Author Topic: Bf 109 G range and endurance (Read 13149 times)

Nashwan · « **Reply #30 on:** July 31, 2004, 10:51:20 AM »

I suspect that's a Merlin 61 engined Spit IX.

The best fuel economy on the Spit VIII with Merlin 66 was found to be at 23,000 ft, the figures I posted above are at 20,000ft. With the much higher critical alt of the Merlin 61, I suspect best economy would be obtained much higher, around 27,000 ft.

I doubt it's down to drag, if there was that much difference between the Spit VIII and IX, imagine the difference between the G2 you posted and the G6.

I'd say it almos entirely down to the difference between the Merlin 61 and 66. The Merlin 66 had a different supercharger and carb to the 61, so I don't think you can safely extrapolate the 66's performance from the 61.

Staga · « **Reply #31 on:** July 31, 2004, 12:46:38 PM »

Staga · « **Reply #32 on:** July 31, 2004, 01:08:18 PM »

From that chart:

5min climb = 6.66 liter/min= 33,3 liters
160min eco-cruise = 4.16liter/min= 666,7 liters
= 700 liters (400 internal+300 external)

niklas · « **Reply #33 on:** August 01, 2004, 05:12:51 AM »

Quote

Originally posted by MiloMorai
This is what Fw says on its range/endurance charts

1) Consumption from BMW specs +12.5% reserve
2) Avg. speed = ariithmetic avg. of outboard and inboard
3)Endurance includes climb and descent times
4) Range calculated(my bold) without (their underline) deductions for tactical requirements! (their !) Includes climb and descent distances.

Deductions made for warm-up, taxi, climb, descent, overshoot and reserves.

Where do you have this from?
niklas

MiloMorai · « **Reply #34 on:** August 01, 2004, 05:49:00 AM »

Quote

Originally posted by niklas
Where do you have this from?
niklas

From the Fw charts dated 23.12.43 headed Range and Endurance Calculations. 4 charts > clean, with WR21, with dt, with SC500

Says, Compiled by: Jauser Voigtsberger, at least that is what the signature looks like.

niklas · « **Reply #35 on:** August 01, 2004, 09:26:04 AM »

i know these charts very well, actually i sent the whole bunch to pyro recently.
Did you get them from him? Or.... ?

niklas

ra · « **Reply #36 on:** August 01, 2004, 09:47:12 AM »

Quote

Note that at the same fuel load, 150/154 gallon , the Mustang and the 109G`s specs are almost identical! 270/260miles and 1.55h/2h endurance (and the 109 has some extra drag from DT).

You are forgetting to take into account the power settings. The P-51 is cruising at 400mph, the 109 with DT at 350. To say that their range is almost identical is not totally accurate. The P-51 could throttle back to 350mph and drastically increase it's range. The Merlin is known to be thirstier than the DB, but the P-51 could cruise the same distance on 150 gallons as the 109G, but 50 mph faster. That's not much of a testimony to the efficiency of the 109.

ra

GScholz · « **Reply #37 on:** August 01, 2004, 12:52:10 PM »

Ra, I believe you are mistaken. Max. endurance is not at max. cruise speed, but you are right in that the P-51 had a higher cruise speed. Mostly because it could cruise at a higher altitude.

Edit: We are now of course talking about 109G-6 vs. P-51D. 109G-10/K-4 having very similar max. cruise speed at high altitude.

ra · « **Reply #38 on:** August 01, 2004, 08:52:12 PM »

I may be mistaken, but nothing about the numbers in the post can proove that. It lists the P-51 as having an endurance of 1hr 36min on 150 gallons. The P-51 burned around 50gph at economical cruise at 25K (even less at lower altitudes). With 150 gallons that would be 3 hours minus the fuel burned to get to 25K and back down. Even if it took 50 gallons to get to 25K and back down, that would leave 2 hours of fuel for cruise, not including the time for climbing and descending. So the 1hr 36min is for some higher power setting. We don't know what that setting is, so comparing these numbers to the 109 doesn't tell us much, especially because we don't know the power settings used for the 109 either. But we can be pretty certain 1hr 36min is not MAX endurance for a P-51 with 150 gal.

ra

MiloMorai · « **Reply #39 on:** August 02, 2004, 05:08:38 AM »

Quote

Originally posted by niklas
i know these charts very well, actually i sent the whole bunch to pyro recently.
Did you get them from him? Or.... ?

niklas

Should have include that they are in the Fw190A-8 Handbook published by Valkyrie Pub. in 1974.

Angus · « **Reply #40 on:** August 02, 2004, 07:48:58 AM »

Spitfire missions (mk V I think) could stretch up to almost 2 hrs WITHOUT drop tanks.
The P51 must have been able to cruise about 4.

Oh, BTW, how much does the DB drink at full power?

GRUNHERZ · « **Reply #41 on:** August 02, 2004, 07:50:27 AM »

Quote

Originally posted by Angus
Spitfire missions (mk V I think) could stretch up to almost 2 hrs WITHOUT drop tanks.
The P51 must have been able to cruise about 4.

You mean if the airframe did not fall apart first...

Angus · « **Reply #42 on:** August 02, 2004, 07:53:55 AM »

Hehe, yes, if the airframe was able to hold together.

Staga · « **Reply #43 on:** August 02, 2004, 09:08:23 AM »

Quote

Originally posted by Angus
Spitfire missions (mk V I think) could stretch up to almost 2 hrs WITHOUT drop tanks.
The P51 must have been able to cruise about 4.

Oh, BTW, how much does the DB drink at full power?

Bf109G-2 (DB605A): 480 liter/h 1.42ATA WEP
Spit IX (Merlin 61,63,66,67,266): 477 liter/h 12lb boost and 591 liter/h at 15lb boost.

Grendel · « **Reply #44 on:** August 02, 2004, 09:24:00 AM »

A sidenote:

In 1937 both a Messerchmitt 109 B (1660 HP) and a Spitfire I (2160 HP), both well trimmed and enhanced for record breaking, tried to win the world's speed record from Howar Hughes' H-1 record plane.

The Messerchmitt won it - even when it had 500 less HP. Quite telling about the excellent aerodynamics of the Messerchmitt fighter.