Simple Cub; Thrust angle for motor

[alan0043]

Hi Everyone,

I have a few questions about thrust angle on the motor. I have a simple cub that I built from a speed build kit. Earlier this summer I flew the plane had a few crashes because of being a rookie. I had to repair the plane by putting in a new power pod. Now the plane does not want to take off and all it wants to do is make left turns. I have checked the landing gear to make sure that the wheels are tracking straight. One of the real experienced pilots at the field said the plane should have some thrust angle on the motor. If you are looking from the back of the plane looking forward the motor should point down and to the right. Any thoughts ? I understand I can use washers behind the motor mound to make an angle change.

 

[Monte.C]

Yup a little down and a little right. I can't remember the angles I use! I think it's 2-3 degrees down, 4 degrees right, as a starting point. I have notes at home.
You could also shim with little pieces of credit card, drilled for the motor bolts.

 

[Monte.C]

But if your plane refuses to lift off the ground, down thrust sure won't fix that. Does sound like you need right thrust though.

 

[alan0043]

Yup a little down and a little right. I can't remember the angles I use! I think it's 2-3 degrees down, 4 degrees right, as a starting point. I have notes at home.
You could also shim with little pieces of credit card, drilled for the motor bolts.

Hey Monte,

Thank you for the idea about using a credit card for shims.

 

[Flyingshark]

Hey Monte,

Thank you for the idea about using a credit card for shims.

Ideally it should be one you don't use anymore.

 

[Monte.C]

2-3 degrees right, 4-5 degrees down. found my note. This is round about where I start, have used this on several planes and never needed to adjust it.

 

[Monte.C]

Ideally it should be one you don't use anymore.

See you guys! I'm not the only knucklehead around here.

I've never used shims but if you do you might need to get creative. Maybe split the difference and go 3 and 3 degrees. I mean because you'll maybe use no shim on one screw, 2 shims on the opposite screw and one shim on each of the two middle ones. Anyway you'll trim the plane once it's in the air, that'll refine it the way you need.

Caution: Don't use an active credit card. The secret magnetic/electronic stuff inside it might interfere with your receiver. And once you cut it it'll let magnetism and electrons out and stuff.

 

[Flyingshark]

See you guys! I'm not the only knucklehead around here.

I've never used shims but if you do you might need to get creative. Maybe split the difference and go 3 and 3 degrees. I mean because you'll maybe use no shim on one screw, 2 shims on the opposite screw and one shim on each of the two middle ones. Anyway you'll trim the plane once it's in the air, that'll refine it the way you need.

Caution: Don't use an active credit card. The secret magnetic/electronic stuff inside it might interfere with your receiver. And once you cut it it'll let magnetism and electrons out and stuff.

I think you can also use metal washers, if you're lucky enough to have some of the right size.

 

[TheFlyingBrit]

If you built the new powerpod from the plan, the angles will be set ?

 

[TheFlyingBrit]

sp0nz-plans-index.17136/

 

[The Hangar]

If you built the new powerpod from the plan, the angles will be set ?

The swappable pods done have any thrust angle on the plans.

 

[The Hangar]

Ideally it should be one you don't use anymore.

I can’t use any of mine any more, I’ve set up direct deposit to ft store and Horizon Hobby.

 

[alan0043]

If you built the new powerpod from the plan, the angles will be set ?

I always thought that the full size power pods were swappable. Maybe not.

 

[TheFlyingBrit]

Pulling strongly to one side can be a steering issue i.e. landing gear not straight it can be hard to see by eye you can usually tell when you taxi the plane slowly if its still veers off, your landing gear needs tweaking .
The other issue could be a torque issue, the motor will pull the plane to the right. In excessive cases the plane will continue to pull to the side even after take off, rudder is the usual correction.
If it doesn't want to take off, have you checked to see if there is enough thrust ? For example did you re-connect the motor the correct way around when you re-built the power pod ? is the prop turning the correct way ?

 

[TheFlyingBrit]

Sorry if I am teaching my Granny to suck eggs, but the other possible lack of power is the prop being put on back to front ?
These things may be custom and practice for most of us but some beginners don't appreciate realise the impact CW rotation versus CCW rotation of a prop whether its due to a motor in reverse or the prop on backwards.

 

[TheFlyingBrit]

I always thought that the full size power pods were swappable. Maybe not.

Most are suppose to be but I have found in most instances they are not, the lengths vary as well as where the mounting lugs are sighted. I always build to the plan that way I am 90% sure it will fit.

 

[TheFlyingBrit]

The swappable pods done have any thrust angle on the plans.

Thought I never saw any obvious thrust angles on the power pods, except for the Tiny Trainer and some of the mighty mini models I suspect.

 

[TheFlyingBrit]

Most are suppose to be but I have found in most instances they are not, the lengths vary as well as where the mounting lugs are sighted. I always build to the plan that way I am 90% sure it will fit.

Maybe they get modified slightly between updates ? If I built say a Spitfire version 1.0, an update 1.1 might have a slight change in the power pod design.
Good job I keep my original plans, that way I can use the same dimensions for repairs when I take copies from my plan.

 

[The Hangar]

Thought I never saw any obvious thrust angles on the power pods, except for the Tiny Trainer and some of the mighty mini models I suspect.

The minis do but the larger “swappable” planes don’t. Take the bushwacker and speedster for example, they have other mechanical changes to help counteract the torque roll but the pods themselves don’t have any built in thrust angle. The cub doesn’t have any built-in angle at all though.