Thumpalumpacus
Major
How might that affect the hypothetical jet-engined performance? What's the weight of the fuel? Pumps? Plumbing? Reinforcement for such a large tank?
Aerodynamics might be another issue, too.
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
Well, the Tiger Force Lancasters were envisaged to have a large saddle tank:
View attachment 739788
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.
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.
A clean sheet would give better performance, but likely take years longer to get to the front line.
You can have quick, affordable, or quality. Pick two.
I'd imagine that reconfiguring a Lancaster to a jet-bomber before 1945 is probably going to be a little slow, too.
You can have quick, affordable, or quality. Pick two.
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.
Those saddle tanks held 1,200 imperial gallons. Apparently the crews weren't very happy at the idea of all that petrol above their heads! So the idea was dropped.Well, the Tiger Force Lancasters were envisaged to have a large saddle tank:
View attachment 739788
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:
View attachment 739791
What fuel capacity?
Those saddle tanks held 1,200 imperial gallons. Apparently the crews weren't very happy at the idea of all that petrol above their heads! So the idea was dropped.
After briefly considering air to air refuelling, Tiger Force Lancs, or at least some of them, were due to get a 400 imp gal tank in the aft bomb bay.
Each Derwent produces 1,550lbf/burns 1813.5 lbs/hr. Multiply fuel burn by 4 for our hypothetical jet Lancaster - you've got <2hrs fuel.Just to put my calculations down for comparison.
2,150 ImpG x 7.39lb/ImpG = 15,888lb
25% reserve means 75% available => 15,888lb * 0.75 = 11,916lb.
Fuel consumption = 1,550lbf * 1.17lb/lbf/hr = 1813.5lb/hr
Endurance = 11,916lb / (1813.5lb/hr) = 6.5 hours.
So the range depends on what speed the aircraft could cruise at.
200mph * 6.5 hours = 1,300 miles
250mph * 6.5 hours = 1,625 miles
300mph * 6.5 hours = 1,950 miles
Each Derwent produces 1,550lbf/burns 1813.5 lbs/hr. Multiply fuel burn by 4 for our hypothetical jet Lancaster - you've got <2hrs fuel.
On top of that, JP4 is approx. 1/2 lb./gallon heavier than Av Gas, so you need to factor that in, as well.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.
The other factor is that jet engine fuel consumption is inversely related to altitude.
Here is the chart from a two seat aircraft powered by an uprated Nene engine. Note that operating at 10,000 metres gives an almost 50% increase in range over operating at 5,000 metres so operating the jet lanc at 33,000 ft would give a massive range improvement over operating at 16,000 and they normally operated high anyway,
View attachment 746675
Two jets, two ice engines.How would only four jet engines be able to make the Lancaster even somewhat functional?
The early jet engines simply did not have the thrust to heft such a large aircraft into the sky, let alone move it at any reasonable speed with a full bomb load.
The Lanc would need at least six to be somewhat effective and as I mentioned earlier, even the Ju287 only managed 357 mph at 27,000 feet with four Jumo004B engines.
Is that why the B-36 used a combination of propellor and jet engines?
How much fuel do you burn, in these pioneering engines, to get to that altitude?
Won't cut it, not at that point in time.