Author Topic: Dora experts ... (Read 5034 times)

Batz · « **Reply #60 on:** June 01, 2004, 04:08:44 AM »

Godo it seems I was incorrect that C3 was taken from the AUX tank to feed C3 injection.

From LEMB

Quote

From Janes:

"The pilot had a small push-pull control which operated two *****. The first **** opened an air bleed in the boost pressure regulator chamber, causing the regulator to open the butterfly throttle to provide +8.8 lb. boost instead of +5.5 lb. boost at sea level. The second **** opened a pipe line from the fuel pump to a spray nozzle fitted in the port air intake.

Quote

C3 would be injected or "bled off" from the fuel line, regardless of what fuel tank the 190 was already drawing fuel from.

I had thought that it used the same "plumbing" as mw50.

Batz · « **Reply #61 on:** June 01, 2004, 04:09:53 AM »

oops filter C O C K S and C O C K and C O C K

Crumpp · « **Reply #62 on:** June 01, 2004, 06:00:26 AM »

Go someplace else to try and pick up dates Batz.....

Crumpp

Crumpp · « **Reply #63 on:** June 01, 2004, 06:05:14 AM »

BTW Batz,

That Jumo Engine chart is pretty specific. It says B4 fuel. Your description of the boost system is correct except it did not use C3.

Crumpp

GScholz · « **Reply #64 on:** June 01, 2004, 07:49:57 AM »

Yes Crumpp, some Doras used C3 both as fuel and as a boost agent before MW50 was installed.

GODO · « **Reply #65 on:** June 01, 2004, 01:09:11 PM »

Crumpp, if you look at the chart you will find that:

1 - 2240 Ps are listed as 1st gear MW50 boost.
2 - 1900 Ps are listed as takeoff power (no more 1750 Ps).
3 - 1700 Ps are listed as climb power.
4 - 1100 Ps are listed as economical cruise.

The cockpit of common D9s had a throttle with only four zones:

Aus: off
Anlassen: normal (1100 Ps?)
Steigen: climb (1700 Ps?)
Start: takeoff (1900 Ps?)

And a black switch at the lower left side of the frontal control panel, near the fuel selector lever, to activate WEP (2240 Ps?)

Pyro · « **Reply #66 on:** June 01, 2004, 01:29:00 PM »

So if you calculate fuel flow off of that engine chart, what's it come out to in GPH?

GODO · « **Reply #67 on:** June 01, 2004, 02:20:43 PM »

Pyro, aside of fuel consumption, take into consideration that both 1900 (takeoff) and 2240 (WM50 boost) curves indicate 3250 rpm.

The blue numbers at the left indicate grams per PS per hour, and the bottom curves indicate fuel consumption based on rpms (Kraftstoffverbrauch). There is a single line for 3250 rpm, so we can asume 1900 Ps and 2240 Ps had the same fuel consumtion (2240 Ps should add MW50 consumption).

Lets use normal gasoline density as a reference for real B4 fuel density: 0.68 grams/cm3 at 20ºC

At 0k the line of 3250 rpm (1900Ps) indicates 270 grams/Ps/hour: 513000 grams/h -> 348.8 l/h (also aplicable to 3250 rpm + MW50: 2240 Ps) -> 92.73 Us Gals/h

At 0k the line for 3000 rpm (1700Ps) indicates 250 grams/Ps/hour:
425000 grams/h -> 289.0 l/h -> 76.35 US Gals/h

The worst case listed for 3250 rpm is 320 grams/Ps/h, so 320 * 1900 * 0.68 = 413.4 l/h = 108.9 Us Gals/h

AH D9 on WEP has 236 Gals/h, and seems way exagerated.

Pyro · « **Reply #68 on:** June 01, 2004, 02:57:25 PM »

Quote

Originally posted by GODO
[BAt 0k the line for 3000 rpm (1700Ps) indicates 250 grams/Ps/hour:
425000 grams/h -> 289.0 l/h -> 76.35 US Gals/h
[/B]

Your conversion is not correct. 1 US gallon should weigh 6lbs or very close to that. You are saying that 76.35 gallons weighs 936.96 lbs (425 kg) or 12.27 lbs per gallon.

425,000 g = 937 lbs. Each gallon weighs 6 lbs, therefore 937lbs = 156 gallons. 425,000 grams per hour = 156 gallons per hour.

HoHun · « **Reply #69 on:** June 01, 2004, 03:00:23 PM »

Hi Godo,

>There is a single line for 3250 rpm, so we can asume 1900 Ps and 2240 Ps had the same fuel consumtion (2240 Ps should add MW50 consumption).

Actually, the specific gasoline consumption at 3250 rpm with MW50 is given as separate curve - it's the one starting at 222 g/HPh at 0 km. (It's lower than the 3250 rpm curve without MW50 because water/alcohol consumption is not figured in, and because MW50 injection makes the engine run more efficiently.)

MW50 consumption is given in the upper part of the diagram as 150 L/h, along with what I guess means 690 L/h B4 fuel (40 GPH + 182 GPH). From the specific fuel consumption, it should be less than those 690 L, but though it's almost illegible that's the number I seem to make out.

>Lets use normal gasoline density as a reference for real B4 fuel density: 0.68 grams/cm3 at 20ºC

Hm, from what I've seen, the Luftwaffe never used such a low value in their aircraft weight charts. I could be wrong, though.

Regards,

Henning (HoHun)

Pyro · « **Reply #70 on:** June 01, 2004, 03:18:29 PM »

I've been looking at the wep consumption and I can't explain why that is so high in the game. Looks like that needs to be revised.

GODO · « **Reply #71 on:** June 01, 2004, 03:32:14 PM »

Hohun, we can use petrol density as reference: 850 grams/l.

0k 1900Ps 3250rpm 270grams/Ps/h: 513000 grams/h, 603 l/h, 159 Us Gals/h

0k 2240Ps 3250rpm 222grams/Ps/h: 497280 grams/h, 585 l/h, 154.56 Us Gals/h

Pyro, my mistake in the conversion, should be correct now.

Still far away from the current AH2 236 Gals/h on WEP.

For 3000 rpm 44.9" MP current AH2 is marking 156 Gals/h.
The chart shows 245 grams/Ps/h for 3000 rpm, that is 0k, 1700Ps, 245grams/Ps/h: 416500 grams/h, 490l/h, 129.46 Us Gals/h.

So, military power consumption may be off also by 26 Gals/h. Unless military consumption is ok but rpms are too low (1900 PS 3250 rpm instead of 1700 Ps 3000 rpm).

GScholz · « **Reply #72 on:** June 01, 2004, 03:44:08 PM »

WEP, SL, 222 g/PS/h, 2240PS
222*2240/1000 = 497.8 Kg/h = 679.1 L/h = 179.3 Gal/h

This consumption rate is fairly constant up to 250 meters, then it is gradually reduced to...

WEP, 750m, 224 g/PS/h, 2120PS
224*2120/1000 = 474.8 Kg/h = 648.8 L/h = 171.3 Gal/h

... this is gradually increased to...

WEP, 2500m, 233 g/PS/h, 2060PS
233*2060/1000 = 479.9 Kg/h = 655.5 L/h = 173.1 Gal/h

... it then increases a bit to...

WEP, 3750m, 255 g/PS/h, 1980PS
255*1980/1000 = 504.9 Kg/h = 689.5 L/h = 182.1 Gal/h

... then when MW50 gradually becomes ineffective the consumption increases to ...

WEP, 5200m, 305 g/PS/h, 1690PS
305*1690/1000 = 515.4 Kg/h = 703.9 L/h = 185.9 Gal/h

... from there on it drops linearly with alt to 8000m and beyond ...

WEP, 8000m, 324 g/PS/h, 1180PS
324*1180/1000 = 382.3 Kg/h = 522.1 L/h = 137.9 Gal/h

MIL power (3000 rpm) at SL should be ...

MIL, SL, 248 g/PS/h, 1700PS
248*1700/1000 = 421.6 Kg/h = 575.7 L/h = 152 Gal/h

... apart from the supercharger gear shift this power setting is more stable in fuel consumption over altitude up till rated altitude ...

MIL, 5200m, 280 g/PS/h, 1540PS
280*1540/1000 = 431.2 Kg/h = 588.8 L/h = 155.5 Gal/h

Now, I hope this is correct or else I've just wasted an hour of my life!

GScholz · « **Reply #73 on:** June 01, 2004, 03:48:57 PM »

GODO I used 732.22 grams per liter as reference weight of fuel. Is your number (850) more accurate?

GODO · « **Reply #74 on:** June 01, 2004, 03:53:09 PM »

0.85 g/ml is the base density for gasoil.
0.68 g/ml for gasolines.

Probably gasoil density is closer to B4 and light modern gasolines.