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Old Nov 07, 2012, 11:36 AM
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Heiner,
Interesting flight, im assuming all if the yaw instability was caused by the nose gear moving?

I remember seeing a video of a fairly large EDF horten without extensions taking off and getting about 50-100' off the ground before entering a spin to the right (im assuming due to the lack of extensions).

Have you guys seen that video? If so, do you have a link? I could of sworn i saves it when i saw it, but it has been mia
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Old Nov 07, 2012, 11:59 AM
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Yes the instability came from the front wheel. With all wheels in, she is doing fine, because it's my Ho-IX

The other Ho-IX what went in after 100 feet is from my friend Ralf. I made that short video a few years ago, I will check if I saved at my computer.

Ralfs Ho-IX went in, because the was tail heavy and no tube extensions.

Heiner
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Old Nov 07, 2012, 12:01 PM
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Heiner,
Good to hear they are doing well, hopefully the CG on ours works ours works out to be at the same position as the smaller 82" version
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Old Nov 07, 2012, 12:33 PM
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Horten 229V3 crash (0 min 24 sec)


here we go!

Tail heavy and no tube extension!

Ralf fixed the Ho-229 after that crash, she is also doing fine now. He made up to 50 flights or more.

Heiner
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Old Nov 07, 2012, 12:41 PM
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That is the one! It didnt look like it took allot of damage in the video, but im sure it was more involved than it appeared.

Watching that video, really looks ver similar to multi engine airplanes that have the right engine inop and when they get to slow, they yaw and the flip inverted due to the assymetric thrust and drag. I bet since the edfs rotate the same direction, once the airspeed gets to slow it causes a large induced drag difference between the left and right, which is what causes the instability.
I say all that, bc ralfs appeared to be stable in yaw until the nose was pitched up for a steeper climb, then after a few seconds, the instability reared its head.
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Old Nov 07, 2012, 12:54 PM
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We studied that video picture by picture, the instability starts when he tried to go in a left turn! By lifting the left aileron the Ho-229 moved to the right and flipped over.

Heiner
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Old Nov 07, 2012, 12:56 PM
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Aaahhhh ok,
That is one thing i couldnt tell from the video. So the turn caused the stability, interesting, as that just made it more complicated!
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Old Nov 07, 2012, 01:15 PM
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To make a turn possible, you have to program a lot of differential. If you try it symmetrical, aileron movement up = down, then the Ho-229 is not turning she keeps on going straight.

Heiner
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Old Nov 07, 2012, 03:21 PM
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Heiner did his Ho use the frieze ailerons?
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Old Nov 07, 2012, 03:32 PM
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United States, CA, Cameron Park
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That's a very good question! The twist would also make a difference. I've generally used a BSLD (sin cube) on my Hortens and they turn well with just plain elevons and no differential.

Disclaimer--your results may vary.

Brian
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Old Nov 07, 2012, 04:33 PM
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@ turbonut,

no just plain ailerons not frieze type. If you just have 2 ailerons frieze type once would deliver too much drag as an elevator. If you organized a 4 or 6 flap arrangement then friesze type ailerons are the best.

Heiner
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Old Nov 07, 2012, 08:44 PM
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ok, that also explains some of the yaw problem with that plane
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Old Nov 08, 2012, 11:04 AM
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I've built a few pure wing sailplanes in the past. If they were too tail heavy, they would happily turn sideways and crash exactly like the video, and this was without any edf's or tubes to blame it on. I had a 3m span one that was about 60 seconds into a flight when this happened. It seemed to be flying fine and then it just wasn't. I had trouble with spins on winch launches too. Some guys in Germany found that certain tip airfoils would keep the spins away.

Another one I made had too much twist in it and needed a lot of nose weight to get it flying without down trim. It wouldn't go very fast, but it ended up very stable this way. It was supposed to be a 1.5m slope racer, so a failure on that, but I learned something.

It's reasonable to assume that these Horten models have not all been built and set up the same, so I wouldn't expect the same behavior just because they look similar.
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Last edited by Steve C; Nov 08, 2012 at 11:18 AM.
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Old Nov 08, 2012, 11:05 AM
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Steve,
That is some very interesting information! Also makes ya go "hmmm" just a little bit more
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Old Nov 08, 2012, 11:26 AM
right between the batteries
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Farmington UT
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the guys at CrashTestHobby say it repeatedly that flying wings will NOT fly tail heavy... i can understand how the edf's mixed into the equation over the tail of the wing would only agrivate the issue.

good info! thanx for the video
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