Author Topic: Uber 190A8 (Read 372 times)

MANDOBLE · « **on:** June 11, 2002, 08:06:43 AM »

Did it use really MW50 in the third tank? If not, was that tank normally used for normal fuel? If yes, did the increased range justify the increased weight, decreased acceleration/climb rate and top speed? If no, why to keep that tank inboard?

Answers for the A8 AH version: No, Yes, No, dont know.
Answers for the real A8: ?, ?, No, dont know.

Don · « **Reply #1 on:** June 11, 2002, 03:06:28 PM »

Mandoble:

The FW 190A-8 was powered by the BMW 801D-2 radial engine in a form with the GM1 nitrous oxide power boost system. It had a 25.3 imperial gallon increase in internal fuel capacity thru the introduction of a small aux tank in the rear fuselage. The type was the final production model of the FW 190 A series built from 1943 on.
Maximum "clean speed" at 20,670 feet was 408 mph; maximum rate of climb at sea level was 3,445ft per minute; climb to 19,685ft was 9 minute 6 seconds. (note: this is not true of the AH FW 190A-8; not even close)

funkedup · « **Reply #2 on:** June 11, 2002, 03:14:57 PM »

Quote

this is not true of the AH FW 190A-8; not even close

?????????

http://www.hitechcreations.com/models/190a8.html

Jochen · « **Reply #3 on:** June 12, 2002, 03:57:05 AM »

What is this recent talk about GM1 in Fw 190? It does not make any sense.

1. GM 1 helps only at high altitudes by providing extra oxygen to burning process. Few 190's tested GM 1 but it was considered useless.

2. Bf 109's Staffels were used as high cover for Fw 190 Gruppen. These 109's usually had GM 1. It made much more sense give GM 1 to 109's to achieve superb performance at high altitude than give them to 190's to achieve mediocre high alt performance.

and

3. GM 1 requires pressurized bottles like oxygen. Fw 190 AUX tank behind cocpit is ordinary fuel tank that would not withstand pressure of GM 1 liquid.

Samm · « **Reply #4 on:** June 12, 2002, 04:09:08 AM »

Awesome ! A Mando thread ! Ah yeeeeah .

MANDOBLE · « **Reply #5 on:** June 12, 2002, 04:51:12 AM »

Jochen, the fact is that this thread is about MW50 usage, not GM-1.
The schematic drawings of 190A8 featuring GM-1 show a single big pressurized bottle instead of the aux fuel tank, very different in shape. That bottle was much bigger than those used in pairs by the 109s.

About the usefullness of GM-1 in the 190A8 it depends on the performance improvements above 22k, where they needed to intercept the buff formations. GM-1 was, for sure, useless for the eastern front 190s.

Wilbus · « **Reply #6 on:** June 12, 2002, 01:06:55 PM »

Mando, like I just typed in another thread (OK this is abit off topic) the GM1 only works above the engines Maximum boost altitude, thus at 22k, it's useless. Not untill around 30- 35k or so does the BWM 801D-2 reach it's maximum boost altitude (it was bad already down at 25k though)

Don, hope I don't offend you but that text seemed very much copied. The A8 wasn't really the final production version, it was the one produced in most numbers but there were quite some A9's produced (and flown in combat) after the A8. Maybe I just have a different view on final production version.

As for MW50 in the A8, it makes ALOT more sence then the GM1.

Vermillion · « **Reply #7 on:** June 12, 2002, 03:13:43 PM »

Well, I don't know what "makes sense" but I have the Fw190A8 Technical Handbook thats been shared extensively on this BBS. This handbook is an English translation of the original German document which would be considered a primary source.

The documents talk extensively about A8's equipped with GM1, and provides performance curves for planes equipped with it. However, there's no such mention of MW50 (that I can remember), and it definitely does not have performance data for a A8 with MW50. I'll check when I get back back home (away on business travel this week).

HoHun · « **Reply #8 on:** June 13, 2002, 02:32:32 AM »

Hi Mandoble,

>Did it use really MW50 in the third tank?

I don't think the Fw 190A-8 was ever used with MW50. (I could be wrong, though :-)

>If not, was that tank normally used for normal fuel?

Yes. Normal fuel could be injected into the supercharger air intake, though, achieving a similar effect as MW50, raising the boost from 1.42 ata to 1.58/1.65 ata for some extra horsepower. The boosted Fw 190A-8 achieved similar speeds as the Fw 190A-5, and with identical equipment probably came close in climb rate.

>If yes, did the increased range justify the increased weight, decreased acceleration/climb rate and top speed?

Apparently, since the tank was kept in most instances :-)

>If no, why to keep that tank inboard?

It wasn't always kept: The Soviets captured a "light-weight" Fw 190A-8 without outer wing guns, rear fuselage tank, bomb racks etc., and probably without the radio equipment necessary in the home defense. It had just below 4000 kg, about what the A-5 weighed, too.

>The schematic drawings of 190A8 featuring GM-1 show a single big pressurized bottle instead of the aux fuel tank, very different in shape. That bottle was much bigger than those used in pairs by the 109s.

The final form of GM-1 usage in the Me 109 consisted of a single pressure vessel just like the one you describe for the Fw 190. I think before its introduction, smaller vessels were used in quadruples, not in pairs though.

>About the usefullness of GM-1 in the 190A8 it depends on the performance improvements above 22k, where they needed to intercept the buff formations.

The chart Furious posted indicates that GM-1 could be used from 8 km up. The RPM reduction does not necessarily indicate a heat problem - remember that GM-1 provides additional oxygen without the need to spin the supercharger as fast as possible, so a lower RPM setting might as well indicate a new optimum operating point for the engine with less power used for operating the supercharger. Maybe the increased propeller efficiency at lower Mach numbers also plays a role.

Still, it's true that GM-1 use seems to have been limited by thermal considerations. GM-1 provides the same amount of power at sea level as it does at altitude, and it could have provided 250 HP as low as 2 km without mechanically overstressing the engine.

Regards,

Henning (HoHun)

senna · « **Reply #9 on:** June 13, 2002, 03:22:05 AM »

Hum, propeler mach numbers at higher alt, very interesting.

MANDOBLE · « **Reply #10 on:** June 13, 2002, 03:52:59 AM »

Henning, so, with petrol injection and MW50 the engine can achieve the same maximum boost pressure without inmediate damage, right? Lets suppose 1.65 ata. But how many minutes before serious overheating with petrol and how many with MW50?

What it is clear for me is that the real boost system was the GM-1, AFAIK MW50/25/75 was able increase maximum the boost a bit, but its main function was to act as a cooling. Does that mean that MW50 may be used even at much lower ata just to cold down the engine? May it be used with GM-1 at the same time to counteract the reheating effects of the GM-1 usage?

butch2k · « **Reply #11 on:** June 13, 2002, 04:21:56 AM »

using GM-1 or oxygen to get higher performance raised cylinders head temperature by more than 50 degree IIRC tests made by US and British engineers. Moreover handling of liquid nitrous oxyde was not very easy and it was quite scarce as i mentionned before. Oxygen had also a deleterious effect on the supercharger, corroding some parts very fast. Moreover it can't be used below the engine critical altitude because of mixture richness problem which might result in knocking.
As war went on the introduction of engine with higher critical altitude relegated the use of GM-1 to very high flying aircraft, mostly recce and interceptors in charge of shooting down those recce planes.
IIRC the tests results u could use Nitrous oxyde for less than 10 minutes at full rpm but if you wished to preserve your engine and use it for a longer period you had to run it at a lower rpm. even in the later case temp rose slowly and 30-40 minutes was the aximum an engine could widthstand

Wilbus · « **Reply #12 on:** June 13, 2002, 04:38:54 AM »

Verm, I', not saying it didn't use GM1, just saying it doesn't make much sence to me

Would it be possible for you to send me the hand book? I REALLY want it and love all such information I can get

Please

Vermillion · « **Reply #13 on:** June 13, 2002, 12:08:37 PM »

Wilbus, I don't mind, but it may take me a while.

Just remind me repeatedly, and bug me about it all the time

Volume wise its pretty large and difficult to photocopy, so I have to do it in small batches at my job or they start to realize Im doing "non work" copying.

Otherwise its no big deal, just remind me in about a week when I get back to my home town.

Wilbus · « **Reply #14 on:** June 13, 2002, 12:49:32 PM »

Much appriciated Verm! I'll remind you