XB-42?

[Niceoldguy58]

I've done some more research into my files and come up with some interesting information.

First, the Attack version(s): There were three (3) different attack nose variations proposed in Douglas April, 1944 brochure. Specifically, one nose would have a 75mm cannon with 20 rounds of ammunition and two .50 caliber machine guns with 1,000 rounds (apparently total) of ammunition. The second configuration was equipped with two automatic, high velocity 37mm cannons (once again the Air Corps' unholy fixation on getting some use out of the 37mm) with a total of 150 rounds of ammunition plus two .50 caliber machine guns with 1,000 rounds of ammunition. Finally, eight fixed, forward firing .50 caliber machine guns with a total capacity of 5,500 rounds of ammunition. It is not clear if these noses were to be interchangeable or not. From their appearance it seems that would have entailed a LOT of work on a Unit or even a Depot level, so I suspect not. My guess is that if one or more of these configurations was accepted for production there would have been a fixed number of aircraft built with each.

With regard to the change in designation from Attack-Bombardment, in late August or early September 1943 Douglas wrote to the AAF regarding the elimination of the word "Attack" from the aircraft's title, but apparently retaining the Bombardment designation. On September 8, 1943 the AAF responded by saying that the elimination of word "Attack" would not be consistent with its designation of "XA-42". Thus, the AAF invited Doulgas to comment on changing BOTH the name and designation to be "more nearly consistent its capabilities as follows: XB-42 Bombardment Type Airplane"

I don't have the documents that officially made this change, but I believe it was within 60 days of this communication from the AAF.

Finally, I have found no reference to a night-fighter version of the A/B-42. The AAF had put all its eggs into the basket of the miserably disappointing P-61 and, at this point in the war, I doubt they would wanted to add yet another mission configuration to an aircraft still very much in the very early design and development stages. Zipper, if you should have some official Douglas or AAF documents discussing this possibility I would dearly love to see them..

Respectfully submitted,

AlanG

 

[MIflyer]

Back in Dec 2017 I posed a 1940's vintage Design Analysis article on the XB-42. There was going to be an airliner version.

 

[Niceoldguy58]

I'm familiar with that airliner design. While it used a number of the XB-42 design features, I'm not sure it could be considered an airliner version of the aircraft.

Alang

 

[MIflyer]

Well, the DC-8, as it was to be called, would have had a 77 ft length rather than 53 ft and the wingspan would have been 110 ft rather than 70 ft. So it would indeed have been rather more than just a B-42 with some portholes in the bomb bay

 

[Zipper730]

While it's been about three years, I was thinking about the XB-42 design as I started looking back through old posts that I created: Does anybody have any figures, or even guesstimates, as to what the maximum load-factor of the plane was?

For example, I'm curious if it would have been closer to the A-20 (Normal: 3-4g; Ultimate: 4.5-6g) or A-26 (Normal: 2.69-4.27g w/ 4.5g listed in passing; Ultimate: 4.04-6.41 w/ 6.75g being the logical result of 4.5g normal rated), or the De Havilland Mosquito (8g @ 18500 lb. IIRC).

 

[GregP]

I liked your post, Niceoldguy58, until the P-61 remark. No way was the P-61 miserably disappointing!

it was the best night fighter available to the USAAF when it came out and for quite some time after that time. Nothing else the USAAF had that was in service anywhere NEAR the service life of the P-61 hit as hard when firing, that's for sure. And it was almost as maneuverable as a single-seat fighter. I've never heard anything bad about the P-61 other than the typical complaints about early radar sets that didn't really get fixed until the 1970s and some comments that it fell a bit short was top speed. But, top speed is NOT all that important for a night fighter to start with. All you have to do is be able to match speed with your target, and the P-61 was faster than any potential target that wasn't a jet.

 

[Zipper730]

GregP

Yeah, the only things I would have seen as being a problem with the P-61 would have been speed, climb, and possibly roll-rate (it was even lower than the F4F)

 

[GrauGeist]

The primary function of night-fighters (during WWII) was to intercept enemy bombers - they didn't need to be dog-fighters.

 

[GregP]

Hi Zipper,

See: https://media.defense.gov/2010/May/26/2001330259/-1/-1/0/AFD-100526-018.pdf

P-61B top speed was 366 mph. Rate of climb was 2,540 fpm (about like a P-40). Service ceiling was 33,100 feet, or high enough for any bombers that were in general use.

P-61C could get to 430 mph.

The 481st Night Fighter Squadron requested Mosquitos. They had a flyoff on 5 Jul 1945. The P-61 was faster at all altitudes, climbed better, and turned better than the Mosquito. It is the only direct flyoff flight test that I can find. It may well have been "tweaked" for best performance but, even if so, the basic airframe had to be decent to perform as it did.

Speed, climb and even roll rate were NOT an issue for the P-61 in WWII, though night fighters after WWII needed to intercept jets. The few jets in WWII were not much of an issue. So, the P-61 eventually DID fall short, as all military airplanes eventually will.

 

[Zipper730]

P-61B top speed was 366 mph. Rate of climb was 2,540 fpm (about like a P-40).

By 1944, the P-40 was largely relegated to the ground-attack mission if I recall. Regardless, that figure might be lower than even the P-47D (prior to the paddle-prop that was added in 1944). I'm curious what the climb-rate of the P-61C was as it's top-speed is quite a bit higher.

The 481st Night Fighter Squadron requested Mosquitos. They had a flyoff on 5 Jul 1945. The P-61 was faster at all altitudes, climbed better, and turned better than the Mosquito. It is the only direct flyoff flight test that I can find.

What P-61 and Mosquito variants were being used?

Regardless, I do remember hearing that the P-61 had a tighter rate of turn than the Mosquito (the stall speed of the Mosquito was around 115 mph vs the P-61's 106 mph), the Mosquito had a faster rate of roll (whether it was consequential or not), with the load factor favoring the P-61 (P-61: 10.95g ultimate; Mosquito: 8.00g ultimate).

 

[GregP]

2,500 fpm for a might fighter is plenty good enough. You didn't dogfight at night, you'd sneak up and make an ambush kill. If the victim ever thought you were stalking him, he'd just maneuver away and get out of sight. Most airplanes flying at night during the war had exhaust flame suppressors on them. Not all, to be sure, but most.

If you go read the link, they don't say which P-61 model was used. I'm assuming a P-61B. They made 200 P-61As, 400 - 450 P-61Bs depending on who you believe, and only 41 P-61Cs.

The P-61 was a good night fighter. It was not an excellent night fighter, but it could perform all manner of aerobatics and could give a single-engine fighter a run for the money in a dogfight, from flight test and mission reports, according to several authors. The P-61C probably qualified as an excellent night fighter because it had more speed than a P-61A/B.

 

[wuzak]

What P-61 and Mosquito variants were being used?

Certainly wasn't the Mk.XXX.

 

[Zipper730]

2,500 fpm for a might fighter is plenty good enough. You didn't dogfight at night, you'd sneak up and make an ambush kill. If the victim ever thought you were stalking him, he'd just maneuver away and get out of sight. Most airplanes flying at night during the war had exhaust flame suppressors on them. Not all, to be sure, but most.

I was just curious because I remember D Dana Bell had stated that F6F night-fighters were swapped in lieu of the P-61's because of their inability to climb to altitude to engage Japanese aircraft. My guess is that this problem was that they lacked the endurance for standing patrols, and couldn't climb fast enough (combined), whereas the F6F at least had a better rate of climb.

I suppose if range was better, it wouldn't be an issue.

The P-61C probably qualified as an excellent night fighter because it had more speed than a P-61A/B.

The -C was a remarkable design.

 

[GregP]

The service ceiling for a P-61B was 33,100 feet. A Ki-46 could get to 35,000 feet and had almost exactly the same speed profile as a P-61. The F6F could get to 37,000 feet and could go perhaps 15 mph faster. So, if you were chasing a Ki-46, the difference between a P-61 and an F6F was slight, indeed. If you add the night fighter radar, the F6F was likely no faster than the P-61, but still had a higher service ceiling.

If you were chasing a Nakajima Ki-84, the Frank could run away from either the P-61 or the F6f, so I'm not to sure why they would choose an F6F over a P-61B in the first place. The Frank was fast, but not usually a threat at night. Curious, indeed.

Cheers.

 

[Shortround6]

let's not forget that "service ceiling" was the altitude at which a plane could still climb at 100ft per minute and that was at standard temperature and pressure. Ceilings in the tropics are going to be lower for everybody.

In theory (on charts) an F6F-3 could climb at almost 500fpm at 33,000ft using "normal power" not military. P-61 has zero hope of intercepting a plane flying higher than it. If the P-61 is climbing it is not flying at max speed. If it is flying max speed at high altitude it is not climbing.

F6F can either try for a pull up shot or try to climb above and dive or just try long range shots in a very slow overtake. Not saying it is easy, just that the F6Fs higher "ceiling" is an indicator of having more options.

 

[Milosh]

Certainly wasn't the Mk.XXX.

Was a MK II iirc.

 

[GregP]

Regarding post #70, stall speed has very little to do with turn rate in combat. And, the calculation formula for turn rate is usually for level turns. I daresay the only combat that will see level turns is combat just above ground level since descending by much would be detrimental to continued flight operations.

Combat turn rate is much more about the maximum lift coefficient and how close to it the pilot can comfortably get without stalling combined with the excess power available over and above the power required for level flight. Since most WWII fighters were supposed to be "the best they could be," maximum lift coefficients were very close to one another. In that case, the combat turn rate was dependent on the stall characteristics of the airplane, including stall warning, the the pilot's airplane feel, and the excess power.

Excess power is not important for instantaneous turn rate, but comes into play after about 60° - 90° of turn (when you hit sustained turn rate), when the airplane has slowed somewhat from the speed it started with and is turning while losing as little speed or perhaps losing no speed if the power is there.

In any discussion of WWII airplanes where excess power is important, the Spitfire has to float to the top due to lightness along with airplanes such as the Bf 109 and some of the lighter Yaks and Lavochkins. The slats on the Bf 109s, though they DID increase the lift coefficient for the slatted area, weren't about turning at all. They were there to keep the airflow attached to the ailerons, and a Bf 109 driver had full aileron control all the way through stall, making it seem like a tight turn, but was really just a controlled stall-turn in some cases when the fighting got down to the stall regime. By "stall," I don't mean slow; I mean when the critical angle of attack was reached or nearly reached.

The Fw 190 had abysmal stall warning (lacked one, in fact) and was not a good airplane around the stall. It could turn well, but only could turn its best if flown by a pilot VERY familiar with the Fw 190. The Fw 190 shared less than wonderful stall characteristics with the P-51 Mustang, and the P-51 was another mount that needed a knowing hand to get maximum turn rate. The Bf 109, on the other hand, had excellent handling characteristics around the stall while simultaneously having some bad characteristics in other regimes of flight where the Fw 190 and P-51 shined brightly.

For Shortround's post #75, I believe the U.S.A. found that bombing from higher than 33,000 feet meant absolutely horrible bombing accuracy, so we stopped bombing from that high and began bombing from lower altitudes so we could hit something. I bet the Japanese found that to be the case, too. There really weren't many bombers that were doing their work from higher than 25,000 feet by anywhere near war's end unless I'm missing something ... so the P-61 would have no trouble getting to and catching the bombers that were in use at the time.

From the data I have, the P-61's AAF combat kill-to-loss ratio was second only to the P-51.

 

[Zipper730]

GregP

1. The issue of the P-61B being faster at all altitudes is a surprise. I thought the Mosquito NF.II's top speed was 366 as well (if Milosh's figures are right). I checked WW2 Aircraft Performance and that's the listed figures for ACA

2. It's a generalized estimate because the maneuvering speed is the velocity where you have enough lift to pull the rated g-load for the aircraft. Regardless, there's other variables such as C/G, and the amount of elevator force to hold the plane in the turn.

 

[Dana Bell]

I liked your post, Niceoldguy58, until the P-61 remark. No way was the P-61 miserably disappointing!

it was the best night fighter available to the USAAF when it came out and for quite some time after that time. Nothing else the USAAF had that was in service anywhere NEAR the service life of the P-61 hit as hard when firing, that's for sure. And it was almost as maneuverable as a single-seat fighter. I've never heard anything bad about the P-61 other than the typical complaints about early radar sets that didn't really get fixed until the 1970s and some comments that it fell a bit short was top speed. But, top speed is NOT all that important for a night fighter to start with. All you have to do is be able to match speed with your target, and the P-61 was faster than any potential target that wasn't a jet.

Hi Greg,

I opened this thread to see what was going on with the XB-42 and was surprised to see mention of the P-61. Sorry to repeat what I've written in several other threads, but here goes...

Actually, the P-61 was miserably disappointing. Being the best available didn't make it good, especially when nothing else was available. Since all of the AAF's eggs were in one basket, there was a concerted effort to convince folks that the basket and eggs actually were pretty good. The P-61 suffered from lack of speed, altitude, and endurance. At one point Wright Field tried to justify continued production by pointing out that Japanese bombers were only slightly faster than the P-61, but that the Japanese would become more confident and slow down to the point the P-61 could catch and destroy them. (That actually did happen on occassion.)

The ETO flyoff was rigged - the Mosquito and its crew were unaware they were in a competition and had been assigned to observe and evaluate the P-61's performance. The P-61 was given the best preparation, flown without the turret or third crewmember, and piloted by an aggressive and angry crew; the Mosquito was a line aircraft of older production with no special servicing. The flyoff was kept below 20,000 feet; above that altitude the P-61's performance dropped off dramatically. The flyoff was flown as a dogfight, not your standard night-fighting tactics. The test lasted only about 2 hours - the P-61 had exhausted nearly all of its fuel.

No P-61 flew at 430 mph - all those claims were based on Northrop estimates, which proved sadly inflated.

The Black Widow's kill-to-loss ratio has no bearing - all those failed attempts at interception never gave the enemy aircraft an opportunity to shoot back.

One AAF squadron was equipped with Mosquito NF.30s and based in Italy at a time when Luftwaffe night activities were fairly limited. In March 1945 a single Ju 188 night raider was targeted by a P-61 which could not intercept and was forced to retire by lack of fuel. A 416 NFS Mosquito then chased the 188 over the Alps to Austria, downing it over its own base before flying back to Italy - all with one of its engines out. No P-61 could have performed as well.

Internal AAF records show the intense disappointment in the P-61, Wright Field's efforts to hide the aircraft's failures, and Hap Arnold's anger when he discovered that the aircraft was not what was promised. Had more Mosquito Mark 30s been available, the P-61 would have been withdrawn from Europe.

Most written histories are little more than propaganda when it comes to the AAF's night fighter designs. The archival records show how disappointing the P-61 really was. What author wants to write a book called The P-61; It Really Sucked, but it was the Best We Had?

Cheers,


Dana

 

[Zipper730]

The ETO flyoff was rigged - the Mosquito and its crew were unaware they were in a competition and had been assigned to observe and evaluate the P-61's performance. The P-61 was given the best preparation, flown without the turret or third crewmember, and piloted by an aggressive and angry crew; the Mosquito was a line aircraft of older production with no special servicing. The flyoff was kept below 20,000 feet; above that altitude the P-61's performance dropped off dramatically. The flyoff was flown as a dogfight, not your standard night-fighting tactics. The test lasted only about 2 hours - the P-61 had exhausted nearly all of its fuel.

Wow, that explains a lot.

No P-61 flew at 430 mph - all those claims were based on Northrop estimates, which proved sadly inflated.

How fast do you think they did fly?