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Old Jul 05, 2001, 10:14 AM
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Paul's Avatar
United States, CT, Enfield
Joined Nov 2000
343 Posts
HL Super Cub wing folded in flight!

Has anyone had any experience with the Hobby lobby (Aerocraft) wing folding in flight? My super cub had about 25-30 flights on it and the other day I put it in a very shallow dive to try to loop it for the first time and as I was leveling off to start the loop the right wing broke off. This really upset me because I loved this otherwise great flying plane.

The entire nose of the plane was torn up from the impact, and I didn't even find the broken off wing because I was too worried about watching the spot where the fuselage crashed in the field so I could find it. If I had found the departed wing I would probably repair the damage, but without it I'm not sure if it's worth it.

At first I thought this was my own fault, but after noticing in the APC prop thread that DaveW had a similar experience with his HL Super Cub I thought I would post to find out more. I don't think a loop is an unreasonable thing to expect this plane to do.

Aerocraft: If you are reading this you might want to take a look the dihedral brace on this plane. It's a great design and has a small but loyal following. A gentle maneuver such as this should not end with a totaled airplane.

Paul
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Old Jul 05, 2001, 01:40 PM
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Oscoda, Michigan / Mississippi State University
Joined May 2000
153 Posts
I built a HL Supercub. I added ailerons to the wings actuated by a central HS-81 on a flex cable. My lite-ply wing joiner broke during construction so I made new wing joiners. I took 1/8" balsa, cut it to shape, and laminated it with .07 carbon fiber and CA on each side. I did it to the front and back of each joiner. I have put this plane through loops rolls and spins with an 8-cell pack without a problem. I also omitted the struts all together because they would just be extra drag and weight.

Now that I think of it I should check on that lite-ply dowel hold-down before I fly it again!

here's my SuperCub:



Notice the ailerons and the central servo in the sky-lite.



It flies! I am using 8 cell 600AE packs with 6v speed 400 on 2.33:1 gb. I switched to a 9-5 CAM electric prop and performance really improved.

-MarkVZ-
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Old Jul 05, 2001, 03:16 PM
D.G.B.
KOMET 44's Avatar
Southington, Connecticut, United States
Joined Jun 2000
2,951 Posts
Paul i had the wing on my Aqua Star do the same thing.the right half of the wing went straight up to form a perfect 90 degree angle.then it dropped from 150'. i just finished the rebuild of the fusaloge.the wing i only added shear webs.not much damage was done to the wing.thank god for ultra coat!! Come on now go fix it.stefanP
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Old Jul 05, 2001, 11:15 PM
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Folsom,Ca,USA
Joined Apr 2001
992 Posts
Hi gang,
I wasn't even doing a loop! It had looped a number of times, ( gently, throttle off on downside ). I was just trying to recover from a blown roll! ( mine has ailierons just like Marks )

Paul

Don't trash it!! Its fixable!
Mine is almost all fixed after about 6hrs work. I stripped the covering and replaced the broken sticks aft of the cabin area.
I built a new nose off the plans and just glued it onto the main bulkhead the wings dowels go into. Worked great! Straight as new. I had the the broken wing half so repairing it wasn't too traumatic. Right half was intact, only had to make one new rib, using existing ones for pattern.
I added a 3/32 hard ply brace that goes all the way out to the second ribs so it won't break again!

The ribs are all the same so you should be able to duplicate the existing wing in reverse and join it to the other one.
( With a sturdy center brace ! )
A lot less work than building a new one.

I assume your cowl is shattered. Mine was in five (5) pieces. I taped them back together with masking tape to " almost invisible seam" stage ( not hard) and then dusted all the seams, one at a time, with common baking soda. Then dribbled thin CA ( gotta be thin ) CA on the breaks. Welds everything together just as strong as new!
A little sanding and filling with plastic model putty and no one will ever know!

Soda fills small gaps and acts as an accelerator. Recommended by Satelite City ( CA mfg ) for this use.
USE GOOD VENTILATION, nasty CA fumes for sure as it kicks off instantly when it hits the soda.

It can fly again, better than ever!

Dave
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Old Jul 06, 2001, 12:26 AM
Senior Moments...I forgot
JohnC's Avatar
New Hyde Park, NY
Joined Mar 2001
1,007 Posts
I have buit several of the HL Super Cub and I never tried to loop them or shed the wing. If you do want to loop the cub then redesign the dihedral brace and or possibly make funtional the wing strut.

I have plans to make another one and make the wing stonger. It is a very nice flyer.
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Old Jul 06, 2001, 12:32 AM
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Granby, CT, USA
Joined Jan 2001
948 Posts
Paul, that's a shame. That was a gorgeous airplane. I had an adventure a great deal like yours some long while ago, I had a Goldberg 1/2A Skylane, tee-dee powered with rudder/elevator. Fool wing broke in half during some successive loops. Same damage. My post-mortem told me that I had seriously overstressed the wing with all my elevator authority coming round to level at the end of the (of course) last loop. I put more force into the wing than it could tolerate. By any chance did your Cub make nice tight loops? The wing is pretty well loaded up with motors and batteries and such. This being one of Pat Tritle's airplanes, I can't see a reason for it not being stressed for e-power, though. Maybe a phone call to Pat would help solve the mystery. I'll take your experience under serious advisement, as I have the a companion model to the Super Cub waiting to get built, the Farman. I'll see you before I build the wing, and we can gab a bit.
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Old Jul 06, 2001, 06:53 AM
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Okemos, Michigan
Joined Feb 2001
277 Posts
I don't know if anyone has considered this, but I have been looking into gliders recently. And I talked to a fellow who had a sig riser. Anyways I was looking at his wing construction (I guess he's won a few comps) and he put a small strip of thin fiberglass at the "center" wing joint to re-enforce it. Seems to me the best way to prevent wing failures on wings that are really light and could be subjected to high force. (Like a glider). I asked him if he have troubles in the past and his response was not after doing that.

The other thing that alot of e-zoners have been doing is using carbon fiber rods in mostly balsa models. I like this idea alot since it gives a wing flexible, but highly durable structure. (Check out the SR Cutie kit. It's wing is really cool.)

BTW: The super cub is a beaut.. Rebuild it!

-- Sean
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Old Jul 06, 2001, 08:28 AM
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United States, CT, Enfield
Joined Nov 2000
343 Posts
There are some very good ideas and points made above, and after thinking about it I think I will build another Cub from the plans. This one will definately have a stronger main dihedral brace and a few other improvements. I will also try the litespan I bought for the first one, but didn't use.

Now I have to find out if a replacement cowl is available from Aerocraft because mine is really smashed up. I could make a plug and vacuum form one, but that's a lot of extra work.

Thanks for the ideas and encouragement.

BTW: Nice looking Cub Mark. Peter, I looked at the Farman at the WRAM show and it looked great. Let me know when yours is done, I would love to see it fly.

Paul

[This message has been edited by Paul (edited 07-06-2001).]
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Old Jul 06, 2001, 08:34 AM
Senior Moments...I forgot
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New Hyde Park, NY
Joined Mar 2001
1,007 Posts
talk to Bill or Greg at Aerocraft about the cowl. They are very nice guys and I am sure they will come to the rescue. In fact ask if you can get a sheet of ribs to make the wing rebuild easier.
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Old Jul 06, 2001, 08:51 AM
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Destin, FL USA
Joined Nov 2000
558 Posts
Hi:
I don't think this applies to the Super Cub, but it's worth thinking about. On planes that have the wing held on with rubber bands, a major cause of wing breakage is too few bands. In a loop or similar, the front of the wing lifts, which greatly increases the angle of attack. As it starts to life, the pressure on the bands gets greater, and the lift becomes more. Even a strong wing can be broken in this way.
Regards,
Bob Stewart
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Old Jul 06, 2001, 09:10 AM
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Oscoda, Michigan / Mississippi State University
Joined May 2000
153 Posts
Does anyone still sell the Farman? I saw Hobby Lobby doesn't advertise it anymore. If I recall correctly it is lighter than the SuperCub, and it looks easier to build.

I was considering a Farman for a replacement for the SuperCub if it ever bites the dust.

-MarkVZ-
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Old Jul 06, 2001, 09:25 AM
Don't cut the Yellow Wire
dr.E's Avatar
Ridgewood ,NJ
Joined Jan 2000
3,542 Posts
Go directly to the aerocraft site and order the Farman from them. These kits were initially designed by Pat Trittle and are well laid out.
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Old Jul 02, 2002, 09:01 PM
The One....
genovia's Avatar
San Jose, Ca.
Joined Jan 2002
5,813 Posts
Hello all,

Allow me to jump in and tell you all, that I too am building a Super Cub. Thanks to Paul for giving me the warning ahead of time, that raised a big concern about the wings and it's strength in flight.

How do you guys inforce it with, and what to use?
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Old Jul 03, 2002, 10:13 AM
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tekochip's Avatar
West Dundee, IL, USA
Joined Jul 2001
845 Posts
I got a Super Cub for Father's Day, and mine's on the bench now. I read all of the wing stories, so I laminated my braces with some aluminum stock that I shaped.

Mark, there's no way any of my planes will ever look that good. Great job!
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Old Jul 03, 2002, 09:23 PM
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Folsom,Ca,USA
Joined Apr 2001
992 Posts
Hi, DaveW again.

For what I did, see previous post of a Jul 01 on this thread.

I also made the struts functional by putting ply plates in the wings and an anchor plate in the fus. The struts go into the wings with Z bends and are mounted to the fus bottom with #2 sheet metal screws.

Also check the angle of the stab to the wind!!

Horrible amount of "up" built in.

I lowered mine ( in the rebuild) to 1 deg or so
( very little) and it flys better. Not great, but better.

Mine was changed to a J3 in the process and looks
cute, but still is not a real joy to fly.

However, throttled back to a little over half it does cruise by in a most Cub like fashion, and at "just the right" power setting, the noisy Mini Olympus gb makes a sound somewhat like a real 65 hp Continental. ( emphasis on somewhat )

With the 3/32 ply joiner going all the way out to the second ribs and the more functional struts, I have had no problems. Struts are made from HARD balsa, and wire ends locked in with right angle bends and CA.

When I recovered it in Cub Yellow Utracoat, the plane gained 3 oz!! I thought the covering seemed heavier than the white and it is!!

It was right on the target 21 oz before so is 3 oz over now. But with specified power package it has plenty of power!

DaveW
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