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Building Tips and technical articles. => 1/2 A building. => Topic started by: Robert Zambelli on April 26, 2020, 05:22:36 PM

Title: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Robert Zambelli on April 26, 2020, 05:22:36 PM
Here are some details.

Original In-Line design.
Power: OS .060.
Weight: 7 3/4 ounces.
Wingspan: 29 1/2 inches.
Overall length: 17 3/4 inches.
Chord: 6 inches (constant)
Trike gear because small planes like to flip over in grass!
Prop: TBD.

Hopefully I'll fly it in a day or two.

Bob Z.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Clint Taylor on April 26, 2020, 07:46:11 PM
That's a very neat design!
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: ray copeland on April 26, 2020, 09:29:33 PM
Awesome Bob! Nice weight for 1/2a. What tank you gonna try? The little apc props work well, may need to make a bushing and sometimes the cox 5x3 rubber ducky will give good results.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Larry Renger on April 26, 2020, 09:43:17 PM
With the short tail length and small tail feathers, start with pretty narrow line spacing at the handle and work your way out. Otherwise it is a beauty! Keep us posted on how it flies.

I have no experience or information with that engine, so am very interested in what performance you get.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Robert Zambelli on April 27, 2020, 07:59:32 AM
Thanks to all for the compliments and good advice.  #^  #^
Ray: At this point, I have a Top-Flite 7-6 wood prop, which I will cut down to 6 1/2.
It's a bit nose heavy so I'll stick with wood for now.
I did fabricate a bushing from 1/2 inch hex-stock aluminum since the shaft thread (8-32) is a bit short.
Larry: I have set up the controls to be quite slow but I will take your advice and keep the handle spacing narrow.

Bob Z.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Robert Zambelli on April 27, 2020, 09:40:52 AM
This is how I mount all my engines now.
Shown is the OS Max 061 and I'm also doing an LA 46.
Simple, light and reliable.

Bob Z.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Mark wood on April 27, 2020, 11:07:04 AM
Way cool. What did you finish it with?
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Larry Renger on April 27, 2020, 05:16:15 PM
Wow, a 7-6? I suspect a 6-4 would be more like it. The AP Wasp,and Norvel use much smaller props even than that. 5.5-2.5 and 6-2 or 5.7-3
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: pmackenzie on April 27, 2020, 06:09:34 PM
This is how I mount all my engines now.
Shown is the OS Max 061 and I'm also doing an LA 46.
Simple, light and reliable.

Bob Z.

How do you get to the nut (in the model) to tighten it up?
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Robert Zambelli on April 27, 2020, 09:10:53 PM
Quite simple - see the photo.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Larry Renger on April 28, 2020, 04:54:51 AM
Wow, that is a really small tank. How much run time do you get?
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Robert Zambelli on April 28, 2020, 07:50:31 AM
Hi, Larry.
The look is deceiving.
The tank actually extends around a half inch further back than is seen in the photo.
You see, the lead edge does not protrude into the fuselage.
As far as run time, I have only run the engine on the bench at this point.
If the present tank is insufficient, I can fabricate and fit a larger one.

Bob Z.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Robert Zambelli on May 18, 2020, 08:27:31 AM
Well, I finally got to fly it and I am really pleased.   #^   #^
First flight was a bit rich so I just let it run out.
Second flight PERFECT!   y1
It turns extremely tight with no noticeable loss in speed.
I was able to do most of the pattern but ran out of fuel before I could finish.
40 ft lines are too short. I will make up a set of 45 foot lines using 15 Lb spider wire instead of .008 cables.
6-4 Top-Flite wood prop, 25% nitro.

Another report to follow.

Bob Z.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: john e. holliday on May 18, 2020, 09:33:58 AM
Looks like a winner. H^^
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Larry Renger on June 05, 2020, 09:42:38 PM
Try lower nitro to get longer flight time and somewhat saner lap time, unless line tension is an issue. Keep us posted on how it is going!  H^^
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Larry Renger on June 19, 2020, 07:18:49 PM
Any news on later flights?  H^^
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: FLOYD CARTER on June 20, 2020, 06:06:40 PM
Conventional gear 1/2A models do flip over on grass.  So what?  They don't get hurt.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Robert Zambelli on June 21, 2020, 10:49:06 AM
Conventional gear 1/2A models do flip over on grass.  So what?  They don't get hurt.

Yeah, but the landings look a hell of a lot better!
Anyhow, I flew the plane on the 46 foot lines I mentioned earlier.
It really flies well but is still too sensitive - the reason I suspect, is a bit tail heavy and the controls a bit to sensitive.
I put a Master Airscrew prop on it and a longer elevator horn.
The weather in SC has been terrible - lots of wind throughout  the day.
I'm in Florida now but I'll be back home soon and will try out the mods as soon as possible.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: goozgog on June 23, 2020, 02:14:15 PM
Hey Bob,

That is a little gem of a stunter!

   My Focke-Wulf is very sensitive
even with a handle spacing of
2.25 inches.
  Your plane is even lighter than mine.

 
Joe Eiben, the electric scale flyer who usually has
a table at Brodak's, pointed out that the
drag of the L/G will affect the maneuverability
of a very light plane.

  The 9.0 oz Focke-Wulf turns VERY tight
outside corners that are hard to dampen.
I'm deluding myself that
"All little planes are twitchy!"  <=

Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Robert Zambelli on June 25, 2020, 02:44:04 PM
Way cool. What did you finish it with?

Hi, Mark - sorry for the late reply.
I guess I just overlooked it.
Anyhow, to answer your question.
The finish is quite simple - just light silkspan and Brodak dope.
I added some .5 ounce fiberglass reinforcement to the nose section.
Bob Z.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: L0U CRANE on July 09, 2020, 02:00:39 PM
IMHO, the reason so many "little" ukies feel twitchy and over-sensitive is that they too often have "1/2A" size bellcranks and horns.  I don't really understand why the "1/2A" stuff was done, except to "look like" it was more suitable for a smaller model.

For originals - of course - you can design-in space for "large ukie" (say 3") bellcranks, and use matching horn sizes. Those are the proportions, movements and feel we learned with our usual first successful model.

For external controls, like many profile and sheet wing 1/2As, you are free to relocate the bellcrank  a bit further from the fuse to prevent hitting it at full throw, or aft a bit if you don't like to see a bellcrank arm from above the model

Cramping the lines close together at the handle can do the same thing, but starts with a very narrow range of adjustability. Say the model flies with a noticeable non-level attitude, for example. Close spaced lines at the handle might not allow you to change wrist/finger grip or angle far enough to get it to fly level.

Sure, "full-size" hardware weighs more, but just how much more? Compare the added fraction of an ounce with repairing  or trashing a model for being too twitchy.

Try it, you might like it...
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Robert Zambelli on July 10, 2020, 02:51:59 PM
Thanks for all the good advice, Guys.
The plane is well dialed in now.
I lengthened the elevator horn, lengthened the lines, put in some engine offset, removed some tip weight and added a bit of nose weight - an APC 6-4 prop.

It really flys well now and I think I can go a bit longer on the lines - they're 46 feet now.

Bob Z.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Dane Martin on July 10, 2020, 03:15:49 PM
Outstanding work, as usual.

Al F. posted a reply on the line length post. Similarly equipped plane on 48' lines.  So I would guess you'd be good to go longer
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Robert Zambelli on January 21, 2021, 02:22:12 PM
Hi, All.

Since I've been away from planes for a while, I hadn't done much with the little stunter.
It flew well with the OS .061 but someone gave me a Norvel .061 so I'll try that.

IF, we ever get some decent weather!

Bob Z.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: GallopingGhostler on January 22, 2021, 12:42:29 PM
Concur with comments, that is a really sharp looking half-A stunter you have there, Robert, and with the rarer OS (Pet?) .061 nonetheless.

(OT) I purchased an OS Pet .06 from the now defunct Hobby Shack, Fountain Valley, CA in 1973. It was for my 36" GB Jr. Falcon R/C. To my surprise, they substituted without cost an OS Max .10R/C (1965 version) with butterfly valve exhaust restrictor coupled to the R/C carb. I powered the Falcon with a Cox .049 Golden Bee instead, but put the Max .10R/C in a 39" Top Flite Schoolmaster all sheet. Flew it on Ace R/C Pulse Commander rudder only with KRD sequential quick blip throttle servo. Wow, what an engine, full throttle it climbed out at 45 degree angle, half throttle like a .049, and whisper quiet at idle for low passes. Yet, at full throttle, its noise was only that of an unmuffled Cox reed valve .049. It is such a great engine that I have 3 of them.

Sorry for departing off topic. I imagine that OS would also make a decent C/L engine as well, being as strong of a cross scavenged engine as it was. Need to get off my duff, but got an original 36" Sterling Profile P-38 and 2 Enya .09-III with venturi intakes reserved, and get it built.
Title: Re: My First Try at a 1/2 A Stunt/Sport Plane
Post by: Juan Carlos Pesce on June 02, 2022, 12:11:32 PM
Dear Mr Zambelli,
I have been building my model airplanes for many years, currently I am 78, and I am very interested in your “Tweety Bird” model. I will be grateful if you send me the plan of it, or a 3-view diagram with the dimensions and the profile of the wing ribs. My email is: jcp541@gmail.com From already thank you very much.
Greetings from Buenos Aires (Argentina)
Juan Carlos Pesce