I keep on breaking props! pls help (videos inc) - RC Groups
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Oct 06, 2017, 09:36 AM
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Help!

I keep on breaking props! pls help (videos inc)


So I was following this guide (https://www.instructables.com/id/Com...-DIY-RC-Foamb/) to build my first RC plane. It's got a 1400KV motor powered by 3s lipo, 9*5 props and weights about 470 grams with everything in it. But i'm failing miserably at my every attempt to fly it.

Here is the video -
crashing rc plane (0 min 6 sec)
- where tried to take off it but it rolls hard right and crashes on the nose. I broke 3 props that day while trying to take off the plane. Sorry about the quality of the video, they look dark as it was during the late afternoon. I think i had the full up elevator for this one and maybe that's the reason?

Today I tried again to hand launch (instead of taking off) it against the wind (there was a bit of wind as well). I pushed it towards the wind with 3/4 throttle, but i felt like it was carried by the wing, rolled to right and a nasty crash again. Everything lasted for about 2-3 seconds, video -
hand launching rc plane crashing nose down (0 min 3 sec)
.

I dont know why it's rolling towards its right? could that be due to airfoils not being symmetrical? Also does it look like it is nose heavy?

it breaks my heart to see that i keep on breaking props even without getting the plane properly up in the air but i'm determined to get this thing flying!

I will do a glide test tomorrow and see.

Any suggestions as to why it's happening so? i will post this on crash discussions and electric plane talk as well. Much thanks!
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Oct 07, 2017, 05:17 PM
Registered User
It looks terribly tail heavy. It should balance about 1/3 of the width of the wing behind the leading edge of the wing. Also try it with half throttle. It will give you more time to think, and won't hit as hard. Be ready to take off the throttle immediately too. Maybe it could use some down trim too, it is hard to tell without being there. On that plane you could just throw it forward to test glide it too. No motor power at all. It is pretty much a glider, with a motor.
Oct 07, 2017, 05:22 PM
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pmackenzie's Avatar
First video you have too much up elevator.

As mentioned above, check the CG.

If you have never flown before then the type of model you made is not the best to learn with. No dihedral means that it has very little inherent stability.
Oct 11, 2017, 06:55 PM
I miss President Reagan
KMK001's Avatar
Verify ALL controls move in the direction they should!

Check for wing warp/twist. Easiest way is to take two pieces of balsa sticks, 3/16 x 3/16 square or similar. And rubber band or tape them to the underside of each wing tip with the majority of the stick out in front of the wing. Then look from the side. Both sticks should point at the same angle. I suspect the left one will point higher than the right effectively giving you a lot of right aileron.
Oct 12, 2017, 08:20 AM
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Cougar429's Avatar
Flights are far too short to see if it is the plane or pilot.

First recommendations would be to have someone more experienced in your area have a look at it. Your construction, (incidence) balance or control throws could be way off.

They could also perhaps do a test flight to get it trimmed out or tell you if something wrong so you can at least expect it to behave reliably.

I have been instructing for far too long and one of the first instincts when things go loopy for low time pilots is to yank back on the stick. One of the most difficult habits to break sometimes. A trainer should be designed, built and set up to stabilize itself if control inputs are released.

Lastly, grab a PC based flight sim and practice.
Oct 12, 2017, 03:41 PM
Registered User
Here is second thread started by the original poster presenting the same issue and with many more responses:

https://www.rcgroups.com/forums/show...0#post38414785

I agree with responses on the other thread: an aileron/elevator/throttle, no dihedral plane being attempted by a beginner in wind is not a winning setup. Don't be discouraged but perhaps set this plane aside for now and start with an elevator/rudder/throttle with dihedral model of similar weight/construction in a no wind to virtually no wind situation.

Michael in Ontario, Canada


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