Escorts could only stay with bombers for 20-40 minutes?

[DaveBB]

I came across an article that said escort fighters could only stay with bombers for 20-40 minutes due to the higher speed and zig-zagging pattern the fighters had to fly.  The article implied this was P-51s escorting B-24s and B-17s.  It went on to say that multiple fighter squadrons had to be used to escort the bombers on different parts of the missions.

Few questions:
(1) Is this true?
(2) Why didn't the escort fighters simply slow down to a cruise speed and conserve fuel?

[MiloMorai]

There was 3 escort groups. One escorted the first stage, a second did the middle stage (bombing stage) and a third group did the egress stage. The line was approximately the Dutch/German border but on the German side of the border.

Spitfires and P-47s did the initial and egress stages, P-51s the more dangerous middle stage.

You want the escorts flying at the bomber's 180mph? Takes time to accelerate and the bogeys would be on the bombers before the fighters could get up to speed.

Suggest reading The Mighty Eighth by Roger Freeman.

[DaveBB]

Do you know how many times escort groups missed the rondevouz with bombers? Lots.  Then the German fighters had a field day.

[MiloMorai]

How many is lots?

Here is a list of the 8th AF's heaviest losses, http://www.taphilo.com/history/8thaf/8aflosses.shtml

Which were because of fighters not showing up.

[Serenity]

Do you know how many times escort groups missed the rondevouz with bombers? Lots.  Then the German fighters had a field day.

Acceleration takes time. And more gas. It's much safer to keep a constant fuel burn by maintaining a constant speed. How much of the flight will be spent at the slow cruise? How much time with fighters? Where do we draw the bingo line? How do you expect the pilot to make the calculation on when to go home with a varying fuel rate and in the middle of a fight? By keeping your speed up, you keep your burn rate stable, and you can calculate your range and bingo back home, not on the fly. Not to mention, this isn't Aces High. You can't see the fighters coming from 6k out. You may not see them until they're on top of you. Then how much good are you going half of their speed?

[GScholz]

The fighters' best cruise speed is higher then the bombers'. Going slower means burning more fuel per mile, i.e. reduced range. The P-51 could fly to Berlin and back, but not at the speed of the bombers, so they had to use a relay system. It's as simple as that.

[Chalenge]

Rendezvous was usually briefed for a particular location. Navigators did the best they could, but relative winds and obscuring clouds could have them miles off course. Even several hundred bombers can be impossible to see if you are not looking in the right location. Defending fighters could bounce the escorts before they get to rendezvous, also. Even just 300 bombers, and the stream could be as much as 1,000 bombers (I think Schweinfurt was a total of 1,070 sorties).

Still, it seems like the Cliff notes version of how it really was.

[Oldman731]

Suggest reading The Mighty Eighth by Roger Freeman.

This almost should be required reading for all AH peoples.  Don't confuse it with "Mighty Eighth" books by other authors.

- oldman

[bozon]

RAF mustangs said that escorting mosquitoes to Norway was so much better than escorting heavies or even Beaufighters, because the mossies cruise speed was about the same as the mustangs. Not to mention that cruising fast and straight make  the sortie much shorter - including the 1 hour of loiter time over the fjords.

Photorecon mossies had to slow down for their mustang escorts, at least while the latter still had their DT on.

[save]

But the Mossies did never have to encounter more than a maximum of one JG without the Sturmgruppen that where attached to the Reichverteidigung (home defense). The Sturmgruppen could have a field day when escorts where fighting the 109s of the High JG's 109s.

Also the German radars together with the shadow following ju8s where very precise in directing unescorted bombers in the bomber stream.

If they could find the Sturmgruppen before they attacked, it was nothing less of a carnage, as many as 25 pilots dead ( some of them shot in their parachutes).

After the first successes with the Sturmgruppen with their 120 * 30mm, US  threaten the Sturmgruppens of imminent death.
Some Sturmgruppen had 300% casualties during their active time, but many bombers paid the price.
 2-3 30mm was enough for a bomber (less for the very vulnerable B24s), and they where almost totally resistant to .50 fire from front or sides.
(source : Defense over Germany)
Probably the best book of the subject.

[Vraciu]

Acceleration takes time. And more gas. It's much safer to keep a constant fuel burn by maintaining a constant speed. How much of the flight will be spent at the slow cruise? How much time with fighters? Where do we draw the bingo line? How do you expect the pilot to make the calculation on when to go home with a varying fuel rate and in the middle of a fight? By keeping your speed up, you keep your burn rate stable, and you can calculate your range and bingo back home, not on the fly. Not to mention, this isn't Aces High. You can't see the fighters coming from 6k out. You may not see them until they're on top of you. Then how much good are you going half of their speed?

Depends on which side of the power curve you are on.  Flying at max endurance with a lower fuel flow will save far more gas regardless of any acceleration penalty. 

Acceleration is measured in seconds not hours. 

The gas saved over three hours by pulling back the fuel flow is not going to be erased in the time it would take to accelerate.   Obviously fuel burn wasn't the consideration unless slowing down would burn more gas during the cruise phase than weaving at a higher speed.

[Randall172]

Depends on which side of the power curve you are on.  Flying at max endurance with a lower fuel flow will save far more gas regardless of any acceleration penalty. 

Acceleration is measured in seconds not hours. 

The gas saved over three hours by pulling back the fuel flow is not going to be erased in the time it would take to accelerate.   Obviously fuel burn wasn't the consideration unless slowing down would burn more gas during the cruise phase than weaving at a higher speed.

they are going for (fuel)/distance not (fuel)/time.  They want to get to the rendezvous point with as much fuel as possible, slowing down would mean that they would be flying longer, while speeding up would mean they would be wasting fuel to drag.

[Vraciu]

they are going for (fuel)/distance not (fuel)/time.  They want to get to the rendezvous point with as much fuel as possible, slowing down would mean that they would be flying longer, while speeding up would mean they would be wasting fuel to drag.

Without performance charts you cannot say that definitively.

There is also no requirement for a single method only.  There are times when endurance (time) is more important than range.

[DaveBB]

How did the P-51s that escorted B-29s to Japan do it? Were there multiple fighter squadrons or was it a single squadron that escorted them the entire way?

[Vraciu]

How did the P-51s that escorted B-29s to Japan do it? Were there multiple fighter squadrons or was it a single squadron that escorted them the entire way?

This site has some good info. 

http://www.506thfightergroup.org/mustangsofiwo.asp