Jet Lancaster range?

[AnynameIwish]

I've been reading Stanley Hooker's "Not much of an Engineer" & he describes tests with a Lancaster converted to run with two turbojets in place of two of the Merlins. Calculations showed a 4 jet version would have a speed in excess of 400mph at 30,000ft with a full bombload making it 'essentially uninterceptable'. Great and all but there's no mention of range. AIUI they were facing increasing problems with German Nightfighters late-war. I recall a discussion in another forum years back with someone who might have been uncharitably called a 'wheraboo' who argued that in a straight Britain vs Germany drawn out fight (the scenario given was Khalkin-Gol erupts into a Soviet-Japanese war resulting in no Pearl Harbour, Hitler dies accidentally & Goering thinks it better to try a Mediterranean strategy than Barbarossa. Britain is left with Lend-Lease, but not enough U.S divisions onside to try Sicily or D-Day) the Germans would have ultimately been able to stop Bomber Command & so win.

Sure, there's a lot to be said about the plausibility (or otherwise) of the hypothetical scenario - but would anyone care to take a guess at a 4 jet Lancasters combat radius in say 1944-45?

 

[Thumpalumpacus]

With jet-engines of that era, probably the range of a lawn-dart thrown against the wind.

 

[SaparotRob]

"..lawn dart thrown against the wind"…

 

[don4331]

My SWAG:
Lancaster hold ~2150 gallons of fuel @ ~6lb/gal
Mission profile requires 25% reserve - head wind/combat damage/divert to alternate field/etc
Derwent produced 1,550 lbf thrust at cruise, burns 1.17 lbs. fuel/lbf thrust
Math based on that says absolute maximum range would be ~500 miles/combat radius 1/2 that.

Basically, London to Amsterdam...

 

[buffnut453]

Bear in mind the Derwent was a LOT lighter than the Merlin. Dry weight for the latter was 1,640 lbs while the Derwent was 975 lbs. That's a total of 2,660 lbs less weight just for engines alone in a jet-powered Lancaster. That'll get you another 440+ gals of fuel, or about 20% more than the Merlin Lanc. Still won't increase the range much...but better than the original estimate.

 

[GrauGeist]

The Meteor F Mk.I, powered by two Rolls Royce W.2B/21 engines, had a range of 500 miles by summer of 1944. The Meteor was considerably lighter than a Lancaster and I cannot see how the early RR jet engines would have been any use for a heavy bomber.

 

[wuzak]

My SWAG:
Lancaster hold ~2150 gallons of fuel @ ~6lb/gal
Mission profile requires 25% reserve - head wind/combat damage/divert to alternate field/etc
Derwent produced 1,550 lbf thrust at cruise, burns 1.17 lbs. fuel/lbf thrust
Math based on that says absolute maximum range would be ~500 miles/combat radius 1/2 that.

Basically, London to Amsterdam...

1,550lb thrust cruise at sea level.

With your assumptions I get a flight time of 5.3 hours, with an average speed of 94mph (for 500 mile range).

 

[wuzak]

Bear in mind the Derwent was a LOT lighter than the Merlin. Dry weight for the latter was 1,640 lbs while the Derwent was 975 lbs. That's a total of 2,660 lbs less weight just for engines alone in a jet-powered Lancaster. That'll get you another 440+ gals of fuel, or about 20% more than the Merlin Lanc. Still won't increase the range much...but better than the original estimate.

With additional speed they probably would have lost a turret or two (I presume that's how they got a 400mph calculated figure).

That weight could be used for extra fuel.

 

[wuzak]

1,550lb thrust cruise at sea level.

With your assumptions I get a flight time of 5.3 hours, with an average speed of 94mph (for 500 mile range).

Also, fuel is ~7.39lb per UK Gallon (6.15lb per US Gallon).

That changes the flight duration to 6.6 hours.

 

[wuzak]

The Meteor F Mk.I, powered by two Rolls Royce W.2B/21 engines, had a range of 500 miles by summer of 1944. The Meteor was considerably lighter than a Lancaster and I cannot see how the early RR jet engines would have been any use for a heavy bomber.

What fuel capacity?

 

[buffnut453]

With additional speed they probably would have lost a turret or two (I presume that's how they got a 400mph calculated figure).

That weight could be used for extra fuel.

Agreed...perhaps more of a Lancastrian shape. It certainly would be more slippery through the air.

That said, the whole idea of a "jet Lancaster" seems foolish to me. As often happens in these types of threads, you start changing things and all of a sudden end up with an entirely new design. Perhaps a better option would be to accelerate development of the Canberra. Petter had the initial design in 1944 and most of the delays centred on requirements changes rather than on the fundamental feasibility of the design. A jet bomber that could fly in excess of 45,000ft would have been very useful during WW2...if we could have delivered it in time.

 

[Geoffrey Sinclair]

Lancaster: Weights for 4 Merlin XX engines and associated equipment.
5,720 Engines - dry
9 Air compressors
66 Electric starters
10 Hand turning gear
31 Constant speed governor unit
16 Vacuum pumps
168 Air intakes, hot and cold
328 Engine mountings
228 Exhausts
1,282 Cooling system and coolant
182 Oil coolers and mounting
130 Oil system, pipes, filters etc.
210 Fuel system, pipes, filters etc.
200 Engine controls
1,480 Airscrews (Rotol)
140 Fireproof bulkheads
520 Engine cowling
10,720 Total engine and airscrew weight

The question is how much of the above is still needed for jet engines.

15,336 pounds for 2130 imperial gallons of fuel (most references quote 2,154 gallons maximum, 580+383+114 inner to outer in each wing) Two saddle tanks of 400 gallons each could be fitted to the fuselage. What was 1944 British jet fuel and was it as light as 100 octane?
Lancaster fuel formula, imperial gallons = total track miles divided by 0.95 plus 200.
1,026 pounds for 114 imperial gallons of oil

261 Fixed 179 Removable pounds Front turret (FN.5A) Guns and ammunition (2,000 rounds)
320 Fixed 179 Removable pounds Mid Upper turret (FN.7) Guns and ammunition (2,000 rounds)

Maximum diving speed is put at 360 mph, altitude not given, upgrades of control surfaces may be needed.

 

[pbehn]

Any jet powered Lancaster would just have made it into service when it wasnt needed anyway and since it needed 4 enines it would have been right at the back of the queue.

 

[wuzak]

Lancaster: Weights for 4 Merlin XX engines and associated equipment.
5,720 Engines - dry
9 Air compressors
66 Electric starters
10 Hand turning gear
31 Constant speed governor unit
16 Vacuum pumps
168 Air intakes, hot and cold
328 Engine mountings
228 Exhausts
1,282 Cooling system and coolant
182 Oil coolers and mounting
130 Oil system, pipes, filters etc.
210 Fuel system, pipes, filters etc.
200 Engine controls
1,480 Airscrews (Rotol)
140 Fireproof bulkheads
520 Engine cowling
10,720 Total engine and airscrew weight

The question is how much of the above is still needed for jet engines.

15,336 pounds for 2130 imperial gallons of fuel (most references quote 2,154 gallons maximum, 580+383+114 inner to outer in each wing) Two saddle tanks of 400 gallons each could be fitted to the fuselage. What was 1944 British jet fuel and was it as light as 100 octane?
Lancaster fuel formula, imperial gallons = total track miles divided by 0.95 plus 200.
1,026 pounds for 114 imperial gallons of oil

261 Fixed 179 Removable pounds Front turret (FN.5A) Guns and ammunition (2,000 rounds)
320 Fixed 179 Removable pounds Mid Upper turret (FN.7) Guns and ammunition (2,000 rounds)

Maximum diving speed is put at 360 mph, altitude not given, upgrades of control surfaces may be needed.

These items would not be required, IMO.

31 Constant speed governor unit
168 Air intakes, hot and cold
1,282 Cooling system and coolant
1,480 Airscrews (Rotol)

A weight saving of 2,961lb. Equivalent to ~400 imperial gallons of fuel.

The engines will be reduced in weight:
5,720 Engines - dry for the Merlins
3,900 Engines - dry for the Derwent I

A saving of 1,820lb.
Total savings: 4,781lb (~645 imperial gallons of fuel)

These items may, or may not, increase in weight:
328 Engine mountings
228 Exhausts (jet pipe for jet Lancaster)
66 Electric starters
182 Oil coolers and mounting
130 Oil system, pipes, filters etc.
210 Fuel system, pipes, filters etc.
9 Air compressors
200 Engine controls
520 Engine cowling

Not sure if these would be necessary for a jet powered Lancaster
10 Hand turning gear (for starting/)
16 Vacuum pumps (for powered controls?)
140 Fireproof bulkheads

If teh turrets are removed, the saving is 939lb, though that may be offset by extra body panelling.

261 Fixed 179 Removable pounds Front turret (FN.5A) Guns and ammunition (2,000 rounds)
320 Fixed 179 Removable pounds Mid Upper turret (FN.7) Guns and ammunition (2,000 rounds)

 

[wuzak]

That said, the whole idea of a "jet Lancaster" seems foolish to me. As often happens in these types of threads, you start changing things and all of a sudden end up with an entirely new design. Perhaps a better option would be to accelerate development of the Canberra. Petter had the initial design in 1944 and most of the delays centred on requirements changes rather than on the fundamental feasibility of the design. A jet bomber that could fly in excess of 45,000ft would have been very useful during WW2...if we could have delivered it in time.

The problem for the Canberra was that the engines required for its performance were not yet available.

A jet Lancaster could have been made relatively quickly - possibly in modification units rather than in full production.

Getting the engines would have been the main stumbling block.

 

[buffnut453]

The problem for the Canberra was that the engines required for its performance were not yet available.

A jet Lancaster could have been made relatively quickly - possibly in modification units rather than in full production.

Getting the engines would have been the main stumbling block.

Agree with everything you're saying. I just wonder whether conversion of the Lancaster airframe to accommodate jet engines might involve some more substantial modifications. For example, is the wing spar sufficient? Given the weight loads, logic would suggest yes...plus early jets weren't that much more powerful than late-war piston engines. However, it's a concern.

 

[Thumpalumpacus]

These items would not be required, IMO.

31 Constant speed governor unit
168 Air intakes, hot and cold
1,282 Cooling system and coolant
1,480 Airscrews (Rotol)

A weight saving of 2,961lb. Equivalent to ~400 imperial gallons of fuel.

The engines will be reduced in weight:
5,720 Engines - dry for the Merlins
3,900 Engines - dry for the Derwent I

A saving of 1,820lb.
Total savings: 4,781lb (~645 imperial gallons of fuel)

These items may, or may not, increase in weight:
328 Engine mountings
228 Exhausts (jet pipe for jet Lancaster)
66 Electric starters
182 Oil coolers and mounting
130 Oil system, pipes, filters etc.
210 Fuel system, pipes, filters etc.
9 Air compressors
200 Engine controls
520 Engine cowling

Not sure if these would be necessary for a jet powered Lancaster
10 Hand turning gear (for starting/)
16 Vacuum pumps (for powered controls?)
140 Fireproof bulkheads

If teh turrets are removed, the saving is 939lb, though that may be offset by extra body panelling.

261 Fixed 179 Removable pounds Front turret (FN.5A) Guns and ammunition (2,000 rounds)
320 Fixed 179 Removable pounds Mid Upper turret (FN.7) Guns and ammunition (2,000 rounds)

Now where's that fuel going to go? Engine-weight and ammo weight is a lot more dense than fuel. 1045 gals is going to be around 6500 lbs, Where's that going to be stowed and how much farther does it get you? And what mods to the airframe do you make?

A clean-sheet design seems smarter.

 

[wuzak]

Merlin 24 ~1,500hp @ 10,000ft
Lancaster I max speed 280mph @ 10,000ft.

Assuming 70% propeller efficiency, that equates to roughly 1,400lbf thrust from each engine.

At maximum power
Merlin 24 ~1,640hp @ 2,400ft
Lancaster I max speed 268mph @ 2,000ft.

That equates to ~1,600lbf thrust.

Maximum thrust of Derwent I was 2,000lbf at sea level.

So roughly 25% more thrust at low altitude.

http://www.wwiiaircraftperformance.org/Lancaster/Lancaster_I_JB127_Climb_and_Level_Speed_Performance.pdf

http://www.wwiiaircraftperformance.org/Aircraft_Engines_of_the_World_Rolls-Royce_Merlin.pdf

 

[buffnut453]

Now where's that fuel going to go? Engine-weight and ammo weight is a lot more dense than fuel. 1045 gals is going to be around 6500 lbs, Where's that going to be stowed and how much farther does it get you? And what mods to the airframe do you make?

A clean-sheet design seems smarter.

Well, the Tiger Force Lancasters were envisaged to have a large saddle tank:

Not suggesting it was a great idea, indeed I'm not sure how it would function in Europe. Smacks of a flying zippo lighter to me. However, such a design was in the works before the end of the war.

It did actually fly, though. A couple were sent to India in mid-1944. Love the deely-boppers on the front...no idea what they were for:

 

[GrauGeist]

I believe the largest jet aircraft the Germams built, was the Ju287.

It was 60 feet long with a wingspan of 66 feet and an empty weight just shy of 27,560 pounds. With four Jumo004B engines, it's maximum speed was 347mph at roughly 23,000 feet.
The range was listed at 980 miles and since these figures were arrived at during testing, I assume it was not carrying a test warload, so that range would end up being considerably shorter.

Now with that in mind, the Lancaster is much larger and heavier. I cannot see it being powered with only four jet engines.