INTRO
September 2020, I was looking for a new Warbird Fighter as a successor to my P-61 Black Widow Nightfighter.
My Douglas A-26B Invader, Scale 1/5,9th (Span 3,60m.= 142"), finished building in 2015, was the successor to my Warbird Bomber B-17 Flying Fortress (span 4,00m.=158”)
With my B-17 and P-61, I won over 25 International Scale contests all over Europe and 6x the European Star Cup (European Championships Stand-Off Scale, for models up to 25 Kg. With B-17 4x and the P-61 2x).
In any case, again it had to be one from World War 2 and at last I chose;
The Republic P-47 Thunderbolt Razorback. 1/5,7th Scale. (Span 2,21m.=87”).
PROTOTYPE & DOCUMENTATION.
The P-47 historical background;
The Republic P-47 Thunderbolt was the biggest and most heavily armed single-seater fighter of WW2. Its top speed and diving capability were impressive, thanks to its powerful Pratt & Whitney R-2800 engine and exhaust driven Turbo-Supercharger.
Its robust design and huge radial engine meant that the T-bolt could absorb an enormous amount of punishment. That was particularly important on dangerous ground-attack missions, where a stray bullet in the cooling system of a Spitfire or Mustang could bring down these both in-line powered aircraft with frightening speed. In contrast there are stories of P-47’s returning safely to their airfields with some entire cylinders blown off their P&W engines.
On the other hand, the portly lines of the P-47 were hardly as glamorous as some of its sleeker counterparts such as the P-51.
Indeed, the Thunderbolt was often referred to as the “Jug” as an abbreviation for “Juggernaut”.
The P-47 size and speed did create some problems. Firstly, it was thirsty. Its high fuel consumption meant that early versions could not escort Allied Bombers all the the way to their targets deep within the Third Reich, resulting in high bomber losses over Germany. Secondly, its climb and turning performance were inferior to its Allied and German contemporaries. Thirdly, the heavyweight “Jug” needed particularly long runways for take-off and landing. P-47 Variants;
The P-47B was the first Thunderbolt production variant. This model inherited some of the characteristics of the prototype, including fabric-covered control surfaces. The high-performance led to several accidents, before control surfaces were re-skinned with metal.
The P-47C received an 8” extension to the forward fuselage and a new deflector plate between the oil cooler and the waste gate.
It retained the short cowl flaps (with eight individual flaps), and the keel of the fuselage was flat. Many later P-47C’s were retrofitted with the so called “bulged keel”.
The P-47C was the first variant to be used in action, being introduced in Europe during 1943. In total 565 were built.
The P-47D was by far the most numerous of all Thunderbolts, and saw also the most changes during the course of its production.
Initial production batches were externally similar to the P-47C, but ongoing developments included the addition and refinement of four additional cowl flaps. Standardisation of the “bulged keel”, introduction of wing Pylons, and wider chord propeller blades.
The P-47D-25 saw a more change to the profile with the first “bubbletop” canopy installed behind a redesigned windscreen on a cut-down rear fuselage. Fuel capacity increased, ailerons were redesigned.
All in all more than 12000 P-47D’s were produced. The P-47M was a high performance P-47 and was the first Thunderbolt to be fitted with the Pratt&Whitney R-2800-57 C series engine.
The P-47N was a long-range escort variant that also used the Pratt&Whitney R-2800-57 C series engine.
It featured an increased wingspan with clipped wingtips, relocated landing gear and the large dorsal fillet.
My imitated prototype;
As prototype I chosed the P-47 Snafu.
June 2011, I was in England to fly with my B-17 Flying Fortress and my P-61 Black Widow on Tibenham Airfield (Station 124 in WW2),
this for the Salute to the 445th BG. (The famous actor James Jimmy Stewart, was there also stationed as a commander and pilot of a B-24).
During that time I also visited the Duxford Museum, and there I saw the restoration of the P-47 "Snafu" almost finished, and I made a lot of Photos for the case that! (Indeed, 10 years later I started the project P-47 Thunderbolt “Snafu”).
The original Snafu (1943-1944): (pictures 00A-00D)
274742 (MSN 3093).Is a P-47D-RE Thunderbolt. This was The original “Snafu”! (Built by Republic)
274742, WZ-D, "War Eagle"
Later on; WZ-D "Snafu" (Abbreviation for: Situation Normal And Fucked Up). Crash landed 15 Dec. 1944 at Duxford.
42-74742 Delivered to USAAF. 1943.
Assigned to 84th FS, 78th FG, 8th AF, Duxford UK, Station 357. 1944. War Eagle “Snafu”.
Pilot: Severin B. Calderon.
Belly Landing 15 Dec. 1944 at Duxford (station 357). Pilot; Earl L. Steir. The imitated Snafu (1943- up today, and is not the same plane as the original "Snafu"):(pict.00E-00L)
225068 (MSN 21962). Is original a P-47G-CU Thunderbolt. (Built by Curtiss)
1943-1945; -Delivered to USAAF Sept.1943, Serial Nr. 42-25068.
-Transferred to the 3rd Air Force at Tallahassa Florida for a training role. Struck of Inventory June 1945.
1946-1952; To Aero Industries Technical Institute, Oakland Airport, California USA, as a ground instructional airframe.
1952; To Jack P. Hardwick/ Hardwick Aircraft Supply, El Monte, California.
1953; Rented to Allied Artists for ground Scenes in the film "Fighter Attack".
1955-1975; Used by Flying Tiger Line as ground engine test rig at Oakland CA. Than Parked up in El Monte California.
1975-1981; -To Eagle Aviation, Tulsa, Oklahoma USA. Restoration commenced; Hurley Boehler/ Sirrus Aviation.
-To Ray Stutsman, Elkhart in Indiana USA, 7 Dec.1979
- Registered N42354 May 1981.
1982-1987; -April 1982 Restoration Completed. Reregistered N47DG Feb.1982, Flown as 28476, YJ-X "Little Demon".
-Grand Champion Warbird, Oshkosh July 1982, by Ray Stutsman.
1987-1999; To Robert L. Waltrip/ Lone Star Flight Museum, Houston, Texas USA. Later Galveston Texas USA, May 1987.
1999-2003; To David Arnold/Flying A Services, UK 1999. Registration cancelled 14 April 2000. Withdrawn from Use, July 2000.
2003-2005; Stored in UK (reported stored in container at North Weald 2003, and at Greenham Common 2005).
2005-2008; -To Tony Raftis, Melbourne, Victoria Australia 2005. Reported shipped to Australia but resold on arrival.
-To The Fighter Collection, Duxford UK 2005;
-Registered as G-CDVX to Patina Ltd/ The Fighter Collection, Duxford UK, 20 Feb. 2006.
-Unpacked from crate in hangar at Duxford UK, 4 June 2006.
-Re-packed in container at Duxford UK Sept. 2006 for shipping to Chino, California, for restoration to fly.
-Wings at Wangaratta, Victoria Australia, 2007.
-Fuselage arrived at Duxford UK 9 July 2008, after shipping from Chino.
2009-2012; Final restoration and assembly commenced at Duxford UK 2009.
2012; First flight 21 April 2012 as 225068/WZ-D "Snafu". Color Scheme; Olive Drab (the early browny one) & Neutral Grey.
2013-2014; - Dismantled at Duxford Aug. 2013 for shipping to USA. Comanche Warbirds Inc, Houston, Texas.
-Registration cancelled 24 Jan. 2014 on export to USA;
2014; Registered N47FG to Comanche Warbirds, Houston, Texas, 28 Jan. 2014.
42-25068 Delivered to USAAF,3rd Air Force Florida for a Training Role in sept.1943. Struck of Inventory in June 1945.
Warbird; “Little Demon”. 42-8476.Flown as 28476,YJ-X.(Ray Stutsman, USA.1979-1982).
Warbird; “Little Demon”. 42-8476. YJ-X.(Flying A Services UK. The Fighter Collection. Duxford,GB. 1999-2008).
Warbird; “Snafu”. 42-25068.Flown as 225068, WZ-D. (The Fighter Collection. Duxford, GB. 2009-2012).
Warbird; “Snafu”. 42-25068.Flown as 225068, WZ-D. (Comanche Warbirds Inc. Houston Texas, USA. 2014- up today).
Documentation:
I have a lot of books about the P-47 Thunderbolt, most of them in PDF (66x).
On the internet I found also a lot of info and pictures of P-47 Snafu.
Besides, I had a lot of Photos of the Restoration, when I had visited Duxford in June 2011.
THE MODEL.
Plan, Electric Retracts & Engine (Starting in november 2020);
-Drawing: (picture 001-003).
Again the plan was drawn by myself, completely worked out, 99,90 % scale and nothing was left to a mischance. (35mm slides were made from the more side-views and projected until the right scale, traced on transparent paper and afterwards the construction was drawn in, sections were drawn and also all the formers, etc.!
Everything, down to the last detail, was well considered and put on paper (old-fashioned isn’t it!), and the construction was kept as light as possible.
Only the ribs were drawn with the computer, because the wing is tapered, and it has an airfoil changing towards the tip!
The plan was ready in January 2021, after 200 hours work!
-Wing & Stabilizer joiners: (pict. 004).
-Wingjoiners: dural tubes ø 20mm at the front, and ø 30mm in the middle.
- Stabilizer joiners; carbon tubes ø 8mm at the front, and ø 10mm at the rear. -The Electric Retracts; (picture 005-006).
This time I did not construct the maingear myself, but bought them; The Electron ER-40. The Oleo Struts are the Robart 673R+L.
Wheels; Engel Light-Wheels 125/36mm.
The tailgear I constructed myself with Robart compenents + self made parts & an electric actuator from Electron.
-Engine; (pict. 046-047).
I am very Satisfied with all my Laser 4-stroke engines:
On my Scale models;
- 4x Laser 70 (11,5cc) in my B-17 Flying Fortress (Scale 1/8th, span 4m., weight 19,3 kg).
- 1x Laser 90 (15cc) a very old type, in my Spitfire (Scale 1/8th, span 1,40m., weight 3 kg).
- 2x Laser 240-V twin (40cc) in my P-61 Black Widow (scale 1/6,6th, span 3,10m, weight 18,5 kg).
- 2x Laser 240-V twin (40cc) in my A-26B Invader (scale 1/5,7th, span 3,60m, weight 21,5 kg). Further I have 2x Laser 70’s (11,5cc) on my twin-engined Harmony,
and unused; 1x Laser 240-V old-type (40cc), and 2x Laser’s 150 old-type(25cc).
So again I chose a Laser Engine: The 300-V twin (50cc) four-stroke. THE BUILDING: Fuselage & Tailplane (see pictures 007 till 036)
Fuselage. (pict. 007-019)
In Nov.. 2021 I started to saw the Fuselage formers.
Some formers are out of 3mm Birchply (200 gr/0,1m²), some of 3mm Liteply (140gr//0,1m²) and some of 3mm Balsaply (90gr//0,1m²). In Dec. 2021 I started to build the fuselage.
Some front Formers together with the strengtheners were glued together. The Guidetubes for the Wingjoiners were aligned with the help of the Fuselage-ribs and the Wing-Rootribs and than glued to the Stengtheners and Formers.
The pair of rootribs for the fuselage I did not glue on them yet (later, as the winghalves open construction is ready, so that I can still pinpoint everything).
Then the rest of the Formers were positioned, and the Retractable Tailwheel mounted.
The Guidetubes for the horizontal Stabilizers were aligned with the help of the Tailplane-ribs, but also not glued to the formers yet! (Later together with the paxolin (Pertinax) supports for the elevator control linkages).
At last alle the stringers were glued to the formers (They are all at the same place as at the original panellines).
Now I had to make some provisions first; Guidetubes for the closed loop Linkages (4 tubes for both Elevator, 2 for Rudder, 2 for Tailwheel steering), because the Servos for these are almost in the front of the fuselage.
The Fuselage has total 6 Servos; 2x Elevator, 1x Rudder, 1x Tailwheel steering, 1x Throttle, 1x Landinglight-switch on a servo.
Further, I glued in the the Servo-floors, Reciever-floor and Batteries-floor (Later on, above this floor came the Tankfloor).
I made provisions for the Intercooler doors, also tubes slantingly through the Engine bulkhead, 1x for extra cowl-cooling (Exhaust) and 2 tubes for the Laser Exhaust gasses (coming out on the place of the original Oil cooling shutters).
Than the airframe was planked as far as possible. Wing and tailplane fillets are built in on the fuselage, and the flowing lines for them were achieved in the relevant formers.
When the glue for planking was dry (mainly clear PUR. construction glue), the fuselage-halve was turned upright, supported by foam blocks. Now the upper section could be build on, but first before this I had to built the horizontal stabilizers. The Horizontal Stabilizer. (see pict. 019-026)
As I wrote before, I had to built the Stabilizer first (NACA 0012), before I could glue on the Tailplane ribs and Stabilizer joinerguides to the tailplane.
First I made raised supports (picture 0020) out of 12mm cheap ply to built on the stabilizer-halves. On these, with sellotape between it, the lower spars were pinned, then the ribs could be glued on (rootrib with an right angle to the building board, the other ones with an right angle to the mainspar support!). The provisions for the Joiners for Stabilizer-Tailplane were made (carbon tubes; the front ones Ø 8mm, the rear ones Ø 10mm), so also the square Brass Tube for the Elevator Linkage (picture 0021).
The Robart Pin hinges with a 1,5mm pianowire through a plastic tube were adjusted.
Then the upper spars and also the leading edge were glued on.
Now the open construction was ready, and the stabilizer joiners + the square brass tube could be cut through in the middle (picture 0022).
The open construction could be taken of the supports now, for adjusting and pinpointing to the Tailplane.
The inner elevator closed loop linkage on each side for the removable stabilizers were built in (the two servos are not at the rearend,
but in the front, this in connection with the extra weight at a wrong place), the square brasss tube on each elevator, sliding into a
twisting square brass tube on each side too, with each a control horn and supported in Paxolin (Pertinax) bearers (pict. 023-024).
As everything was adjusted and pinpointed I could glue the Tailplane ribs and stabilizer joinertubes on and in the Tailplane, with the
Stabilizer-halves slided on. (Pict. 025) (The stabilizer-halves will be secured later on with metal-screws, through woodblocks glued
on top of the guidetubes, in to the joinertubes. In the joinertubes are glued short pieces of birch dowels ).
Now the stabilizers could be planked. First the under-surface and than replaced on the supports and weighted down, this ensures the
retention of a true straight wing. The same procedure was followed for the upper-surface (pict. 026), and later on the rudders could be separated from the stabilizer-halves and became a convex leading edge, this in a cavity of 0,6mm ply strips. (pict. 032).
Fin, Rudder & the Razor Back. (see pict. 027-036)
The Fin-construction and the Rudder are build on in one piece too.
Now the Fin and the rudder (NACA 0009), in one piece with it, could be constructed, hinges are 6mm ply (and 1,5mm pianowire through a plastic tube), after planking the rudder could be separated too from the fin and became also a convex leading edge, this in a cavity of 0,6mm ply strips too.
Now the Razor back could be constructed.
The servos for the Rudder, Elevators and Tailwheel are in the front of the Fuselage and they have all a closed loop linkage (pict 036)
Cockpit compartment (see pics. 037 - 045)
The whole cockpit hood is removable (as with all my large models, and everything is very accessible).
The hood has an extended floor, which fits into the fuselage, just above the servos. This for a scale cockpit interior and the Pilot.
I made the the moulding for the clear cockpit from Liteply and balsa parts.
Than the project was stopped because of the coming new flying season and I had to prepare my models for it, because I bought a new transmitter, a Graupner MC-28 Hott (my Graupner MC-24 with 2,4Ghz Hott was now over 25 years old !), and had to programm these models into the the new Transmitter.
Sept-Oct. 2022.
I continued the P-47 project and started with finishing the moulding for the clear cockpit by covering the moulding witth 25gr. glascloth and polyester. Also the Instrument panel for the Pilot was made, than the all the details for the cockpit-compartment, placed the pilot and on his seat and glued on the clear vacuum formed cockpit. On these clear cockpit I glued aluminium tape (self adhesive) for imitating the cockpitframe.
Engine. (see pics. 046 - 047)
The engine I shall use, is a Laser 300V-Twin 4-stroke, for wich I made silencer extensions straight into the exhaust vents of the prototype plane (oil cooler shutters).
Wing. (see pics. 048- 075).
Oct. 2022, after a week sawing, the parts for the Left & Right wing were ready (pic. 049-050).
The ribs are out of Balsa and Lite-ply. Some ribparts are out of paxolin (pertinax)
The wings have an own mix of NACA 2215 & Sikorsky S-3/15% for the rooth rib to the beginning of the ailerons, and from there progressing to NACA 2208 profile at the tip. A wash-out has been built in on the raised supports.
Wings I always build on raised supports (strips of 12mm cheap plywood, see pic. 048).The wash-out and the dihedral are already build in these supports (matter of drawing and calculating !). Because of the large wing chord I will use 3 supports: under the main spar, front spar, and rib-ends.
On these, with sellotape between it, the lower spars were pinned, then the ribs 1 till 4 for the wing could be glued on. The Ribs nr. 1 are at a right angle to the building board ! (The ribs 2 till 14 are at a right angle on the Supports! ).
Then the guide tubes for the wingjoiners to the fuselage were adjusted-pinpointed (parallel and 0°, see pic. 051) but not glued yet !!
The wingjoiners are dural tubes ø 30mm at the main spar, and ø 20mm at the front. (later on secured with parkers straight through woodblocks in the wing and woodpieces in the tubes).
Now all the remaining ribs, 5 till 14 were glued on the lower spars, also the 2mm ply-strips near the ribends (pic. 052) for screwing on the Flaps- & Ailleron hinges. Than the upper spars, leading and other edges were glued on.
The guide- tubes for the wing-joiners were not glued yet, so I slided them again into the wings,. than I slided the joiners into the fuselage, slided than the Left wing on to the tubes, than the Right wing, and checked if the Incedence of both wings were the same. The Tailplane was connected to the fuselage and I checked and adjusted the Right-wing over the stabilizers, also the Left Innerwing (Photo 98), and than I glued the wingjoiners to the wing ribs, the wings remained connected to the fuselage. (The wing-halves will be secured later on with parkers straight through woodblocks glued on top of the joinertubes into woodpieces glued in the tubes. Pict. 057 ).
Dec. 2022 -Jan. 2023.
Many provisions were made to the wings. Extra balsa stringers (5x2mmm) for the panellines, provisions for the wing-guns, droptanks, retractable landing-light. Hinges for the Flaps and hinges for Aillerons were made and installed. The Flaps were provided with special flap hinges, recessed into the undersurface, there is a gap between wing undersurface and flaps when these are lowered, giving so more lift and less drag! The aillerons are provided with special hinges for the typical P-47 Frise-aillerons also recessed into the undersurface.
The main-gear with the oleo-struts and wheels were installed, provisions for the main gear wells were made. Servos for the Aillerons, Flaps, landing light (only left-wing) and main gear doors were installed. The ailerons and flaps are controlled with M2,5 rods & kwiklinks.
Now the winghalves could be planked. (see pict. 064-078)
The wing panel sheeting is commenced with the wing-underside and the wing was replaced on the supports and weighted down, this also ensured the retention of a true straight wing. The same procedure for the wing-upperside. The separate planked Frise-ailerons and Flaps were cut out and became a convex leading edge, this in a cavity of 0,8mm ply strips (only upperside. see picture 72).
Now I had to provide the wing-fillets on the fuselage and fore that I needed the both finished wings, left and right, to adjust the fuselage-ribs to the wings. Than I planked the wing-fillets. (See picture 069-070).
At last the alu. coverings for the main Gear-Oleostruts were made and attached with clamps & alu. distance tubes, the alu. innerdoors were made, attached and controlled with a mini-servo. (See picture 073-075).
Now everything was constructed and details could be made or placed.
Details; (see pics. 076-082)
Feb. 2023-March 2023.
Now the last details could be made, such as; Guns, Pitot tube, Position lamps, Intercooler Exhaust-doors, Turbosupercharger Exhaust-doors, Tailwheel-doors, Antenne, Oilcooler-doors, Exhaust waste gates &vents.
Finishing the Model; (see pics. 083- 093)
March -April -Mai 2023.
Cowling & Radial Dummy: (see pict. 086-091)
For the cowling I had made a moulding of ply and balsa filling blocks. The Cowling I formed from GRP with help of a big balloon (blown up) and pushed over the mouldings. For the Radial Dummy engine I made a moulding for vacuum forming.
Now I could start finishing the model;
After a final sanding, everything was covered with lightweight, Japan tissue (paper) 12 gram per square meter, and one coat of clear shrinking dope, and carefully light sanded. Then scale panels and so on were scratched- in with a very small triangular keyfile, than one more coat of clear shrinking dope (now 10% thinned) and light sanded, than the flush rivets were applied with selfmade sjablones & tools (see pict. 085), and at last a third coat clear shrinking dope (now 20% thinner).
Mai-June 2023.
Spraying & Handpainting; (see pict. 092-093)
So, now I could spray everything with a washprimer and after hardening, I sanded it with waterproof sandpaper 400. Then I sprayed the model in the basic colors; underside in Neutral Grey Shade 43/ FS 36173, upperside Olive Drab Shade 41 (see pic. 086).
After this I had to spray some areas with Insigna White and after that some Black stripes (Invasion Stripes),and on the cowl Black squares over the White for the checkerboard pattern.
6 June 2023.
After handpainting the Nose-Art, all the spraying and painting was ready, than the radial dummy engine was formed and glued into the cowl.
RADIO INSTALLATION;
At last my Graupner MC-28(Hott 2,4 GHZ) radio equipment was installed and I needed 11 channels. Total 15 servos!
1x Graupner Hott GR24 receiver + 1x 12 channel Emcotec DPSI powerbox ( Dual Power Servo interface because I always fly my large scale models at least with 2 reciever batteries), 1 electronic switch, 4x LiFe batteries 2500 mAh (2 batteries for the Emcotec powerbox + 1 battery for the retracts +1 battery for the landinglight ). Fuselage servos:
Front; 1x Throttle + 2x Elevator + 1x Rudder + 1x landinglight servo-switch + 1x tailwheel- linkage control =Total 6 servos.
Rear; 1x Tailwheel-actuator for Retracting.Wingservos:
2x Flaps+ 2x Aillerons + 2x gear-well doors + 2x Droptanks/Bombs + retractable landinglight = 9 servos. Total: 15 servos!
Mixers: Total there are 5 mixers used! From simple to complicated, but not no problem for the Graupner MC 28!
Additonal settings includes: Aileron-diff. ,exponential, curve-mixers and of course Fail -Save, etc.! See also chapter Technical Solutions for my Large Scale Models. 2 July 2023;
The model is ready (Photos 094-100)
Also the extension servoleads have been made.
I have weighted the model on C.G and needed only 500gram lead in the nose, the total weight is 11,5kg (25 lbs).
Ready to make the maidenflight, only the engine must be running in, than built on again.
MAIDENFLIGHT; (photos 101-116 ) Wednesday 16 august 2023, 12.00u; The P -47 had her Maidenflight at my homebase (modelairfield MVV Delta Oss, NL).Everything went very well, the engine, Laser 300-V Twin (50cm3) was running fantastic, a little bit rich of course (new !), the P-47 speeded up rapidly in a straight way, a little bit up-stick and she was airbourn. Retracts up, and the only trim was some tickles down!
The throttle some back and I flew some rounds, than I gathered more height, throttle full back, and the plane started a perfect glide, again more height and the same, now with full flaps, and another glide, the model flew very slow now ( C.G. on 28%).
Than full throttle to test the model on the limit. No problems she flies and response wonderfull!
At last I flew a landing-circuit, throttle half back, gear down, 1/4 flap, and on final 1/2 flap and throttle on idle, and a little bit up-stick. Slowly the P-47 approached to the runway, and had a very nice touch down!!
I was very satisfied with the Maiden of my P-47 Thunderbolt Razorback, scratch built from my own plan!! | 00A | 00B | 00C |
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