The best 2-engined bomber in 1944-45?

mhuxt · Jan 3, 2013

delcyros said:
Thanks, Wuzak, that´s definitive enough for me. I update the Mossie entries above (top speed: 408mph, cruise speed 321mph (max. weak mixture), bombload 4000lbs, range 850 (at cruise speed -but I keep the old range as I suspect other planes are reported with a range not fitting to optimum bombload)). There are different configurations possible, unfortunately that great deal of information isn´t aviable for other planes, too. The total doesn´t change much, the lower cruise speed is offsetting what it gained in top speed in the first place (0.89 top speed*0.51 cruise speed =0.454 compared to previously 0.71*0.71 =0.504).
In reflective terms the new speed data compared to the Ar-234B´s 1.0 rating is:
Nr²= topspeed*cruisespeed that results to
Nr= sqrt(topspeed rating * cruise speed rating)

1st) Ar-234B = 1.0
2nd shared) Me-410A = 0.68 (due to higher cruise speed, top speed inferior to Mossie)
2nd shared) Mosquito BMk XVI = 0.67 (better top speed but worse cruise speed)
3rd) B-18 = 0.57
4th) A-26 = 0.55
5th) Ki-67 = 0.47
6th) Tu-2S= 0.44

You've put together a most interesting approach, and should be commended for it. I confess it's the first time I've seen anyone attempt to put together a numerical analysis in a "best of..." thread.

Point of order though, the 410 cruise is still too high, according to the German doccos I have. The DB603A manual says the Maximum Continuous setting (I don't know if this is max continous rich mixture, or max continuous weak mixture, as per the mossie) is 2300 rpm at 1.2 ata.

The handbook for the 410 says at that engine setting, the max speed is 540 km/h

Accordingly, the cruise speed for the 410 can have been no higher than 335 mph. Again, I don't know if "Hoechstverlaessige Dauerleistung" compares to max rich or max weak mixture, or if the comparison can even be made (according to the Mossie pilot's notes, the difference is in the boost, rpms are the same for both.)

delcyros · Jan 6, 2013

Accordingly, the cruise speed for the 410 can have been no higher than 335 mph. Again, I don't know if "Hoechstverlaessige Dauerleistung" compares to max rich or max weak mixture, or if the comparison can even be made (according to the Mossie pilot's notes, the difference is in the boost, rpms are the same for both.)

Mhuxt,
thanks for the data, that´s solid data enough to justify a correction. From what I can tell, "Höchstzulässige Dauerleistung" is specified usually as "max. rich mixture" and "Sparleistung" -in it´s different variants as "weak mixture".

Max. cruise speed should be at a little less than 6000m from these tables (to attain the full benefit of 1.20ata rather than 1.19 ata at 6000m) Cruise speed may correspondingly be slightly higher (~5 km/h) but I´m not going to quibble on that. Noteworthy that range figures are with alarger than specified safety figure (consumption is given with 970 ltr/h instead of the 800 ltr/h from the engine manual, thus 21.25% rather than 15% specified in the table). Interesting.

I am trying to redo the analysis with some different proposition, but I will need some time to prepare.
CHANGES:
[1] Speed. the borderline min. speed referenced for normalization is the landing speed of the slowest plane of the comparison.
[2] Planes. Additional planes involved: B-26B; B-25J; HE-177A5; Pe-2FT; any more ideas?
[3] Defensive guns. The idea is to use a categorical analysis which is related to the max cruise speed. The higher the speed, the less importance is given to defensive guns. Or in other words, the slower the speed of the bomber A/C, the more defensive guns are required. Not sure, how this will be measured though, thinking about a numerical coding of nominal entries.

Glider · Jan 6, 2013

re any other aircraft, Do 217 please

delcyros · Jan 6, 2013

Ok. Will add the Do-217M. More suggestions?

Vincenzo · Jan 6, 2013

B-26G? a late A-20? a late 88 or a 188?
what's the most common in RAF? (except the Mosquito)

Shortround6 · Jan 6, 2013

Some thoughts on your changes.

"[2] Planes. Additional planes involved: B-26B; B-25J;HE-177A5 ; Pe-2FT; any more ideas?"

You can add more but it won't change the the top 2-4 any. Or shouldn't if the method is valid. Due to evolution the later planes (1944) should beat the early planes. HE-177A5 is questionable as is it a twin engine plane or a 4 engine with two props or?
Comparing an 19,000lb airplane (Pe-2FT) to a 70,000lb airplane (HE-177A5) may be stretching the ability of the analysis a bit too far.

"[3] Defensive guns."
This is a whole can of worms in itself. You cannot really not count it but how much weight should it carry? IS one or two more defensive guns (B-25s, and B-26s having 6-7 defensive guns) worth 1000lb of bomb load or several hundred miles of range?

Simple counting of guns is far from the whole story. Leaving the merits of the various guns aside (long threads in their own right) the effectiveness of the mountings is largely unknown ( or little discussed). Everybody agrees that a power turret is better than a manual mounting but by how much? Not all mounts had the same field of fire even if in the same position, like a tail mount. And in a number of cases two guns (or more?), pointing in different directions are "manned" by the same crew man. Counted as two guns or one gun with a larger field of fire?
And in the end the Defensive fire doesn't count for a whole lot as very few (if any) of these aircraft could "fight" their through unescorted ( AR 234 and Mosquito excepted and they weren't "fighting").

Glider · Jan 6, 2013

delcyros said:
Ok. Will add the Do-217M. More suggestions?

Thanks

tomo pauk · Jan 6, 2013

For what is worth, specf for the Tu-2, both serial and non-ww2 version with Mikulins:

delcyros · Jan 6, 2013

Shortround6 said:
Some thoughts on your changes.

"[2] Planes. Additional planes involved: B-26B; B-25J;HE-177A5 ; Pe-2FT; any more ideas?"

You can add more but it won't change the the top 2-4 any. Or shouldn't if the method is valid. Due to evolution the later planes (1944) should beat the early planes. HE-177A5 is questionable as is it a twin engine plane or a 4 engine with two props or?
Comparing an 19,000lb airplane (Pe-2FT) to a 70,000lb airplane (HE-177A5) may be stretching the ability of the analysis a bit too far.

My opinion is that the He-177A´s two DB-610 engines justify the qualification as a twin engined airplane. While it´s true that the Db-610 is a coupled pair of DB-605´s each, They are still in a single engine housing, sharing the same cankshaft and it´s not possible to manage any of the two coupled parts of this engine individually. Similarely as it´s not possible to manage any single cylinder star out of the two row radials which drove the A20 and A-26. Thus, a twin liquid cooled V-engine is comparapble to a twin radial one.
My expectation is that the He-177 will perform as a landmark for relative normalizations (range, payload but also- in a negative sense- size and powerweight). I am quite interested in the result and whether or not the method can be held valid for it or not.

This is a whole can of worms in itself. You cannot really not count it but how much weight should it carry? IS one or two more defensive guns (B-25s, and B-26s having 6-7 defensive guns) worth 1000lb of bomb load or several hundred miles of range?

Simple counting of guns is far from the whole story. Leaving the merits of the various guns aside (long threads in their own right) the effectiveness of the mountings is largely unknown ( or little discussed). Everybody agrees that a power turret is better than a manual mounting but by how much? Not all mounts had the same field of fire even if in the same position, like a tail mount. And in a number of cases two guns (or more?), pointing in different directions are "manned" by the same crew man. Counted as two guns or one gun with a larger field of fire?
And in the end the Defensive fire doesn't count for a whole lot as very few (if any) of these aircraft could "fight" their through unescorted ( AR 234 and Mosquito excepted and they weren't "fighting").

Good points, agreed.

delcyros · Jan 6, 2013

Vincenzo said:
B-26G? a late A-20? a late 88 or a 188?
what's the most common in RAF? (except the Mosquito)

I was thinking about the Ju-388K but discarded the idea because of the prototype stage of the airplane. Leaving the Ju-188A2 with MW-50 boosted JUMO-213AM because there was no late war Ju-88 bomber subtype (only NF derivates).
I have no idea about the RAF twin bomber for late war, the Mossie was extremely versatile.
Maybe fighter bomber P-38? Does anybody happen to know the specifics of the P-38 snoop droop, from which around 120 have been operationally used from mid44 onwards (mostly pathfinder, altough there was a proposal to use them as level bomber)?

Denniss · Jan 6, 2013

It was possible to disable/idle the engines of the DB 606/610 individually. See He 177A Exerzierkarte 4/1943, page 14-17.

Shortround6 · Jan 6, 2013

delcyros said:
My opinion is that the He-177A´s two DB-610 engines justify the qualification as a twin engined airplane. While it´s true that the Db-610 is a coupled pair of DB-605´s each, They are still in a single engine housing, sharing the same cankshaft and it´s not possible to manage any of the two coupled parts of this engine individually. Similarely as it´s not possible to manage any single cylinder star out of the two row radials which drove the A20 and A-26. Thus, a twin liquid cooled V-engine is comparapble to a twin radial one.

many sources claim that one engine or the other could be declutched? errors in old sources or?

Not sure if it helped "limp" home ability even if true. Some power on one side being better than no power but juggling throttle settings and prop pitch might be a bit difficult.

delcyros said:
My expectation is that the He-177 will perform as a landmark for relative normalizations (range, payload but also- in a negative sense- size and powerweight). I am quite interested in the result and whether or not the method can be held valid for it or not.

It may work or it may just "squish" a fair number of the results for the other aircraft into a very narrow band. I am certainly no expert in this technique though.

Denniss · Jan 6, 2013

Shortround6 said:
many sources claim that one engine or the other could be declutched? errors in old sources or?

No error

delcyros · Jan 6, 2013

I didn't knew that.
So excluded she should be, agreed.

Vincenzo · Jan 7, 2013

delcyros said:
I was thinking about the Ju-388K but discarded the idea because of the prototype stage of the airplane. Leaving the Ju-188A2 with MW-50 boosted JUMO-213AM because there was no late war Ju-88 bomber subtype (only NF derivates).
I have no idea about the RAF twin bomber for late war, the Mossie was extremely versatile.
Maybe fighter bomber P-38? Does anybody happen to know the specifics of the P-38 snoop droop, from which around 120 have been operationally used from mid44 onwards (mostly pathfinder, altough there was a proposal to use them as level bomber)?

On RAF twin bomber i've not found my paper with data but after a quick check with google i think they were a US model, Mitchell or Boston so B-25 or A-20 already mentioned.

What you think to add the classical 111 and Wellington? and G4M for the japanese navy would be not bad

Shortround6 · Jan 7, 2013

Here we have the problem of comparing early aircraft and late aircraft and trying to rate for best. The He-111 and Wellington ended with 1700hp engines (rounded off) but started with under 1000hp engines which meant certain design aspects (like wing size or bombbay) were somewhat fixed at an early stage of production. Late war bombers were designed from the start to have 1700-2000+hp engines.

Early bombers can be added to such a comparison but it won't change the top places in the list.

It may show the progress that was made over the course of the war though.

Vincenzo · Jan 7, 2013

Yes my ask to add classical was for just see the progress was made over the course of the war

Tante Ju · Jan 7, 2013

Shortround6 said:
The He-111 and Wellington ended with 1700hp engines (rounded off) but started with under 1000hp engines which meant certain design aspects (like wing size or bombbay) were somewhat fixed at an early stage of production. Late war bombers were designed from the start to have 1700-2000+hp engines.

Did later designed medium (twin) engine bombers really have a larger bomb bay or more internal capacity?

A quick glance over specs of various well known mediums doesn't really strike me of superior bomb lifting capacity for those later and supposedly 'more advanced' bombers (even the much larger Do 217 was, IIRC limited to 2.5 tons internally). I am rather more convinced that with two engines you cannot expect really more than about 2 tons of internal load. More bomb bay may require a much wider fuselage (or a very long one), at which point more engines are probably becoming the optimum configuration.

Vincenzo · Jan 7, 2013

Do 217M can load 4 tons internally but only SD (4x1000), for the SC load max would be 2800 (2x1400)

delcyros · Jan 7, 2013

Tante Ju said:
Did later designed medium (twin) engine bombers really have a larger bomb bay or more internal capacity?

A quick glance over specs of various well known mediums doesn't really strike me of superior bomb lifting capacity for those later and supposedly 'more advanced' bombers (even the much larger Do 217 was, IIRC limited to 2.5 tons internally). I am rather more convinced that with two engines you cannot expect really more than about 2 tons of internal load. More bomb bay may require a much wider fuselage (or a very long one), at which point more engines are probably becoming the optimum configuration.

Not necessarely. The Ju-288A´s internal bombbay is an example of efficient space management. It could take
[2] SC-2500 bombs
or
[2] SC-1800 bombs
or
[2] SC-1700 bombs
or
[2] PC-1400 bombs
or
[2] SC/SD-1500 bombs
or
[2] SC/SD-1000 /PC-1000RS bombs
or
[3] PC/SC/SD-500 bombs
or
[3] PC-1000 bombs
or
[8] SC-250
or
[36] SC-50

max internal bombload was a whopping 5t.

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