Aircraft Modifications

However, the first flight was delayed by problems with the experimental Continental engines, which were not yet cleared for flight operations at the time they were delivered to Lockheed in April 1942. It was not until November 14, 1942 that the XP-49 took to the air for the first time, flown by test pilot Joe Towle.

The aircraft was grounded only a week later for replacement of the engines by XIV-1430-13/15 engines

The initial flight tests of the XP-67 were delayed by fires in BOTH engines that broke out during a high-speed taxiing run at Lambert Field in St Louis on December 8, 1943. After being repaired, the XP-67 was trucked to Scott Field in Illinois. The first flight of the XP-67 took place there on January 6, 1944 with test pilot E. E. Elliott at the controls. However, this flight had to be abruptly terminated after only six minutes owing to engine problems.

This accident, plus the seemingly endless series of problems caused by the temperamental Continental engines, caused the USAAF to recommend that work on the XP-67 project be halted.

Estimated power of the IV-1430 in the P-67 was 1060hp from its hoped for 1350hp(G. White). The bugs were worked out? Does not look that way.

The Muskegon plant also built P&W R-1340s.

KraziKanuK said:

However, the first flight was delayed by problems with the experimental Continental engines, which were not yet cleared for flight operations at the time they were delivered to Lockheed in April 1942. It was not until November 14, 1942 that the XP-49 took to the air for the first time, flown by test pilot Joe Towle.

The aircraft was grounded only a week later for replacement of the engines by XIV-1430-13/15 engines

The initial flight tests of the XP-67 were delayed by fires in BOTH engines that broke out during a high-speed taxiing run at Lambert Field in St Louis on December 8, 1943. After being repaired, the XP-67 was trucked to Scott Field in Illinois. The first flight of the XP-67 took place there on January 6, 1944 with test pilot E. E. Elliott at the controls. However, this flight had to be abruptly terminated after only six minutes owing to engine problems.

This accident, plus the seemingly endless series of problems caused by the temperamental Continental engines, caused the USAAF to recommend that work on the XP-67 project be halted.

Estimated power of the IV-1430 in the P-67 was 1060hp from its hoped for 1350hp(G. White). The bugs were worked out? Does not look that way.

The Muskegon plant also built P&W R-1340s.

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I've never seen that info. Perhaps you are right.

Only about 35 of the hyper-engines were built, none were "production" engines.

And the 'hyper-engine' projects ate up countless valuable hours of manpower without producing a single, combat-capable engine. One of the great flops in the history of the American aviation history if you ask me.

Lightning Guy said:

And the 'hyper-engine' projects ate up countless valuable hours of manpower without producing a single, combat-capable engine. One of the great flops in the history of the American aviation history if you ask me.

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Umm... it ate up relatively few hours, mostly prior to the war. There were lots of such projects on all sides. The Bristol Centaraus project comes to mind as one of the biggest failed engine projects of the war. Far far more resources were spent on it than the hyper-engine, to produce a very few working bombers and left a few hundred Tempest II's sitting w/o a powerplant till after the war was over.

Had the hyper-engine recieved substantial attention, it probably would have worked fine. Instead, it recieved minimal focus, being relegated to a single rather minor project which was botched in many respects, not just the engine development.

=S=

Lunatic

But the Centaraus did become a viable engine. And the Sea Fury with a Centaraus engine was one of the best piston-engined fighters of all time.

Lightning Guy said:

But the Centaraus did become a viable engine. And the Sea Fury with a Centaraus engine was one of the best piston-engined fighters of all time.

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So would have the hyper engine, if the need to further develop inline aircraft engine had persisted. It did not, by the time the bugs were worked out of the Centaraus, the jet age had arrived. By the time the SeaFury was deployed, it was already totally out-of-date.

Bristol did not have the engineering staff to properly develope the Centaurus. When Bristol's directors fired Roy Feldon in Oct 1942, the Centaurus engine took a big hit. Bristol did manage to poduce 2800 engines though befor wars end.

LightningGuy, the hypers were not a waste of time for much was learned from them.

Maybe. But in time of war I feel your limited time and resources are better spent producing what works.

Lightning Guy said:

Maybe. But in time of war I feel your limited time and resources are better spent producing what works.

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Well of course, but that is easy to say with 20:20 hindsight. All sides spent significant resources working on projects that did not work.

KraziKanuK said:

Bristol did not have the engineering staff to properly develope the Centaurus. When Bristol's directors fired Roy Feldon in Oct 1942, the Centaurus engine took a big hit. Bristol did manage to poduce 2800 engines though befor wars end.

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The Centaraus engines were not really buildable until Bristol got a Thompson centerless grinder. I believe what happened was the required tolerance of 1/10000 of an inch for the sleeve valves was too tight for prior machine tools to properly fabricate. This resulted in very high oil consumption and poor cylinder unit durability until post war. The three of the Thompson centerless grinders provided to Britain during the war all went to the Napier Saber project. The Centaraurs engines that were produced were suitable only for bombers, such as the Warwick, which could carry a lot of oil. This is why several hundred completed Tempest II's, with installed Centaraus engines, were never deployed to combat units. They simply could not carry enough extra oil to make them safe for combat.

Do you mean Bristol engines including the Hercules? I only know of about 4-500 wartime Centaraurs engines.

KraziKanuK said:

Anyone know why the Allison V-3420 when fitted to the B-29 (YB-39), even though gave the a/c better performance, were not used?

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The XB-39 with the V-3420 wasnt produced mainly because most of the problems with the R-3350 had been worked out.

The performance difference was only marginal. The V-3420 gave 3000 hp on takeoff but only had 2100 hp at 25,000 ft. It had an integral single stage single speed supercharger plus this was fed by a single turbocharger. The R-3350 on the other hand had an integral single stage single speed supercharger plus two turbochargers. This enabled the R-3350 to maintain its rated 2200 hp to around 30,000 ft. The R-3350 was also able to make some of its War Emergency power at this altitude as well. Later fuel injected R-3350's that employed newer turbochargers could certainly make more power at 30,000 ft plus. I have talked to many who have said late war R-3350's were underrated, meaning they were making more power than advertised. Some have said these late R-3350's in War Emergency power were making close to what later R-4360 made at takeoff. That equals out to around 3500 hp. I dont know whether thats true or not but I'll take their word on it, they were there!

The performance of the XB-39 was listed as 405 mph at 35,000 ft. This isnt exactly comparing apples to apples though. The XB-39 was converted from the first YB-29. Even though it was equipped with full armament it can be safe to say that this aircraft didnt weigh nearly as much as a like armed B-29 in the Pacific. It almost certainly didnt have a lot of the armor plating, electronics, radar and some safety equipment that a standard B-29 would carry.

Another thing that should be considered is the propellers. The XB-39 was equipped with Curtiss Electric units that have a broader chord than the Hamilton Standard units found on most B-29s. This can be compared to the performance increase at altitude found between the B-17E and B-17F due to the paddle blade propellers. The F was heavier yet at the same power rating had a higher service ceiling and was faster at its ceiling.

A truer comparison perhaps would be to compare the XB-39 to the Silverplate B-29's of the 509th Composite Group. The Silverplates were stripped of turrets but did carry a full suite of electronics, radar and safety equipment. Silverplates also were equipped with the latest fuel injected R-3350's turning broader chord Curtiss Electric reversible pitch propellers. These were truly the finest B-29's that could be found in the Pacific. They were able to climb higher and fly faster than standard B-29's. During the Nagasaki mission at one time Bockscar flew over 39,000 ft fully loaded. In talking with 509th veterans, a few pilots, flight engineers and a couple NCO's, they have said during their practice pumpkin missions that coming out of their steep turn and running away that they frequently got over 400 mph. The aircraft at the time would have been unloaded and in its already light condition plus the Curtiss Electric props and being at War Emergency power I see this as being extremely possible. Like before, they were there!

A B-36 Peacemaker with extra guns and extra power, and depending on when we are talking about anti-aircraft missiles and cluster-bombs. That would really have an impact on an opposition pilot, something like that.

The B-36 is clearly a post WWII design. I think this topic is restricted to WWII technology and planes.

(note: edited "P-36" to "B-36")

RG_Lunatic said:

The B-36 is clearly a post WWII design. I think this topic is restricted to WWII technology and planes.

(note: edited "P-36" to "B-36")

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I'll try to find the reference but the B-36 design was begun in WWII. The fear was that bombing missions may have to be based on the East Coast of the US. The B-36 was to make that not only possible but more or less practicle.

Requests for preliminary designs for a bomber capable of 450mph top speed, 275mph cruise, 45000' ceiling, and max range of 12000 miles at 25000' carrying 10000lbs were issued to Boeing and Consolidated on April 11, 1941. And on November 15, 1941 a contract was issued to Consolidated to provide two XB-36's.

but it was soon realised that we could hold Britian (you don't show much faith in us, do you??) and the B-36 wouldn't be needed really so it didn't become much of a priority.............

A B-17 with side firing heavy gun plus a couple of light machine guns for close combat support like the AC-130 Hercules does for US troops today. Would have helped at Tarawa, Omaha, Iwo Jima and a few other places by acting as aerial artillery against bunkers and things...

HealzDevo said:

A B-17 with side firing heavy gun plus a couple of light machine guns for close combat support like the AC-130 Hercules does for US troops today. Would have helped at Tarawa, Omaha, Iwo Jima and a few other places by acting as aerial artillery against bunkers and things...

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It wouldn't of worked - they had no accurate way to target it.

What aiming devices did the succesful AC-47 have?



Kris

Also I dont think the aircraft would have been wide eneogh to incorporate the larger guns. I may be wrong though.