Author Topic: General 1/2A Design Question (Read 4385 times)

Steve Berry · « **on:** April 21, 2025, 07:38:10 PM »

This is sort of 1/2A (strong 0.061-0.074, or a BadAss 2310-1220 (or -1680) which would put it in the range of a good 0.10.

The design is a scaled down Gieseke Nobler, 250in², designed to be electric. I'm wondering if 1/32" or 1/16" basswood fuselage sides would be good with no doublers. Punk balsa can be added as needed for shaping purposes.

Thoughts?

Steve

Dave Hull · « **Reply #1 on:** April 23, 2025, 02:24:02 AM »

For a true 1/2A fuselage you can use 1/16" balsa sides. For something quite large in the 1cc range you might go up to 3/32". The basswood is likely to be 2.5 times the density of balsa, best case. To try to keep the weight under control you would need the basswood to be 1/32" or thinner. My estimate used 8 lb balsa and 20 lb basswood. Go measure some pieces if you get serious about this.

The problem that you get into applies not only to models, but to full-scale aircraft design--what mass props guys call "minimum gauge." To get to an equivalent weight in a more-dense material you end up so thin that you have problems with buckling, problems with manufacturing (assembling), even making the parts. That can be dealt with in some ways with chemical milling of aluminum sheets, but.... In the basswood vs. balsa tradeoff I think you are looking at a serious challenge to avoid a lot of weight growth. Instead, I use 1/64 ply doublers inside the nose area and balsa sides. One of the main purposes is to spread out the loads from the engine mounts. To be effective, you need better tearout strength than just the balsa--the spruce or maple engine mounts glue very nicely to the birch plywood. If you keep the weight of the glue down, it works fine and is quite durable. Let me look and see if I can find a picture of that.

Just my thoughts, good luck with your project!

Dave

Ken Culbertson · « **Reply #2 on:** December 18, 2025, 11:11:07 AM »

Quote from: Steve Berry on April 21, 2025, 07:38:10 PM

This is sort of 1/2A (strong 0.061-0.074, or a BadAss 2310-1220 (or -1680) which would put it in the range of a good 0.10.

The design is a scaled down Gieseke Nobler, 250in², designed to be electric. I'm wondering if 1/32" or 1/16" basswood fuselage sides would be good with no doublers. Punk balsa can be added as needed for shaping purposes.

Thoughts?

Steve

Steve, I am embarking on a similar project. I am curious about the span of your project. I am also considering the 2310-1220 on a 2s battery. With all of the other goodies it looks like 250grams or so on a 3s 2200mah battery. 2 may be enough at 2200. I want full pattern. That is about 8 oz for the power train. I think I can build the airframe under 15oz. That makes the target weight around 25oz with a whole bunch of slop. My "rule of thumb" is about 10in² per ounce minimum which is probably low. I checked the two flying PA ships I have and both were about that ratio. So, have you made any progress on yours and, most of all is 25oz a realistic weight goal?

Ken

Steve Berry · « **Reply #3 on:** December 18, 2025, 12:41:24 PM »

I haven't really made any progress on it beyond design phase. The span is just a touch under 35 3/4", 250" sq., with a ready to fly weight anywhere from 19oz to 25oz.

Upon review, using 1/16" balsa for the fuselage sides, 3/32" aircraft ply motor mount, 3/32" lite ply for the F2 & battery compartment components, 1/16" cross grain for the rest of the formers, perhaps 1/32" molded balsa shells, with the entire fuselage covered with .2oz carbon veil should work. Tail feathers built light, and of a course a built-up wing...I think it can be done.

I'm attaching a rough "in-progress" copy of where I'm at right now. I do have ribs drawn/lofted, they simply aren't on the print. It's a work in progress and I'm considering changing the front end from rear mount to perhaps front mount, but that will really depend on the motor used (some motors that small have the mount machined into the stationary part of the can, so it can only be rear mounted).

Steve

Ken Culbertson · « **Reply #4 on:** December 18, 2025, 03:49:23 PM »

Quote from: Steve Berry on December 18, 2025, 12:41:24 PM

I haven't really made any progress on it beyond design phase. The span is just a touch under 35 3/4", 250" sq., with a ready to fly weight anywhere from 19oz to 25oz.

Upon review, using 1/16" balsa for the fuselage sides, 3/32" aircraft ply motor mount, 3/32" lite ply for the F2 & battery compartment components, 1/16" cross grain for the rest of the formers, perhaps 1/32" molded balsa shells, with the entire fuselage covered with .2oz carbon veil should work. Tail feathers built light, and of a course a built-up wing...I think it can be done.

I'm attaching a rough "in-progress" copy of where I'm at right now. I do have ribs drawn/lofted, they simply aren't on the print. It's a work in progress and I'm considering changing the front end from rear mount to perhaps front mount, but that will really depend on the motor used (some motors that small have the mount machined into the stationary part of the can, so it can only be rear mounted).

Steve

You are still ahead of me! I am still in the pencil sketch mode. 32" about 310 squares and a target weight of 25oz. I am curious how you plan to get a full pattern out of an 880mah battery? I am running the 2320 now and it easily eats up 1500 on a 5s battery. Maybe probably I am missing something. This is going to be a fun project. Working out how to get the Canard pushrod and the battery in the nose will be fun. I am pretty sure I will use a front mount too. I have a couple of 2320's that I can slip in if it proves to be under powered. That airfoil on your Nobler plans is one I have used at least 10 times. I has a set of metal templates I made in the 60's. They lasted till the 2020 fire.

Keep me in the loop - Ken

Sorry about the crappy photo.

Larry Renger · « **Reply #5 on:** December 19, 2025, 09:03:54 AM »

I have published four competitive stunters in the 250 sq. in. range. (Baby Magician, Sky Sport, Skyfire 2, and Sky Streak) They all weighed around 10 ounces. 🤠

Dave Hull can attest to how they flew. 👍

Larry Renger · « **Reply #6 on:** December 19, 2025, 09:27:46 AM »

The Cox Me109, Chipmunk, and Hyper Viper stunters were all in the 165 sq.in. range and would only do the widest maneuvers. They all weighed in about 11 ounces. ☠️😱😥

You should get an idea about acceptable wing loadings from all that. 🤠

Dan McEntee · « **Reply #7 on:** December 19, 2025, 10:47:21 AM »

You might want to consider this:

https://outerzone.co.uk/plan_details.asp?ID=4699

I built one of these many years ago, and added a turtle deck and squared off rudder to resemble the Gieseke Nobler. Power was a TD .049 I think, it's been a while. The model was capable of the whole patter on one tank, and it was actually the first airplane that I did square inside and outside loos with!! I was using .101" music wire to fly it on. I don't remember the weight. The model still exists, and is hanging in my garage, and just might get a refinish. It was painted with AeroGloss, so that should give you an idea of what the covering and finish look like 30 some odd years from when it was last flown!!

Type at you later,
Dan McEntee

Dan McEntee · « **Reply #8 on:** December 19, 2025, 10:56:01 AM »

Quote from: Larry Renger on December 19, 2025, 09:03:54 AM

I have published four competitive stunters in the 250 sq. in. range. (Baby Magician, Sky Sport, Skyfire 2, and Sky Streak) They all weighed around 10 ounces. 🤠

Dave Hull can attest to how they flew. 👍

Hi Larry;

Were all four of these published in Flying Models? I just want to revisit the articles. I think the baby Magician was, but can't recall the other three?? If not all in FM, do you remember what hag they were in? If I get that much I can figure out the rest pretty easy. THANKS!!
Type at you later,
Dan McEntee

In fact, while I'm asking, do you have a bibliography of all your articles and published designs!! That would SO COOL to have pinned at the top of the 1/2A section!!

Larry Renger · « **Reply #9 on:** December 19, 2025, 12:18:59 PM »

Yes, all in FM. If necessary, I can provide copies of the articles. 🤠

I’ll get a bibliography together and post it. 😁

Dan McEntee · « **Reply #10 on:** December 19, 2025, 10:31:57 PM »

Quote from: Larry Renger on December 19, 2025, 12:18:59 PM

Yes, all in FM. If necessary, I can provide copies of the articles. 🤠

I’ll get a bibliography together and post it. 😁

Thanks Larry!! I have the magazines. I thought one or maybe two was in Model Builder. Seeing your complete body of work will be interesting!! I'll bet many don't know you published stuff from hand launched gliders to rocket powered gliders!!

You been around man!!

Thank you and type at you later,
Dan McEntee

Larry Renger · « **Reply #11 on:** December 20, 2025, 09:21:33 AM »

Well, here it is:

PS: that was enough to put me in the AMA Hall of Fame in 2010. 🤠

Paul Smith · « **Reply #12 on:** December 20, 2025, 10:24:05 AM »

The Flying Clown, as currently used for Brodak 15 Clown racing can be built light and used as a full pattern stunter with a TD .049.

And, of course, also entered in OT, Classic, N-30, profile, and F2b.

8 ounces ready to fly, less fuel.

Larry Renger · « **Reply #13 on:** December 20, 2025, 07:32:54 PM »

What did it end up weighing and what is the wing area?

Dan McEntee · « **Reply #14 on:** December 24, 2025, 10:07:47 PM »

Quote from: Larry Renger on December 20, 2025, 09:21:33 AM

Well, here it is:

PS: that was enough to put me in the AMA Hall of Fame in 2010. 🤠

WOW!! Quite a history!! I just finally had a chance to download it and read it. I know I have been reading your name in the mags since the 60's, but knew it would be impossible to just go looking for your work and find it all. A body of work well worth the AMA Hall of Fame!! I was very pleased to have met and talked with you a bit on a few trips to VSC and hope our paths cross again in the future.

Everyone out to check out this list and download it for future reference.

Thank you very much and MERRY CHRISTMAS!!
Dan McEntee

Tim Wescott · « **Reply #15 on:** December 25, 2025, 02:16:26 PM »

125 square inches, 7 ounces, 24" span. Does loops & wingovers.

A follow-on mod shortened the nose, took weight off the tail & got down to 6 ounces. Overall it flew better, but even then "square" maneuvers are too hairy to attempt unless you're very good.

Flies maybe 3 minutes on an ~~800mA-h~~ 500mA-h (oops), 3-cell pack; that's not enough for a full pattern.

I have similar-sized planes with plank wings that don't maneuver as well -- having an actual airfoil seems to make things much better.

Ken Culbertson · « **Reply #16 on:** December 25, 2025, 04:31:16 PM »

Quote from: Tim Wescott on December 25, 2025, 02:16:26 PM

125 square inches, 7 ounces, 24" span. Does loops & wingovers.

If "rules" are made for 1/2a electric (assuming there still is such a thing) eliminating the extra lap do you think a 3s 1100 would work? Is there any guide somewhere that defines what a 1/2a electric is? Do we use the Watts rating perhaps? I was planning to build for a 3s 2320 motor. Too big?

Ken

Ken

Tim Wescott · « **Reply #17 on:** December 25, 2025, 09:09:23 PM »

There is no guide. When I'm not being lazy I say ''1/2-A sized".

Note that I said 800mA-h -- I was recalling things wrong. It's 500mA-h.

It would do the whole pattern just fine, as long as you didn't mind landing in the middle for your pit man to change batteries!

Watts rating is too loose -- I can beat that in a minute just by mistreating the motor. Ditto battery ratings.

I'd say pick an easy-to-prove measurement, like battery weight, then just stand back and let technology advance. Maybe specify battery weight and say it has to be of a type that's known to be rechargeable. Or specify the all up power system weight (motor, ESC, battery). Then stand back and let the rule-benders bend: the rest of us have fun with whatever events drop out of the mix.

The only alternative that I can think of would be to pick a battery size and connector, and let event organizers supply the batteries -- except that, first, it'll be a pain in the behind for organizers, and second, technology will advance, the specified batteries will be obsolete, and it won't be fun for anyone.

Larry Renger · « **Reply #18 on:** December 26, 2025, 06:11:20 AM »

Why not just specify a maximum wing area and weight. Say 250 sq. in. and 12 ounces. Typical numbers for a current state of the art 1/2A or 1cc model. 🤠

Ken Culbertson · « **Reply #19 on:** December 26, 2025, 07:33:33 AM »

Quote from: Larry Renger on December 26, 2025, 06:11:20 AM

Why not just specify a maximum wing area and weight. Say 250 sq. in. and 12 ounces. Typical numbers for a current state of the art 1/2A or 1cc model. 🤠

personally, I do not think this will ever become more than a local fun event. If that is the case we should be a bit more liberal in the definitions. For outdoor electric use something in the range of a 2310 size motor on a 3s battery is perfect. Problem is that this motor on a 6s will perform like a '60's .35. That is the problem with electric sizes. The range is astronomical. 250sq" will be a bit small to carry the weight through square corners since the weight of the power train could easily exceed the airframe. I would like a larger range of say 18-20oz and 300 sq". Having said that, this is probably the only way to effectively define the class and I think that your range is more realistic. I will redesign my current project to 250sq" and pray for a light 3s battery!.

Ken

Dan McEntee · « **Reply #20 on:** December 26, 2025, 08:49:11 AM »

Quote from: Ken Culbertson on December 25, 2025, 04:31:16 PM

If "rules" are made for 1/2a electric (assuming there still is such a thing) eliminating the extra lap do you think a 3s 1100 would work? Is there any guide somewhere that defines what a 1/2a electric is? Do we use the Watts rating perhaps? I was planning to build for a 3s 2320 motor. Too big?

Ken

Ken

You need to time your flights, allowing two laps between maneuvers, just because you are used to that, I think. Your lap times will be much shorter, so your total time for a complete pattern will be less. In what I explained about what I'm running using I/C in the other thread, flight times don't exceed 6 minuets, if I'm remembering correctly, and that's for 2 laps or more tween tricks and doing the full pattern. Having enough time to do the full patter with some safety laps thrown in there was part of my goal for what I'm working on. Anything less just doesn't interest me.
Type at you later,
Dan McEntee

Larry Renger · « **Reply #21 on:** December 26, 2025, 09:52:00 AM »

As I recall, the pattern is exactly 60 lap equivalent. So, 5 second laps take 5 minutes. 🤠

Tim Wescott · « **Reply #22 on:** December 26, 2025, 10:03:56 AM »

Quote from: Larry Renger on December 26, 2025, 06:11:20 AM

Why not just specify a maximum wing area and weight. Say 250 sq. in. and 12 ounces. Typical numbers for a current state of the art 1/2A or 1cc model. 🤠

Thank you Larry. That's perfect.

I'm good at recognizing simple solutions to problems and adopting them, and I'm good at solving problems that need complicated solutions. Note the gap between those two...

Larry Renger · « **Reply #23 on:** December 26, 2025, 05:40:19 PM »

Quote from: Ken Culbertson on December 26, 2025, 07:33:33 AM

personally, I do not think this will ever become more than a local fun event. If that is the case we should be a bit more liberal in the definitions. For outdoor electric use something in the range of a 2310 size motor on a 3s battery is perfect. Problem is that this motor on a 6s will perform like a '60's .35. That is the problem with electric sizes. The range is astronomical. 250sq" will be a bit small to carry the weight through square corners since the weight of the power train could easily exceed the airframe. I would like a larger range of say 18-20oz and 300 sq". Having said that, this is probably the only way to effectively define the class and I think that your range is more realistic. I will redesign my current project to 250sq" and pray for a light 3s battery!.

Ken

what you are proposing should be a nice flying model, but is about equivalent to .15 power, definitely not 1/2 A.

Ken Culbertson · « **Reply #24 on:** December 26, 2025, 09:40:41 PM »

Quote from: Larry Renger on December 26, 2025, 05:40:19 PM

what you are proposing should be a nice flying model, but is about equivalent to .15 power, definitely not 1/2 A.

You are right, I was confusing the 2320 which I have run at 10,000 using a 10-6. Certainly, you did not mean a Fox .15! Happy New Year - Ken