burrito inverted

2470 Views 51 Replies 19 Participants Last post by Gordo, Oct 23, 2004

edge540flyer

Discussion Starter · Oct 21, 2004

what would cause my burrito to push realy hard to the left inverted but fly great up right and in up lines I have to hold a lot of left rudder for stright when inverted.
thanks
Brandon

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Spaz

· #2 · Oct 21, 2004

something is warped or not set neutral
right rudder, bent fuse, ailerons are warped and not set neutral...
plus check your latteral ballance is the batt on the same or opposit side as the engine, add 0.5 oz to the left wing tip and see if its better, you can hang the model from a string to check lateral balance attach the string to the fuse at the nose and the tail,
do you have about 2degress of right thrust?

edge540flyer

Discussion Starter · #3 · Oct 21, 2004

battery is opposite of the motor i have right thrust and will check lateral balance. thanks for the suggestions
Brandon

kirkman

· #4 · Oct 21, 2004

What prop engine you using? that could do it..

PaulSwany

· #5 · Oct 21, 2004

Okay.... Here's what I'm thinking.... If you have some right thrust built in... that works great when you model is upright, cause you're offsetting the torque of the engine is pulling to the left...

However... When you're inverted.... the torque of the engine is still wanting to pull left.. but now your engine has left thrust which makes the problem worse....

I always seem to have to ride the rudder when I'm inverted...

edge540flyer

Discussion Starter · #6 · Oct 21, 2004

using an evolution .46 with apc 11.5x4. paul how many washers do you use for right thrust you think two may be to many?
Brandon

PaulSwany

· #7 · Oct 21, 2004

I use either 1 or 2 washers depending on how she flys... I have two in my MoJo right now and that's 1 too many... I'm gonna drop it to 1 and see how she does... I'm constantly feeding left rudder in a TR....

You might drop it to just one and see if that improves inverted flight..

2FAST4U

· #8 · Oct 21, 2004

Sorry, I have a hard time buying that Paul. The "P" factor is the effect that we are talking about here. The engine is offsetting the "P" factor no matter which way the plane is pointing. Let me explain....

Upright....Engine pulls (torques) the fuse to the "left side of the plane", right thrust counters that effect.

Inverted....Engine pulls (torques) the fuse to the "left side of the plane" and the engine offset still counters that. The plane is now going a different direction "on the ground", but not with respect to the plane it's self.

It could end up being more of a factor of balance, trim, orientation, or something else, but I don't think it's the engine offset. I would tend to think it's closer to being due to the engine thrust line (possitive/negetive) causing a change in the overall trim condition when inverted.

That's about all the extreme wisdom I can puke up right now. :shock:

Spaz

· #9 · Oct 21, 2004

wow, Paul you got Rocked

dhooks

· #10 · Oct 21, 2004

Stay tuned for the next addition. Didnt this get discussed in the inverted harrier thread?

georgec

· #11 · Oct 22, 2004

I also had two washers on my Burrito. I took one out and it flys a hole lot better. All the rest of my profiles have two.

Gordo

· #12 · Oct 22, 2004

I had a post written out earlier this afternoon, then thought more about it and realized I confused my self silly :roll: Not hard to do.

Oh hell, forget it. I just wrote 5 paragraphs and couldn't make it make sense. I believe the situation is a result of p-factor and slipstream. The fact is that TO THE PLANE the inverted harrier is a NEGATIVE AOA and reverses the p-factor. It makes sense in my head, but I can't get the thing down on paper!!

Gordo

· #13 · Oct 22, 2004

To further complicate this, have you considered the consequence of have a reverse running engine and a pusher prop? I'd like to try it one time.

dhooks

· #14 · Oct 22, 2004

Man Gordo I havent got the regular setup figured out an your into reversed engines?

edge540flyer

Discussion Starter · #15 · Oct 22, 2004

looked at the plane a little closer today and looks like my lateral balance was off a bit took one washer out and looked everything over to check for warps (found a few)
hopefully this takes car of most of the problem it just seems holding half left rudder while inverted is a bit much. maybe it is just getting used to a new plane.
Brandon

BIZZARO

· #16 · Oct 22, 2004

I thought the only thing that P-FACTOR affected was wether or not you had another plane to fly incase you crashed the one you were doing inverted harriers with...Ohhh P-FACTOR means something besides pucker factor..My BAD...

2FAST4U

· #17 · Oct 22, 2004

spastic said:
wow, Paul you got Rocked

NOT AT ALL!!!! I wouldn't "ROCK" Paul, he's my favorite nizzel. :lol:

I'm in the same boat as GORDO, I know what I mean, I just can't put it into words very well.

PaulSwany

· #18 · Oct 22, 2004

Talk to me some more about "P" Factor... I always thought that it was the gyroscopic force caused from the rotating mass of the engine..... If that's true.. then the force would be constant in one direction. The rudder on the other had steers one way upright and the otherway inverted. So that seems to me that the right thrust set to compensate for "P" factor would be correct upright and incorrect when inverted.....

Help me understand you're point of view...

Spaz

· #19 · Oct 22, 2004

p factor or propellor factor is the result of the airstream meeting the prop at an angle other than head on or 0deg to the thrust line, for example on takeoff the plan is at an angle to the ground because of the gear so the right side of the prop disk sees the air at a higher angle of attack then the left side of the prop disk so the right side of the disk is pullin harder than the left, hard to explain without drawings, i could probably dig up some shit if you want.
here is one article from dj aerotech
http://www.djaerotech.com/dj_askjd/dj_questions/propeffects.html

2FAST4U

· #20 · Oct 22, 2004

P-Factor is caused by the air comming from the prop that is flowing down the fuse, interacting with the plane. As it rotates around the fuse, it strikes the upper portion of the tail, pushing it to the right. This pushes the nose of the plane to the left. You can find this effect on any prop plane, except a pusher configuration.

The Russian Yak planes, run a radial engine. The engine is geared and turns the prop in the opposit direction (counter clockwise from the pilot's view) and causes them to hold "LEFT" rudder when taking off instead of right rudder.

Torque is a different force in the mix. Torque causes the plane to want to roll to the left. As the engine spins the prop, the only leverage the engine has is the plane it's self. So as you Hammer the throttle 2 thing happen.... 1) P-Factor pulls the nose to the "LEFT SIDE OF THE PLANE" and 2) TORQUE IS TRYING TO ROLL THE PLANE in the opposit direction of the prop.

If you have flown long enough, and I know you have, then you have seen these 2 forces at work. How many times have you seen this happen...... A person gets into a bad spot, he hits the throttle and then he SNAPS the plane into the ground. P-Factor pulls the nose to one side and Torque rolls the plane to one side, all at once. The pilot says things like "I don't know what happened, I gassed it and it snapped out on me.

Don't get me wrong, I'M NO ROCKET SCIENTIST and I'M NOT TRYING TO BE A KNOW IT ALL!!!!!!!! I'm just trying to shed some light on the problem. I hope I have not confused anyone, and I'm not looking to get into an argument about all this. Heck, I could be wrong, but having been raised by a comercial pilot and been flying full scale since the age of 9, I do know a little something about this stuff.

Hope this helps some.

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