Jemco P-47 Razorback (Full Version)

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BadSplice -> Jemco P-47 Razorback (1/29/2011 10:58 PM)

I was recently given this kit by a friend in my flying club. We were talking about building, and ARFs vs Kits, and I was saying that at this point in my career, I have plenty of planes to fly, and I am much more interested in building a nice scale kit than assembling another ARF. So he offered me a Jemco .40 sized P-47 kit he had, (made in 1979 and designed by Jim Meister according to the plans) and I am totally stoked to be getting started on it.
This kit is interestingly designed. It has a built up fuse, and foam core wings (new for me) and almost none of it is to be built over the plans. I had the plans scanned anyway, and I will refer to the computer screen for most of what I need. Any templates that were meant to be cut out of the plans will be traced from the copies and printed out. I also set up my camera in such a way as to capture parts straight on, and against a grid for scale, and shot in all the die cut plywood pieces, and the ends of the foam core blanks. My goal is to record enough info to be able to reproduce parts or even build the whole plane again. (the one snag in that being all the molded plastic goodies that go with it)
As far as I can tell, all the parts are accounted for and in good shape, with the exception of the cowl. Over the years it has deformed some, and has an odd depression molded into both sides from heat and/or pressure. I have never done it before, but I am considering making it into a plug, so that I can then make a female mold from that to produce a new cowl out of fiberglass. Its just such a detailed part. Perhaps I will start with one of the simpler parts.
The kit includes the parts for making 2 1000lb bombs and a center drop tank, the pylons for the bombs, the razorback, and a turbocharger (yeah?) exit on the bottom rear of the fuse. Also the clear canopy, which is pristine. It provides in the plans for scale opening supercharger exits on the sides which I plan to do, a scale exhaust exit at the rear of the fuse I do not, a sliding canopy I am not sure about yet, and I'm toying with making the cowl flaps operate. In the instructions, it says that the prototype flew well, even at 9 1/2 lbs, but I think I can do a lot of scale detail and still keep it well under that with modern materials and hardware. I have a Zero of about the same size that weighs 7 1/2 lbs, and it handles great.
So far, I have inventoried and marked all the parts, removed all the die cut parts from their frames, and traced out everything that cant be copied off the plans. (just as a note, I checked several of the parts against the original plans, and they fit perfectly, so I have confidence I can reproduce accurately from them) I debated building up a cradle to set the fuse frame on during assembly, but since I will not need it long, and only for this, I opted to use "mini sawhorses" made out of taped together CD cases... Since my table is flat, and the CD cases all the same, it actually sits very flat and straight. I have gotten as far now as attaching all the fuse formers to the frame. F-1 is epoxied on, 2-9 are tacked on with CA, and 10 is wood glued, with some balsa added to it for the hinge to bite into later.
I just wanted to get this thread going, since it is a fairly rare kit. (I looked, and hardly found any info on it) If anyone wants to chime in with their experience and comments please feel free :) This is my first real build thread. I have put together and repaired quite a few ARFs, and I have built a Great Planes Spirit 100 sailplane kit, and most of an old IM products CAP 21 kit. I fancy myself a decent craftsman, and don't foresee having too much trouble with this kit, but I hope to learn a lot doing it.

Some pics so far



BadSplice -> RE: Jemco P-47 Razorback (1/29/2011 11:07 PM)

Some pics of the canopy, cowl, and other parts.



Ram-bro -> RE: Jemco P-47 Razorback (1/29/2011 11:45 PM)

I lovethe old Jemco kits. I used to own the P47, built the Hellcat and have his D9 somewhere in the collection. You definetly dont want to use a 40 on this plane. .....way underpowered. These kits are great builder kits and guys who want to try their hand at a scale project. The P47 gives you alot of detail to play with....but that adds weight but hae fun with it, you wont be disappointed



shanksow -> RE: Jemco P-47 Razorback (1/30/2011 4:07 AM)

I wished the Jemco kits could be updated and sold in the modern era. I sold off a F-4U Corsair kit that I had.



ram3500-RCU -> RE: Jemco P-47 Razorback (1/30/2011 7:02 AM)

Here is the one I built years agao, still waiting to be finished. Some day.[8D]

Very scale kit, with great detail. I found it to be fun to build.



Ram-bro -> RE: Jemco P-47 Razorback (1/30/2011 7:11 AM)

Heck, I just saw the one that I built is fordale here on RCU.......



BadSplice -> RE: Jemco P-47 Razorback (1/31/2011 5:58 AM)

Nice looking aluminum finish Ram! Is that paint or foil?

Quite honestly, I'm not sure why this kit got phased out. Not because of the design I would think. I haven't started on the wing yet, but it looks really straightforward, just a normal foam core setup. The fuselage is going together really fast, and is not at all hard to get straight.

I have the formers all glued in place, and most of the stringers in. The first part of the intercooler door tracks are installed, and the fuse frame cut away where the doors will go. Before I get the sheeting on, I still need to rout the pushrods for the elevator and tailwheel, and pull-pull wires for the rudder. (I wanted to do all hidden linkages but with the rudder and elev. hinge lines on the same plane it would be really tricky to achieve) Also its time to install the intercooler doors. I made one up out of lithoplate aluminum, using carbon tubes for the guide posts. It seems to work fine, but I have a couple of decisions to make.

Are the doors supposed to be flush with the outer skin when closed? or are they recessed? I cant find a good pic of this anywhere, ( I suppose in the grand scheme of things that if I cant really see exactly how it is in the pics Ive seen, it will be scale enough however I do it ;) Its just nice to know these things)

The plans suggest having the doors spring loaded, and tied by a cable to either the throttle or retract servo. My first impression would be that tying it to the throttle would provide the most scale like movement. It just worries me that the throttle servo would have to work against the springs. Also, if done as suggested and spring loaded to close (which is supposed to be the full throttle position) if the servo failed the springs could drag the motor to full throttle.

That brings me to another point, I can understand why the cowl flaps close at full throttle and open at idle, partly since they still leave a gap when closed, and because of the increased air pressure at full throttle. A) do the intercooler doors actually close at full throttle? and B) if so, is there a gap or do they close all the way?

Another thing I'm considering is replacing the fuse sheeting with much thinner stock. The original sides are really thick... 3/16". The structure is already fairly stiff with no sheeting on it at all, and I plan to glass and paint the plane. I'm thinking I should go down to 3/32" or even 1/16" sheeting. (or I suppose I could plane down the original sides... it would be tedious but it would save buying the wood. Too bad I don't have a laser capable of just splitting one of the sheets into 2 thin ones ;) )



ram3500-RCU -> RE: Jemco P-47 Razorback (1/31/2011 6:46 AM)


quote:

ORIGINAL: BadSplice

Nice looking aluminum finish Ram! Is that paint or foil?

Quite honestly, I'm not sure why this kit got phased out. Not because of the design I would think. I haven't started on the wing yet, but it looks really straightforward, just a normal foam core setup. The fuselage is going together really fast, and is not at all hard to get straight.

I have the formers all glued in place, and most of the stringers in. The first part of the intercooler door tracks are installed, and the fuse frame cut away where the doors will go. Before I get the sheeting on, I still need to rout the pushrods for the elevator and tailwheel, and pull-pull wires for the rudder. (I wanted to do all hidden linkages but with the rudder and elev. hinge lines on the same plane it would be really tricky to achieve) Also its time to install the intercooler doors. I made one up out of lithoplate aluminum, using carbon tubes for the guide posts. It seems to work fine, but I have a couple of decisions to make.

Are the doors supposed to be flush with the outer skin when closed? or are they recessed? I cant find a good pic of this anywhere, ( I suppose in the grand scheme of things that if I cant really see exactly how it is in the pics Ive seen, it will be scale enough however I do it ;) Its just nice to know these things)

The plans suggest having the doors spring loaded, and tied by a cable to either the throttle or retract servo. My first impression would be that tying it to the throttle would provide the most scale like movement. It just worries me that the throttle servo would have to work against the springs. Also, if done as suggested and spring loaded to close (which is supposed to be the full throttle position) if the servo failed the springs could drag the motor to full throttle.

That brings me to another point, I can understand why the cowl flaps close at full throttle and open at idle, partly since they still leave a gap when closed, and because of the increased air pressure at full throttle. A) do the intercooler doors actually close at full throttle? and B) if so, is there a gap or do they close all the way?

Another thing I'm considering is replacing the fuse sheeting with much thinner stock. The original sides are really thick... 3/16''. The structure is already fairly stiff with no sheeting on it at all, and I plan to glass and paint the plane. I'm thinking I should go down to 3/32'' or even 1/16'' sheeting. (or I suppose I could plane down the original sides... it would be tedious but it would save buying the wood. Too bad I don't have a laser capable of just splitting one of the sheets into 2 thin ones ;) )

Years ago, when I started this build, a product called Presto was available. It was self-adhesive, but far less sophisticated than the aluminum foils we have now. That is what I used on this P-47. Each scale panel was individually cut out and applied. The whole system is lighter because it didn't require glassing as does the foils we use today.

I did go with the spring system they show on the inter-cooler doors, and it works. (the doors are flush) I used the most powerful servo we had at the time (65oz I think), and it works fine, yoked to the throttle. Open at low throttle, closed at high. These doors expelled hot air exchanged from the inter-cooler, as needed. Kinda like the waste gate for the exhaust. At altitude, as I understand it, there would have been little or no hot air to expel, so these doors would have been closed.

I also have an aluminum tube running all the way back to the turbo shroud where the actual engine exhaust leaves the plane, as it would have altitude.

Hope some of this helps. This is a cool little plane.



BadSplice -> RE: Jemco P-47 Razorback (1/31/2011 7:00 AM)

Thanks, that does indeed help! I will get to work on the spring system for those doors. I was tempted to use the scale rear exhaust, but I really want to save as much weight as possible by keeping the tail really light. I'm even planning on building up all new tail surfaces, and seeing if I can get it lighter than the solid sheet ones. (the wood feels pretty heavy)

I like the aluminum look, but I think I'm going to go with paint. Mostly because I recently got an airbrush, so I must use it :p Im not sure if I will do panel lines, since the plane is so small, (only 1/9 scale) I'm not sure I could make them small enough to look right. Rivets are right out. Not sure what sort of scheme to use yet, but I want to have the nose art be a bearded god hurling a lightning bolt, and the name "Thor's Hammer". I did some searching, and couldn't find any indication of a P-47 named that, though it seems the most obvious possible name for a THUNDERBOLT to me :p



blkbird -> RE: Jemco P-47 Razorback (2/1/2011 5:49 AM)

"Years ago, when I started this build, a product called Presto was available. It was self-adhesive, but far less sophisticated than the aluminum foils we have now. That is what I used on this P-47. Each scale panel was individually cut out and applied. The whole system is lighter because it didn't require glassing as does the foils we use today.

I did go with the spring system they show on the inter-cooler doors, and it works.(the doors are flush) I used the most powerful servo we had at the time (65oz I think), and it works fine, yoked to the throttle. Open at low throttle, closed at high. These doors expelled hot air exchanged from the inter-cooler, as needed. Kinda like the waste gate for the exhaust. At altitude, as I understand it, there would have been little or no hot air to expel, so these doors would have been closed.

I also have an aluminum tube running all the way back to the turbo shroud where the actual engine exhaust leaves the plane, as it would have altitude.

Hope some of this helps. This is a cool little plane. "

ram3500-RCU ..........got any pics???!!!



ram3500-RCU -> RE: Jemco P-47 Razorback (2/1/2011 6:03 AM)


quote:

ORIGINAL: blkbird

''Years ago, when I started this build, a product called Presto was available. It was self-adhesive, but far less sophisticated than the aluminum foils we have now. That is what I used on this P-47. Each scale panel was individually cut out and applied. The whole system is lighter because it didn't require glassing as does the foils we use today.

I did go with the spring system they show on the inter-cooler doors, and it works.(the doors are flush) I used the most powerful servo we had at the time (65oz I think), and it works fine, yoked to the throttle. Open at low throttle, closed at high. These doors expelled hot air exchanged from the inter-cooler, as needed. Kinda like the waste gate for the exhaust. At altitude, as I understand it, there would have been little or no hot air to expel, so these doors would have been closed.

I also have an aluminum tube running all the way back to the turbo shroud where the actual engine exhaust leaves the plane, as it would have altitude.

Hope some of this helps. This is a cool little plane. ''

ram3500-RCU ..........got any pics???!!!

Unfortunately, this was long before RCU, digital cameras, and build threads, for me. I didn't document builds back then, like I do now. I can take pictures of her from the out side, the inter-cooler door mechanism is hidden in the aft. i think the cables mat be visible at the servo end. I'll take a look. Been a long time since I had the wing off.



blkbird -> RE: Jemco P-47 Razorback (2/1/2011 6:11 AM)

ram3500-RCU...you're the greatest!!



ram3500-RCU -> RE: Jemco P-47 Razorback (2/1/2011 6:26 AM)


quote:

ORIGINAL: blkbird

ram3500-RCU...you're the greatest!!

[:)]



BadSplice -> RE: Jemco P-47 Razorback (5/22/2011 1:08 AM)

Well, I have made some progress. The fuse is almost done, and the tail is mostly built. I need to finish the hidden linkage for the elevator (need to make a cavity in the rudder still) Made a lot of progress on the cockpit. Got the wings sheeted, and there I ran into a problem.

Nothing went wrong with getting the sheeting on. In fact, I found the whole process of preparing the cores and skinning the wing to be easier than just putting the skins onto a built up wing... But now that I'm to the point of cutting out the retract bays and servo boxes, I'm thinking I should have come up with some extra reinforcing inside the wing.

I was hoping to make scaleish flaps that extended back as well as down, and was looking into mechanisms for that. But when I got the skins on the wing, and looked at how much of the lower skin would have to be removed near the root to accommodate all that, Im having doubts. As is, with the landing gear doors drawn on, if I put a servo cover from a different plane on the wing for reference, it shows how little of the skin is left. If I then remove some extra T.E. material to make room for the larger scale flap... well.....

Have I built myself into a corner here? Is there a way to make the wing strong enough or do I need to re think how I am going to do the flaps altogether?



BadSplice -> RE: Jemco P-47 Razorback (5/22/2011 1:14 AM)

a few more pics:



SCALECRAFT -> RE: Jemco P-47 Razorback (5/22/2011 5:24 AM)

I have had almost all the Jemco models. They are some of the most durable airframes i have ever built. I still have my built and flown P-47 in storage. I had a fox 74 I think in it. Spring airs, flaps, supercharger air exits wired into the throttle servo and retractable tail wheel and sliding canopy.

I think I was at around 8.5 lbs. Covered with solartex and painted.

It is a very forgiving model if CG'ed properly. it will require nose weight.

My buddy molded the entire model in glass. I molded the entire Corsair.

Fibergalss masters have the Cowl.

Enjoy the model.

Steve

Mine



chistech -> RE: Jemco P-47 Razorback (5/24/2011 2:56 AM)

I just got this kit a couple of months ago. I will be building it the end of this year. I'm currently building an old Ziroli designed 40 size bubble top P47 right now. Building is almost done. Does anyone have the retract mounting instructions that were offered from Jemco for this plane? I picked up a Saito 72 for this and I'm hoping it should be enough for good scale like flight. I will be doing glass and paint. I will be using Hitec 225's to help keep the weight down. I will be watching your progress.



mobyal -> RE: Jemco P-47 Razorback (5/24/2011 4:59 AM)

Just found this thread and suscribed. What a neat project. I built the JEMCO Zero back in the mid-70s and a flying buddy built the Hellcat. Fun builds and we used to have a lot of fun flying them.
Re the intercooler doors you mentioned in your post above. Don't know if you've worked them out yet, but the attached photos may help. Looks to be pretty clear that they're flush, or very close to it, when closed. Have a bunch more of cowling, ehhaust, oil cooler, gear and flaps if you're interested.
Keep up the good work!
Al
Al



chistech -> RE: Jemco P-47 Razorback (5/24/2011 6:10 AM)

Were those pictures of the Hun Hunter taken at the Tennessee Museum of Aviation? I remember seeing 2 P47's there including one with a working supercharger. Pretty nice museum for sure and a lot of the planes are in flying condition and flown right out of the hanger quite often. My wife got to sit in the cockpit of the one of the planes and they even have the cockpit of the B25 used in the movie with John Wayne and Kirk Douglas," In Harms Way".



mobyal -> RE: Jemco P-47 Razorback (5/24/2011 2:00 PM)

Yep. That's where I took 'em. The time I was there when I took the pics they had a PBY from Fl in there. Said it comes up there every year during hurricane season. Also had the Hellcat from Planes of fame that two days later was destroyed in a crash.
Good museum.



fidoav8r -> RE: Jemco P-47 Razorback (1/18/2013 9:11 AM)

Hello BadSplice,
Im getting ready to start building my Jemco P47D that has been in the box for 20 plus years. 
What retracts do you plan to use. I also want to use a gas engine.. Any thoughts.



chistech -> RE: Jemco P-47 Razorback (1/19/2013 5:37 AM)

I just recently purchased a set of the Jemco retract plans for this plane. Once I start mine I will post the build here. I can tell you on the retract plans that they didn't provide for much in the way of retract mount support. I will be adding some sort of additional support for the mounts.



Prekin -> RE: Jemco P-47 Razorback (1/19/2013 8:15 AM)

Hi all,
I check this thread, because I´d like to build a Top Flite Giant P-47. Now I thinking about the paint scheme and Thunderbolt´s covering.
I like "ram3500-RCU´s" Razorback, here is the picture.
Any idea how to achieve the metal look?
Thanks for every idea!



glazier808 -> RE: Jemco P-47 Razorback (1/19/2013 2:42 PM)

"Years ago, when I started this build, a product called Presto was available. It was self-adhesive, but far less sophisticated than the aluminum foils we have now. That is what I used on this P-47. Each scale panel was individually cut out and applied. The whole system is lighter because it didn't require glassing as does the foils we use today. "

I don't think that presto is still available, there are quite a number of foil tapes offered today.  Also HVAC tape works very well.  I've used this for areas that I'll chip back to show aluminum.

Casey



John Redman -> RE: Jemco P-47 Razorback (1/19/2013 3:10 PM)

Try this link for the intercooler door operation.

http://m.youtube.com/watch?v=4CPv0MSaVyg



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