Controllability trouble w/450

[wjcjr]

Got the new plane up today but not for long. The plane was pulling to the right VERY heavily. When reading below keep in mind; trims were good and CG I think is close.

This was my first flight with the 450. I retained the stock thrust angles and feel my problem is there.

First flight was with a 11X4.7 prop and lasted less than 15 seconds. Plane turned heavily to the right no matter what my input to offset and eventually the plane rolled over and did you know what. Damage was little more than a prop and a scuff on the wing center.

Second flight was with a 10X6 prop and the wing moved over to the left about 1/8 inch off of center. Reason I moved wing is the wing's CG is off a little. In the process of stiffening the wing I ended up with smidget more weight on the right side. The weight of a 6" pencil offsets this so it is not much of a weight discrepancy. I took off, considerably less thrust with this prop, the plane kept doing right hand circles but did not dive as last time. Although I know it would have if I did not have full left rudder inputted. The landing was miserable as you could guess and that prop is done along with a wing support, but the wing support is probably more visual than anything now anyway.

So I am concluding from this that my factory retained thrust angle needs to be turned to the left. Does this diagnosis seem sound? I was thinking about balancing the plane off somehow real lightly spooling up the prop with the current setting and see how much it pulls to the right, adjust angles and note affect. What do you think? Anyone else experience this with their 450 upgrades?

Thanks!

Wayne

Update... I moved the thrust angles to the left some and threw on the only other prop I have which is a STOUT 11X10. The torque rotates the plane to the left when plane is resting balanced out. I can not tell how the wash from prop is directing plane.

Atop this issue I just wrecked my aluminum spinner from e-flite. I think I tightened it too much and it has ceased. Grrrrr !!! I am having one of those days. I am sure it will get better. I also rethought the wing balance deal and am leaning toward getting some weights, anyone ever use those stick on weights or just impale a little weight into the foam with a dab of epoxy?

I will be eagerly awaiting your responses to this the latest of my adventure into RC flight.

Once again, Wayne

[SCC]

Sorry to hear your problems.

I have read a post by flyingmoose. And he uses the 450, 10 X 7 prop and 1500 9.6 batts.
And uses the stock thrust positions. I have not read that hes had ant problems.
Its all very strange

Hope you get it sorted soon.

[wjcjr]

Hmmm. I will keep plugging away. I am beginning to wonder more of my CG.
Before I say anymore I'll update this in the coming day or two with a result, one way or another !

[swampfox201]

Wayne,

I've been thinking of your post all day and to be honest I'm stumped. If your sitting in the thingypit (why wont this board let me spell thingypit --you know where the pilot sits) the prop is spinning clockwise right? I keep thinking of p-factor. If you had zero engine offset the greater the angle of attack the more right rudder you would have to add due to p-factor. I think this is the reason they mounted the motor in there at an angle to help counteract this. If for some reason your motor was turning counterclockwise then the motor offset would have to be the opposite direction than stock or the plane would want to turn right.

If you are able to get it up high see if the plane still wants to turn with zero throttle. If it doesn't turn and then turns badly when the power is applied then its probably not your CG but the motor angle.

Sorry this is all I could think of.

Todd

[wjcjr]

Did some crunching tonight and this is what I have learned thanks to everyone's help/suggestions here and a few other sources. This may get lengthy.

First when I added the CF rods to stiffen wing I did two things to adversely affect the wing.

One, the wing is not symmetrical from side to side. Looking aft to forward the the wing left of the fuselage has diehydral and the wing to the right of the fuselage is quite flat.

Two, again looking aft to forward the wing right of the fuselage is 3/16th's of an ounce heavier than the opposing side. The 3/16ths of and ounce is measured at about 3 inches in from the wing tip.

To eliminate this whole wing mess I bought a new one.

Secondly I took Jim's suggested reading and enlightened myself about Center. Of. Lift. and it's correlation to Center. Of. Gravity.. After this read which was quite interesting I did the math and this is what I came up with.

- C.O.L. is 1.78125" from leading edge of wing.

- My ideal C.O.G. would be between 1.78125" and 1.50"from the wing's leading edge.

- My actual C.O.G. is 2.56" from leading edge. This plane is so aft heavy it is alarming.

Armed with the knowledge above I will be making some changes to meet C.O.G. and try this all over again.

Wayne

[oldcaver]

Wayne: Our 450 ,on an EFlite stick mount(facing the bird) is shimmed1/8 top right,1/16 lower right, stock 2 deg. down.I think some of you r trouble could be too much throttle input early. Lots of motor torque and low ground speed torque rolls the cub quick. Try this before you go as nuts as we did when we were testing the larger engines:Roll out at about 1/3 to 1/2 throttle,get airborn and let it climb out without too much el input, and after she starts to scoot, then increase throttle.We're using either a 2100mA or an 1800mA LiPo and have had no probs with a 10x6 prop. More prop=more bite,and when you're testing a mod,it can get twitchy!We try to keep as many of the variables the same during x-tests,see what improves flight ,then proceed to the next idea that will screw it into the ground!LOL

[davemac2]

wjcjr said:

- My actual C.O.G. is 2.56" from leading edge. This plane is so aft heavy it is alarming.

You measured with the battery installed, right?

You definitely want your wing sides symetrical or it will try to roll away from the flat side.

dave mc

[wjcjr]

Funny you ask about the battery. After I did my COL markings and marked the ideal COG measurements I started hanging the plane by two points and then thought of the battery.

So yeah I did forget about it for a few moments. ;D It sounds you have expereince in this area as well...

Wayne

[wjcjr]

To return the universe to harmony (regain neutral COG) it took 1.50 onuces in the nose. Will be up thiis weekend!

wayne

[wjcjr]

YEAH that's more like it! First day of real flying after I gutted the plane.

The NEW Super Cub IS SUPER.

The new TX/RX/servos/ESC combo work GREAT! The degree of control I now have is awesome and very smooth.

That Park 450 with an 11X7 is a great step up from stock. I did not have time to use other props today but will probably Sunday. I have a 10X6, 11X7, 11X10 and a 12X6 here for me to experiment with. I put on the Du-Bro 2 3/4" tires so the 12 should clear no problem.

I am still using the 9.6V 1500 Elite NIMH battery packs. I timed 2 flights today, first at 16 minutes and second at 19 minutes. Neither flight did I hit the low voltage cut-off. To become fully recharged the first battery needed 743Mah and the second needed 962Mah. Concluding with those numbers I think I'll be able to pull off some where in the 25 minute area. I will need to time a full run, today was too windy for that. Also today I was doing quite a bit of cruising, the 450 effortlessly pulls this machine around.

So with that little bit of flying I must say I am adequately impressed with the set-up to say it was worth it.

Thanks for your help and suggestions.

I have a couple pictures to show thrust angles; when I am not as bushed I'll go figure out how to post an image and do it.

Wayne

[swampfox201]

Congratulations Wayne!!! Glad it's flying better now

[jt01]

Great job Wayne ! I'm sure all this information will help a lot of others down the road.

Jim

[mrmugen]

I pulled a newbie today. I sent the rebuilt cub up without checking the CG in 15mph winds. Was that a mistake! It was way aft heavy and made it real interesting to handle. It came back in one piece but was scary.

[wjcjr]

This sounds SO familiar ;D. Although mine really was not flyable. Remember the wing issue atop the CG.

How much did you need to add to the plane to level it out. Being a novice you are not do you fly a hair aft heavy for the snappy response?

Will be watching for your response.

Wayne

[swampfox201]

I'm thinking about adding a touch more more aft weight because mine won't flare right.