Re: CEF speed contest Design Discussions

pkrankow Wed Nov 20, 2013 7:26 pm

roddie wrote:I'm hoping that good balancing and an ample elevator will permit non-eventful high-speed landings. This gear arrangement places the struts at right angles to the wing, on the leading edge and raked 10 deg. forward. Shock-loads should theoretically be distributed more "linear" to improve tracking. By comparison; an inverted "V" (music-wire) main-gear will twist both struts off-axis, with either or both wheels being loaded.

Maybe I'll end up with the well-known "Spitfire's" gear issues; when being modeled as a flying scale subject. I hope not...

All I can find about the gear is it was a rather narrow track, which was not considered an issue flying from grass fields that were essentially square so the planes were always landing or taking off into the wind.

Phil

edit: apparently the narrow track also caused uncontrollable "ground loops" while taxiing due in part to the closeness of the wheels to the CG.

roddie Wed Nov 20, 2013 8:36 pm

pkrankow wrote:
roddie wrote:I'm hoping that good balancing and an ample elevator will permit non-eventful high-speed landings. This gear arrangement places the struts at right angles to the wing, on the leading edge and raked 10 deg. forward. Shock-loads should theoretically be distributed more "linear" to improve tracking. By comparison; an inverted "V" (music-wire) main-gear will twist both struts off-axis, with either or both wheels being loaded.

Maybe I'll end up with the well-known "Spitfire's" gear issues; when being modeled as a flying scale subject. I hope not...
All I can find about the gear is it was a rather narrow track, which was not considered an issue flying from grass fields that were essentially square so the planes were always landing or taking off into the wind.

Phil

I assume too much sometimes... when talking 1/2A landing gear; I've generally used 1/16" dia. music-wire. Larger models have been using more rigid "Duralumin" gear for decades... and is widely available. It's a better choice for a lot of reasons... but you may have to fabricate it yourself for this application.

Phil, a scale gear's "track-width" for your AG model is approx. 20% of the w/s; however you choose to design it. What I feel is important, is the gear's integrity. It has to be strong, lightweight and distribute shock/load forces in a "linear" fashion; without inducing yaw on take-off or landing.

Something like this might work well... would look more scale-like and it's inexpensive.

http://brodak.com/tapered-flat-aluminum-landing-gear-blank-1-32-x-3-4-x-8.html

You could cut it in half and re-bend/drill for mounting to plywood fuse doublers... and use #2 x 3/4"L. machine-screws/nuts for the axles.

JPvelo Wed Nov 20, 2013 11:45 pm

Starting to look like a Super Corsair. Well, pieces of a Super Corsair...

Jim CEF speed contest Design Discussions - Page 4 AlRqC5f

JPvelo Thu Nov 21, 2013 1:43 am

OVERLORD wrote:Great site, Jim. A few days ago, I looked at pictures of the Tsunami, also mentioned on this site.

Below the CL version: 1 picture, 2 birds

Lieven

That's a great plane Lieven. Are you planning on building it?

Jim

JPvelo Thu Nov 21, 2013 1:56 am

Sneak preview:
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OVERLORD Thu Nov 21, 2013 2:02 am

Hi Jim,

No not at the moment. I started building another one already. It'll be a racer as well. The main wood parts are cut. Just need to find the time to continue. I saw the pictures of your plane when I was writing this post. Looks real good, and this IS a Corsair indeed.

Lieven

roddie Thu Nov 21, 2013 6:16 am

JPvelo wrote:Sneak preview:

Looks fabulous Jim!!! I can understand your dilemma with scale-like gear now.

I'm trying to visualize a bell-crank/lead-out arrangement for that wing... Maybe a perpendicular 1/8" plywood bell-crank plate mounted in the fuse just above the wing's cathedral panel, with lead-out "eyelets" at the extreme wing-tip would work... without inducing stress on the angled wing-joint? Two Cents

JPvelo Thu Nov 21, 2013 12:11 pm

roddie wrote:
JPvelo wrote:Sneak preview:

Looks fabulous Jim!!! I can understand your dilemma with scale-like gear now.

I'm trying to visualize a bell-crank/lead-out arrangement for that wing... Maybe a perpendicular 1/8" plywood bell-crank plate mounted in the fuse just above the wing's cathedral panel, with lead-out "eyelets" at the extreme wing-tip would work... without inducing stress on the angled wing-joint?

That's the plan. The plane I'm doing had flat plate wing tips that extend past the actual wing all the way around.
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I will make them of 1/32 ply and drill for lead out guides.

pkrankow Thu Nov 21, 2013 2:13 pm

I thought about slotting the fuse for the bellcrank but ended up not. Replacing part of the thinner sheeting with ply was just too easy. On the super corsair I doubt you have any other choice that will work well.

I hope you have a plan for stiffeners in those joints. Maybe some plywood sawn into slots?

I need to weigh my model still.

Phil

JPvelo Thu Nov 21, 2013 2:18 pm

pkrankow wrote:I thought about slotting the fuse for the bellcrank but ended up not. Replacing part of the thinner sheeting with ply was just too easy. On the super corsair I doubt you have any other choice that will work well.

I hope you have a plan for stiffeners in those joints. Maybe some plywood sawn into slots?

I need to weigh my model still.

Phil

I am going to glass the bottom of the joints and the trailing edge as well.

Jim

**Cribbs74** Thu Nov 21, 2013 2:41 pm

I'd show a picture of mine, but a couple pieces of uncut sheet balsa doesn't look like much.

I will say I am doing a Spitfire though.

duke.johnson Thu Nov 21, 2013 2:52 pm

Cribbs74 wrote:I'd show a picture of mine, but a couple pieces of uncut sheet balsa doesn't look like much.

I will say I am doing a Spitfire though.

I'm keeping up with you Ron. lol!

I did cut thefuse for one plane last night. But I don't know if I'll use it for the contest. I'm going to build the RC Gee Bee that I liked so much also. For the contest, I might go with and P-40. I do like the Spitfire too. It is one of the best looking planes our British friends ever made. And it looks fast, which should help. lol!

JPvelo Thu Nov 21, 2013 3:23 pm

duke.johnson wrote:
Cribbs74 wrote:I'd show a picture of mine, but a couple pieces of uncut sheet balsa doesn't look like much.

I will say I am doing a Spitfire though.
I'm keeping up with you Ron.

I did cut thefuse for one plane last night. But I don't know if I'll use it for the contest. I'm going to build the RC Gee Bee that I liked so much also. For the contest, I might go with and P-40. I do like the Spitfire too. It is one of the best looking planes our British friends ever made. And it looks fast, which should help.

You could always do a Supermarine Spitefull, the spitfires baby brother:
CEF speed contest Design Discussions - Page 4 4xK5nEl

roddie Thu Nov 21, 2013 4:26 pm

My F8F-2 has a serious nose-heavy condition with the Babe-Bee Shocked

although it's a bit premature to make that determination without paint, push-rod, tailgear etc... I am glad I left myself a little room in the length... because it looks like I may go with a "horseshoe" back-plate. The cowl should be a better fit with a shorter engine too. I'll need to re-drill my firewall anyway... and then I can make the choice later on.

That's what makes this contest such a challenge... Thumbs Up

pkrankow Thu Nov 21, 2013 5:13 pm

roddie wrote:My F8F-2 has a serious nose-heavy condition with the Babe-Bee although it's a bit premature to make that determination without paint, push-rod, tailgear etc... I am glad I left myself a little room in the length... because it looks like I may go with a "horseshoe" back-plate. The cowl should be a better fit with a shorter engine too. I'll need to re-drill my firewall anyway... and then I can make the choice later on.

That's what makes this contest such a challenge...

I'm crazy nose heavy too. Generous paint can make it tail heavy in a hurry.

Phil

batjac Thu Nov 21, 2013 8:05 pm

pkrankow wrote:I think the elevator is getting Monokote as an expedient.

Phil

Actually, that'd be scale, too. Many of the WW II warbirds had metal covered wings/tail surfaces, with fabric covered elevators, rudders, and ailerons. You're just following suit...

The Suitable Mark

batjac Thu Nov 21, 2013 8:08 pm

JPvelo wrote:You could always do a Supermarine Spitefull, the spitfires baby brother:

I've always liked the Spiteful better than the Spirfire. Also designated as the Seafang. Maybe it's because of my Navy heritage.

The Wet Feet Mark

pkrankow Thu Nov 21, 2013 8:29 pm

batjac wrote:
pkrankow wrote:I think the elevator is getting Monokote as an expedient.

Phil
Actually, that'd be scale, too. Many of the WW II warbirds had metal covered wings/tail surfaces, with fabric covered elevators, rudders, and ailerons. You're just following suit...

The Suitable Mark

Well, yea, but I am modeling a modern crop duster that has metal control surfaces.

I do agree that many WWII era aircraft had fabric skinned control surfaces, a large number of prototypes and early versions on both sides of the war are reported this way.

Phil

(anyways I lost the elevator and might need to make a new one.)

duke.johnson Thu Nov 21, 2013 10:11 pm

[/quote]
Nice looking plane also.

roddie Fri Nov 22, 2013 2:17 am

pkrankow wrote:
roddie wrote:My F8F-2 has a serious nose-heavy condition with the Babe-Bee although it's a bit premature to make that determination without paint, push-rod, tailgear etc... I am glad I left myself a little room in the length... because it looks like I may go with a "horseshoe" back-plate. The cowl should be a better fit with a shorter engine too. I'll need to re-drill my firewall anyway... and then I can make the choice later on.

That's what makes this contest such a challenge...
I'm crazy nose heavy too. Generous paint can make it tail heavy in a hurry.

Phil

There's a couple of ways we can effectively deal with c/g issues even after the model is built and painted. Remember... "nose-heavy" will fly... and we're going in a straight-line. With models this size on 42' lines... we'll need to offset the drag of the control lines. Anyone building "super-light" is not going to meet their speed potential. If you designed for a 5cc "tanked" engine; you can switch to a "horse-shoe" style back-plate alone... which places the engine cylinder "back" 1/4" and an external "wedge" tank can be mounted further back too. Drill your firewall with both patterns, and you'll have a choice. If you're still nose-heavy, obtain or make a pair of lightweight wheels... (they only have to work once...) An .062" Music-wire push-rod weighs about 4-5 times that of a carbon fiber push-rod. Glue sm. steel washer(s) to your tail-wheel if you have to.

OVERLORD Fri Nov 22, 2013 6:25 am

I started building as well. I cut fuselage, wings and stab.

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I didn't know how to start cutting the slot for the wing 'cause I never built a profile fuse before. I think, in general you first drill a hole and then start cutting with a saw. In fact I should buy one of those machines. I ended up chiselling it out which worked rather well.

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CEF speed contest Design Discussions - Page 4 Imgp5811

All fits together quite well.

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Lieven

duke.johnson Fri Nov 22, 2013 8:54 am

Looking really nice Lieven!

pkrankow Fri Nov 22, 2013 9:38 am

Very nice! I got a couple pictures up in the Traveling Prop thread, I'll repost the links here.

My building board staged with extra stuff I am working on. (flite streaks)

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Oh, current weight as pictured 123g or 4.3 oz. Trim paint, elevator, fuel system and controls are needed.

Phil

OVERLORD Fri Nov 22, 2013 9:45 am

Thanks. When I was sitting in my car at the traffic lights, I realized I forgot to mention what plane it was. It will be the 1936 Greve Trophy and Thompson trophy winner, the Caudron C460 "Rafale" s/nr 6909. Vive la France!!

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CEF speed contest Design Discussions - Page 4 Caudro10

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This plane crashed on 19 Dec. in the same year during a record speed attempt.

But there's more, and this also confirmed my choise, in 2008 or so, a Californian workshop decided to build a replica of the C460. So it's now sort of Franco-Américain.

https://www.youtube.com/watch?v=ekG_jy7RhiM&list=PLD7E2942CA91CA6FA

Lieven

duke.johnson Fri Nov 22, 2013 9:50 am

Looks really fast. Are you going with the same paint scheme?

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