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  • jeff trike
    by jeff trike 11 days ago
    I bought a Rival-X wing for my Cobra-912 trike this spring and have had a chance to put a couple hours on it. Here are my thoughts on the wing.

    First off, I am extremely pleased with this wing. Workmanship is excellent everywhere. I won't bore you with all the details, but everything about the wing is well thought out to make the wing set up very easy from the bag. The only time I needed an extra hand was to open the wings up and set the wing on its nose during assembly.

    I like my wings nice and stable. I am not an aerobatic style pilot, but I want my wing to handle thermals and mechanical turbulence coming off terrain. My two previous wings were the Aeros Stream and Air Creation Nuvix both which were very stable and stiff in roll. I have flown the Aeros Profi and the Air Creation Bionix, also very stable in roll.

    I was looking for a wing that had lighter handing, and a wide speed range. I had to fight some hellacious head winds on my last couple long XC trips. I was worn out with my hands crippled with carpel tunnel and trigger finger. The Rival-X is much lighter in roll than I was used to, but after 2hrs of flying and 100 landings in calm conditions, I had this wing figured out. Now with about 12 hours on the wing, I feel fully transitioned and don't feel like I am in test pilot mode anymore. Before deciding on this wing, I took a demo flight with Larry with his Rival-S and with a local pilot on his Rival-X wing to make sure I would be happy with the handing of this ring. Larry gave me a "roll dampener" for the wing. It is an adjustable dashpot device that is mounted between a downtube and the hang block. The roll dampener resists abrupt changes to the control bar position in roll from gusts or pilot input. It helps keep the pilot from creating any pilot induced oscillations (PIO). I like it but could see removing it in the future. The handing in pitch is light, with a recognizable, stable hands off trim spot where there is no forward or aft pitch pressure.

    The 14.0-meter wing area gives me extra lift to fly slow and efficiently to save gas on long XC flights. The 1160 lbs. GTOW capability would mean I could fill the gas tank when I take a heavy passenger for a ride. The wing has vortex generators along the leading edge of the center of the wing and they work fantastic. I cannot get this wing to stall in level flight. I'm sure I could whip stall it, but don't really want to. Control bar all the way out to the nose tube, I read 35-37 mph indicated airspeed. Other wings I have flown would get very stiff and hard to turn and then start to "buck" in my hands as I approached stall. The Rival-X just slows down and remains controllable at low speeds. My wing originally had a hands off trim speed of 55mph. Since the wing was so well behaved at 37 mph, I adjusted the variable trim cables by a half inch to shift the slow trim, hands off trim speed to 45mph indicated. That way I can pull in just a little to fly at 50 mph for my approach for a landing, then let the bar float out to trim for the round out, and pushout to keep the nose wheel up on landing. I can also let the bar float, trimmed at 45 mph to climb too. If I want to cruise faster at 55 or 60mph, I'll just use the variable trim system to increase the hands off time speed.

    On the high-speed side, I have made it to 75 mph indicated in sustained level flight at 6000 ft MSL with my Rotax 912-80HP engine spinning at 5600 RPM. Not sure I'll do much flying there because I am burning 5 gallons per hour, but I occasionally need that extra speed capability to battle 30-40 mph headwinds. No high-speed dives yet. I might be able to get to 80 mph in level flight, but I'll be at maxed out at 5800 RPM, not a sustainable condition. This is more a limit of my 80HP engine at this altitude, and not due to the wing.

    The wing flies perfectly straight, hands off at low speed. At higher speeds, the wing wants to strongly turn to the left. The roll input required is too much to comfortably fly and hold for very long. Larry gave me a small fixed angle trim tab to stick on my wheel pant that cancels most the turn at high speed. The trim tab reduces the required high-speed roll input by around 80%. I can live with that. I'll probably fiddle around with the trim tab to get it perfect, but this is definitely a good simple solution to the problem. My hangar buddy Paul has exactly the same problem at high speeds on his Profi wing and he has the same solution.

    The variable trim to shift the hang point works great. It is an interesting design, not one I had seen before. The actuator is mounted on the keel, under the nose and has a pair of cables that run down the keel to the hang point block, which has a round bearing that the keel slides through. When the trim is set to slow, the actuator is all the way out, the wing is pulled back by drag until the cables are in tension. To shift the hang point forward and trim at a faster speed, the actuator pulls the ends of the cables forward, which to pulls the hang point forward, sliding it on the keel through the bearing. There are some safety bolts on the keel that limit the range of motion for the hang point. It took me a while to figure it out, but works great, and is light weight, small and easy to adjust.

    Larry was able to ship it the wing long packed to my hangar at Belen, NM. He was a great help with my questions while setting it up for flight. Again, I am very pleased with this wing and look forwards to a lot of fun hours of flying on it.
  • Frank Dempsey
    by Frank Dempsey 11 days ago
    Awesome Jeff. It's a good looking wing too. I need to fly with you soon. I took my Profi w/out the wing tips out yesterday to play around in high wind. The Double Eagle tower now has radar. I was in the downwind and the tower reported my groundspeed at 80 knots (about 90 mph) hands off which agreed with my GPS. On the next downwind I pulled in to get an airspeed of about 75 mph and a groundspeed reading of 106 mph. The air was smooth.
  • Rizwan Bukhari
    by Rizwan Bukhari 10 days ago
    Jeff,

    That wing is such a beautiful match for your trike. Very nice review as well. How many hours do you have on your 912 now? You said that when you push the control bar all the way forward to the nose tube it flies at 35-37. So does it stall around at 35 mph too.

    So other than the lighter handling in role, how else do you see a difference between a Profi wing and this Rival X wing? Any input would be greatly appreciated.
  • jeff trike
    by jeff trike 10 days ago
    Rizwan,
    This is the 3rd engine (rotax 503, 912, 912) and the 3rd wing (Stream, Nuvix, Rival-X) on my trike. The engine is at 315 hrs, the Cobra chassis has 1824 hrs of engine running from a combination of flight time plus taxiing, warm-ups, carb syncs, prop pitching etc. The flight time on the Cobra is around 1680 hrs.

    The slowest I could get the Cobra/Rival-X to fly in level flight was 37 mph indicated airspeed. I was throttled back and the engine speed was around 3800 RPM. The control bar about a half inch short of touching the nose tube. I could maintain 37 mph in level flight. If I pushed the control bar to the nose tube and increased the angle of attack slightly, the wing would not generate any additional lift, but the drag increased, slowing the airspeed to 35 mph. The slower airspeed caused the trike to descend, reducing the angle of attack and increasing airspeed back to around 37 or 38 mph, then it would level out, slow down to 35 and repeat, slowly stair stepping down in altitude. Since the wing lift did not increase when I moved the control bar from a half inch from the nose, to the nose, I was at the max lift angle of attack, technically flying at stall.

    Wikipedia stall - "In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases."

    So that’s why I said my stall speed was between 35 and 37 mph. I had a full tank of gas (126 lbs) at the time. If I only had a gallon or two in the tank I could have flown slower. I’ll probably try that someday. Stall speed depends on weight too. The Rival-X documentation says 38mph at GTOW (1160 lbs.)

    However, there was no dramatic decrease in lift, no separated flow, no roll off to the side, no bottom dropping out, free fall, etc. A very gentle and controllable stall. This was due to the VGs (vortex generators) keeping the airflow attached at the center of the wing and the light roll handing of the wing. The wing remained very stable and controllable in roll. It was stable in pitch, but since I was maxed out with the control bar against the nose tube, I did not have any real pitch control and would not want to land that way. When I land, I level out about a foot above the runway with no power, then let drag slow the trike down in ground effect while slowly pushing the control bar out to maintain lift and the one foot ground clearance. When the control bar approaches the nose tube, I can’t maintain lift anymore and mains will touch down. Then I can wheelie it for a while to slow down even more before slowly pulling in to let the nose touch down gently.

    As far as comparisons to the Profi, the Rival-X lighter handing in roll and low speed handing in general is the main advantage. That is why I went for the Rival-X. I think the Profi might be able to go faster. It is difficult for me to make this comparison, because the only Profi’s I have flown or are nearby are on 912-S 100 Hp engines. My hangar buddy Paul said when he put the wing tips on his Profi, he picked up an additional “free” 10 mph. So I expect he has 10mph on me, plus whatever he can force with his extra 20 HP.
  • Paul Hamilton
    by Paul Hamilton 8 days ago
    Jeff, nice perspective coming from an experienced pilot like you. I love that 4 inches of trim slow to fast. The more you fly it the more you will love it. I find flying in turbulence much easier with the better handling wings. Once you fly a well behaved wing such as the Rival it would be hard to go back to a stiff wing but I am forced to during training in others trikes. One tip is to slow it up to about half trim in turbulence. Enjoy.
  • Larry  Mednick
    by Larry Mednick 8 days ago
    The Profi is more efficient. It is in fact one of the most efficient wings ever made. The RIVAL wings are designed for optimal handling especially at slow speed. However the RIVAL can be adjusted to increase performance just by adding in a 3/8” shim on each Wing tip. I personally hate optimizing performance while diminishing the handling of a Wing. Therefore we try to get something like 100% handling and 90% performance. The alternative is something like 100% performance and 60% handling.
  • Douglas  Lee
    by Douglas Lee 8 days ago
    Is the Rival-X built by Northwing?
  • Larry  Mednick
    by Larry Mednick 8 days ago
    Yes, 95% of it.
  • Rizwan Bukhari
    by Rizwan Bukhari 7 days ago
    Jeff,

    Thanks for taking time to explain the differences. This will help many out there researching for a new wing. I look forward to your adventures in your new wing.

    Safe landings :D
  • Rizwan Bukhari
    by Rizwan Bukhari 7 days ago
    Thanks Larry, you are always helpful. I appreciate it
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