any thing on the acceleration of the Spitfire

[thedab]

Hi I'm trying to find anything on the acceleration of the Spitfire, as the forum which I'm on a lot,

everybody tends think that the Spitfire has poor acceleration, but I was looking at the mk5 it has a very

good power to weight (yes I know it should be thrust to weight but this is all I know) and looks

to be better than the Yak-3,which everybody say has a excellent acceleration. so now I'm looking

for anything on the acceleration of the Spitfire ( and yes I have looked on Aircraft performance, but came up dry )

so if anyone know anything on the subject, can you help, as I want to know more on the subject

many thanks Ian

 

[Njaco]

I can suggest that if you search "Spitfire" on the forum and check through the threads that get selected, you may find an answer. I know, after reading through tons of threads on aircraft specs here, what you are looking for is posted. Maybe just not easily accessible.

 

[mhuxt]

Does the Spitty climb better than the Yak?

The reason I ask is, as my admittedly basic understanding goes, that the better-climbing aircraft will also be the better accelerating, as both are a function of excess power.

 

[thedab]

what I got for the Yak is 4.5 min to 4000m (which is about 16400ft)

what I got for mk5 on 16lb boost is 4.6 min to 16000ft which is close

is that a good ruler of thumb?

 

[tyrodtom]

4000 meters is about 13,000 feet, not 16,400 feet.

 

[Juha]

According to Soviet tests Spit F. IX (probably meaning LF. IX) accelerated better than Bf 109G-2/R6 bur worse than 109G-2 without the gun gondolas or Fw 190A-4

 

[thedab]

Well the mkIXF is with the 61(1585hp) or 63 Merlin (1710hp) and the LF would have the 66 Merlin (1720hp) so could be a mkIXF with the 63

With the G-2,them gondolas do weigh 215Kg,so that would hurt the G-2 performance. I take it that the G-2 was running on 1.42 ata?

 

[thedab]

sorry my bad,I must of type in 5000 in the converter calaulator

 

[Juha]

... I take it that the G-2 was running on 1.42 ata?

Not sure, the table gives the max speeds at 5000m 618km/h for Spitfire F. Mk IX ( Soviets got 1,183 LF. IXs and 2 HF. IXs), 610km/h for 109G-2, 593 for 109G-2/R6 and 588 for Fw 190A-4.

 

[thedab]

I got this for the G-2 A-4

that A-4 don't look right it should be about 630km/h on 1.42 ata

5000m is about 16400ft and 618km/h is 384mph it look like could be the mkIX with the 61Merlin Spitfire F. Mk. IX BS.428

 

[GregP]

I've seen some acceleration charts before for a range of aircraft, can't recall where just now. The charts indicated the fastest-accelerating aircraft was the P-38, at least up to it's top speed. The Spirfire was right there, too. The thing is the "excess power" available for the Spitfire is extremely dependent on mark. The Mk XIV had considerabley more excess power than the Mk V. As I recall the charts didn't delineate the specific variants of the aircraft depicted in the charts, so while they were very interesting, they were next to being practially useless. Without the specific variants, the power used, the test conditions, and the fuel used, who is to say whether or not the results were intentionally skewed?

Likewise aircraft "turning circle" charts are equally useless since variant, fuel, test weight and such are not specified. I notice the A6M Zero never seems to show up on these types of charts ...

We COULD rather easily come up with a spreadsheet for power to weight ratio for various planes and variants, but I can't post an Excel file in here. And I've noticed that people tend to go off when we specify some power point used from a pilot's manual. There are invariably several posts where somone claims the real MAP and power was some arbitrary higher value that was made OK in some vague memo that nobody can find except the guy claiming the memo exists.

Then there's the guys who argue that some power-to-weight ratio that is very small bit higher wins. In point of fact, when the ratio gets into even one unit in the first decimal place, the Cd, test weight, condition of the engines and prop, and probably the fuel make more difference than a power-to-weight delta of 0.1 over and above some other aircraft.

I have a spreadsheet with over 1,100 entries for piston-powered WWII aircraft and could throw that together rather easily, but I still can't post the file. When Excel files become acceptable, I'll gladly share the numbers for power to weight ratios for a wide range of aircraft and everyone can draw their own conclusions. The power-to-weight ratio is a very good place to start but is not the sole indicator of acceleration and climb performance, but that's just personal opinion. A pilot can shove the throttle fully forward, but if the mixture isn't just right and if the radiator doors and cowl flaps aren't properly configured, and if the plane took off from a muddy field into a swarm of bugs, then the acceleration and climb could vary considerably.

 

[Greyman]

Quick and dirty graph from Comparitive Performance of Fighter Aircraft

The British (AFDU I believe, I'd have to double check) rated the Spitfire IX better in acceleration than the Typhoon, the P-47C and the P-38F.

 

[GregP]

Thanks Greyman!

When my PC died I lost about 5+ years worth of neat link. This was one of them.

Since the Tempest is in the fray, forget the P-38F and go with the J or L.

 

[Aozora]

In August 1942 the Air Ministry issued a set of guidelines for Spitfire pilots facing the Luftwaffe, and the Fw 190 in particular, while flying over France and the Low Countries; amongst other things it notes the poor acceleration of the Spitfire from low boost and revs (Price notes in the intro that it could take 2 minutes to accelerate from low speed cruise to maximum speed, which could literally be a lifetime during combat): (also, page 2, para 5)

 

[GregP]

Thanks Aozora, good info ...

Wonder why they think the acceleration of the SPitfire is rather poor?

 

[Greyman]

'Relatively' poor - I would assume they're comparing the Spitfire in this instance to the German machines.

 

[GregP]

I'd believe that, Greyman, relative to something like a late Bf 109G or K, but the contemporary Spitfire versus a Bf 109F or early G-model would not seem to be at any disadvantage and would almost certainly out-accelerate an E model if any were still around.

But in the context as written, your conclusion is quite valid. I might have to look at the German power-to-weight ratios again. I already knew the Bf 109 had a great engine for the small airframe, but thought the power would not result in a power-to-weight ratio significantly better than the Spit. I could be wrong there. Some investigation is indicated ...

 

[Shortround6]

Without actual times for acceleration from speed XXX to speed YYY at altitude ZZZ a lot of this is guess work.

I also rather doubt that any fighter could go from 200mph cruise to 375-400mph in a lot less than two minutes (one reason P-51s cruised at around 300mph and weaved over the bombers).

Acceleration also changes with speed as there is a lot of extra power at slow speed and not a lot of drag while at high speed (and that varies with year, 350mph being fast in 1940/41 and 400mph+ being fast in 1943/44) there is less extra power and a lot more drag.

A bit like cars, acceleration for 20mph to 50mph or from 60mph to 90mph, which takes longer?

And depending on engine and altitude even in the same airframe. MK IX Spit with a Merlin 66 or a Merlin 70 at 1000ft or at 30,000ft?

 

[pbehn]

Surely by the time the merlin Spitfires acceleration was considered poor it shouldnt have been in service. The Typhoon should have replaced it as should the Griffon Spitfires both planes and their engines took time to sort out. The later model Merlin Spitfires were making the best of a bad job.

 

[thedab]

Well above 19,000ft the Merlin 45,was geting a bit out of breath, with it single-speed supercharger, where the BMW 801D with it two-speed
supercharger was still knocking out 1440PS,and the DB601E had a superior altitude performance as well.

So the mkV would be at a disadvantage,when it come to power at high altitudes, and would have a relatively poor acceleration compare to
the German machines.

Also you can see why the mkV seem to do a lot better in the Med, where the air battles were at lower altitudes, and why the mkIX with
the Merlin 61, was such a big deal.