The installation of instruments, hydraulic, water injection, and oil tanks was a large part of the restoration work this month. Progress on the wing assembly was also made as the Thunderbolt gets closer and closer to completion.
Aaron has been busy continuing systems and instrument installation in the P-47 cockpit.
Installed in Allied aircraft as part of the Identification, Friend or Foe (IFF) program during World War II, this system would send a signal for 14 seconds of every minute over the pilot’s radio to the ground station. The pilot could not speak while the unit was broadcasting. Designed to fit in a standard gauge slot, it has two switches (contactor in or out, and clock stop or run), has one small knob (wind), and has a clock face that indicates the time the unit is broadcasting. 1
1 National Museum of the Air Force, https://www.nationalmuseum.af.mil/, accessed 6/18/2020
Hydraulic system tanks, oil tanks, and the initial fitting of the water injection tank made up much of the fuselage work this month.
The P-47D-23RE had a 15 gallon tank to hold the water/methanol for the water injection system. Water/Alcohol injection cools the flame temperature and controls flame propagation, thus preventing detonation which can break piston rods and pistons. These systems allowed for higher manifold pressure, and added 300 Horsepower at the push of a button on the throttle quadrant.2 The tank allowed about 5 minutes of power boost. Latter versions of the P-47 (P-47D-25RE and subsequent) doubled the capacity of the water tank.
2 Graham White, Allied Aircraft Piston Engine of WWII,Warrendale, PA, Society of Automotive Engineers, 1995, p244
The P-47 was a versatile fighter/fighter-bomber. Bombs, rockets, and of course .50 caliber machine guns, were all part of the possible armament loads. Many different drop tanks were used in the quest to extend the range.
The most common tanks and ordnance are shown below. Normally, the P-47 could carry six or eight .50 cal. machine guns, and either 10 rockets or 2,500 lbs. of bombs, or any combination that totalled 2,500 lbs.
Here is an interesting Republic Aviation document that originally specified 3 .50 caliber Brownings in each wing with a four gun wing as an alternate load. Bomb shackles are also specified on the second page. The vast majority of combat P-47s carried four guns in each wing.
The eight .50 caliber Browning M-2s are familiar, so we will examine the more common drop tank and bomb and rocket loads.
A variety of different drop tanks were fitted to the Thunderbolt during its career. The earliest tanks were the conformal 200 gallon ferry tanks, and the lozenge-shaped flat 200 gallon belly tank. The P-47 also used British-designed 108 gallon and 200 gallon tanks made of plastic-impregnated paper. These “paper” tanks were relatively inexpensive but couldn’t store fuel for long periods of time. With the increased fuel capacity gained with drop tanks, the P-47 was able to perform missions deep into enemy territory.
Later, teardrop-shaped 75 US gallon and 150 US gallon metal wing drop tanks were adopted. Another drop tank that was used was the 165 gallon teardrop tank first intended for the P-38.
British 5 inch rockets were also used.
I am interested in the 108 gallon paper tanks fitted to the P47 Thunderbolts. My Grandfather Alexander Clark was an engineer at Bowater-Lloyds paper factory at Sittingbourne, Kent (UK), which was the largest papermill inthe world at the time of WW2. He had a part in developing and manufacturing the 108 gallon tank. He left me a tenth scale model of the tank and a photograph of a pilot kneeling next to the plane. The pilot was Captain W Motzenbecker, who led a flight of four P47s on 19 December 1944 and destroyed a number of German tanks. The photo is signed on the back and appears to be identical to the one of the kneeling pilot on the Aircorps Aviation site.