B-29 Losses

[GregP]

The B-29 regualrly cruised at 30,000 feet and could get to 33,600 feet with maximum bomb load. At these altitudes it cruised at 320 - 340 mph during the attack phase.

Most Japanese fighters of 1944 - 1945 had difficulty getting to 30,000+ feet and, if they got there, would have to accel;erate for quite awhile to get to 340 mph, aty which speed they could not even catch a B-29. I did an analysis of the lieky intercepts several years ago and concluded taht if a Japanese fighter were to make one head-on pass at a B-29 going 340 mph, and if the fighter could reach 380 mph, it would take over 35 minutes to turn around and catch the B-29, assuming it could even FIND the B-29 after the turn, and assuming it could maintain effective speed during the 180° turn to ctach the B-29.

That makes a running fight VERY improbable unless the Japanese fighter had the luxury of converging from the rear quarter, with only a 40 mph speed advantage. If so, the B-29's radar-aimed remote guns were very good at defence and any evasive action by the fighter would make for a long chase during which the fighter was more vulnerable to fire from the B-29as the B-29 was to fire from the fighter. With a 40 mph speed advantage, the approach to attack is very slow and predictable to the B-29 gunners, and the fighter appeared to be just hanging there making a great target.

While the Japnese did have a few fighter in the 400 mph+ category, they had the problem of getting to 30,000+ feet in time to make the intercept. Once they got to altitude, the engines were very hot from the extended climb and they didn't have a lot of fuel to make concerted attacks since they needed full ammunition if they were to be effectuive. The only way to lighten the aircraft for fighting at high altitude was to offload fuel, making most of the interceptors short-range aircraft.

Since we DID suffer some B-29 losses, it is apparent that while the Japanese were not completely ineffective. They were not overly effective either. One tactic, as noted above, was to send relatively few bombers from several directions, making attack a chancey operation since the bombers were not massed together.

By way of example, on the Hiroshima raid, there were only seven B-29;s in the entire raid. Three flew ahead as weather spotters. One flew to a staging area to stand by as needed. Two were photographic only and escorted the Enola Gay on the mission. So, in reality, the raid was a 3-plane raid with one or two other planes not in immediate contact with the raid aircraft around the area. They would have been difficult to stop and it would have been difficult to picik the dangerous aircraft out from the rest.

On conventional raids, a 4-plane or 6-plane raid with incendiary bombs would also have been difficult to find and stop, especially if the B-29's broke formation and scattered at 340 mph only to reform and continue some miles later. Another tactic was to fly as though intending to attack one target and turn 90° before the bomb run and attack a target that was not seemingly threatened by any radar track.

So perhaps the low losses of the B-29 Japanese raids were understandable. In Europe, much of the combat happened at 25,000 30,000 feet and the German fighters had another 40 - 50 mph on their Japanese counterparts, but the B-29's were 100 mph faster than the regular B-17 / B-24 / Lancaster attackers, so they would have been much harder targets for Luftwaffe fighters than the bomber employed were. Not saying the losses would have been comparably as low as over Japan, but they would have been much lower than happened in the real war to the real attackers.

 

[Milosh]

Before some get to carried away with the performance of the B-29, http://www.alternatewars.com/SAC/B-29_Superfortress_SAC_-_19_April_1950.pdf

 

[pinsog]

The B-29 regualrly cruised at 30,000 feet and could get to 33,600 feet with maximum bomb load. At these altitudes it cruised at 320 - 340 mph.

Most Japanese fighters of 1944 - 1945 had difficulty getting to 30,000+ feet and, if they got there, would have to accel;erate for quite awhile to get to 340 mph, aty which speed they could not even catch a B-29. I did an analysis of the lieky intercepts several years ago and concluded taht if a Japanese fighter were to make one head-on pass at a B-29 going 340 mph, and if the fighter could reach 380 mph, it would take over 35 minutes to turn around and catch the B-29, assuming it could even FIND the B-29 after the turn, and assuming it could maintain effective speed during the 180° turn to ctach the B-29.



That makes a running fight VERY improbable unless the Japanese fighter had the luxury of converging from the rear quarter, with only a 40 mph speed advantage. If so, the B-29's radar-aimed remote guns were very good at defence and any evasive action by the fighter would make for a long chase during which the fighter was more vulnerable to fire from the B-29as the B-29 was to fire from the fighter. With a 40 mph speed advantage, the approach to attack is very slow and predictable to the B-29 gunners, and the fighter appeared to be just hanging there making a great target.

While the Japnese did have a few fighter in the 400 mph+ category, they had the problem of getting to 30,000+ feet in time to make the intercept. Once they got to altitude, the engines were very hot from the extended climb and they didn't have a lot of fuel to make concerted attacks since they needed full ammunition if they were to be effectuive. The only way to lighten the aircraft for fighting at high altitude was to offload fuel, making most of the interceptors short-range aircraft.

Since we DID suffer some B-29 losses, it is apparent that while the Japanese were not completely ineffective. They were not overly effective either. One tactic, as noted above, was to send relatively few bombers from several directions, making attack a chancey operation since the bombers were not massed together.

By way of example, on the Hiroshima raid, there were only seven B-29;s in the entire raid. Three flew ahead as weather spotters. One flew to a staging area to stand by as needed. Two were photographic only and escorted the Enola Gay on the mission. So, in reality, the raid was a 3-plane raid with one or two other planes not in immediate contact with the raid aircraft around the area. They would have been difficult to stop and it would have been difficult to picik the dangerous aircraft out from the rest.

On conventional raids, a 4-plane or 6-plane raid with incendiary bombs would also have been difficult to find and stop, especially if the B-29's broke formation and scattered at 340 mph only to reform and continue some miles later. Another tactic was to fly as though intending to attack one target and turn 90° before the bomb run and attack a target that was not seemingly threatened by any radar track.

So perhaps the low losses of the B-29 Japanese raids were understandable. In Europe, much of the combat happened at 25,000 30,000 feet and the German fighters had another 40 - 50 mph on their Japanese counterparts, but the B-29's were 100 mph faster than the regular B-17 / B-24 / Lancaster attackers, so they would have been much harder targets for Luftwaffe fighters than the bomber employed were. Not saying the losses would have been comparably as low as over Japan, but they would have been much lower than happened in the real war to the real attackers.

Greg,

Would an FW190 'A' model be capable of intercepting a B29 at 30,000 feet plus? Could you do a quick analysis on German fighters attempting to intercept the B29? The 35 minute tail chase by an aircraft doing 380 mph is VERY interesting info.

 

[Siegfried]

I think some of the performance claims of the B-29 seem overstated, certainly the radar assisted rear gun for the B-29 were in use on only a few late war models primarily for night raids; perhaps in the Korean war there was something more sophisticated.

A FW 190A5 and also FW 190A8 will have a speed of about 368mph at 33,000ft and 378mph at 30,000ft which is enough to slightly outrun a B-29 at its best speed altitude.
FW 190 A-5 Performance
http://www.wwiiaircraftperformance.org/fw190/190a5-level-20-10-43.jpg

The FW 190A-9 would be better due to the BMW 801TS engine.

The FW 190D-9 about 400mph at 30,000ft.

GM-1 (Nitrous Oxide) could be used at these altitudes for a substantial boost in speed for about 15 minutes. It would have been possible to adjust supercharger speeds to improve altitude performance at a cost in low altitude performance.

The Me 198G6AS (from March 44) Me 109G14AS (from June 44) or Me 109K4 (from October 1944) or Me 109G10 (November 44) would be a better canditate for intercepting a B-29 as they had the enlarged supercharger. Even a basic Me 109G6 was probably better over 25,000ft than a FW 190.

The Fw 190A wasn't the ideal aircraft to intercept the B-29 though the FW 190A5 had pressurisation and I believe the FW 190A-10 would have had a new larger wing with a new two stage supercharger. The FW 190D-13, with a two stage supercharger would have had no trouble getting to the B-29's opperational height though the Ta 152H and TA 152C were in service before it.

Certainly the Luftwaffe was better placed to intercept B-29's than the Japanese Army and Navy were.

 

[GregP]

OK, I'll take a crack at it, but won't do an unlimited number of itterations.

1. Let's say the B-29 is at 30,000 feet and knows the attackers are Fw 190's, so they are going 335 mph.

2. Let's say it is a head-on pass with the Fw 190 at 350 mph. He makes his pass and, as they pass each other he snaps into a bank and starts a 180º turn. At 30,000 feet I doubt the Fw 190 can sustain more than about a 35° bank angle in a level turn and let's say the Fw pilot increases power and maintains 340 mph in the turn.

3. His rate of turn would be 2.586°/second and it takes him 69.62 seconds to make a 190° turn. His radius of turn is 2.036 miles and he comes out of his turn displaced 4.07 miles from the track of the B-29. Meanwhile, the B-29 has moved 6.48 miles further along it's track and the Fw 190 is displaced to the side and is a total of 7.65 miles from the B-29.

4. The Fw 190 will take some time to accelerate to his attack speed of 380 mph, but I'll assume he gets there quickly for our first-order approximation. It will take him 11.36 minutes to intercept and his closing speed is only 45 mph, making him a relative sitting duck for the B-29 tail gunner. Any evasive action just makes things take longer as the Fw 190 would decelerate in pulling hard g's.

In the Japanese calculartions, I assumed the B-29 was going 335 mph and the Japanese fighter could go only 350 mph in chase. It takes 31 minutes to ctach the B-29. The Fw is faster but is still a relative sitting duck and could not easily change that fact given the speed of the B-29. Of course, there ARE special cases where the Fw 190 would be higher than the B-29 and faster, and the time wold come down, but there are just as many cases where the Fw 190 would be lower and slower and the intercept would prove impractical to prosecute due to fuel and other possible priorities.

The speed of the B-29 is the deciding factor most of the time, which is why most B-29 pilots who have given talks at the Planes of Fame have mentioned going in fast for the attack and escape, while cruisng much more slowly to get into position for the attack and escape portion of the flight.

For you technical types, theta is the bank angle in the fighter turn, the rate of turn is found by (1091 * tangent theta) / V, with V in knots. The radius of turn is found by (V^2/(11.26 * tangent theta) with V in knots. 1 knot is 1.15078299 mph.

Milosh, thanks for making my point. Look at the speed versus altitude for the B-29 and you can see that it can get fast. According to B-29 pilots, it DID, especially when anticipating an intercept. The sky over Japan was clear many time, especially at the B-29's altitude, and they could see any fighters trying to get them ... so they accelerated and went past before the defenders could get to the height of the B-29's.

 

[Milosh]

The B-29 regualrly cruised at 30,000 feet and could get to 33,600 feet with maximum bomb load. At these altitudes it cruised at 320 - 340 mph.

Read the link again Greg.

At max load it could barely get to 24,000'. It was a one way trip from Saipan to Tokyo with max bomb load at the speeds you state.

 

[pinsog]

Milosh,

But GregP stated that pilots who he has spoken to said they flew slowly to the target, speeded up over the target to outrun the fighters, then I'm sure slowed back down and cruised slowly home, just like the F-4 and F-105 pilots did in Vietnam.

GregP, Thanks for doing the math, very interesting. Sounds like the Luftwaffe would have had their hands full with even unescorted B-29's.

 

[GregP]

Milosh, they flew at whatever load was required for the fuel and altitude they wanted to fly.

The procedure was not to go for max load, but to plan the mission for the altitude, speed, load, and range you wanted to fly to minimize the probability of an intercept.

A B-17 could haul about 20,000 pounds aloft, but could not get to Berlin and back with that load. So, they put in the ammunition, fuel and range numbers ... and came up with a 4,000 pound bomb load. The B-29 did no different. They flew high as often as possible because that minimized the Japanese reaction to the raid.

I don't need to read the link again, but thanks anyway. It is what it is and you are certainly entitled to your opinions, as am I. The pilots I have spoken with describe missions to Japan at anywhere from 22,000 to 32,000 feet depending on expected cloud cover and mission requirements. They cruised to the target area at about 220 mph and accelerated to a planned attack speed when in range of Japanese fighters. They stayed fast until they were out of Japanese fighter range and then slowed down and descended a bit to fly home.

Any speculation about the B-29 in the ETO is simply that, speculation ... except for the fact that they existed and were real assets thath could have been redpeloyed if desired. I am quite unfond of "what ifs," but I daresay it would have made an impact in the ETO, being capable of attacking about 100 mph faster than the actual heavy bombers used in the ETO. A 1000-plane raid with 20,000 pound bomb loads would have eliminated an area as a viable place to live.

At least, that is my opinion. Yours, like EPA mileage for a car, may vary and very probably does.

I KNEW someone would beg to differ on my chosen speeds by a little and it makes no difference to the outcome. The Fw 190 would have had a hard time with the B-29 regardless of slight differences in speed and that was the point ... not the exact time of intercept. Fw 190 performance fell off rapdily above 20,000 feet in the radial-powered versions and I doubt an Fw 190A could have caught a B-29 at all myself unless he was in exactly the right place at exatly the right time ... and he might very well have flown into a bullet stream from the B-29 with his slow closing speed.

The point is the situation would have different from that with the B-17's / B-24's/ Lancasters normally intercepted, and it would have been, regardless of assertions of slight speed differences. Reaction times would have been much shorter, and intercept from behind would have been hazardous due to relatively low closing speeds. if the Fw 190's had flown straight and level in trying to ntercept, don't you think they would have attracted the attention of the B-29's escorts?

Perhaps all the above is not quite true for the jets, but certainly for the pistons of all varities. And the jets never sortied very many at the same time. Don't even bring up Ta-152's. There were never enough to sortie more than about 25 at any time in history, and those were never all at the same place for any single mission ever, so thety would make no difference at all in the relative scheme of things. The B-29's, while a "what-if" in the ETO, actually existed and COULD have been sent to the ETO. The Ta-152's never existed in numbers and are a "what-if" without any possibility of being so except for the few operational planes.

In point of fact, the what-ifs are simply fiction. The reality is that the B-29 was difficult for a Japanese fighter to attack at high altitude with any degree of effectivity, and the real-life low loss rate shows it. All the ETO stuff is so much supposition and I will refrain from speculation any further on it unless there is realistic discussion without science fiction overtones.

 

[wuzak]

The B-29 performance in the ETO would depend on tactics. If they followed the mantra of mutual defence and flow in tight formations the B-29s could not have used the extra performance that was available when they were on their own. B-17s and B-24s could certainly fly and cruise faster than they did, but they were constrained by the formation.

If B-29s in the ETO were used the same way as their forebears they would be equally as vulnerable - but with better defensive armament.

Greg, your calculations are interesting. I think it shows that the idea that Mosquito bombers, particularly the ones with two stage engines, would be very difficult for the Luftwaffe to intercept on daylight raids.

The Mosquito's fast cruise was as fast as a B-29's top speed.

Also, if B-29s were sent to the ETO would there have been a bigger push for the V-3420 powered B-39? The B-39 showed nearly a 50mph increase in max speed over the B-29.

 

[pinsog]

Milosh, they flew at whatever load was required for the fueal and altitude they wanted to fly.

The procedure was not to go for max load, but to plan the mission for the altitude, speed, load, and range you wanted to fly to minimize the probability of an intercept.

A B-17 could haul about 20,000 pounds aloft, but could not get to Berlin and back with that load. So, they put in the ammunition, fuel and range numbers ... and came up with a 4,000 pound bomb load. The B-29 did no different. They flew high as often as possible because that minimized the Japanese reaction to the raid.

I don't need to read the link again, but thanks anyway. It is what it is and you are certainly entitled to your opinions, as am I. The pilots I have spoken with describe missions to Japan at anywhere from 22,000 to 32,000 feet depending on expected cloud cover and mission requirements. They cruised to the target area at about 220 mph and acceperated to a planned attack speed when in range of Japanese fighters. They stayed fast until they were out of Japanese fighter range and then slowed down and descended a bit to fly home.

Any speculation about the B-29 in the ETO is simply that, speculation ... except for the fact that they existed and were real assets thath could have been redpeloyed if desired. I am quite unfond of "what ifs," but I daresay it would have made an impact in the ETO, being capable of attacking about 100 mph faster than the actual heavy bombers used in the ETO. A 1000-plane raid with 20,000 pound bomb loads would have eliminated an area as a viable place to live.

At least, that is my opinion. Yours, like EPA mileage for a car, may vary and very probably does.

I KNEW someone would beg to differ on my chosen speeds by a little and it makes no difference to the outcome. The Fw 190 would have had a hard time with the B-29 regardless of slight differences in speed and that was the point ... not the exact time of intercept. Fw 190 performance fell off rapdily above 20,000 feet in the radial-powered versions and I doubt an Fw 190A could have caught a B-29 at all myself unless he was in exactly the right place at exatly the right time ... and he might very well have flown into a bullet stream from the B-29 with his slow closing speed.

The point is the situation would have different from that with the B-17's / B-24's/ Lancasters normally intercepted, and it would have been, regardless of assertions of slight speed differences. Reaction times would have been much shorter, and intercept from behind would have been hazardous due to relatively low closing speeds. if the Fw 190's had flown straight and level in trying to ntercept, don't you think they would have attracted the attention of the B-29's escorts?

Perhaps all the above is not quite true for the jets, but certainly from the pistons of all varities. And the jets never sortied very many at the same time. Don't even bring up Ta-152's. There were never enough to sortie more than about 25 at any time in history, and those were never all at the same place for any single mission ever, so thety would make no difference at all in the relative scheme of things. The B-29's, while a "what-if" in the ETO, actually existed and COULD have been sent to the ETO. The Ta-152's never existed in numbers and are a "what-if" without any possibility of being so except for the few operational planes.

In point of fact, the what-ifs are simply fiction. The reality is that the B-29 was difficult for a Japanese fighter to attack at high altitude with any degree of effectivity, and the real-life low loss rate shows it. All the ETO stuff is so much supposition and I will refrain from speculation any further on it unless there is realistic discussion without science fiction overtones.

Nicely written. I would say that about sums it up.

 

[GregP]

Thanks pinsog, I appreciate it. Wuzak, you have a very good point. The Mosquito was not un-interceptable, but it was a very difficult target. That probably goes a long way to explaining the low interception rate. Since the Mosquito could get up to about 390 mph (never mind the slightly faster variants), it would be VERY difficult to intercept unless the intercepting fighter was already in position and already at speed and altitude. I'm sure that happened, but not frequently. If it started to BE frequent, all the Mosquitos would have had to do was change directions some time before arriving at target, and the defenders would have been out of position to intercept.

Naturally, the other fast aircraft enjoyed the same difficulty of intercept, assuming they didn't suffer mechanical troubles that rendered them slower and vulnerable to intercept. That also assume the interceptor also didn't suffer any mechanical issues making them unsuitable for the intercept. I'm sure that happened, too.

My point was supposed to be that fast aircraft are very difficult to intercept unless the closing velocity is 100 mph or faster. Slower than that makes things very dicey if the target had rearward-firing armament. If so, you, the interceptor, appear to be moving very slowly and you make a very good target. Ditto for the bomber, but the bomber will require a lot more ammunition expended to down than the intercepting fighter with critical components located close together. 5 or 6 hits on a fighter can be SERIOUS, if well placed. On a bomber, that is unlikely but possible. That, of course, assumes MG. Cannons, with explosive shells, can be different.

 

[davparlr]

I think the B-29 would have been very effective in ETO. In addition to the above, the ETO had several advantages to the PTO. One is shorter ranges. B-29 raids from the Northern Marianas 1500+ miles to target with 20k of bombs (?), in ETO half this. This would allow a lot of airspeed/load variables. Also, while the jet stream was a bane to the PTO because they had to fly across them bucking them coming and going, the East/West routes in the ETO would benefit from these winds which neutralize each other coming and going or could be used to advantage riding them at low power setting going in and descending out of them and departing at higher cruise. Exposure time would be significantly reduced.

Also the higher altitude would offer two more advantages. One, Flak foot print would be significantly reduced, almost requiring the aircraft to fly directly overhead in order to be hit. Also, 30-35k is right in the wheel house of the P-47D and P-51D making intercepts even more risky. The Bf-109K would be challenge, but not an over powering one, and the P-47M/N were on the burner if needed.

 

[GregP]

Good points and pretty spot on. The Germans had some very good interceptors, but few and not too many pilots, propellers or gasoline by early 1945. If the B-29 had been employed there, the results would have been good for the Allies. Conversley, the Germans had the best interceotprs in the world to fight the B-29 but, by then, the Allies also had high-altitude, long-range escorts, making the task doubly tough. If the Germans flew straight and level in an attack, they were likely to attract deadly attention from an escort fighter.

I would have been interesting and deadly, but the B-29 superheavy could have done the job ... at least in my estimation.

As it is, the B-17 / B-24 / Lancaster DID the job in the event and did it quite well. Don't want to forget the Hallifax or Sterling either, but they were less numerous.

This is a complete "what-if" anyway, but there is no reason to believe the B-29, with more speed, payload, range, and armament, would fare less well than the planes that ended the ETO war. It was not more vulnerable to fire than the earlier bombers and was considerbly faster and generally higher flying in practice.

 

[Siegfried]

This is a chart comparing FW 190-A8, A9, Tq 152C and Ta 152H
http://www.wwiiaircraftperformance.org/fw190/fw190-a8-12jan45.jpg

The B-29 is easily within the envelope of both Ta 152's.

The FW 190A9 is significantly supeior to the FW 190A-8 due to the 801TS engine.

I believe this engine was already seeing modest service in 1943. It seem to have been used to power fW 190A6's used as "contact aircraft" ie lightly armed aircraft that reconoitered the bomber formation from afar and reported its disposition. The engine incorporated supercharger advances and ratio changes and used better fabrication methods in some areas such ass very fine vacuum cast cylinder fins.

I would suggest that appearance of the B-29 would lead to a response in the form of this engines production being increased even at the cost of a disproportinate decrease in standard engine production: they would have to accept the cost. GM-1 would also become a standard feature.


GM-1 would seem to add about 6000ft to the full throttle height and about 30-50km/h or 20-30mph.

Historically few german aircraft entered servive with two stage superchargers, in part this was due to reasonably good performanc of their single stage engines.

A few Jumo 213E (on Ta 152), Jumo 213F (on FW 190D-13) maybe 2-3 Ta 152C with DB603LA saw service. The BMW 801F might have had a two stage superchargers. A single Me 109K-14 with a DB605L engine might also have been delivered.

These engine would certainly be brought forward, the question is how much of the holdup was design issues and how much was related to shortages of machine tools to make the more elaborate gearboxes and impellors.

 

[GregP]

Ta-152's are relatively meaningless. There were never more than about 25 in service at any one time, and they were never in the same place for any single mission. It doesn't matter how good a plane was in WWII, if you only had 25 of them, you made no difference to the war effort. We already established their kill record was not very impressive by any standards. They shot down about 7 - 10 enemies and lost 4. The Wildcat did about as well in kill to loss ratio.

This is no disrespect for the qualities of the Ta-152. They were living desperate days in Germany when the Ta-152 came into being, and the aircraft deployed were service protoypes that were, in fact, prototypes not really ready for service. The mechanics had not been traied and there was no supply line of spare parts. When the war ended, there were only two in service. Tough to change the outcome of even a signle attack with only two working Ta-152's.

The Americans, on the ohter hand, had a LOT of B-29's and they could have actually been deployed. The Wright R-3350 was still being developed, but the planes were flying long lission and doing quite well anyway, in real life. Sure, they had some problems, but so did ALL aircraft, to a point. The fact is, the B=29 was in widespread use in quantity.

GM-1 might add 6,000 feet to the ceiling of an Fw 190, but the aircraft would be out of GM-1 by the time it got there. GM-1 was not something that could be employed for long periods of time (how big is the Nitrous Oxide tank?), and required extended maintenance when used. I can tell you that the Reno racers only use Nitrous Oxide for 2 - 3 laps because of the high tendency to blow the engine. I have used it in a car, but the bottles don't last long. And if anything goes wrong, you blow the tops out of the pistons (that assumes a wet system with solenoid valve). If the system was dry, I havent heard of it before and I believe dry Nitrous systems are a relativelty new development requiring a digital controller.

 

[Siegfried]

One of the reasons the Ta 152 was late into service was that the allied attacks on the oil industry caused the Luftwaffe to insist that its new fighters be able to opperate well on B4 fuel. This had the effect of forcing a redesign of the Jumo 213E into the E-1. The single stage Daimler Benze DB603EM also could have powered the FW 190D-9 and the Ta 152C instead of the two stage DB603LA. Waiting for the introduction of two stage intercooled engines was as much about being able to handle B4 fuel as high altitude performance. As it was the job of keeping up C3 production was quite good and the DB603EM had good altitude performance; in fact it was more powerfull at medium altitudes.

In the event of B-29's the Germans respond in some way. I would say they get the required technology into the air relatively quickly though at the expense in overall production as machine tools and skilled personel are reallocated.

Talking about the 7:4 kill ratio in favour of the Ta 152 as being a small advantage is the wrong way to look at it given the poor performance in that regard of the vastly outnumbered Luftwaffe's other fighters. That the Ta 152 was able to achieve even this is all the more remarkable.

GM-1 was not widely used on the FW-190, the Me 109G was probably more often so equiped. However it was a reaonalbly practical system. Consumtion of GM-1 was about the same as consumption of fuel itself so a 30 gallon 130L tank containing 150kg of NOX (330lb) gives a very substantial run time. For instance: assuming a 1200hp output of power consuming fuel at a sfc of 0.55 means 660lbs of fuel is burned. This means a 130L tank might last almost 30 minutues. The runs had to be limited in duration however (eg 10 minute bursts).

The reno race example of NOX damaging engines is must be taken in the context of it being applied to engines already running at 4000hp and low altitude. NOX was was applied (the way the Luftwaffe used) only above the FTH full throttle height. It was not used to increase rated engine power but only to compensate for altitude. The only stress on the engine would be that it was able to generate much higher power levels at altitudes in which the air was thinner and less able to cool the engine.

The appearance of the B-29 in ETO would illicit a response in the type of aircraft the Germans make; the emphasis on maintaining production levels at the expense of quality would I suggest be abandoned to a greater degree since existing types would be of little use even if they have use in the Easter Front.

For instance the Me 109K-1 was ready for production in late 1943, it had the aerodynamic refinements of the later Me 109K4 though a less powerfull engine. It was not produced in the interests of production despite what much have been a substantial speed advantage.

The Me 109G6ASM available from about April 1944 could manage the following speeds:
9000m (30000ft) 393mph (635kmh)
10000m (33000ft) 387mph (625kmh)
http://kurfurst.org/Performance_tests/109G14_PBLeistungen/files/PBG14_LS_SNplusMW50.jpg
(Me 109G14ASM about the same, it had a larger oil cooler)

No doubt, intereception was going to be difficult but possible.

 

[RCAFson]

Some data on the B-29 range versus payload can be found here:

http://www.alternatewars.com/SAC/B-29_Superfortress_SAC_-_19_April_1950.pdf

There's no doubt that the B-29 had impressive specs, but in 1944 it was very underdeveloped and the engines were not reliable at prolonged high power, yet to operate over Europe the B-29 would have to climb quickly to cruise altitude of 25 to 30,000 ft and use much more fuel than the SAC mission data suggests. For a mission against Berlin, and carrying a 20,000lb bomb load, I would suggest that TO weight would be 130,000 lbs. Service ceiling at this weight is about 30,000 ft and time to climb to 20,000ft would be about 45 minutes so form-up and climb to cruise would have to be done outside of Luftwaffe flak and Luftwaffe controlled airspace. Formation Cruise speed would be about 275 mph and average cruise altitude would be between 25 and 30,000 ft. These speeds would be higher than previously encountered by the Luftwaffe but neither the average speed or altitude would have been beyond the reach of the Fw-190

 

[GregP]

Nitrous Oxide does NOT burn at the same rate as fuel, particularlty fuel at cruise numbers. Gasoline contains about 24% Oxygen and NO2 (NOX is a brand name) contains about 34% Oxygen. If you burn it at the same rate, you melt your pistons in VERY short order due to running too lean. In a wet system there are two solenoids. One is for the NO2 and the other is for extra fuel to richen the mixture. It burns RAPIDLY. In a car, I could use a 20-pound bottle in about 5 minutes with a 346 cubic inch engine. With a 1650 cubic inch engine, the same 20-pound bottle would be consumed in about 1 minute flat. If I had a 330 pound tank, it would run for about 82.5 minutes ... in my car, not in the Merlin.

The Jumo 213 had 2,132.5 cubic inches and would consume the same 330 pound tank in 13.5 minutes or less since the cylinders are much bigger and burn at a faster rate than mere ratio would indicate.

The speeds for the Me 109 at 30,000+ feet are no doubt WITH GM-1, so it could achieve these speeds for a short time if the airframe were relatively new and the engine was relatively fresh and the prop was in good shape. It might well run out of NO2before closing with the B-29. Either way, it would have a slow closing speed and would face a gunner with an easy shot.

I suppose we just look at this differently. The interception is certainly possible, and I would not claim othersise. But it is MUCH more difficult than for a B-17 / B-24 / Lancaster, and that's all I'm trying to say.

As for the post immediately above, the cruise speed would be in the 250 - 257 mph range as you suggest ... up until the B-29's expected to encounter enemy attack, before which time the speed would ramp up to well over 300 mph, and I daresay they would attack from as high an altitude as possible with a 15,000 pound bomb load (chosen specifically to allow higher-altitude operation) or maybe less to allow higher altitude operation. Just my opinion.

If I were running the B-29 show (and I KNOW I'm not ...), and if I were assigned to the ETO with the B-29s, I'd take whatever precautions were necessary to exploit the new bomber and give it maximum survival potential, even at the expense of individual bomb loads. In ANY case, the bomb loads would have been more than the B-17 / B-24 / Lancaster when flying from the UK to Berlin and back in the B-29.

 

[Siegfried]

The comsumption of dinitrogen oxide was about 1:1 with the fuel consumtion rate. The Ta 152H had three rates: 50 gramms per 100 gramms, 80 gramms per 100 grams and 130 gramms per 100 grams. Rudiger Kosin's book "The German Figher 1914-1975" quotes the rate as about equal to fuel consumption. I think the book war prizes notes the three settings for the Ta 152H.

Gasoline contains NO oxygen. Small amounts are sometimes included in additives (eg alcahol)

The normal stoichiometric air fuel additon rate is 14:2 parts air to 1 part gasoline. By adding 1 part nitrous oxide one is adding about 7% more mass flow and 10% more oxygen than normal. Because the nitrous oxide is cool (being either compressed or cryogenic at -80) the latent heat of vaporisation should actually reduce the volume of the air at the inlet and reduce both supercharger and compression work. The effect of adding the nitrous at altitude will be cinsiderable as it effectively requires no work to compress due to its "charge cooling" effect. The speeds I gave for the Me 109G14ASM are WITHOUT GM-1. The kurfurst site actually has some data on GM-1 runs for the non AS versions of the Me 109G. The "AS" engine like the D engine had a greatly improved supercharger.

The weight of a nitrous oxide system with fittings, tank compares favourably with the weight and bulk of a turbo-charger or more complicated two stage supercharger.

 

[davparlr]

In the event of B-29's the Germans respond in some way. I would say they get the required technology into the air relatively quickly though at the expense in overall production as machine tools and skilled personel are reallocated.

I agree. WW2 was a continuing upgrade to weapons often to counter enemy upgrades and it occurred amazingly fast, and quite equally. Germany would would have had to counter the B-29 and would apply technology to do so. The B-29 would certainly have added complexity to the problem of attacking lumbering bombers. Increases in speed and altitude was probably a geometric increase in complexity for the defense, not only affecting power but of maneuverability and endurance. Another mile or two of altitude and a 25%+ reduction in exposure time would be a significant challenge to defensive forces. The added altitude would have little affect on the bomber in that they were flying straight and level at 20-25k and were also flying straight a level at 30-35k. It was the maneuvering fighters that was impacted. It would have applied more stress to an already stressed war machine.