Hardest plane to take down in WW2? (1 Viewer)

[renrich]

Lindberg conducted classes with many pilots on several types of AC about fuel conservation. I recall reading he told them to forget about much of the stuff they had learned about babying their engines because they were military engines and could take a lot of abuse. He did all this including combat flying while acting as a civilian consultant.

 

[FLYBOYJ]

Lindberg conducted classes with many pilots on several types of AC about fuel conservation. I recall reading he told them to forget about much of the stuff they had learned about babying their engines because they were military engines and could take a lot of abuse. He did all this including combat flying while acting as a civilian consultant.

Correct.

In actuality "exceeding the chart" could be done in almost any recip aircraft. A lot of times the data is there, it's just a matter of the way it is formatted on a particular chart and the parameters given.

 

[HoHun]

Hi Flyboyj,

>Lindbergh explained cruise control techniques he had worked out for the Lightnings: reduce the standard 2,200 rpm to 1,600, set fuel mixtures to "auto-lean," and slightly increase manifold pressures.

Certainly - but my impression is that he was able to do that was more the result of the original USAAF "matched power settings" not having been optimized for range beforehand. His strategy matches the procedure the British had established before. (I don't know the V-1710 specific fuel consumption values according to USAAF standard and to Lindbergh, but it would be interesting to know.)

My point regarding the B-29 is that the 195 g/HP/h are an absolute value that is close to the optimum for WW2 era Otto engines, and if you shave off 10% of that you arrive at 175 g/HP/h which is extraordinarily low. For perspective, the optimum figure I found (in Müller, "Junkers Flugtriebwerke") for the turbo-compound variants of the R-3350 running on 115/145 rated fuel is 170 g/HP/h, but that's a significantly improved engine over the R-3350-23 of the B-29 with the benefit of some five years of extra development.

But thanks for checking out the manual - I certainly appreciate that you know more about engines than I do, and if you find something that escaped me, it will be a learning experience for me!

Regards,

Henning (HoHun)

 

[FLYBOYJ]

Hi Flyboyj,

>Lindbergh explained cruise control techniques he had worked out for the Lightnings: reduce the standard 2,200 rpm to 1,600, set fuel mixtures to "auto-lean," and slightly increase manifold pressures.

Certainly - but my impression is that he was able to do that was more the result of the original USAAF "matched power settings" not having been optimized for range beforehand. His strategy matches the procedure the British had established before. (I don't know the V-1710 specific fuel consumption values according to USAAF standard and to Lindbergh, but it would be interesting to know.)

I don't have a P-38 manual in front of me but I do know Lindbergh's methods exceeded chart values within the POH that were based on standard settings (auto lean and forget).

My point regarding the B-29 is that the 195 g/HP/h are an absolute value that is close to the optimum for WW2 era Otto engines, and if you shave off 10% of that you arrive at 175 g/HP/h which is extraordinarily low. For perspective, the optimum figure I found (in Müller, "Junkers Flugtriebwerke") for the turbo-compound variants of the R-3350 running on 115/145 rated fuel is 170 g/HP/h, but that's a significantly improved engine over the R-3350-23 of the B-29 with the benefit of some five years of extra development.

Based on the charts from the FEs manual I came up with the following...

Fuel consumption: 570 gph 42" Hg/2400 RPM @ 25,000 feet

Fuel consumption: 430 gph 38" Hg/2000 RPM @ 25,000 feet

At 2000 rpm that equates a little over 100 gph at cruise.

But thanks for checking out the manual - I certainly appreciate that you know more about engines than I do, and if you find something that escaped me, it will be a learning experience for me!

Regards,

Henning (HoHun)

Thanks Henning - I think the thing to realize that many cruise charts are based on "medium values" based on very standard operation. I think the example of Lindbergh's P-38 career shows that performance charts can be expanded based on established engine operating parameters CHT/ MP/ EGT against RPM at altitude and applying those parameters against the operational environment.

 

[Graeme]

The question I posed was how could an AC engine continue to run with a "jug" or cylinder was shot off like I have heard reported by several writers.

 

[HoHun]

Hi Flyboyj,

>Based on the charts from the FEs manual I came up with the following...

>Fuel consumption: 570 gph 42" Hg/2400 RPM @ 25,000 feet

>Fuel consumption: 430 gph 38" Hg/2000 RPM @ 25,000 feet

>At 2000 rpm that equates a little over 100 gph at cruise.

Is it possible to determine the powers for these exact settings? Then I could calculate the specific fuel consumptions for comparison.

>Thanks Henning - I think the thing to realize that many cruise charts are based on "medium values" based on very standard operation.

Roger that - unfortunately, I have seldom found the charts explicitely specifying for which assumption they are meant. For example, some read "The usual 5% operational margin have not been applied here", others make no comment at all. Some even note "The figures have not been flight-tested yet"!

Regards,

Henning (HoHun)

 

[Crumpp]

they had learned about babying their engines because they were military engines and could take a lot of abuse.

This doesn't sound right to me.

All aircraft engines are constrained by the same physics whether they are civilian or Military.

All the Best,

Crumpp

 

[FLYBOYJ]

For example, some read "The usual 5% operational margin have not been applied here", others make no comment at all. Some even note "The figures have not been flight-tested yet"!

Regards,

Henning (HoHun)

Right now I'm on a project with the USAF where we put upgraded engines in the UV-18 (Twin Otter). Although the mod had been used by civilian operators for a number of years, there were several climb and power setting charts that were never incorporated in the POH. Right now we are developing those charts based on the upgraded engines and will conduct test flights to verify the data. All for a 35 year old aircraft!

This doesn't sound right to me.

All aircraft engines are constrained by the same physics whether they are civilian or Military.

All the Best,

Crumpp

Agree - the only one who "baby's" there engine is the owner operator who also flies his aircraft on a shoestring budget! MHO!

 

[renrich]

If Lindberg said it, and perhaps he didn't, then I guess he did not know what he was talking about.

 

[FLYBOYJ]

If Lindberg said it, and perhaps he didn't, then I guess he did not know what he was talking about.

Well you have the whole 431st FS who bore witness of this....

 

[renrich]

I thought I remember him saying that but I don't know where I read it. If he said that then I am taking it for gospel. To me, at that time, no one knew more about aircraft and flying than Lindberg. I doubt there was any airplane in the world that he could not fly and fly well.

 

[AL Schlageter]

This doesn't sound right to me.

All aircraft engines are constrained by the same physics whether they are civilian or Military.

All the Best,

Crumpp

A civi engine of the time would be being abused it ran at the military normal limits. The military engine would be built 'beefier' than the civi engine.

 

[FLYBOYJ]

I thought I remember him saying that but I don't know where I read it. If he said that then I am taking it for gospel. To me, at that time, no one knew more about aircraft and flying than Lindberg. I doubt there was any airplane in the world that he could not fly and fly well.

Agree...

A civi engine of the time would be being abused it ran at the military normal limits. The military engine would be built 'beefier' than the civi engine.

What do you think was "beefier?"

Take any US civil engine of the period and if it had a civilian variant and you'll find they were built the same - the same Pratt Whitney R-1830-90C that went into the C-47 went into the DC-3. Here is the "Type Certificate Data Sheet for the R-2800. There are little differences (RGB Speeds and water injection) between the military models and the civilian models and there are even notes on how to use the military models in civilian applications.

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/cf0f9435e20432008525676a006759e7/$FILE/ATTIAV5I/5E-8.pdf

 

[renrich]

Perhaps what he was referring to was that the two engines that would be mostly in use in the Pacific at that time would be the Allison 1710 and the R 2800 and they possibly were purposely designed for the military and were not used by civilian AC yet. Would there be a counterpart in the operation of a typical AC engine of the day used say in a Beech Staggerwing to military power?

 

[FLYBOYJ]

Perhaps what he was referring to was that the two engines that would be mostly in use in the Pacific at that time would be the Allison 1710 and the R 2800 and they possibly were purposely designed for the military and were not used by civilian AC yet. Would there be a counterpart in the operation of a typical AC engine of the day used say in a Beech Staggerwing to military power?

Yes - The Staggerwing used several different engines - all had military applications. The R-985 one the model s was the same basic R-985 used on BT-13 or C-45

 

[Crumpp]

Agree - the only one who "baby's" there engine is the owner operator who also flies his aircraft on a shoestring budget! MHO!

That's exactly why I don't rent either!

Guys as FlyboyJ is telling you, the major difference between the Civilian and Military engines was who is the owner of the aircraft.

Power to weight is the major characteristic of an aircraft engine. The physics limits just how "beefy" an aircraft engine can be and still be an aircraft engine.

The physics do not change because of who owns it.

All the best,

Crumpp

 

[kool kitty89]

Also the R-3350 switched to fuel injection in late 1944, which greatly improved reliabillity due to the more uniform and controlable fuel-air mixture, or so I've read.

And I never said anything about the DB-601 having poor efficiency specifically, I don't know a whole lot about that, but I was talking about what I've heard about early fuel-ingected engines compared to carbs. Though I'd expect the advantage of fuel ingection to be more pronounced with larger engines, and high horsepower, particularly if only considdering a single (or maby dual) carborator system.

Also I'm not really sure what's meant by the comparison of the DB-601 to the R-3350, as this is far from an apples-to-apples comparison, with the horsepower and size ranges considderably different, more importantly the comparison of liquid-cooled inline to air-cooled radial engines, as radiald, in general, tend to be less fuel efficient in general iirc.

A comparison of the DB-601 (or maby the 603, 605, or the fuel-injected Junkers-Jumo 210, 211, or 213 engines) to the V-1710 and Merlin lines would be a better comparison. Or, for ratials, the fuel-injected BMW-801 to the R-2800, or (closer in size, power, and with the same cylinder number and configuration) the R-2600.

 

[kool kitty89]

And Elvis, I read some more, and it seems the German engines did use direct-injection, as the same function as in the Diesel termenology.

Though earlier I had been reffering to earlier (and assuming the "direct injection" of the DB-601 and Junkers-Jumo-210 had) incorrectly, was multi-port fuel injection, which is considderably different, though the problems of complexity of timing each ingection for sequential injection of each cylinder (or the inefficiency of using batched or simultaneus injection) would still not not be fully overcome untill the introduction of electronc fuel ingection and the use of engine control units. (particularly for the smaller engines used in automobiles) And fuel injection for auto engines weren't being used untill the 1950's, and even then only on high-end high-performance cars (and for racing).

But as true direct-ingection (over multi-port ingection, as well as carborators) has inherantly higher efficiency, particularly at high power, this may still have overcome the ineffincy of batched or simultaneous injection, though I'm not sure what type the german engines used. It is possible they used sequential ingection, but the complexity and difficulty of such a system in a mechanically ingected system would be daunting, or so I'd expect.

Does anione know the specific type and reglation of injection the DB-601, or Jumo-210 for that matter, used? (ie if it was actual direct injection straight into the cylinder and if sequential, batched, or simultaneous injection was used?)

 

[HoHun]

Hi Koolkitty,

>And I never said anything about the DB-601 having poor efficiency specifically, I don't know a whole lot about that, but I was talking about what I've heard about early fuel-ingected engines compared to carbs.

There were not many fuel-injected engines that came earlier than the DB 601.

>A comparison of the DB-601 (or maby the 603, 605, or the fuel-injected Junkers-Jumo 210, 211, or 213 engines) to the V-1710 and Merlin lines would be a better comparison.

Oh well, you could simply go and do some research yourself before posting stuff "you have read". I have provided data for the Jumo 213, and judging from von Gersdorff et al., the entire Jumo series was just as efficient as the Daimler-Benz series (the Jumo 211F even beating the DB605A's minimum, for example). The same source actually shows the Jumo 210 gaining 8% in fuel economy from the carburetted to the fuel-injected version, too.

The V-1650-7 used 211 GPH at 1640 HP in WEP - 350 g/HP/h. Compare: DB605A - 235 g/HP/h at take-off/emergeny power, Jumo 213E - 258 g/HP/h at take-off/emergency power.

Regards,

Henning (HoHun)

 

[kool kitty89]

I also mentioned that I was thinking in terms of multi-port fuel injection and not true direct-injection (which the DB-601 and Jumo-211 and related engines seem to use) earlier. The direct-injected engines do indeed seem to have better fuel efficience in general, what I was really was wondering about was how the fuel was injected, if batched or simultaneous (less efficient but much simpler) or sequentialy injected. That's one thing I haven't seen when I searched it online (or as a quick reference on google) and I don't have any books that really adress the topic.

And it seems the Junkers-Jumo 210G was the first gasoline engine to use direct fuel injection. I havent done a whole lot of reasearch on it, but it seems this engine used a series of piston pumps driven off the crankshaft with one pump coresponding to each main cylinder and was timed to inject fuel at the right point in the intake cycle. So it seems to have used sequential injection for each cylinder.

Myaby I was wrong, but I'd though that such a sequential set-up would be too dificult to arrange for manichanical injection system. Or maby it was more practical to use on large a/c engines then it was for use in auto engines. Though direct injection seems to have started use with production auto engines in the 1950s it seems that other types of fuel ingection were more practical and considderably less expensive, and I'm not sure if these engines used sequential ingection anyway.