kpd

I recently picked up a Jemco P-39 and will begin building soon. The 'plans' are just as described as for the P-51 - top view of the wing and a sheet of instructions for everything else. I'll be starting a build thread in a few days over on the other groups of rc modeler's forum.

Super08

My Feedback: (2)

I sure wish someone would bring this fun to fly series of warbirds back.

jjscott

If I built another one of these I would add half ribs between each rib. The spacing is very wide and I had a lot of "scalloping" or sagging of the covering between ribs.

Jim

buzzard bait

Kpd, it would be a great contribution to scan those plans and also do a scan of the ribs and formers after cutting them out of the sheets, then post to Outerzone and let us know they are there. I know it's some work, because I did it for the Mark's Models SE-5A; all I can say is it would make a lot of guys very happy if you did.

In any case, it will be nice to see your thread on it.

Jim

spaceworm

Re the SE 5, are the plans you did up on Outerzone? i really want to buld one. Thanks.

I have the Marks Pitts kit with the Jedelsky wing. I will try to scan the parts and post them.

Richard

buzzard bait

Yes, the SE-5A plans are on Outerzone, right here... http://outerzone.co.uk/plan_details.asp?ID=6135

The photo is mine. It would be great to have your Pitts too.

And the P-39. Here is the Jemco Mustang: http://outerzone.co.uk/plan_details.asp?ID=5572

Jim

kpd

Yes I am tracing the parts for the p-39 and will upload everything to outerzone when I have them all.

My build is over at http://www.rcgroups.com/forums/showthread.php?t=2638117

Hope it is OK to link over there.

I would like to provide a way for others to have a canopy if they build from the templates. Anyone have any ideas on a good way to accomplish this?

A second question I guess, any opinions on replacing the sheet tail surfaces with built-up ones?

buzzard bait

kpd, thanks so much for offering to trace the P-39 parts and put it all on outerzone. Regarding the canopy, are you going to make a plug from the canopy you have? That would be wonderful!

The OP did make a plug and sold some canopies; I bought two of them and they are excellent. I'm sure he could advise you about his method.

If you do that, then I think the way to make them available would be to contact Parkflyer Plastics at...

https://parkflyerplastics.com/cart/i...age=contact_us

In fact, I would do that BEFORE trying to make a plug, because he (Keith?) wants a certain material, I believe. Then they could sell them, and you could make a note to outerzone that they are available there. He might make you a deal to pull a couple good canopies for you in exchange for the plug.

That would really bring this plane back for scratch builders.

Jim

kpd

Jim, thanks - we think alike as I have no interest nor experience in pulling plugs so I was thinking of maybe sending the cockpit over to Keith to make a mold/plug and provide them.

Edit: Just sent a note to ParkFlyer plastics to see what he thinks.

kpd

Keith got back to me, He's preparing some information for people that want to create molds for him. That's good to hear. In the meantime, I am going to try my own hand at making a mold using "Durham's Water Putty" based on the results of some googling.

Main construction of the wing is nearly done.

buzzard bait

I often use Durham's Water Putty for filling holes and dings. I'll be interested in how you do a plug with it, and how it comes out.

Also, Keith's info will be good to have. I have an old Reed Falcon kit with a deeply yellowed canopy. I'd like to know how to do a plug and get a clear canopy, and make it available to others through Keith. It's a big one, though.

Jim

kpd

How does the Mark's Models SE-5a fly? I have an old Lanier RC balsa ARF that is roughly the same size. It's a great flying plane.

buzzard bait

Unfortunately it was terrible, which I think was due to the weight. I used an OS 26 FS with a 10x4 prop and it just didn't give it enough speed. I wound up crashing it twice because it was very hard to control, flying, I think, at the edge of a stall. The cabanes broke and I never did repairs. If I were doing it again I would lighten it up as much as I could. I would also use a 10x5 prop, hoping for a little more speed, or go with a 2 stroke 25 for more power. It looked great, so I have thought about doing one from scratch.

Jim

kpd

Sorry to hear that. The wingspan on the lanier is 38". I use the same size prop you did, but with electric so I have no idea how that would compare.

Here's a photo:

buzzard bait

Here's my Marks SE-5A:

kpd

I like the looks of it. The picture on Outerzone of it was resized fairly small so you can't see the details.

spaceworm

Are the wings the same as the Pitts? I have the pitts kit and understand it is a bear to fly. I am thinking of building an SE5a from scratch. Also thinking of building up the wings with ribs, etc., hoping for a lighter weight. Also planning on using a Saito FA-56. Whadya think?

Thanks

buzzard bait

My understanding is that Marks Models kitted Thornburg's Honker Bipe, but it didn't sell, so they came up with a series of semi-scale bipes, SE-5A, Fokker D-7, Pitts, using the same wing design. There were some gliders using that simple thick sheet Jedelski wing also. Thornburg would choose his wood carefully, but that probably goes out the door when you're trying to make a living selling kits.

Ironically, the semi-scale WWII types like the Mustang, P-39 and Spitfire were very light, but the biplanes were heavy because they were based on thick sheet wings.

I was hoping my SE-5A would be OK because of the undercamber, but there was just not enough lift. If I build this again I would use a completely different wing structure and try to keep it simple and light. I think light weight is really important, but especially for smaller types like these. That's why the Mustang was so great...it weighed about half what anyone else's 40 size Mustang weighs.

Please don't go putting a Saito 56 on a WWI bipe this size. It will fly at a scale speed of 400 mph and look totally wrong. Build it light and use a light engine. With a span of 42 inches, this bipe is not even 1/7th scale. People typically use a 50 size four stroke in 1/6th scale, which will generally come out to about 52 to 56 inches in span. In my opinion, even that is overpowered. I used a much less powerful 40 diesel swinging a 13 inch prop on my VK Nieuport 17, which turned it about 7500 rpm, and it flew it beautifully.

The Marks bipe designs are nice and simple, so I would come up with a simpler wing, maybe traditional Jedelsky using light sheet and exposed ribs, and use a 21 to 30 size four stroke. If I went to the trouble of a full built up wing then I would want a more scale like design anyway. The virtue of the Marks designs is their simplicity, yet good looks in the air. I'd keep it that way.

Jim

.50cal

dionysusbacchus, sent you a pm. I know this is an old thread but I am trying to get a few of your Canopies. Also what size motors did you put in these P51s. Thanks Kevin

E-Challenged

Like many of you I built a series of Mark's Dynaflite and Jemco P51 Fun Mustangs, all .40 glow powered and modified for to be more scale-like. One was based on Hoover's "Ole Yeller" and another on Wisconsin Air National Guard planes that we kids watched maneuver out at Mitchell field outside of Milwaukee, Wi. One of them was clocked by radar doing 70mph, as I recall the tail wagged. They were extremely easy to fly and quite aerobatic.I have kits of the Fun Scale P-51 and P-40 out in the shed. They will eventually be built with electric power.