DCS Spitfire Mk IX performance

[rel4y]

A correction on my part: Morgan and Shacklady, page 282, shows there were three types of Vokes filter systems: Type A, without a louvred plate under the filter element; Type B w/louvred plate (mod. 1068 ) and Type C with an extra plate with square holes on top of the filter element, plus modifications to the seals. There was no change in the filter element itself. What did change was the louvered plate reduced the performance loss from having the filter element open directly into the intake, as shown in Yo-Yo's attachment.

 

Interesting! It really is a clever and practical design by the brits and much better than the Mk V one. So type A would resemble the dotted line in the graph (forums.eagle.ru/attachment.php?attachmentid=137453&d=1459196786) and type B the dash dot line. As for type C, I dont really see any benefits to the design. Do you have any info when these were introduced?

Edited March 30, 2016 by rel4y

[Nerd1000]

Interesting! It really is a clever and practical design by the brits and much better than the Mk V one. So type A would resemble the dotted line in the graph (forums.eagle.ru/attachment.php?attachmentid=137453&d=1459196786) and type B the dash dot line. As for type C, I dont really see any benefits to the design. Do you have any info when these were introduced?

For comparison, some info on the Mk V's vokes filter can be found here.

That site also has some other interesting stuff about operating the Spitfire Mk V in Northern Australia's rather demanding environment.

[Pilum]

Here is a chart showing the effects of weight on the Spitfire Mk9 speed as a function of altitude. As Yo-Yo already pointed out, weight does of course factor in at higher altitudes since the induced drag becomes more and more important at higher altitudes and weight is of course not unimportant and it is a big factor in determining the aircraft's ceiling and acceleration but that is another matter entirely. However, as can be seen in the figure, for the Spitfire Mk9 with its relatively low wing loading the effects of a 5% difference in weight on maximum speed up to and including FTH are negligible.

 

Finally, as Otto pointed out earlier, there is no easy way for you to verify the accuracy of my simulations since you only see results. However, I have posted in various sim forums over the years and I think you can verify the accuracy of the C++ model in the same way you would verify a flight simulator: Compare the sim data with IRL data and see to what extent they agree. IMHO I think what I have posted so far over the years tabs pretty well with IRL median values but then again I can’t be considered impartial can I so you just need to form your own opinion. :smilewink:

[Rogue Trooper]

I am really looking forward to this tight powerfull warbird.

I truly prey to the gods that we get the full and clipped wing versions... Christ I prey!

Edited April 1, 2016 by Rogue Trooper

[Friedrich-4B]

TThat's one part of it of course, and this experimental design was anything like the SU carbs used later on cars, it had several disadvantages such as inaccurate fuel metering during cruise conditions and more sluggish throttle response.

 

The S.U Injection system was, in fact, standardized for several later Merlin models (e.g - Merlin 130 series in De H Hornet). It had nothing in common with the S.U. carburettors used in cars (which (warning OT), BTW, work extremely well when properly maintained - problems such as "inaccurate fuel metering and sluggish throttle response" are the result of inadequate/careless maintenance and are not inherent to the design http://britishclassicmotors.com/3301.html ).

 

In fact you do not have to look further than the results of BS 354 to get just how odd the BS 543 test run yielded when it came to FTH and altitude results, quite similar to the DCS Spitfire IXPerimental FM model which also yields a 2000 feet increase in the FTH, even in a 170 mph climb...

 

It is slightly sad that someone who has long been a deeply devoted Spitfire fan, is so disappointed with how the DCS L.F Mk. IX is likely to perform, especially because he has gone to such lengths to provide Yo-Yo with a comprehensive, in depth analysis proving that the Spitfire should lose at least 3 mph.

 

Interesting! It really is a clever and practical design by the brits and much better than the Mk V one. So type A would resemble the dotted line in the graph (forums.eagle.ru/attachment.php?attachmentid=137453&d=1459196786) and type B the dash dot line. As for type C, I dont really see any benefits to the design. Do you have any info when these were introduced?

 

It would seem that the Type A design was first used in the Spitfire VIII as Mod 751, October 1942; Type B was first tested on MA648 in November 1943 (hence "new" intake design) [from Morgan and Shacklady, pages 289 & 316].

 

Type C had improved seals, as well as the additional plate, possibly as a result of the test cited by Yo-Yo.

[Friedrich-4B]

For interest, in March 1944, MJ823 was tested by the A&AEE with 2 x 250 lb bombs on underwing racks, while in June it was tested w/1 x 500 lb bomb under the fuselage and 2 x 250 lb underwing bombs. Is ED's FM likely to carry these loads as options?

[MiloMorai]

Spitfire expert says:

 

The Mk V. with C wings could indeed carry 4 Hispanos (it was rare though, IIRC there was a lack of Hispano supply), even though 2x20+4x7.7mm was more common. Indeed you are right that the Mk IX was basically a reworked Mk V structure, however you forget that the Mk IX was much heavier, and the tires/undercarriage could not support the extra weight of the Merlin 60 series AND the extra Hispanos. I have never ever seen evidence of any operational Mk IX ever carry 4 cannons. In fact it seems that the wing structure and u/c could not support that until the redesign occuring w. the Mk 2x series.

 

The redesign must have occurred before the Mk2x series as 1000lb of bombs weigh substantially more than 2 extra 20mm H-S cannon and ammo.

 

So, how expert is this Spitfire expert?

[71st_AH Rob]

Spitfire expert says:

 

The Mk V. with C wings could indeed carry 4 Hispanos (it was rare though, IIRC there was a lack of Hispano supply), even though 2x20+4x7.7mm was more common. Indeed you are right that the Mk IX was basically a reworked Mk V structure, however you forget that the Mk IX was much heavier, and the tires/undercarriage could not support the extra weight of the Merlin 60 series AND the extra Hispanos. I have never ever seen evidence of any operational Mk IX ever carry 4 cannons. In fact it seems that the wing structure and u/c could not support that until the redesign occuring w. the Mk 2x series.

 

The redesign must have occurred before the Mk2x series as 1000lb of bombs weigh substantially more than 2 extra 20mm H-S cannon and ammo.

 

So, how expert is this Spitfire expert?

 

Milo, the redesign you're thinking of I think is the MkIXe. The c wing could carry 4 x .303 and 2 x 20 mm or 8 x .303 or 4 x 20mm and at some point, A/C assigned to 2 TAF were modified to carry 2 x 250 lbs bombs. Early c wing MkV may have suffered from a shortage of Hispanos as Spitfire Expert speculated but I also seem to remember that the feed was redesigned again at some point in the MkV production.

 

The e wing could carry 2 x 20 mm and 2 x .50 and 2 x 1000 lbs bombs or 4 x 20 mm. Early e wings had cannon blisters like the MkVc but again the feed mechanism was changed back to a belt and box allowing the cannon to be mounted closer together. This wing I understand was capable of carrying the load but I have heard that the stress of firing the four cannon and carrying the bombs which were positioned directly below the cannon causes stress on the wing and since the primary purpose of the 2TAF MkIXe was CAS the use of the .50 made practical sense anyway so not sure if the structural argument isn't just pure conjecture.

I would love to have this as a wing option. The .303 will be next to useless against contemporary opponents, never mind the K-4, the.50 will give ussufficient hitting power to do damage and sufficient ammunition to stay in the fight, the 20mm will give us decisive hitting power but with only 120 rds per gun.

[flare2000x]

Milo, the redesign you're thinking of I think is the MkIXe. The c wing could carry 4 x .303 and 2 x 20 mm or 8 x .303 or 4 x 20mm and at some point, A/C assigned to 2 TAF were modified to carry 2 x 250 lbs bombs. Early c wing MkV may have suffered from a shortage of Hispanos as Spitfire Expert speculated but I also seem to remember that the feed was redesigned again at some point in the MkV production.

 

The e wing could carry 2 x 20 mm and 2 x .50 and 2 x 1000 lbs bombs or 4 x 20 mm. Early e wings had cannon blisters like the MkVc but again the feed mechanism was changed back to a belt and box allowing the cannon to be mounted closer together. This wing I understand was capable of carrying the load but I have heard that the stress of firing the four cannon and carrying the bombs which were positioned directly below the cannon causes stress on the wing and since the primary purpose of the 2TAF MkIXe was CAS the use of the .50 made practical sense anyway so not sure if the structural argument isn't just pure conjecture.

I would love to have this as a wing option. The .303 will be next to useless against contemporary opponents, never mind the K-4, the.50 will give ussufficient hitting power to do damage and sufficient ammunition to stay in the fight, the 20mm will give us decisive hitting power but with only 120 rds per gun.

 

120 rounds should be enough for most combat. I don't think I've heard anything from spitfire pilots books about 120 being not enough. It should be about 10 seconds of fire. Add the additional 5-7 seconds of .303 fire, which is great for popping coolant leaks and starting fires, and the Spitfire's armament should be more than enough. I don't see why you call the .303s "next to useless".

[Solty]

MkIXc had 240 20mm Hispano rounds. 120 per gun.

[flare2000x]

MkIXc had 240 20mm Hispano rounds. 120 per gun.

 

Sorry if I wasn't clear, that's what I meant. 120 per gun.

[Friedrich-4B]

Spitfire expert says:

Indeed you are right that the Mk IX was basically a reworked Mk V structure, however you forget that the Mk IX was much heavier, and the tires/undercarriage could not support the extra weight of the Merlin 60 series AND the extra Hispanos. I have never ever seen evidence of any operational Mk IX ever carry 4 cannons. In fact it seems that the wing structure and u/c could not support that until the redesign occuring w. the Mk 2x series.

 

So, how expert is this Spitfire expert?

 

Where on earth did that nonsense come from?? Spitfire IXs routinely carried 250 lb bombs, plus racks, under the wings on operations, with no reports from 2 TAF or any other source complaining of constant undercarriage failures. How, then, could the weight of another Hispano in the wing cripple the aircraft, when ~270 odd pounds + drag under the wing didn't? :huh:

[Krupi]

This does feel like a handicapped Spitfire :(

 

No 25 Pound Boost... Which I begrudgingly understand.

 

The type c not e wing feels like we are getting a 1943 Spitfire rather than a 1944...

 

I am a bit annoyed by these choices.

[MiloMorai]

Some more from the 'Spitfire expert':

 

Ok, so 7450 lbs is the MAXIMUM allowed landing weight of the spitfire IX and XVI. Adding the 2nd pair Hispanos would overload the airframe above the maximum allowed landing weight for the landings. Period, end of story.

 

:helpsmilie:

[JokerMan]

Some more from the 'Spitfire expert':

 

Ok, so 7450 lbs is the MAXIMUM allowed landing weight of the spitfire IX and XVI. Adding the 2nd pair Hispanos would overload the airframe above the maximum allowed landing weight for the landings. Period, end of story.

 

:helpsmilie:

 

Fuel

[9.JG27 DavidRed]

i really hope this spit will be a dangerous oponent for the 109 and 190.

[Talisman_VR]

i really hope this spit will be a dangerous oponent for the 109 and 190.

 

I don't think it will. We will have to wait for the Mk XIV for that.

 

In the combat flight sim world most hard core simmers are wised up about their aircraft due to a passionate interest and have hundreds, even thousands, of hours of stick time. It is impossible to simulate a near real life (weather and physical, etc,) and wartime situation, even though we try our best. In real life much more was going on rather than just the set up air-to-air duels that we take part in again and again on MP at the moment (hope that will change eventually).

The Mk IX is from a league below the Dora and 109K in terms of the technological development time line. I think it will be like racing with the previous seasons car in F1; you might put on a respectable performance now and then if luck goes your way (and get some PR for your sponsors), but don't expect to win the championship. Might be fun though.

 

Happy landings,

 

Talisman

[NineLine]

This does feel like a handicapped Spitfire :(

 

No 25 Pound Boost... Which I begrudgingly understand.

 

The type c not e wing feels like we are getting a 1943 Spitfire rather than a 1944...

 

I am a bit annoyed by these choices.

 

Doesnt feel handicapped to me so far...

[BIGNEWY]

Doesnt feel handicapped to me so far...

 

I concur :)

[Krupi]

That is encouraging to hear :D

[NeilWillis]

This does feel like a handicapped Spitfire :(

 

No 25 Pound Boost... Which I begrudgingly understand.

 

The type c not e wing feels like we are getting a 1943 Spitfire rather than a 1944...

 

I am a bit annoyed by these choices.

 

Well, it'd hardly be fair to go against any opposition on an equal footing if you're in a flying legend. Unless the 109 and 190 have an unfair advantage, the Spitfire wouldn't show just how legendary it is.

 

:music_whistling:

[9.JG27 DavidRed]

I don't think it will. We will have to wait for the Mk XIV for that.

 

In the combat flight sim world most hard core simmers are wised up about their aircraft due to a passionate interest and have hundreds, even thousands, of hours of stick time. It is impossible to simulate a near real life (weather and physical, etc,) and wartime situation, even though we try our best. In real life much more was going on rather than just the set up air-to-air duels that we take part in again and again on MP at the moment (hope that will change eventually).

The Mk IX is from a league below the Dora and 109K in terms of the technological development time line. I think it will be like racing with the previous seasons car in F1; you might put on a respectable performance now and then if luck goes your way (and get some PR for your sponsors), but don't expect to win the championship. Might be fun though.

 

Happy landings,

 

Talisman

 

i hope you are wrong.

[rel4y]

I know the discussion part of this topic has aged some time by now, but in the meantime I have discovered a few interesting facts about the tests discussed.

 

I) The long carburettor intake fitted with the "universal" Vokes Aero-Vee filter was first introduced 29-12-43 and became more or less standard in 1944. (also includes retrofit) The filter was later in 44 fitted with the louvred plate. The level speed tests conducted by RAE with the louvred plate fitted (and blanked off) took place in October 44. The conclusions were as followed:

 

Loss of effective ram with the filter elements fitted causes a vitrually constant loss of boost pressure at heights above the full throttle heights, rather greater in F.S. gear than in M.S. gear due to the higher supercharger compression ratio. The resulting loss in performance corresponds closely to the power loss caused by the decrease in boost pressure. At the higher altitudes the proportionate loss in boost, and therefore in performance, is increased.

 

Since these tests show no significant performance loss below the full throttle heights, and therefore no increase in drag due to leakage through the cleaner, it appears likely that the loss of ram is caused mainly by spoilage of the smooth flow of air through the intake by the irregular contour of the cleaner elements. This effect is largely eleminated when the louvred plate is fitted beneath the cleaner elements.

 

The effect of the cleaner elements in climbing performance is practically negligible.

 

When the air cleaner can be dispensed with, all performance losses due to the air cleaner can be avoided by fitting a plain blanking plate between the air duct and the filter elements.

The discussed graph can be found here:

https://forums.eagle.ru/attachment.php?attachmentid=137453&d=1459196786

 

II) The SU injection carburettor was never fitted to any Mk. IX/ Merlin 66 engines besides some preliminary tests. Below is a list of which Merlin engine used which carburettor type. The SU injection carb increased FTH by ~1300 ft and gave and increased max level speed by ~5 mph.

 

Merlin 61, 72, 73 used SU float carburettor

Merlin 66, 67, 70, 71, 76, 77, 85 used Bendix injector carburettor

Merlin 100, 104, 113, 114, 130, 131 used SU Injection carburettor

 

This is only relevant concerning the MA.648 test. (http://www.spitfireperformance.com/ma648.html)

 

The discussed graph can be found here:

https://forums.eagle.ru/attachment.php?attachmentid=137094&d=1458838872

 

Over and out

[Solty]

i hope you are wrong.

Or you could just check the data avaiable for the Bf109K and Spitfire LF MkIX 18lbs. Although, you should actually know how the fight looks from other simulations.

 

I agree with Talisman, people may be hyped, and I am glad we are getting a new airplane for DCS, but the Spitfire will not be an airplane that tips the balance. Though, it will certainly bring a breath of fresh air. For those that like to pull on the stick untill they see enemy tail, it will be the perfect choice :P

[9.JG27 DavidRed]

Or you could just check the data avaiable for the Bf109K and Spitfire LF MkIX 18lbs. Although, you should actually know how the fight looks from other simulations.

 

did i ask a question?did i ask for charts?did i ask how the Mk9 is modeled in other "simulations"?