Bf 109 G range and endurance

[VO101_Isegrim]

Originally posted by Karnak
Less drag than a P-51B/D or Mosquito?  I have never heard that.  I understood that those were the two most aerodynamically clean piston engined aircraft of WWII.  A feature of both was high cruise speed.

Yet this document would seem to indicate that the P-51D was no longer ranged than the Bf109G-2.

The P-51 was longer ranged of course. It carried more than 2 times as much fuel. But on similiar loadout, the range would be very simliar.

Bf 109`s cruise speed was high as well, 600-650 km/h at altitude from 109F to 109K. Similair that of the P-51s. 109s had very little drag, no doubt, just check their SL speeds and the power required to reach it. Messerschmitt designed the fighters profile as small as possible, which guaranteed minimal drag.

Reminds me of the old story about Heinkel and Messerscmitt arguing against each other. Heinkel states that he builds aircraft that are of aerodynamic perfection.

Messerscmitt  replied : Well,  I build fast ones.

[VO101_Isegrim]

Originally posted by Karnak

I am still skeptical of the 1,250 mile claim.  I'd bet it was a calculated number based on a much shorter flight test and doesn't include the fuel consumption used for the climb to 18,000ft.

Well, you can calculate that, too, climbing to 18000ft wouldn`t take even 4 mins, at Kampleistung, with a consumption of 380 to 400 liters/hour. That`s about 25-30 liters spent on climbing, on which some distance was covered as well, plus some extra for warmup etc.

All in all, in the worst case scenario I think about 50 liters/10 gallons would be spent on getting at 18k ft.

The rest 144 gallons would be enough for another 1310 miles at the given 9.1gal/mile rate, so this chart is probably containing some reserves as well !

Of course this is for an econical cruise, with lots of combat, lots of high power applied, the range would be reduced quickly. But this is just as well, or even more so true for the other fighters as well.

[GScholz]

Originally posted by Karnak
Less drag than a P-51B/D or Mosquito?  I have never heard that.  I understood that those were the two most aerodynamically clean piston engined aircraft of WWII.  A feature of both was high cruise speed.

The 109 was not as clean as the P-51, but it was much smaller. The P-51 even with its better drag coefficient had more drag than the 109 because of its size. Drag coefficient is a size independent value and needs to be multiplied with the reference area of the airplane, usually wing area.

109 Drag coefficient X 109 size = less drag than P-51 drag coefficient X P-51 size.

Originally posted by Karnak
I am still skeptical of the 1,250 mile claim.  I'd bet it was a calculated number based on a much shorter flight test and doesn't include the fuel consumption used for the climb to 18,000ft.

Yes that is a distinct possibility. I don't know whether other aircraft usually have fuel spent on climb calculated in their range estimates (because they are all estimates that does not take into account wind, temperature, humidity etc.).

[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.

[Karnak]

According to that document the P-51D without drop tanks totaling 269 US gallons and the Bf109G-2 with a drop tank totaling 154 Imperial gallons would have had very nearly the same range.


As to the deck speed, well, altitude and engine performane and drag all come into play.  The Spitfire Mk XIV's engine is rated at 2,050hp, but I don't know what it was producing at SL.  The P-51D's engine, IIRC, was about 1,700hp, but once again I don't know what it was at SL.  Given the DB605 on the Bf109G-10/K-4 produced (IIRC) about 2,000hp it is likely that it was producing significantly more power at SL than the P-51D's Merlin and yet their speed is nearly identical.  The Spitfire Mk XIV and Bf109G-10/K-4 have very similar top speeds at higher altitude, 448mph and 452mph respectively.

It is hard to do a direct comparison.

[GScholz]

Ok so the estimated range (calculated with standard atmosphere) includes warm-up, taxi, climb, descent, overshoot and reserves?

[Nashwan]

The 1,250 miles seems, um, highly suspect. Very highly suspect. The DB605 would have had to have been insanely more fuel efficient than the RR Merlin in order for that to be possible.
------------------------------------------

Yep, it was, plus the Bf 109 was less draggy so it could travel faster with the same power = better milage.

From the Australian archives via Ring's site, range tests of a Spit VIII with Merlin 66:



(Ferry condition simply means a 90 gallon tank was fitted, the weight has been averaged between full fuel and external tank and no fuel)

BTW, the Spit VIII in this example is carrying 123 gallons internal and 90 gallons external, and can achieve up to 10 ampg.

[GScholz]

Originally posted by Karnak
It is hard to do a direct comparison.

That's so true.

On the P-51 vs. 109K at SL: At high speed parasitic drag becomes the dominant factor, at low speed induced drag is the dominant factor. There are so many variables.

[Karnak]

MiloMorai,

Yes, the de Haviliand stuff I have also says that.  The document linked at top does not.  That is why I am wondering about it.

[MiloMorai]

Originally posted by Karnak
MiloMorai,

Yes, the de Haviliand stuff I have also says that.  The document linked at top does not.  That is why I am wondering about it.

Would be nice to see the original German doc.

Right now it is hard to tell if the doc in the link is German or British. The doc number seems to be a British source, so one would have to question the validity of the numbers.

[MiloMorai]

This chart from Zenos, of bad quality, gives some ranges for a P-51D. Only pg 2 is posted.



Anyone have both pages and of a much better quality?

[GScholz]

Say, haven't we done this before? I vaguely remember a 400+ monster thread a few months back where we discussed EVERYTHING with special attention on fuel efficiency and drag.

[VO101_Isegrim]

According to that document the P-51D without drop tanks totaling 269 US gallons and the Bf109G-2 with a drop tank totaling 154 Imperial gallons would have had very nearly the same range.

Indeed.

AIR 15/741 is a very nice comparion for the subject, both range and max. cruise datas (though 109G cruise appears to be very slightly lower than German specs for G-6 - maybe based on the G-6/U2 of AFDU?).


It gives the following data :

Spit XIV

Fuel : 109 gallon (int)
Max. cruise speed : 380 mph /25k
Radius of action / enduracne  : 125 miles / 50 minsFuel : 109

Fuel : 199 gallon (int+1x90)
Max. cruise speed : 360 mph /25k
Radius of action / enduracne  : 260 miles / 1 h 55m

(Spit 21 is very slightly better)

Mustang III (w/o rear fus. tank)

Fuel : 150 gallon (int)
Max. cruise speed : 400 mph /25k
Radius of action / enduracne  : 270 miles / 1h 36min  mins

Fuel : 275 gallon (int+2x62.5gallon)
Max. cruise speed : 350 mph /25k
Radius of action / enduracne  : 450 miles / 3h

Me 109G
note: must be G-2 or even more so by the specs, a normal G-6 w. DB 605A

Fuel : 88 gallon (int)
Max. cruise speed : 360 mph /20k
Radius of action / enduracne  : 130 miles / 1h

Fuel : 154 gallon (int+1x66 gallon DT)
Max. cruise speed : 350 mph /20k
Radius of action / enduracne  : 260 miles / 2h


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).

Again, the best thing is the standards are the same, so the values are comparable.

Another British intelligence doc, date 15th Feb 1945, states the following ranges obtainable (no Mustang specs, or cruise speeds, unfortuntely) .

"Still Air range "

Spit XIV :

-460 miles w. 112 gallons (int. only)
-850 miles with 202 gallons (int. + 90 gall DT)

Spit XVI, Merlin 266 (should be identical to Spit VIII and IX)

- 434 miles w. 85 gallons
- 980 miles w. 175 gallons

FW 190A

- 500 miles w. 110 gallons (internal)
- 800 miles w. 176 gallons (int. + 1x66gallon DT)

Me 109G

-615 miles w. 88 gallons
-1000 miles with 154 gallons (int. + 1x66 gallon DT)

Again, the best thing is that all data comes from the same sheet, so it`s comparable.


The 605/Bf 109s duo had extremely good fuel effiency, no doubt.
I wonder what range those recce 109G-4s had, which caried duel 66 gallon DTs, one under each wing. I would recon somewhere around 1700 miles would be fit for them, at economic cruise. Definetely those were the longest ranged 109s, followed by the K-4 (which were the cleanest of them all, and had a dual purpose extra 115 liter fuel tank in the rear, plus could carry the same droptank as the others), the the later, high altitude 109Gs and so on, linearly back in the timeline, with tiny difference between the G-2/G-4 and the early G-6s.

[VO101_Isegrim]

Originally posted by Nashwan
From the Australian archives via Ring's site, range tests of a Spit VIII with Merlin 66:

http://www.onpoi.net/ah/pics/users/282_1090515978_spitviiirange.jpg

(Ferry condition simply means a 90 gallon tank was fitted, the weight has been averaged between full fuel and external tank and no fuel)

BTW, the Spit VIII in this example is carrying 123 gallons internal and 90 gallons external, and can achieve up to 10 ampg.

I wonder why even British documents give the Spitty`s 20-30% shorter ranged than 109s on the same amount of fuel then?

Which appears to be quite logical, given the Spitty always required more HP to haul itself around at the same speed than the Hundredneun, and Merlin`s specific fuel consumption was not so good as the DBs.

Perhaps these are "dry tank figures", ie. no reserves? Do you know the other details?

BTW, this is also from those Australian archieves :

http://www.x-plane.org/users/isegrim/FvsF/9-MkVIIIdive-restriction.jpg
http://www.x-plane.org/users/isegrim/FvsF/7-diveprohibition.jpg

I wonder if Guppy/Dan knows more about this, he said something similair about Spits over Normandy, iirc loosing wings when bombs were left attached in dive bombings.

[VO101_Isegrim]

Found this at Ring`s site, standards at which the Spitfire IX`s range and endurance was deducted.



Wonder why is there such a huge difference between the Mk IX and the Mk VIII figures posted by Naswhan?