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Building Tips and technical articles. => 1/2 A building. => Topic started by: Larry Lindburg on December 10, 2011, 12:38:22 PM

Title: Another Dewey Cox
Post by: Larry Lindburg on December 10, 2011, 12:38:22 PM: I finally finished another Deweybird that I started over three years ago. Babe Bee power by Cox.
Title: Re: Another Dewey Cox
Post by: Tim Wescott on December 10, 2011, 01:16:34 PM: That looks very nice. I have some questions, though:

What size is the tank, and how long (do you know) of a flight does it make? (And is that a reall-o truely-o Babe Bee with the single-bypass cylinder, or is it hot-rodded?).

What did you use for paint?
Title: Re: Another Dewey Cox
Post by: Larry Lindburg on December 10, 2011, 05:38:30 PM: The tank is a BH-507 Brodak/Perfect which is 2/3 ounce. This setup will yield about 5 minutes on 25% Sig Champion fuel. The prop is the 5-3 Cox stiff prop, and this Babe Bee did about 15500 rpm on Sig 15% during testing.

I am not a hop-up artist. I do try to prevent air leaks and other problems during assembly. For instance I tried several reeds for a proper seal while assembling the engine. On this one I settled on a stainless steel reed. I used a spare Tee Dee piston and cylinder but had to fix the ball joint slop. Then I break-in and test the engine for reliable performance. During the testing I swap Cox heads and Merlin heads to see if there is better performance from either.

Paint is Lustrekote of which I seem to have a lifetime supply.

Did anyone notice the "Nitrotane" decal? I used it in the late seventies. Has anyone else used it?
Title: Re: Another Dewey Cox
Post by: ray copeland on December 10, 2011, 06:59:53 PM: Larry, the plane and the set up looks awesome!! Nice job, those tee dee pistons and cylinders are getting a little scarce. The Merlin heads and plugs are great. I hope it flies well and often!!! I love the little Deweybirds.
Title: Re: Another Dewey Cox
Post by: john e. holliday on December 11, 2011, 08:30:32 AM: Vendors Corner, check out Coxinternational. H^^
Title: Re: Another Dewey Cox
Post by: Andrew Tinsley on December 12, 2011, 02:33:46 PM: Doc,
Afraid not. The so called TDee pistons and liners are nothing more than twin slit exhaust cylinders, which have the divider milled out. The important extra honing at the bottom is not there.

Larry,
For someone who is not a hop up artist, you are not doing too badly!

Regards,

Andrew.
Title: Re: Another Dewey Cox
Post by: John Rist on December 12, 2011, 05:41:59 PM: Quote from: john e. holliday on December 11, 2011, 08:30:32 AM
Vendors Corner, check out Coxinternational. H^^

It's weird - A TD .049 jug and pistion cost less than a TD glow head.
Title: Re: Another Dewey Cox
Post by: Larry Renger on December 12, 2011, 09:19:09 PM: There are two differences between these "TD" setups and a simple hogging out of a RTF slit cylinder. First, they have added the "swirl" boost ports as used on the Venom, Killer Bee and last of the TDs. Second, they have shortened the skirt and lightened the piston so it has the correct sub-piston induction.

I plan to order a couple and test them myself. Also note they have the Killer Bee/Venom crankshaft available. Do it yourself Venoms!

See the posting on the Hollow Log Drag Race to see what a Venom can do!
Title: Re: Another Dewey Cox
Post by: Joe Rice on December 18, 2011, 08:59:12 AM: Another very nice Dewey, Larry. I love the trick look of the engine. Dewyou LL~ LL~ LL~have any any other 1/2 A projects on the boards?

Joe
Title: Re: Another Dewey Cox
Post by: Larry Lindburg on December 18, 2011, 08:59:17 PM: I dew have another Dewey in the works. It too was started three years ago. In the meantime I added heat shrink tubing to the filter on Dewey #3.