Boeing Y1B-17 Project--1/48th Scale

[Second Air Force]

The filler you see on the bomber is Testors Model Master Red Putty. I like it as it dries relatively quickly (except if applied very thickly) and sands easily. The same basic product is also found in automobile body shop supply stores here in the U.S. and is often called "spot putty". The material is actually red oxide lacquer primer in a paste form. The only drawback to using this stuff is that the lacquer component in it tends to attack thin plastic sheet a bit.

I've had this tube for over ten years and it is still working well.

[No.1]

Aha- sounds good, if it is nitro based, thus better, as well it adhere excellent to surface

[Second Air Force]

Yes, it has very good adhesion. I decided to see if it is easily available but it seems that Testors may have quit carrying it.  I have also used Squadron Green Putty and it is quite good also but seems to dry out in the tube a little faster.

Scott

[Jicehem]

Oh ! Very important modification. That will be very amazing.

Cheers,

Jicehem

[Second Air Force]

I decided to jump around a little to show some of the other parts I've been collecting for this project.

The YB was equipped with R-1820-33s, somewhat different appearing than the -97. After looking through some boxes I remembered that the SBD used much the same engine. In fact, the SBD-1 and 2 used a -32. I just happened to have one from an Accurate Miniatures SBD-1 that I was able to mold and cast in resin.
B-17 kit engine on the left, new -33 on the right:

Boeing Y1B-17 Project--1/48th Scale

The propellers on the early Forts were the narrow-chord version, and the old AMT A-20 kit has the exact propeller needed. I also cast these in resin and put the resin props in the A-20 kits for later. Koster also makes a really nice narrow-chord Hamilton Standard that I have reserved for a PB4Y-2 planned for the future.

Boeing Y1B-17 Project--1/48th Scale

And here is the engine cowled up with the new propeller on it next to the Monogram parts:

Boeing Y1B-17 Project--1/48th Scale

Scott

[Second Air Force]

I had a few free minutes tonight and that gave me a chance to start on the intake/exhaust fairings that are a distinctive part of the Y1B-17 nacelle. On the real machine the intake for the carburetor is at the leading edge of the long fairing. Here is a really good photo from the Amarillo Mechanic School showing the intake duct and part of the exhaust system with the fairing removed:

Boeing Y1B-17 Project--1/48th Scale

The air that didn't go into the carb intake was ducted aft and appears to have acted as an augmenter, or at least as cooling air, for the exhaust. The collector ring exhaust pipe came up the right side of the nacelle, was routed into the long duct, and dumped at the end of the nacelle fairing. These two photos show the first fairing on #2 nacelle. I made the duct by splitting an aluminum tube lengthwise and shaping it as needed. To complete the installation I still need to build the intake duct and the collector ring exhaust pipe:

Boeing Y1B-17 Project--1/48th Scale

Boeing Y1B-17 Project--1/48th Scale

Scott

[No.1]

Wonderful work!!!

[mfg495]

Excellent work, I cannot wait to see the finial model 

[Second Air Force]

Thanks for the support and interest in this project, everyone! My modeling works at a pretty slow pace due to a lack of time, but it gives me enthusiasm when I share the work with fellow modelers. Once we get the 1/1 scale B-17 flying I hope to have a bit more time to devote to this 1/48th version .

Scott

[Second Air Force]

Another nacelle update. I had some free time again this evening to devote to the exhaust system so I built the fairing for #1.
One of the little details on the YBs was the exhaust stack that runs at an angle from the engine collector ring up into the exhaust fairing. You can see the #1 exhaust pipe is installed in this photo and the trough for the #2 installation is marked with black ink. The outboard engines used a different routing than the inboards for some reason, and all four angled exhaust stacks are on the right side of the engines. The inboard ring cowls are cut back to allow room for the exhaust while the outboards are not.

Boeing Y1B-17 Project--1/48th Scale

And here's a close-up of #1 that shows the exhaust pipe more clearly, with a photo of a "real" #1 nacelle below the model.

Boeing Y1B-17 Project--1/48th Scale

I'll have several more tall tales to tell about the nacelles that I must save for later.
Scott

[Letipapa]

Exhillirating!

[Second Air Force]

Here is a continuation of the engine nacelle story. (I did this work last year, so things are not in chronological order. )

The YB-17s used a different design nacelle and engine mounting structure than all later Fortresses. One of the differences was the length of the nacelles. The outer ones are a bit longer than later Forts and the inners are shorter. Here is the beginning of the modifications--cutting off the firewalls and removing a bit of material. I then added material to the outboards to lengthen them the appropriate amount.

Boeing Y1B-17 Project--1/48th Scale

The right wing has been modified in this photo. Notice how much closer together the propeller arcs are to one another on the YB wing versus the standard B-17G on the left.

Boeing Y1B-17 Project--1/48th Scale

Another feature of the early airplanes was a lack of cowl flaps. The front end of the nacelle is rounded to let the air flow out of the aft end of the ring cowls. Here is the early effort at reshaping the lip and adding appropriate firewalls.

Boeing Y1B-17 Project--1/48th Scale

All of the putty you see is part of the work involved in eliminating the exhaust system and various turbocharger ducting on the bottom of the wing.

Scott

[Second Air Force]

Next was the #2 and 3 nacelle interiors. The 299 and YBs used a totally different engine/nacelle support structure than all the later models. On the B and forward the nacelle is fully monocoque with the skin, stringers, and frames supporting the entire load. On the 299/YB there is a truss from the wing structure to the firewall that supports the engine mounts. Here are a couple of reference photos to show the truss. The bottom picture is the development of the Y1B-17A showing the early turbocharger mounting on top of the wing.

Boeing Y1B-17 Project--1/48th Scale

Here are both nacelles with the trusses constructed. All the plumbing and other details will be installed just before the wing halves are glued together. The long white half-tube at the top of the nacelles is the trough that housed the exhaust system on the real airplane.

Boeing Y1B-17 Project--1/48th Scale

Here are the ring cowls in progress. I simply removed the engines from the cowl flap section and glued the cowls to the flap rings. There is some reshaping of the front of the cowls that I will do on the lathe later.

Boeing Y1B-17 Project--1/48th Scale

The o.d. ring is from the first B-17 kit I ever built, just after Monogram released it. I decided to incorporate it just for the sake of nostalgia.

Scott

[alaleksic]

Very nice model and great work

[Letipapa]

This change of the nacelles length - great work, awesome!