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General control line discussion => Open Forum => Topic started by: Keith Spriggs on November 15, 2006, 11:09:53 PM

Title: Need info
Post by: Keith Spriggs on November 15, 2006, 11:09:53 PM: [img]About 35 years ago I built a model of the Chipmunk, I think it was a Sig kit. Anyway I got it done but I never flew it in fact I never even got an engine put in it. The plans are long gone so I have no idea where the CG should be. I intend to fly it next summer even if it disintegrates on take off. It has of course gathered lots of "hangar rash" in the last 35 year, but nothing to serious to fix.

Does anyone know where the CG should be? If not where would your best guess be as a starting point?
Title: Re: Need info
Post by: Mike Spiess on November 16, 2006, 07:35:26 AM: This may help.
Title: Re: Need info
Post by: Mike Spiess on November 16, 2006, 08:07:38 AM: By the way this is Mike Stott's Chipmunk hanging in my basenent. He sold it to my son some years ago. More on that story later.
Title: Re: Need info
Post by: Richard Grogan on November 16, 2006, 10:35:40 AM: Keith,
Yours is the second version Jim VanLoo's monk kitted by Sig in the late 60's, we had one too. The CG should be close, if not right on with what Mike's Super Chipmunk plans show. The main difference was the carved chin cowl on yours v/s the 2 pc full plastic cowl on the Super Chipmonk. Ours flew slowww with a Mc Coy .35 redhead (lightning bolt) with great line tension. I wish I still had it; it was stolen from my garage 23 years ago. It would easily glide a full lap after the engine quit!You should have a ball with it!

Mike,
I watched Mike Stott fly that bird at the 74' nats in Lake Charles making practice flights!
Amazing its still alive!!

Richard
Title: Re: Need info
Post by: Mike Spiess on November 16, 2006, 10:40:31 AM: Well it's in rough shape there was a fox 35 in it also this one has a sorta foam wing somthing Mike's dad was working at the time.
Title: Re: Need info
Post by: Richard Grogan on November 16, 2006, 10:51:16 AM: Quote from: Mike Spiess on November 16, 2006, 10:40:31 AM
Well it's in rough shape there was a fox 35 in it also this one has a sorta foam wing somthing Mike's dad was working at the time.
Does it have foam ribs, or is it a foam wing with wooden ribs? I think I remember reading something about the foam wing venture the Stotts were on, maybe something to do with Bob H and his dad too?C.R.S. is kicking in, soo..
Title: Re: Need info
Post by: Mike Spiess on November 16, 2006, 12:00:37 PM: Kinda halfway bettween lost foam and foam. The center was cut out and used to make half ribs and trailing and leading was left. Also one rib space at the tip and center section. A simple explanation about it.
Title: Re: Need info
Post by: Richard Grogan on November 16, 2006, 01:46:27 PM: Quote from: Mike Spiess on November 16, 2006, 12:00:37 PM
Kinda halfway bettween lost foam and foam. The center was cut out and used to make half ribs and trailing and leading was left. Also one rib space at the tip and center section. A simple explanation about it.
Sounds kinda' weird! Maybe"lost rib" construction!!??
Title: Re: Need info
Post by: Bill Little on November 16, 2006, 10:03:46 PM: Hi Keith,

Start with the CG about 1/4" or so behind the spar at the root. Even a *little* further back won't hurt to start out with.
Title: Re: Need info
Post by: Keith Spriggs on November 16, 2006, 10:29:09 PM: That answered my question perfectly. Thanks to all. Also thanks for the bit of modeling history.