Re: Performance/Endurance of Bf 109 G-6 during aerial combat - questions for experts!!!
 

Hey thanks for that!

Which one can spin a bigger prop? The DB 605A or the DB 605AS? Many Thanks! I think this is a product of which makes more Torque?

Performance/Endurance of Bf 109 G-6 during aerial combat - questions for experts!!!
 

Hello Oberst

It is my understanding that the Bf 109 G-6 utilized the VDM 9-12087A whereas the Bf 109 G-6/AS was normally fitted with the VDM 9-12159A. The latter featured broader chord blades more suitable for the high altitude role that the AS powered type was envisioned for. I hope this helps.

Horrido!

Leo

Re: Performance/Endurance of Bf 109 G-6 during aerial combat - questions for experts!!!
 

Hello Leo!

Helps tremendously my friend! :D

From what I understand, Daimler Benz DB 605 ASM made 1800 PS with a maximum height of 7,8km 1944:
bei 2800 U/min in 0m Hohe.....: 1800PS
bei 2800 U/min in 6400m Hohe: 1500PS
bei 2600 U/min in 7800M Hohe: 1150PS

Re: Performance/Endurance of Bf 109 G-6 during aerial combat - questions for experts!!!
 

What would be the distance the P-38 would have to cover on the return trip?

Re: Performance/Endurance of Bf 109 G-6 during aerial combat - questions for experts!!!
 

The P-38 has about a 500-1000 mile combat radius (load dependant).

Re: Performance/Endurance of Bf 109 G-6 during aerial combat - questions for experts!!!
 

That is not the point. Kurürst asked:"BTW it would also be interesting to know how long Lightning could last over an enemy airbase and still return, preferably while disengaging at high speed."

So, one cannot answer this question without knowing the distance between that enemy base and one's own base.

Re: Performance/Endurance of Bf 109 G-6 during aerial combat - questions for experts!!!
 

Hi Bill!

You can find the details on my site: http://kurfurst.org/
You can find the relevant engine output (in all cases, static power) here: http://kurfurst.org/#engines

The tests themselves note the power regimes, so its a matter of putting 2 and 2 together.

But a quick recap - I am not sure what G types are you interested in, or is it cruise/max power, SL or rated alt?

Anyway, here it is:

G-2 (605A) - Mtt. calculation/official figures for early type:
max. 537 kph @ SL, 660 kph @ 7000m. 1310/1250 PS (static)*
max cruise. 600 kph @ 6000m, 1090 PS (rammed), 225 gram/PS/h fuel consumption

G-6 (605A) - flight trials:
510 kph @ SL, 625-630 kph @ 6700m. 1310/1250 PS (static)*
530 kph @ SL, 640 kph @ 6700m. 1475/1310 PS (static)
max. cruise. 480 kph @ SL, 585 kph at rated alt (ca 6 km), 1075 / 1080 PS

G-14/U4 (605AM w. MW boost)

568 kph @ SL, 665 kph @ 5000m. 1740/1700 PS (dynamic), datasheet, impossible to make out wheter calculation or test flight
max. cruise. 468 kph @ SL, 590 kph at rated alt (6 km), 1000 / 1080 PS (dynamic)

G-5/AS G-6/AS (605AS) - flight trials at 30 min rating:
507 kph @ SL, 654 kph @ 8300m. 1275/1150 PS (static)*

* at 30 min ratings

G-6/AS (605ASM w. MW boost)
560 kph @ SL, 675 kph @ 7500m. 1800/1500 PS (static), test flight
560 kph @ SL, 690 kph @ 6800m. 1800/1500 PS (static), another test flight
max. cruise. 480 kph @ SL, 610 kph at rated alt (8,4 km), 1030 / 1050 PS

G-14/AS (605ASM w. MW boost)
560 kph @ SL, 680 kph @ 7500m. 1740/1495 PS (dynamic), datasheet, impossible to make out wheter calculation or test flight
max. cruise. 460 kph @ SL, 620 kph at rated alt (8,4 km), 1000 / 1040 PS (dynamic)

G-10/U4 (early 605DM w. MW boost)

560 kph @ SL, 690 kph @ 7500m. 1750/1570 PS (dynamic), datasheet, calculation from August? 1944
max. cruise. 465 kph @ SL, 628 kph at rated alt (8,4 km), 1020 / 1030 PS (dynamic)

K-4 (early 605DM w. MW boost)
580 kph @ SL, 710 kph @ 7500m. 1750/1565 PS (dynamic), datasheet, possibly calculation from August 1944
max. cruise. 477 kph @ SL, 645 kph at rated alt (8,4 km), 1020 / 1030 PS (dynamic)

K-4 (605DB and DC w. MW boost)
DB : 595 kph @ SL, 710 kph @ 7500m. 1850/1600 PS (static), calculation from January 1945
DC : 607 kph @ SL, 710 kph @ 6000m, 710 kph @ 7500m.. 2000/1800/ca. 1600 PS (static), calculation from January 1945

max. cruise. probably the same or a bit better (DB/DC max. cruise power 1100/1140 PS).

Hope this helps.

Re: Performance/Endurance of Bf 109 G-6 during aerial combat - questions for experts!!!
 

Kurfurst - Thanks again and keep up the great website. SL and mid altitude high speed runs are best for triangulating parasite drag absent compressibility then gives me insight to the compressibility components at altitudes >20,000 feet

I was also really interested at the tip (propeller) compressibility questions in one of the P-51B-1/Merlin 1650-3 reports at 29000 critical altitude... and wondered if you have seen any German references to the same questions?

Bill

Re: Performance/Endurance of Bf 109 G-6 during aerial combat - questions for experts!!!
 

As I recall it, and it has been a while, compressibility (wave drag) effects are a function of Mach Number only. Can you explain why it should vary with altitude for this class of aircraft?

Re: Performance/Endurance of Bf 109 G-6 during aerial combat - questions for experts!!!
 

Graham - as you probably recall compressibility occurs around .5M and is a significant factor in Parasite drag even before boundary layer separation occurs and leads to wave drag.

The Speed of sound is purely a function of temperature, which is calculated as 33.42*Sqrt(T) where T=degrees Rankin when calculating M=1 in mph.

Hoerner references even the .54M speed of 380mph for the Me109G at 22000 feet with 1200 hp as entering into the compressibility range. As you well know 380mph is even a higher percentage at 29 and 35000 feet

Abbott and Doenhoff (from vague memory) have a chapter on drag rise =>5% as the trip point for describing the compressibilty flight regime and for a Mustang that region was in the .63M to.65M range - which is 441mph at 29000 feet for STP

For other a/c like a 109G/K or P-38 or P-47 or FW 190D that Parasite drag growth of 5% due to compressibility occurs at a lower speed than the 51, the P-38 being a wonderful example of quickly moving from compressibility to all out wave drag in seconds when entering a dive at 20,000 feet when already at near max speed.

You are probably thinking what I was referencing was more aong the lines of wave drag caused by boundary layer separation in the transonic to sonic flight regime range. I wasn't. I was commenting on Hoerner's comments in Fluid Dynamic Drag in section 14-7 on 'Aerodynamic Efficiency" ----> where influence of compressibility was about the same magnitude (6%) as induced drag at max speed (7%)

The reason I brought up Compressibility effects to parasite drag is to further reference Hoerner's discussion in the last paragraph of 14-7 when he illustrated the 109G drag build up in his Fluid Dynamic Drag example.

Folks that attempt to extract CDo from top speeds of fast WWII fighters at altitude should get a higher Total Drag component at 30,000 feet than SL because compressibility is adding incremental drag over that which is calculated assuming incompressible flow...an additional delta less significantly present at SL dash speeds.

I mentioned the transonic/supersonic tip speed study based on NAA/USAAF reducing data from the P-51B-1 w/1650-3 engine test runs at 441mph at 29000 feet. They were dealing not only with raw compressibility drag rise due to the wing/body but also propeller effects on drag rise.