The Lancaster as a potential nuclear bomber in 1945

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For the last time. I'm not saying you are right or wrong on your fuel burn. I took issue with a specific part of your post regarding time from engine start to takeoff, and that is what I was responding to. I still have an issue with that particular part too.

There still was never a reason for the attitude you then gave me. I acknowledged that others were being snarky as well. I told EVERYONE to tone it down, so as to not single a person out, yet the attitude still continues with you for no reason at all.
 
From the UK an Allied bomber has to climb rapidly (a Lancaster will cover ~130 miles and ~255IG during a rated power climb to 20K ft as per the Pilot's Notes) to clear the AA along the Axis coastline and over Europe itself. From Tinian, there's ~1400 miles of open ocean to cross before reaching Japan. A bomber flying from Tinian needs to just get airborne to maybe ~1000ft and then it can begin a low power cruise climb to cruising altitude. At ~150 miles from Japan, the aircraft will begin a higher power climb to combat altitude, but by then the aircraft will be ~10K lbs lighter than at TO due to fuel burn.
 
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And agree 100%
 

For an essentially single aircraft mission, where fuel conservation is of the essence, about 10min. Beyond that time, the tanks will have to be topped up before TO.
 
RCAFson said:
For an essentially single aircraft mission, where fuel conservation is of the essence, about 10min. Beyond that time, the tanks will have to be topped up before TO.
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For a single aircraft mission (like a nuke strike) possibly (if was staged at the end of a runway) but I never heard or read of any type of operation as such actually happening, let alone "topping off" after start up. The engine start up and pre takeoff checklist in the Lancaster Pilot's notes was 2 1/2 pages IIRC.

This would have to be done perfectly and everything "works" on the first try.
 
RCAFson said:
We are talking combat missions here and the aircraft can always be topped up prior to TO if the warm-up period is too long.
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This comment is ridiculous.

You don't just swing by the filling station on your way out. You "run what you brung".

On bombing missions in the ETO, ships could be sitting in line for nearly a half hour as the bombers ahead of them in the que were taking off.
Also, on a four-engined bomber, you start your engines in sequence, not all at once.
So you start #1 engines and let it wind up while checking the gauges to be sure everything is in order, which can take several minutes at best. Then you switch on #2 and start it, repeating the process through #4 - meanwhile, #1 has been idling for at least 12 minutes.
The proceedure for a multi-engined aircraft, especially a bomber is not as simple as some seem to think.
 

I am assuming that fuel conservation is critical. Minimum airborne fuel flow = 96IG/hr so even at 20min for warm-up, and assuming a fuel burn far more than during ground engine idle, we have used only 32IG and that leaves 2min for full power engine run-up and TO (~17IG) , and we have still used less than 50IG of fuel.

Distance to Hiroshima, with some diversion to Iwo Jima is about 1500 air miles to ~150 miles from the Japanese coast. If we assume .9AMPG average then we've burned ~1700IG and ~12300lb of fuel. The aircraft is now climbing at an AUW of 57700lb. As per Enola Gay we take 1hr20min (80min) from beginning of our climb from final cruise alt (15kft) to bomb release at 31060ft at 285* TAS (from the Enola Gay log) but our Lancaster VI would probably drop at 29-30K ft. During that 80min our max fuel burn can be no more than about .5 AMPG or about 650IG (this is way too high because the engines are well above their FTH - 500IG is more realistic) and thus at bomb release we have burned a max of 2350IG (but ~2200IG is more likely) and now have ~650IG (or ~800IG ) for the flight to Okinawa, which is quite sufficient. Aircraft weight at 20min prior to bomb release is ~54000lb and thus a service ceiling of ~33k ft.**

Enola Gay log:
Hiroshima Log of the Enola Gay (* the speeds in the log must be knots because the aircraft has been flying at a ground speed of ~220 average from 0255 (TO) to 0755 (begin climb to combat altitude) so statute miles doesn't make sense. Enola Gay TO was at ~0245 but the first log entry is at 0255.

**With medium altitude rated Merlin 85 engines; with Merlin 86 engines service ceiling would be somewhat higher.
 
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GrauGeist said:
Almost tempted to switch each word "Lancaster" with the word "P-39"...
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It's a ~2200 statute mile mission from Tinian-Iwo Jima-Hiroshima-Okinawa. It's completely doable in a Lancaster VI.

BTW, this was the planning in case of diversion to Iwo Jima:

The Army and the Atomic Bomb, (p.536 )

The final briefing took place at
midnight, and the weather planes de-
parted for the target area. Hiroshima
was the primary target, Kokura sec-
ond, and then Nagasaki (see Map 7).
In the meantime, a C-54 had car-
ried Colonel Kirkpatrick and a crew
from the technical group to Iwo Jima
to stand by to transfer the bomb to a
spare B-29 if the strike aircraft had to
land there.
 
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They used trucks for fueling at Tinian.

Lancaster engine start up:

 
RCAFson said:
They used trucks for fueling at Tinian.

Lancaster engine start up:

Click to expand...
First, this is an edited video so the time from turning three to turning one is more than is shown. However, it is clear that you can get all four Merlins in a Lancaster turning and burning in less than twelve minutes.

Second, I'm pretty sure this was not a cold start but that the engines had been pre-run. Would you pre-run a Lancaster with a loaded Atomic payload, I'm not so sure. Would a cold start take longer than represented in the video?

Third, given that an Atomic mission would include only a single fully loaded Lancaster I think we can eliminate any delay in taxi and takeoff. Priority taxi to the runway and takeoff when correct temperatures are reached. Observation aircraft can depart prior to or after the Lancaster with the Atomic payload has departed.

Not picking sides here, just some observations...
 
Dash119 said:
Not picking sides here, just some observations...
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Solid observations.

That Lanc was not fired up cold, nor was it started for a flight.
A fighter under combat circumstances will fire off and move out of the hard stand during an alarm, but bombers have an entirely different proceedure.
And an Atomic bomber carrying one of the world's only atomic weapons sure as hell will be meticulous with it's checklist, start up and roll-out.
Any train of thought to the contrary is pure fantasy.
 
Just out of curiosity, anyone know what the time was from engine start to takeoff for either the Enola Gay or Bockscar?
Since the Lancaster is a single pilot operation, does another crewmember read a checklist(s) or does the pilot handle the entire affair himself?
 
I'm not sure how long it took between start up and rollout for Bockscar, other than they were on their way at a quarter to four in the morning.
As for the Lanc's checklist rundown, I'm not sure, perhaps one if the other guys have info on that.
 
nuuumannn said:
Only when the mythical Lancaster VI capable of carrying a Fat Man bomb with no detrimental impact on its performance whatsoever/Silverplate Lincoln is mentioned... [Stopit Nuuumannn...]
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Says the guy who claimed 20% fuel burn prior to TO... and couldn't see the obvious error in that statement.

When I did my back of envelope calculations for a Lancaster mission from Tinian, I estimated way high for fuel burn for warmup, TO, cruise, and climb to combat altitude.

We know what the AMPG is for a Lancaster with a 22000lb Grandslam being carried externally is. We know what it is for a saddle tank modded Lancaster and I used AMPG, figures far higher than for either of these aircraft.

The fact is that an Lancaster VI can fly either of the historical missions, using a Tinian->target->Okinawa flight plan.
 

The Lancaster has a Flight Engineer to assist, along with the Navigator.
 

There's no edit from #2 engine start, to #3 engine start. Again, minimum inflight fuel burn is 96IG/hr. Even 30min warmup at this rather high fuel burn rate = 48IG and then add another 2min at 8.5IG/min for full power runup and TO and we still only get 65IG fuel used. Actual consumption for 30min warmup and TO is likely to be considerably less, and 30mins warmup is way high for a fuel critical mission.
 
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