Author Topic: F4U/190 supercharger question (Read 1005 times)

Regurge · « **on:** February 20, 2002, 03:57:04 PM »

Looking at the speed charts for F4Us (and F6F), they all have 3 peaks, as if they had 3-speed superchargers. But I believe they were 2 speed like many other planes (190A, spit, p51, etc), but these others only have 2 peaks. Why is that?

Also, anyone know why the Germans didnt fit a larger supercharger in the 190As, or change the gearing in the existing one to improve hi alt performance? It seems to have worked fine for Spits and P51s.

gripen · « **Reply #1 on:** February 20, 2002, 05:23:04 PM »

The supercharger system in the F4U was a two stage system. At low altitude it could be operated as single stage single speed system (ie engine stage alone) if required manifold pressure was not very high (say less than 70") ie supercharger at "neutral" position. At higher altitude second stage (auxlirary stage) was needed for high manifold pressures and it was a two speed system ie "low " setting for lower altitudes and "high" setting for higher altitudes.

There were several BMW 801 developements with advanced superchargers (like four speed system or turbo versions) but these did not see large service or more than experimental stage of developement.

gripen

Hooligan · « **Reply #2 on:** February 20, 2002, 05:31:35 PM »

Does this mean the F4U had a 2 stage/2 Speed supercharger and the 190 had a 2 stage/1 Speed supercharger?

Hooligan

gripen · « **Reply #3 on:** February 20, 2002, 05:41:22 PM »

Well, correct way to say this should be something like:

The F4U had two stage supercharger system where engine stage was a single speed system and auxilary stage was a two speed system. And the engine could be operated with the engine stage supercharger alone so in practice there were "three speeds" available despite it was not a real three speed system like some Griffons or Jumos. Late F4Us had variable speed auxilary stage like some V-1710s.

The BMW 801 was a pure single stage two speed system.

gripen

lazs2 · « **Reply #4 on:** February 20, 2002, 08:07:48 PM »

PW2800's had a two stage two speed supercharger (47's also had turbos) FW's had single stage two speed superchargers. The difference is large at higher alts.

Put simply... two stage is compressing the air twice...much like a home air compressor of two stage design. Two speed is much simpler. it involves nothing more than gearing and "shifting gears" to spin the supercharger faster to compress more air.

Two stage superchargers are very complex and the germans simply couldn't make em. Every country does some things better than others. American's made very good superchargers, ships and fighter planes . Germans made good incinerators.
lazs

Regurge · « **Reply #5 on:** February 20, 2002, 08:28:25 PM »

Thanks gripen, that makes alot more sense now.

What I was getting at with the 190 is that some Merlin engined rides had 2-speed/1-stage superchargers tuned for high alt and others tuned for low alt. Just wondering why that wasn't true for the 801s.

Pongo · « **Reply #6 on:** February 20, 2002, 09:15:34 PM »

I believe it was tried but the metals required to mass produce it were not available. Cant remember where I read that.

gripen · « **Reply #7 on:** February 20, 2002, 11:44:06 PM »

The Germans had couple two stage systems (Jumo 213E and F, DB 603L and 605L) and also turbos (BMW 801TQ) in the production but these did not reach large service.

It should be also noted that basicly most WWII turbo systems were two stage systems ie engine stage was mechanical and auxilary stage was turbo . Also some single stage systems did pretty well at high altitude like the DB 605AS and D.

gripen

Nath[BDP] · « **Reply #8 on:** February 21, 2002, 12:29:07 AM »

The BMW801D-2 had a two speed supercharger; which is the powerplant we have on both the Fw 190A-5 and A-8.

Source: "KURT TANK: Focke Wulf's Designer and Test Pilot", by Wolfgang Wagner (Schiffer publishing).

Focke Wulf Fw 190 in Combat by Sir Alfred Price.

MANDOBLE · « **Reply #9 on:** February 21, 2002, 02:13:32 AM »

Regurge, germans used a different system to increase hi alt performance. The 190A8 R4 had a GM-1 bottle instead the aux fuel tank. GM-1 was also used by 109 and Ta152.

Wilbus · « **Reply #10 on:** February 21, 2002, 05:57:00 AM »

How can you see it on the Charts what they are? Can you?

The Jumo E-1 that the TA152 is suposed to use is 2 Stage 3 Speed engine, capeble (with GM1) of getting the TA152 up to 760 Km/h at 12,500 meters (41k). Since our AH charts have been choped off from 30k and up, we can't see it anymore, however, AH TA152 only does bout 460 at 35k, equal the the P51 B at the same alt in AH.
(TA152 slightly faster).

Think we might not have the 3:d gear on our engine.

Is every little extra step on the chart new place where the engine get a little kick?

Wilbus · « **Reply #11 on:** February 21, 2002, 06:03:44 AM »

Found the old Chart of AH TA152.

http://www.hitechcreations.com/cgi-bin/charts.pl?vehicle=ta152h

Naudet · « **Reply #12 on:** February 21, 2002, 07:19:40 AM »

Hey this old chart, shows the TA152 way to slow.

Top Speed i think was around 472 mph, not the "Slow" 460 in the chart.

Wilbus · « **Reply #13 on:** February 21, 2002, 10:06:56 AM »

Yes Naudet, why I show it

The new chart is the same only that HTC has cut it in half (almost).

Think HTC might have modelled the wrong engine for it.

Wilbus · « **Reply #14 on:** February 21, 2002, 10:08:25 AM »

With the right engine, it would be better up High then it allready is, better climb and better speed.