How The Spitfire Mk XIV Compared to the K4 and Other Questions

[mhuxt]

German fuel testing method:

View attachment Oppauer Method.PDF

German comparison of captured Allied fuels to German fuels (curve for B4 appears on "Exhibit 4a" tab). Source is an original German document in the Fischer-Tropf archives.

View attachment German Fuel Testing Oppauer Method.zip

 

[GregP]

Thanks mhuxt.

Where did you get the data? Not grilling, just wondering since my Google never found it ... BAD Google.

Main question ... what exactly is "OOZ," if I may ask? Octane ... something ...

 

[mhuxt]

Thanks mhuxt.

Where did you get the data? Not grilling, just wondering since my Google never found it ... BAD Google.

Main question ... what exactly is "OOZ," if I may ask? Octane ... something ...

Hi Greg,

OOZ is "Oppauer Oktanzahl" - Oppau Octane number. The method used to determine OOZ is described in the pdf report, unless I've uploaded the wrong file.

Original source data is a pdf of files recovered by the Technical Oil Mission, which is found at the Fischer-Tropsch (note spelling, I got it incorrect above).

Main page: Fischer-Tropsch Archive Click on "Technical Oil Mission Reels" to the left to get to the index. The data itself is in TOM-117-1001-1090 (that's reel 117, page range 1001-1090). The curves are amongst the last pages of the file.

 

[Milosh]

Spitfire site, Spitfire - Main

Now if one wants to be nostalgic and have a good laugh, Kurfürst - Articles - Notes for "Spitfire Mk XIV versus Me 109 G/K A Performance Comparison"

 

[Greyman]

Reading the opposing pages does it not indicate II./JG 11 used 1.98 ata?

 

[Milosh]

Reading the opposing pages does it not indicate II./JG 11 used 1.98 ata?

It was the operational test unit for 1.98ata K-4s. It was also only a staffel of 12 a/c not the whole Gruppe.

 

[stona]

Here's a simple question. Which would you choose to fly to give yourself the best chance of surviving?
For me it's a no brainer
Cheers
Steve

 

[Milosh]

Here's a simple question. Which would you choose to fly to give yourself the best chance of surviving?
For me it's a no brainer
Cheers
Steve

Why would you pick the K-4?

 

[stona]

Why would you pick the K-4?

Very good....but that shows it's a no brainer for you too

Is there anyone who would choose the K-4? I'd love to see their reasons for doing so.

Cheers

Steve

 

[spicmart]

The K-4 looks better and meaner.

 

[spicmart]

The Spitfire was reported to have been a He-man's aeroplane as far as stick forces in the high speed realm are concerned. That's why they gave it a new wing as featured in the 21 - 24. So why would the K-4 has higher stick forces?

 

[spicmart]

And what do stick forces, especially ailerons' depend on and how can they be improved?

 

[Kryten]

Both the Spit and 109 suffered overly heavy stick forces at high speed, the problem for the 109 was the cockpit did not allow the pilot the room to overcome the weight!

 

[Greyman]

Was the 109K improved over the 109G in this respect?

The 109G-6 tested by the AFDU against a Spitfire IX and XIV found both Spitfires superior over all speed ranges.

 

[parsifal]

Uh, who are we talking about here?

Kurfurst You either luv him or hate him, but impartial he aint, and he had an annoying habit of accusing anyone who opposed him of either biased, stupid or both.

I will never forget the debate in this place about how, allegedly, not a single tiger was lost in combat conditions in Normandy.......

But, having said all that, his knowledge on things 109 is pretty formidable, and for that I respect him.

 

[thedab]

even on 1.80 ata the K-4 has a better power to weight ratio to the mkXIV,and yet it slower and don't climb as well,if you think about it,for that P/W ratio,it's performance is pretty poor.

could this be down to it 3-blade prop?

 

[parsifal]

Very good....but that shows it's a no brainer for you too

Is there anyone who would choose the K-4? I'd love to see their reasons for doing so.

Cheers

Steve

I could be a cad and say the K-4 because it was mostly on the ground rather than in the air......

 

[Koopernic]

even on 1.80 ata the K-4 has a better power to weight ratio to the mkXIV,and yet it slower and don't climb as well,if you think about it,for that P/W ratio,it's performance is pretty poor.

could this be down to it 3-blade prop?

Maximum speeds must always be specified with the altitude at which they occur. The Sptifire XIV had a two stage intercooled supercharger that lost less power at high altitude (about 25000ft) and was thus able to fly faster at that altitude because there air presents less drag.

Of all the single stage supercharged engines the DB605DB and DC had the best altitude performance since the Daimler Benz's engine used a high compression ratio rather than a high boost ratio to obtain power and efficiency leaving the supercharger disposed to provide altitude compensation rather than boost.

At sea level a Me 109K4 on C3 fuel with MW50 was faster than the Spitfire XIV on PN150 fuel both at 1.8 and 1.98ata. About 16mph for the latter. Some of the post war boost ratings of the Griffon might have eliminated this gap.

The Me 109K4 in good condition with retractable tail wheel and with the undercarriage wheel doors fitted might manage 444mph on 1.98ata and also at 1.8ata, the difference being that at 1.98ata the speed was higher below the superchargers full pressure altitude.

Propellers can be optimised to produce their best 'thrust' at either low, medium or high speeds. By fitting a 'thin' propeller optimised for high speed the Me 109K4 could achieve around 454 mph at a slight cost in climb rate. A more advanced scimitar propeller was expected to achieve 460mph or more.

When the notification for rescinding of the 1.98 ata rating went out it noted that Me 109K4 reconnaissance units already being used at 1.98ata could be run to 1.9ata until they failed but must then be run at 1.8 ata. No problems were noted in engine overheating or seizure. The problems were related to knocking and pre-ignition and make note of the need to retard the ignition (a classic measure to prevent knocking). This means that had the Germans had a supply of a better fuel (105/135 say) they probably could have run those engines at 1.98ata. Alternatively a cooler running spark plug.

The Me 109K14 had the DB605L engine, essentially at two stage supercharger version without intercooler. With this engine running at 1.75 ata and a new 4 blade prop to gain purchase in thin air the aircraft had a speed of about 454mph at 31000ft. This is not down on the Spitfire Mk XIV but this did not enter service.

The Spitfire XIV still had the old wing developed for the Mk VIII wing and so aero elastic twist at high speed reduced its roll rate response. The new stiffer wing with balance tabs only came in on the Mk22. The Me 109K4 did not have as significant an aeroeleastic twist problem but had stiff ailerons at high speed due to compressibility, it could still be rolled. The solution was to be spring tabs or 'flettner' tabs to reduce force. Late war US navy fighters used these, so did several axis aircraft. I have my doubts about them and believe hydraulics was the only way to go.

If you were involved at a sea level fight a Me 109K4 was a bit faster. The Tempest V was the RAF's low altitude specialist.

The Luftwaffe was in the process of replacing the Me 109K,Fw 190A with jets and the Focke-Wulf 190D series and the Ta 152B,C and H.

Hence the question is a little displaced. The Me 109 belongs in the Hurricane era, perhaps the question should be 'what is better a Griffon or Merlin 66 powered Hurricane or a Me 109K4.

In some scenarios this might have happened.

 

[Edgar Brooks]

The Spitfire XIV still had the old wing developed for the Mk VIII wing and so aero elastic twist at high speed reducer its roll rate response. The new stiffer wing with balance tabs only came in on the Mk22. .

The "new" wing was actually introduced on the Mk.21, which (just) saw service in 1945. The XIV was wanted for high-level interceptions, which is why the only clipped-wing version was the low-lever P.R. F.R.XIVe, and the C.O. of 11 Group refused to have the extra fuselage fuel tank (as fitted to the XVI) because it slowed the rate-of-climb too much.

The Me 109 belongs in the Hurricane era, perhaps the question should be 'what is better a Griffon or Merlin 66 powered Hurricane or a Me 109K4.
In some scenarios this might have happened

There was never any chance of a two-stage Merlin, or the Griffon, being fitted in the Hurricane; Camm wanted to, but was told to forget it, due to the major airframe modifications, and concentrate on the Typhoon/Tempest.

 

[Koopernic]

The "new" wing was actually introduced on the Mk.21, which (just) saw service in 1945. The XIV was wanted for high-level interceptions, which is why the only clipped-wing version was the low-lever P.R. F.R.XIVe, and the C.O. of 11 Group refused to have the extra fuselage fuel tank (as fitted to the XVI) because it slowed the rate-of-climb too much.

There was never any chance of a two-stage Merlin, or the Griffon, being fitted in the Hurricane; Camm wanted to, but was told to forget it, due to the major airframe modifications, and concentrate on the Typhoon/Tempest.

The Spitfire F.21 did some patrols against midget subs in March 1945. Clearly the F.21 was a better aircraft than the K4 but it was likely to ramp up production a little slowly though the Mk XVIII (essentially an improved Mk XIV)would have supplemented it around April/May 1945. The Spitfire was also in its swan song era, not much less than the Me 109, as the jets began outclassing it.

If Supermarine lost its talented designer earlier and there was no Spitfire perhaps a Merlin 66 Hurricane might have been developed.

Me 109K4 production rate was explosive but only from October 1944, the Me 109K1/K2 which might have seen service in late 1943 or early 1944 had been delayed in an attempt to harmonise production across factories. It probably would have been 10 mph faster than the Me 109G14ASM. Mk XIV production rate was rather modest though service began in Feb 1944.