David Eichstedt

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I've just started on my giant Hangar 9 P-47, and have decided to do some cosmetic surgery. I'm converting it to a Bubbletop version.

Seems like this might be a useful thread for those who want their Hangar 9 Jug to look a little different than most of the others out there.

So far the process has been very simple, with no surprises hiding under the Ultracote. This kit is well-designed and well-built, which has made the mod go smoothly.

Please don't expect me to have a finished model in two weeks. The bubbletop mods are going very fast, but I'm going to put some time into the new finish of the model. It may take me a couple of months to get it done.

Now, on to the photos!

Flanker

David Eichstedt

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Step 1: strip off the Ultracote from the razorback area. Feel the sides to determine where the convex fuselage either flattens or turns concave, and mark those locations with a Sharpie. Use a straightedge to connect those marks, then mark another line about 1/2 inch outboard / downward, then cut the Ultracote at that line.

Step 2: cut through the sheeting at the first line you made in Step 1, and peel away the sheeting. Try not to completely destroy the sheeting, as it will come in handy in a few steps. Notice the spine that's built from T-shaped plywood and a balsa cap.

Step 3: remove the spine. Do not destroy the spine in the process, as you will want to use it to make a new spine later on.

David Eichstedt

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Step 4: using a pencil, draw a curved line on each bulkhead as a guide for cutting and sanding the bulkhead to its new shape. Hangar 9 has conveniently made the bulkheads ring-shaped, which gives the modeler an easy reference for drawing this line. For this kit, the line doesn't have to be extremely accurate. Plus or minus 1/16 might even be close enough at this stage.

Step 5: using a razor saw, cut away most of the excess bulkhead. Don't cut right to the line at this point.

Step 6: use a dremel tool with a sanding drum to carefully sand the bulkheads to the line created in Step 4. A sanding block may be used to check the relative curvature of each bulkhead and to do any final touch-ups.

Step 7: use the sheeting removed from the Razorback to mark a series of points on the forward, angled bulkhead (at the hatch cutout). This could also be done with a stiff steel rule, but I didn't have any of those handy. (No crude comments here, please)

Step 8: again using a razor saw and a dremel, remove the excess portions of the angled bulkhead.

The results to this point should look something like this last photo, with all four bulkheads appearing nicely rounded and ready for the next steps.

David Eichstedt

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Step 9: bridge the gap in the angled bulkhead with some 1/8 lite ply and sand to shape.

Step 10: IMPORTANT STEP! build a new spine using the plywood pieces from the old spine. I was able to re-use the old pieces for the three aft bays, but I had to build new pieces for the bay just behind the angled bulkhead. I cut the balsa cap off the old spine and sanded the top of the T-section flat.

Building a new spine is important for at least one practical reason: when working on your model inverted in a cradle, you don't want to crush the fuselage sheeting aft of the canopy.

Step 11: (not shown) use 3/16 inch square balsa to form a lip on the inside edge of the fuselage sheeting, effectively forming a new stringer on each side of the fuselage. This step will ease the installation of the new sheeting by forming something like a lap joint and not relying on merely an edge joint to join the old sheeting to the new sheeting.

Step 12: Sheet the area with 3/32 balsa. Don't worry too much about gaps between the sheeting--they can be filled with filler just prior to re-covering.

Viola! You're over halfway done! Next up, the hatch.

TLH101

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Looking pretty good. What canopy have you found that is a correct fit?

David Eichstedt

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The Aerotech canopy appears to be the right size. Their kit wingspan is 82", while this one is 81 1/4. For a standoff scale kit, that's close enough.

Connery

I'm sure it'll look good when finished. What color scheme are you going to change it to since the "checktail clan" never flew bubbletops?

David Eichstedt

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Except with the name "Elizabeth" instead of "Earnestyne"

Maximus-RCU

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Cool, I'm doing the exact same thing. I'm kind of weird I guess, never could stand the razorback jug and prefer the "B" & "C" model Mustang to the bubble. I guess I'm just bass akwards. I'm using the Top-Flite canopy. It is a little smaller than the Aerotech I believe even though the plane is bigger. 14.25" long 5.5" wide. I'm thinking it will work.

Later,

Maximus

Doolittleraider

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You sick b@##ard! What kind of individual takes a perfectly good arf and does that?
It looks great so far and I am anxious to see it done. I think many here appreciate your step by step instructions so they can follow in your footsteps. Its a great flier you will enjoy it!
Here I am taking an P-51 arf that could have been an covered and ready to fly a long time ago I decided to buy it without covering and fiberglass it I guess I am as sick as you.....

Connery

Should look real nice. I almost used one of the black/yellow checkered cowl schemes for me TF Thunderbolt as well.

David Eichstedt

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Onward, with the hatch!

Step 13: Place the hatch on the fuselage and trace the outline of the new aft fuselage shape onto the angled hatch former.

Step 14: Again using the inner contour of the former as a guide, draw the new contour for the second hatch former. Note how I'm using my middle finger as a jig for keeping the pencil tip the same distance from the inner contour of the former in question. This is a simple but effective technique I learned from an old-time NASA Dryden sheet metal shop technician.

Step 15: Use a straightedge to help mark the new shape for the forward hatch former, which is actually the aft cockpit former.

Step 17: Make a rough cut through all the formers using a razor saw, and through the balsa sheeting with an X-Acto knife. If you do it right you can remove the razorback in one piece.

David Eichstedt

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Step 18: Sand down to the lines you just drew on each former using a Dremel tool with a sanding drum. Note that you'll have to create a new set of lines for the aft, angled former, parallel to the ones you drew previously spaced at about 1/8 inch.

Step 19: Fill the gap in the angled former using 1/8 inch lite ply and sand to the proper shape. Through Steps 18 and 19, a sanding block should be used to ensure you're keeping the rounded contours smooth. I used a sanding block for all the final contouring, especially as I was getting the angled former to match the new of the fuselage.

Step 20: Install stringers from 3/16 inch square balsa to assist in sheeting the hatch. I used 2 inch wide, 3/32 inch balsa, because that's what I had laying around. If you have 3 inch wide stock, you can get by with a single stringer down the top center of the hatch. No need to build a load-bearing spine in this section if you install stringers.

Step 21: Sheet the hatch, sand to final shape. Be sure to leave enough overhang past the angled former!

Your structural modifications are complete! Wasn't that easy? You may now re-cover the aircraft as you desire. The last step will be to glue the new canopy in place using RC 56. I won't get to that step for a long time. If you want to see how it turns out, you might want to subscribe to this thread so you'll get a notification by email.

David Eichstedt

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Since I can never wait to see how a new project is going to look, I had to get out the canopy and hold it in place.

This is an Aerotech canopy, and it's untouched at this point. Once it's trimmed to shape, it will rest about 1.2 inches lower than seen here. Once you make that visual adjustment, it looks like it's going to be perfect for this kit.

The next shot shows the FPE 2.4 I'm going to use for power, and approximately where it sits in relation to the firewall. Yesterday I built a mockup from lite ply and Styrofoam then sent it off to JTEC for them to build a custom muffler that will fit entirely within the cowl. No giant holes in MY cowl.

Last, I can't take all the credit for this mod. I had a couple of little helpers along the way.

Baldeagle

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Flanker thanks for posting. I have a Northwest hobby tech p47 that I plan on going the other way. I prefer the razor back. Is there any other difference between the Bubble and the Razorback? Is the vert fin the same? Thanks Rich

David Eichstedt

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Rich,

That depends upon what version of bubbletop you have. All the Ds have the same tail and wing, although some of the later Ds have a dorsal fin added in front of the vertical. The N version has a different wing with increased chord and squared-off wingtips--you won't want to put a razorback fuselage with that wing.

What color scheme do you plan on doing?

Flanker

Baldeagle

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Flanker I haven't started the p47 yet , next fall I hope. I will have to get my kit out and see which wing it has . I really don't know which one I will do as of yet.
I am trying to get all my old projects that I have started done. I am working on a P51 That I started about 12 years ago. 1/5 Pica. It is almost ready to paint. Thanks for the info. Rich

David Eichstedt

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Here are some updated photos.

Turns out Al at JTec needed a mockup of the muffler itself, not the engine cavity! Here are some shots of the mockup I made out of scrap wood laying around the garage.

David Eichstedt

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And here are some shots of the finished muffler from JTec.

This custom muffler was only $119. I'm really happy with the result! Notice how I didn't have to hog a huge chunk out of the engine box.

I still have to trim the exhaust tubes down about 3 1/2 inches.

DLEVETT

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I know this thread is old but, how did the FPE 2.4 work out in the H9 P-47?
I really like the custom Jtec muffler and would like to bash one into a Bubbletop just like yours if I can find one for sale NIB.

Dave

JohnVH

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Nice work! Subscribed!

DLEVETT

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Hey John,
Your doing a nice job on your TF P-47 rework.
I,ve got a Saito 220 thats been looking for a home for quite some time now and figure this H9 P-47 will work nicely.
The TF GS P-47 ARF is awesome but is a little to big for the Saito, so this one should be a better option.
Now I,ve just gotta find one.

Dave

David Eichstedt

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Wow, it's been a long time since an update! Can you believe I'm still working on this project? It's been set aside for a couple years since moving to the Midwest. I got a bunch done over the recent Christmas break, however, and I'm hoping to have it done for this year's flying season.

The whole airplane has been sprayed with Chrome Aluminum Krylon and buffed panel-by-panel to give an awesome aluminum appearance. Thanks to Bob Frey for sending me the instructions for how to do this. I'm halfway through painting the invasion stripes at the moment. I still need to paint the cowl, paint & install the cockpit kit & dummy engine, and move on to final assembly. I'm sticking with the 353rd Fighter Group scheme I posted 3 years ago in post #8.

The FPE was sold with the muffler, and I've gone for a Saito FG-36 instead. This required cutting a couple inches off the engine box and installing a new firewall. I work for Horizon now so I had to go with one of our house brands.

If I can get it done, I'm toying with taking it to the AMA Scale Nats this summer. I've never competed, so I'm pretty sure my legs would turn to jello and my thumbs would shake uncontrollably during my first flight round!

DLEVETT

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Hi,
Thats interesting as I,ve got the Saito 220 glow version looking for a home.
Do you have any pics to share with us?
How about the Krylon instructions is it possible to share them as well?
One last question for you, does H9 plan on rereleasing this model?
Once I found out it wasn,t available anymore I listed my 220 for sale.
I was planning on going with the TF GS P-47, but if its coming out again I,ll keep the 220 as it seems I,m going to take a bath on it in order to sell it.

thx
Dave

David Eichstedt

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So this is resurrecting an ancient, crusty thread.

I finally finished my airplane. It didn't actually take this much work, I just didn't work on it for so many years.

Finally settled on a G45 for the engine. I figured the FG-36 was going to be anemic compared to what I'm used to now. Luckily the firewall mods to fit the FG-36 worked out perfectly to mount the G45. I also fitted some Robart air retracts instead.