Originally Posted by winny (Post 457539)

A quote from "Spitfire in combat" Dr. A. Price

'In Spring 1940, in a bid to further improve fighter performance, the RAF introduced 100 octane petrol in place of the 87 octane fuel previously used. In the case of the Merlin II and III engines fitted to Spitfires, this gave no improvement in performance at or above the engnes' full-throttle altitude of 16,500. Below that altitude however the new fuel gave a valuable increase in power. Supercharger boost could be increased from +6.5 lb to 12lb. That increased the Spitfires maximum speed by 25mph at sea level and 34 mph at 10,000 feet....

(he then goes through a list of modificatons that cost the Spitfire speed)

.....The maximum speed usually quoted for a Mk I is 362 mph @:18,500. But that figure reffered to K9787, the first production aircraft during it's initial performance tests in 1938 at an AUW of 5,819lb. By the summer of 1940 the maximum speed of a fully equipped Mark I was somewhat lower, about 350 mph at the same altitude'.

My personal opinion is that the in-game Mk I should be hitting around 350/360 mph depending on loadout @18,500 feet. It's also a shame that the same sort of info doesn't seem to exist for other types in the game.


EDIT: List of some of the modifications between K9787 and a BoB era Spit I that cost speed

73 lb's worth of pilot's armour
Bulletproof windscreen (cost around 6mph aerodynamically)
3mm armour plating for the upper fuel tank
IFF Aerials (cost another 2-3mph aerodynaically)

Total weight of above mods 335 lb.

Originally Posted by Redroach (Post 457444)

with which weapon configuration(s) and with which ammo load(s) did the RL-tests take place?

Originally Posted by camber (Post 457467)

Perhaps I am not understanding the question fully,

Originally Posted by camber (Post 457467)

but all Spit Ia's at +6.25psi boost (full throttle) should go the same speed whether they are using 87 or 100 octane.

Originally Posted by camber (Post 457467)

The Spit 1a 100 octane has the ability to use +12psi (using the modified boost cutout red tab)

Originally Posted by camber (Post 457467)

and go faster (provided it is below FTH for +12psi). There is an intermediate altitude range where the supercharger can give less than +12psi but more than +6 psi, above that 87 and 100 octane variants are equal.

Originally Posted by ACE-OF-ACES (Post 456989)

but isn't the real world +6 lbs. Spitfire using 87 octane? If so, shouldn't the in-game 100 octane (i.e. +12 lbs.) version be faster that the +6 lbs. below the FTH?

Originally Posted by camber (Post 457467)

I assume your flight tests for the CoD Spit 1a 100 octane were using the +12psi boost?

Originally Posted by camber (Post 457467)

Did the engine blow up during tests?

Originally Posted by winny (Post 457471)

The RL data for a mk I (if it's the data usually quoted, top speed 363mph) was taken from a Spitfire that was at least 300 lb lighter than a mkI in Battle of Britain trim. It was around 5,800 lb as opposed to 6,100 lb (ish). It was the eight gun version, didn't have the pilot armour, bullet proof windscreen ( reckoned to cost 3-4 mph) or the IFF aerial (again another 2-3 mph). The only reference I've seen to it is by Dr Alfred Price. He says in "Spitfire in combat" that the top speed was closer to 350 mph for a BoB era MkI. It's a bit vague, I know, but does highlight how difficult it is to get accuracy. He knows his Spits though..

Originally Posted by NZtyphoon (Post 457596)

The constant-speed propeller on N3171 made a big difference in take-off distances (225 vs 320 yards, 370 vs 490 to clear 50 ft screen) and rate of climb. N3171 was fitted with the windscreen, 3mm alloy sheet (not armour) over the fuel tank and domed canopy. Once fitted with armour and IFF the rate of climb would have gone down as would the top speed.

That aside the real problems still lie in CLOD performance below 10,000 ft using +12 lbs boost, which has not been modelled properly:

http://i91.photobucket.com/albums/k3...reMkI12lbs.jpg
© ACE-OF-ACES INC. 2012

Originally Posted by winny (Post 457611)

Never seen a 93 page thread on a hurricane or 109.

Originally Posted by winny (Post 457471)

The RL data for a mk I (if it's the data usually quoted, top speed 363mph) was taken from a Spitfire that was at least 300 lb lighter than a mkI in Battle of Britain trim. It was around 5,800 lb as opposed to 6,100 lb (ish). It was the eight gun version, didn't have the pilot armour, bullet proof windscreen ( reckoned to cost 3-4 mph) or the IFF aerial (again another 2-3 mph). The only reference I've seen to it is by Dr Alfred Price. He says in "Spitfire in combat" that the top speed was closer to 350 mph for a BoB era MkI. It's a bit vague, I know, but does highlight how difficult it is to get accuracy. He knows his Spits though..

Originally Posted by Redroach (Post 458160)

(that website I was directed to looks really nice)!

Originally Posted by Crumpp (Post 458465)

It does not do any good to model an aircrafts speed, climb, and turn performance but not reproduce it's flying qualities.

You are not "simulating" anything.