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1/5 scale Bell P-39 Aircobra... - 1/5/2006 12:16:38 AM   
Darrell B.



Posts: 375
Joined: 12/22/2003
From: Rogers, AR, USA
Status: offline 		Well I finally have had some time to start my new project and thought that I would post a couple of pictires. I am building Jim Pepino's 1/5 scale Bell P-39 Aircobra. It will have an 80.5 inch wing span. I am uncertain of the AUW at this time, but I will weigh things as they progress and let you all know. Here are a couple of beginning pictures of the fuselage construction. I chose to cut out the parts my self so it is taking a little extra time. So far things seem to be working out quite well, and the plans look top notch. I hope that I don't regret saying that.,

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RE: 1/5 scale Bell P-39 Aircobra... - 1/5/2006 3:02:38 AM   
Darrell B.



Posts: 375
Joined: 12/22/2003
From: Rogers, AR, USA
Status: offline 		Sorry for the slow start!

Here are a few more pictures of my fuselage build on the P-39.

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< Message edited by Darrell B. -- 1/5/2006 3:04:17 AM >

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RE: 1/5 scale Bell P-39 Aircobra... - 1/5/2006 3:06:31 AM   
Darrell B.



Posts: 375
Joined: 12/22/2003
From: Rogers, AR, USA
Status: offline 		more!


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RE: 1/5 scale Bell P-39 Aircobra... - 1/5/2006 5:15:22 AM   
rrudytoo



Posts: 641
Joined: 12/23/2002
From: Simpsonville, SC, USA
Status: offline 		Hey Darrell,

Now here's a refreshing change of pace! I've seen this plan offered but shyed away due to some unknowns. Mainly, I don't know anyone who built a design by Jim Pepino nor do I know where to get things like the canopy and fiberglass parts. Is there a current list of suppliers for these parts supplied on the plans?

What do you plan to power your Airacobra with? Will you be using the Robart retracts for the Palmer P-63 or is there another set available? Any thoughts of putting the engine in the original, mid-ship position?

Good luck, Darrell, and I'll follow along with your build.

Al

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To wives and sweethearts. May they never meet.

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RE: 1/5 scale Bell P-39 Aircobra... - 1/5/2006 1:18:59 PM   
Darrell B.



Posts: 375
Joined: 12/22/2003
From: Rogers, AR, USA
Status: offline 		Al,

Let's see if I can answer your questions;

We have a couple of guys in our club that build off of Pepino's plans. One of them is building a Waco right now , and after looking at his plans, that was what pushed me over the fence to order these. They all seem to be nice airplanes. So far, it seems to be build very nicely, but not over built.

The suppliers listed on the plans are all out of business. These were drawn back in the early 90's. I talked with Craig at Fiberglas Specialties, and I am trying to make an origional cowl, worthy of copying, and he said that he would make me a fiberglass one. There isn't a canope available, but the plans do give instructions on how to build one.
The bigest challenge for me is going to be the engine exhausts and the air scoop on the top.

Robart makes a set of retracts that they just call P-39. They are close, but I am working with them to come up with a set that will fit into the plane better, and hopefully look more scale. Keep your fingers crossed, and we'll see.

I have thought about looking at building this with the engine in the origional mid engine configuration, but there are some huge cooling issues. I just don't know right now about this, and which motor to power it with. There are several out there, and more comming that will fly this airplane quite easily.

I would appreciate any and all comments about ths airplane, or my techniques, or suggestions on any issues discussed here. Thansk for your interest?

Best Regards,
Darrell

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RE: 1/5 scale Bell P-39 Aircobra... - 1/5/2006 1:29:06 PM   
a65l



Posts: 1468
Joined: 12/7/2003
From: va veach, VA, USA
Status: offline 		I beleive the Robart retracts for the P-39 are for the Top Flite kit, and would probablly be too small for yours.

Please keep the pictures coming.... I'm getting motivated to start a build project.....

Andy

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All others pay cash.

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RE: 1/5 scale Bell P-39 Aircobra... - 1/5/2006 2:05:33 PM   
Darrell B.



Posts: 375
Joined: 12/22/2003
From: Rogers, AR, USA
Status: offline 		Andy,

Here is a link to the ones that I'm using. They are supposed to fit the Consolidated P-39. The part number is #P-39.

http://www.robart.com/retracts/Custom.aspx

The only problem with them is that the nose gear strut is 1/2 inch to long. They are working with me to make one shorter for my application.

Watch out, or you will catch the building bug!!!

Good Luck,
Darrell

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       Post #: 7

RE: 1/5 scale Bell P-39 Aircobra... - 1/6/2006 5:51:38 AM   
rrudytoo



Posts: 641
Joined: 12/23/2002
From: Simpsonville, SC, USA
Status: offline 		Darrell,

I didn't know about the Robart part# P-39 retracts. Those are PERFECT! As for the canopy and, possibly, the exhaust manifolds, those could be made by vacuum forming. I haven't tried that process yet but it seems easy enough once a suitable mold is made.

I bought a set of exhaust manifolds for a Ziroli Stuka from a fellow who made a master from balsa wood and then made the mold from a kit purchased from Micro Mark. The resulting resin manifolds are beautiful to look at with simulated welds cast in. Trust me, this will be the last of your concerns!

Not too long ago there was a guy who was featured in RCM for scratch building a 1/5th scale P-63 with a mid-mount engine. I talked with him over the phone and learned that he used a Moki 2.10 for power. This made real sense as a Moki uses no nitro and alcohol burns relatively cool. He utilized the original dorsal carb intake and the cooling ducts in the wing roots to bring in cool air and vented the heated air via space between the simulated exhaust manifolds and the fuselage walls in addition to the doors (shutters) under the fuselage utilized by the full-scale P-39 and P-63 to control engine temperature. He claimed that he never had an over-heating condition with this configuration.

He said that the Moki made more than enough power and that he flew his plane at half throttle most of the time. Full throttle brought the plane well beyond scale flight speeds due to the streamlining of the Airacobra and he cautioned that the plane did not scrub off speed quickly.

He used a shaft from the Moki's crankshaft to the prop drive washer that was made using tool steel. His weak link was the Woodruff key in this shaft. He said that the Moki was prone to "kicking" during starting and that the hard "kicks" were sufficient to shear the key and damage the shaft. (I'm guessing here but I think he may have used a collar to act as a union between the drive shaft and the Moki's crankshaft.)

I might be willing to give this combination a try. The only area I would deviate in would be in a threaded connection from the drive shaft to the engine's crankshaft. I have a Moki 1.80 sitting around waiting for something to do. Who knows?

Enough of my verbage. I'm excited to see your progress, Darrell. Keep up the great work!

Al

< Message edited by rrudytoo -- 1/6/2006 5:54:07 AM >

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RE: 1/5 scale Bell P-39 Aircobra... - 1/6/2006 6:49:49 AM   
Canuck1



Posts: 1046
Joined: 7/1/2002
From: Edmonton, AB,
Status: online 		Good luck with your project. Keep the pics coming.

Craig.

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RE: 1/5 scale Bell P-39 Aircobra... - 1/6/2006 1:31:30 PM   
TLH101



Posts: 5439
Joined: 12/27/2001
From: Corpus Christi, TX, USA
Status: online 		Hey guys, keep in mind the Consoladated P-39 is much larger than the Pepino. I have a Consoladated, and had a Pepino kit. When you look at the Robart gear, be sure to check out the drawings listed on the site see if they will fit. The problem with the P-39 is the nose wheel retracts partially into the leading edge of the wing, and if you get too long a strut, it will be a big problem. Also, if you try to make the main gear retact "scale" toward the rear of the wing, you will have a problem with getting the wheel inside the thinner portion of the wing, due to the gear needing to rotate about 15 degrees. I dont thing that rotation is built into the Robart gear, or any other for that matter.

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Terry
"Old Fart" in training. (not to be an R/Cer, but to be an "Old Fart")

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RE: 1/5 scale Bell P-39 Aircobra... - 1/6/2006 1:55:14 PM   
grbaker



Posts: 2420
Joined: 12/12/2001
From: Houston, TX, USA
Status: offline 		Great project! It's my favorite warbird.

Once I get some other projects out of my way, I'll refurbish my DCM 1/5 scale P-39C. Powered by a 3W60 with Spring Air retracts and Lyte Flight struts. Pic in my gallery.

BTW - I'll go with a different exhaust system when I rebuild it. That muffler is just too ugly. Anyone had any luck using canisters inside the fuse like the 3D guys use?

< Message edited by grbaker -- 1/6/2006 1:58:10 PM >

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RE: 1/5 scale Bell P-39 Aircobra... - 1/6/2006 2:16:33 PM   
Darrell B.



Posts: 375
Joined: 12/22/2003
From: Rogers, AR, USA
Status: offline 		Terry,

I have been e-mailing with Gary at Robart and we have come up with what I think is the solution to both of these issues. First off, I am having the front strut made half an inch shorter than the Consolidated to just barely clear the #4 former. I couldn't justify cutting it since it is the one that the wing plugs into. I am also going to mount the retract assembly a little flatter than Pepino had his, and half an inch lower to account for the loss of strut length when the nose gear is extended.

For the mains, we came up with using the retract bodies for the Midwest AT6. They have a 9 degree angle built into them that when mounted facing backwards will move the wheels back some when retracted, no rotation required. I will mount them in the scale location, right behind the main wing spar, and then when the wheels extend or retract there won't be any change in the CG. I think that this was the best solution to this issue.

Anyway, I have them on order, and should be hearing something on them in the next week or so. The P-39 struts are not stock so they have to work them into their regular production schedule. I'm not sure how Robart does it, but if they are like most cottage industries. they have a regular routine, but it is easy, interesting, and sometimes fun to work special projects into their shcedule to break up the monotony.

I spent a couple of hours with Craig at Fiberglass Specialties the other day. Craig is a great guy, and realy gave me a good tour of his facility. If I can ever get a plug made for the cowl on this bird, he is going to make a mold for it. I'm really hoping to get started on this soon. This is why I built the fuselage first. I have since started working on the horizontal stab, and will post a couple of pictures as soon as I get something to look at. Ok here is one to tease you with.

Best Regards,
Darrell

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< Message edited by Darrell B. -- 1/6/2006 2:17:44 PM >

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RE: 1/5 scale Bell P-39 Aircobra... - 1/6/2006 3:12:35 PM   
TLH101



Posts: 5439
Joined: 12/27/2001
From: Corpus Christi, TX, USA
Status: online 		Darrell,
I think you may be onto something there. I have a set of the Robart T-6 gear from a Midwest Texan I am restoring, and a set of Pepino's plans, so I took some shots that may help you out. Looks like you will need slightly longer struts that a yoke for larger wheels, and a set of 85degree blocks on the gear, but other wise it should work. The wont be swept quite to the scale location when retracted, but will be pretty darn close. Also, since the legs are positioned away from the air cylinder when retracted, you can the have struts made with scale scissor location.
Feel free to use these pics as needed, and send to Robart if you want.
Terry

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