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Author Topic: Hal's Half-A Twin?  (Read 1493 times)

Offline Ward Van Duzer

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Hal's Half-A Twin?
« on: April 03, 2008, 11:17:27 AM »
I've been preparing a bunch of Cox parts for the Bay and realized that I have two pretty good Baby Bee's. Hmmmmmmmmmmm! And I've always had a "thing" for the DeBolt Half-A Twin. If you recall, this was published in Air Trails December 1951. Problem being it was designed around two Atwood Wasp's, presumably much smaller and less powerful than the Cox Bee's. The published plan has a wing span of Approx. 26 inches. I'm going to assume that would be too small for a twin with two Bee's.

Not being much of a 1/2 A maven myself, would anyone out there care to take a whack at what size Hal's twin should be scaled up to for two Baby Bee's? I don't suppose the scaled up version would be OTS legal, but that's not real important anyway...

Crazy Ward-O   n~
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Online James Lee

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Re: Hal's Half-A Twin?
« Reply #1 on: April 03, 2008, 01:50:51 PM »
Ward
Several years ago Todd and I did a pair of those...   We used Cox plastic back motors with ?Goldberg firewall mounts.   The problem was they shook and moved so much they were impossible to set and ran really weird...   Mine came to a violent end in level flight when they started to 'talk' to each other and it did a snap roll, flat spin and smash...!! ~^  ~^   ~^
Todd's still is in one piece...   We have thought about retrofitting it with solid mounts to get rid of the vibes...    Or a pair of Wasps with firewall mounts...   
and to answer your question with the Baby Bees I would think that 200 - 250 sq in would be a good starting point....   It will be definately be an eyecatcher!!
thanks
Jim   
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Offline Ward Van Duzer

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Re: Hal's Half-A Twin?
« Reply #2 on: April 03, 2008, 02:18:59 PM »
Jim,

Were you using the Goldberg PROFILE mounts. Yup, I was thinking of profiling it, but that sounds like a  b a d  idea now!

Thks...

W.
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I hate spelling errors, you mess up 2 letters and you are urined!

Don't hesitate to ask dumb questions.
They are easier to handle than dumb mistakes!  Ward-O AMA 6022

Offline Bob Furr

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Re: Hal's Half-A Twin?
« Reply #3 on: April 03, 2008, 02:40:13 PM »
I built a 15 size ringmaster with two golden bees about 20 years ago.  I still have it and it flys as well or better than the one I built with a Fox 15 (the old cross flow engine).   Motor mounts were in the wing like a 1/2a combat model with the inboard engine pointing straight ahead and the outboard engine offset about 5 degrees.  Nose where the engine would normally be was built up with some scrap 1/4" balsa to look like a 50's Piper twin.   It would fly (but not stunt) with either engine out.   Never had the problem with vibration but did have one engine that would quit inverted.... so I learned to finish my loops and not streach out my lazy eights.
Bob Furr
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Online James Lee

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Re: Hal's Half-A Twin?
« Reply #4 on: April 03, 2008, 03:01:02 PM »
Ward
those mounts were for the firewall and spaced the plastic back out about 5/16".   I will try to post a pic later
thanks
Jim
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Offline Robert McHam

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Re: Hal's Half-A Twin?
« Reply #5 on: April 03, 2008, 04:45:10 PM »
That Goldberg mount looked something like these and came packaged with a piece of fuel line and a balloon to use as an external tank. It  was designed for the "postage stamp" type of plastic backplate that was pretty much useless except in the RTF plastic plane it came in. Later Cox made the much   more useful plastic backplate that allowed firewall mounting like the modern day Sure Starts do.

Robert
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Online James Lee

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Re: Hal's Half-A Twin?
« Reply #6 on: April 04, 2008, 07:48:26 AM »
Robert
Those are the ones!!  With both motors running they would sometimes hit a resonance and crawl around like a pair of nasty tempered snakes....  That is essentially what caused the demise of the plane   ~^   They had plenty of power!!  I think we had 42' x .012 lines on it...  haven't dug into the flight logs
Jim
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Offline Robert McHam

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Re: Hal's Half-A Twin?
« Reply #7 on: July 11, 2008, 06:31:59 PM »
Quote by Ward-O:
"would anyone out there care to take a whack at what size Hal's twin should be scaled up to for two Baby Bee's?"

Ward, I would be happy to enlarge it for you. All I need is a decent scan of the plan (the article also would be nice).

I have a program that can enlarge and reduce jpg and even pdf files.
I might even take a crack at building one myself as I have a pair of Bees.

I really thought there would be more interest in this one!
Cool looking plane.

Robert
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Offline Larry Renger

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Re: Hal's Half-A Twin?
« Reply #8 on: July 11, 2008, 11:24:24 PM »
Howq about 360 sq.in. with a pair of .061 AP Wasps.  Since it was designed to fly with the Wasp, this seems appropriate...  n~
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 BTW, Dracula Sucks!  A closed mouth gathers no feet!

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