Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: DweebFire on May 27, 2007, 04:38:11 PM
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Hello all
Not sure exactly how much of a particular weight can decrease performance. I.e. a spitfire VIII weighs about 182 lbs. extra over the Mk.IX at tare weight. Also the takeoff weight with full fuel is about 220 lbs more. Draining the wing fuel of the VIII will make it about 190 lbs. heavier.
With that much more weight, how much does that much weight decrease performance by?
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does burning off ammo even do anythign some say yes some say no :/
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Weight is a caculated factor in AH2. You have to remember tho on a 7000lb plane 200 pounds is only 3 percent of total weight. Even the best pilots wouldnt notice this by doing manuevers. Anyone who thinks weight isnt modeled needs to check the climb rates with full and 1/4 load. The increase in performance is proportional to weight decrease (to a point).
In other words it does help but the amount of weight decrease to see an improvement is far larger than many realize.
I will do tests to prove my point.
CFYA
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I used the BF 110-G2 since its the plane most often used with a single seat tail gun. I also see many people emptying the tail guns. Here are my test results.
Weight: A 97lb decrease.
W/ Ammo-16018lbs
W/O Ammo-15921lbs
Climb:29 fps increase
W/ Ammo-3282 fps
W/OAmmo-3311 fps
While it does make a diffrence its none youll ever notice in a plane of this type.
Ryan
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thats some cool stats:aok
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Thanks!
FYI All stat were recorded at 5k with auto climb from sealevel to provide time for the flight profile to normalize.
CFYA
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Originally posted by weazely
does burning off ammo even do anythign some say yes some say no :/
Yes it sure does.
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In most of the P-47's, the difference in the 275 rpg and 425 rpg ammo load for 8 guns is worth about 1.5" of manifold pressure difference in rate of climb. By that I mean, if a squad mate and I are in formation climbing, and he has the 425 rpg ammo load and I have the 275 rpg load (with the same fuel load), I have to back out of the throttle by 1.5" of MP to keep from overtaking him during an Alt-X climb. Its about a 400 lb.+ difference, which is a small percentage of overall weight, but noticeable enough in flight.
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109G2
100% Fuel
1000 7.9mm
200 20mm
With the 7.9mms
6858lbs.
Without the 7.9mm
6793lbs.
65lb difference
less then 1% of the wieght
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Spitfires have relatively small fuel tank. The weight difference between 50% and 100% is not dramatic. On the other extreme, you have the P47N. Load it up 100% and 50% and see the difference.
100% on the N is 550 gallons. that is the fuel load of 5.5 fully fueled Spit 16s.
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Although many dullards refuse to acknowledge that some of the finer fliers can feel the difference, we can. In duels where pilots are very, very close in pilot skill (the kind of duels BatfinkV and I have, where we never know who's going to win until the final shot lands), an extra two hundred pounds can make the difference between winning and losing equally, and losing all the time.
The difference between a Spitfire with a quarter tank and one with three quarters is about two hundred and fifty pounds. If you're close enough to your opponent that you both win equal numbers of duels, taking an extra half tank will make you lose consistently. Even just taking an extra quarter tank (a hundred and twenty five pounds) will do so. It's been tried and proven.
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The effect weight has on performance is always evident. However, much depends upon the aircraft.
For example, the weight fuel and ammo in some aircraft makes a substantial difference in performance. For most American fighters, the weight difference can vary between 7% to well over 9%. This is certainly significant.
Here's some examples of optional fuel and ammo loads for some American fighters:
P-38L:
Full internal fuel and max ammo: 17,700 lb
50% fuel and reduced ammo: 16,098 lb
P-47D-40:
Full internal fuel and max ammo: 14,951 lb
50% fuel, 6 guns, 267 rds/gun: 13,161 lb
P-47N:
Full internal fuel and max ammo: 16,692 lb
50% fuel, 6 guns, 267 rds/gun: 14,355 lb
P-51D:
Full internal fuel and max ammo: 10,089 lb
50% fuel, six gun installation: 9,368 lb
50% fuel, four gun installation: 9,213 lb
F4U-1A:
Full internal fuel and max ammo: 12,904 lb
50% fuel and max ammo (no ammo options): 11,821 lb
Here's some Luftwaffe fighters for comparison.
Bf 109G-14:
Full internal fuel and max ammo (30mm): 7,253 lb
50% fuel and max ammo (20 mm): 6,823 lb
Fw 190A-5:
Full internal fuel and max ammo (4 cannon): 8,780 lb
50% fuel and max ammo (2 cannon): 8,167 lb
Note that the difference between weight of fuel is far more significant in the American fighters than in the German aircraft. Obviously, this is due to the huge internal capacity of the American aircraft required for long range operations.
To ignore these differences is to suffer an unnecessary loss of performance.
This is why it is often far better to take reduced internal fuel and add external drop tanks to get you to the fight, where they can be pitched off for combat.
Likewise, one should look at the ammo load and decide if lower weight options would be beneficial for the particular circumstances expected.
For example, to run out gas long before you can expend your ammo means that you were carrying more ammo or less gas than needed. There is certainly some need for basic planning.
For pilots who fly their aircraft to its limits, extra weight is an unwanted burden.
A typical load-out for my P-38J for a base attack sortie would be 50% internal fuel, one drop tank and one 1,000 lb bomb. Ammo load is usually 200 rounds per MG and the standard 150 cannon rounds. About the time I've used most of my ammo, my fuel state is such that I need to return anyway. The bomb is carried in the event a target of opportunity is discovered (GVs, buffs spawning or the VH needs a little attention). For base defense against GV attack, I'd take 50% fuel and two 1,000 lb bombs (I never take rockets on any P-38 as the drag penalty is excessive).
I'm one of those guys who likes to look for the sneak attack by GVs or an NOE. I then select the aircraft I deem is best for the situation and beat off the attack as best as I can. A skilled pilot in a potent fighter can tear an NOE to shreds. Against the NOE I prefer the SpitVIII or La-7. Against the GV mob, I'll fly whatever will work best.
Just remember, excessive internal fuel cannot be jettisoned like drop tanks or ordnance. Therefore, avoid taking too much internal gas, adding external fuel if needed.
My regards,
Widewing
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There are two factors working in the weight equation relative to flight.
The first, as in performance automobiles, is HP to weight ratio. HP/weight ratio directly affects speed. The higher the HP is to the relative weight the better the performance. Since we can't increase HP in a given plane the only modification we can make to improve HP/weight is reducing weight. This is more noticable in planes with either low HP or big fuel tanks and less so in high HP/small tank rides.
The second factor is lift. Airflow over the wing must produce enough lift to overcome the weight of the aircraft (lift/weight ratio). As the weight of the aircraft increases the airflow must also increase (i.e. the airflow over the wing must be faster at a higher weight). The opposite also holds true. Wing size and design plays a role here and planes with large wings will show less effect than those with small wings.
So, you can see that this creates a compound effect. Reducing weight increases HP/weight giving you more speed. More speed = more lift against an already lighter aircraft further improving the already enhanced lift/weight ratio. The compound effect is quite noticable.
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Originally posted by Widewing
Against the NOE I prefer the SpitVIII or La-7. Against the GV mob, I'll fly whatever will work best.
Just remember, excessive internal fuel cannot be jettisoned like drop tanks or ordnance. Therefore, avoid taking too much internal gas, adding external fuel if needed.
My regards,
Widewing
Thanks all for the info!
But Widewing's quote above is what I've been wondering about. Why would one choose the spit8? extra fuel over the 9? Whenever I fly the spitfire LF VIII, it feels like a brick compared to the IX, even when I've burned off the wing tank fuel, and a bit of the main tanks' fuel loads (since VIII's have 96 IG in the 2x main tanks as opposed to the IX's 85). No matter what, the VIII feels really heavy.
So I looked some stuff up. Turns out that the tare weight report (no oil, fuel, ammo, radio, guns, gun cam) which I THINK includes hydraulic fluid states the VIII's tare is 5,931 lbs. and that the IX's is 5,749 lbs. That's not even 200 lbs. of difference. Being similar/practically the same aircraft, the loads carried (provided they are both fitted with the same amount of fuel) should show that their T/O weights as also being only 182 lbs. in difference (unless tare weight does NOT include the Mk.VIII's extra hydraulic fluid for the tailwheel). The reason why I think tare weights do not include these hydraulic fluid is because the charts showing the Spitfire XIV's weights and loadings on www.spitfireperformance.com (http://www.spitfireperformance.com) does not factor in the hydraulic fluid.
If I'm right, this would mean that the Spitfire VIII should handle almost identically to the Mk.IX, except for in the roll.
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The Spitfire Mark VIII is much faster than the Mark IX. is it not?
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Originally posted by Benny Moore
The Spitfire Mark VIII is much faster than the Mark IX. is it not?
It is.
In AH2, the Mk VIII handles almost identically to the Spit 16, not Spit 9.
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That is due to the engine.
The Mk IX has the high blown Merlin 61.
The Mk VIII has the low blown, more powerful Merlin 66.
The Mk XVI has the American built version of the Merlin 66, the Merlin 266.
Above 20,000ft the Mk IX has a marked advantage over the Mk VIII or Mk XVI. Below 15,000ft the reverse is true.
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Well i meant in handling qualities.
In terms of power and 'hanging' abilities, I realize that the Merlin 66-powered SpitVIII has 1720 hp as opposed to the Mk.IX's Merlin 61 of only 1585 hp.
Also, the speed qualities are not as bad as Karnak stated. The top speed of the LF VIII and XVI is 404 mph (409 approx for the clipped wing 16) at 21,000' while the Merlin 61 allowed for a speed of 408 mph at 25,000' I believe. I know though that the 'LF' Merlins did not impact performance that much. At sea-level, the differences are much more evident. Merlin 66's allowed for 335 mph in real life as opposed to the 315 mph of the Merlin 61. Climb rate was also vastly changed from the 61's max. of 3860 fpm at 12,600' to the 4,700 fpm at 7,000' and 3,860 fpm at 14,000'. At 20,000' the 61 has 2,930 fpm while the 66 has 3,560 fpm. It's not until 24,000' that the 61 has the advantage due to its supercharger 2nd stage kicking in, and only slightly.
But yes, correct me if I'm wrong on my 'tare weight' theory. (Also, I found a document from a book that the Spitfire IX had a rear ferry tank like the Malta Mk.Vc's had... however I can't find any evidence supporting that the IX did carry that small 29 Imp. galloner. I can only find evidence of the rear tanks of 75 IG. If anyone has smoe evidence, I'd like some thanks!)
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Top speed obtained after long acceleration periots are not the only issue. You will find the Merlin 61 puts out a lot more power above 20,000ft, so acceleration and climb are much better on the Mk IX than the VIII or XVI.
Of course the XIV is better yet.
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Blah. i feel that the 16 isn't really that Spitfire-ish. i really don't like flying that.