best medium bomber

[tomo pauk]

Dave, the Pe-2 with M-105/VK-105 engine was good for 320 mph, give or take. Same with seris produced Tu-2.

 

[Shortround6]

It is not speed but actually survivability while carrying a useful bomb load over a useful range.

Speed may mean survivability if it is high enough, 290mph, for instance isn't enough better than 270mph to really help if the fighters can do 360mph.

The Russian and German bombers not only had crap for defensive armament (generally) but had real problems with range and bomb loads and even bomb loads and speed.

External stores are always going to cut into speed and range due to drag.

The A-26 may have been able to do 355mph with 4000lbs worth of bombs inside the bomb bay, Four 1000lb bombs, speed may depend a bit on fuel load.



The Pe-2 was only going to hit 360mph in a dive, at least the M-105 powered ones. Usual max speed was more like 330mph give or take a few mph depending on exact version. Clean the PE-2 was limited to six 100kg (220lb) bombs, four in the fuselage and one in each nacelle. Operational range was just under 800 miles, again depending on exact version, production batch and factory. There were external racks for four 250kg bombs or two 500kg bombs but max bomb load is given as 1000kg which means if you put the big bombs outside the internal bays are empty. Hanging the bombs on the outside does what to the speed and range?

The Pe-2 did a lot of good work for the Russians but try plugging it into some other countries missions? It is short on bomb load for long distance missions and and long distance for the Pe-2 is rather short compared to many other planes. Want to try using Pe-2s in the Pacific or even the Med?

To be fair the A-26 once it got the water injection engines had as much power in one engine as the Pe-2 had in both. There is only so much you can do with under 1200hp engines.

The TU-2 and the Ju-88/Ju-188 have the same bomb load problem. Small internal bay/s with the majority of the load carried outside if you get anywhere near the listed maximum loads. TU-2 is a bit better. Often listed as having 1500kg of bombs inside (six 250kg bombs?)

Nobody was zipping around with these bombers at max speed and going very far. Accelerating from cruise speeds to max speeds was always going to take a while.

 

[Timppa]

Any other contender - except the "wooden wonder"- could have taken a 1,200 mile round trip from UK to Berlin, with a 4,000 lb bomb, in about 4 hours. ?
Twice in one night.

 

[tomo pauk]

Tomo - IMO, the A/B-26 never had a mission which required the 'C' series engine as the war was winding down and jet aircraft were clearly going to make sure that any a/c equipped with the 'C' series was not going to fly high enough or fast enough to warrant post production modifications.

Post WWII future operations for the Invader clearly point to the validity of the decision to not 're-engine' that great airplane. Post war my father had a P-61B night fighter squadron at Hamilton Field and had the opportunity to fly a P-61C (that never replaced the B) with the turbo supercharged R-2800-C. He liked the airplane very much but opined that the P-82 night fighter was overall superior to the P-61C. I suspect AAF planners felt the same way as the P-51C never got a production order and only a couple of F-15s came into existence as Recon version.

Bill,
I did not suggested that we make a (night) fighter from the A-26, though people were doing much wiereder stuff in ww2
The C series of the R-2800 does not improve just the hi-alt performance, but all-altitude, including take off power. Interstingly enough, AAF did not have any jet aircraft of the 'attack' class with in pipeline.

For most of the uses intended for the A-26 the "better" versions of the R-2800 might not have really done much for mission capability.
Two stage superchargers certainly do nothing for planes flying at strafing altitudes.
For the nightfighter variant or perhaps for a recon version they might have been useful.
The B-26Ks used in Vie Nam used "C" series engines. Same engines used in C-118a cargo planes ( DC-6 freighter).
A-26s in WW II got water injection from the B-45 block on. 2350hp WER at low (very low) altitude..

Te thread is about medium bombers, so if we're going to think of the attack aircraft (doing mostly strafing and low-level bombing) to be competitive in medium bomber role (all-altitude bombing, bomb aimer in lieu of nose gunpack) the installation engines better suited for hi-alts is not out of it's place. The water injection will help even more with 2-stage engine on board.

If you want a high altitude "medium" bomber then the two stage systems make sense but bombing accuracy goes to pot due to the altitude. The US had several large high altitude medium bombers "in the works" and decided it didn't want any of them.
The Martin XB-27 was a version of the Martin B-26 with a pressurized cockpit (?) and turbocharged engines but was not proceed with (built).
The North American XB-28 saw two prototypes built, Pressure cabin and turbo R-2800s

First flew 2 1/2 months before the A-26.

Looks like the Mosquitoes with 2-stage engines were pretty useful & accurate, even when bombing from 25000 ft?

 

[tomo pauk]

It is not speed but actually survivability while carrying a useful bomb load over a useful range.
Speed may mean survivability if it is high enough, 290mph, for instance isn't enough better than 270mph to really help if the fighters can do 360mph.
The Russian and German bombers not only had crap for defensive armament (generally) but had real problems with range and bomb loads and even bomb loads and speed.
External stores are always going to cut into speed and range due to drag.
The A-26 may have been able to do 355mph with 4000lbs worth of bombs inside the bomb bay, Four 1000lb bombs, speed may depend a bit on fuel load.

This is painting the Soviet and German bombers with too wide a brush, lumping the 'worst' and best together. Just because Pe-2 and Ju-88 did not have had that a good bomb bay does not mean that Tu-2 and Do-217 were in the same position. Same goes for range.
The usability of A-26's defensive armament was one fighter per defending bomber, since there was only one rear gunner. Vs. 2-3 gunners on German and Sovier bombers. Granted, the A-26 have had power turret with twin HMGs, but it's defensive firepower was less than half of what was carried on the B-25 and B-26.

The TU-2 and the Ju-88/Ju-188 have the same bomb load problem. Small internal bay/s with the majority of the load carried outside if you get anywhere near the listed maximum loads. TU-2 is a bit better. Often listed as having 1500kg of bombs inside (six 250kg bombs?)
Nobody was zipping around with these bombers at max speed and going very far. Accelerating from cruise speeds to max speeds was always going to take a while.

1500 kg - 3300 lbs. Tu-2 is head and shoulders when we compare bomb bay capacities with Ju-88 family, bar the 'big belly' models. It is also much faster when a worthwhile bomb load is carried.
The Tu-2 carried max of ~700-800 US gals of fuel internally, range (not radius, of course) of ~1250 miles.

 

[Shortround6]

Thank you for the reminder on the Do-217. A good bomb bay for a medium bomber. There are still trade offs between bomb load and fuel/range though like many other bombers. "Normal" bomb load would be about 2000kg, eight 250kg bombs or four 500kg bombs. The max internal load was two 1000kg bombs and two 250kg bombs. Americans often used odd ball combinations also in order to get impressive totals
Max load of 4000kg requires not only external storage but limits on fuel?? Range on normal internal fuel was 1200-1300 mile with 2500kg internal bomb load? Good but not great.
The DO 217 with BMW engines was fast but not fast enough, around 320 at 18,000ft?? Cruise was 258mph?? economical cruise 245mph??

And the defensive armament was crap. 4 man crew had five gun positions to man and since we really don't want the pilot leaving his seat in order to man a gun that leaves 1 or 2 very busy gunners. (OK nose gun is handled by bomb aimer leaving 2 men for 4 guns). Granted you can shoot at two incoming fighters but only if they are in the fields of fire of the appropriate guns. 2 fighters coming in together a little high and just off the tail can only be engaged by one gun. Likewise if the fighters approach from below and behind.
The A-26 may not have had the best defensive gun set up but it was way ahead of the Do-217.
You also have the power turret question. How much more effective is a gun in a power turret than manually aimed guns? Granted the sights can screw things up a bit but is the 13mm gun in a Do 217 even in a full power turret or just power traverse? And was it gross traverse under power and fine aiming being done manually?

Belly 13mm gun was manual and the 7.9 out the side windows were manual.

Tu-2 had a few issues with it's defensive guns although being a bit faster it didn't have quite the need.

 

[tomo pauk]

Do 217E was faster than 480 km/h only when weihting less than 14.5 t, ie. bomb of under 1000 kg, not too much of fuel. With 1500 kg of bombs internally, fuel just in wing tanks (15.5 t weight) it was good for 460 km/h on 2 x 1300 PS, max power of the BMW 801A in 2nd S/C gear.
Going with BMW 801D/ML and DB 603A improves performance, up to 560 km/h is claimed with later.

The Tu-2 was fast for a gun-armed bomber, but it will need fighter escort in order to survive in a contested airspace. Comments about Do 217E - the big dependance on weight to 'make' speed - certainly apply in a good measure to the Tu-2 too, even though the Tu-2 was lighter by some 2-2.5 tons empty, and a bit smaller.
As a pure bomb truck,the Do 217 was better, with 3000 kg of internal bomb load + 2960 L of fuel already in 1941.

 

[wuzak]

Looks like the Mosquitoes with 2-stage engines were pretty useful & accurate, even when bombing from 25000 ft?

These two stage bombers were generally accurate using systems such as Oboe.

Tests with the Nordern and Mk XIV bomb sights didn't give brilliant results for bombing at high altitude.

Much better results were achieved at low levels.

Low level raids had the advantage of reducing the risk of detection by radar.

 

[fastmongrel]

Were any Mosquitos fitted with the Stabilised Automatic Bomb Sight as used by 617 Sqn.

 

[wuzak]

Were any Mosquitos fitted with the Stabilised Automatic Bomb Sight as used by 617 Sqn.

Not to my knowledge.

I have copies of trials with the MkXIV and Nordern sights, as well as reports on the bombing installations of teh Mosquito which included the MkIX sight.

 

[fastmongrel]

Not to my knowledge.

I have copies of trials with the MkXIV and Nordern sights, as well as reports on the bombing installations of teh Mosquito which included the MkIX sight.

I asked because a nose through Google images shows the Bombardier/bomb aimer sitting knees either side of the Nordensight looking down into the sight with the computer cabinets to the right. We're Mossies roomy enough to allow that or were the Nordensights modified to allow a prone or crouching position.

 

[Airframes]

I doubt there'd be room in the nose of a Mossie for a Norden sight. Also, American aircraft supplied to 'foreign powers' were not allowed to have the Norden sight installed - types such as the B-24 and B-25 supplied to the RAF, for example,were normally supplied with the Sperry sight, an American version of the MkXIV sight, so it's highly unlikely that RAF aircraft would have the Norden.
The MkXIV was considered almost as good in some cases, and 'as good' in certain circumstances, to the Norden, and had the advantage that the straight and level flying time required on the bomb run was a lot less than the Norden.
The SABS was used only by 617 Sqn, and then, as far as I know, only in the Lancaster.

 

[wuzak]

I doubt there'd be room in the nose of a Mossie for a Norden sight.

It was trialled in the Mosquito.

The Legendary Avro 6 Bomb Carrier for the Mosquito

 

[Glider]

People get hung up on the max speed of aircraft including the bombers but the cruising speed was far more important to a bomber. The higher the cruising speed the less the chance of interception. Once intercepted the higher max speed was of some help but personally I would rather not be intercepted.
Its also worth remembering that the higher max speed was of little help even when intercepted if you stick to close formation, as flying in formation slows you down considerably.

The A26 defensive arrangement is in my mind very poor as periscopes limit your vision and there is a good chance you would never see the incoming fighters.

Norden bombsights were very good but not a huge leap forward in performance and again the tactics used by the USAAF didn't help. Normally everyone dropped on the lead bomber so everything depended on the one person. The skill of the one person probably had as much to do with accuracy as the bomb sight they used. Plus, if everyone drops on the lead bomber then you automatically have a huge scatter, the size of the formation.

 

[wuzak]

Norden bombsights were very good but not a huge leap forward in performance and again the tactics used by the USAAF didn't help. Normally everyone dropped on the lead bomber so everything depended on the one person. The skill of the one person probably had as much to do with accuracy as the bomb sight they used. Plus, if everyone drops on the lead bomber then you automatically have a huge scatter, the size of the formation.

The tactics were adopted because having each aircraft line up and bomb individually increased the vulnerability of the bombers.

Bombing in formation allowed them to maintain the overlapping fields of fire that was thought to give maximum protection for the bombers.

Of course, it didn't help against flak. Mind you, a couple of hundred aircraft lining up on teh same track flying straight and steady for several minutes one after another would no doubt have provided the flak batteries time to hone in on their targets.

 

[drgondog]

should be noted that the squadron bomber on lead bombardier, max one BG lead. The multi-Group and Wing were too spread out in many cases to chance 50+ bombers bombing on one individual

 

[tomo pauk]

People get hung up on the max speed of aircraft including the bombers but the cruising speed was far more important to a bomber. The higher the cruising speed the less the chance of interception. Once intercepted the higher max speed was of some help but personally I would rather not be intercepted.
Its also worth remembering that the higher max speed was of little help even when intercepted if you stick to close formation, as flying in formation slows you down considerably.

The higher speed ( max, but indeed the cruising speed) does help against Flak. Not just that it compounds the errors made by Flak crews, but also means that on the faster aircraft there will be less of shells fired.

The A26 defensive arrangement is in my mind very poor as periscopes limit your vision and there is a good chance you would never see the incoming fighters.

The B-25 and B-26 were with far greater gun firepower, with realistic possibility that more than one gunner engages the same target. Those bombers were slow by mid-and late-war standards, however.

 

[Shortround6]

The trouble with a lot of these defensive armament layouts is that they didn't work out in practice very well (or at least as well as intended/hoped).
The A-26 arrangement may not have worked as hoped but the periscopes were supposed to have a 70 degree field of view. Certainly not great but perhaps not as bad as some other gun positions. Many of the belly guns on a variety of bombers had a rather limited field of view, which is why some of them had small windows or a series of small windows on the sides of the plane to give the gunner a better view even if the gun/s he was using wouldn't point to those directions.
You also have the fire co-ordination problem. Can the gunners in two or more positions actually talk to each other? as in how good were the intercoms in various nations aircraft? You also have only a few seconds to agree on a common target before the firing opportunity may be gone.
The two turrets on the A-26 actually have a small cross over area, upper turret will fire 5 degrees below horizontal and the lower turret will fire 5 degrees above horizontal. Assuming no aircraft structure is in the way. 5 degrees is roughly 25ft at 100yds, 50 feet at 200yds, 75 ft at 300yds and so on. Not a big area of overlap but a beam attack at nearly the same altitude as the A-26 may be the most dangerous area for an attacker to be.
Most Turrets using periscopes were failures but most of them were earlier in timing than the A-26, at least a generation older? I don't know how much the A-26 system and the B-29 system had in common.
You also have the whole powered gun turret vs manual powered gun mount (very few people really used "hand held" guns.
The Russians found that the operator of the dorsal 12.7mm MG on the Pe-2 had a lot of difficulty even getting the gun to point at a 45 degree angle to the fuselage with the early mount due to the slipstream pushing on the barrel/gas tube. Later mounts/"turrets" used a wind-vane "counterbalance" to try to equalize the air pressure (drag) as the gun mount traversed. Most manually powered mounts having sever problems trying to point sideways. American beam guns having a bit of an advantage as the fuselage was big enough for the gunner to stand upright (couched/) and use leg muscles and body weight to help maneuver the gun in a way that a seated gunner could not (some mounts may allow gunner to use leg muscles to traverse seat and gun?)
For the Americans the B-25 and B-26 had 4-6 defensive guns (not counting flexible nose gun) in all but the earliest versions but never more than 4 guns in powered mounts in any version. Hundreds of B-25C/Ds had the lower turret taken out and a single .50 mounted in the tail, beam gun/s added and a single .50 firing through the floor where the turret used to be. These were done both as a rework in the US and at at least one overseas modification center. B-26s went through 3 different tail mounts with twin .50s after the first version/s had single guns. First twin mount was not powered.
Some Japanese bombers used a dorsal turret powered in traverse by bicycle pedals. Legs have more strength than arms but compared to electric motors or hydraulics?
Point of all this is that a simple gun count does not really reflect the defensive capability of the aircraft. Even large numbers of guns does not grant immunity and even B-29s could not defend themselves 100% of the time. But the goal is to get teh losses somewhere near acceptable. Slow and few guns was the worst.

 

[Shortround6]

B-25s and B-26s were actually pretty zippy in the early versions but NOT zippy enough. Since you can't keep up max speed for more than a few minutes (and it takes a few minutes at max throttle to accelerate from cruising speed to max speed so time at max speed is really limited) and running at high speed can really suck down the fuel it really isn't an option for any but short range flights or attacks using a minimum of bombs.
Speed at "max continuous" is much more realistic and for most bombers that was not fast enough for protection. Early small wing B-26 could do 1000 miles with a 3000lb bomb load at 265mph. Top speed was supposed to be 313mph. Max continuous power (2400rpm and about 42in MAP) for a pair of R-2800 engines could be close to 400 gallon an hour. Military power (2700rpm and 52in MAP was 540gal per hour or 9 gallons a minute). Cutting the speed back to around 245-250mph at 10-15,000ft cut the fuel burn down to just under 230gal an hour and add hundreds of miles of range or allow more bombs to be carried the same distance.
Medium bombers had a wide variety of attack profiles ( bomb load, speed, distance and altitude) making judgments of a few data points difficult. American bombers tended to stick with the same or similar power rated engines for their production runs while adding large amounts of equipment. Some late model American bombers were rated for smaller bomb loads than early aircraft despite gains of thousands of pounds of gross weight. The weight gain had gone into guns and armor and more fuel. In many cases the big difference in guns was not additional defensive guns but the addition of offensive guns. Late model B-26s gaining five .50 cal offensive guns and B-25s are well known as guns ships. Some A-26s had Fourteen offensive .50 cal guns and late model A-20s had six.
They paid for it in weight and drag.
I would note however that most American medium bombers could also play the outside bomb load game with all but the Martin B-26 being rated for an extra 2000lbs in outside bomb storage. Off course outside bomb racks really do a number on speed and range.

 

[Hiromachi]

I wonder why nobody mentioned Ki-67 "Hiryu". While it was classified by Japanese as heavy bomber, in western nomenclature it would perfectly fit a medium bomber due to weight and dimensions as well as bombload.
It doesnt have such a high bombload as some of the other aircraft (though Japanese bombers most often had lesser bombloads than comparable American or other designs) but it could also carry a torpedo and did that usually at nearly double range of the comparable medium bombers produced by other countries.

It also had a very good maneuverability, sustained rate of climb, was well protected and a unlike many older Japanese bombers, this one was very well armed.

Not sure if its the best medium bomber, not even sure that we can find one to be the best medium bomber since many aircraft excelled in their roles in some theaters but in others they would fail thus seeking for ultimate and overall best medium bomber may be somewhat hard. But still Ki-67 could be a strong competitor here.