How far could you get a Spitfire XIV/XVIII to go?

[wuzak]

The Spitfire XIVE had 142.5 UKG (171.1 USG/647.8l) of internal fuel.

The Spitfire XVIII had 175.5 UKG (210.8 USG/797.8l) of internal fuel.

If fitted with drop tanks, like the experimental IX the USAAF modified, could you get a XIV/XVIII to Berlin and back?

 

[Thorlifter]

According to this source....

Spitfire MkXIVe - refining the breed

...the XIVE had a range of 610 miles. My math says that gives it 4.3mpg. I don't know how many gallons the drop tanks hold, but let's just say they are 150 gallons. If it had 2, that is 300 more gallons of gas. At 4.3mpg, that is an additional 1290 miles for a total of 1900 miles.

Now I'm sure there are calculations for additional drag and weight that reduce the range, but I'm not that smart. Unless someone knows better than my simple math, that should give you a decent estimate for starters.

 

[wuzak]

Morgan and Shackalady have the range at 610 miles normal, and 960 miles max.

RAF auxiliary fuel tanks (the slipper type) cam in 30, 45, 50, 90 and 170 UKG.

The converted Mk IX used 62.5 UKG drop tanks, the largest P-51 drop tanks were 110 USG (91.6 UKG).

Not sure that the Spitfire wing could take any larger than that.

 

[Shortround6]

What matters is do you have enough fuel once the external tanks are gone to get fight for XX minutes and get back to England.

How much fuel you can carry outside does NOT matter.

The Data Card for the MK XIVat Spitfire performance is blank on the range section, however the Data Card for the MK 21 gives an estimate that 5 minutes of combat was worth 75 miles of range at most economic cruise and 55 miles at max cruise. The US generally figured a 15 minute combat allowance.

The next question is at what speed do you fly from Berlin back to the coast at?

Most economic speed altitude or somewhere between most economic and max cruise and with a bit more altitude?

 

[Shortround6]

Duplicate

 

[wuzak]

The AFDU thought that the Spitfire XIV could compete with the most numerous German adversaries (Me 109G and Fw 190A) even with the slipper tank in place and half full.

Conclusions
57. Even with the 90 gallon tank, the Spitfire XIV can equal or outclass the FW.190 (BMW.801D) and the Me.109G in every respect. Its main advantages remain the tight turn and maximum climb.

Would that affect range calculations much?

 

[Shortround6]

Perhaps 6-10% depending on size of the tank?

Flight manual for Spitfire XII says to deduct 6% fuel mileage for 30 gallon slipper tank.

Once again the problem is fighting for a number of minutes and then getting out of Dodge (Berlin) at a speed and altitude that doesn't leave you a sitting duck for every only slightly green German pilot from Berlin to the coast.

A P-40E could fly 645 miles using just 110US gallons of fuel so I would guess a later version with 3 drop tanks might make it in and out.
A P-47B-D with the 305 gallon tank could fly 685 miles on just 200US gallons of fuel.

Trouble is that to get those ranges they had to fly at 200-225mph between 5000 and 10,000ft.

A P-47B-D with the 305 gallon tank was supposed to be able to fly 880 miles after burning 40 gallons starting, warming up, taking off and getting to 5,000ft. Flying at about 200mph IAS and under 12,000ft. They were rated at a 125 mile radius once climb to 25,000ft,( P-47 could burn 40-50 gallons just climbing from 5,0000ft to 25,000ft) cruise at 305-315mph and 15 minute combat allowance and small allowance for finding the home field was figured in.

Once you are over the Channel/North Sea you can slow down to best economy speed but until then ????

Difference between 10 minutes at combat rating and 15 minutes could be around 60-70 miles or 15 minutes as most economic looking for air airfield in clouds/fog?

 

[Greyman]

Official Data Sheet for the Spitfire XIV (Griffon 65) says:

-	Permanent Tanks	30 gall. Drop Tank	90 gall. Drop Tank
Fuel Carried (gall.)	112	142	202
Allowance (T.O. climb to 20,000)	25	26	27
Range (miles at most econ. speed)	460	610	850
Range (miles at max cont. cruise)	350	470	690

Combat Allowance for every 5 min at combat rating (2,750 rpm +18lb) reduce above ranges by:

75 miles at most econ. speed
55 miles at max cont. cruise​

 

[Greyman]

Official Data Sheet for the Spitfire XIV P.R. (Griffon 65) says:

-	Permanent Tanks	90 gall. Drop Tank
Fuel Carried (gall.)	257	347
Allowance (T.O. climb to 35,000)	44.5	47
Range (miles at most econ. speed)	1,260	1,650
Range (at 350 m.p.h.)	1,100	1,460*

Combat Allowance for every 5 min at combat rating (3,000 rpm +18lb) reduce above ranges by:

65 miles at most econ. speed​

* first 300 miles at 30,000 feet

 

[wuzak]

Official Data Sheet for the Spitfire XIV (Griffon 65) says:

-	Permenent Tanks	30 gall. Drop Tank	90 gall. Drop Tank
Fuel Carried (gall.)	112	142	202
Allowance (T.O. climb to 20,000)	25	26	27
Range (miles at most econ. speed)	460	610	850
Range (miles at max cont. cruise)	350	470	690

Combat Allowance for every 5 min at combat rating (2,750 rpm +18lb) reduce above ranges by:

75 miles at most econ. speed
55 miles at max cont. cruise​

Some versions of the XIV had a rear fuselage tank which increased internal fuel to 142.5 UKG. So, I would assume that gives 610 miles (or slightly more) at most economical cruise.

Taking off the combat allowance therefore would mean that Berlin was out of the question.

The F.XVIII had even more fuel in the rear fuselage, for a total internal fuel amount of 175.5. By extrapolation, the F.XVIII would have a range of 721/548 (most econ/max cruise) miles on internal fuel.

I assume that the XIV could have had the extra rear fuselage tankage?

 

[Greyman]

(ii) F.R. Mk.XIV aircraft:
An additional tank of 31 gallons capacity is fitted in the rear fuselage behind the cockpit.

...

NOTE.- Except for special operations, as directed by the appropriate Operational Commander, the rear fuselage tank is sealed off and is not to be used.

...

General flying

(i) Stability:

...

(b) The addition of rear fuselage tank fuel impairs longitudinal stability and with this tank full the F.R. Mk.XIV aircraft should not be flown above 15,000 feet.

 

[wuzak]

The FR.XIV also had cameras back there, moving the CoG rearwards.

 

[Shortround6]

Official Data Sheet for the Spitfire XIV (Griffon 65) says:

-	Permanent Tanks	30 gall. Drop Tank	90 gall. Drop Tank
Fuel Carried (gall.)	112	142	202
Allowance (T.O. climb to 20,000)	25	26	27
Range (miles at most econ. speed)	460	610	850
Range (miles at max cont. cruise)	350	470	690

Combat Allowance for every 5 min at combat rating (2,750 rpm +18lb) reduce above ranges by:

75 miles at most econ. speed
55 miles at max cont. cruise​

Thank you.

as a rough estimate let us say that our MK XIV gets to Berlin with 160 gallons aboard. (increase internal tank, 1/2 full 90 gal slipper tank, what ever) fuel to get to Berlin being supplied by under wing fuel tanks that are dropped. 10 minutes of combat (not 15min) will take about 27 gallons of fuel, leaving 133 for the trip home. It is 377 miles (or so) from Berlin to Leiden on the Dutch coast and running at a speed that splits the difference in fuel consumption between max cont. and most econ. gives about 4.65mpg and uses 81 gallons of fuel. This leaves 52 gallons but the plane can slow to most econ. for the over water portion. It is 138-141 miles from Leiden to Norwich/Ipswich and at 5.25mpg that takes about another 26 gallons leaving about 26 gallons in the tank.

It looks 'Possible' but still may be a bit iffy as to being practical. Leaving aside how the plane would fly with a pair of 60 gal under wing tanks (roughly)in addition to the extra 48 gallon over normal tankage this "estimate" makes no allowance for headwinds coming back from Berlin, no allowance for finding and orbiting home field/s unless that was included in the data sheet? it also is flying almost a straight line with only a slight dog leg. It also uses 10 minutes at combat power, using 15 minutes of combat power could put you over the Ipswich/Norwich line with about 13 gallons in the tank/s which might be enough for 20 minutes or a bit less at most economical.

Anybody want to poke holes at it

It looks a bit thin to try on a regular basis. Please note that is pretty much a straight fly to Berlin, drop theoretical wing tanks, fight for 10-15 minutes and head straight back to England. Not the most realistic or practical combat mission as it also makes no provision for actually escorting bombers or rendezvousing with them.

 

[drgondog]

Internal fuel is what matters to USAAF Combat radius calculations and planning.

 

[RCAFson]

Official Data Sheet for the Spitfire XIV (Griffon 65) says:

-	Permanent Tanks	30 gall. Drop Tank	90 gall. Drop Tank
Fuel Carried (gall.)	112	142	202
Allowance (T.O. climb to 20,000)	25	26	27
Range (miles at most econ. speed)	460	610	850
Range (miles at max cont. cruise)	350	470	690

Combat Allowance for every 5 min at combat rating (2,750 rpm +18lb) reduce above ranges by:

75 miles at most econ. speed
55 miles at max cont. cruise​

There was also a 170G slipper tank which would have extended range at econ cruise to about 1150 miles:

http://www.spitfireperformance.com/spit21ads.jpg

the Spitfire 21 had very similar range figures, but carried a bit more internal fuel.

 

[OldSkeptic]

Oh, pretty easy, for a Mk VIII simply put a 66 UK gal rear tank in and a 90 gal drop tank. Slap on some bob weights in the elevator control lines and you are fine.

Yes on take off and climb you are in a out of CoG situation (but so was the Mustang), so burn off the rear tank first, then the drop tank, then main and wing tanks for combat and return. I did a spreadsheet ages ago using official data card figures for the VIII and got a combat radius, with 15 mins of combat time, of 500 miles with a 15 gal reserve.

If you leave 10 gals in the rear (CoG fine at that) then you have a 25 gal reserve, which means a combat radius of 550-600 miles.

Technically there was no real problem. In fact late model Mk XVIs actually had a rear tank fitted.

To work out why it wasn't done you have to look at internal politics within the RAF. Portal had hung his hat on the position (for years) that a LR escort fighter was impossible Even as late as Oct '43 he was writing to Arnold (and telling Churchill) saying it couldn't be done (yes just as the P-51B was deploying).

When the Boss says 'No' it is not going to happen….

 

[Aozora]

These are the relevant pages from the Spitfire XIV/XIX Pilot's Notes: note the recommendation for F.R. XIVs fitted with rear fuselage fuel tanks that the pilot not fly above 15,000 ft with the full tank.

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Recommended cruising speed for maximum range = 200-210 mph I.A.S; engine speed = 1,800 R.p.m minimum:

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[Koopernic]

The photoreconnaissance variants of the spitfire carried enormous quantities of fuel in the wing leading edges, they carried more than double the fuel in the wing adding about 115 gallons with it the two stage Merlin powered variants had a range of over 1350 miles. Much more than the Mustang. With drop tanks PRU Spitfires undertook missions all the way to the North Baltic coast, some 2500 miles was possible.

Hence this is what I would do:
1 Take a photoreconnaissance Spitfire, remove cameras, add back bullet proof windshield and other equipment. Not too much needed, as we are not attacking bombers only enemy fighters.
2 Install a pair of 'gondola' style canon similar to that on the Me 109 under each wing. A pair of Hispano is enough for an escort fighter.

Data on the effect of these 30mm gondola guns on the Me 109G6 is not hard to find. The speed reduction at sea level was only 6km/h (3.6mph) when flying at 528mph at sea level. That's a 1.2% reduction in speed.

The Gondolas were disliked not because of their effect on speed but on climb and probably some handling issues due to weight and roll rate.

The Spitfire would hardly be effected at all I would imagine as it is not adding armament only slightly relocating it.