Superchargers

[Vinkman]

When looking at the difference between the Allison V12 and the Rolls Royce engines it's true that the Alison suffered with inadequate Supercharging until the P-63. What I find interesting is all the fame given to the Rolls royce supercharger developer Stanley Hooker, who for sure improved them greatly. The reason this seems so curious is that all of hookers designs, and the P-63 design make use of compound Supercharging. In fact almost every Allied design I can think of, has a mechanical, centrifugal supercharger, and an auxilary stage that is either a turbo-supercharger, and another centrifugal supercharger. There were singe stage planes, P-40, P-39, perhaps most of the russian designs but most of those lacked High altitude performance....

...except two.

The DB600 series. These engines used a singe, mechanical, centrifugal supercharger, and achieved power and altitude numbers on par, or better than almost all of the compound units. Yet I've looked and looked and can't find who the supercharger developer was for the Diamler.

The unit seems to be a fluid coupled unit, in that the engine turns an impeller that pumps fluid to a turnbine that turned the supercharger. A similar system was used for the Aux stage of the P-63 Allison, but the allison still needed the engine stage charger as well.  The diamler unit was compact, and very effective.

The 'other' were the R2800 equipped Planes (F4U, F6F) which opted to included a gearbox that allowed the single stage charger to shifted into a higher gear an high altitude.

but the German design seems very ahead of it's time, and yet little is known about it. Anyone have a reference book or other information about the design of the DB600 serier Supercharger?  

[Tank-Ace]

Don't quote me, but I believe the Daimlers had a two speed supercharger as well. Not sure of the mechanism, but the only thing I can figure is the it had a 2nd gear.

Also remember that any performance charts of late war engines are likely using MW 50 boost as well.

I'll see what I can dig up for you; there's probably more info on the German pages.

[Vinkman]

Don't quote me, but I believe the Daimlers had a two speed supercharger as well. Not sure of the mechanism, but the only thing I can figure is the it had a 2nd gear.

Also remember that any performance charts of late war engines are likely using MW 50 boost as well.

I'll see what I can dig up for you; there's probably more info on the German pages.

It could be although the 2 speed units usually have a saw tooth shaped performance curve for the plane, but perhaps the fluid coupling smoothes that effect out. thanks for anything you can find. 

[Denniss]

DB 605L and 603L with two-stage superchargers did not see wartime service, all 601/603/605 engines had a single stage supercharger with fluid coupling.

[Charge]

"The reason this seems so curious is that all of hookers designs, and the P-63 design make use of compound Supercharging. In fact almost every Allied design I can think of, has a mechanical, centrifugal supercharger, and an auxilary stage that is either a turbo-supercharger, and another centrifugal supercharger."

Where did you get this? The only one that had this to my knowledge was P63 and even that one was not a pure "compound" solution. I understand that compound means that the first stage feed directly the second stage and I'm not sure if that was established in P-63.

The usual configurations were:

-one stage+one speed (Spitfire I)
-one stage+two speed (Spitfire XII, FW190A)
-two stage+one speed(per stage) (SpitfireVII, FW190D9, P51)
-two stage+one and two speed (3 speeds in total) (Ta152)
-turbosupercharger (P47, P38)

Other:
-Szydlowsky Planiol, variable vane single stage variable speed supercharger (Dewoitine D520)
-DVM liquid coupled single stage variable speed supercharger (Bf109)

I'm not sure of the types of superchargers in Spitfires but I'm pretty sure I'll be corrected swiftly...  

-C+

[Denniss]

Jumo 213A of Fw 190 D-9 was one stage + two speeds as well. The 213E of the Ta 152H just added an high-alt second stage.

[nrshida]

Ah, I read about this recently but I can't remember where.

Apparently the single stage supercharger with the fluid coupling behaved somewhat like a multistage blower.

I've got some manuals around here somewhere...

[Denniss]

It behaved better than that - continuous boost pressure increase, just as much as the engine required (maybe with a little overboost) so smooth power curves. Not the spikes one has with two speed/-stage blowers

[nrshida]

Yes, like continuously variable transmission rather than discrete gearing.

[Vinkman]

"The reason this seems so curious is that all of hookers designs, and the P-63 design make use of compound Supercharging. In fact almost every Allied design I can think of, has a mechanical, centrifugal supercharger, and an auxilary stage that is either a turbo-supercharger, and another centrifugal supercharger."

Where did you get this? The only one that had this to my knowledge was P63 and even that one was not a pure "compound" solution. I understand that compound means that the first stage feed directly the second stage and I'm not sure if that was established in P-63.

The usual configurations were:

-one stage+one speed (Spitfire I)
-one stage+two speed (Spitfire XII, FW190A)
-two stage+one speed(per stage) (SpitfireVII, FW190D9, P51)
-two stage+one and two speed (3 speeds in total) (Ta152)
-turbosupercharger (P47, P38)

Other:
-Szydlowsky Planiol, variable vane single stage variable speed supercharger (Dewoitine D520)
-DVM liquid coupled single stage variable speed supercharger (Bf109)

I'm not sure of the types of superchargers in Spitfires but I'm pretty sure I'll be corrected swiftly...  

I got it from the reviewing designs of the Merlins that powered the Mustang, and the later Spitfires which were compound units, as were all the ones that followed. Didn't know the Spits through XII were a single stage, with two speeds. Yes P-63 was a true compound arangement, with the Aux feeding the engine stage. P-63 has a similar performance curve to that discribed by Shida and Dennis where the engine made full boost almost to max alt.