Why won't my Horten 229 fly!?

[OlegTheMeerkat]

I have built a House 229 but it simply won't fly. Is the CoM and CoL correct? When it gets in the air it acts as if it wants to fly in the opposite direction. Help

Spoiler

Spoiler

Spoiler

Spoiler

 

 

 

 

 

[Rocket In My Pocket]

Could be an issue with the stock COL display.

I use and recommend:

 

[Spricigo]

32 minutes ago, Rocket In My Pocket said:

Could be an issue with the stock COL display.

Yep, the issue of it not being Center of Drag and it not telling how the aerodynamics forces change as point your craft away from the airflow.

Also CoM shifting with fuel consumption may also be an issue. So lets add another mod suggestion:

 

[Zeiss Ikon]

For a tailless or flying wing design, you need to have the COM a little further forward and design in either twist in the wing or preset up elevon to raise the nose against the nose-down moment of COM ahead of COL.  Using elevon or wing twist this way ensures that as speed increases, the nose will rise, and as speed decreases, the nose will drop, making the craft what model airplane designers call "longitudinally stable."

The other issue with this and a couple other Horten designs is that without a vertical fin, you're going to have huge issues with adverse yaw -- that is, when you apply aileron (elevon) for roll, the down-going wing will want to fly faster and the up-going wing will want to slow down -- which is exactly opposite the direction you're planning to turn.  One way to work around this is to couple spoilers to the roll control channel; they'll lower a wing while adding drag, instead of reducing it.  Combine those with reduced roll throw on the elevons, and you can get a yaw-neutral roll, or even a little proverse yaw if you like feeling as  if you ailerons and rudder are coupled (like in an original Ercoupe).  It's possible to use spoilers alone for roll, but you'll get a lot of proverse yaw, probably enough to make you think the aircraft is handling badly.  Combining the spoilers with aileron (or elevon roll), and having adjustment for the roll authority in the ailerons or elevons, gives the best of both worlds.

Edited October 27, 2017 by Zeiss Ikon

[Scarecrow]

I built one of those too.  I managed to get it to fly fine, though the pitch response was a bit sluggish.  What I had problems with was getting the damn thing to track straight down the runway.  I really had problems getting it to build up enough speed to take off before it veered off in an uncontrollable mad dash for the scenery.

 

 

Edited October 30, 2017 by Scarecrow