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Old Jan 28, 2004, 01:51 PM
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cadconversions's Avatar
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Yippee!
I'm feeling Chippy...and I can't hide it any longer!

Ok, here's the deal.

I love, and let me say that again, LOVE the super Chipmunk flown by Art Scholl's. It was my first control line plane that I was ever able to fly as a kid and I've never seen a better looking plane. I even have a Carl Goldberg model of this plane, but I don't fly glow that much. I wish someone had a chipmunk for parkflyers.

Wait a minute, I've always wanted to design a plane, have extensive AutoCAD experience, 3-views from Bob's Documentation...why don't I, oops we, design one....

Okay, here's the deal.

I'm starting to work on plans for a parkflyer chipmunk. I've already got a good start on getting the view digitized into my CAD package to begin work. However, I've never done this before so I will be asking a lot of questions.

I know that everything should be kept under the table until the design is finished, but I don't plan on doing this to make money but rather to have fun with something I enjoy. It's not often a man can mix his work and pleasure together at the same time.

Will the plans be available? Probably. Will the plane be kitted? Possibly. Will we all have fun? Absolutely.

So get yur thoughts together and be ready to build!

Kevin Carver
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Old Jan 28, 2004, 02:01 PM
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Ok, the model is a 1/10 sport scale model made famous by Art Scholl in the 80's. He was killed while filming for Top Gun in a Pitts Bi-plane.

Many of you have seen pictures and models of this plan but never in a parkflyer. We hope to change that.

The plane has a 36.5" wingspan is 29" long and will have a wing loading between 10 - 15 oz / sq ft.

Here's my first question. Art reduced his wingspan by 3' from a standard chipmunk. To do this, he also reduced his flaps by 3' to maintain better roll control. The flaps were later completly removed because he didn't have to use them. I've noticed on all of the more popular kits of this plane, that the flaps are always included. I don't feel (along with some of the ones I've already asked) that this plane really needs the flaps. However, they would be really easy to add, but there would be a weight penalty.

What's everyone's feelings on this?

Also, retracts are possible but for the time, I'm staying with fixed gear because of the weight.

The elevator and rudder will have hidden control systems (how cool is that) and the wings will have dual ailersons. I plan to have a firewal mount for the moto with optional knock outs for stick mounts. The plan should fly great in a GWS 350 motor and haul with the AXI 2212/26 that I plan to stick in it's nose when finished.

Battey access will be through the canopy and turtle deck.

Get ready, get ready, get ready.......

Kevin
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Old Jan 28, 2004, 02:07 PM
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Lubbock Texas
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I'm ready!!!!!!!!!!!!!!

I feel exactly the same about this plane as you.

Lee
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Old Jan 28, 2004, 02:10 PM
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Great to hear it Lee.

I didn't mention it above but the plans will have a detailed cockpit with floor pan and a carved balsa cowl is my plans as well. I would also like a pilot figure if anyone out there is creative enough for an "Art Scholl" bust or his dog Aileron.
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Old Jan 28, 2004, 02:11 PM
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I'll also need an artist to do a simple drawing of the "flying chipmunk" for the nose of the plane.
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Old Jan 28, 2004, 02:13 PM
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I am ready too!!!

I'm sure if people use a brushless system the oz from retracts will be neglible

I'll be keeping tabs on this!
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Old Jan 28, 2004, 02:16 PM
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Cam,

True but Art didn't use retracts that much on his planes but they are sooooo coool! If Doug from Mountain models was interested, his retracts would work great!
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Old Jan 28, 2004, 02:19 PM
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I don't recall it having retracts when I saw him as a kid. It had wheel pants as I remember it.
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Old Jan 28, 2004, 02:20 PM
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The FS2002 model I have of the Super Chipmunk(Not Art SChools, though) had retarcts. It also had wheel pants, and when the gear retracted the pants stuck out the bottom.
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Old Jan 28, 2004, 02:32 PM
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I recently graduated from college and have an airplane design class fresh in my head. I too want to design some aircraft and would be happy to be part of this project - if needed. What I would be interested in doing is sizing the aircraft and it's control surfaces - and airfoil selection. I havnt explored it much, but I think there is some potential to improve parkflyers performance with some better suited airfoils - low reynolds number airfoils.

It looks like you have already decided wing loading, dimensions and engine sizing - how did you go about that? Have you decided on control surface sizes? Simply scaling down a larger aircraft might not be the best solution.

I have some easy to use excel files created and could probably turn out some results in a few days - by Monday at the latest. Would you use the results?

What CAD packages do you use? I do CATIA V5.

On flaps, I would go with flaperons (if your radio has the mixing capability) since you already have two servos for the ailerons. I wouldnt add flaps.
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Old Jan 28, 2004, 02:43 PM
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CAM, that's what happened on Art's plane. The pants stuck out the bottom of the wing.

Abomination,


Great, I could use your help!

I've looked at the other kits on the market and for those in the balsa framed, solite covered, etc. market the wingspan was in the 36" +/- area. They all used the GWS geared 300 motors. So, I figured this plane would be the same. I also figured that the plane would be of similar weight to the other models available (15 - 20.5 oz) so that would put the wingloading at 15-20.5 oz divided by wingarea.....

I'm wanting this to be the best flier that it could possibly be. With that, I need a lot of help deciding upon airfoil, control surface sizes, etc..... What ever results you could come up with would be used in the design of this plane. However, you got to tell me what they are.

CAD Packages. If it ain't AutoDESK products, I ain't using it... Heee, heee. I'm drawing this plane in 2-d and pulling everything together the old fashion way. If your interested in doing a 3d model of the plane once it's ready for the laser cutters that would be a great way to make sure it all fits together.

I agree with you on the flaperons but I'm still open for suggestions. I want this to be "the plane that Rcgroups built"

Kevin
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Old Jan 28, 2004, 02:43 PM
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Great idea!

I like the idea. With the collective wisdom of all ezoners, this super Chipmunk is going to fly great!

Flap or not, with the slow speed of all parkflyers, I really don't think a flap is necessary. Cool if you have it, though.

Retract or not, unless you use Lipo and/or brushless motor, that retract carries a weight penalty. Probably start without, then decide if there is any margin for it.

Have you calculate the wing area yet? What is the target weight? Is balsa going to be the main material? (SturdyFoam or Depron is an option, but probably need to downsize the plan a bit.) Which airfoil are you going to use? Sorry, more questions than answers. If I were to design it, I would say the target wing area in 250-300 sq. in. (slow aerobatic, not fast), with target weight under 14. oz for 350 +NiMH power system. I prefer symmetic airfoil, but a semi one might work for more people. Just my $0.02.

Martin
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Old Jan 28, 2004, 02:49 PM
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Hey Martin, thanks for chiming in. The other planes in this market hit in the 15 - 20 oz range. I've calculated the wingspan yesterday but didn't write it down and I'm walking out the door right now.

Construction will be typical jig and tab balsa and ply construction with bolt-on wings. I would like to build it as lightly as possible. With the oval fuselage that the chippy has it will require stringers instead of flat sides with sheeting. I'm picturing Mike Molts' Hellcat type of fuse but only larger and different shape.

The chipmunk is a hovering type of plane, but should be able to fly the Imacc squences with grace, style, and a little gusto for those amazing verticals.

I'm planning for the first model to be a symetrical airfoil with a semi-airfoil to follow later if there is a desire for one.

Keep them coming.
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Old Jan 28, 2004, 02:53 PM
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Low Reynolds Number Airfoil

Hi, Abomination,

What low reynolds number airfoils do you have? Any polar diagrams? It would be interesting to see. I know there are quite a few research work for gliders, (SD series and such), but am not aware of any thing for Parkflyer (power, aerobatic). We could borrow an airfoil from those gliders', but IMHO, the design considerations are not the same.

Martin
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Old Jan 28, 2004, 02:55 PM
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Tucson, AZ
Joined May 2002
911 Posts
2 thumbs and 2 toes up!

Very cool. I think probably one of the most recognized planes
of all time.

I had the World Models Chippie. Real similar to the CG kit.

Flys sweet, lands true and a bit hot, but with flaps it was
a floater.

I know it would make a really great parkflyer.

Are you going for funscale? If so it would be really easy to tweak it into shape without the flaps and added weight. I say nay to retracts at first to avoid potential headaches. I don't have much more to add but will be watching this one with interest.
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