a wing is spiralling out of the sky -- from straight ahead to sideways. The vortices begin at the nose and washout at the tips normally, but what happens in a spiral when the relative wind changes?

    I've been "locked-out" towing behind a boat before (where you can't roll back into the desired direction) but have always been able to release in time. The "last" tow where this happened (due to a winch operator being asleep at the wheel) resulted in a low-level wingover after release. The immediate push-out after release transformed the ground rush into a coordinated turn that resulted in a controlled landing in exactly the same place I popped-off from.

    The reason I fly trikes and don't hang-glide anymore is because I'll only accept my own mistakes in the pursuit of pleasure.
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Doug,

    Not sure about what you refer by slipping turn or uncoordinated ... I mean, you can be not slipping and fully coordinated and still intentionally quickly go beyond all aircraft limitations in an aggressive spiral dive.

    But indeed, my point is that staying and maintaining well within the limitations (speed, bank, attitude) and it is safe... that applies even if you are in a descending turn. And as pilots we command our aircraft, and the aircraft performs as directed.

    Intentionally piloting outside the limitations, or not arresting the problem before it becomes a problem, is not an aircraft problem, it is a piloting issue. If we do that in purpose then we are test pilots by choice (do not take passengers and record your findings), but if that happens unwillingly (and not due to an aircraft defect but our own) then is time for a refreshing class with one of our fine instructors. You bet I will be the first in line if my aircraft out-flies me!

    I hope this does not sound too harsh ... but we are PILOTS which means we pilot our aircraft ... not the other way around I hope.

    TC
  • Doug Boyle
    by Doug Boyle 5 years ago
    What I'm saying Tony is that, by definition, a spiral dive is one where the nose is allowed to fall through the horizon. We push-out to keep this from happening, thus coordinating the turn. By contrast, a descending turn contains the correct amount of push-out for the given bank angle. Therein lies the difference between a spiral turn and a descending turn.
  • Mike-in- Thailand
    by Mike-in- Thailand 5 years ago
    FBC - in that order.
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Doug, that is not what I read from Larry's scenario posted here ...!?
  • Tony  Castillo
    by Tony Castillo 5 years ago
    and why would a trike pilot do something like that ? :-(
  • Doug Boyle
    by Doug Boyle 5 years ago
    Tony, I'm addressing your scenario comparing a spiral dive to a high-banked descending turn.
  • Tony  Castillo
    by Tony Castillo 5 years ago
    A high bank descending turn i believe is at times referred as spiral dive. Like the subject here. I believe the description larry made is a high bank high rate descending turn and the subject says spiral dive
  • Tony  Castillo
    by Tony Castillo 5 years ago
    The manufacturer also refers to this kind of maneuver a spiral dive.
  • Doug Boyle
    by Doug Boyle 5 years ago
    I'm trying to make a distinction between the two: the spiral I'm referring to is 1) uncontrolled and 2) dangerous, whereas the high-bank descending turn is not -- for the seasoned pilot. And the distinction I'm relying upon is uncoordinated vs. coordinated, which is accomplished by the correct amount of push-out and the recognition of a turn that can become dangerous (death spiral).
  • Doug Boyle
    by Doug Boyle 5 years ago
    The 2000fpm descent rate in Larry's scenario should be a clue as to which one we're talking about.
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    Forgive my ignorance, but I've been entertaining the understanding that in WSC aircraft, uncoordinated flight is not generally an issue. As I understand its application with 3-axis aircraft (and to contrast), it is important there to "coordinate" aileron and rudder to keep the fuselage longitudinally-aligned with its vector of travel through the air (i.e., not side-slipping). In WSC aircraft, we do not have any separation of controls to keep coordinated, and instead rely on wing dynamics alone to control yaw.

    Perhaps what I am missing is that side-slipping is a dynamic that set's up in the particular variety of uncontrolled spiral dive that's at issue here (which I think, Doug, is exactly what you are saying). But I am finding it difficult to make conceptual sense of this explanation. It seems to me that slipping out of a turn would result in lessening of its incidence (and a decrease in speed), rather than intensifying both factors. Isn't such lessening precisely what results when, via side-slipping while in a turn, a 3-axis plane slips into a spin (this question is not rhetorical; I truly am not sure)?

    The desire to understand this is really bugging me. I think perhaps Larry truly has exposed a gaping "black hole" of ignorance on a crucial topic. As further evidence of this, I've Googled the matter, seeking a definitive description of precisely what are the in-flight dynamics as involved in an uncontrolled WSC spiral dive. I found nothing that was satisfying.

    I have found myself uncontrollably seeking to visualize the dynamic just now. I'm going to think "out-loud" (actually, via typing) and see if I can speculate a potentially accurate (or at least superficially credible) picture.

    Say I voluntarily go into a descending turn. It feels good, so I increase bank and pull on the bar a bit more. In consequence, both bank and my nose-toward-earth angle become more extreme, so speed builds still more. As speed builds, the wing encounters its natural tendency to wing-axis-pitch-up in the face of higher speed. Here is where I think there might be a critical distinction that makes this situation dangerous.

    In straight-ahead flying, this pitch-up-with-increased-speed tendency (as present in our WSC wings) naturally trends toward maintenance of reasonable speed. It's because, as wing-axis-pitch-up occurs in this particular roll attitude, the aircraft's vector of travel changes from downhill (collecting energy from gravity so as to build speed) to uphill (surrendering energy to gravity so as to lose speed). In consequence, the pilot has to actually "fight against" the wing's natural tendency, to maintain a deviation from trim speed. Indeed, he has to fight especially hard (that very muscular and constant pull on the bar) to maintain a speed significantly above trim.

    As I'm imagining it, at least, the highly-banked downward turn creates a completely different scenario. Here, as speed increases and the wing encounters its natural pitch-up tendency in consequence (on its pitch axis, not on earth's), there is almost no consequential effect to control speed. This is because, with the aircraft banked at 60 or more degrees, the wing-axis-pitch-up is not longitudinally opposed to gravity (or at least is very little). Stated otherwise, at such bank it does not significantly change the aircraft's vector of travel toward uphill. There is, indeed, almost zero such salutary effect. Instead, that natural wing-asxis-pitch-up tendency (if allowed fruition by the pilot, and in this specific situation) tends only to tighten the turn, and steepen the bank. The steepened bank, in turn, means decreased ability from the wing to help the nose resist gravity's tugging force, so the nose drops even more toward earth. In consequence there is even more speed, and whole dynamic becomes a self-reinforcing feedback loop. Hence, our topic.

    At least the above is what I just put together, thinking it through. I wonder if it's accurate? If it is (maybe) accurate, I further wonder what would be the best way to escape from such a flight dynamic?

    At least in the scenario as described (assuming it might exist), the main thing that initially allowed severe deterioration of flight conditions was the pilot permitting the wing to pitch up, when at steep bank and when such was its inclination. Given that this was the main triggering mistake (again, assuming accuracy in the scenario), I believe it makes sense that the first corrective action should be to pull the bar back. Not harshly, but enough to broaden the turn and (in direct consequence) decrease bank. As bank decreases (and the wing becomes more perpendicular to gravity's pull), it should be possible for its lift to begin again raising the nose back toward horizontal vis-a-vis earth (indeed, if the speed became high this will be the natural tendency). Of course, a bit of sideways pull on the bar (opposing the angle of bank) will help the bank decrease more readily. And, if it's a situation had indeed progressed far enough to endanger overspeed, the throttle should be reduced momentarily to idle (so as to not add its own contribution to overspeed).

    For the particular scenario Larry describes, overspeed had not yet occurred, and I believe the real danger was only incipient. So (and on the basis of assuming, perhaps wrongly, that my above analysis is sensible), I provide a new (for me) answer to Larry's query:

    B (pull the control bar in); and
    C (move the control bar to the right).

    I believe, likely, these two actions would ideally be all but simultaneous, but I list B first because, of the two, I suspect it is more important (though perhaps I have it backward; I don't know). I am not listing F (go to idle) because, as described by Larry, there was not yet any overspeed, and with immediate application of B then C I suspect any such tendency would be nipped in the bud. I am also not listing A (push the bar forward), in spite of the fact one would want to let the bar move forward (and perhaps push a little) after other conditions were stabilized -- if desiring to resume straight-and-level flight. This is because, based on the fact we were already in a descending turn, I am assuming perhaps that is a condition we desired, but nevertheless also need to control.

    Hope I haven't made a fool of myself.
  • Doug Boyle
    by Doug Boyle 5 years ago
    Glade, I think the description of the nose "naturally going up" in a high-banked turn is incorrect. This is why we have to push-out in a high-banked turn. This push-out serves to "coordinate" the turn. Too much push-out creates (in theory) an accelerated stall. Too little pushout (or none at all) allows the wing to side slip. My Tanarg self-coordinates up to about 40 degrees of bank (this may be your impression of the nose "naturally going up"). Your Clipper probably has similar characteristics.

    Your visualization of this topic is right "on-time" for the arrival of your Revo.
  • Abid Farooqui
    by Abid Farooqui 5 years ago
    Guys: This is a turn where the turn was not co-ordinated (in the trike sense not the airplane sense). The nose is allowed to drop rather badly while banking steep. It doesn't just happen. Someone makes it happen

    The thing you do not want to do at all, I guarantee you in this are
    1) Push the bar out
    2) Hit full throttle

    These will take you to higher rate of descent and possibly closer to terrain if you are already in this spiral dive descent. Do NOT DO THAT. You will regret it if you live through it. It will make things worse. I am surprised to see so much misunderstanding on this very basic recovery.

    If you don't like pulling the bar in (unloading the wing), ok, try leveling the wing by itself but that is still more dangerous then first unloading it. I can guarantee that pulling the bar in slightly while simultaneously giving input to level the wing will be the easiest foolproof way of getting out.

    Take the above advice. LEVEL THE WING first. To make it easier and smoother and less G intensive, unload it a bit and level it simultaneously, get rid of the power. Only once you are out of the spiral, smoothly, slowly and deliberately push the bar forward (at high speed 3 inches of push forward will make a much larger difference than normal) and smoothly, deliberately apply power. Don't make it worse by pushing the bar out and hitting the power. You WILL GO DOWN EVEN FASTER. This is not your controlled descending turn we are talking about. Spiral dives are referred to specific situation with increasing accelerating speed and rates of descent. There is no danger in doing descending controlled turns. Its when they are badly executed with other mistakes like power applied etc. that they transform into spiral dives.

    Someone mentioned Manta etc. Oh your wing goes there trust me. You just have not done it and been there. Most wings can get to go there. Trike wings at steep banks are not positive roll stable. And almost any trike wing can go right past its Vne in this scenario. Pushing the bar out, you can go over the load limits for maneuvering and go towards ultimate load factors. Not a good idea.

    Its that simple.
  • Paul Hamilton
    by Paul Hamilton 5 years ago
    For me, this is one of the most important/interesting topics/conversations on this site for the year.
  • Abid Farooqui
    by Abid Farooqui 5 years ago
    I do have to (should) put in the following exception to the normal recovery I have written above and emphasized.

    This non-normal reverse recovery is for badly executed, badly tuned wings or wings that stretch sail with age pretty badly like old Ravens.

    Its best to just put out the notes I had when I was discussing it with Paul Dewhurst. Certain wings with little or lower tension and too few outboard bottom surface battens will balloon downwards, giving negative pitch stability and locking into a spiral dive. Make sure the tension in your wing is enough that this does not happen. The wing in question in the accident GT-5, has adjustable tension. In Australia I am told, a wing sail that has decent enough tension down in FL has extremely loose tension in Australia due to weather differences and has to be tensioned a couple of notches to make it like it performed in FL. etc. etc.

    Notes:
    > Abid, you are right that if tension is too low the undersurface balloons
    downwards, giving a negative effect to pitch stability - and may also effect
    lateral stability and roll response - again a reason why Rick may have found
    roll response better with more tension applied.
    >
    > They did have a big problem in that regard that in a spiral dive with low to
    medium tip strut tension the inner wing undersurface would balloon downwards
    and lock the machine into the spiral and it would not recover with roll input.
    at least one fatal was put down to that as a highly probable cause I was told.
    Trick was to push forwards to deflate the tip and then roll out of the spiral.
    For number of years we had to teach this 'reverse recovery' specifically for
    Ravens.
    >
    > Problem was it couldn't be cured just by adjustment. The wing suffers from
    ongoing sail stretch and very 100 hours or so needed a lengthening of the tip
    struts to maintain tension. Old wings eventually ran out of adjustment - or non
    expert check pilots didn't know what to do and when to do it, and owners didn't
    notice the creeping change often.
    >
    > however it was later cured by an extra undersurface batten near the tip, which makes it far more tolerant of low tension.


    This is why I prefer conceptual understanding of the problem rather than rote actions but honestly, this falls in the quadrant of "test pilot" and should never occur in normal end user and even instructor flight envelope. But just thought I'd throw it out there, just in case someone has something that behaves this way after being tuned with very low tension in sail or with sail stretch etc.
  • Doug Boyle
    by Doug Boyle 5 years ago
    Two areas of study here are 1) relative wind and 2) lift vectors, to aid in our understanding of what's at play in this scenario.

    One anedote that helped me in the early days concerning the relationship of AOA (angle-of-attack) and Relative Wind: dive bombers would scream towards the ground and then aggressively pull-up at the last minute, only to stall and pancake into the ground. An abundance of airspeed, so why the stall? A stalled configuration only seems to be a function of airspeed, right? Wrong!

    The diving bomber changed the relationship of the Relative Wind during the manuever. A stall is a relationship between AOA and RW. During the pull-up the critical AOA was exceeded and the aircraft stalled into the ground.

    In a high-banked descending coordinated turn we aren't convuluting the RW; in a spiral dive I think we are! Visualize the wind hitting you in the face when coordinated; then think about the wind hitting you on the side of the head as you slice sideways falling out of a turn. A change in Relative Wind?

    Pictures are better than words when digesting "lift vectors." Consult your favorite Aviation textbook to see the changes in a high-banked turn between coordinated vs. uncoordinated, carving vs. slipping, with special attention towards centrifigal force in both examples.

    Another example which may be worthless places you on snow skis, learning how to carve your turns while going down the mountain. You unweight and then weight your skis as you carve your turn. If you do it correctly, you remain on your feet; if not, centrifigal force wins and you get snow down your collar. One way may be referred to as "coordinated", while the other might have you labelled as "uncoordinated."

    If you've never been in a true spiral dive, then GREAT -- please don't explore in a delta wing.
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Doug, although the spiral dive you describe is indeed common in fix wing airplanes, in a Weight-Shift I do not really see that scenario very likely. The natural tendency of the flex wing is for the nose to follow the direction of rotation and also find pitch stability. The only way I visualize such would be the pilot pushing the bar out quite forcefully, and keeping it out while in a dive turn and that is quite unnatural. Help me here!
    TC
  • Doug Boyle
    by Doug Boyle 5 years ago
    Tony, What happens in WSC when you maintain a high-bank turn without any push-out?
  • Tony  Castillo
    by Tony Castillo 5 years ago
    nose drops... ?
  • Tony  Castillo
    by Tony Castillo 5 years ago
    it does not come down sliding in a wing ... the nose drops and gain speed ... dangerously rapid may add.
  • Doug Boyle
    by Doug Boyle 5 years ago
    And why is that?
  • Doug Boyle
    by Doug Boyle 5 years ago
    Why does the speed increase?
  • Paul Hamilton
    by Paul Hamilton 5 years ago
    OK here is my answer. http://www.trikepilot.com/videos/view/paul-hamilton-performs-a-spiral-dive-with-recovery-left-and-right_17090.html
  • Ted  Bailey
    by Ted Bailey 5 years ago
    Are Spiral dives really considered unsafe in the new generation
    of trikes/wings? I have been doing them since the early 80’s and
    always considered them as safe as any other maneuver.

    If you are entering a spiral dive to lose major altitude or escape
    some massive lift you would be reduced from cruise throttle to
    high idle. I can set my bank and control my speed with normal
    pitch inputs and then add or reduce Gee load by twisting the bar like
    a motorcycle pushing the nose over into or out of the turn. More
    control pulling Gee’s this way than by pushing the bar out. The
    last thing you want is to slow down and be sucked back up.

    I have never had a lock out in a spiral dive, but have experienced
    lock out in a HG(not from a spiral dive) and aggressive pitch usually
    breaks it free. This has always been a roll in and a roll out maneuver
    for me. The only time to do this with high throttle settings is for entry
    speed to other maneuvers.

    I fly 13-15 meter DS wings on mostly under-powered simple stick
    trikes that stall ~30 with trim speed of 50-55 and VNE 85-90.
    2000-2500 fpm down is easy on a HG even more so for the trike.
    Advantage goes to the draggy 103 trikes?

    If you fly/soar light trikes and ever get stuck in the express elevator to
    the white room it may be the only maneuver that can save you.
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Doug, I assume the speed increase because you are in a dive!?
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Paul ... in a spiral dive you won't be flying into your own wake! Your video looks like a high banking maneuver indeed but I do not see the extreme nose dive, or descent rate that has been suggested here by Larry's example. You won't be flying your own wake if you are descending at 2000 fpm
  • Doug Boyle
    by Doug Boyle 5 years ago
    Tony, Technically, this defines a slip. The speed increases because you are slipping. If you tie a piece of yarn to your flying wires it will point towards you when S&L; but, enter a right slip, and it will point more left. It's an indicator of Relative Wind. Coordinate that turn and the yarn will once again point towards you. Sailplanes and sailboats call these "yaw strings."

    A "slip" is the entry into a spiral dive, if left uncorrected. It will only get tighter in radius and steeper in descent, as it develops.
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    There may be a need to clarify meanings. The term "nose-up" can potentially be used to reference the aircraft's pitch axis (which I'll here call "Sense1"), or might instead be used to reference changes relative to the ground (which I'll call "Sense2"). If it's not clear which sense is meant, understanding will suffer.

    To illustrate the difference, where an aircraft is flying straight and level the two "Senses" are aligned (i.e., nose-up in the aircraft's pitch axis also means the nose points relatively away from the ground). Where you're at a steep bank, they diverge. At a 90 degree bank, in fact, they are entirely uncoupled. At that particular bank, indeed, Sense1 pitch changes become the equivalent of yaw if judged from a Sense2 perspective (in other words, as viewed from the ground changes in the aircraft's Sense1 pitch are seen as rotation along a horizontal plane and about a vertical axis).

    What I have personally observed in turning is that, up to about a 45 degree bank, if the nose begins to drop Sense2 (i.e., toward earth), it's perfectly effective to adjust it back upward (Sense2) by pushing out on the bar. In other words, Sense1 nose-up (bar-out) remains effective in producing Sense2 nose-up. At bank levels increasingly greater than 45 degrees, however, I discover that pushing the bar out (Sense1 nose-up) becomes increasingly ineffective in producing Sense2 nose-up.

    It's only logical the above should be true. At bank angles less then 45 degrees, Sense1 and Sense2 are still significantly aligned. Stated otherwise, a nose-up change in reference to my aircraft is also (in significant degree) a nose-up change in reference to earth. At bank angles increasingly beyond 45 degrees, however, this becomes decreasingly true (and becomes not at all true at 90 degrees banked).

    Given the above, I suspect, for any WSC design, there is a maximum bank angle that can be sustained without the nose falling toward earth. In other words, while it may perfectly possible to go briefly into a 90 degree bank with the aircraft's Sense1 roll-axis remaining Sense2 level with earth, if I want to pick a bank angle that's sustainable for a longer period, it's likely the most I can manage will be something closer to 50 degrees. If attempting more (more than whatever it is that happens to be the max), the bar-out action (nose-up Sense1) is not sufficiently effective as a means to keep the nose from falling toward earth. At such angles, its main effect instead (and as mentioned in my last entry) is to increase AOA and tighten the turn (if persisting in this progression, moreover, my AOA will inevitably surpass the stall threshold).

    Though I've never been trained in a 3-axis plane, I suspect there may be an interesting contrast there. Suppose I am in one that's built with sufficient strength for the purpose, and I wish to maintain a long and sustained 80 degree bank. In contrast to a WSC aircraft, I there have a rudder. I suspect at such a bank my rudder can be used to keep the nose from falling toward earth (i.e., to avoid nose-down Sense2). I suspect I can also use my elevator to either shorten the radius of my turn (nose-up Sense1, equivalent to bar-out WSC), or to lengthen it via opposite action. By reason of this distinction, I suspect a 3-axis plane can likely sustain a much steeper bank than can a WSC.

    The difference in WSC is we do not have a rudder to keep the nose kicked up (away from the ground) while in a 90 degree (or otherwise very steep) bank. Bar-out (nose-up Sense1) becomes ineffective for the purpose, and we aint got nothin' else!

    I should re-emphasize, the above is the mental model I've presently painted for myself on this matter. It seems logical to me, and seems to fit my experience in actual flight. Regardless, I am not presently certain of its accuracy.
  • Larry  Mednick
    by Larry Mednick 5 years ago
    I have prepared a video demonstrating a spiral dropping at one point at the 2000 FPM descent rate described. Coming shortly...
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    Larry, I can't wait.

    Regarding clarity between nose-up Sense1 and nose-up Sense2, I just looked at my post from yesterday and noticed, while in my description I was always certain of which of the two I meant, my actual words were often unclear. I have just revised that entry a bit, in the effort to clarify.
  • Doug Boyle
    by Doug Boyle 5 years ago
    Glade, It's great that you're looking and thinking about it, but don't over-think it. No rudder is needed in a turn after it has been established -- unless you're performing an aerobatic manuever! You're simply adding enough pitch for a given bank angle -- this coordinates the turn. You're neither slipping or skidding in the turn. If you had a turn-and-bank instrument, your ball would be centered. A "yaw string" would be centered, as well.

    We're limited to 60 degrees of bank, from which there is enough push-out to coordinate the turn. Since your lift is reduced and your stall speed is increased, there will also be a need for more power. Your nose will appear to stay in the same place on the horizon as you complete your turn.

    If while in the turn the nose drops through the horizon, let that be your signal to begin recovery or remedial actions.
  • Tony  Castillo
    by Tony Castillo 5 years ago
    Wonderful Larry :-) ... I think if it wasn't because its cold and windy here ... I will be likely be doing the same. I'm so curious to see what kind of dive / turn gets you to 2000 fpm... I do believe that the ones that "bite" go beyond 2000 fpm :-( ... but until I see the 2000 fpm one ... can't tell for sure!
  • Tony  Castillo
    by Tony Castillo 5 years ago
    take a spring and stretched a bit ... put it vertically and fly the path the wire in the spring makes.... well .. you are in a spiral dive, stretch some more .... fly the path ... you are in a spiral dive ... stretch a lot ... fly the path .. you are in a spiral dive. are all those flights dangerous ... nop... to what degree you stretch the spring that you would consider following & flying the wire path to be dangerous?

    Ok ... don't fly it now ... just put a little car to ride the spring ... stretch ... there will be a direct relation to SPEED at witch the cars is racing and turning ... it likely at some rate of descent the angle is so steep and the speed so fast ... the little car will run off the track! .. exceed some limitations.
  • Herman Eldering
    by Herman Eldering 5 years ago
    Best topic, i've yet noted on TPS, educational, thought-provoking, even pilots of hundreds of hours experience are wisely re-evaluating their attitudes. Never too experienced to learn is a good motto. Above all learn these lessons before a nasty event strikes and a few seconds hesitation can become a tragedy. Larry you deserve the deep gratitude of us all for being so willing to share your knowledge so selflessly. Its also much appreciated by Australian Revo owners that Larry is willing to come over and spend days of his time making sure that his Revo owners here are completely familiar with all operating parameters.
  • Brian Reynolds
    by Brian Reynolds 5 years ago
    After reading the post I realized I did not understand the forces involved. I watched Paul's video which seemed to me a controlled steep turn which is what I have done thus I withdraw my answer.This spiral that is in question must be horrific in not knowing what to expect. Once I understand I will only practice it in the hanger.
  • Doug Boyle
    by Doug Boyle 5 years ago
    B, C, F
  • Wesley Frey
    by Wesley Frey 5 years ago
    I uploaded 2 versions of the SPIRAL DIVE video and they are processing. The second one is a smaller file and will probably finish processing first. Larry talks over a demonstration video to explain what doesn't work and what does.
  • Wesley Frey
    by Wesley Frey 5 years ago
    OK. I uploaded 4 of them. Please go to You Tube and search for wesfrey11. My channel has 44+ videos, but the latest 3 are the spiral dive videos. Pick one that plays. I can not figure why they are not playing for me on TP.
  • Wesley Frey
    by Wesley Frey 5 years ago
    http://youtu.be/vgRVpw7TvrY
  • Rizwan Bukhari
    by Rizwan Bukhari 5 years ago
    Wes,

    The last two that you uploaded are playing just fine
  • Paul Hamilton
    by Paul Hamilton 5 years ago
    Wes,
    Both videos here at TPS are playing fine for me also
  • Wesley Frey
    by Wesley Frey 5 years ago
    Thanks. I fixed it so just one is playing now:
    EXIT A SPIRAL DIVE IN A TRIKE
    http://www.youtube.com/watch?v=vgRVpw7TvrY&feature=share&list=UU9vJiufm8sqUh17PpA2NIgw
  • Glade Montgomery
    by Glade Montgomery 5 years ago
    Thank you Larry. It's great to see the answer. I suspect you may have saved some lives.
  • Rob Stapleton
    by Rob Stapleton 5 years ago
    Thanks for the question and the discussions. This site is getting more interesting as time goes on. I suspect the F, B, C, answer is correct in that unloading the wing will be needed by a reduction of power, neutralizing the bar, then pulling the bar in once the load is diminished and then once unloaded opposite wing input to level flight or at least a pull out.
    Good stuff and better demonstrated by an experienced pilot instructor. Not by a low time trike pilot at 500 feet.
  • wexford air
    by wexford air 2 years ago
    The answer is.............
  • Larry  Mednick
    by Larry Mednick 2 years ago
    F B C. Possibly F C

    http://www.trikepilot.com/videos/view/exit-a-spiral-dive_17102.html
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