View Full Version : Another P47 Question

09-20-2007, 03:42 PM
I'ts been a long time and most of my flight time has been in Corsairs and Hellcats for the past 2 years.

Here is my question, is the supercharger not controllable in the P47? its modeled right, we just cant change the settings making it sort-of auto?

09-20-2007, 03:42 PM
I'ts been a long time and most of my flight time has been in Corsairs and Hellcats for the past 2 years.

Here is my question, is the supercharger not controllable in the P47? its modeled right, we just cant change the settings making it sort-of auto?

09-20-2007, 03:49 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Hookecho:
I'ts been a long time and most of my flight time has been in Corsairs and Hellcats for the past 2 years.

Here is my question, is the supercharger not controllable in the P47? its modeled right, we just cant change the settings making it sort-of auto? </div></BLOCKQUOTE>


The P-47 supercharger is not controllable. It is a type of supercharger commonly referred to as a "Turbocharger"

09-20-2007, 04:03 PM
you mean not controllable in the sim right? It is modeled correctly in that the sim controls the turbo RPM's with reguards to throttle and manifold pressure?

I believe General Electric called it a turbosupercharger, and controlled it with a electronic rheostat. I'm pretty sure there is a lever on the throttle quad for its operation and that the british pilots didnt like it because it was overly complicated.

from something I found on the "internets"

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">A.F.D.U., RAF Station, Duxford
Report No. 66
Tactical Trials - P47C Aircraft

1. In accordance with instructions from Air Ministry (D.A.T.), reference C.S.16286 dated 2nd January 1943, tactical trials of the P-47C "Thunderbolt" have now been carried out at this Unit. Aircraft Nos. 16198 (Mk.2 R.E.), 16319 and 16324 (Mk.5 R.E.) were loaned by the VIII Fighter Command of the U.S.A.A.F., together with flying and ground personnel for the duration of the trial. This report has been produced with the collaboration of their Headquarters Staff.

I have skipped No.s 2-4

5. The cockpit is enclosed by a sliding hood with jettison device, and is very roomy and comfortable. The positioning of instruments and controls is reasonably good but the cockpit is considered complicated in a British pilot's eyes, as in addition to the normal controls, he is provided with an extra lever on the throttle quadrant to operate the supercharger, and electric switches to regulate the shutters for intercooler and oil cooler. It must, however, be pointed out that both these shutters can be left in the neutral postion below the rated altitude except in an emergency. The supercharger lever can be linked to the throttle so that both are operated together and in this condition, although rather heavy for a fighter pilot's controls, gives smooth operation. An alternative method is to use the throttle only until a height has been attained at which it has reached the far end of the gate and then to bring up the supercharger lever to maintain the required boost and to use that lever only as the engine control at altitude. The drawback to the last method is that the supercharger control by itself becomes far too sensitive as altitude is gained, very small movements on the quadrant resulting in large increases or decreases of manifold pressure. If throttle back suddenly to prevent over-shooting at target at altitudes, the supercharger appeared to take longer than an engine driven driven one before it was delivering full power again when opened up. The maximum allowable r.p.m. for the turbo-suprecharger is 18,250 and a revolution counter is included on the dashboard. This speed will not be exceeded below the rated altitude (27,000 feet) but there is a risk of it happening at greater altitudes if the supercharger control is pushed fully forward, as no governor is fitted. There are a number of occasions on record when the maximum revs. have been exceeded without failure, and it is stated that the limit set is well within the safety range. </div></BLOCKQUOTE>

09-20-2007, 04:13 PM
I'm not going to quibble about GE's name for it

09-20-2007, 04:17 PM
sorry didnt want to quibble and I was trying to find a RAF report about the "turbo" and add it to my post...anyway thanks for the reply

09-20-2007, 04:44 PM
Turbo in P-47 is automatic; there is no way to control it manually (in the game).

09-20-2007, 06:43 PM
In real life the speed of the turbosupercharger was manually controlled by the lever on the quadrant that is marked 'B.' As the lever was moved forward, more engine exhaust pressure was diverted to power the turbine's bucket wheel which in turn increased the density of the air pushed into the engine's carbureator. The turbo lever was moved in careful coordination with the throttle lever to maintain specific power settings at different altitudes. As I recall, pilots were warned to never advance the turbo lever beyond the throttle, and to always back off the turbo before reducing the throttle. Also, in at least some models of Thunderbolts the turbo lever and throttle lever could be physically linked together during operations as a convenience. Final variants of the Thunderbolt, the P-47N series, introduced an automatic turbo control but that wasn't until the very end of the war.

Within the game the turbo lever never moves. I believe that a coordinated relationship between the turbo and throttle is assumed and therefore the lever is simply not animated. I know there is a turbo RPM guage on the panel that indicates how fast the turbine is spinning. Regardless, the turbosupercharger 'stages' can't be manually changed regardless of what the Aircraft Guide.pdf says for the Thunderbolt.

Technical Order No. 01-65BC-1
Pilot's Flight Operating Instructions
P-47B,-C,-D and -G Airplanes
January 20, 1943


(1) THROTTLE.--Additional supercharging for this engine is furnished by an exhaust-driven turbine supercharger. The engine is controlled by the conventional throttle, propeller and mixture controls. The supercharger is controlled by a control located outboard of the throttle. On P-47C and subsequent models, the throttle, supercharger control, and propeller control are made so that they can be pushed forward by use of the throttle alone. When properly adjusted, this position should give about 52 inches HG and 2700 rpm at altitudes up to 25,000 feet. It may be necessary to push past the stop to obtain full power above 25,000 feet. When the controls are connected, the supercharger will come back as the throttle is ******ed, but the propeller control will remain at the farthest advanced position. Rpm must be reduced by pulling the propeller control back.


a. The supercharger control should be set so that with full throttle, and supercharger control "FULL ON," 52 inches HG at 2700 rpm is obtained for take-off. When operating at high power above 7000 feet, the throttle should be wide open and should be left there. Adjustments of power should then be made by the supercharger control. The supercharger control should always be moved slowly, so that manifold pressure will follow and overboost will be avoided.

On airplanes equipped with interconnected engine controls, power may be adjusted by operating the throttle only, provided the supercharger and propeller levers are engaged with the throttle.

NEVER shut off throttle completely with the supercharger "ON." Power at altitudes above 27,000 feet is limited by the rpm of the turbine only. Overspeeding of the turbine must be avoided, except in extreme emergencies.

09-20-2007, 06:50 PM
Thanks....thats what I was looking for, we are unable to adjust the "turbo" and the sim does it for us in realation to throttle and manifold pressure.

09-20-2007, 07:23 PM
AN 01-65BC-1A
Pilot's Flight Operating Instructions
For Army Models
P-47D-25,-26,-27,-28,-30 and -35 Airplanes
British Model Thunderbolt
25 January 1945


a. A General Electric type-"C" series turbosupercharger is installed in the lower section of the fuselage aft of the cockpit. Engine exhaust gases are directed to the turbine wheel of the supercharger through exhaust pipes on each side of the fuselage. Fresh air is collected in the scoop beneath the engine and conducted to teh compression section of the supercharger. Heat generated during compression is dissipated by passing the supercharged air through an intercooler which is cooled by a portion of fresh air blast. The quantity of fresh air flowing through the intercooler is controlled by exit duct doors which are electrically operated and activated by a toggle switch in the cockpit left wall. an indicator denotes the position of the doors. All models include a built-in air filter which may be bypassed by using the control handled located to the left and aft of the pilot's seat.
b. The quantity of supercharged air directed to the carburetor is determined by the setting of the booster lever on the engine control quadrant. This lever sets an engine-oil operated regulator which is balanced against exhaust pressure. When engine exhaust pressure drops, the supercharger regulator closes a waste gate in each exhaust pipe, which permits more of the engine exhaust gases to be directed against the turbine wheel of the supercharger, thus maintaining boost.


a. Operate engine within limitations outlined in Specific Engine Flight Chart in Section III.
b. To reduce power, first ****** interconnected boost and throttle levers; set rpm with propeller control, and then adjust power lever for desired manifold pressure.
c. To increas power, push throttle forward; a latch on the control lever insures that the propeller lever will move forward also.
d. Above critical altitude it will be necessary to disconnect controls and adjust boost and throttle independendtly to avoid overspeeding of the turbosupercharger.

Never exceed the red limit line marked on the turbo tachometer.

e. Most stable high-altitude operation is obtained when power adjustment is made by boost control alone. However, caution must be observed to prevent two conditions as follows:
(1) TURBO COLLAPSE.--When power is reduced by ******ing the throttle or engine speed, leaving the boost well forward, a consequent reduction in exhaust back pressure occurs. When this condition approaches the point where there is insufficient back pressure to maintain required boost, a further reduction in power and back pressure results, finally causing complete collapse. Recover from collapse is achieved by nosing down and advanicng throttle and engine rpm to encrease exhaust pressure which again sets the supercharging system in action. Recovery from complete collapse at high altitudes may take as long as 30 seconds.
(2) PULSATION.--At another range of the throttle with the boost lever well forward, when power is reduced by throttle or propeller control, it is possible to "dam" the turbo. In this condition, there is sufficient back pressure to operate this supercharger, but the engine is not absorbing its output, which results in "damming" the pressurized air and causes pulsating pressures in the ducts. Since the fuel pump is balanced against carburetor air, turbo pulsation causes fluctuation in fuel pressure and, if allowed to continue, will cause sufficient fuel-air ratio disruption to result in engine surging. Pulsation is detected by fluctuating fuel pressure and may be corrected by either ******ing the boost lever or advancing throttle or engine speed.

09-20-2007, 07:53 PM
Pilot Training Manual For The Thunderbolt P-47
AAF Manual No. 50-5 (March 1945?)
Redesignated as AAF Manual No. 51-127-3 (10 Sep 45)

The P-47 has two superchargers: a geared device which is an integral part of the engine, and a turbo-supercharger, installed just forward of the tail section.
The P-47's fame as a high-altitude fighter stems from the turbo. It gives the plane maximum performance at 27,000 feet. On the latest series maximum performance is obtained at 30,000 feet.
The supercharger's operation is quite simple. Air is compressed by an impeller which is spun by exhaust gases blowing against a bucket wheel attached to the same shaft. The super-charged air is then forced into the intake via the intercoolers.
An indicator showing the position of the intercooler shutters (panel doors on each side of the fuselage) is on the left of the cockpit. It is marked CLOSED, NEUTRAL, and OPEN.
The shutters, electrically operated, are controlled by a toggle switch on the main switch panel. On the D-25 and subsequent series, the toggle is beside the indicator.
Normally you fly with the intercooler doors OPEN, but in cold weather you may need the doors in NEUTRAL or CLOSED to give correct carburetor air temperature. Doors must be in NEUTRAL for any speed above 350 mph.
A lever on the throttle quadrant controls the turbo. The lever regulates waste gates, which either direct exhaust gases against the bucket wheel, or permit the gases to escape.
When the P-47 is serviced with grade 100 fuel, the turbo control can be inter-connected with the throttle by means of a link.
Disconnect the controls for starting, to enable you to crack the throttle while leaving the turbo off, and at high altitudes, when with the throttle full forward, it's necessary to pull back on the turbo to avoid overspeeding.
However, when grade 91 fuel is used in training, disconnect the link below 7000 feet. The precaution is in force to lessen the danger of exceeding allowable manifold pressures.
Above 7000 feet, the link may be connected to assist you in remaining in formation. Disconnect it when you descend.
When the link is not connected, use the turbo control as a second throttle.
In other words, after the throttle is full forward, use the turbo to maintain the desired manifold pressure. The turbo is needed at about 12,000 feet.
Always pull the supercharger back first. Under no circumstances, let the throttle get back of the supercharger lever, or the turbo will be damaged by building up pressures that have no means of escape.
Your plane, depending on the series, has a turbo tachometer or warning light on the panel.
The turbo tachometer is red-lined at 18,250 rpm. Do not exceed this limitation.
The turbo warning light goes on the instant you start the engine. It glows steadily unless you use the turbo. In this case, the light starts to flicker until until a speed of 18,250 rpm is reached. Then it glows steadily again. When this happens, reduce the rpm. The turbo is over-speeding.
When using the turbo, the rule is to keep the light flickering.
The D-25, and later series, have both a turbo tachometer and warning light. The light goes on at 22,000 rpm to indicate overspeeding when war emergency power is being used.

09-20-2007, 08:48 PM
This selection from the P-47N Training Manual isn't completely relevant to the game, but perhaps of interest to you:

AAF Manual 51-127-4
Pilot Training Manual For The Thunderbolt P-47N
Hq. Army Air Forces
Washington 25, D.C. 1 Sep 45

The P-47N has two superchargers; an impeller attached directly to the engine, and a turbo-supercharger which gives the plane its superb high altitude performance. The turbine, which is spun by exhaust gases, sends supercharged or pressurized air to the carburetor where it is fed through the impeller into the intake manifold. The turbine speed is controlled by electrically-operated waste gates which govern the amount of exhaust gas pressure reaching the bucket wheel. Excess exhaust is directed over-board.
In making the trip to the carburetor, the supercharged air, heated by compression, passes through the intercoolers where it is cooled to proper temperature. The amount of cooling received is regulated by intercooler doors. The temperature is shown on the carburetor-air temperature gage. The intercooler doors are controlled either automatically or manually. Maximum allowable turbo rpm is 22,000. When not in use the turbine idles at around 2000 rpm. The speed of the turbine varies between these two extremes, depending on altitude and power required.
Early N's contain a turbo tachometer and an overspeed warning light. The instruments were subsequently removed, inasmuch as turbo overspeed is prevented by the regulator.
An ON-OFF switch on the main switch panel enables you to cut off the current to the waste gear regulator and thus stop the gates in the last position. Normally the switch is left in the ON position, protected by a guard. If it should be necessary to turn the switch OFF on the ground, pull the boost control all the way back first. This is to make sure you don't leave your waste gates fixed in any but the full open position. Otherwise you might get some turbo pressure you don't want.
During a climb or dive, the regulator will maintain a constant manifold pressure at only one power setting--approximately 39" Hg. This pressure will be held constant from sea level to the critical altitude for that power. At any higher lower setting you must make minor power adjustments to keep your manifold pressure steady.
When you climb with full military power (54" Hg, 2800 rpm), the regulator allows an increase of 1" Hg for each 6000 feet of altitude. Keep pulling back slightly on the power to avoid getting into the water injection range.
The regulator limits your power output to 72" Hg (maximum for the engine) only when your plane is in a climbing altitude. If you pick up speed and greater ram by leveling off or diving, pull back on the power to keep the manifold pressure from going overboard.
You obtain the most stable and economical high-altitude flight by making power adjustments with your boost alone, after your throttle is full forward. When flying in formation, however, you may find it profitable to vary this technique by leaving yourself a small margin of throttle. Use this bit of throttle range to stay in position. The plane responds more quickly to throttle than to boost.

The boost control has a spring-loaded latch which provides for interconnected operation with the throttle. The propeller control has a similar latch, though with only one claw. The latch is used to keep the prop control ahead of the throttle when advancing power. Always leave the latch on the prop handle extended. The latch on the boost lever will be retracted for normal operation.
The turbo and throttle can be used interconnected from takeoff through all altitudes. A governor on the turbo-supercharger prevents overspeeding at high altitudes (See section on Turbo-supercharger.) However, do not use the controls interconnected, except: When you need a quick response of power, or You are making a takeoff with water injection. The provision for interconnected controls was made for these two purposes.
Under ordinary conditions advance your throttle full forward; then afterwards push your boost lever forward to supply the additional manifold pressure required. There is a sound reason for this procedure. You have an engine-driven impeller as well as the turbo-supercharger. Operation fo the impeller costs the engine about 300 hp which otherwise could be delivered to the propeller. Take advantage of this impeller as long as it will deliver the necessary power without pnalizing your engine still further by cutting in another supercharger--the turbo.

Automatic Engine Control
Beginning with the P-47N-25, engine and turbo-supercharger will be regulated by a single Automatic Engine Control. By means of bellows, solenoids, electric motors and so on, the single lever operates the butterfly valve in the carburetor and the turbo waste gates to bring about the most efficient combination of throttle and supercharger to obtain a desired manifold pressure.
The throttle quadrant on planes equipped with Automatic Engine Control is the same as on earlier series, except there is no "B" or turbo control lever.