Hardest plane to take down in WW2?

[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]

Originally Posted by Crumpp

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]

Originally Posted by 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.

Agree...

Originally Posted by AL Schlageter

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]

Originally Posted by 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?

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.

[kool kitty89]

Did the V-1710 use a "pressure carburetor" and I'm not sure but does a "pressure carburetor" work like a throttle-body injection unit?

It used a Bendix produced carb, which had a larger market for "pressure carburetors" in the late 1930s leading up to WWII, or so I've read.

[Elvis]

kool kitty89,

Seems you're confusing some terminology here.

Robert Bosch figured out the whole "sequential" thing back in the '20's (I believe) when he came up with the idea of the Injection Pump.

Don't recall if I went into that much detail last time, but basically you have two types of injectors; the style that uses a separate Injection Pump and the style that doesn't use a separate Injection Pump (commonly known as a "Unit Injector").
The style that uses an Injection Pump is the type I believe we're working with here.
What happens is that fuel is drawn up from the tank via a typical fuel pump.
This pump sends the fuel through a filter and into the Injection Pump at "low" pressure (5-7 psi).
The injection pump can take on two forms - inline and rotary (sometimes referred to as a "distributor-style", because it looks a little like the distributor on your car).
I believe the DB601 used the inline style (trying to remember from the cutaway I've seen a couple of times).
Anyway, what happens is the pump has several small chambers each with a tiny little piston, called a "plunger". Each chamber corressponds with each cylinder on the engine.
So if you have a 6 cylinder engine, your pump is going to have 6 chambers.
If its a 12 cylinder engine, then the pump has 12 chambers. See?
Because of the small size and the fact that the injector (in this case) is basically a poppet valve in a nice shaped "case" builds the fuel up to a much higher pressure (in a diesel engine, it is not uncommon for fuel to be pressurized to around 1500 psi or more. On a modern gasoline car engine its much less, around 40-50 psi).
The combination of the higher pressure of the fuel and the shape of the opening at the end of the injector creates a fine "misting" of the fuel which allows it to burn much more readily, thus combustion is quite efficient.

With the Unit Injector (commonly seen on Detroit 2-stroke and EMD diesel engines) the Injection pump is part of the injector itself.
Basically the plunger is in the injector and fuel is fed directly into it at low pressure via the fuel pump.


MULTI-PORT INJECTION, simply means you have a separate injector at each cylinder.
The alternative to that would be a "Throttle Body" (what GM used to refer as "TBI", meaning "Throttle Body Injection").
A Throttle Body is bascially a carb, but instead of its usual jets and floats, an injector is shoved inside each venturi (assuming more than one) and fires off whenever an intake valve opens up.

So MPI and Seq. Injection are actually two different things, with the only connection between them being that they both deal with Fuel Injection.


Even today, just about every car that still uses what we now call "Mechainical Fuel Injection" (which is pretty much relagated to diesels these days) is based on the Robert Bosch design, no matter what maker's name is embossed on the body of the pump.




Elvis

[kool kitty89]

I understand that now (earlier I had confused a few things). I was wrong about the fuel efficiency, I'd been thinking all early systems used "simultaneous" or maybe "batched" injection and not "sequential" injection. (although those were more common on the first automobile engines using direct gasoline injection iirc)

FLYBOYJ (on another thread) described a "pressure carburetor" which sounded like a similar mechanism as single-point injection/TBI. This type of mechanism wouldn't be affected by changing G-forces (particularly -G) and since the V-1710 used a Bendix carburetor (a company known to have a strong market in "pressure carbs" leading up to the war) and since the V-1710 never seemed to have -G induced cut-out it would make sence that it used this mechanism.

It would make sence that someone would use this type of mechanism on a military a/c engine durring the war since the concept is a compromise between a carburetor and "direct fuel injection" having no problems with g-loads and being about as simple as a normal carburetor (albeit with a pressure pump) although somewhat lower performance than "direct injection" in terms of power and throttle response.

[FLYBOYJ]

KK just caught up to this and you are correct.

[kool kitty89]

Ok. Thanks, that certainly makes sence.