The Lancaster as a potential nuclear bomber in 1945

[RCAFson]

If a careful start up, taxi, run-up and extra checklist followed because of the payload and mission, I'd say more like 10 to 20 minutes. Even in the tropics, I don't see the engine oil warming up to TO temps in less than 5 minutes. Shoot, when I fly my 172 it could take 5 minutes just to get to the run-up area and that's when I'm the only one on the field!

" cannot exceed 1min" = actual TO run. The warm-up might be 10 min. The fuel allowance for warmup and TO in a Barracuda II = 14IG (merlin32) as per the Pilots Notes. Multiply that by four for a Lancaster, which would be less than 2% of a modded Lancaster's fuel capacity.

The fuel allowance for a Lancaster I/III to warmup, TO, and climb to 20K ft was 270IG:

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

Also note that internal fuel capacity with two internal aux tanks (Wellington tanks) = 2950IG.

as per the data card. Again, the idea that you could burn 20% on warm-up, and TO alone, is wrong, unless there was some reason to extend the warmup, beyond that needed for the mission.

 

[RCAFson]

Says the internet warrior to the aircraft engineer who works on aircraft every night and has years of experience doing so...

You made a mistake and we can all see that.

 

[RCAFson]

1 minute to start engines, warm up engines, run through pre-takeoff checks, taxi to the active, and take off?

I've never done that in 20 years of flying and crewing.

Not even an aircraft on standby that has been run up, been through all the checks and shut down waiting for a mission.

See the next post. You are so quick to try and point out a perceived mistake in my post, but the idea that you would burn 20% of your fuel for warm-up and TO alone, goes right past you...

 

[nuuumannn]

ou made a mistake and we can all see that.

Prove it.

 

[nuuumannn]

See the next post. You are so quick to try and point out a perceived mistake in my post, but the idea that you would burn 20% of your fuel for warm-up and TO alone, goes right past you...

It goes past you too. You do realise Adler was a crew chief on military helicopters, don't you? So he kinda knows what he's talking about.

 

[DerAdlerIstGelandet]

See the next post. You are so quick to try and point out a perceived mistake in my post, but the idea that you would burn 20% of your fuel for warm-up and TO alone, goes right past you...

WTF is wrong with you? I didn't attack you personally, so keep your snarky comments to yourself.

I see no perceived mistake. I see an actual mistake. A plane is not going to start up, run up, warm up, taxi and take off in one minute. I made no comment about the percent of fuel burn during that time.

 

[DerAdlerIstGelandet]

The snarkiness needs to come down a notch in this thread. Everyone! Got it?

 

[FLYBOYJ]

" cannot exceed 1min" = actual TO run. The warm-up might be 10 min. The fuel allowance for warmup and TO in a Barracuda II = 14IG (merlin32) as per the Pilots Notes. Multiply that by four for a Lancaster, which would be less than 2% of a modded Lancaster's fuel capacity.

The fuel allowance for a Lancaster I/III to warmup, TO, and climb to 20K ft was 270IG:

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

Also note that internal fuel capacity with two internal aux tanks (Wellington tanks) = 2950IG.

as per the data card. Again, the idea that you could burn 20% on warm-up, and TO alone, is wrong, unless there was some reason to extend the warmup, beyond that needed for the mission.

I'm not going to discuss the fuel consumption percentage that you think you might burn during start up, taxi and takeoff until I go into the manual and see the actual numbers, as far as "the clock" is concerned - Start-up, 2 to 3 minutes, warm up, 10 minutes, taxi, 5 to 10 minutes, pre-takeoff run up, 10 minutes. You're burning a lot of fuel before you even take off.

Let's start here:

https://ww2aircraft.net/forum/attachments/lancaster-pdf.42884/

 

[RCAFson]

Prove it.

I just did. Here's a question that maybe will help you understand your error. What's the maximum fuel flow rate/hr on the engines in question? How long do you have to run the engines at max fuel flow rate (full throttle) to equal 20% fuel capacity? On a four Merlin engined aircraft this equals more than an hour!!!! Ditto for a B-29.

 

[RCAFson]

I'm not going to discuss the fuel consumption percentage that you think you might burn during start up, taxi and takeoff until I go into the manual and see the actual numbers, as far as "the clock" is concerned - Start-up, 2 to 3 minutes, warm up, 10 minutes, taxi, 5 to 10 minutes, pre-takeoff run up, 10 minutes. You're burning a lot of fuel before you even take off.

Let's start here:

https://ww2aircraft.net/forum/attachments/lancaster-pdf.42884/

WW2 USAAF/USN airforces had a formula for determining range that included a specified allowance for warmup and TO. 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.

 

[DerAdlerIstGelandet]

It goes past you too. You do realise Adler was a crew chief on military helicopters, don't you? So he kinda knows what he's talking about.

I am no expert on WW2 piston engine aircraft regarding takeoff fuel burn. I have no dog in the fight when it comes to the percent of fuel burned during that time in a Lancaster.

I know in the experience I have with modern aircraft. We were looking at about 10 to 20 minutes for a routine start to takeoff in the H60 depending on the start of the day. Probably longer. First start was always slower. Start number 2, then number 1. Wait for oil pressure, temps, etc. to come into the green. Go to fly. Perform system checks. Taxi to the a run up area where we can do checks at full power. Perform hit checks. Taxi to the active. Takeoff. Second and third starts of the day took less time.

When I would do engine runs and test flights on King Airs we were looking at about 5 to 10 minutes as well. Longer if we were taking off. Closer to the H60 as well.

The lil pistons I fly now take time too. When I go to the airfield to fly I have to start the engine. Let everything come into the green. Taxi to an area where I can do system checks at full power. Perform the checks. Taxi to the active and take off. Easily 10 to 15 minutes.

My issue here is not the percent of fuel burned. I only calculate that in pounds. My issue here is the 1 minute from start up to takeoff.

 

[FLYBOYJ]

WW2 USAAF/USN airforces had a formula for determining range that included a specified allowance for warmup and TO. 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.

Yea we are and I've used similar "formulas" displayed in chart form on civilian aircraft to calculate fuel burn during taxi and take off. You're going to calculate that into your flight. It is very unlikely you're going to shut down and top off fuel if you spend too much time on the ground and if you have any evidence of this happening during an actual combat mission, I'd like to hear about it. Bottom line, it's going to be more than one minute, even ten minutes from start up to take off in any 4 engine recip aircraft, especially if you're carrying bombs, let alone a nuke!

 

[DerAdlerIstGelandet]

I keep changing my numbers above. I'm trying to run through engine starts and takeoff from my recliner.

 

[RCAFson]

I'm not going to discuss the fuel consumption percentage that you think you might burn during start up, taxi and takeoff until I go into the manual and see the actual numbers, as far as "the clock" is concerned - Start-up, 2 to 3 minutes, warm up, 10 minutes, taxi, 5 to 10 minutes, pre-takeoff run up, 10 minutes. You're burning a lot of fuel before you even take off.

Let's start here:

https://ww2aircraft.net/forum/attachments/lancaster-pdf.42884/

max fuel flow as per page 33 is is 500IG/hr. How long do you have to burn the engines at max fuel flow to equal 20% (600IG) fuel burn? 600IG fuel burn/500IG/hr = 1.2 hours or 72minutes! C'mon, no sane pilot is going to run his engines for 72mins at full throttle during Warm-up and TO.

 

[FLYBOYJ]

max fuel flow as per page 33 is is 500IG/hr. How long do you have to burn the engines at max fuel flow to equal 20% (600IG) fuel burn? 600IG fuel burn/500IG/hr = 1.2 hours or 72minutes! C'mon, no sane pilot is going to run his engines for 72mins at full throttle during Warm-up and TO.

Again, I'm not arguing your fuel flow, I'm arguing your first post about one minute on the ground! You seem to conveniently ignoring this!!!

 

[nuuumannn]

I just did. Here's a question that maybe will help you understand your error.

It was a classroom exercise using a B747 as an example and it happened years ago. I certainly don't have access to the data we used back then. The point stuck in my head though - 20% of total fuel load just to get off the ground seems a ridiculously large amount, but apparently that is what happens with the Big Birds. It's also worth remembering that with modern high bypass turbofan engines, they are ultra efficient at high altitudes, which means at cruise at height as they burn fuel and get lighter they are burning bugger all. That big fan at the front, the N1 compressor is producing all the thrust - another percentage - producing 90% of the engine's total thrust output, with the hot stuff out the back contributing the rest.

As with Adler, I'm not an expert on WW2 piston engines either, and they are very different from the aircraft I do work on, but the reality is that at MTOW on take off and establishment into the climb, more than 2% total fuel load would be being used if the big bulge of the Fat Man bomb was added into the mix, which is what the original post was about, so your figures don't take that into consideration at all.

 

[FLYBOYJ]

"Fuel consumption for TO = fuel burned for warm-up and taxi and then fuel burned at full throttle during the acceleration to TO speed, and given that the runways are less than 10K ft long, this cannot exceed ~1min. Maybe you meant two percent?"

For a Lancaster or B-29 I find 10 minutes a little hard to believe.

 

[FLYBOYJ]

The only way I see this if an aircraft (be it a B-29 or Lancaster) is staged at the end of the runway, fueled, armed and run up with little taxi time, and even then I think 10 minutes is pushing it

 

[DerAdlerIstGelandet]

You won't get all 4 engines even started in one minute.

 

[RCAFson]

Yea we are and I've used similar "formulas" displayed in chart form on civilian aircraft to calculate fuel burn during taxi and take off. You're going to calculate that into your flight. It is very unlikely you're going to shut down and top off fuel if you spend too much time on the ground and if you have any evidence of this happening during an actual combat mission, I'd like to hear about it. Bottom line, it's going to be more than one minute, even ten minutes from start up to take off in any 4 engine recip aircraft, especially if you're carrying bombs, let alone a nuke!

I've already explained that the one minute referred to the TO run alone. I assumed this would be obvious as this is when the engines are going to be running at full throttle.

Warm up for ten minutes = about 1-1.5GPM/engine or about 40-60IG and then 1 minute max power for TO = 1/60 x 500IG/hr = 8.3IG and then we get between ~50-70IG