Saturday, January 6

Construction Review PT I : P&W R-2800 Double Wasp & Separate display version from Magic Factory in 1/48th scale

Gary recently gave us a great (& much imitated) review of the Magic Factory 48th scale F4U-1A/2 Corsair kit. We now have three sets to compliment this mode, in the form of two full engines & a ground crew to service the aircraft (in tomorrow's story). Today he looks at the engines in his review...

Construction Review PT I : P&W R-2800 Double Wasp & Separate display version from Magic Factory in 1/48th scale

To accompany their recent F4U-1A/2 Corsair kit, Magic Factory have collaborated with Master Precision to produce a new series of 3D printed upgrade sets. In the first batch they will release three sets which focus on the Corsair engine and some ground crew figures, ideal for a maintenance vignette or part of a larger diorama:
-1/48 P&W R2800 (Separate display version) 3D print for Magic Factory F4U kit 5001 (7505)
-1/48 P&W R2800 (Maintenance version) 3D print for Magic Factory F4U kit 5001 (7506)
-1/48 F4U Ground service (5 figures) for Magic Factory F4U kit 5001 (7507)

Magic Factory have generously provided me with a set of pre-release prints for each set. This review  will look at the engines, while part II will look at the maintenance set in detail.

P&W R2800 - "Maintenance version" (for the Vought Corsair F4U-1A/2)
From Magic Factory
Kit No #7506
1/48th scale
3D printed resin kit
Price: $49USD from Hobbylink Japan
First up let's take a close look at the "Maintenance Version" of the new 3D printed P&W R2800 engine by Master Precision. They have designed the full Double Wasp engine complete with exhausts and ignition wiring. This set is designed to allow the engine to be attached to the aircraft with the cowling panels off allowing the engine interior to be visible.
The set consists of four parts, the engine itself, the cowling flaps (open only), the nose cowl ring and a support frame onto which the nose ring attaches. I was a little surprised that none of cowling panels are provided in the set.
The early F4U-1 and F4U-2 Corsairs were fitted with the Pratt and Whitney R-2800-8 Double Wasp engine. The -8 produced 2,000 hp (1,500 kW) at 2,700 rpm at 1,000 ft (300 m); 1,800 hp (1,300 kW) at 2,700 rpm at 15,500 ft (4,700 m). It was the first production "B" Series engine using a two-stage, two-speed supercharger and with internal engineering changes resulting in increased power and reliability.
I have almost run out of superlatives for describing the level of detail being achieved in 3D printing these days. There seems to be almost nothing which can't be designed digitally and physically printed using UV curing resin. I think the biggest challenge with using sets like these will be the painting, with all the detail parts in place.
As a reminder of what is provided in the kit plastic, here is the supplied engine from the Magic Factory kit 5001. As far as plastic kit engines go this is not too bad, but when compared to it's new 3D printed cousin looks very plain. Bear in mind that this engine was not designed to be displayed with the cowling off so the exhausts are mostly missing etc.
A closer look at the side of the engine reveals a high level of detailing which will be very visible on the finished model. The 3D print supports are very fine and this makes for a far easier job to remove them without causing damage to the parts themselves. The thought did pop into my head as to whether this engine could be used on other 1/48 Corsair kits such as those from Tamiya or Hobby Boss. I have not tested this so for the moment cannot comment further.
The interior of the open cowl flaps are nicely detailed, and a major step up from the corresponding kit plastic part. Alignment slots are included to make installation on the kit fuselage as easy as possible.
A page from the F4U maintenance manual shows the actuation system of cables and pulleys used on the cowl flaps. Whilst the 3D printed parts are certainly simplified I think in 1/48 they are more than adequate.
The forward cowl ring comes complete with internal structural ribbing and subtle panel lines.
The last piece of the puzzle is a frame on which the cowl ring attaches at the front whilst the rear end attaches to the cowl flaps. This part is central to the way that Master Precision has designed this set as it provides something for the forward ring to attach to. Unfortunately from my research it seems that much of this is inaccurate as the nose ring actually attaches to mounts on the forward cylinder tappet covers. More on this shortly...
Included with the set is a simple one page set of instructions. This shows how to modify the kit nose to accommodate the new resin parts.
With the kit plastic modified as shown (i.e. the center mounting plug for the kit plastic engine has been removed) the resin engine can be simply offered up and glued in place.
Once in place the detail on this engine really pops. The exhaust tubing fits snuggly into the fuselage cutouts on the bottom. 
You will want to attach the cowling flaps to the fuselage first as they don't really fit over the engine easily.
One small adjustment I made was to trim some plastic around the forward edge of the fuselage to allow the resin exhausts to slide properly in once the cowling flaps were installed. It only took 20 secs and makes life much easier.
In terms of accuracy, the only part of this set that I don't believe is correct are the four horizontal supports (stringers) positioned at the 12, 3, 6 and 9 positions. Whilst the Corsair cowling panels are split into four sections, it appears that where they meet (at those four compass point locations around the engine) there is no permanent frame onto which they bolt. Instead the cowling panels attach to the forward cowl ring and the rear cowl flaps. There is a cover which goes over each longitudinal join.
These two photos show quite clearly that when the center cowling panels are removed that no stringer framing is present. The forward cowl ring seems to float on the front of the engine but in reality it attaches to special mounts on the front bank of cylinder tappet covers.
Master Precision has made the understandable decision to use these imagined horizontal frames to secure the forward cowl ring. It's an easy way out rather than designing the fiddly mounting points on the cylinders. Unfortunately for me, once I see something like this I can't live with it, so I plan to cut the horizontal stringers away and make up my own brackets to secure the nose cowl ring.
An useful period photo of an F4U-1 Corsair nose during assembly. Notice that there is a horizontal internal support frame onto which the cowling panels attach but it is not permanent and once both cowling covers are removed it comes away as well.
Much of the R2800's dual cylinder banks is visible with the cowling covers removed. An easy fix for the incorrect stringers is to cut them away and leave the nose cowl ring off altogether. This will give the added benefit of revealing more of this lovely 3D printed engine.
If you do choose to cut off the stringers and still wish to mount the forward cowl ring then you will need to fabricate some brackets which attach to the cylinder tappet covers and the internal framing of the nose ring. This will be pretty fiddly work and will need to be accurate otherwise the nose ring will be offset or crooked.

P&W R2800 - Separate display version (for the Vought Corsair F4U-1A/2)
From Magic Factory
Kit No #7505
1/48th scale
3D printed resin kit
Price:$44 USD from Hobbylink Japan
The final set of the three that Magic Factory will be releasing is a "standalone" version of the R-2800. This set (7505) contains no parts for fitting the engine to the aircraft and would work best in a diorama with the engine sitting alongside the model. The rear section of the Double Wasp engine is provided in this set.

The front (main) engine part is identical to that used in the "on aircraft" set, 7506. The rear engine section is new and only found in this set 7505. When ordering make sure you select the right set for what you have in mind.
The P&W R-2800 was a complex piece of machinery. It's not often that modellers need to think about the rear of an engine but in this case it's interesting to get a feel for what parts are hidden behind all those cylinders. The R-2800 underwent many revisions during it's lifetime and each of these introduced subtle changes to the engine, as it was adapted to fit each aircraft.
The 3D design is once again wonderfully executed and printed in high resolution by Magic Factory. Support placement is thoughtful and makes cleanup and preparation for use that much easier.
With minimal cleanup the front and rear parts of the engine can be mated ready for painting and mounting. You will have to come up with your own frame to mount the engine on should you wish to display it outside the aircraft.
A useful side view of a R-2800 giving us some sense of the size of the full engine.
As no instructions are included, it's up to the modeller to make sure the alignment of the front and rear engine sections is correct. I say this because I just noticed that I have attached the rear section upside down and will need to rotate it 180 degree before final gluing !! 
The inclusion of one or two alignment notches would have been a welcome design by Magic Factory here.
It occurred to me that some modellers may want to use the 3D printed engine on the their model with the kit plastic cowling. This would enhance your model without breaking up the overall shape of the nose (as happens when you remove panels or cowling covers).
A quick test fit shows that the 3D part does indeed fit comfortably inside the plastic cowling so this is definitely a viable option.

CONCLUSION - P&W R-2800 Double Wasp & Separate display version from Magic Factory in 1/48th scale
These two upgrade sets are an excellent addition to Magic Factory's new tooled F4U-1A/2 Corsair kit. They are super simple to use, being direct drop-in replacements for the kit plastic parts. Overall I highly recommend these sets.

We will look at the ground crew sets tomorrow in Part II of this review...
Gary Wickham