Kit Chipmunks

Stuka Stunt Main Forum · 11 of 11 known posts recovered

RocketCityJim · Aug 23, 2001 11:53 AM

Over on the Flightlines forum, there was quite a lengthly discussion regarding whether or not you could use the Super Chipmunk wing and build a MAN Van Loo plans fuselage and rest of the plane and have it be considered classic legal. Even Tom Dixon once said that it could be done that way. Well, I have copies of both sets of plans and have done some fine measurments. Besides the MAN Van Loo Chipmunks wing being 1&1/2 inches longer than the Super Chipmunks. The Super Chipmunk's root airfoil thickness measures at 2&1/16 inch. The root airfoil of the 67 Van Loo Chipmunk measures only 1& 15/16 inch thickness. Wheather or not the actual (original) foam wing Chipmunks flown by Van Loo and Stott were actually the same thickness as the wings shown on the MAN plans is anyone's guess. Probably only Mr.'s Van Loo and Stott would know, but in any case the wingtips on all versions are slightly different. Other differences between the two plans include stab/elevator length/area and moment arms. I would say to make sure that a Super Chipmunk wing was classic legal would take a bit of reworking. 1st, make the wing 1&1/2 inches longer by cutting a new spar and respacing the ribs. Then, if you insist on using kit ribs, cut them down to the thickness shown on the MAN plans.
Use the MAN Stab/Elevator, moments and rudder that is shown, along with the necssary nose modification to the cowling. Then you would have a classic legal plane that was somewhat fashoined from a Super Chipmunk kit. I think it would be more beneficial to get a copy of the foam wing that was cut for the original ones and use the MAN plans for the rest of the plane except the canopy. You could mould you own from a picture in a 1969 MAN article about the Team Trials. Then you would probably have it very close. The MAN plans show an airfoil section on the top of the Stab/elevator, but it's much easier to get the desired effect by just raising the leading edge of the stab about 1/2 to 1 degree. Gosh, they musta known about planes flying better with more lift coming from the stab back then too! Well, just shows that everyting old - sometimes comes out new again! Hmmm, sounds like good song lyrics! He, He...

Jim Pollock

Steve Scott · Aug 23, 2001 01:50 PM

#1 source

I'm not familiar with Van Loo's Chipmunk design but have an old Sig Super Chipmunk kit. Problem is, I don't want to build a SC, I'd rather build the std. Chip. I've wondered if I could modify my kit to resemble the Chip.

I also aquired a couple of foam cores many years ago that were for a Chipmunk. I assumed that was the SuperChip. I guess I'm going to have to do some measuring of these against the Sig plans for diffences. I suppose I'll also have to get a set of Van Loo's plans...

RocketCityJim · Aug 23, 2001 02:22 PM

#2 source

Steve,

Randy Smith has the Van Loo plans. That's where I got mine.

Jim

Steve Fitton · Aug 23, 2001 04:02 PM

#3 source

LAST EDITED ON Aug-23-01 AT 04:09 PM (CDT)

Why not build the Sig CL-3 chipmunk instead. Plans are obtainable for the early sig kit version and it came out I believe in December 1968-a year before the classic cutoff. I just finished scratch building one of these this summer, aided by using a sig superchipmunk wing kit. Same airfoil, same thicknesses, just slightly different flaps (they are not fullspan on the CL-3 version). It is a very nice looking airplane and more pleasing to the eye than the current superchipmunk. I also have the Randy Smith plans but no interest in building that version just yet.

Steve

Jim, I think Tom Dixon has the templates for the original VanLoo wing-which was a 57 inch span if I recall.

Steve Fitton

Steve Scott · Aug 23, 2001 07:15 PM

#4 source

LAST EDITED ON Aug-23-01 AT 07:18 PM (CDT)

>Steve
>
>Jim, I think Tom Dixon has
>the templates for the original
>VanLoo wing-which was a 57
>inch span if I recall.

Leonard also lists a Van Loo version - a 54" design:

Chipmunk. Jim Van Loo's 54 inch span full flapped semi-scale competition stunter that was the basis for the first SIG kit. No. 77B MAN plan. Two sheets, each 35 x 45. $16.00 for the set.

My Sig SC kit is the CL-19. Still has the original sticker price of $14.95!

RocketCityJim · Aug 24, 2001 07:11 AM

#7 source

Steve Yes,

The original Chipmunk had a 57" foam wing, however acording to a Mike Gretz post on the flightlines forum, the 55" foam wing versions were the best flyers and the winning combination for the Nats victory. As a side note, no one that tried the exact same thing later could get the Supertiger .40's to run the way Van Loo and Stott could. Again according to what was in Mike Gretz post.

Jim Pollock

Brett Buck · Aug 23, 2001 09:43 PM

#5 source

>Over on the Flightlines forum, there
>was quite a lengthly discussion
>regarding whether or not you
>could use the Super Chipmunk
>wing and build a MAN
>Van Loo plans fuselage and
>rest of the plane and
>have it be considered classic
>legal.

To avoid any possible confusion, "classic legal" is a matter of degree. The only penalty for errors/inaccuracies are the seldom-applied "fidelity points". There is no provision for DQing or not allowing the model to fly.

Brett

RocketCityJim · Aug 24, 2001 07:04 AM

#6 source

Brett,

Very true, I don't think any appearance judges in classic get out their rulers and calipers to finely judge fidelity.
Point well taken.

Regards,

Jim Pollock

Steve Fitton · Aug 24, 2001 09:26 AM

#8 source

Brett, your post regarding legality in classic prompts me to make a confession: I goofed in scratchbuilding my CL-3 Chipmunk. Since I was starting with a superchipmunk wing kit I built it over the superchipmunk wing plans. No problem untill I showed my completed airplane to my flying partner, and he displayed his identical chipmunk that he was in the process of covering. To my horror I discovered that I had full span flaps-and he didn't!! I kept quiet till I got home and yanked out my CL-3 plans. Yup, I should have studied them BEFORE I built the wing over the the CL-19 plans. I was half expecting to get DQ'd when I showed up at Charlotte with this plane this fall. Losing fidelity points I can deal with- Not like I'm going to beat the likes of John Simpson, Dixon,etc in classic anyhow.
I suppose I'll see how many people connect the plane with this post at the next contest. Chipmunks seem so infrequent these days that many people may not notice the flaps discrepancy.

Steve

Steve Fitton

Old Sourdough · Aug 25, 2001 01:32 AM

#9 source

Jim,

I was the person who quoted the MIke Gretz composed Chipmunk History/Evolution at Flightlines. I would be happy to send you (or any other interested party) the entire document if you'd like to see the chart that is part of it. The chart includes dimensions from measurements that Mike made from several of the various models.

Let me know. I tried to email you off the forum, but my email message was returned as undeliverable.

From what I read, the only Chipmunks that would be "Classic Legal" (Brett's comments below notwithstanding, even though noted and appreciated) according the letter as well as the spirit of the rules, would be copies of the earliest Van Loo/Stott versions, The MAN Plan version and the SIG CL-3 kit. The current SIG CL-19 kit would take considerable modification to the wing, empennage and fuselage (moments, not just cowlings, or other basically cosmetic items, etc.) to even come close to any of those versions.

That said, I, were I a Classic Stunt event director, would not DQ a potential contestant because of slight deviations, especially if reasonably serious attempts are made to duplicate the classic ship.

The Old Sourdough

The Old Sourdough
Ruksakinmakiak, Alaska, US of A

RocketCityJim · Aug 27, 2001 07:23 PM

#10 source

Hi, OS

How's things up there in good ole "Beer Can Cove"?
Long time since I was there. I last put my shadow on that turf about May 7 1967.

I would very much appreciate you E-Mailing me the full document that Mike Gretz wrote - A funny thing - Mike Gretz and my very best flying buddy in the late 60's and early 70's Mike Thompson knew each other from competing in the '70 Nats together. But that's another story. My correct E-Mail address is on the PAMPA web site. We have been having trouble with our E-Mail system there, I was trying to E-Mail Nils Norling in Oregon, whom I have E-Mailed several times in the past, and I kept getting my E-Mail returned. So I guess our systems is still a little fouled up. Please try again though. You never know when the gremlins will take a nap or break!

Thanks

Jim Pollock