I can't fly 55!!! (Need to slow down my Cub)

[clipper453]

I think I may have inadvertently made my already fast brushless Super Cub even faster by accident. I wanted to get rid of the wing struts, so I used two 40" long carbon strips to reinforce the wing. But instead of burning a recess in the wing for them, I took the shortcut method and CA glued them to the wing surfaces (one on top and one on the bottom).

After letting it cure for 24 hours, I took it out for a test flight tonight. It flew great, and I was able to do several high-G loops to test out the strength of the wing. But upon landing, I noticed that the Super Cub came in much faster than it ever did before. I even verified with my SkyTrace GPS system that the plane had a maximum ground speed of over 55 mph at one point in the flight!

I think two factors play into this, but I'm looking for other ideas as well. 1) Less drag from removing the wing struts. 2) By adding the carbon fiber strips to the top and bottom surfaces of the wing, I think I may have disrupted the air flow over those surfaces causing less drag on the wing (kind of a like a dimpled golf ball will travel further than if it were smooth). Basically, I think the strips break the boundary layer of the air moving past them.

So does anyone have any suggestions on how I can slow down my Super Cub upon landing? (I always come in at zero throttle, and I even reprogrammed my ESC to "brake" the prop at zero throttle instead of letting it spin freely.)

For those interested in seeing my SkyTrace GPS output, check out my post on RCGroups:

www.rcgroups.com/forums/showpost.php?p=10322471&postcount=73

Thanks,
Matt

[05prostock]

For one, if you have ailerons and a programmable transmitter you can make flaps.
I did this on my easy star and it works quite well. (even though it comes in slow in the first place...)

Or try to reduce the weight of your cub.
I know after a few months of flying with my first cub I put about 10oz of epoxy in it ;D
So a new body may be the key.

[SCC]

Aug 11, 2008 7:29:29 GMT 1 clipper453 said:

So does anyone have any suggestions on how I can slow down my Super Cub upon landing? (I always come in at zero throttle, and I even reprogrammed my ESC to "brake" the prop at zero throttle instead of letting it spin freely.)


Thanks,
Matt

Set your brake to off. A free wheeling prop will slow your plane down.

[mrmugen]

Also, brake will cause your prop to loosen. Do not use a brake. If you must then make sure it is a soft brake. It sounds like you don't have much dihedral left in your wing......maybe?

[clipper453]

05prostock... I might go with the flaps idea (as a last resort). Surely, I've added my share of epoxy to the plane in the last month or so, so maybe a new fuselage would be in order.

SCC and mrmugen... On my next outing, I'll try it with the brake set to off again. I'm using a CommonSenseRC 20-Amp ESC, and I believe the brake is a soft one. It does allow the prop to still turn with the throttle off, just at a much slower rate.

The wing still has plenty of dihedral. I don't think I affected it at all. I might also try adding a strip of packing tape to cover the carbon fiber strips, to help the aerodynamic transition over them.

Thanks for the help.

- Matt

[mrmugen]

You could be nose heavy too......most likely the issue.

[clipper453]

Aug 11, 2008 16:12:35 GMT 1 mrmugen said:

You could be nose heavy too......most likely the issue.

Could be. I'll just have to cut the nose off I guess.

Actually, I have been mounting the GPS receiver to the "windshield" of the plane. Maybe I'll try a flight with it moved back on top of the wing, or even take it off altogether.

- Matt

[ace1726]

More gradual approach? Maybe too steep??? Also, definitely power on. I usually cut throttle as the mains come in contact with the ground.