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Blunt nose versa won't fly

Platon

Junior Member
#1
Hey,

I have a problem that is driving me mad. I recently finished building a blunt nosed versa (not kit, from scratch), but it won't fly!
I had to add very much dead weight in the nose to get the cg right. However, when I launch it, it just dives like it would if it was extremely nose heavy. I tried to remove all the added dead weight, but then it was extremely tail heavy.
What is causing this?

Thanks.
 

TEAJR66

Flite is good
Mentor
#2
Are your elevons level or do you have the required up reflex in them? I would go back to getting the CG correct, then add a few degrees of up in the elevons.

Be safe and have fun,
Tommy
 

Platon

Junior Member
#3
Are your elevons level or do you have the required up reflex in them? I would go back to getting the CG correct, then add a few degrees of up in the elevons.

Be safe and have fun,
Tommy
Yeah, my elevons are angled up a few degrees. The plane doesn't even fly when full up elevator, it just dives (and crashes).
 

TEAJR66

Flite is good
Mentor
#4
Sorry. Don't know what to tell you. Are you in tractor or pusher configuration? What power set up are you using? My first versa took three launch attempts to get sorted. I scrapped my one attempt at a blunt nose because it was too pitchy for my flying skills.

Be safe and have fun,
Tommy
 

Craftydan

Hostage Taker of Quads
Staff member
Moderator
Mentor
#5
Platon,

Are you using the CG marks on the outer wing or the blunt section?

Have you run a glide test? Even heavy this wing should glide well. If it does, but noses-in under power, you've got a thrust angle issue, and you'll need to put a shim on the motor (thin washer) to point it upward a touch.
 

Platon

Junior Member
#6
Sorry. Don't know what to tell you. Are you in tractor or pusher configuration? What power set up are you using? My first versa took three launch attempts to get sorted. I scrapped my one attempt at a blunt nose because it was too pitchy for my flying skills.

Be safe and have fun,
Tommy
It's a pusher. I am using a sunnysky v2216 900kv motor with a 10x4.7 slow fly prop. I think the cg points are wrong and it's way nose heavy.
 

Platon

Junior Member
#7
Platon,

Are you using the CG marks on the outer wing or the blunt section?

Have you run a glide test? Even heavy this wing should glide well. If it does, but noses-in under power, you've got a thrust angle issue, and you'll need to put a shim on the motor (thin washer) to point it upward a touch.
Glide test? Do you mean that I just throw it (without catching it again)? I have done that but I catched it after 1m and it flew, kind of. It dives a little. I tried to maiden it 2 days ago and it didn't go very well. The motor was angled upwards and I had the same problem, but then it flew (I still needed to give it full elevator or it would dive). Now the motor is parallel with the underside of the wing and now it won't fly at all.
And yes, I am using the cg marks/dots on the blunt section.

Thanks for helping me :)
 
Last edited:

Craftydan

Hostage Taker of Quads
Staff member
Moderator
Mentor
#8
If the airframe is trimmed out (reflex on a wing is typical, but usually all the trimming) you should be able to give it a hard toss and it should glide straight without input -- go ahead and pilot it down, as "how far" you have to move the sticks for the glide will tell you how far out of trim it is. Don't be gentle with the toss -- too light and it will stall before it settles into a glide.

Once you've got it trimmed where it will glide hands off, turn on a throttle hold (switch that prevents the motor from starting), set the throttle stick to 1/2, and give it a toss -- as soon as your fingers clear the prop, hit the hold switch and the motor should come to life (be prepared for the torque roll left ). If it dives, you need more upthrust. If it noses sharply up, you need more down. if all is right, it should start to climb before hitting the ground and you're off :)

for checking CG, creep the CG back once you've got it flying -- you'll know when it's staring to become tail heavy because the elevator trim will change with the airspeed -- the slower you go the more down you need, the faster the closer to neutral. nudge the CG forward again on the next flight and when you hit neutral, it should keep the same elevator trim regardless of the airspeed.
 

Platon

Junior Member
#9
If the airframe is trimmed out (reflex on a wing is typical, but usually all the trimming) you should be able to give it a hard toss and it should glide straight without input -- go ahead and pilot it down, as "how far" you have to move the sticks for the glide will tell you how far out of trim it is. Don't be gentle with the toss -- too light and it will stall before it settles into a glide.

Once you've got it trimmed where it will glide hands off, turn on a throttle hold (switch that prevents the motor from starting), set the throttle stick to 1/2, and give it a toss -- as soon as your fingers clear the prop, hit the hold switch and the motor should come to life (be prepared for the torque roll left ). If it dives, you need more upthrust. If it noses sharply up, you need more down. if all is right, it should start to climb before hitting the ground and you're off :)

for checking CG, creep the CG back once you've got it flying -- you'll know when it's staring to become tail heavy because the elevator trim will change with the airspeed -- the slower you go the more down you need, the faster the closer to neutral. nudge the CG forward again on the next flight and when you hit neutral, it should keep the same elevator trim regardless of the airspeed.
It fliew!
I added some elevator up trim, angled the motor upwards some degrees and removed some dead weight and it just fliew!
This time it flew much better than before. It was still a touch nose heavy so I landed it and removed some more weight and then it flew perfect.

Thanks everyone for the fast and helpful tips!