78" Consolidated PB4Y-2 Privateer conversion from Flightline RC B-24 ARF - RC Groups
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Dec 27, 2017, 02:25 PM
Electric Coolhunter
Thomas B's Avatar
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78" Consolidated PB4Y-2 Privateer conversion from Flightline RC B-24 ARF


The introduction of the excellent new Flightline RC B-24 Liberator ARF was exciting to me for two reasons: I have always wanted a nice B-24 about this size for my WWII bomber collection, and I have always wanted to do a PB4Y-2 Privateer. Given that the Privateer is a modified and stretched B-24 with conventional tail surfaces, it is just not all that difficult to kitbash a B-24 into a Privateer.

References: besides the normal online sources, I am primarily using these two references:

1. Naval Fighters Number 93 Convair PB4Y-2/P4Y-2 Privateer book by Nicholas Veronico and Steve Ginter. :

https://www.amazon.com/Convair-PB4Y-...nter+privateer

2. The excellent 1/72 scale Warpaint PB4Y-2 drawings by Ian Huntley published in the old tabloid newspaper Aviation News in March 1982. My great flying buddy Richard Ng was kind enough to loan me a set of these drawings to reproduce for this project.

Here is a list of the conversion work needed and my basic plan for proceeding with each part.

1. Fuse stretch just in front of wing leading edge of 84" full scale, about 5" model scale. Approach: cut the model fuse and hatch, create a load bearing plywood and balsa structure to stretch the fuse and add foam as needed to blend to forward fuse to aft fuse.

2. New conventional vertical tail and horizontal tail. Approach: build up tail surfaces using conventional balsa construction. Design the assembly to use the existing mounting points for the horizontal tail. Design with hidden torque rods and bolt servos to bottom center of horizontal tail.

3. Create the different engine nacelles used on the Privateer. Approach: cut away existing B-24 nacelles at wing leading edge and rotate them 90 degrees. Sand, fill and blend rotated nacelles as needed to get a decent representation of the real thing. Remove\cover supercharger (not used on Privateer).

4. New Erco ball turret on nose. Approach: modify the stock H/J nose current chassis as needed. Create new vac form ball turret tooling and install with ply and balsa supports and detail with styrene interior details.

5. Add second upper turret. Approach: order and install spare part from Motion RC.

6. Add new left and right blister turrents with dual 50 cal guns. Approach: create vac form tooling for blister turrets, form parts, detail and install.

7. New paint and markings. Approach: prep airframe, spray and airbrush latex paint, order markings for " Tortilla Flats" from Callie Graphics.

That covers the major tasks.

The goal is to have the Privateer ready to fly by May 1, so it can attend Warbirds over Benbrook in mid May.

Not going for super scale. Going for "that looks good" and for a replica of the good looking aircraft in the attached picture.
Last edited by Thomas B; Dec 27, 2017 at 05:04 PM.
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Dec 27, 2017, 02:25 PM
Electric Coolhunter
Thomas B's Avatar
Started last night with nacelle and fuselage surgery on my silver B-24. Here are a couple of pictures of it post surgery, with nacelles rotated and the fuse stretched out about 5" for study purposes.

The thrust line will be about 1/4-3/8" lower than the B-24 with a slight impact on prop ground clearance. I think the only slightly tedious part of the conversion will be sculpting the old nacelle fairings into the new nacelle fairings.

Next steps: sculpt the nacelle fairings, reinstall rotated nacelles and design and build support structure for fuse stretch.

Too late to chicken out once the model is cut and trimmed...
Last edited by Thomas B; Dec 27, 2017 at 02:48 PM.
Dec 27, 2017, 02:27 PM
Electric Coolhunter
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Dec 27, 2017, 10:27 PM
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Veltro's Avatar
Looking forward to your posts, Thomas. I'm planning on doing a Privateer conversion, too, but it will be a few months before I can start.

These guys make acrylic domes that should work well for the ERCO bow turret: https://kitkraft.com/t/categories/acrylic-domes
Dec 28, 2017, 03:38 AM
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taz101's Avatar
Thomas, just for your reference, I took a quick photo of the B-24 nose with the HK's B-17 ball turret, to see if it could work (size wise) for you.

LURCH
Dec 28, 2017, 09:46 AM
Electric Coolhunter
Thomas B's Avatar
Quote:
Originally Posted by Veltro
Looking forward to your posts, Thomas. I'm planning on doing a Privateer conversion, too, but it will be a few months before I can start.

These guys make acrylic domes that should work well for the ERCO bow turret: https://kitkraft.com/t/categories/acrylic-domes
Great link and bookmarked it for future reference. I have already CADded up a half sphere with the side flats on it to accept the side turret supports and have a buddy that is going to CNC it for me shortly. Will either vac form it myself or get Sparky at Parkflyer Plastics to do it. I think I can make it a good bit lighter and thinner than the acrylic dome.

I am betting the Privateer will tend to be nose heavy with the stretch.

Picked up some scrap Ren tooling board yesterday to use to make the masters for the side blister turrets and the different bomb aimer transparency under the Erco ball turret.
Last edited by Thomas B; Dec 28, 2017 at 10:13 AM.
Dec 28, 2017, 10:06 AM
Electric Coolhunter
Thomas B's Avatar
Here is a quick pic of my Erco nose turret and forward fuselage drawings that I enlarged to model scale. The outer diameter of the ball works out to 3.25". The other picture shows the Freewing H/J nose overlaid over the drawing to highlight the various differences.

You can also see the bubble side windows for the pilot and copilot in the front view, plus the various radar fairings (no less than 8 of them, 2 hidden in this view). Will be vac forming all of these parts as well.

The last picture shows the fuse cross section after the surgery. A view the stock B-24 owners will hopefully never see on their own aircraft...
Last edited by Thomas B; Dec 28, 2017 at 10:42 AM.
Dec 28, 2017, 10:15 AM
Electric Coolhunter
Thomas B's Avatar
Quote:
Originally Posted by taz101
Thomas, just for your reference, I took a quick photo of the B-24 nose with the HK's B-17 ball turret, to see if it could work (size wise) for you.

LURCH
Thanks, Lurch. Little on the small side, but gives a good idea of the overall coolness of the Erco ball on the nose.
Latest blog entry: 2014 events and travel
Dec 28, 2017, 10:34 AM
Electric Coolhunter
Thomas B's Avatar
Here is one more picture of some of the enlarged drawings. This one gives an idea of the size of the massive vertical tail (a little over 13" tall, measured from the top of the horizontal tail) and the surprisingly large Erco 250TH waist turrets. A stock H/J nose and nose turret assembly is in the picture for scale.
Latest blog entry: 2014 events and travel
Dec 28, 2017, 10:51 AM
Electric Coolhunter
Thomas B's Avatar
By the way, this is the tool I used to slice off the fuse and nacelles. Super thin, super sharp, stainless steel and flexible:

https://www.amazon.com/gp/aw/d/B06XS...?ie=UTF8&psc=1

Nope the very clean edge cut on the fuse cross section picture above.

My wife does some clay sculpting and turned me on to them. A great tool for foam surgery. Only downside is that the sharp edge is so thin is is easy to bend or damage on anything harder than foam.
Latest blog entry: 2014 events and travel
Dec 28, 2017, 09:20 PM
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Dec 29, 2017, 11:31 AM
Electric Coolhunter
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Motion RC had the spare parts up on the web site and nearly all in stock this AM, so I ordered two spare cockpit haches (only way to get the upper turret, sigh,)

Ordered two as it looks like my buddy Richard Ng is going to convert his B-24 as well!

Also ordered a spare H/J nose turret. "Tortilla Flats" was actually a very early PB4Y-2 that still had the stock H/J nose turret. The Revell box art posted in the first post is actually incorrect. So, in addition to making the the much more interesting and impressive Erco ball turrent, I am also going to paint and decal the correct older turret for "Tortilla Flats". I will be able to swap from the great looking ball turret to the "correct" nose turret for this aircraft.

I will confess to taking yesterday evening and this morning off from the B-24s and Privateer to assemble and decal my Christmas present from my great wife Robin, which was a Freewing 80mm A-4 Skyhawk....
Last edited by Thomas B; Dec 29, 2017 at 11:54 AM.
Jan 01, 2018, 01:47 AM
Electric Coolhunter
Thomas B's Avatar
Tinkering on the nacelles tonight while half watching a movie with Robin. Too cold in the garage!

Turns out it is not enough to detach and rotate the front of the nacelles and re-attach. The motor is not mounted symmetrically in the nacelle opening. Will also have to dissemble the three foam pieces of the front of the nacelle, remove the motor mount and rotate it so that it is oriented like a stock B-24 then reassemble with foam glue. Not a big thing.

Have started sculpting and removing foam from the sides of the nacelle segments that stayed with the wing.

Currently out of Bestine rubber cement thinner (heptane) which will safely dissolve the type of foam glue used on the B-24, so ordered a can from Amazon tonight. Hopefully will have most nacelle mods completed by the weekend.

Also located the aft upper turret location on the fuse and marked the circle to Dremel out to drop the turret to the the correct height.
Last edited by Thomas B; Jan 01, 2018 at 01:59 AM.
Jan 03, 2018, 01:00 AM
Electric Coolhunter
Thomas B's Avatar
Disassembled the nacelle above into its three foam sections, rotated the motor mount in the nacelle, added some new slots and channeling needed for the motor mount to key into. Mount now locked in the new position. Reglued everything and here we are. Prop shaft now centered left to right in nacelle, slightly high of center as it is when in the stock B-24 cowl.

Using heptane to soften the glue is slow going. Took a little over an hour of repeatedly dripping it into the seams and slowly prying the foam apart to get it separated. Make sure you wear gloves and have excellent ventilation.

Three more to go.

Spare B-24 parts ordered late last week arrived today. Fantastic service from MRC.
Last edited by Thomas B; Jan 03, 2018 at 01:06 AM.
Jan 03, 2018, 01:42 PM
Oh no, not again!
jhspring's Avatar
Very impressive demonstration of kit-bashing, Thomas. This is coming together quickly. Very much enjoying following along.

Regards,
Jeff


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