Mistakes in Aviation

[kool kitty89]

Yes, and the Goblin was better used for the Vampire as well. (it was probably good that DH kept their Goblins, save for those sent to the XP-80 project) If there'd been more intrest the Vampire by the Air ministry it may have seen servise sooner.

The Vampire was a better design IMO as it could do more with less thrust/weight and was all-around better in terms of practicality and performance. Of course, the Meteor would have been 2 years ahead in development if it weren't for Rover...

Both England and Germany made some stupid mistakes like that with their jet programs. (ie canceling Heinkels class I engines)
On the other hand the US jet program went rather smoothly, albeit more than 2 years late in the game and getting a head start with Whittle's design. However, if we look a little further back we can see that the US made on of the BIGGEST mistakes of all: somewhat like the Soviets, the US had a number of jet/rocket reasearch project in the 1930's, in particular a NACA program which progressed to about 1939 and then was abandoned as "impractical." Another jet/rocket program was also started, but focused primarily with small designs for RATO/JATO. And thus the US lost any chance at getting into the feild nearly as early as others. In fact the NACA was still favoring ducted fan/motorjet designs with the new development projram in 1941. (the only real development from this program was with Westinghouse and Became the J30, the first all American turbojet engine to run, and also one of the best performing engines of the War with excelent thrust for its size: 1600 lbf at 19 in diameter and under 700 lbs weight)

 

[maut9r]

One of the biggest errors in the US effort was never getting Merlin's in the P-38. Several groups of Merlin P-38's sure could have helped things out over Europe until the P-51B arrived.

 

[kool kitty89]

What do merlins have to do with anything?

The problems were with the engine occling system, sometimes becoming overeffective or with radiator flaps jamming. (the overcooling caused the coolant and oil to circulate too slowly and the engine could overheat or seize)

There were also problems with the cocpit heatin. (lack therof) And problems with the intercoolers (inside the outer wings' leading edge) being inadequate and vulenerable.
Then there's the compressibility problems at .68 mach... But a good pilot could avoid these and even dive after an enemy if he kept speed well regulated. (throttle back) The dive flaps solved this but still limited speed to .68 mach.
Roll rate was also mediocre, and poor at high speed.

Most of these problems were solved with the P-38J and all the improvements
were present in the late production J models, including dive flaps and boosted ailerons. (with compeditive roll at low-medium speeds and excelent roll at high speed)

 

[FLYBOYJ]

One of the biggest errors in the US effort was never getting Merlin's in the P-38. Several groups of Merlin P-38's sure could have helped things out over Europe until the P-51B arrived.

A myth....

The fact remains the brass in the ETO did not like the P-38 and Merlins or not it wouldn't of changed things much....

 

[Freebird]

One of the biggest errors in the US effort was never getting Merlin's in the P-38. Several groups of Merlin P-38's sure could have helped things out over Europe until the P-51B arrived.

No, the mistake was foolin' around with the prototype in a PR stunt and crashing it before proper tests could be done, set the program back at least a year....

 

[V-1710]

A myth....

The fact remains the brass in the ETO did not like the P-38 and Merlins or not it wouldn't of changed things much....

I agree. the Merlin would not have add much if anything to the P-38's performance. In other aircraft, the advantage the Merlin had over the Allison was it's 2 stage supercharger. Since the Allisons in the P-38 were turbocharged (as the Allison was designed for), they didn't suffer from poor high altitude performance as the single stage Allison did in the P-39 or P-40, for example.

 

[V-1710]

I think the Luftwaffe should have incouraged development of the He. 277. The He. 177 was a fine airframe rendered nearly useless by poor engines.

 

[kool kitty89]

The 177 also had a lot of extra weight needed for the dive bomber requirement, granted this gave it a very strong airframe, but it limited performance, range, and load capacity.

Similar things limited the Ju 88's ability as a fast bomber. (originally a max sustained speed of 320 mph was obtainable on the V5 with standard 3-gun armament and 2000 kg payload, top speed of the unarmed V1 prototype was ~360 mph, iirc this was with 900 ps DB 600 engines) Additions for dive bombing and other RLM pet projects limited it to ~280 mph on production models when loaded. (and ~300-320 top speed after dropping bombs)

The other additions also slowed development and deployment somewhat.

 

[model299]

I'm assuming we can talk about any era. If not, let me know and I'll pull this post.

Say what you will about the politics of the move, nearly fifty years after the fact, the abrupt decision to cancel the Avro Canada CF-105 Arrow remains hotly controversial to this day in Canada.

By all reports, it was a superb aircraft for its class with tremendous potential.

 

[HoHun]

Hi Don,

>FW 187 1942 calculated:
>engines: two Daimler-Benz DB 601A each with 1.100 PS

>FW 187 1943 calculated:
>engines: two Daimler-Benz DB 605A each with 1.475 PS

Interesting concept! Below some quick calculations I prepared from data in Hermann/Petrick's "Focke Wulf Fw 187".

My version of the DB601A-1 engined Fw 187 is powered by the early variant of this engine, which had a 4 km full throttle height. The improved version with 4.5 km already saw use in the Battle of Britain and would have given slightly better speed, and probably have been more accurate for the 1942 data point you're interested in. I really chose the older engine for convenience reasons only My speed curve is based on the drag of the V-4, which was the A-0 series prototype. You'd probably have to add some drag for larger radiators, so it's a slightly optimistic curve. I chose 5500 kg as reference weight, slightly less than your 6000 kg.

The Fw 187C is also called Fw 187 Kampfzerstörer or Fw 187 neu, and it is calculated for 6620 kg mean flying weight with no external bombs, but external bomb carriers in place. It's not powered by the DB605A but by the DB605A-C with a different propeller reduction gear so that it can use 3.4 m diameter propellers. It also has a slightly different wing (span/area) according to the data in the book I'm using. The speed data is for 1.3 ata/2600 rpm, with the 1.42 ata/2800 rpm setting the speed obviously would be somewhat higher. The drag of the Kampfzerstörer is up quite a bit and the external bomb carriers probably play a role in that, as well as the enlarged canopy. With the drag of the V-4, it would have achieved more than 720 km/h according to my estimate.

Regards,

Henning (HoHun)

 

[maut9r]

Glad to see you guys don't take it easy on the newbie!

I agree the PR stunt on the XP-38 was a huge blow to the program. Cockpit heat was awful at best as well and the P-38 didn't seem to be well liked in ETO, but was that because of all the engine problems? Did the P-38 have the same problems in other theaters too with overcooling? (I don't know just furthering the discussion) I still think that a more dependable engine package would have done a lot to improve the P-38 in Europe and maybe a passable escort fighter earlier than the Merlin Mustangs. But then that would have had to start this development pretty early in the war or before, at which time no one knew of the problems in Europe........Hmm I seem to have talked myself out of my answer!


Model299 good call on the CF-105! If you want to get a Canadian fired up quickly mention that plane. A potentally great plane that died from pretty sketchy causes!

 

[kool kitty89]

The overcooling problems (along with heating) were not much of a problem in the warmer PTO and MTO where they were more sucessful, plus these tended to take place at medium altitude, lessening the temperature problems further and reducing the compressibility problems. (speed of sound higher in denser air at low alt, plus the speed in general was lower at low alt)

I don't know a whole lot on this, but I think the P-38 did better in N. Africa as well.

 

[HoHun]

Hi Koolkitty,

>The overcooling problems (along with heating) were not much of a problem in the warmer PTO and MTO where they were more sucessful

Hm, I think it was Clay Tice who told me that his unit (flying P-38s) never managed to intercept the Dinah reconnaissance aircraft that overflew their bases because they had to level-off every now and then during a high-performance climb to avoid overheating their engines.

>plus these tended to take place at medium altitude, lessening the temperature problems further and reducing the compressibility problems. (speed of sound higher in denser air at low alt, plus the speed in general was lower at low alt)

Generally correct, but from PTO P-38 pilot MF Kirby I heard that they would never follow a Japanese fighter in a split-S because the risk of overspeeding when trying to follow with the P-38 was considered too high. Apparently, the split-S was not a common manoeuvre for the Japanese pilots either, perhaps because of similar concerns for overspeeding, but Kirby remarked that they could have evaded the attacking P-38s more easily if they had known of its restriction.

Regards,

Henning (HoHun)

 

[HoHun]

Hi again,

>Below some quick calculations I prepared from data in Hermann/Petrick's "Focke Wulf Fw 187".

Here some photographs of the Fw 187 model in the Luftfahrtmuseum Hannover-Laatzen ...

(I'm going to post them separately to avoid the display problem for Opera users described here.)


Regards,

Henning (HoHun)

 

[HoHun]

#2

 

[HoHun]

#3

 

[DerAdlerIstGelandet]

Nice model. How large is it?

 

[renrich]

This has been discussed in other threads but in my opinion the War Department of the US in 1940, when the XF4U became the first single engined fighter in the US to exceed 400 mph in level flight, should have: (1) Canceled the P47 and P38 programs and told Republic and Lockheed to take the Corsair design and adapt it for use by the AAF. (2) Phased out the P39 and P40 programs. (3) Continued the development of the P51 by North American and told Curtis to assist.(4) Told Grumman to collaborate with Vought to build Corsairs for the USN and Marines and cancel the work on the Hellcat. (5) Cancel the Curtis program on the Helldiver and make the Corsair the dive bomber to replace the Dauntless. The US would have wound up with two fighters eventually, the F4U and P51. With the mixture of ideas and resources of several companies developing and manufacturing the two different models, the advanced models of both AC would have come online much faster and the costs of the two AC would have dropped considerably. Concentrating on only two fighter engines would have had large benefits in manufacturing and in maintenance.

 

[kool kitty89]

At that time the P-51 was still a paper design and needed alot of work, plus it took a complicated chain of events to result in the P-51
being powered by the Merlin 60 series engine and being accepted as an escort fighter by the USAAF.

Initially the AAF hadn't liked the Mustang early on one reason being that it was an independant company design, not ordered into development
by the AAF.

(as a land based fighter, carrier operations asside)
And why is the P-47 worse than the F4U? The Corsair could turn and climb a bit better below 20,000 ft, but that's about it. Comparing the early
paddle bladed P-47D to the F4U-1, the F4U would have an advantage up to 20,000 ft, the P-47 above 25,000 ft. The P-47 had better foreward
vivability, and all-around with bubble-top. Both were tough, with an edge to the P-47 due to the F4U's oil coolers, and to a lesser extent the
partial fabric and wood construction. (which did have some advantages)

Or by the same logic, why build the P-51 at all, it had a bit of a speed advantage over the F4U-1 (less in the P-51D), but that was about it,
both hat critical altitudes of ~24,000 ft. Again the P-51 had better visibility. Their range/radius was about the same with the F4U's LE wing
tanks. And since the longer ranges were necessary the wing tanks wouldn't be eliminated as they'd been on later Navy F4U's. They might have
even been fitted with self sealing instead of just the CO2 pressurization for fire supression.


The P-38 had some development problems, excess cost and with hindsight didn't have significant advantages to merit it, the P-47 and F4U being
capable multi-role a/c. The P-38 was introduced earlier, but still ad alot of problems, less so in the PTO. It was a good a/c though.

Despite the F4U first flying almost a year before the P-47 it didn't enter service until after the P-47.


And since there was a much larger infrustructure for the V-1710 already in place, why not just build a turbocharged P-51? The main reason this
wasn't encorporated into the original design was that the British hadn't wanted it. And it was simpler to convert the existing design to the Merlin
than to add a turbocharger. (probably in a ventral position similar to the P-47)


Of course, in any case focusing on a single new design isn't wise, there should always be a couple competing designs in case one fails.

 

[FLYBOYJ]

The P-38 had some development problems, excess cost and with hindsight didn't have significant advantages to merit it, the P-47 and F4U being capable multi-role a/c. The P-38 was introduced earlier, but still ad alot of problems, less so in the PTO. It was a good a/c though.

You're very wrong! The P-38 WAS a very good multi role aircraft - 1000 pounds of bombs or rockets easily - while the advantage of the radial engine is apparent, the P-38 was a true multi role aircraft - Droop Snoot, night fighter and recon aircraft, the only thing it really had going against it were "single engine fighter pilots" who couldn't handle a little extra work and some brass in the ETO who preferred Mustangs...