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General control line discussion => Open Forum => Topic started by: Paul Taylor on December 10, 2009, 04:02:13 PM

Title: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: Paul Taylor on December 10, 2009, 04:02:13 PM
I see that Sig has the Chimpmunk canopy in stock. Anyone know if they are close in size? Chip vs Akrobat?

The one for the Akrobat is about 2 1/4 wide at the base, and 8 inches long.
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: wwwarbird on December 10, 2009, 05:19:11 PM
 I don't have exact dimensions here, but they are very close to the same size and proportion. Depending on what you are up to, keep in mind that the frame outline on the Akrobat canopy is molded for a rear bulkhead, it's not a true bubble type like the Chipmunk canopy is. Hope this helps.
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: David Russum on December 10, 2009, 11:36:23 PM
They are not interchangeable.  They are roughly the same size, but the front and back of the Akrobat canopy (where it mounts to the fuselage) is higher than the Chipmunk canopy.  The first picture shows the Chipmunk canopy on the left and the Akrobat canopy on the right.  The second picture shows the Akrobat canopy on top of the Chipmunk canopy.
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: Paul Taylor on December 11, 2009, 09:31:26 AM
They are not interchangeable.  They are roughly the same size, but the front and back of the Akrobat canopy (where it mounts to the fuselage) is higher than the Chipmunk canopy.  The first picture shows the Chipmunk canopy on the left and the Akrobat canopy on the right.  The second picture shows the Akrobat canopy on top of the Chipmunk canopy.

Thanks David,
Sig no longer sells the canopy for the Akrobat, but they do still have the Chipmunk. Your photos help a lot. It looks like I could cut a Chipmunk canopy to fit. I am still on the fence on if I can make a plug and make one from a pop bottle. Had a good phone converstaion with Bill Sawyer yesterday and he gave me some ideas.

Now I have to ponder this for a while...... D>K
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: Tom Rounds on December 11, 2009, 02:29:12 PM
If you had an Akrobat canopy could you make a plug from plaster paris(sp?) and then make all you wanted. correct?
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: Richard Grogan on December 12, 2009, 01:15:02 AM
If you had an Akrobat canopy could you make a plug from plaster paris(sp?) and then make all you wanted. correct?
Plaster of paris will work. Use  a paste wax or crisco shortening as a release agent in the master canopy.You can also lightly spray PAM in the master canopy to release the new plug.Lightly dust the mold with a(very) little baby powder to pull the actual new canopy. Should be able to pull 20-25 canopys with this plug, but it is fragile so use care!You can mix some fiberglass weave/theads in the plaster to help strengthen the plug(plaster is brittle) before it sets up in the original canopy.You could probably put a piece of piano wire in it length-wise, much like steel rebarb in concrete. Probably wont be as pretty as a polished mahogony plugged canopy, but will be functional.Hope this helps.

edit: I almost forgot.Let the new plug dry for about a week on a concrete floor. The concrete will draw the moisture out of the plug. The plaster is very pourous!This may sound like a lot of work/time, but its an easy way to clone from an existing canopy.
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: john e. holliday on December 12, 2009, 09:11:06 AM
When trying to compete in F2C we made our canopy molds out of casting plaster.  Sealed the surface with epoxy.  After the epoxy cures polish all the imperfections out.  Sometimes a second coat was applied.  If you don't seal the plaster it will take a lot of mold release to get the canopy to mold and release.
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: Don Curry AMA 267060 on December 12, 2009, 10:56:29 AM
While doing a scratch build of Leo Mehl's Arctic Fox, I needed a canopy for it. I went to a local hobby shop that sold a lot of arf eclectic airplanes. They had many canopy replacements for a lot of the war bird aircraft and I was able to find one I could trim and use. I was amazed at the number of different sizes and shapes that were available. It might be easier than building one but maybe you enjoy that part of modeling also. Just a thought.

Don
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: Tom Rounds on December 12, 2009, 12:24:12 PM
Rootbeard,
I have an Akrobat that I would loan you the canopy to make a plug  from. Just want to get it back and may an extra one to go with it!
Tom
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: Bill Sawyer on December 12, 2009, 03:05:08 PM
Tom
   If you will send it to me I will make a plug from it and give it back to you with an extra. I have done several this way.

Bill Sawyer
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: Gordon Tarbell on December 12, 2009, 04:23:35 PM
hey Bill I will send you my canopy for the Acrobat (still wrapped in tissue). Make the plug and send one to Rootbeard not me. Just send back the org. to me , everybody happy for Christmas. Let me know the address to send to
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: Gordon Tarbell on December 12, 2009, 04:30:35 PM
OOPs! didn't see Tom Rounds offer,  Any Who .   Lets get it done , if distance is an issue I am in Sacramento area,(Carmichael) to be exact. 
Title: Re: Anyone know if the Chipmunk and Akrobat canopies are about the same size?
Post by: Paul Taylor on December 12, 2009, 06:18:42 PM
Tom
   If you will send it to me I will make a plug from it and give it back to you with an extra. I have done several this way.

Bill Sawyer

Tom / Bill,
If you make one can you make an extra for me? Just tell me where to send the $$$.