Me109F vs Spitfire MkV

[wmaxt]

[quote="FLYBOYJ
They were manufactured in "matched sets." Great info wmaxt![/quote]

Thanks . Your right they are.

wmaxt

 

[schwarzpanzer]

Supercharging refers very specifically to forced air/fuel induction by means of tapping power directly off the crankshaft to drive the pump

Or also electric or camshaft-driven impellors/compressors, doubt any wereused in WW2, though I remember hearing something like...

Turbocharging refers to tapping power off spent exhaust fumes to drive the pump.

Absolutely correct, but technically a turbo is a form of supercharger.

I was being childish , if you say Turbo, I will know what you mean.

DYK: Me262's were often referred to as Turbo's by their pilots?

Turbo-supercharging refers to using a combination of both a turbocharger and a supercharger, one feeding into the other, to derive even more compression of the air-fuel mixture.

That is actually super-turbocharging.

It is confusing I know!

They needed a long pipe to make the thing work.

Yes, but that's bad for boost, lag and aerodynamics, why bother?

What are "scrolls" and "snails"?

A scroll is a snail @ shaped part of a centrifugal compressor, incorporating the collector etc.

Scroll is an accepted term, I thought it was in the USA?

I can't think of another term right now , sorry!

As far as I know Britain never sucessfully developed a turbo-supercharger which could be mass produced. I know Germany was never able to do so.

Pretty sure both did (@ least 1 FW190)

Your knowlege of turbocharging seems to be based upon modern automotive tech. For aircraft things are quite different. For aircraft, altitude changes must be considered. Super chargers involve gears, normally one stage of a WWII fighter two-stage supercharger is at a fixed gear ratio, and the other either has one or two gears, plus neutral. The maximum pressure (usually called boost) is limited by various considerations, but in English measurments was generally limited to 18, 21, or 25 lbs of boost. With a two speed two stage supercharger, maximum boost can be achieved at two altitudes (called critical altitudes).

Yes it is! I admit my knowledge is limited for WW2-era, I know a Swiss (or Swede? ) developed it @ the turn of the Century, then Garrett of USA mass-produced it.

However I know the did some WW2 planes superchargers were dual stage.

Did some use electromagnetic clutches to change gear then?

I know at least 1 Merlin (prototype) had 1 big 1 little supercharger.

The common UK measurement then was bar (14.7 lbs)

And lbs was just about always written as psi.

The Turbo-supercharger was used on Wright Cyclones, P&W Wasps and double wasps (R-2800's), as well as the Allison (on the P-3

No, I mean a Turbo-compounder, a turbo's exhaust scroll, feeding power directly onto the crankshaft. Only used on the B29 and an Ailiner based on it IIRC?

If the target is a deer, shooting it with anything bigger than a 30/06 is pure over-kill and buys you practically nothing.

The target isn't a deer though.

A point is though 6x .50 will probably work out better than 1 20mm!

1 to 1, I'd still have the 20mm, 800rpm is enough for me.

Thanks for the API .50 info.

The late P-38J and the P-38L were fine up high.

Cheers! Interesting...

Do you know the engine differences?

Most failed quality checks or self destructed during testing.

Good point, what % roughly?

"Boost" (which is actually manifold pressure)

Manifold Absolute Pressure is boost + N/A effects to me (RAM-air, reversion etc)


Overlooked here is that air speed (pulse-tuning) and temperature matter as much, if not more than boost (pressure).

This is why dual-stage manifolds, Hydro/Methanol, No2 and inter/after-coolers are useful.

The inner parts of a Turbo and a mechanical supercharger are NOT interchangeable, turbo's run much to fast and also run hotter (the heat expansion is where they get their power from). P-38s ran in the low 20,000rpm range with 26,400rpm as absolute max

Maybe then usually, but I was thinking of the Rotrex/Garret.

(Centrifugal supercharger running @ aprox 100,000rpm)

I'm sure I've seen a WW2 Turbo of a similar design? a Garret on a P&W IIRC.

These engines seem daft to me: under-square, aprox 6.5:1 CR, 4v-cyl yet SOHC (or even OHV?) 2000RPM max etc?...

The Riley aero engines were lightyears ahead! 8)

(the heat expansion is where they get their power from)

What do you mean?

The exhaust gasses yes, but otherwise...

Lagging (exhaust Turbo heat-containment) is important, but for other reasons (ie cylinder scavenging)

 

[FLYBOYJ]

"Boost" (which is actually manifold pressure)

Manifold Absolute Pressure is boost + N/A effects to me (RAM-air, reversion etc)

US flight manuals make references to both terms, later in the war and even today it's refered at Manifold pressure boost.

 

[wmaxt]

Centrifigul superchargers with compound gearing allowing more than 15/20,000 rpm are recent designs and are normaly used for smaller supercharging applications. Even these impellars don't need the heat resistance of a turbo's impellars.

Supercharging stands for Any forced air system, Turbo-supercharging differentiates mechanical from exaust driven but can also stand for turbo + mechanical supercharging.

Turbo charging is much more diffacult to use because of the plumbing and the pressure regulation. The British ordered P-38s without the turbo's specificaly because they didn't like, trust or want to maintain them. The Merlin was never successfuly turbo charged.

wmaxt

 

[DerAdlerIstGelandet]

Yes but it could be changed a lot quicker than the Derwent and could use crappy metals (could the Derwent?)

And the fact that they had to use crappy metals is why the engine was not that successful. It was not a bad design but Germany lacked the raw materials to make it effective.

 

[Lunatic]

They needed a long pipe to make the thing {turbo-charger} work.

Yes, but that's bad for boost, lag and aerodynamics, why bother?

Hmmm.... it was not that bad for aerodynamics as the pipe is rather narrow and was not protruding. Lag is not such an issue for aircraft, as they don't generally need quick throttle response, that's your car experiance talking again. It didn't hurt boost significantly. What mattered was the end result, which was higher boost at all but the critical altitude of the supercharged plane.

As far as I know Britain never sucessfully developed a turbo-supercharger which could be mass produced. I know Germany was never able to do so.

Pretty sure both did (@ least 1 FW190)

The German's did try to incorporate a turbocharger on one of the late model Dora's, but it was a failure.

Your knowlege of turbocharging seems to be based upon modern automotive tech. For aircraft things are quite different. For aircraft, altitude changes must be considered. Super chargers involve gears, normally one stage of a WWII fighter two-stage supercharger is at a fixed gear ratio, and the other either has one or two gears, plus neutral. The maximum pressure (usually called boost) is limited by various considerations, but in English measurments was generally limited to 18, 21, or 25 lbs of boost. With a two speed two stage supercharger, maximum boost can be achieved at two altitudes (called critical altitudes).

Yes it is! I admit my knowledge is limited for WW2-era, I know a Swiss (or Swede? ) developed it @ the turn of the Century, then Garrett of USA mass-produced it.

However I know the did some WW2 planes superchargers were dual stage.

Certainly. For example the R-2800 on the F4U Corsair incorporated a huge two stage supercharger.

Did some use electromagnetic clutches to change gear then?

I'm not sure of the mechanics, but most involved a barometric switch which would automatically switch gears at a given altitude along with a manual override.

I know at least 1 Merlin (prototype) had 1 big 1 little supercharger.

One of the supercharger stages on the Merilin fit to the top of the engine with part of it nestleed in the V between the cylinders. This was a limiting factor w.r.t. size. The following image is the R2800-18W (F4U-4), the two stage supercharger is everything below the cylinder rings (silver) and is painted grey:

The common UK measurement then was bar (14.7 lbs)

And lbs was just about always written as psi.

If you look at RAE and other British test documents, boost is always refered to in lbs.

The Turbo-supercharger was used on Wright Cyclones, P&W Wasps and double wasps (R-2800's), as well as the Allison (on the P-38)

No, I mean a Turbo-compounder, a turbo's exhaust scroll, feeding power directly onto the crankshaft. Only used on the B29 and an Ailiner based on it IIRC?

I don't believe anything like this was used on the B-29.

A point is though 6x .50 will probably work out better than 1 20mm!

1 to 1, I'd still have the 20mm, 800rpm is enough for me.

Well I'd agree with that. One for one, most 20 mm were superior to the .50 BMG (there were some exceptions like the Japanese Type 99-I).

Most {Jumo jet engines}failed quality checks or self destructed during testing.

Good point, what % roughly?

Well I'm not sure there are any official figures. But with some 15000+ units having been bullt and only a a little over 1000 having been utilized (including both combat and test aircraft) it would seem that the great great majority were defective.

-----------

Shchwarz - please indicate who you'r quoting. Simply change the {quote} to {quote="Lunatic"} if your quoting me (using square not curly brackets). Or only reply to one person per post.

Thanks,

Lunatic

 

[FLYBOYJ]

No, I mean a Turbo-compounder, a turbo's exhaust scroll, feeding power directly onto the crankshaft. Only used on the B29 and an Ailiner based on it IIRC?

I don't believe anything like this was used on the B-29.
Lunatic

Lockheed Constellation, P2V and the Douglas DC-7 used turbo compounds. The B-29 used an R3350-23 with a turbo supercharger.

 

[DerAdlerIstGelandet]

I did not know that about the Constellation. Great plane. I remember sitting in Eisenhowers Constellation at Fort Rucker, Alabama. I really like the Connie.

 

[FLYBOYJ]

I think the Connie epitomized Lockheed's heyday in the late 50s and early 60s. C-130, F-104, U-2, P-2, and the Connie were in full swing and on the drawing board was the SR-71, Electra, P-3 and Polaris missile. What a time to be working there!

 

[DerAdlerIstGelandet]

I agree it must have been exciting.

 

[schwarzpanzer]

[quote="wmaxt]Even these impellars don't need the heat resistance of a turbo's impellars. [/quote]

Nor the inter/after-cooling...

The heat is just due to the proximity of the exhaust and can nowdays be offset by ceramic-coating and lagging, heat dissipation etc.

[quote="wmaxt]Supercharging stands for Any forced air system, Turbo-supercharging differentiates mechanical from exaust driven but can also stand for turbo + mechanical supercharging. [/quote]

I understand you, but it has been rammed into my head untill I am pedantic! The correct term for turbo + mechanical supercharging is Super-Turbocharging.

Hmmm.... it was not that bad for aerodynamics as the pipe is rather narrow and was not protruding.

I heard that the P47 was so fat because of the piping?

I heard it even went round the cockpit?!

is not such an issue for aircraft, as they don't generally need quick throttle response

What if the engine stalls and needs a bump-start?
Would it be important then?

the R-2800 on the F4U Corsair incorporated a huge two stage supercharger.

Yeah, I'd heard of that one, thanks for the piccy!

I'd heard it was big, but didn't think that big!

I'm not sure of the mechanics, but most involved a barometric switch which would automatically switch gears at a given altitude along with a manual override.

Cheers for that, I've got a WW2 diagram of the mechanisms
(in pdf format) but I can't send it for some reason.

There were 2-speed and 2-stage of various designs and some were a combination of both!

If you look at RAE and other British test documents, boost is always refered to in lbs.

You're kidding?

I don't believe anything like this was used on the B-29.

I'm honestly not sure, the engine was the Wright R-3350 Turbo Cyclone, what plane(s) was this used in?

Cheers for the Jumo figures Lunatic and I've changed my quoting habits as you requested.

The B-29 used an R3350-23 with a turbo supercharger.

Can you check if any used the Wright R-3350 Turbo Cyclone?

- That had a Turbo-compounder.


This is not for the Me109F, but I need to get it off my chest! :

In the BoB the Me109E's had their cannons in the wings and not firing through the hub, right?

However the Bertha, Caesar or Dora did?

If the Emil did, would this have caused more Spit/Hurri losses?

Also the interrupter gear for the 2 7.92mm's weighed a ton, so why not ditch them and have just 3x 20mm's?


Another point is that I think the DB605 was overbored for the Gustav?

- That would have made it an over-square engine? The only one in WW2? 8)


BTW: Scrolls/snails - usually called diffusers in WW2 and usually look very different, so not interchangeable.

IIRC there was one though...

 

[Lunatic]

Yes but it could be changed a lot quicker than the Derwent and could use crappy metals (could the Derwent?)

And the fact that they had to use crappy metals is why the engine was not that successful. It was not a bad design but Germany lacked the raw materials to make it effective.

Even the version of the Jumo which didn't use "crappy metals" (the A version I believe???) still had a very short operational lifespan and high failure rate. The technology was just too new and the German mass production processes were not up to the precision needed to build them.

=S=

Lunatic

 

[Lunatic]

I heard that the P47 was so fat because of the piping?

I heard it even went round the cockpit?!

Here's some material on the GE Turbocharger:

http://rwebs.net/avhistory/opsman/geturbo/geturbo.htm (the whole site is worth full investigation).

=S=

Lunatic

 

[schwarzpanzer]

Even the version of the Jumo which didn't use "crappy metals" (the A version I believe???) still had a very short operational lifespan and high failure rate.

24hrs flight time, if you overrun it the turbines could be ejected!

The technology was just too new and the German mass production processes were not up to the precision needed to build them.

The bombing wouldn't have helped either?

Your last post is nice Lunatic, but there's a purple band obscuring part of the key.

1 is exhaust piping, the other?

I'll have to check that link out, thanks!

Here is some great info that I promised:

http://www.enginehistory.org/OX5to3350.pdf

 

[FLYBOYJ]

I heard that the P47 was so fat because of the piping?
I heard it even went round the cockpit?!

The correct term is "ducting." Piping is found in houses and boats!

The B-29 used an R3350-23 with a turbo supercharger.

Can you check if any used the Wright R-3350 Turbo Cyclone?
- That had a Turbo-compounder.

The B-29 or the B-50 never used the turbo compound as far as I know. I believe it was introduced after the war and the Connie and DC-7 were amoung the first aircraft to utilize it.

 

[schwarzpanzer]

The correct term is "ducting." Piping is found in houses and boats!

Aaah! I was gonna say plumbing, that would've been correct! damn.

The B-29 or the B-50 never used the turbo compound as far as I know. I believe it was introduced after the war and the Connie and DC-7 were amoung the first aircraft to utilize it.

See the link I posted above.

 

[FLYBOYJ]

The correct term is "ducting." Piping is found in houses and boats!

Aaah! I was gonna say plumbing, that would've been correct! damn.

That would of worked too!

Tool terms you never say around an aircraft mechanic...

piping

sheet metal gage

"body" instead of "fuselage."

Claw Hammer

"snippers" instead of "dikes" (Diagonal pliers)

compression checker

skyhook

If you use skyhook in the same sentence with any of the above you'll either be laughed at, punched, or thought to be a former toilet cake changer!!!!

 

[DerAdlerIstGelandet]

Nice post up there about the P-47 supercharger system. If you dont mind I will copy that one for my own information collection. 8)

 

[wmaxt]

Actualy any supercharging above 6 lbs needs to be cooled in some manner by 12lbs boost, temps of over 400deg are common and efficiency dropps dramaticaly and detonation rises, this requires retarded ignition and a corresponding drop in power. Even the Merlin had an intercooler/aftercooler (the same thing actualy as they are both between the supercharger and the engine).

I've been around a while and never heard the term "Super Turbocharging" I've only known of Supercharging (mechanical) Turbocharging (exaust driven) and Turbo-Supercharging (Turbo into mechanical. The Turbo is always first in these systems). Maybe Flyboy can help with this one?

The Connie was designated a C-69 in WWII and flew operationaly in late '44 and in '45. I don't know if it ever saw enemy action though.

wmaxt

 

[FLYBOYJ]

Actualy any supercharging above 6 lbs needs to be cooled in some manor by 12lbs temps of over 400deg are common.

I've been around a while and never heard the term "Super Turbocharging" I've only known of Supercharging (mechanical) Turbocharging (exaust driven) and Turbo-Supercharging (Turbo into mechanical). Maybe Flyboy can help with this one?

I think this was a propaganda term by the manufacturer?!?

The Connie was designated a C-69 in WWII and flew operationaly in late '44 and in '45. I don't know if it ever saw enemy action though.

wmaxt

I think the C-69 was entering service right at the war's end

Great link about the connie....http://www.ruudleeuw.com/connie-text.htm