Eigth Air Force What-if

Back on the sadly lost TGPlanes we had long debates around this.

The general consensus was that the step up from .303 to .5 defensive mgs was largely irrelevant in a sky full of cannon-armed fighters.

The issue of which aircraft could take more punishment was more contentious, essentially because it is unprovable either way. The British did test airframes by shooting them full of holes but the paperwork was lost in floods back in the 1960s (or thereabouts). The presumed superior survivability of the B-17 is typically based on all those photos of horrendously damaged ones returning home, whereas the Lancs furnished fewer photos simply because cameras were forbidden on RAF bases. However, stories and photos of equivalent damage being survived do exist.

Higher ceiling yes, though the Lanc typically flew well below their ceiling anyway, simply to avoid those giveaway contrails.

One point in the Lanc's favour was a higher cruise speed. Made more pronounced because US bomber formations typically flew at 155mph


Edit- forgot to say, 100% agree with the level of respect for those US airmen conducting daylight raids, especially before proper escorts were available.

 

The 15th AF briefing notes generally specified bombing at 160 MPH Indicated Airspeed which at 25,000 ft correlated to approximately 245 MPH True Airspeed.

 

Thank you for the correction. I had read 155 somewhere (cannot now remember where!) but I can't argue with the briefing notes!

For comparison, a Lanc travelling at 200mph Indicated at 20,000ft (typical bombing altitude seems to have been between 18-22,000ft, I await your correction!) is going at 308mph True, if the online calculator I used is correct

 

The point being that one has to be careful that he is comparing apples to apples. The airspeeds listed in specifications by the manufacturers are in true airspeed as it makes the numbers look better to the average person. The quoted maximum airspeed for the Lancaster is 282 mph at 13,000 ft, so chances that it flew 200 mph indicated at 20,000 ft are nil. The quoted cruise speeds of the B-17 and B-24 are listed at 182 and 215 mph respectively, but we know a realistic combat cruise speed was 160 indicated.

Pilots fly by indicated airspeed as important performance parameters such as stall speed, best rate of climb, etc. are constants in IAS. Navigators use true airspeed since TAS +/- wind equals ground speed.

 

I'll just drop this in

http://www.wwiiaircraftperformance.org/Lancaster/Lancaster_I_III_ADS.jpg

Presumably that is IAS

Looking through other documents on that site for the lanc there are various cruise speeds given for 20,000 ft