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Carpurator vs Flying Envelope


dov

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Halllo

My question concerning carpurator: As far as I am informed, the carpurator of the Zero was the only one, which was operative in all positions of the flying envelope.  Is this correct?

I know something about the German injection system too.

The RAF had to handle it with limitations of the FE. 

How about American systems? Copy or own developement?

But the question still alive is the lubrication system on the Zero overalm the FE!

Can you have proper answers to this question?

Happy modelling 

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53 minutes ago, dov said:

Halllo

My question concerning carpurator: As far as I am informed, the carpurator of the Zero was the only one, which was operative in all positions of the flying envelope.  Is this correct?

 

No. A Carburetor/Carbureter is always operating.

https://en.wikipedia.org/wiki/Carburetor

It might have optimum ranges of operation depending on altitude, attitude and temperature and combinations thereof, but the idea is it always works. 
Otherwise, no combustion.

 

 

53 minutes ago, dov said:

I know something about the German injection system too.

The RAF had to handle it with limitations of the FE. 

If you use a float chamber system, a non-upright attitude or during negative G will not behave nicely. 
Hence the need for a restrictor, or switching to a different chamber design.

Incidentally, fuel injection was considered and worked on for the Merlin, but a rather conservative engineer in the upper ranks decided it wasn't worth the trouble. Manifold injection was introduced in 1943. 

 

53 minutes ago, dov said:

How about American systems? Copy or own developement?

 

Sorry, I don't see the point of positing the question in that way.

Engine development and aerodynamic data and theories was frequently shared between almost all parties involved via NACA reports with input from many experts from Germany, Britain, US, France and others.
Harry Ricardo's  work was influential for all sides.

 

53 minutes ago, dov said:

But the question still alive is the lubrication system on the Zero overalm the FE!

What question exactly?

 

 

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If you are genuinely interested in aircraft engine development, I can recommend Callum E. Douglas "The Secret Horsepower Race" on engine development (primarily in England and Germany) up to and during WWII

 

/Finn

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1 hour ago, dov said:

But the question still alive is the lubrication system on the Zero overalm the FE!

Is this referring to whether the zero had a engine lubrication system that allowed inverted flight for longer than usual time? I can't answer thant but someone might be able to if it is made clearer. Some times on-line translations do not cope well with technical terms.

Steve.

 

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The carpurator system allowed the Zero to fly all possible maneuvers of the EF. I do not have a clue if the lubrication system was also designed to it.

Actually what my basic question is: The a/c is designed for a optimal EF. Aux system performance do not cope with the aerodynamic EF.

Intended, no solution, no care, so the EF is then just theretical!

Happy modelling 

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18 minutes ago, dov said:

The carpurator system allowed the Zero to fly all possible maneuvers of the EF

It is said to be a float carburetor system, but I suspect they may have used a diaphragm chamber or restrictor similar to what was introduced in 1940 on Merlins (yes, Ms. Shillings' quick fix indeed).

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3 hours ago, Bozothenutter said:

/close thread

Well he didn't get around to Japanese engines, so we can still bash that around have a polite discussion about suck-squeeze-bang-blow thingies from the Far East ;)

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8 minutes ago, alt-92 said:

Well he didn't get around to Japanese engines, so we can still bash that around have a polite discussion about suck-squeeze-bang-blow thingies from the Far East ;)

Second book?

And to be honest,  development of the Japanese engines was pretty static, compared to what happened in Europe. 

No 'horsepower race' there....

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20 minutes ago, Bozothenutter said:

No 'horsepower race' there....

Not for a lack of need nor trying ;)  

Despite the preference for non-liquid cooled engines in both air arms, there certainly were several development lines for either turbosupercharged or high-powered dual-stage compressor equipped radials. The lack of suitable raw materials on the one hand, and a distinct difference in manufacturing processes (lots of small subcontractors, and relatively little automation) on the other is what hampered those advances. 

I do have to admire the engineering in the sense that they managed to get pretty good power from a relatively small package when you look at the displacement vs HP ratio.

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For japanese engines, if there is an answer, it is probably here:

 

 71zS9qkGfXL._SL1500_.jpg

 

I'll have a look later and report any findings. After all, the carburetor air intake changed between Sakae 12 (A6M2, bottom front of cowling) and Sakae 21 (A6M3, top front of cowling), so maybe there is something to it.

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As I understand it,  the American 'carburettors' were more akin to what we now call single point injection.

As others have pointed out (and it's in the book!)

The someone high up in the RAE didn't think injection was worth it, so that got nixed.

The Germans had been working on practical injection for a while, aero- and automotive, using high pressure mechanical pumps,  that would later be universal in diesel engines.

 

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38 minutes ago, Fukuryu said:

After all, the carburetor air intake changed between Sakae 12 (A6M2, bottom front of cowling) and Sakae 21 (A6M3, top front of cowling), so maybe there is something to it.

That might be the switch to indirect (single point) injection, which was also used on Mitsubishi engines.

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As I read the Maru Mechanic about the Zero developement,  first off all was the carpurator. This system was checked on American and European designs, and found unsuitable. Since in inverted flight they got black smoke out of the exhaust and engines quit. After the carpurator was new designed by the Japense  to give enough mixture during absolving a full aerobatic FE (Flying Envelope) this was taken over to the Zero!

This system worked.

But how was the lubrication handled in negative G or zero G intervalls?

How were both system handeld at the Allied a/c?

Did American a/c the ability of unlimitted flying in all areas of the FE? Or were there sever restrictions?

Happy modelling 

 

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I'm assuming lubrication was by 'dry sump', as used in racing cars.

Why? Because of the size of the oil tanks in most aircraft.

This means the system is always pressurised, and there's a 'buffer' of oil in the tank to prevent scavenging problems.

I understand that the American radial engines oiling system was the same, though they got a reputation for using a lot of oil.

In racecars this system is used for space saving/CG purposes. (Dry sump makes an engine lower, so it can be placed lower in the chassis)

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Generally speaking, the engines weren't fitted with "fully inverted" oil systems.  That's something fairly particular to engines specifically intended for "aerobatic" aircraft, where sustained inverted flight is expected.

 

As an example, I found in the P-51A flight manual:

 

Oil System: The oil tank, located on the forward side of the fire wall, is designed to allow the airplane to assume any attitude when the tank is full, and feed adequately in a vertical climb or dive when the tank is only one-fourth full.

 

Acrobatics: The acrobatic qualities of this airplane are exceptional, and the lateral control is excellent at all speeds. All normal acrobatics are permitted; however, inverted flying must be limited to 10 seconds because of loss of oil pressure and failure of the scavenger pump to operate in inverted position.

 

Perhaps this is one reason for the raised eyebrows when Maverick stated "We were inverted."

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