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Author Topic: Speaking of Me109G-Series FM Cd  (Read 10947 times)

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Ass Eagle

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Speaking of Me109G-Series FM Cd
« on: September 24, 2012, 07:01:14 PM »

A calc of the Bf109G-14/AS based on the Kurfurst site test reports for Nov 1944 which were uncorrected for compressibility and arrived at Total Parasite Drag coeeficient

The Gross weight comparisions = 286o Kg (6306 plounds) for the Bf109G-14/AS
 
Thrust = Drag.

For the Bf109G-14AS = .85*1850*550/(368*1.467) =1602.05 pounds, so is generating 12% more pure thrust before accounting for exhaust thrust.
 
The Bf109G-14/AS Total Thrust =1602.05*1.14=1826.34 pounds or 12% more thrust than the P51. The difference in Total Thrust will increase in favor of the G-14AS as altitude increases.
 
The Bf109G-14AS Wing Area = 172 sq ft, q=.5*.002376*(326*1.467)>>2 = 271.7psf

For Flat plate drag
 
Total Drag for the Bf109G-14AS= Cd*q*Wing Area S; D/q=1303/271.7=4.8 sq ft;

Total Drag Coefficient Cd=4.8/172=.028 at Sea Level, 368 mph, 1850hp
 
Cd Wet = 1303/271.7/590sq feet (from Hoerner Fluid Dnamic Drag=.00813 for G-14AS.
 
Cl Bf109G-14AS = (6306/172)/271.7 = .1349

Cdi = (.1349>2)/(3.14*.85*6.1)= .0011;

NOTE - debatable AR for Bf109G-14AS, should be lower based on b>>2/span but I'm using Hoerner's AR for the Bf109G
 
Flat plate Induced Di Coefficient for the Bf109G-14AS = 172*.0011 =0.1892 sq ft---> Parasite Drag = 4.8 -.189 = 4.61 Sq ft
 
So, recent calc hold the Bf109G-14AS at Total Drag Coefficient at .028 at max speed on the deck, with 1850 hp and 368mph (uncorrected for compressibility)

From data from different sources for SL to 25,000 feet I get .028-.031 for CDo

In the context of Drag Co-efficients - which are the guiding comparative drag values - All versions of the Mustang had a Much lower zero lift parasite drag and Total drag for all the flight regimes I have actually analyzed.  The Zero Lift Drag Coefficient, without compressibility corrections for high Speed/High Altitude runs, are about .016. The P-51B at 441mph/29000 feet/3000 rpm experienced both onset compressibility from about .62M and suspected supersonic tip effects on the propeller according to several test documents.  These runs had a calculated Parasite Drag (Zero Lift plus Compressibility) of ~.0175 CDp =======> ~ 66+ % of the Bf109 series.
 
Induced drag comparisons become tricky.
 
For level flight, same speed, same altitude.
 
When LE slats not deployed the Bf109 and you use the 6300 pound Weight I used above from the Bf109G-14AS Test 11/44,
 Ki= 1/2*rho*V>>2
 Si=172 sq ft
 
For a P-51B at 9600 (std full load without external tanks)
 kii = 1/2*rho*V>>2
 Sii=235 sq ft
 
CL= W/(K*S)
 For the abobe comparisons the Lift Coefficient reduces to the ratio of the wing area to the weight of each fighter.
 
Ergo -----------> Bf109G = 6300/172 = 36.6; P-51B = 9600/235 = 40.85 which is a ratio of wing loading.
 
For Induced Drag CDi= (CL)>>2/(pi*AR*e).  The Bf109G already has a lower CL, but it also has a higher AR (approx 1%) so for those conditions the Bf109G has a lower induced drag up to the range where the P-51 velocity exceeds the Bf109. The P-51 has to exceed the Bf109 velocity by about 5% at same altitude in comparison and the Induced drag is about equal.  At respective top speeds the P-51 will have both less Zero Lift Parasite Drag and Induced Drag.
 
If the comparisons switch to P-51A at 8400 pounds, 8400/235 = 35.75 ------->Lower CL, but Induced Drag for P-51A still extremely close to Bf109G-14AS considering Bf109G-14AS has better AR.
 
I haven't looked at Bf109G-10 or Bf109K-4 but each of those were heavier than the Bf109G-14AS so their Induced Drag Coefficient comparisons would be much closer than P-51
 
The P-51B/C/D also had better onset compressibility results at top speed/high altitudes than every Bf109, I don't mention the Allison engine P-51 simply because the engine performance at altitude was way below P-51B/C/D and only experienced limited compressibility effects - about the same as the Bf109G-14AS.

If I knew how to work Java I would fix very little that needs it, but I don't soooo....
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Paulo Hirth

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Re: Speaking of Me 109G-Series FM Cd
« Reply #1 on: September 25, 2012, 01:44:13 AM »

 Very interesting, would cool if possible fly optional FMs based in real test.
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Ass Eagle

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Re: Speaking of Me109G-Series FM Cd
« Reply #2 on: September 25, 2012, 09:52:47 AM »

Yes, very cool if could!

Documents like these examples for help:

This is for F-4


This is G-series cowl


This is G-series wing


Help to no end. From docs like these, and some mathematics, along flight comparative flight data from the source ( not from captured planes ) one get get true sense of what these planes are capable of.

Comapare to LA-7 the 109 is on par. Not the Ubber God-like manuverability of the LA-7. Same with P-51, especially at low speed where -51 is cannon fodder. Or -47 which is opposite of -51.
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Ass Eagle

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Re: Speaking of Me109G-Series FM Cd
« Reply #3 on: September 25, 2012, 01:45:21 PM »

For DB 605 AS engines, which seem to be 'lacking' against older Merlin Engine in P-51B/C/D, I like to see this:

Just like varianten of DB605AS engines:

~ Daimler Benz DB 605 ASC 2000ps December 1944

 - bei 2800 U/min in     0m Höhe: 2000ps
 - bei 2800 U/min in 4 900m Höhe: 1800ps
 - bei 2570 U/min in     0m Höhe: 1400ps
 - bei 2570 U/min in 6 800m Höhe: 1285ps
 - bei 2300 U/min in     0m Höhe: 1260ps
 - bei 2300 U/min in 6 500m Höhe: 1200ps
 - Volldruckhöhe     6 800m
 
 ~ Daimler Benz DB 605 ASM 1800ps August 1944

 - bei 2800 U/min in     0m Höhe: 1800ps
 - bei 2800 U/min in 6 400m Höhe: 1500ps
 - bei 2570 U/min in     0m Höhe: 1250ps
 - bei 2570 U/min in 7 800m Höhe: 1155ps
 - bei 2300 U/min in     0m Höhe: 1020ps
 - bei 2300 U/min in 7 100m Höhe: 1040ps
 - Volldruckhöhe     7 800m
 
 ~ Daimler Benz DB 605 ASB 1850ps August 1944

 - bei 2800 U/min in     0m Höhe: 1850ps
 - bei 2800 U/min in 6 000m Höhe: 1600ps
 - bei 2570 U/min in     0m Höhe: 1430ps
 - bei 2570 U/min in 6 900m Höhe: 1285ps
 - bei 2300 U/min in     0m Höhe: 1290ps
 - bei 2300 U/min in 6 500m Höhe: 1200ps
 - Volldruckhöhe     6 900m
 
 Das Triebwerk Daimler Benz DB 605 ASM entsprach dem Ausgangsmuster DB 605 AS, wurde jedoch im Gegensatz zu diesem zur Verbesserung der Start und Notleistung mit dem Sonderkraftstoff C 3 und zusatzlincher Wasser Methanol-Einspritzung geflogen (MW 50).

*Notice performance and Altitude tests of Daimler Benz DB 605 ASM 1800ps August 1944 ;)
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Ass Eagle

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Re: Speaking of Me109G-Series FM Cd
« Reply #4 on: September 27, 2012, 02:21:30 PM »

But I will say one thing though, After reviewing my Great Uncle flight logs & reports (ME109G-14AS), and reviewing a complete evaluation of JG-301 captured P-51B CK+T9, my modified G-14AS&DB 605 ASM fmd & emd files now perform as should. No longer -51B's runaway & climb out of sight.  And now much more even match with P-51D historically. But at certain altitude, man -51D is tuff! Just like history ;)

~ Optimum Altitude now achieved - 6400m cruise/economy
~ Optimum Speed now achieved - 680km/h (420mph) at 7100m
~ Optimum climb rates now achieved - 1478m/min at only 1829m
~ Optimum dive Speed now achieved - 900km/h

Now this is without touching any other planes. Which I'm sure are pretty good flight models. Now to look at the 'super' LA7 & Jak9 to see what makes them tick.
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FANATIC MODDER

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Re: Speaking of Me109G-Series FM Cd
« Reply #5 on: October 05, 2012, 02:07:54 AM »

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FANATIC MODDER

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Re: Speaking of Me109G-Series FM Cd
« Reply #6 on: October 05, 2012, 02:34:22 AM »

Thanks very much for you info, this is very much appreciated.

The above engine chart is slightly off-topic, but I thought about inducing it since there is talk about the G-14/AS

Now I should explain the motor performances a bit:

-A : G-1/2/3/4/5/6

-AM: Late and rebuilt/modernised G-6 and G-14

-AS: G-6/AS

-ASM/ASB/ASC: G-14/AS

-D-2: Not in production

-DB/DC: G-10

As you see from the engine comparisons the late G-14/AS with the ASC engine, produced from Dec. 1944 until the end of the war and the very late 109 to be put in mass scale production,  it may be the best 109 variant of all.

The DC engine has an alt. advantage of 1.100 m but is below 30hp at sea level and if we consider all parameters like the greater commonality with the G-6 than G-10/K-4, the possibilty of using existing G-6 airframes etc. then the advantages of the -DC engine and the other various refinements of the K-4 seem marginal.


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Ass Eagle

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Re: Speaking of Me109G-Series FM Cd
« Reply #7 on: October 05, 2012, 08:01:03 AM »

No worries, the engine specs are very much relevant in this thread. Heres two of many that I have:





The 2000ps monster 1.98ata was tested as early as December 1944, but wasn't 'officially' approved until Feb, 1945. Mainly do to a
inadequate sparkplug. However, this simple modification to 1.98ata may have been done since late 44 by ground crews. A minor adjustment on the barometric diaphram on the supercharger, some new plugs, and you got 2000ps. A warning was CLEARLY issued late in 1944 for ground crews NOT to do this modification. But as with anything, sometimes ignored. Two big offenders of this was JG 53 & JG 300.

Anyways I tested my new modified FM for a while now, and its pretty much on par with the historical data. I'm very happy with it :)

Horrido!
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FANATIC MODDER

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Re: Speaking of Me109G-Series FM Cd
« Reply #8 on: October 05, 2012, 11:13:27 AM »

That's again very interesting the info that you shared with us.  So it's safe to assume that the G-14/AS produced since the first days of december 1944 had an ASB engine? Which is not a bad thing at all, since it was hardly inferior from the 605DB.

Do you have any accurate info about the whole production timeframe of the late 109 variants?

So we have as far as I know

G-6 Dec. 1942 - Aug. 1944?

G-6/U2 Early 1943 - Late 1944????  ------ DB 605A/GM1 -- produced at least until the start of production for G-14/ASM

G-6/AS Feb. 1944 - Aug. 1944?

G-14 May 1944 - Dec. 1944?

G-14/ASM - Aug. 1944 - Dec. 1944?

G-14/ASB - Dec. 1944 - May 1945

G-14/ASC - Feb. 1945 - May 1945

G-10 - Nov. 1944 - May 1945

K-4 - Oct. 1944 - May 1945

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Ass Eagle

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Re: Speaking of Me109G-Series FM Cd
« Reply #9 on: October 05, 2012, 11:30:06 AM »

In December 1944 I've seen both G-14ASB engines and G-14/ASC(M) engines. Labeled as B4/C3/ & 100 octane fuels.

Me 109G-14/G-14AS
Erla-Leipzig

460322 to 460371
460645 to 461378 - Bf109G-14/AS
460372 to 460644 - Bf109G-14 & Bf109G-6/MW
461379 to 461999 - Bf109G-14
462632 to 463006 - Bf109G-14
463110 to 463248 - Bf109G-14
464047 to 464660 - Bf109G-14
464814 to 464924 - Bf109G-14
465250 to 465982 - Bf109G-14

WNF

510000 to 510010 - Bf109G-14/AS
510640 to 510999 - Bf109G-14/U4 & Bf109G-6/U4
511000 to 511905 - Bf109G-14/AS
512115 to 512650 - Bf109G-14/AS

Mtt-Reg

780301 to 780880 - Bf109G-14/AS Sept-Oct'44
780881 to 780999 - majority Bf109G-14/AS to Aug'44
781000 to 781210 - Bf109G-14/AS from Sept'44
781220 to 781999 - Bf109G-14/AS & unknown number Bf109G-14
782000 to 782280 - Bf109G-14/AS & unknown number Bf109G-14
782281 to 782430 - Bf109G-14/AS from Sept'44
782750 to 783999 - Bf109G-14/AS from Sept-Oct'44
784001 to 784200 - Bf109G-14/AS from Sept'44
784730 to 784999 - majority Bf109G-14/AS finished Sept'44
785000 to 785145 - majority Bf109G-14/AS from Oct'44
785146 to 785170 - Bf109G-14/AS from Oct'44
785175 to 785200 - majority Bf109G-14/AS from Nov'44
785600 to 785725 - majority Bf109G-14, Nov'44
785726 to 785999 - majority Bf109G-14/AS, Nov-Dec'44
786300 to 786540 - majority Bf109G-14/AS, Jan'45
787445 to 787495 - majority Bf109G-14/AS, Feb'45


VW+HL Messerschmitt Bf109G-14/U4 W.Nr.413598 W.Nr.413598                 
VW+HM Messerschmitt Bf109G-14 W.Nr.413599 W.Nr.413599                 
VW+HN Messerschmitt Bf109G-14 W.Nr.413600 W.Nr.413600                 
VW+HO Messerschmitt Bf109G-14 W.Nr.413601 W.Nr.413601 black 7 8./JG 1

Me 109G-10
130000 – 130500 ~ Mtt-Regensburg G-10 - small main/long fixed tailwheel
150700 – 151000 ~ Erla G-10
151500 – 152000 ~ Erla G-10
490000 – 490800 ~ Erla G-10 - many were fitted with DB 605/AS - small main/long fixed tailwheel
491000 – 491600 ~ Erla G-10 - small main/long fixed tailwheel
610300 – 610600 ~ WNF G-10
610900 – 611000 ~ WNF G-10
611900 – 612000 ~ WNF G-10
612700 – 613000 ~ WNF G-10
613000 – 613300 ~ WNF G-10
770000 – 770400 ~ WNF G-10 - majority equipped with Rb50/30 camera
770900 – 771000 ~ WNF G-10 - majority equipped with Rb50/30 camera
771000 – 771200 ~ WNF G-10 - majority equipped with Rb50/30 camera
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FANATIC MODDER

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Re: Speaking of Me109G-Series FM Cd
« Reply #10 on: October 05, 2012, 12:20:59 PM »

Thank you very much for this data.

So a small number of the Erla G-10 had the -A series engines (so, in fact, not so much of a G-10...)

G-14 (with the -AM engine) was terminated (so the 109s with the 'classic' gun bulges) in November 1944. Still, it seems like the vast majority of the produced 109s from Aug 1944 until the end of the war were G-14/AS. Any production figures?
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razor1uk

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Re: Speaking of Me109G-Series FM Cd
« Reply #11 on: October 05, 2012, 12:22:40 PM »

Sounding cool so far Ice Eagle/Horrido et al (and friends), 8) may the flight testing continue towards greater/closer representation of realism :)

Just wondering hyperthetically, if for instance when your squadron gets very kow on A/C if you'd might have slightly higher chance of mechanical problems or slightly reduced power/reliability as the ground crew are overworked trying to get damaged A/C upto service strenght? Apologies if this is an wrong idea...
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