Ki-84 Hei vs TA-152H vs F8F-2 vs P-51H

[GregP]

Wayne, think about what you just said.

On a standard day, the barometer is at 14.7 psi (29.92 " Hg). Then +18 psi boost would be 32.7 psi (14.7 + 18). Gauge pressure. Add another 14.7 for absolute pressure.

But, suppose we are at sea level and the barometer is at 28 " Hg, or 13.77 psig. Then +18 psi boost would be 31.77 psi (13.77 + 18). Gauge pressure. Add another 13.77 for absolute pressure.

On the same day as immediately above (13.77 psi at sea level), the air pressure at 20,000 feet would be around 6.34 psi if the standard pressure drop holds (46.054% of sea level at 20,000 feet), and +18 psi boost would be 24.34 psi (6.34 + 18). Gauge pressure. Add another 6.34 psi for absolute pressure since we ARE at 20,000 feet. The +18 is boost above local ambient pressure, not absolute boost. A supercharger compressor has a pressure ratio, not an absolute output.

But, you know that.

Unless my pixie dust got wet in the rain? Maybe so. Am I crazy? No beer tonight ...

Cheers.

 

[wuzak]

Th USA specified MAP, which does not change with altitude (until the supercharger can no longer provide that pressure, of course).

The British specified the same thing but in different units.

67inHG MAP = +18psi above standard sea level pressure. The V-1650-7 and Merlin 266, which were both built by Packard, could hold this MAP/boost up to ~15-20,000ft.

 

[K5083]

Spiteful? Hornet?

Or more realistically, Vampire or P-80 or 262?

P-51H is the best air-superiority fighter of the group.

And serious high-altitude performance was not all that relevant by 1945 unless you are up against B-29s, which if they were bothered by Ta152H (why not C?) would have flown lower. Because high altitude didn't really work for bombers either.

 

[tomo pauk]

And serious high-altitude performance was not all that relevant by 1945 unless you are up against B-29s, which if they were bothered by Ta152H (why not C?) would have flown lower. Because high altitude didn't really work for bombers either.

Escorts were also flying at high altitude, a tad over bombers' flying altitude. Lack of performance at altitude was a big factor in Luftwaffe's demise in 1944, whose Fw 190s, Bf 109s and whatnot were trashed even above Germany proper by P-51s.

 

[GregP]

Changes with atmospheric pressure changes, though. As altitude increases, atmospheric pressure drops off, and the supercharger can only maintain sea level power until it reaches its limit. AT 18,000 feet or so, you have half the sea level pressure. S

Suppose we start at 14.7 psi at sea level. Then we have about 7.35 psi at 18,000 feet or so and the supercharger needs to supply the other 7.35 psi of boost to get sea level power. Many WWII superchargers could do that. But the early single-stage units started to fall off pretty much above 15,000 - 18,000 feet. That's because they weren't used exclusively for turbo-normalizing, they also ran boost at sea level to increase the power output to the propeller. So, they ran out of boost earlier than if they had been used only for turbonormalizing.

All MAP means is Manifold Absolute Pressure as opposed to gauge pressure. You could set the MAP and the automatic controller would try to keep that MAP all the way up, and it did until the supercharger reached its boost limit. But if you use only 6 psi of boost manually, the MAP will change with altitude as the atmospheric pressure changes. To stay constant, it requires an automatic pressure regulation controller or manual pilot intervention.

 

[wuzak]

Changes with atmospheric pressure changes, though. As altitude increases, atmospheric pressure drops off, and the supercharger can only maintain sea level power until it reaches its limit. AT 18,000 feet or so, you have half the sea level pressure.

Engines such as the Merlin used throttles to maintain boost pressure at the desired level. As the altitude increases the throttle is opened to maintain the boost pressure (or MAP). Because of the losses of the throttling system, the power increases with altitude.

When the throttle is fully open and the altitude increases the boost (and power) falls away.
This chart shows that the Merlin 66 could maintain +18psi boost to just shy of 10,000ft, after which boost (and power) falls until the high gear is engage, and +18psi boost is maintained to 20,000ft.

http://www.spitfireperformance.com/merlin66hpchart.jpg

This report about the P-51D, with Packard V-1650-7, shows a critical altitude (the point at which the throttle is fully open) for the aircraft to be 11,300ft in Low gear and 24,300ft in high gear at 67inHg MAP.

P-51D Performance

67inHg MAP = 18psi above standard sea level pressure.

That is to say, the British were measuring MAP and describing it as boost above sea level pressure.

Suppose we start at 14.7 psi at sea level. Then we have about 7.35 psi at 18,000 feet or so and the supercharger needs to supply the other 7.35 psi of boost to get sea level power. Many WWII superchargers could do that. But the early single-stage units started to fall off pretty much above 15,000 - 18,000 feet. That's because they weren't used exclusively for turbo-normalizing, they also ran boost at sea level to increase the power output to the propeller. So, they ran out of boost earlier than if they had been used only for turbonormalizing.

Only turbos were used for turbonormalising. Mechanical superchargers were used for boosting performance, particulalry at altitude.

All MAP means is Manifold Absolute Pressure as opposed to gauge pressure. You could set the MAP and the automatic controller would try to keep that MAP all the way up, and it did until the supercharger reached its boost limit. But if you use only 6 psi of boost manually, the MAP will change with altitude as the atmospheric pressure changes. To stay constant, it requires an automatic pressure regulation controller or manual pilot intervention.

The Merlin did have an automatic boost control that controlled the throttles as altitude increased. As I understand it, some US engines did not have that feature, such as the V-1710.

 

[GregP]

That's a nice graph, Wayne but, like ALL engine graphs, it is what you would expect of the test engine on a standard day. Take the same engine from a standard day with the temperature at +25 over standard and the chart will surly change. Same if you test the same engine on a low-pressure day. Add up a low-pressure day and hotter than standard temperatures, and the power drops off considerably.

Ask anyone who has flown on a cool, high-pressure day and then on a warm, low-pressure day, especially in something as power sensitive as a Cessna 172. But if affects planes like the mighty F-15 Eagle the same way. There's just not as much drop off noticeable when you are flying a high-performance aircraft.

Hence, all the accidents on high and hot operations.

 

[JDCAVE]

Why is everyone so head-over-heels with the TA-152? It wasn't operational during the war. It had zero impact.

 

[GregP]

Actually, it WAS operational. Just not for very long nor very successfully.

The Ta 152's used in WWII were basically a short run of prototypes that were called "production." There was no logistics chain of spares so, when a Ta 152 went "down," it became a source of spare parts for still-operational airplanes. They built about 150 Ta 152s, completed 67 H-0, H-1, and C-1 airframes, and delivered 43 to operational units.

The Ta 152 was rushed into service in January 1945, before all the normal development issues were sorted out. Deteriorating war conditions meant that Ta 152 was released into combat right when the Allies were sending over 500+ bomber raids escorted by 300+ fighters. As a result, in total, the Ta 152 amassed anywhere from 7 - 10 victories against 4 losses. That's pretty mediocre in anybody's book, but it was not entirely the Ta 152's fault. The war situation meant that any airborne German fighter was a target for many Allied fighters. It basically started to see normal operations in April 1945, right when the Luftwaffe collapsed as a fighting force. When the war ended for Germany, there were exactly two Ta 152Cs left flyable. That isn't going to get much fighting accomplished, even in the hands of experts.

Most Ta 152 pilots received about 20 minutes of flight time before being assigned to their units. Hardly a recipe for success, but in keeping with the wartime situation. Had it been introduced a year earlier, it might very well have seen considerable success. Wish one or more were still flyable.

 

[tomo pauk]

Why is everyone so head-over-heels with the TA-152? It wasn't operational during the war. It had zero impact.

It was more operational than P-51H, let alone the F8F-2.

 

[GregP]

True, Tomo, but neither of the two U.S. airplanes you mentioned were rushed into service before being debugged. When they got to where they were deployed, they were ready to fight, and had spare parts provisioned and trained support personnel ready to service them. They weren't prototypes that were sent out for desperate combat when the war situation was just about done. They were ready for front-line service. There just weren't many airborne enemy targets in the last 2 weeks of WWII around Japan.

The Ta 152 is one of my favorite aircraft of the war, but it just wasn't very effective "as deployed." "As deployed" just means the way it was actually used during WWII. That doesn't mean it would not have been a great warplane. In all likelihood, could have been. All it means is the Ta 152 wasn't ready for the things it was tasked with when it was tasked with them, and neither were the logistics chain, the maintenance personnel, or ... really,... the pilots since they weren't very familiar with the airplane, which was considerably different from a radial-engine Fw 190 or even the Fw 190D family. It had two engine boost systems that were supposed to be used in different circumstances, different systems, and wildly different airspeeds that were best for particular maneuvers. A long wing does not perform maneuvers anywhere near the same as a short wing.

I don't blame the Germans for deploying it. In desperate situations, desperate measures are indicated. It just didn't have much effect as the Reich was crumbling, and not entirely unexpectedly so.

The Bearcats, P-51Hs, and Tigercats were good airplanes that didn't get much of a chance at war during WWII. But NOBODY would have wanted to prolong the war just to try out new airplanes. With the end of the war, the large production orders were cancelled and they really didn't make many of any of them. That was a direct result of the end of the war and the beginning of the jet age. It wasn't a reflection of the potential of any of the three airplanes. I'm sure that had the war in Europe continued for another year, the Ta 152 would have been a major player. In the real world, it just wasn't.

 

[dedalos]

Ta152H-0,-1 were not prototypes. They were initial production machines. They lacked many of the intented equipment(gm1,mw50,engine gap seal, etc) but that was because of the war situation
They demonstrated excellent handling , agility and climbing better than the earlier Fw s on similar horsepower, but with the Jumo 213E could not follow Late war s allied fighters
P51 H had the support of world s greatest industrial country, full development cycle , and still was nwver deployed to combat. The earlier D version was sent instead. That means a lot
We dont know enough about the ki84. We do know it was light, low wing loading, 2000 hp from a very small diameter radial engine, beautiful handling. If built with quality should have performance and agility very similar with the F8F1

 

[JDCAVE]

It was more operational than P-51H, let alone the F8F-2.

But not the P51 marks overall.

At various stages in the war, the various marks of the Me.109, FW.190, Me.262, Spitfire, P.47, P.51, all had significant impact on the air war in Europe. At times they all had certain local dominance and had a major contribution. The TA.152 did not, at any stage.

 

[tomo pauk]

But not the P51 marks overall.

At various stages in the war, the various marks of the Me.109, FW.190, Me.262, Spitfire, P.47, P.51, all had significant impact on the air war in Europe. At times they all had certain local dominance and had a major contribution. The TA.152 did not, at any stage.

Please note that thread is specifically about the 4 listed fighters, including the Ta-152. It is not about Spitfire, Fw 190, Me 262 etc.

P-51H was all-new aircraft vs. P-51s that saw combat. Ta-152 at least shared fuselage, cockpit and tail with Fw 190.

 

[SaparotRob]

As someone (someones?) said before, the RAF and the USAAF had no reason to rush aircraft into production until all the bugs were worked out. The LW, not so much.

 

[GregP]

Hi Dedalos. Yes, they WERE prototypes. They had no real "production completion standard," and items were being added / dropped / changed constantly. There were no spare parts. There were no "factory-trained" mechanics. They relied on people who had worked on Fw 190D models and radial-engine models, even though the Ta 152s were considerably different from the Fw 190D models.

Heck, the Luftwaffe had more Bf 109 and Ju 88 prototypes than they had total delivered Ta 152s.

What else do you call an airplane where there are no spare parts, every delivered plane is slightly different from the last one, and total so-called production was under 50? I call it a prototype. They may have had jigs for various fuselage parts because the longer fuselage just had extensions added, but I'd bet they only had one or two sets of jigs for the long wings. If they had more, then more would have been delivered.

But, hey, it's terminology. At this point, all we really need to agree on is the Ta 152 made no impact to the war effort. Even if we don't agree, it didn't affect the war at all except to take up resources. Altogether a waste of effort, though it WAS impressive as an aircraft, from a performance point of view. I think that with development, it would have been even better. Alas, it never happened.

 

[dedalos]

Hi Dedalos. Yes, they WERE prototypes. They had no real "production completion standard," and items were being added / dropped / changed constantly. There were no spare parts. There were no "factory-trained" mechanics. They relied on people who had worked on Fw 190D models and radial-engine models, even though the Ta 152s were considerably different from the Fw 190D models.

Heck, the Luftwaffe had more Bf 109 and Ju 88 prototypes than they had total delivered Ta 152s.

What else do you call an airplane where there are no spare parts, every delivered plane is slightly different from the last one, and total so-called production was under 50? I call it a prototype. They may have had jigs for various fuselage parts because the longer fuselage just had extensions added, but I'd bet they only had one or two sets of jigs for the long wings. If they had more, then more would have been delivered.

But, hey, it's terminology. At this point, all we really need to agree on is the Ta 152 made no impact to the war effort. Even if we don't agree, it didn't affect the war at all except to take up resources. Altogether a waste of effort, though it WAS impressive as an aircraft, from a performance point of view. I think that with development, it would have been even better. Alas, it never happened.

Its not important what i call them . The manufacturer called them initial production machines.
In hermann s book , he provides with serial numbers , the description of all produced aircraft. And yes all the h-0 s were similar , and almost all the h-1 s were the same, although as i said they did miss important
equipment
Look, personally i am very skeptical about the design of the Ta 152. But it s not the design s fault that no raw material s for its engine were available and no c3 fuel .
And the fact that was able to dogfight , without mw50, tempests and yak 9s at low altitude, despite its huge wings, was noteworthy.
At the same despite the lack of mw50 and gm1, and its heavy armor and armament , and poor quality surfaces was pretty close in performance with spitfur xix, a recce version

 

[GregP]

I agree, it's not important what we call them.

The design, to me, was a very good one. Raw materials, labor, transport, fuel, propellers, etc. were very hard to come by when you were being bombed day and night, and the fact Focke Wulf made as many as they did under late wartime conditions was noteworthy. Nothing wrong with the airplane that a major change in the wartime situation would not have mitigated and made better. Under the right circumstances, the Ta 152 could have been a great airplane. To me, it was anyway. It wasn't much of a factor in the war, but was a sparkling aviation achievement in design stretch-development under harsh conditions.

Let me say it this way, nobody who was a fighter pilot would have turned down a Ta 152 (C or H) if everything on the airplane was working properly. It was a winner is every way but when employed right as the air force was crushed as a fighting force, as the Luftwaffe was in April 1945. Then again, NO new airplane would have turned out very well under those circumstances. The Ta 152 did OK, given the situation it found itself deployed in.

 

[wuzak]

Wasn't -0 a pre-production model, while -1, -2, etc, were production models?

So a Ta 152H-0 was pre-production, but Ta 152H-1 was the production model?

The prototype Ta 152H was the Fw 190 V30?

 

[GregP]

They called them "production" models, but they really built a run of prototypes. Real production implies a standard build configuration, spare parts for logistics, training for mechanics, training for pilots, a standard tool set for the aircraft, standard maintenance stands and tools for things like engine changes, propeller changes, replacing wings, jacking for C.G. measurements, hoists for gun changes, etc. All the things needed to support the aircraft.

What Focke-Wulf did was to build a run of Ta 152 airframes, finish a few, and send them out to Fw 190 units knowing they would do the best they could with whatever they had, and trusting that the Ta 152 was similar enough to the Fw 190D models to be maintained by the existing personnel. Considering the wartime situation, that was perhaps not an unreasonable thing to do but, at any OTHER time, the Ta 152 as-built would never have been released for service test at that time. The units were a service test units anyway, and were supposed to work up the combat employment syllabus, but wound up being the first and last to operate the airplane, with almost all of them going unserviceable before war's end.

Again, a not entirely unexpected result. They likely didn't think it would happen in April 1945, but it did, and the Ta 152 operated from January 1942 to April 1945. Not a really significant service life, and the Ta 152s never got to fight the high-altitude fight they were designed for. But, fight, they did.

Our own P-51Hs, F4U-4s, and F7Fs made it into the war and flew missions ... likely more missions than the Ta 152s ... an assumption on my part, perhaps incorrect in reality. But, they never encountered any Japanese Military aircraft and thus never saw air-to-air combat during WWII. That said, they still made the war as active service aircraft. I do not claim any combat prowess for them based on WWII results, but they showed themselves to be formidable aircraft when they were flown in regular service. Likewise the Hawker Sea Fury and Spitefuls / Sefangs / Sea Hornets / La-9s / La-11s.

Pretty good airplanes, one and all, including the Ta 152H. It just had a very short, difficult service life operating from what turned into primitive airfields due to bomb /strafing damage.