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Not another Super Cub!!!!

#1
I am reliably informed that a model Piper Super Cub is not the easiest thing to fly.
Apparently it has to have coordinated rudder and aileron to turn and is prone to enter a spiral (the term 'tip stall' is not in any of the full size aviation books!) if flown too slowly.
For a plane that is a favourite of the Alaska bush plane STOL competitions this is rather surprising.

To find out if this is true I am going to build one, scale and in foam from this 3 view.
3view.jpg
And just to prove it can turn safely the rudder will be fixed. :eek: It will be 'bank and yank'.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#2
Charging through life without a rudder! Now that's courage!

or something else . . .


looking forward to the build progress!
 

earthsciteach

Moderator
Moderator
#4
My HZ Super Cub does just fine without rudder. My wing is clip and flattened - no dihedral at all. It will turn just fine with aileron input and a bit of back pressure on the elevator. No rudder required.

I call "tip stall" "stalling."

Looking forward to your build, as always!
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#5
My HZ Super Cub does just fine without rudder. My wing is clip and flattened - no dihedral at all. It will turn just fine with aileron input and a bit of back pressure on the elevator. No rudder required.
Same here. I use the rudder mainly for take off and landing, with a little use here and there during flight. I try to force myself to use it more and more, but usually just bank & yank.
 

Ak Flyer

Fly the wings off
Mentor
#6
I use the rudder all the time on all my aircraft. It's a good thing to learn. The benefits of rudder go well past coordinated turns. If you are thinking of trying 3D, rudder control is mandatory. With helicopters it's even more important to have the rudder thumb well trained. When you are trying to fly low and slow, the rudder is your best friend. When doing crosswind landings you need to have rudder control.

Full size super cubs are awesome. They are famous here in Alaska for good reason. While it's true that they tip stall and get into the "super cub death spiral" you need to remember a few things. The reason people die "cub deaths" by spiraling into the ground is strictly pilot error. Every plane has a stall speed, every plane. The circumstances around cubs are this: People are flying slow and low looking for animals. They find something and start turning around to look at it. They go so slow, so low, and turn so tight, that the inside wing goes below the stall speed and the plane slides sideways into the ground. If they were at altitude it would be easy to gain some airspeed and start flying again. Since people in cubs are hunting or sightseeing, they are too low to recover. Hence, supercub death spiral.

Any plane can do the same thing. A B52 was put into a steep bank at too low airspeed and altitude and slid into the ground. It's on youtube somewhere. The difference is the application. If you stall a Cessna 180 in the lower 48, you're probably nice and high and doing it on purpose or on takeoff but at least you're at full power on takeoff. The cub is still a plane, it's just a plane with stupid low speed capability and high payload. It's also front and back 2 seat high wing plane so the visibility is unparalleled.

Another note on STOL. If you watch videos of full scale STOL you will see lots and lots of rudder movement. To perform really short take offs and landings, you have to counter the torque steer from the engine thrust. You also need to be able to make corrections in your flight path while keeping the wings level. When you're going in somewhere really tight you need to skim the ground leading up to it. You don't want to be low and slow and start dipping your wings. When you're in a tight spot taking off, you need to adjust your path without having your wheels off the ground. Can't do that without rudder.

So, granted the cub will bank and yank just fine up high and at speed, but to realize the real benefits of the super cub you need to learn rudder.
 
#7
I am building this as a reply to the advice that you cannot fly a Super Cub without rudder and it also included "do not to use a flat bottomed wing section or over power it" which is why it will be using a true scale (slightly under cambered) section wing section and running at 180W/lb as well! ;)

What I hope to show is that the result has entirely satisfactory flying habits but obviously 'egg on face' if it doesn't!

As 40" span is quite a modest size it be a one piece plane which saves a bit of weight.
The first 'under construction' piccie. The RH wing nearly ready for the top skin.
NoSparWing.JPG
It is all 2mm Depron, there is no spar. Just like the full size it will rely entirely on the wing struts.
The Depron wing skins will be rigid enough to carry all the bending loads between the fuselage, strut attachments and the short overhang to the wing tips - I hope! :eek:

But it will be light. :D
 

pgerts

Old age member
Mentor
#8
Flying with aileron is absolutely no problem if you make sure to have differential throws. There are different ways to do it but no problems at all.
 
#9
Slowly progressing.
Servo mounted in RH wing, LH wing catching up.
LandRwings.JPG
The little dark blobs are local reinforcements for the wing strut attachments.
Fuselage next.
 
#11
The RH wing complete.
RHcomplete.JPG
The leading edge is a strip of 3mm Depron sanded to shape. To provide a bit of ding resistance the very front of the leading edge has a strip of 0.8mm balsa.
The wing half weighs exactly 1oz including servo and leads.

The beginnings of the fuselage with the formers.
FuseFormers.JPG
I intend to build it as a half shell over the plan.
I am undecided whether to include the 'glass'. It would be significantly lighter (and stronger) if the 'windows' were solid.
 
#12
Decision made - no glass. :eek:
The fuselage progresses. Again all 2mm Depron and unnecessarily complicated.
Fuselage1.JPG
Not built as a half shell as I originally intended but in one piece with full formers.
fuselage2.JPG
I think I can get away with the elevator servo right at the back of the fuselage.
 
#15
A bit more of the fuselage.
The Depron motor mounting tube.
MotorTube.JPG
This is a technique I first used on the Cessna O-2 and gives a very light rigid motor mount that is supported by the outer skin. The tube has a diameter slightly larger than the motor bell.
1500kV2805.JPG
The Emax 2805 1500kV motor will be mounted on a small wooden bulkhead which will be glued inside the tube to accurately position the prop.
 
#16
The weather is superb so at the moment I am doing more flying than building. :D
The front fuselage planking complete.
MotorMntd.JPG
The motor bell runs very close to the motor mounting tube. :eek:

So far it looks like it will come out below 10oz all up with an 800mAh 2s.
 
#18
xuzme720
You don't!
The complete motor assembly is fixed to the bulkhead before it is glued in place inside the tube.
A case of completely and permanently built in! :eek:

The basic flying surfaces to give an idea of its size.
WingsTail.JPG
 
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#20
I am reliably informed that a model Piper Super Cub is not the easiest thing to fly.
Apparently it has to have coordinated rudder and aileron to turn and is prone to enter a spiral (the term 'tip stall' is not in any of the full size aviation books!) if flown too slowly.
You have been mis-informed. It's the standard cub that needs rudder to fly correctly though most overpower the damned thing so much that the thought of stall from induced drag is ridiculous. It's the long wing. More like a sailplane then an airplane when you roll that long wing of a cub the induced drag on the top wing pulls the nose of the cub way to the top side? This puts a ton of side slip into the picture. Flown scale, your model will quickly slow down, the top wing will stall first and over the top you'll go into an inverted spin.
The SuperCub, which has more power and clipped wings and flaps, is not so prone to this condition because the wing is shorter. Most models though are way overpowered and can easily overcome the side slip drag. Fact is, the RCCA combat rules had to be re-written to allow only aircraft with fixed forward guns that flew in the war to fly. Stinking L-craft Cubs were winning all the time thanks to all the lift of the big long wing making great turn radius's and easy launches. They only ever flew that 3 channel Rons/Elevator/Throttle. The aircraft originally only had to have a proven kill in war to fly in combat. There was a case of a pilot fireing a sidearm out of the window of his l-craft and shooting down a fighter that had come up next to him. Probably wanted to force the observer down, got a 45 slug in the face instead, so it was a legal aircraft in the initial rules.

Enjoy the Super Cub BUT if it's not too late, can I suggest maybe building a Taylorcraft instead? It's like the cub only so much more classy AND not always hanging around the field like the dingleberries on a shaggy dog.