1. #1
    Hi guys,

    I just wanted to know if there was a major technical difference between the D22 and the D27, apart from the bubble canopy and the different propeller?

    I also wanted to know how many bubble canopy P47 there was compared to the Razorbacks. Were bubble canopy (and new prop equipped) present in large numbers or were they a minority (late 44 until the end).

    Thanks
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  2. #2
    ytareh's Avatar Senior Member
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    Get yerself a copy of IL2 Compare online !It tells me that (surprisingly) the 22 is a little (15kmh)faster ABOVE 8500m but 30kmh slower at all other alts .The 27 turns and climbs better again except its slightly slower in a climb above 8250m.Of course while youre not going to get a better combat flight sim the 'real life' figures dont always compare perfectly with in game ones ...
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  3. #3
    JtD's Avatar Senior Member
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    The D-22 and the D-27 had the same propeller.

    Besides the bubble top canopy, the biggest difference were the tank capacities for fuel and ADI.

    Also the engine got cleared for a higher boost as the bubble tops appeared, but this should not be a difference since earlier versions could also use this higher boost.

    In game, the story is different with the D-27 simply using an engine with more power down low (higher boost modelled).

    The bubble tops would be more numerous by late 1944 than the razorbacks.
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  4. #4
    a long time wish of mine is that the ingame D-22 and D-27 would get the same performance (at least almost....), means D-22 should perform like the D-27

    so that their only difference would be the cockpit - and could fly together, as in real.

    there would still be the D-10....
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  5. #5
    Thank You guys,

    i'm discovering the Tbolts, so i cannot really talk about their respective performances in game (not to talk about real world where i am even more ignorant ...)

    If i understood clearly, D-22 and D-27 are exactly the same aircraft, the only difference being the canopy (the Razorback definitely having the most beautiful one ) .

    BTW JTD what is the ADI thing you mentionned? And according to you which one of the two is closer to the real thing, from what i understood you seem to consider the D-27 a bit "overmodelled" down low?
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  6. #6
    Buzzsaw-'s Avatar Senior Member
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    Salute

    The boost levels and weight of the aircraft are the main differences. Wing area was the same.

    The D10 was 13,500 lbs normal loaded (full fuel and ammo, no bombs/rockets/droptanks) It was equipped with the Pratt and Whitney R-2800-63 engine. It came standard with Water injection which allowed the use of 56 inches of boost. Water injection capability was added to the earlier R-2800-21 engine beginning with the D-4-RA and D-5-RE P-47 production blocks. Provision was made for the mounting of 15-gallon tank carrying a water-alcohol mixture to the bulkhead just aft of the engine. A line from this tank was plumbed directly into the fuel intake. When injected into the combustion chamber, the water checked a dangerous rise in cylinder head temperature while manifold pressure was boosted. For brief instants, a 15-percent increase in engine power could be obtained, giving a maximum war emergency power of 2300 hp. In the D-5-RE, D-6-RE, and D-10-RE (D-4-RA, production blocks, the pilot manually controlled the water flow of the injector, but the injection procedure was automatically- controlled on the D-11-RE (D-11-RA) and subsequent blocks. This happened when the throttle was pushed forward into its last half-inch of travel.

    The D22 was slightly heavier than the D10, it had the 'universal wing' which allowed pods mounted underwing which allowed it to take the long range dual 108 gallon drop tanks or bombs, which the D10 could not carry. Its belly shackle mounts were also strengthened. The pods were first introduced on the P-47D-15 model. The D22 used the R-2800-59 engine, which also had Water injection and also ran 56 inches of boost and 2300 hp from the factory. The D22 also had standard a larger (13- foot diameter) paddle-bladed propeller (either a Hamilton Standard Hydromatic 24E50-65 or a Curtiss Electric C542S) to make full use of the additional power provided by water injection. It added 400 feet per minute to the climb rate. Unfortunately, the game D22 does not show the performance gain realized by the paddle blade addition. All earlier models of the P-47D were retroactively fitted with the Paddle blade props in late December '43 and early January '44.

    The D27 was 14,600 lbs normal loaded, also used the R-2800-59 engine, but experience in Europe had shown this engine could be easily boosted to 64 inchs when using 100/130 octane and Water injection, which gave 2535 hp and this had become standardized in Production models beginning with the D25. Earlier P-47D models, (including the D22) equipped with either the R-2800-21 with Water injection, R-2800-59, or R-2800-63 were officially cleared to use 66 inches of boost with 100/130 operationally by January of 1944. The other major difference between the D27 and the D22 was obviously the bubble canopy, but it also had an 83-gallon auxiliary fuel tank fitted internally, which added extra weight.

    The final game model, the P-47D (late) is simply a D-27 running 70 inches of boost and Water injection with 100/150 octane fuel. This gave approx. 2700 hp. This was cleared officially for operations by July of 1944.

    The game should really have modelled additional versions of the P-47, unfortunately not even the various modders have done this even though it would not require graphics changes.

    Missing models

    1) D10 using 64-65 inches boost and paddle blade prop.

    2) D10 using 70 inches boost with 100/130 octane and paddle blade (this would be the best performing P-47, with low weight/high horsepower, better handling properties of the Razor back without underwing pods) Robert Johnson, the 2nd highest scoring P-47 pilot flew a P-47D-5 named 'Lucky' similar to a D10, which was upgraded with water injection. His crew chief modded it to allow 70 inches boost, and according to Johnson, this was the best P-47 he flew in Europe. It was destroyed by another pilot who borrowed it for a mission Johnson missed. According to Johnson and other pilots, 70 inches of boost was not a problem with 100/130 octane. This level of boost was commonly used for the P-47's based on the continent, even though 100/130 octane fuel was the only variety available to the 9th AAF Groups there.

    Picture of Johnson's D5:



    3) D22 with 64-65 inches of boost and Paddle blade prop

    4) D22 with 70 inches of boost using 150 octane and Paddle blade (Razorback P-47's were still the most numerous version of the aircraft right up to September of 1944, after the introduction of 100/150 octane and clearance for 70 inchs of boost in the 8th AAF)
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  7. #7
    It would be cool to have more models but to include retrofitted early D models would be a bit redundant. The advent of ADI was not well understood even when put into use in '43, and even then the PW-R2800 components had to be engineered to handle higher boost settings. The likelihood of a pilot flying a D-10 or earlier with more than a standard output would not be surprising, but it wouldn't be until newer technology was shipped in on the newer models, where said retrofitting could occur. So i ask, why include the retrofitted model when the later model would have similar performance?
    The loaded weights have more to do with the fuel increase than actual mass added to the airframe. In game its conceivable that both airplanes would perform pretty closely.

    BTW, the P-47D-30 was the most widely produced variant, but you would have to look to see if those numbers are more than the total number of razor backs produced. There are about 20 production blocks of Razorbacks, and only 7 production blocks of bubble tops if you include the M model.

    The D-27 and D-22 were not the same plane.
    The D-27 had a higher fuel capacity making it heavier, however it was also cleared for higher boost. The issue of ADI is not only a matter of power output but also a heat reduction method.
    The main handicap of early Ds was that they overheated in extended climbs, meaning that full power could not be used for more than a couple minutes at a time, lowering the climb rate. I've previously thought it was a power to weight issue, but it had more to do with heat. ADI and better cowling improved cooling to allow for longer extended climbs such that by the time the D-30s were out, climbs at higher power could be achieved all the way up to 40,000ft taking about 20 minutes.

    The exact outputs for different models are difficult to pin down because of the variations in boost pressure and the use of higher octane fuel:
    P-47C - the first D variants = 2000hp
    P-47D-5 - P-47D-23 = 2000hp - 2300hp
    P-47D-25 - P-47D-30 = 2300hp - 2500hp
    Late D-30 and D-40 = 2500hp - 2800hp

    These figures don't include field modifications that might be able to produce similar outputs in earlier variants.
    I would still argue that some of these numbers are understated only because the R-2800 being engineered at the factory was pushing much higher boost pressures with outputs exceeding 3500hp for 100 hours. It was both marveled and somewhat held back because of fear the technology would be devastating if it fell into enemy hands. I have not seen what the max boost pressure of the turbo system for a P-47 was but outputs achieved at the PW plant reached 150".
    It would be no surprise to me if field mods allowed higher performance but i don't think this sim should take such obscurities like that into consideration.


    Bill
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  8. #8
    Originally posted by Buzzsaw-:
    Salute

    The boost levels and weight of the aircraft are the main differences. Wing area was the same.

    The D10 was 13,500 lbs normal loaded (full fuel and ammo, no bombs/rockets/droptanks) It was equipped with the Pratt and Whitney R-2800-63 engine. It came standard with Water injection which allowed the use of 52 inches of boost. Water injection capability was added to the earlier R-2800-21 engine beginning with the D-4-RA and D-5-RE P-47 production blocks. Provision was made for the mounting of 15-gallon tank carrying a water-alcohol mixture to the bulkhead just aft of the engine. A line from this tank was plumbed directly into the fuel intake. When injected into the combustion chamber, the water checked a dangerous rise in cylinder head temperature while manifold pressure was boosted. For brief instants, a 15-percent increase in engine power could be obtained, giving a maximum war emergency power of 2300 hp. In the D-5-RE, D-6-RE, and D-10-RE (D-4-RA, production blocks, the pilot manually controlled the water flow of the injector, but the injection procedure was automatically- controlled on the D-11-RE (D-11-RA) and subsequent blocks. This happened when the throttle was pushed forward into its last half-inch of travel.

    The D22 was slightly heavier than the D10, it had the 'universal wing' which allowed pods mounted underwing which allowed it to take the long range dual 108 gallon drop tanks or bombs, which the D10 could not carry. Its belly shackle mounts were also strengthened. The pods were first introduced on the P-47D-15 model. The D22 used the R-2800-59 engine, which also had Water injection and also ran 52 inches of boost and 2300 hp from the factory. The D22 also had standard a larger (13- foot diameter) paddle-bladed propeller (either a Hamilton Standard Hydromatic 24E50-65 or a Curtiss Electric C542S) to make full use of the additional power provided by water injection. It added 400 feet per minute to the climb rate. Unfortunately, the game D22 does not show the performance gain realized by the paddle blade addition. All earlier models of the P-47D were retroactively fitted with the Paddle blade props in late December '43 and early January '44.

    The D27 was 14,600 lbs normal loaded, also used the R-2800-59 engine, but experience in Europe had shown this engine could be easily boosted to 64 inchs when using 100/130 octane and Water injection, which gave 2535 hp and this had become standardized in Production models beginning with the D25. Earlier P-47D models, (including the D22) equipped with either the R-2800-21 with Water injection, R-2800-59, or R-2800-63 were officially cleared to use 64 inches of boost with 100/130 operationally by January of 1944. The other major difference between the D27 and the D22 was obviously the bubble canopy, but it also had an 83-gallon auxiliary fuel tank fitted internally, which added extra weight.

    The final game model, the P-47D (late) is simply a D-27 running 70 inches of boost and Water injection with 100/150 octane fuel. This gave approx. 2700 hp. This was cleared officially for operations by July of 1944.

    The game should really have modelled additional versions of the P-47, unfortunately not even the various modders have done this even though it would not require graphics changes.

    Missing models

    1) D10 using 64 inches boost and paddle blade prop.

    2) D10 using 70 inches boost with 100/130 octane and paddle blade (this would be the best performing P-47, with low weight/high horsepower, better handling properties of the Razor back without underwing pods) Robert Johnson, the 2nd highest scoring P-47 pilot flew a P-47D-5 named 'Lucky' similar to a D10, which was upgraded with water injection. His crew chief modded it to allow 70 inches boost, and according to Johnson, this was the best P-47 he flew in Europe. It was destroyed by another pilot who borrowed it for a mission Johnson missed. According to Johnson and other pilots, 70 inches of boost was not a problem with 100/130 octane. This level of boost was commonly used for the P-47's based on the continent, even though 100/130 octane fuel was the only variety available to the 9th AAF Groups there.

    Picture of Johnson's D5:



    3) D22 with 64 inches of boost and Paddle blade prop

    4) D22 with 70 inches of boost using 150 octane and Paddle blade (Razorback P-47's were still the most numerous version of the aircraft right up to September of 1944, after the introduction of 100/150 octane and clearance for 70 inchs of boost in the 8th AAF)
    Salute,

    Thank you for all the informations (and pic!) you posted,it is much appreciated

    Very interesting indeed
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  9. #9
    Originally posted by BillSwagger:
    It would be cool to have more models but to include retrofitted early D models would be a bit redundant. The advent of ADI was not well understood even when put into use in '43, and even then the PW-R2800 components had to be engineered to handle higher boost settings. The likelihood of a pilot flying a D-10 or earlier with more than a standard output would not be surprising, but it wouldn't be until newer technology was shipped in on the newer models, where said retrofitting could occur. So i ask, why include the retrofitted model when the later model would have similar performance?
    The loaded weights have more to do with the fuel increase than actual mass added to the airframe. In game its conceivable that both airplanes would perform pretty closely.

    BTW, the P-47D-30 was the most widely produced variant, but you would have to look to see if those numbers are more than the total number of razor backs produced. There are about 20 production blocks of Razorbacks, and only 7 production blocks of bubble tops if you include the M model.

    The D-27 and D-22 were not the same plane.
    The D-27 had a higher fuel capacity making it heavier, however it was also cleared for higher boost. The issue of ADI is not only a matter of power output but also a heat reduction method.
    The main handicap of early Ds was that they overheated in extended climbs, meaning that full power could not be used for more than a couple minutes at a time, lowering the climb rate. I've previously thought it was a power to weight issue, but it had more to do with heat. ADI and better cowling improved cooling to allow for longer extended climbs such that by the time the D-30s were out, climbs at higher power could be achieved all the way up to 40,000ft taking about 20 minutes.

    The exact outputs for different models are difficult to pin down because of the variations in boost pressure and the use of higher octane fuel:
    P-47C - the first D variants = 2000hp
    P-47D-5 - P-47D-23 = 2000hp - 2300hp
    P-47D-25 - P-47D-30 = 2300hp - 2500hp
    Late D-30 and D-40 = 2500hp - 2800hp

    These figures don't include field modifications that might be able to produce similar outputs in earlier variants.
    I would still argue that some of these numbers are understated only because the R-2800 being engineered at the factory was pushing much higher boost pressures with outputs exceeding 3500hp for 100 hours. It was both marveled and somewhat held back because of fear the technology would be devastating if it fell into enemy hands. I have not seen what the max boost pressure of the turbo system for a P-47 was but outputs achieved at the PW plant reached 150".
    It would be no surprise to me if field mods allowed higher performance but i don't think this sim should take such obscurities like that into consideration.


    Bill

    Thank You Bill,

    A lot of info in you post too! I have now a lot to digest!

    Now i'm starting to ask myself why i did wait so long to start having interest in this bird...

    Even though this community is often called UBIzoo (and for good reasons sometime); when one have a question to ask about an aircraft one can always count on it to get good infos

    TY guys!
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  10. #10
    Wildnoob's Avatar Senior Member
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    One time I read here the roll rate of the P-47 is wrong.

    If this is truth maybe TD could fix this isn't?
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