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Bushwhacker complete, on to a very wobbly modification...

Spacefarer

Active member
#1
It seems I'm going to be asking a lot of questions I wouldn't have imagined before. Each time I solve something another weirder problem shows up. Anyways, I have a tiny trainer that I want to turn into a twin engine. Only problem is, the wing mounted motors are INSANELY wobbly. I don't know if this is from the wing being mounted with rubber bands or the distance from the motor to the fuselage or something else, but the wobble is so intense that it actually made the aileron servos stop working while it was running. Should I try to put a balsa beam through the wing or something? If I need to glue it down I can, I made an access hatch for that purpose.
 

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Hai-Lee

Old and Bold RC PILOT
#2
It seems I'm going to be asking a lot of questions I wouldn't have imagined before. Each time I solve something another weirder problem shows up. Anyways, I have a tiny trainer that I want to turn into a twin engine. Only problem is, the wing mounted motors are INSANELY wobbly. I don't know if this is from the wing being mounted with rubber bands or the distance from the motor to the fuselage or something else, but the wobble is so intense that it actually made the aileron servos stop working while it was running. Should I try to put a balsa beam through the wing or something? If I need to glue it down I can, I made an access hatch for that purpose.
First thing I would try is to cut some blocks of FB to fit in the hole in the top of the fuselage, (snugly), and glue the blocks to the underside of the wing so that the wing will fit onto the fuselage with the blocks protruding into the fuselage. Done properly this will dampen down the wing fore/aft and sideways motions and the rubber bands will only be required to hold the wing down onto the fuselage.

In addition try to make the motor nacelles as close to the fuselage as the spinning propellers will allow, (leave a little clearance for safety!

Let me know how it works for you and if a further or additional solution is required.

As a guide here is a pic from a high speed advanced trainer that uses the locating blocks to firmly locate the wings in case the wing gets lifted during High "G" maneuvers.


SUNP0024.JPG

Have fun!
 

Spacefarer

Active member
#4
The motors both work fine, and the props I tested them with are balanced. I will try the locating blocks tomorrow and see how it turns out. Thanks!