MOST OVERRATED AIRCRAFT OF WWII

[Conslaw]

I think the AAF did a pretty good job at using both the B-25 and the B-26 to their best advantage. The B-25 was cheaper, but the US invested in manufacturing capability for both types and for both R2600 and R2800 engines, so it made sense to use them both. The aviation geek in me thinks the Army should have never shortened the wings of the B-26, but the realist knows with the wartime pilots, it was worth marginally slowing down the plane in combat if operational and training losses could be greatly reduced, and that seems to be what happened with the longer wings.

 

[Shortround6]

Actually the larger wing didn't do a whole lot for operational safety as they raised the gross and empty equipped weights by substantial amounts and brought the wing loading to pretty much what the short span airplanes had. The long wing was introduced on the B-10 series and B-20 has twelve .50 cal guns. The four package guns on the outside of the fuselage and the tail mount was changed from manual to power operated. Different aux fuel tank set ups were used and later models got additional armor.
It may have helped for state side training with less (much less) than operational loads.

 

[fastmongrel]

I think the AAF did a pretty good job at using both the B-25 and the B-26 to their best advantage. The B-25 was cheaper, but the US invested in manufacturing capability for both types and for both R2600 and R2800 engines

How was the B25 cheaper than the B26 I dont know a great deal about either aircraft but a quick comparison on wiki shows them to be not too far apart in terms of airframe weight about 4,000 pounds. So apart from roughly 2 tons of Duralium what made one more expensive than the other.

 

[FLYBOYJ]

How was the B25 cheaper than the B26 I dont know a great deal about either aircraft but a quick comparison on wiki shows them to be not too far apart in terms of airframe weight about 4,000 pounds. So apart from roughly 2 tons of Duralium what made one more expensive than the other.

The B-26 was probably more expensive and possibly more difficult to manufacture and there could be a whole bunch of factors that contributed to that. According to common internet sources the B-26 costs $192,000 the B-25 $142,000. These prices may have varied during production.

 

[Shortround6]

And we might add are those airframe prices or complete aircraft prices.

You don't get 1850-2000hp 18 cylinder engines for the same price as 1700hp 14 cylinder engines.
You don't get 4 blade props of that size for the cost of 3 blade props.

 

[drgondog]

GFE important but weight of aluminum and quantity of rivets is a better indicator for production costs as a general rule.

 

[GregP]

Especially number of rivets. Since I do restoration, I can agree there.

That said, I've never seen a rivet total for any WWII aircraft ... though I'd certainly like to see one. Wonder if these statistics are even available? It would be illuminating.

 

[gumbyk]

Especially number of rivets. Since I do restoration, I can agree there.

That said, I've never seen a rivet total for any WWII aircraft ... though I'd certainly like to see one. Wonder if these statistics are even available? It would be illuminating.

Mossie must have been dirt cheap then...

 

[Milosh]

Game boards are full of rivet counters. They should know.

 

[GrauGeist]

Didn't there used to be "Board Reports" that had material totals required per production unit?

The report accounted for everything from engines and tires to x-amount of fasteners, x-amount of feet of hydraulic line, etc. used per serial numbered unit completed.

 

[nuuumannn]

Problem with counting rivets is that if you stuff one up, you drill it out and redo it. How many times did that happen with unskilled labour under pressure working long-as shift patterns? Pretty hard to keep track of. I don't know how they did it in wartime, but rivets are counted by weight, not quantity, You don't order the amount you need, but stipulate a weight, or just help yourself from the free-issue boards, which are stocked up by Stores.

 

[davparlr]

it was worth marginally slowing down the plane in combat if operational and training losses could be greatly reduced, and that seems to be what happened with the longer wings.

In comparing the early B-26, the B-26B-2 with the post wing change B-26B-10.

Wing area

B-2 602 sqft

B-10 659 sqft

Weight empty

B-2 22,380 lbs

B-10 24,000 lbs

Weight loaded

B-2 29,725 lbs

B-10 38,200 lbs

Wing loading empty

B-2 37 lb/sqft

B-10 36.4 lb/sqft

Wing loading loaded

B-2 49 lb/sqft

B-10 58 lb/sqft

Max speed

B-2 317 mph at 14,500 ft

B-10 282 mph at 15,000 ft

Cruising speed

B-2 260 mph

B-10 214 mph

Modifications between -2 and -10 were wing span (adding 57 sqft area), increase of 4 .50 machine guns (for data base aircraft), miscellaneous internal equipment, and empennage update (?).

Assumption. Referenced performance data taken at loaded weight.

As can be seen, there is a significant performance between the -2 and -10 aircraft. The B-26 lost 35 mph in top speed, over 10%, and 46 mph from cruise speed, 18%. But the question is how much is that allocated to the form drag of the wing and how much is allocated to induced drag of the extra weight.

As an incompetent amateur aerodynamicist, I conjured up some data points. Using a drag allocation drawing for an Bf 109 (I know, there is not much similarity to a B-26 but it is an airplane and the only one I have for drag allocation), wing form drag is a significant contributor to aircraft drag, almost 40% for the Bf. Induced drag, drag due to lift, is relatively small, about 7%. After some drag computations, adding 6' to wing span is about equal in drag as adding about 8500lb to load (however, some of this load is due to the added weight of the redesigned wing). So, I would say that max speed lost by just adding the wing is 17 mph and 23 mph to cruise. Now 17 mph doesn't sound fast but at 317 mph, the Zero was only 15 mph faster than the -2, not much of an overtake , However, with a 32 mph advantage over the -10, the overtake of the Zero is twice as fast. Indeed, the Japanese at Midway considered the early pre-wing mod B-26s blazingly fast and difficult to bring down.


I think the change was more than "marginally" slowing down the plane, but rather a significant change. As Shortround6 said, added weight negated the big wing. Comparing the wing loading of the empty -2 to the -10 makes you wonder if the wing was increased for load carrying, more that reducing wing load, which it really didn't do.

The B-26 was a tough old bird and a formidable, and survivable, bomber when flown by an experienced crew.

Most data taken from "Deadly Duo" by Charles Mendenhall.

 

[Greg Boeser]

According to Peyton Magruder, the wing was changed in response to the USAAF desire to decrease wing loading. This was necessary due to the lower than design spec take off power of the early R-2800. But he then goes on to lament the massive increase in gross weight imposed on the design by the USAAF. The B-2 had marginally more powerful R-2800-41 engines, 1920 bhp for take off, compared to 1850 bhp for the -5s in the B-26, B-26A and the first 81 B-26Bs, but the B-26B-10 got no increase in power to offset the increase in gross weight.

A good "what if?" how much better would the B-26 have been with the same engines installed in the exalted A-26? We'll never know, because design improvements were halted in 1943. Even the canted wing of the F/G versions was snuck in and only retroactively approved.

 

[drgondog]

Dave - IF the values for best cruise speeds you showed above (214mph for 38,200lbs and 260mph for 29,735lbs) were the same and say that is 15000 feet, then:

Q= 108.53 psf for the -2and 73.52 psf for the -10
CL(-2) = 29725/(108.53*602) and 38200/(73.52*659)

CL(-2) = .455 and CL(-10) = .788 leading to CDi= (CL)^^2/(pi*AR*e).

AR(-2)= 65*65/602 = 7.01; AR(-10) = 71*71/659 = 7.65, assume Oswald efficiency = .85

CDi(-2) = (.455)^^2/(3.1416*7.01*.85) = .011; CDi(-10) = (.788)^^2/(3.1416*7.65*.85) = .030

At cruise, the Induced drag of the B-26B-10 is nearly 3x over the B-26B-2.

The additional Drag components lead to increased Parasite Drag Co-efficient of the -10 to account for 20% more surface area of the wing, increased surface area for the larger empennage, increased 'misc' parasite drag (independent of AoA) due to the cheek guns and leaks and surface roughness increase due to area increases, increased Form drag due to AoA to maintain .788 CL vs .455 to name a few. All the Parasite Drag components of the basic airframe (except racks, guns, are Reynolds Number dependent and the values are obtained via wind tunnel and correlated by flight tests.

The RN of the B-26B-10 at 214mph is 82% of the RN of the B-26B-2 if the mean aerodynamic chords are the same.

Net - the maximum Gross weight increase mandated by AAF is the speed and range killer, although the parasite drag increase due to the bigger wing/empennage and cheek guns are also important to the comparison of total drag between the models.

That said, Optimal cruise for a particular altitude (say 15000 feet) is that airspeed for which Induced Drag equals Parasite drag for that specific GW for that airplane. The challenge for Flight test engineers was to find the cruise settings to map the fuel flow/rpm/throttle settings around the velocity envelope.

 

[GregP]

Seems to me as if WWII was full of some pretty good aircraft from all sides. Even the ones that were "overrated" seem pretty good when they were used to their strength side.

 

[Venturi]

I have followed this thread with interest.

A question,

Below 15,000', why are you all considering the Allison engined P51 as inferior to the Merlin engined P51?

The only time fighter aircraft typically climbed above this altitude was to escort or intercept high altitude bombers... before 1944 this must not have happened much, at all.

 

[stona]

The Allison engined P51 was useless to the British in 1940 precisely because of the ever increasing altitude of combat in N W Europe. In the latter stages of the BoB the Luftwaffe was arriving at altitudes in excess of 30000 ft

 

[Venturi]

Yes, but as I said, below 15,000'. Obviously the P51 was not ready in Aug 1940.

My understanding is that the subsequent fighter combat on the Allies' side did not revolve around high altitude combat again until the bombing campaign got underway some years later.

Contrary to what sometimes appears to be widespread popular belief, fighter combat still took place in the ETO/MTO after the Battle of Britain and before strategic daylight bombing... in fact it was a very significant drain on the Luftwaffe.

My understanding is that below 15,000' the Allison engined Mustang was in fact faster than the Merlin engined Mustang. Additionally it could run at lower RPM than the Merlin which extended range, was lighter, and had better overall durability, especially in the desert as has already been brought up.

So I am curious as to why the P51A gets no love? Perhaps we need a "most underrated aircraft of WW2 thread".

 

[airminded88]

Contrary to what sometimes appears to be widespread popular belief, fighter combat still took place in the ETO/MTO after the Battle of Britain and before strategic daylight bombing... in fact it was a very significant drain on the Luftwaffe.

Although pressure was maintained over the LW by the RAF in western Europe after the BOB, it is my understanding that rodeo missions had mixed results as LW fighters simply refused to take the bait for the most part.
The strategic bombing campaing first aimed at U-boat bases in coastal France and later on gradually into Germany would alter LW priorities and the more substantial draining of assets would begin.
The fight over Africa and Russia was starting to get momentum and they would of course bring a whole new level of dynamics and strain for the LW.

Welcome aboard!

 

[stona]

Sorry, I was on my phone and meant P-40 in 1940, similar engine.

Timing is important, there is a tendency to telescope time when looking back at these events. When did the Mustang I A enter service with the RAF? Early 1942, first operational use was around May, I think.

Circus operations were carried out throughout 1941 by the available types and the low level operations (Rodeos and Rhubarbs) were relatively few when compared with the fighter sweeps (Ramrods), baited with bombers or otherwise.
There is a tendency to see the former in terms of the sort of operations carried out much later in the war. In fact in early 1941, after the BoB, no British fighter aircraft was equipped to carry bombs and intruder type raids, strafing air fields etc were relatively few. The first 'fighter-bomber' raid in Europe was carried out by Hurricanes of No. 607 Squadron on 30th October 1941. Hurricanes had carried out low level 'Rhubarbs' (attacking targets of opportunity) in the two months prior to this.

It seems to me that the British only used relatively few aircraft in low level offensive roles through 1941, before the Mustang I became available, and that they had plenty of Hurricanes (which were obsolescent in the out and out fighter role by mid 1941 in NW Europe) and then a few Whirlwinds which were looking for a role and that these served the purpose well enough.
Once the Mustang I became available in numbers it was certainly used in low level roles, army co-operation, tactical reconnaissance and low level attack. By the end of 1943 no fewer than 16 squadrons (including the Poles) were operating the aircraft in this way, which tends to argue against the British under rating the aircraft once it became available in numbers.

Cheers

Steve