Author Topic: Fuel economy test (Read 493 times)

Bozon12 · « **on:** October 09, 2001, 10:46:00 AM »

Yesterday i scrambled a G10 to kill a hog and 20k lanc near A8.
after killing the hog (i think ack finished him off but i got the credit) i fought the lanc and got it smoking & leaking fuel.
then just before landing the killing blow i run out of fuel! (took only 50% for better climb rate)
also I read on one of the posts that the f4u-1 has more range than the f4u-D.
So I decided to test it and ended up testing time runing on full power per 1/4 fuel load for most of AH fighters.

Method:
Offline, fuel multiplayer set on x10.
Load A/C with 1/4 fuel.
on runway, set throttle full.
start engine.
start clock when ignition "catches".
fly around with full throttle no wep.
mark time when engine stops.

Results:
multiplay result by 10 to get "real" runing time. this is time length relevant for CA where fuel mult. = 1.
devide CA result by 1.5 to get time for MA (fuel mult. = 1.5)
error estimated as 2 sec for measurment (used analog clock...

)
sorted by endurance:

Conclusions:
f4u-1 has significantly longer range than the D and -4. actually the -4 has poor range but as a powerfull E fighter can allow taking more fuel.
the zeke result was suprising (for me at least) with 4th place in this experiment (but probably inferior to other p47 p51-B models).
the poor old Hurrican has a VERY short endurance. when fuel is down to 25% it can hardly be used for base defence. for longer missions DT are must.
always thought the f6f had better endurance than f4u-D. guess i was wrong (I usually don't land the kittie...if you know what i mean

).
taking 50% with G10 for that interception left me with less than 16 min to complete it (lot of wep).

Remarks:
1/4 fuel is NOT 1/4 on fuel gauge for planes with several tanks.
for p51 it's a bit over 1/4 on LW/RW tanks and an empty AUX.
max range is also diffrent than runing time since cruse speed at full throttle is diffrent for every plane.

F4u-1 tank managment question:
the auto fuel managment consumes the main tank before wing tanks.
on other f4u model there are no wing tanks.
isn't it better emptying wing tanks sooner? leaving more mass near center of gravity? (for better roll rate)
or would it turn the plane unstable like aux tank in p51?

Bozon

[ 10-09-2001: Message edited by: Bozon ]

[ 10-09-2001: Message edited by: Bozon ]

[ 10-09-2001: Message edited by: Bozon ]

F4UDOA · « **Reply #1 on:** October 10, 2001, 10:20:00 AM »

Punt

Good questions.

Is anybody paying attention out there??

Zigrat · « **Reply #2 on:** October 10, 2001, 10:26:00 AM »

thats good info to have thanks

F4UDOA · « **Reply #3 on:** October 10, 2001, 10:55:00 AM »

Here is another question.

Why do the D9 and Spitty have longer range capabilty than the F4U-1D, -4 and F6F? The F4U-1D and -4 should have ranges of 1020miles and 1015miles with the Hellcat being at 1300miles. The Mossie is also extremely range limited?

Why then where the Spit and D9 limited in their range of operation?

ra · « **Reply #4 on:** October 10, 2001, 11:17:00 AM »

Something is definitely wrong with the Mossie endurance.

funkedup · « **Reply #5 on:** October 10, 2001, 12:09:00 PM »

nm

[ 10-10-2001: Message edited by: funkedup ]

Furious · « **Reply #6 on:** October 10, 2001, 01:17:00 PM »

F4UDOA,

Are you absolutely sure that those ranges were possible without drop tanks? I have read that the 1D's range drops to around 500 miles if the DTs are not used.

F.

F4UDOA · « **Reply #7 on:** October 10, 2001, 01:41:00 PM »

Furious,

Yeah I'm sure about the number. I actually have charts showing range for weight with and without DT's. The 500miles is radius. Even less with combat radius. The Navy has a formula they use to determine combat radius. It includes warmup, climbout, rondevous, combat with WEP and return flight. You can see the critera here.

For the full report with range here is the rest of the link.

F4U data

Furious · « **Reply #8 on:** October 10, 2001, 04:20:00 PM »

F4UDOA,

Thanks for the links, I am a big fan of the 1D.

I think the key to the differences in observed range may be the speeds involved. The Max ranges quoted for the 1D are achieved at apprx. 180 mph. What is the corresponding manifold pressure for 180 mph at alt? Probably substantially less than the 100% used for the Bozon's test.

I have no information what-so-ever reguarding relative fuel burn rates between the different fighters, so please don't think that I am advocating any one range as tested over another. Its just an interesting discussion.

F.

Bozon12 · « **Reply #9 on:** October 10, 2001, 08:54:00 PM »

As I said under "remarks", what was tested was the time lenghth for runing the engine at full throttle. this is NOT the same as range. The actual range depends also on the speed the A/C is traveling - which makes finding the range much more complicated.
for instance, max level speed usually increases with alt. so for long ranges it is better to climb slowly first and then traveling economicly (on miles/gallon terms) at a higher speed.
also, it may be wise not to travel at max speed with full throttle in order to get the max distance. the drad increases (at hi speed) close to liniarly with air-speed, therefore the rate of energy loss increases as the square. Meaning, you'll burn more fuel per mile gained.
In AH we fly most of the time at full throttle, so the nubers should give us a good estimation of the TIME we should expect to stay airborne.

I'm building a web page with info from experiments i've been doing. It's pretty much still under constraction and poor looking (never played with HTML before).
here is a first glimps of it:
Bozon's AH Flight Testing Page

Bozon

[ 10-10-2001: Message edited by: Bozon ]

F4UDOA · « **Reply #10 on:** October 10, 2001, 10:49:00 PM »

Heya's<S>

Furious, I know your your just discussing different possibilties. I'm not supporting any one theory myself. Just that the Navy had a range calculation that was based on a pretty realistic set of guidlines.

But I am not sure of the relative ranges of some of the other birds such as the Spit, 190D9, P-38 and P-47. They seem a little out of wack.

Bozon,

Great job with those test. Keep it up!! Here is a link to someone else who is doing the same thing.

NET ACES

Naudet · « **Reply #11 on:** October 11, 2001, 01:59:00 AM »

@F4U:

as Bozon mentioned, the test was run at full throttle, that equals combat and climb power setting in WW2, but range was normally calculated for most economic speed.

If we now compare range D9 and F4U-1D we would have to run the test at the most economic cruising speed.
It is quite possible that the fuel consumpiton of the F4U will be much lower at this point than of the D9.

Wilbus · « **Reply #12 on:** October 11, 2001, 10:39:00 AM »

Hey Boozon, nice info, you forgto the TA152 though, it's actually got more internal fuel the then P51 and, in the MA, it can fly for about 10 minutes longer with full tank.

I think many of the max ranges of planes in books, are with "best endurance", best hight with best enginge settings, in here Boozon, and the rest of us allmost runs at 100% wich might give us a false reading of the max range, all planes have a "best" settings for RPM and MAN. 1 190D9 might fly further on 100% power then an F4u does, the F4u however, might have a longer range if flown on the best engine setting for it, compared to the D9's best engine setting.

Bozon12 · « **Reply #13 on:** October 11, 2001, 08:47:00 PM »

Quote

Hey Boozon, nice info, you forgto the TA152 though

hehe, laziness has got nothing to do with memory...
but soon there will be results for all AH planes (buffs included) and will be posted on my web page.
calculating TRUE max range from takeoff is way too complicated to be done for all AH planes. hell, even for 1 planes i'll have to decide in what speed to climb, to what alt, and what is best manifold pressure in that alt to cruse...too many variables & unknown functions for them to maximize even roughly.
we don't need that.
next test will be done with 2/3 of max man. pressure. by gut feeling, ounce you're in a crusing position, this lowers the fuel consumption considerably but doesn't slow you down as much (sustained speeds). this is what I do when bringing a bird back home on fumes...
this is better than 100% pressure, but not best for all situations.

edited:
F4UDOA,
thx for the link, i found it on another post also.
it seems that the reason for the huge rage differences betwin F4U-1 and D is simply that D fuel capacity is much smaller! looks like they just eliminated the wing tanks on the D and 4 models...
i'll test that theory.
also by those reports, the 1 model is faster (350 military) than the D (343),
has smaller winload (38.3 vs 38.8 lb/sq.ft),
and only on climbrates the D was a bit better (1 min less to 20k)...
so i guess like with the p51B and D they took some preformance loss for that bubble canopy.

and just look at that -1 with F3.
was ever a plane so beautifully painted?

Bozon

[ 10-11-2001: Message edited by: Bozon ]

Bozon12 · « **Reply #14 on:** October 11, 2001, 09:52:00 PM »

just tested it,
F4u-1 run on full throttle with just the main fuel tank exacly like the D (well, was 2 sec diffrence).
so they really just eliminated the wing tanks on later models.
which brings me back to the question, if it isn't smarter to empty wing tanks before the main...

Bozon