Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: DweebFire on December 09, 2007, 08:40:48 PM
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I've done some research on the Spitfire's weights recently, and reading up on SgtPappy's posts, I've come to the conclusion that the weights posted at Spitfire Performance (http://www.spitfireperformance.com) may have some errors. If this really is the case, how credible is the rest of the site?
Don't get me wrong it's a great, well-putogether site, but some data seems misleading.
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Originally posted by DweebFire
I've done some research on the Spitfire's weights recently, and reading up on SgtPappy's posts, I've come to the conclusion that the weights posted at Spitfire Performance (http://www.spitfireperformance.com) may have some errors. If this really is the case, how credible is the rest of the site?
Don't get me wrong it's a great, well-putogether site, but some data seems misleading.
What do you have access to that is more reliable than the data and tests presented on that website? I mean, that data is what Historians classify as Primary Source Documents.
Please tell me you're not using a commercial trade book for comparison.
My regards,
Widewing
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Will...not...make....smart... .aleck.....remark......will not....! :)
Oh but it's so tempting.....:t
And yeah I'm with Widewing on this one.
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Originally posted by Guppy35
Will...not...make....smart....aleck.....remark......will not....! :)
Give yourself to the Dark Side...
Darth Ack-Ack
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Kind of hard to reply when you don't really say anything specific. I certainly wont be naive enough to think there is no possibility of a few errors on any document (to err is human after all), but you have to at least make a case first.
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Originally posted by Ack-Ack
Give yourself to the Dark Side...
Darth Ack-Ack
Come to the Dark Side...... We have cookies:D
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Sorry I left it out all.
No, no, I'm not saying its a horrible site, I should rename the thread. Hah. I feel bad now. There's no other site that has been more credible to me actually.
Anywho, we got one small example. Likely would not counter the credibility of the rest of the site, but there's often experimental error in many tests.
One of the tests I found was the Corsair tests I've seen stated before in these forums. For one thing, there are the F4U tests sheets stated on the bottom of F4U Performance Summary (http://www.wwiiaircraftperformance.org/f4u/f4u.html) has some weird results. The British 100 octane was the same as 100/125 US grade right? The tests have some weird figures., rarely going over 400 mph on the FAA tests.
Other random figures includes the Spitfire weights. Like Pappy once stated, the weights are iffy. He just wants me to restate it while I'm here since we're using the same comp.
Spitfire VIII: full ammo, full fuel (123 Imp. Gal): 7807 lbs. / 25% fuel, full ammo: 7137 lbs. / no fuel, no ammo: 6678 lbs
Spitfire IX: full ammo, full fuel (85 Imp. gal): 7303 lbs. (7445 lbs. on the site) / 25% fuel, full ammo: 6843 lbs. (6986 lbs from calculations based on site) / no ammo, no fuel: 6455 lbs. (6590 lbs. from calcs)
The tare weights for both planes are 5931 lbs. (VIII) and 5749 lbs. (IX). The VIII has everything the IX has but more.. i.e. more hydraulic fluid, more fuel, etc. Nothing that I know of is subtracted. Their tare weights differ in 182 lbs. When you get their weights based on the website and subtract fuel and ammo weights (based on the site as well) you find that their weights only differ in 88 lbs.
So I'm assuming that there's a problem with something.. and I'm finding a problem with what I should trust on the site and what I shouldn't. A weight diff. in 88 lbs. vs the in-game 223 lbs is a little weird. maneuverability change is a big difference with such weights.
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Originally posted by DweebFire
One of the tests I found was the Corsair tests I've seen stated before in these forums. For one thing, there are the F4U tests sheets stated on the bottom of F4U Performance Summary (http://www.wwiiaircraftperformance.org/f4u/f4u.html) has some weird results. The British 100 octane was the same as 100/125 US grade right? The tests have some weird figures., rarely going over 400 mph on the FAA tests.
Specifically, which test are your referring to? URL is? There are many reports jammed into the summary page.
My regards,
Widewing
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Go through Spitfire the History. There are all kinds of different 'test' Spits listed and finding two from the same mark that aren't off in weights by a bit is hard.
Did the VIII in the tests have a broad chord rudder or the early rudder? Did it have the pointed tips, normal span wings or clipped?
Was it an early IX without the tropical filter? Did it have a Universal wing or E wing? Did it have the pointed rudder or rounded one? Did it have clipped, normal or pointed long span wings?
It goes on and on.
In the end a Spitfire VIII totally empty with tropical filter, broad chord rudder and normal span wings vs a Spitfire IX with a tropical filter, broad chord rudder and normal span wings is going to be the difference of the retractable tail wheel and the two inner wing fuel tanks.
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Guppy,
Thanks for clearing that up. The VIII used in the tests were the old rudder, the normal filter (like the ones on Mk.V spits) and Mk.VII wing tips.
The IX was Merlin 61 engine, regular rudder, likely a Mk.V filter as well since the test was during 1942.
That however is almost exactly the same as our Mk.IX in game and our weights are still off by some 140 + lbs.
Widewing,
I'm not sure about my figures,but it's widely published that the F4U-1 series Corsairs have speeds of at least 417 mph on 100/130 octane.
The tests here (http://www.wwiiaircraftperformance.org/f4u/corsair-II-III-ads-a.jpg) yield much different results. I know this has been shown this before.
Lastly, I have come to the conclusion that the Bf 109K's ang G's late in the war (fitted with Nitrous Oxide boost) could produce in excess of 2000 hp. Our figures don't seem to show that. I could be wrong, but the boost is supposed to raise performance levels by a higher percentage than planes with standard or water-injected WEP... but it all seems like regular WEP on Gonzo's charts.
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I'm not 100% sure about the K4, but in general AH's 109s dont have NO boost, just regular water/methanol.
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Originally posted by DweebFire
Lastly, I have come to the conclusion that the Bf 109K's ang G's late in the war (fitted with Nitrous Oxide boost) could produce in excess of 2000 hp. Our figures don't seem to show that. I could be wrong, but the boost is supposed to raise performance levels by a higher percentage than planes with standard or water-injected WEP... but it all seems like regular WEP on Gonzo's charts.
G-14 and K-4 in game both have MW-50 (water methanol injection) and perform very well. G-14 is a little slow at altitude, maybe 10mph, but so are a few otherr planes we have (F6F comes to mind). As for GM-1 (nitrous oxide), 109s were being fitted with MW-50 instead by 1944 due to less weight of the system and the introduction of the DB 605AS and DB 605D engines. These engines gave good performance at altitude without having to resort to nitrous oxide.
Nitrous oxide could only be used above the rated altitude of the engine. I believe 1000m above rated alt for first stage of GM-1 boost, but I'd have to check on that. In a Bf 109g-6 for instance you could not engage GM-1 until around 26000-27000ft or so.
As for spitfireperformance.com., all the actual tests and their data are taken from period documents, and many times scans of the original documentation are included. In cases where the scans are not included I believe that Mike Williams has listed the references. I don't know how much more credible you can get than that. Interpreting the data is a different story since different weights and configurations can have significant effects on performance as has been stated already.
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Weight comparisons between the VIII and IX will also differ based on wing armament and wing tips, tail type, ect. Radio model installed? different tires?
The 100 pound discrpancy could be any # of things. Its a very small ammount after all, 1.2 percent? of the 7300 lb weight.
It could be anything.
Also, in AH, you cannot get a weight the weight of an a/c with no oil and hydraulic fuel, only avgas and ammo. There could be a flaw in that calculation as well.
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Originally posted by DweebFire
Widewing,
I'm not sure about my figures,but it's widely published that the F4U-1 series Corsairs have speeds of at least 417 mph on 100/130 octane.
The tests here (http://www.wwiiaircraftperformance.org/f4u/corsair-II-III-ads-a.jpg) yield much different results. I know this has been shown this before.
There's no doubt that there are some rather odd test results found in some war-time test results. But, that doesn't reflect on the website, because Mike and Neil provide a chart showing these differences..
(http://www.wwiiaircraftperformance.org/f4u/f4u-level.jpg)
My regards,
Widewing
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Another point is that the different aircraft are not always submitted to FAA tests in completely 'new' condition. Gages may also have been faulty or misread, as it was not uncommon. If you take a look at the last test on the Corsair IV, you'll notice its speed as 415 mph. About 10 away from the recorded F4U-1D speed of 425 mph. This may be due to rocket/bomb tabs/hardpoints or other drag causers. no plane was the same.. not even 2 Corsairs built side by side.
In Australia Spitfires were delivered with lots of faulty equipment.
Squire, I think Dweeb stated before about the Spits' configs. Though I'd like to add to his statement that the Mk. VIII and IX both had TR.1133 VHF radio sets at the time. Also, both had identical C-type wings... one difference was that the Mk.VIII had shorter ailerons... not sure if that factors in any weight differences.
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Originally posted by DweebFire
Guppy,
Thanks for clearing that up. The VIII used in the tests were the old rudder, the normal filter (like the ones on Mk.V spits) and Mk.VII wing tips.
The IX was Merlin 61 engine, regular rudder, likely a Mk.V filter as well since the test was during 1942.
That however is almost exactly the same as our Mk.IX in game and our weights are still off by some 140 + lbs.
So you are talking an early Spit IX which is in essence a Spitfire Vc with the Merlin 61, rounded rudder, normal span wings and no tropicalization.
The Spit VIII would have the beefed up fuselage, tropical filter, extended wing tips, retractable tail wheel and wing tanks. VIII's were meant for overseas service and were tropicalized from the start.
That in itself would probably amount to the weight difference.
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True, yet the Spitfire IX in the tests are practically identical to the in-game Spitfire IX, the only difference being our IX has an Aero-Vee air filter and the one in the test likely did not.. it was a 1942 test, and that plane had an all-up weight of 7445 lbs, no DT's, no ord, just full ammo, B-type armament in a C-type wing; just like our IX.
The VIII with long span wings and (likely an Aboukir filter that I've seen on really early Mk.VIII's) and a normal chord rudder is the test plane. Our in-game one is the typical Spit VIII of late '43 - both planes are consistent in weights.. in the tests, the latter Spit VIII is 7800 lbs and the in-game VIII is 7807. Nothing seemingly wrong there. If anything the removal of long span should make the plane lighter. The wide chord rudder, I think, wouldn't add much weight.
And our weights still come up strange when using those calculations and plugging in these factors: weights and loadings (http://www.spitfireperformance.com/ab197.html)
I'm not doubting that the Mk.VIII is heavier than the IX. The problem lies in the fact that the Mk.IX is too light and should reflect more upon the VIII's weight.
But when the calculations ARE completed from the test information, the weights seem weird since the Mk.VIII SHOULD weigh at LEAST 182 lbs. vs. the IX at all configurations, but using official all-up weights and subtracting fuel/ammo, we find the VIII is only 88 lbs. heavier.
So the game SEEMS to have correct weight differences between the VIII and IX but incorrect weights for the IX according to tests.
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Originally posted by Guppy35
So you are talking an early Spit IX which is in essence a Spitfire Vc with the Merlin 61, rounded rudder, normal span wings and no tropicalization.
The Spit VIII would have the beefed up fuselage, tropical filter, extended wing tips, retractable tail wheel and wing tanks. VIII's were meant for overseas service and were tropicalized from the start.
That in itself would probably amount to the weight difference.
By this, do you mean they were bathed in Alodine from birth to account for the increase in gross weight?
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Originally posted by Wolfala
By this, do you mean they were bathed in Alodine from birth to account for the increase in gross weight?
I don't think Alodine is dense enough. It must be a healthy coat of Zinc Chromate on everything...
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Merlin 61 Spitfire F.IX from the docs provided:
".2.4. Loading. The tests were made at a take-off weight 7805 lbs. with the bomb on"
Quoting the 1942 F. IX Merlin 61 takeoff weight, fuelled, and armed.
...Less the 500 lb bomb, you get 7303 lbs. Exactly the loaded weight of the F. IX Merlin 61 in Aces High, to the pound (with no bomb).
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You're right but this is weird... why are the weights different from those in the weights and loading test...? Maybe the prop... on most tests, they say Hamilton Standard Hydrodynamic propellor or something like that... on this test, they just say 'four bladed propeller, Type R3/4F5/3'. Anyone know what that is?
Additionally it says that the 303 guns and accessories are removed and 'No W/T aerial I.F.F. aerials' Is this (http://www.spitfireperformance.com/bs428.html) the test youre referring to?
I don't believe these weights make sense because the all-up weight ended as 7445 lbs. not 7805 or 7303 lbs. in the documents i provided in my previous post.
In this (http://www.spitfireperformance.com/spit8tac.html) test, the long-span, Merlin 63 Mk.VIII has a weight of 7,760 lbs. even less than the game. I think an increase in wing span with a normal rudder would be heavier than a normal span with a 'Griffon' rudder.
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There is a difference of more than a hundred pounds with some of the props (wood vs metal), as well the Spitfire IXs in many of those tests were carrying 95 Imp gallons, as opposed to the 85 gallons (102 US) the Aces High Spit IX has, thats another 78 pounds right there.
Some had two 48 gal Imp tanks (95) some had a 37 gal and a 48 gal (85).
Also, some Spit IXs had rear fuselage tanks, and again, thats going to mess with weights.
With a diff prop and a 37+48 tank, the weight diff could be as much as 188 pounds.
Seems there are many quoted weights for the F. IX, but I think 7303 loaded with no bomb carrier is close to the mark, with just fwrd fuel carried. There are other tests where they are fully equipped with loaded weights @7300-7400. You need an exhaustive list of the exact components to make a comparison, and thats hard to come by.
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Maybe the test Pilot had a heavy meal? :rofl :rofl
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The following link, I think, has enough of that info needed. Here (http://www.spitfireperformance.com/ab197.html)
No Merlin 61 Spitfire IX carried the extra fuel in the rear tanks operationally in 1942. The test states the fuel load to be the standard 85 Imp. Gallons.
Also, the propeller type is stated in every test. If it isn't, the Spitfire is carrying the most common prop type. It's always somewhere there in the test description or on a list. The above test states that it was a Rotol Duraluminium (Dural) propeller.
If I'm not mistaken, the British definition of 'gross weight' is the weight with all accessories, full fuel, full ammo but no external tanks/ords. In addition, the planes are always armed with 2x 20mm cannon (120 rpg) and 4x.303" MGs (350 rpg) unless stated otherwise.
The weight still stands as 7445 lbs.
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The prop type might be stated in every test, but the Spitfire IXs eventually went with the Rotol Hydulignum props (laminated wood) that are not from the test above.
Aces High does not have to model "AB917" from October 1942 (a converted MkV version, and one of the earliest in the production run) with a Rotol metal prop to have a Merlin 61 F.IXc
Weights in one specific model are not absolutes, unless the installed equipment never varied, and there is almost no combat a/c that thats true for.
I dont have HTCs data, and I cant say what model of the F.IXc they went with, unless they want to post it. They have never stated, to my knowledge what precise version they modelled.
Im not saying the couldn't model AB917, im just saying they didnt have to.
Personally, I would have liked to see a Merlin 63 F. IX, rather than the Merlin 61.
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True, weights are never the same or rarely the same for 2 aircraft, even if of the same variant. All of the tests except the bomb test have the Spit's weight at or above 7400 lbs.
I too would rather have the Merlin 63 version... though we get more of the taste of time when they give us the Merlin 61 version.