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F-22 woes — some recommendations for my first scratch build?

#1
I've built my first scratch-build plane, the F-22 as seen in the Flite Test video. I did my best to follow along the instructions, and in the end made a nice-looking plane with working electronics....and it flies like a brick.

I set up velcro strips all along the nose to experiment with the CG, and just can't seem to get it to NOT nose-dive...even with the battery just in front of the motor (but on the underside of the fuselage). I can't really move the battery back any further than it is without mounting it towards the back of the plane and requiring additional extensions on the battery and ESC lines. And that just seems excessive.

I'm also having some unrelated structural issues with keeping things secure. I'm using posterboard from my LHS and it just doesn't offer a secure surface for mounting a motor mount to. Even super glue has failed.

A few questions:

  • Should my motor mount be a true 90º, or should there be a slight angle to give the plane more lift?
  • Have others out there (that have built the F-22) had CG issues? If so, what did you do?
  • What sorts of things can I do to secure the motor mount better to the wing? I'm having issues with insecure posterboard and even with packing tape reinforcement, I can't get it to stay put.

I'm not regretting the build one bit, and am still learning quite a bit from the process. But darnitall, I'd like to get this thing in the air.
 

Balu

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#2
I'm sorry I can't help you with your problems and that we are not supposed to do this, but Germany, Germany, ...! uhm, ok.

Did you use the heavy Kapa boards that most shops seem to have? What does the finished plane weigh?
 
#3
When you set your tail feathers (elevons) from the servo neutral postion trim center. Adjust the tail feathers about 1/8'' up from center? That way it has a smidge of up elevator. Then fly and trim from there.
 
#4
When you say it flies like a brick, do you mean it noses into the ground straight away? Or does it fly, just really badly?

It could be that you aren't getting enough airflow over the wings when you launch, have you tried just throwing it for a glide test? No motor, just throw it to a friend. It should glide pretty well with a decent throw. I suggest balancing the cg out to where it is on the plans first.

If this isn't helping try taking a video showing your setup and showing us it flies like a brick, this could help

Another thing, is the propeller on the correct way? It's an easy mistake to make, just check that the numbers on your prop are pointing towards the nose of your plane