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The best 2-engined bomber in 1944-45?
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delcyros
Tech Sergeant
III GENERAL DEFENSIVE ASPECTs
As shown in the first attempt, only measurable aspects have been choosen. These conduct for negative counts, that is the more wing area, the larger the target size against gun AAA. A target which is smaller is also more difficult to spot and to track. Of course, there will be a negative count (the plane, even a small one, simply doesn´t disappear physically). Other advantages for bigger wing area are not disregarded (implying a lower wingloading and better maneuverability and slow speed handling). In my perspective, a bomber has to fullfill it´s function, not to engage in aerobatics.
This isn´t necessarely the only perspective imaginable to this subject.
Another, more general asset is weight/power relation. The more weight is accumulated on a single hp, the worse it is. All these bombers were in principle underpowered compared to modern standarts.
The He-111H by far represents the biggest target size in this comparison, roughly twice the size of the compact A-20 attack bomber. The Ar-234B has less than one third the target size of the He-111H and represents the smallest target.
The power/weight ratio also gives an idea about developmental potential of the basic airframe/ engine combination. The He-111 was considered outdated, the Do-217M was new but rapidly aging and very underpowered. This problem may have been worse, too, in the B-26, where the margin between stall speed and cruise speed is the smallest of all planes in this comparison.
Some high performance planes typically have less lbs per hp in order to attain a higher speed rating. The Ju-188A2 in particular benefits from MW-50 boost at low altitude (speed rating hasn´t been accounted for that as I was unable to find a speed graph for MW-50 boosted Ju-188A2). The piston engined A/C vary around 9.5lbs/hp +- 20% (significantly less variance than target size above). Jet engined A/C is not perfectly comparable as thrust is not power but compared to a prop driven unit, the thrust generated by a jet engine is awesome.
Note how the amount of defensive gunnery increases with negative rating. There is a significant correlation with the fitting of larger number of flexible and RPC defensive guns.
To Wuzak:
all speeds are in mph (range in st. mls., payload in lbs)
As shown in the first attempt, only measurable aspects have been choosen. These conduct for negative counts, that is the more wing area, the larger the target size against gun AAA. A target which is smaller is also more difficult to spot and to track. Of course, there will be a negative count (the plane, even a small one, simply doesn´t disappear physically). Other advantages for bigger wing area are not disregarded (implying a lower wingloading and better maneuverability and slow speed handling). In my perspective, a bomber has to fullfill it´s function, not to engage in aerobatics.
This isn´t necessarely the only perspective imaginable to this subject.
Another, more general asset is weight/power relation. The more weight is accumulated on a single hp, the worse it is. All these bombers were in principle underpowered compared to modern standarts.
The He-111H by far represents the biggest target size in this comparison, roughly twice the size of the compact A-20 attack bomber. The Ar-234B has less than one third the target size of the He-111H and represents the smallest target.
The power/weight ratio also gives an idea about developmental potential of the basic airframe/ engine combination. The He-111 was considered outdated, the Do-217M was new but rapidly aging and very underpowered. This problem may have been worse, too, in the B-26, where the margin between stall speed and cruise speed is the smallest of all planes in this comparison.
Some high performance planes typically have less lbs per hp in order to attain a higher speed rating. The Ju-188A2 in particular benefits from MW-50 boost at low altitude (speed rating hasn´t been accounted for that as I was unable to find a speed graph for MW-50 boosted Ju-188A2). The piston engined A/C vary around 9.5lbs/hp +- 20% (significantly less variance than target size above). Jet engined A/C is not perfectly comparable as thrust is not power but compared to a prop driven unit, the thrust generated by a jet engine is awesome.
Note how the amount of defensive gunnery increases with negative rating. There is a significant correlation with the fitting of larger number of flexible and RPC defensive guns.
To Wuzak:
all speeds are in mph (range in st. mls., payload in lbs)
wuzak
Captain
We know that Mosquito B.XVI cruised at 311mph with wing tanks/bombs, and 321mph without, maximum weak mixture.
http://www.wwiiaircraftperformance.org/mosquito/Mosquito_MkXVI_ads.jpg
http://www.wwiiaircraftperformance.org/mosquito/Mosquito_MkXVI_ads.jpg
delcyros
Tech Sergeant
I stand corrected.
Rating for Tu-2s changes accordingly. 3t. = 0.75 payload
sqrt(0.75*.61) =0.68 offensive rating (instead of 0.78!), which put´s it right between Ju-188A2 and A-26.
Wuzak, Do you happen to know the B Mk-XVI´s cruise rating at rich mixture? Thanks in advance
wuzak
Captain
Sorry, I don't.
Though the PR.XVI, which is generally similar, had a maximum cruising speed of 352mph @ 18,000ft (MS gear) and 366mph @ 30,000ft (FS gear).
http://www.wwiiaircraftperformance.org/mosquito/dz540.pdf
The B.IX is also similar to the B.XVI and had max cruising speeds of 334mph @ 18,400ft (MS) and 345mph @ 30,800ft (FS) at maximum weight with wing bombs mounted on faired housings.
http://www.wwiiaircraftperformance.org/mosquito/lr495-b.pdf
Max cruising speed was with 2650rpm and +7psi boost.
delcyros
Tech Sergeant
Thanks. I based the editing on the B Mk IX until further data surfaces.
The final rating shows -in principle- the sequence we have seen before. The Ar-234B wins with ca. 19 points distance to the Tu-2S, which has a very good blend between offensive rating, speed and target size in particular. Mosquito and Tu-2S changed places, the reason beeing the reconsidered speed rule (starting with 0mph rather than 200mph, otherwise we would end up with non-relational speed units).
A-26, Ju-188, Me-410A and Do-217M are within the center of the sequence, followed by Pe-2FT and A-20G, too.
The B-25 and B-26 show little to choose from. Their performances are to identic to differentiate. These two, along with the He-111H were in the process of beeing phased out, the principal conclusion from their low speed and big target size in combination with rather mediocre bombloads.
The final rating shows -in principle- the sequence we have seen before. The Ar-234B wins with ca. 19 points distance to the Tu-2S, which has a very good blend between offensive rating, speed and target size in particular. Mosquito and Tu-2S changed places, the reason beeing the reconsidered speed rule (starting with 0mph rather than 200mph, otherwise we would end up with non-relational speed units).
A-26, Ju-188, Me-410A and Do-217M are within the center of the sequence, followed by Pe-2FT and A-20G, too.
The B-25 and B-26 show little to choose from. Their performances are to identic to differentiate. These two, along with the He-111H were in the process of beeing phased out, the principal conclusion from their low speed and big target size in combination with rather mediocre bombloads.
parsifal
Colonel
del for what its worthy, I really like what you are attempting
Shortround6
Major General
I like it too but a couple of more corrections.
Late model A-20s had a twin .50 power turret on top with one .30 or .50 out the bottom.
The B-25H had a twin top turret, a twin tail mount and a single .50 out each side But how may waist gunners?, no bottom turret on the H model. Bomb load on the H was 3000lbs I believe (early models without the 75mm cannon could do 5200lbs but in a very bizarre configuration. But eight .50 cal guns weigh about 500lbs or more including mounts and ammo boxes. Even 200rpg is is another 480lbs and the 75mm cannon and ammo weigh?
B-26 had the twin top gun, twin tail mount, two single low waist/bottom guns (but one gunner) and flexible gun in the nose.
Late model A-20s had a twin .50 power turret on top with one .30 or .50 out the bottom.
The B-25H had a twin top turret, a twin tail mount and a single .50 out each side But how may waist gunners?, no bottom turret on the H model. Bomb load on the H was 3000lbs I believe (early models without the 75mm cannon could do 5200lbs but in a very bizarre configuration. But eight .50 cal guns weigh about 500lbs or more including mounts and ammo boxes. Even 200rpg is is another 480lbs and the 75mm cannon and ammo weigh?
B-26 had the twin top gun, twin tail mount, two single low waist/bottom guns (but one gunner) and flexible gun in the nose.
Your looking at 2 tons internal normal, any externals carried and range is greatly affected. With 2 tons range is about 1800km with a bigger load external you are down to 640km.
Attachments
Shortround6
Major General
Very true, but the chart you have so kindly given us (twice) seems to show a max bomb load of 3250kg. 4 short tons (2000lb) is 3636kg.
Perhaps 4 tons might have been carried but it means even less fuel, less ammo and/or crewmen left behind.
A 4 short ton bomb load seems to leave about 1550KG for crew, fuel, oil and ammo if I am interpreting the chart right?
Perhaps 4 tons might have been carried but it means even less fuel, less ammo and/or crewmen left behind.
A 4 short ton bomb load seems to leave about 1550KG for crew, fuel, oil and ammo if I am interpreting the chart right?
wuzak
Captain
A typo SR? 4 short tons would be 8000lb = 3628kg
Shortround6
Major General
could be? I am using 2.2lbs to the kg.
12kg isn't going to change things much.
12kg isn't going to change things much.
wuzak
Captain
I thought you were saying 4 short tons was 2000lb, but now I see you meant that a short ton is 2000lb and there were 4 of them.
wuzak
Captain
Do you think it would be worth seeing the raw numbers that delcyros has been using so we can refine the parameters.
The Mosquito reports I posted show that wing mounted bombs (500lbs) cost 15-18mph for all out level speed, and at least that much for cruise speed. It would be useful to see what effect external stores had on other aircraft.
The Mosquito reports I posted show that wing mounted bombs (500lbs) cost 15-18mph for all out level speed, and at least that much for cruise speed. It would be useful to see what effect external stores had on other aircraft.
Neil Stirling
Airman 1st Class
RAF data cards for the Mosquito B XVI and some other twin engine bombers.
https://dl.dropbox.com/u/93074546/RAF Twins.rar
Neil.
https://dl.dropbox.com/u/93074546/RAF Twins.rar
Neil.
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- #197
Neil Stirling
Airman 1st Class
wuzak
Captain
Thanks Neil.
