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Building Tips and technical articles. => 1/2 A building. => Topic started by: Larry Renger on November 08, 2011, 11:03:46 PM
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We have a "Hollow Log" drag race coming up in December. Basically 10 laps from a standing start, Cox reed engines only. Minimum area 54 sq.in. and all components must have started from solid blocks and sheets. Front cross-section minimum - same as Babe Bee backplate.
I am building my own design, the Zippie. So far the basic airframe is 1 ounce. Still needs landing gear,bellcrank, leadouts, etc. It should come in at under 4 ounces.
I have a Cox Venom to put in it. VD~
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H^^ D>K Go lite on dope & it should be fast! :o <= n~ H^^
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Actually, since I intend to use 50% Nitro, Epoxy finish is in the cards. :X
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Why worry about longevity? It's just a one day thing, and by next year you'll probably have a different (better) idea of how to do it.
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When I take this much trouble to design and build a model, I want it hanging around looking good. It can function as a show model in our AMA Expo booth for years to come. n1
Next year we will have a one design race using Dale Kirn's Torquey biplane design. I don't know what the engine limitations will be yet, but I have a Cyclon, a Stehls and a VA in addition to some pretty darn good TDs. ;D
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It's coming along! I need to do the landing gear struts and cowl, but it could be flown after one coat of epoxy if I run out of time.
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It looks Sporty! Are you going to form up a cowl out of an aluminum can or build it from Balsa?
Mark
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I have already made a form to mold a fiberglas cowl. I will use epoxy and the balloon method. Probably 2 layers of 1ounce cloth, one straight, the other at 45 degrees. I also have Kevlar and carbon veil materials.
The form is blue foam with a 1/32 ply front ring that will be bonded to the cowl. At the back is a 1/8" ply match to the firewall to assure a good fit. I ironed SLC covering onto the foam and will coat that with PVA release.
Lay on the 'glass, and then push an inflated balloon down over the whole thing to apply pressure and form a smooth outer surface. The pressure will squeeze out any excess epoxy. I have done lots of 'glass vacuum bagging, but not this particular technique. Wish me luck! ~^
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I am sure you will do fine Larry. I cannot wait to see the results~!!!
Mark
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BTW the whole build and plans will be in a several part series in the Half A Flyer magazine, so sign up, Yall! n1
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I think this is the first time I've looked at the 1/2A section. Looks nice Larry, reminds me of a real plane but I can't think what. May be some sort of Lockheed?
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What were that Spitfire and Hughes H1 racer DOING in that hangar last year? VD~
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Larry--Next year no engine restrictions anything up to 1cc
Bob
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Bwhaaaaahaaahaaa! VD~ :X DV^^
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Here come the custom built engines. And they wonder what killed 1/2A Mouse One. VD~
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The upcoming race is for unlimited engines, and does not apply to Mouse at all. ;D
An upcoming article in the Half A Flyer will be how to build a competitive reed engine. In addition, the Venom, which was mass produced by Cox, was superior to home modified engines because we (Cox) could do things the home builder could not! Paul Gieabault could confirm that he held record with a Production Venom engine. We worked together to develop it, but was then produced in quantity. I am not aware that further fitting or modifications were used, and I think he still has and uses the stock engine. Perhaps he will respond here.
I intend to show how to build your very own version. Subscribe and stay tuned! mw~
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HI Guys,
Yes indeed, the Cox Venom was the fastest Cox engine. It had better cylinder porting, a lightened piston, a better balanced crank + the nylon reed retainer (although not faster) was more reliable. The ONLY modification I do is to replace the original piston with that from a TeeDee. And then ONLY IF the original piston has failed. The (still current) record holding engine was indeed stock including the glow plug. I dis-assembled it right at the Nats to prove it...
The major dissappointment with the Venom was it's fragile piston. Sadly, if they had just made it per Larry's direction, it never would have failed. My original Venom prototype (from Larry) is still going strong with all original parts. I keep it as a 'reference engine' & mostly just bench run it. It's always packed in my mouse kit as an emergency #4 back-up engine. (Any AMA NATS is considered an emergency...!)
I'm green with envy not being able to enter the 'hollow log' event!
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Larry, the plane as it is shown in the picture with the carbon veil applied is 1oz. sitting as is? I've been building some combat wings which I though were fairly light. I can't seem to bring them under 3 oz's. I'm using arrowshafts and fiberglass composite tubes for my fuse. My lightest with all the weight stripping I can do is 3 oz on the money. I guess I have to keep trying. I've been using a lot of white glue thinned down but I don't want to sacrifice strength either. Ken
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Well, I used a block of balsa for the fuselage that I had to scrape off the ceiling, and the wing wood was about that light too. I have been collecting good balsa for at least 40 years, and it just gets lighter with age. Also, this model is TINY! 54 sq.in. with a minimal cross-section fuselage hollowed out. y1
I just finished sending the first "episode" in the ongoing saga of construction to "Half A Flyer. Plans are included.
Paul Quote: I'm green with envy not being able to enter the 'hollow log' event!
So build one and we can easily find a proxy flyer for you! They do that in the multi-engine profile scale contest in Tucson and most of the Musciano events. :!
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I had to add tail weight, and the cowl and spinner and wheel pants are not done. But tomorrow is the race. HB~>
It has two coats of Klasskote epoxy on it, so after the race I can clean it with anything I need to and do the final finish. Plus, even the hi Nitro fuel shouldn't touch it.
Current weight is 4.3 ounces. When finally complete, I suspect I'll need even more tailweight, and it will push 5 ounces. I should have cut the nose 1/2" shorter. Oh, well..... Then again, after the race I have time to do it right!
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Larry,
Do you have any pics of the finished plane?
Thanks!
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No, because it isn't finished. HB~> I still need to mold the cowl, and then apply the deco. It did win, however. I made up a pseudo Venom with a small tank, as the normal one 'bout killed me! Laps under 2 seconds for about a minute had me staggering.
The next race is at the Toys for Tots in December, so it needs to be done then. We are going to longer lines and providing (much milder) fuel. 65% Nitro plus Propylene Oxide was a bit much with that itty bitty APC 4" prop. I'll wager that reedie was singing a 30K note.
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2 second laps? I'm dizzy just thinking about it. I'd like to build something like it, someday...(if there were ever any plans for it, hint,hint)
Thanks!
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Talk to Larry Rice, he has the plan and article for Half A Flyer. y1
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Since Blackhawk Models and 1/2 A Flyer are. Gone, if there is interest the plans can be posted here.
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Interested!
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Good idea!
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I've been interested in 1/2 A flying since I learned as a kid in the early 50's. I lived in Southern Cal. not too far from the Cox Factory and a whole gang of kids learned to fly on the PT-19!!
Now I can't fly anymore But I still love to build all types but especially 1/2A, on my bench now is a !/2 A Twin engine with OK Cub 049 Engines and a Hollow Log plane I am going to call "Fuzzy" trying to keep up with Larry & Dane!
Going back to the bench, RK Flyer
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Twin? Twin? Did I hear something about a twin?
I love twins!
Pics please.
TIA
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Jim......I am still working on it and I don't know how to post pictures .But the plans are on the Outer Zone. Its called the "Half A Twin" by Hal De Bolt 1951. Its a nice one!!
RK F lyer
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RK,
I know the one...Grumman angle-rudder, dual tail, cockpit "nose" ends behind the wing trailing edge, if I have the right plane. This is one I'd like to see completed.
Please do post once you figure out how. Posting here is pretty easy once you learn how to resize for the file-size limit.
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You can email the pics to me and I'll resize them. Or if they're on your phone, sometimes you can text them to yourself and save again. It'll save, resized in a different folder.
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I hav posted photos and plans on a separate thread. If needed there are detailed construction photos that are ready to post
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Hi Mr. Larry,
Please post the link to your thread. This is one plane I'd like to see.
Oh, BTW...I love my RSM 1/2A Renger handle!
I know, I know...we are threadjacking RKs post. Sorry RK!
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Search for Zippiee and you shall be rewarded!
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Hi Mr. Larry,
Please post the link to your thread. This is one plane I'd like to see.
Oh, BTW...I love my RSM 1/2A Renger handle!
I know, I know...we are threadjacking RKs post. Sorry RK!
Jim, the pdf download is right directly above the picture.
https://stunthanger.com/smf/12-a-building/zippiee-racer-information/
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Well, I used a block of balsa for the fuselage that I had to scrape off the ceiling, and the wing wood was about that light too. I have been collecting good balsa for at least 40 years, and it just gets lighter with age. Also, this model is TINY! 54 sq.in. with a minimal cross-section fuselage hollowed out. y1
I just finished sending the first "episode" in the ongoing saga of construction to "Half A Flyer. Plans are included.
Paul Quote: I'm green with envy not being able to enter the 'hollow log' event!
So build one and we can easily find a proxy flyer for you! They do that in the multi-engine profile scale
contest in Tucson and most of the Musciano events. :!
thought the rules said 56 aq in wing