Posts: 1346
Joined: 12/29/2001 From: Monroe,
NC, USA Status: offline
Mowing 12 acres gives you a lot of time to think ... too much probably.
When I take Quickies to the field, people don't like the looks, and the V-tail just freaks them out.
If I take something as innocent as an F3D/30 out, even though it only does 110-120 mph (with a sport .36), it looks fast.
One day I was thinking, and an idea hit me. What if you took a Cub, and did the Q-40 skinny down and streamline until it only sorta looks like the real thing treatment? So I started drawing and things came together. At first I had the wide point at the back of the wing, and even though I could get the cross section down to 12.5 sq in at the front of the wing, I couldn't get the right shape at the rear of the wing. Then I figured out how to shape the fuselage so that the 12.5" is met and not have such a big penalty.
Then I started thinking about the wing. With an 8.25" chord and a 56" wing span, we can come in real close to 400 sq inches with the rounded tips. Having a constant thickness of the wing is not required by the Q-40 rules, only that a non-concave progression is used unless the full scale aircraft has a concave progression. So, we can meet the 7/8" no go at 3" out from the root with a NACA 66-012 tapering to something like a NACA 66-006 at the tip. This way we don't pay a penalty in frontal area.
It would be very similar to a Quickie in planform, except for the tail, but the fuselage shape doesn't have a 1/4" radius restriction, so we can streamline the fuselage quite a bit. And the wing would not be a drag either.
I cranked up the drawing programs and whipped out several revisions until I came up with this.
With a .32 in it, it will be a slightly faster than normal Cub. With a Q-40 (or Q-500) engine, it becomes a monster. Note that the spinner in the drawing is a 1.5", so airflow at the hub will be pretty decent.
J-3's have been raced, but I haven't been able to locate anything about it on the web. But I'm not surprised about that.
Posts: 1346
Joined: 12/29/2001 From: Monroe,
NC, USA Status: offline
Mike's SWRA plane is what got me thinking about it. They had to deal with scale judging, though. So I started with their concept and tweaked it for Q-40.
Hopefully he will comment. I would be especially interested in knowing what kind of times they did on a 3 pole course.
Posts: 171
Joined: 4/30/2004 From: Centennial,
CO, USA Status: offline
They have held up great. I've been tempted to put a Q40 motor on one but that little guy on my shoulder says different! They've been great practice planes.
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Joined: 4/24/2002 From: Arvada,
CO, USA Status: offline
Don,
You maniac, I wanna party with you.
I double-dog-dare you to bring it to the next J-3 Picnic, Fly-In & Uncontest in your area. In fact, while you're at it, forget about the QM40 rules and tuck a Nelson F.I.R.E. with full tuned pipe under the belly. Noise wouldn't be a problem; most of the other folks who'd be there can't hear frequencies that high.
You'd have to practice, though. You'd need to work up an impression of Paul Hogan ("Crocodile Dundee" saying, "That's not a Cub ... THIS is a Cub!"
Posts: 1346
Joined: 12/29/2001 From: Monroe,
NC, USA Status: offline
Kurt,
I would probably listen to that little guy. I had one with a hot Tower .46 with and Ultrathrust muffler on it, and I ran an APC 9x10 prop ... speed was near or maybe even above Q-40, but the plane only lasted 4 flights due to a cartwheel landing. Some people claimed they saw the wing flexing, and I was not flying pylon tight turns. The wing was not even hurt in the cartwheel, but the front of the fuse was busted. My sport F3D/30 has a Magnum .36 in it and it has hundreds of flights, and probably 25 people have flown it. Some of the landings have not been so great, so the bottom is scarred, but I just hit it with CA and sometime CA and microballoons, and it just keeps going and going.
DHG,
I love to party ... I'm all about having a good time.
But we don't have to worry about doing the FIRE, we can just hang a Bolly pipe on the side so that it sounds like a 98 db pattern plane, but still has the kick. Imagine the surprise when it uses a 5 foot takeoff roll and then comes by for a low pass at 180+.
Ed,
Come on ... do it I'm refining my pink foam plug technique, and I'm ordering some 3/16 basswood sheets to use for the backing plates / fin / rudder. The hardest part of the Hughes H-1 project was shaping the 1/8" birch, and I wasn't real satisfied with the shape of the fin. The basswood should work much better. I'm also thinking about using balsa instead of foam, but I hate the balsa dust.
Posts: 255
Joined: 6/28/2002 From: Arlington Heights,
IL, USA Status: offline
Ok, just because I have to...
Don, since you are in the designing mode another airplane that is legal for QM40 is the spirit of St. Louis. Because it doesn't have a cabin you might get the wing a little lower.
Posts: 1346
Joined: 12/29/2001 From: Monroe,
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Bill,
if you can figure out how to get around the 7.1. Conventional design.Aircraft used in RC Pylon events shall be of conventional design with forward wing, aft horizontal stabilizer, and a single engine mounted in front. No deltas or other tailless designs shall be allowed. An aircraft shall be considered tailless if the ratio of its wingspan to its overall length is greater than 2:1. The "overall length" of the aircraft, for purposes of this measurement, is the distance from the front of the propeller to the trailing edge of the rearmost movable tail surface. issue, the ram-air force on the exhaust port, and pusher propellors (or clockwise cranks), let me know.
... but just as I finished the above, I had an epiphany ... Nowhere in the rules does it say that the engine has to be in the same place as on the real plane ... How about a Pully Cat? The post 1974 version had a stab and elevator.
Posts: 1346
Joined: 12/29/2001 From: Monroe,
NC, USA Status: offline
Bill,
Here you go.
The biggest problem will be CG. The tank will have to be over or under the wing and will thoroughly test Ed's theory about fuel line length. All of the radio gear will have to be behind the CG.
Glenn Lee has 1.5" or 1.75" pie cutter wheels for B Proto Speed and one can be used with a CF gear on the front to save weight.
This plane would require a lot of trial and error. The long nose moment could be a deal killer.
Even though it has a horizontal stab, you would probably still have to use elevon mixing in some form.
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All Forums >> RC Airplanes >> Pylon Universe - RC Pylon Racing >> QM-40 Racing >> Piper J-3 Cub for Q-40 
Piper J-3 Cub for Q-40 - 
The Cub from heck! - 
saying, "That's not a Cub ... THIS is a Cub!" 
Piper J-3 Cub for Q-40 - 
