Rod Schramm's Photos - Performance 103cs UL

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Album - Performance 103cs UL

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14 Comments

  • Larry  Mednick
    by Larry Mednick 2 years ago
    Awesome project, reminds me of my journey "prototyping"

    Just wanted to point out that the down tubes on the A frame will need to be straight when you complete your project. otherwise they would just buckle under load. They are under a large amount of compression during normal flight. Obviously yours are just mock ups at this point, but IF you are planning on trying to widen the upper section of the A frame, you will need to lengthen the control bar and then beef up the material of the control bar etc. but keep the down tubes straight.
  • joey martin
    by joey martin 2 years ago
    I really hope you look more at what larry is saying that looks as if it could be a major problem. i can see the control bar rising once the wing is loaded. some sort of jig needs to be made to hold the keel in place to some how load or lift on the wing tips to do some ground testing 1st. if this is just a mock up please over look my comment but if this is the intended design please test test test on the ground.
  • Rod Schramm
    by Rod Schramm 2 years ago
    Thanks for your input!! The down tubes are 1piec, in the pic shown here it was just a bit of a problem because i did not have the right tubing at the time. the down tubes will have a 45deg bend in them and i have done extensive load testing and FEA analysis on the stress of the bend areas, the load that our down tubes will take in flight will not be an issue. This was one of the unknowns and issues i had for a while. The problem with a straight tube is that it would not allow a 20deg left or right full turn at the top of the cabin, although typically this movement is rarely done in flight. Also I wanted to make the install for the new wing parts as simple as possible and therefore i only need to make a few parts for the control junction and supply new flying wires to locate the control bar.
  • Larry  Mednick
    by Larry Mednick 2 years ago
    What maternal are the new down tubes made of?

    How much load can they take? Better yet how much load do they need to take?
  • Gregg Ludwig
    by Gregg Ludwig 2 years ago
    I've seen some load tests pictured where sandbags are simply loaded on top of the wing but this does not really simulate an inflight load where the wing is providing lift and the downtubes are under considerable compression. A good wing design should also inspire confidence by appearance and I don't think bent downtubes would be well accepted by pilots or passengers. The project, however, looks most interesting.
  • Joe Hockman
    by Joe Hockman 2 years ago
    Rod, I really like your project with partially enclosed pod. This is a great innovation for 103 trike pilots. I have been an UL pilot for close to 4 decades so this is particularly appealing to me.

    However, if you don't mind, I will be very blunt on my comments. I know of no tubing material that would reasonably be considered for 103 down tubes that will with stand the compressive loads on a 45deg bend. Remember you should be thinking along the lines of 6g positive loads. For simplified calculations, let say you assume 500 lbs max total wt, 6g would be 3000 lbs, split that between 2 down tubes and you have each down tube under a compressive load of 1500 lbs (this is of course approximate as geometry of control frame would need to be considered for more accurate calculations). What AL alloy tube with what tubing dimensions and wall thickness would be needed to with stand a 3/4 ton compressive force on a down tube with a 45deg bend? I don't think you will find one. Frankly even thin wall steel tubing would not with stand that load.

    However, I'd like to suggest a "possible" solution to consider. Such loads might be acceptable if you were to build control frame from 2 straight down tube sections/side and specially fabricated elbow along with a cross bar above cabin between those elbows. The upper control frame (section above cabin) would take vast majority of loads and down tubes from elbows down to actual control bar in cabin would only take a portion of max loads. This would probably require both front and rear and side flying wires to those elbows as well as to the lower control bar. Not sure it would make sense to use side struts on a strutted wing if struts connect to actual control bar vs upper cross bar since the upper section would take majority of load. Now a side effect of this approach is that the smaller control frame above cabin would have to with stand higher compressive loads (upper down tubes) and higher tension strength (upper cross bar) so materials would have to be selected accordingly. In any case, I am quite confident such an approach would work IF design and materials were properly done. Just offering as a suggestion to consider.

    A separate question. Do you know about how much the composite pod or cabin will weigh with or without engine? Wish you the best on you project.
  • Rod Schramm
    by Rod Schramm 2 years ago
    Thanks Joe and everyone again for the comments. Let me first say that we have a 2 for 1 deal from the tooling, the first trike is the Performance 103 cs, it has a total of 650 gross. It is a far 103 trike, everything minus engine and wing weighs only 74lbs, the total will be right at 254. We also have the ability to upgrade the Engine, wing and gear for a single place Ex/am built aircraft. It will have approx 18-20gal of fuel. i am hoping to get a wing with 10.5-11m, place a 80hp engine on it and be able to have a cruise of 120-130vne. I might just build a full carbon ridged wing for it??? i would like to see a 1000-1500ft/min rate of climb and stall around 30ish.

    So to answer the question regarding the 45deg bend in the down tube and load: If you look at really how the loads are going into the strut, lifting and bending points of the wing and also factor in the flying wires the true load for a part 103 down tube with a safety factor of 4 is roughly 650lbs. If i place a 2024 1.125 od X .065w tube in that spot and have 4 points connecting to the tube, (one connecting point will be slightly above the bend and one 10.5" below), this will not only give the bend a helping hand in the load calculation by removing 200lbs of bending force, but also helps the pilot be able to get in and out so much easier. Also right in the bend will be a gusset with a few "lightning holes". this completely increases fatigue life of the part and in turn makes it act like it as a straight tube to begin with.

    Lastly just to answer Larry's comment "A good wing design should also inspire confidence by appearance and I don't think bent downtubes would be well accepted by pilots or passengers".

    All i have to say is didn't the Wright Bro's get stopped be many on lookers that told them that very same thing?? I believe they inspired the world and if my Dad had let people say that needs to be acceptable to other pilots do you think he would have ever sold 5000 helicopters, have 10 original designs and several engine pattens?? I think not. Bent down tubes or not she will have very little drag and that my friends is what I'm sticking to. lol
  • Larry  Mednick
    by Larry Mednick 2 years ago
    That was Greggs comment about it looking funny.

    I probably trust your gusset. It's the tubes coming off the junction that are probably more at risk of buckling.
  • Gregg Ludwig
    by Gregg Ludwig 2 years ago
    ya, that was my comment. But furthermore, as I heard somewhere, apply gussets or sleeves or whatever, but a noodle is always a noodle. An interesting project though for sure.
  • Rod Schramm
    by Rod Schramm 2 years ago
    LOL good stuff and cant wait to shake hands peeps!!
  • joey martin
    by joey martin 2 years ago
    rod we have a little more technology then the wright brothers some times we get blinded by our own visions we are just pointing out the obvious and for that reason i say fly safe but i won't be the test pilot....lol
  • Joe Hockman
    by Joe Hockman 2 years ago
    Rod, if every thing minus the engine and wing is only 74 lbs then that is lighter than I had expected. That is awesome. So is your composite just a carbon fiber (CF) cloth (a few layers?) set in a resin or is it fiber glass embedded in resin? You should be able to easily meet part 103 weight. If parasitic drag from pod is that much less then a stick trike then it really should not require much more than 30 to 35hp and still get great performance on a trike.

    Yes, if you have gussets reinforcing those bends then that should help a lot with reducing compression loads on the down tube bends. However, you still have bending/buckling loads and stress to contend with. This may call for one or more sleeves to distribute loads. I also would think that a cross tube or cable between gussets would really help to reinforce the upper A frame. Also it does not appear that it would interfere with cabin and range of possible roll control inputs. From pics it looks like you are modifying a NW Maverick III wing which is an excellent choice for this project. I wish you the best in this project and would definitely like to hear about experience/perspectives on initial test flights.
  • Rod Schramm
    by Rod Schramm 2 years ago
    Joe, the bid layers are very complex multiple layers of 5.5oz CF, 8.7CF and 3oz Kevlar along with 2 layers of 1/8" foam. Around the window/door track it is 1/2" to 5/8 thick, this is super strong and will be superb in a frontal impact or roll over. I have studied indy 500 cars with the same bid layers and the destructive testing they do is far better then any welded substructure could handle, this is what i am also looking for. I did a simple test in a video on youtube, (look up stressedout72 there), where i sat on the same area and it didn't even move. I also placed 300 lbs in the same area and was no problem. that particular point only needs to hold 300 lbs in a +/- 4g. This is all a hand layed process if we did a vac process the cost of the final product would skyrocket.
  • wexford air
    by wexford air 1 month ago
    This is a really interesting project and I can't wait to see the finished article. If you want to test the a-frame (downtubes) try putting weight in the cockpit and jacking the whole lot from the bottom corners of the a-frame. Provided the centre of balance suits of course!

    Not that I'm a crash Gordon or anything but the few mishaps I had I was glad the trike was made of nice bendy aluminum to take most of the impact, be interesting to know how carbon fibre works in this regard.
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