Aircraft rigging anyone ever fly a Flaglor scooter out there?

Discussion in 'General Experimental Aviation Questions' started by buzzypeterson, Aug 27, 2012.

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  1. Aug 27, 2012 #1

    buzzypeterson

    buzzypeterson

    buzzypeterson

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    Hey guys, I have 2 flights in in the flaglor scooter. She needs some tweeking but i'm not sure what to tweek. the first flight the prop had to much pitch and RPM's were low so I thought maybe just changing the prop would fix all our woes. The second flight with a flater prop the takeoff roll was better but when I pull power the nose drops fast... a glide is more of a dive but when I add power she will flatten out.

    We are within CG but certainly toward the forward of the limit. She did get a little heavier when we rebuilt her, we are weighing in at 495 if my memory serves me right. The weight mainly came from beefed up landing gear and cub wheels and brakes. I know our wheels are quite a bit larger than the original so maybe drag is an issue? We are using a 1600 VW versus the 1200 that was originally on her. around 10 more pounds put quite a bit more snot.

    In flight she climbs slower but is acceptable and probably as advertised at 450 fpm maybe a little better. Once I level off at full throttle she will fly fine but anything less than full and she seems to loose altitude in a level attitude, and even if I pitch up she just comes down unless I add power. Any ideas? or is this maybe just how a flaglor flies?
     
  2. Aug 27, 2012 #2

    bmcj

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    Never flew a Flaglor Scooter... the ugly factor never let me get close enough to try it. :gig:
     
  3. Aug 27, 2012 #3

    revkev6

    revkev6

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    did you change any of the engine mount dimensions?? with an engine mounted that high it's angle is very important to flight characteristics.
     
  4. Aug 27, 2012 #4

    Joe Fisher

    Joe Fisher

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    It sounds to me like a hole lot of drag. Some wing wash out will reduce drag.
     
  5. Aug 28, 2012 #5

    pwood66889

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    "The second flight with a flatter prop the takeoff roll was better but when I pull power the nose drops fast."
    For those who never saw the Flaglor, it is an interesting beast. The vw engine is mounted tractor fashion above the wing and in front of the wind screen. The thrust line is Very High, so that would happen when "Power is Pulled."
    So it sounds like the original configuration had smaller power so the high trrust line flaw did not appear. Upping the horse caused problems. Suggest you look at engine cant to the air frame.
    Percy in SE Bama
     
  6. Aug 28, 2012 #6

    buzzypeterson

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  7. Aug 28, 2012 #7

    buzzypeterson

    buzzypeterson

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    You know the thought of the prop blast has crossed my mind. But in the challenger ultralight I flew having high thrust actually causes the opposite. When you pull throttle back it noses up. But I never thought the larger engine might from full power to idle be a larger difference that is a neat observation.

    I don't think that is the only thing going on though because she doesn't pick up speed and then level off after it picks up speed. It's like it will keep on a diving till I add power. The weight of the engine is within 10 pounds of the old 1200cc it's just a larger bore cylinder.
     
  8. Aug 28, 2012 #8

    Dana

    Dana

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    Mod note: Thread moved to the general area because it's not really a "tube and fabric" discussion.
     
  9. Aug 28, 2012 #9

    Autodidact

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    Since the pilot is a similar weight to the engine, I would guess that the CG is located vertically below the thrust line by roughly 2.0 ft or so. With power on, the thrust acting on the center of mass (CG) through this 2.0 ft moment arm would be the dominant factor affecting the pitching moment about the CG, with power off - and all other things equal, except the longitudinal location of the CG - the fore/aft location of the CG would be the dominant factor affecting the pitching moment.

    Also remember that the tailplane is in the prop's slipstream and the velocity is different with power-on than power-off. If the tailplane is set so that the power-on slipstream acting on the tail plane cancels out the moment created by the thrust times the moment arm above the CG, then with power off, it could be the forward CG location.

    "Pulling power" is to take the power away?

    You also have the heavier/bigger wheels which is more weight forward and more drag down low. I'd try a lower drag gear and if that helps then try the cruise prop again.

    How much speed do you gain when you level off after the climb?
     
    Last edited: Aug 28, 2012
  10. Aug 28, 2012 #10

    buzzypeterson

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    yes what I mean by pulling power is to reduce throttle. I know most airplanes will nose down when you reduce throttle then pick up speed and shallow out. This thing is basically a full on nose dive. and when i'm coming in there isn't much elevator there to flare unless i'm coming in under power... then there still isn't a ton of elevator but at least the vertical speed is slow.

    Yeah the tires are going, that is a done deal! As far as the weight though the gear are actually just aft of the CG, but the drag isn't helping in the least. She gets upwards of 75 miles an hour flat out.. climb is in the 60's. I haven't ever flown anything with just wires maybe it is just that draggy?
     
  11. Aug 28, 2012 #11

    Autodidact

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    dblpst
     
    Last edited: Aug 28, 2012
  12. Aug 28, 2012 #12

    Autodidact

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    Are you sure you haven't made a miscalculation here? :) If it is a tail-dragger, and the gear is aft of the CG, it would tip onto its nose. Or is this the measurement without the pilot? But, looking at this picture, I don't see how it is possible:

    flaglor-skyscooter.jpg
     
  13. Aug 28, 2012 #13

    Autodidact

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    Measure back from the wing leading edge a distance equal to 25% of the distance from the leading edge of the wing to the trailing edge; your CG should be very close to that point.
     
  14. Aug 28, 2012 #14

    revkev6

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    I don't know what the specs are supposed to be on this aircraft but the higher above your engine is above the vertical cg the more the engines need to be angled "up" to counteract the pitch down tendency of the thrust line. if the engine install was changed is there a possibility that the angle was increased more than the specified amount?? a high angle like that could also push air down on the elevator....

    I have run into exactly this on model aircraft that I have experimented with high thrust lines. you have to fine tune the thrust line to get the planes pitching moment correct with throttle.

    edit: autoaddict is right, take another look at your cg and when you are absolutely sure you have it correct, find someone else to verify it!
     
  15. Aug 28, 2012 #15

    Joe Fisher

    Joe Fisher

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    That airplane is a primary glider with an engine. It should glide just fine no matter what angle the engine is set at. The drag of the Cub wheels is negligible at less than 80 mph.
     
  16. Aug 29, 2012 #16

    Autodidact

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    This is a bad situation - CG too far forward. Buzzy, you should not fly it; if you lose the engine, how will you flare for landing?
     
  17. Aug 29, 2012 #17

    timberwolf8199

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    Note of clarification: it needs to be angled up if it is above and in front of the cg. it needs to be angled down if it's above and behind.
     
  18. Aug 30, 2012 #18

    buzzypeterson

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    You know, you guys are right. The CG is in back of the gear. I wasn't thinking right. We used the leading edge as a datum and I got mixed up. Looking at the numbers I am 215 pounds by the time I get in the plane... unless I fly naked and without shoes (probably won't be welcome at to many fly ins that way). We figured the CG with 200 pound pilot and it was right up at the nose heavy limit. I guess the extra 15 pounds even though it isn't a gigantic arm puts it over.

    Down the line I will make the fuel tank in the nose smaller and do something lighter for landing gear. But for now i'm adding a pound or two to the tail. I will let you guys know how it goes when we have some junk in the trunk.

    Thanks for your input!
     
  19. Aug 30, 2012 #19

    Dan Thomas

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    Probably the stabilizer angle is off. Angled down too much. When the prop blast disappears, the tail normally loses downforce and the nose will drop. If the stab angle is too much down, the elevator will be trimmed downward to counter the stab, and that will aggravate the dive in power-off situations. The forward CG won't be helping, either.

    Dan
     
  20. Sep 2, 2012 #20

    Turd Ferguson

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    When flying straight and level under power, what is the position of the elevator? Then, same question when gliding power-off?
     

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