Author Topic: how about MW-50 and or GM-1 for the Dora? (Read 1211 times)

Naudet · « **Reply #15 on:** June 05, 2002, 02:18:56 PM »

Ok i found my prove that a 1900PS power setting using MW50 didnt exist.
This also means that curve number 4) definitivly delivers 2100PS.

Look at this, this is an british intelligence report about a D9 captured in Jan '45, this D9 had a german handbook abort:

1900PS uses 2,8 lb/sq in boost pressure

2100PS uses 4lb/sq in boost pressur and MW50

if know one could convert "lb/sq in" into "ata" we could see if 4 lb/sq in = 1,8 ata

if that is so, curve 4) will be with 2100PS

Naudet · « **Reply #16 on:** June 05, 2002, 02:20:02 PM »

dam forgot to attach picture

niklas · « **Reply #17 on:** June 05, 2002, 04:58:44 PM »

curve 3 is for 2400-2600PS

Naudet, what was the date of the chart? (Datum??)

niklas

HoHun · « **Reply #18 on:** June 05, 2002, 05:26:48 PM »

Hi Niklas,

>curve 3 is for 2400-2600PS

I'd appreciate if you'd explain how you arrived at this - flawed -assumption.

Just compare the Fw 190D-9 to the P-51H or the La-7 - these two aircraft didn't need 2500 HP to exceed 600 km/h by a fair margin (in fact, the La-7 did with less than 2000 HP). Even without doing the math, that the D-9 reaches 640 km/h on 2100 HP is entirely within reasonable expectations.

However, as I already pointed out, I've matched the Jumo 213A's power graphs with the Fw 190D-9's speed graphs with good precision.

Regards,

Henning (HoHun)

Naudet · « **Reply #19 on:** June 06, 2002, 01:56:56 AM »

Henning,

do you remember your Excelchart to calculate D9 performance?

I still have it, and for the fun i tried to hit the SeaLevel speed for curve#3.

I started with the highest JUMO213 poweroutput i know: 2240PS

And guess what, the resulting speed was a near perfect match with the SL speed of curve #3.

If i consider the used propeller efficiency in that excelchart not totaly off, i would say curve#3 is for something between 2200-2300PS.

About P51 and LA7, they exceded 600 km/h by a wide margine with 2000 HP or less.
The LA7 on the deck and the P51 very high up.
But if you just mean SL speed, don't forget the P51 was intended for high altittude usage and the charger gears were set according to this.

I don't doubt that the D9 was up to the end of the war able to outrun any allied fighter (beside the tempest) on the deck, butespecially the LA7 was not far of. The most decisive factor with the LA7 might have been the very varying production quality.

HoHun · « **Reply #20 on:** June 06, 2002, 09:57:42 AM »

Hi Naudet,

>do you remember your Excelchart to calculate D9 performance?

>I still have it, and for the fun i tried to hit the SeaLevel speed for curve#3.

I remember that you have an out-dated version of my Excel sheet :-)

Still, try to feed the entire power graphs into the data sheet instead of just a single data point, and you'll end up with speed graphs that look much like those on the Focke-Wulf chart. The fastest, generated with the 2100 HP graph, will look just like curve 3. It's simply impossible to generate something like curve 4 from the 2100 HP or 2200 HP power curves, but with the 1900 HP power it works quite well. The 2100 HP power curve, by the way, results in a shape just like that of curve 3.

>About P51 and LA7, they exceded 600 km/h by a wide margine with 2000 HP or less.
The LA7 on the deck and the P51 very high up.
But if you just mean SL speed, don't forget the P51 was intended for high altittude usage and the charger gears were set according to this.

Remember I'm talking about the P-51H :-) It had much more power than the P-51D and was much faster, too. The P-51H had about 2200 HP, which coincedes well with the Fw 190D-9's power, so it's not surprising that a 2100 HP Dora is in the same region of performance as the P-51H.

Regards,

Henning (HoHun)

Kweassa · « **Reply #21 on:** June 06, 2002, 11:13:22 AM »

I seem to recall someone mention the 190A-8 should have MW-50 set on it. Is this true?? Currently, our AH A-8 is slower in maximum speed than the 190A-5, and climbs worse, too.

HoHun · « **Reply #22 on:** June 06, 2002, 01:03:09 PM »

Hi Kweassa.

>I seem to recall someone mention the 190A-8 should have MW-50 set on it. Is this true?? Currently, our AH A-8 is slower in maximum speed than the 190A-5, and climbs worse, too.

I don't think the Fw 190A-8 was ever used with MW50.

They used liquid fuel injection, though, achieving a similar effect, rising 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 equal equipment probably came close in climb rate.

(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. This example might have been competetive with the A-5.)

The Fw 190A-8 apparently used GM-1 injection, however, but this was only beneficial above 8 km.

Regards,

Henning (HoHun)

niklas · « **Reply #23 on:** June 06, 2002, 01:18:44 PM »

Quote

Originally posted by HoHun
Hi Niklas,

Just compare the Fw 190D-9 to the P-51H or the La-7 - these two aircraft didn't need 2500 HP to exceed 600 km/h by a fair margin (in fact, the La-7 did with less than 2000 HP). Even without doing the math, that the D-9 reaches 640 km/h on 2100 HP is entirely within reasonable expectations.

Regards,

Henning (HoHun)

La-7 did reach over 600km/h after the war, during 44 it peaked out at 590-595. Late war performance claims from russia are vasty exaggerated imo. yak3 570-580km/h with 1250PS at ground tststs....
P51D reached also 15k or so with 1st gear though v1650 should peak out at 10k (critical alt 1st gear only 6k non-rammed) - so they had a good day. I´ve seen an english test where the P51D was 15-20mph slower than the source AH uses.

German claims and performance calculations were very reasonable. They were quite often reached or sometimes exceeded when they were captured.

For example in the range claims for the 190 there is a 12.5% safety factor included (fuel consumption factor). And 50liter were considered to be not usable at all (warming up, remaining at the botoom). Now it looks like the 190 had a poor range or had a thursty engine, but in real life you could be sure that you reach your target and make it home even with troubles on the way.

niklas

Naudet · « **Reply #24 on:** June 07, 2002, 06:20:50 AM »

Outdate version?

What did you modify and can you sent the new one to me via email? (naudet@blackadders.de) Would be nice to have the newest version and a little describtion of the changes.

Thx in advance

Kweassa · « **Reply #25 on:** June 07, 2002, 07:50:04 AM »

Quote

I don't think the Fw 190A-8 was ever used with MW50.

They used liquid fuel injection, though, achieving a similar effect, rising 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 equal equipment probably came close in climb rate.

(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. This example might have been competetive with the A-5.)

The Fw 190A-8 apparently used GM-1 injection, however, but this was only beneficial above 8 km.

- by Hohun

So, then would it be safe to assume in general the 190A-8 is truly slower than the A-5? I've got pretty much faith in the HTC charts, but I seem to keep bumping into data that suggests the 190A-8 was about 20~30kph faster than the A-5.

MANDOBLE · « **Reply #26 on:** June 07, 2002, 09:30:12 AM »

Quote

Originally posted by HoHun
[BThey used liquid fuel injection, though, achieving a similar effect, rising the boost from 1.42 ata to 1.58/1.65 ata for some extra horsepower.[/B]

Didnt the 190A5 use the same injection system?

fats · « **Reply #27 on:** June 07, 2002, 10:34:38 AM »

--- Naudet: ---
1900PS uses 2,8 lb/sq in boost pressure

2100PS uses 4lb/sq in boost pressur and MW50

if know one could convert "lb/sq in" into "ata" we could see if 4 lb/sq in = 1,8 ata
--- end ---

Just sure you understod ( I understod you? ) the the Brittish text correctly.

The boost is increased by 2.8 or 4 lb/sq on top of what ever the boost pressure was before the activation of either mechanism. The boosts are not 2.8 and 4 lb/sq.

// fats

HoHun · « **Reply #28 on:** June 07, 2002, 12:04:50 PM »

Hi Kweassa,

>So, then would it be safe to assume in general the 190A-8 is truly slower than the A-5?

Vermillion has provided some excellent charts that show that the Fw 190A-8 with standard 1.42 ata boost is truly slower than the Fw 190A-5 tested in the USA.

With 1.58/1.65 ata boost, the Fw 190A-8 is faster below each supercharger stage's full pressure altitude and slower above it.

The critical question is when the Fw 190A-8 was equipped with the boost increase. I think Niklas has done some research on that topic.

It's also not clear how many A-8s were converted, but the absence of a Rüstsatz or Umbau designation could mean that it was seen as a regular engine modification routinely applied to all aircraft, but that's speculation.

>I've got pretty much faith in the HTC charts, but I seem to keep bumping into data that suggests the 190A-8 was about 20~30kph faster than the A-5.

This would be interesting to see. I've to admit that I don't quite understand the A-8's loss of speed compared to the A-5. Weight doesn't suffice as explanation, it must be drag, but I can't see where all that drag is coming from. Maybe an additional set of figures would provide enough information so we could sort it out :-)

Regards,

Henning (HoHun)

HoHun · « **Reply #29 on:** June 07, 2002, 12:13:00 PM »

Hi Mandoble,

>Didnt the 190A5 use the same injection system?

The Fw 190A-8 had a special system for injecting liquid fuel into the supercharger air intake for improved charge cooling, resulting in an increase of the amount of oxygen in the charge. This system was only introduced in 1944 as far as I know.

Accordingly, the Fw 190A-5 did not have this "C3" injection system (named for the Luftwaffe's designation for 96 - 100 octane fuel). Of course, the Fw 190A-5 and A-8 both used the same injection pump for normal operation, so referring to the standard injection system, you're right.

I used ambigous terms there, I'm sorry! Hope I've managed to clarify it now :-)

Regards,

Henning (HoHun)