Long range, high speed Spitfire fighter: the best approach?

[tomo pauk]

The Spitfire was one of the best known planes ever, and, especially in the UK, it is still regarded as the best fighter of ww2 by many. However, it was not good in some things: the fuel tankage was modest, even with changes introduced mid-war, and (with Merlin engines, ie. most of the examples produced) it was 'only' as fast as LW opposition, unlike the similarly-engined P-51B/C/D/K.
So what would be your take: what changes to introduce, in order to push the Merlin Spitfire beyond, say, Ruhr, while gaining some speed (in 20000-35000 ft altitude range, focus being 25-30000 ft) in process? We need the plane to be fielded in May/June 1943 at least.

 

[drgondog]

Laminar flow wing to reduce profile drag by 30%.

Greater sloped flat glass windscreen to further reduce stagnation Drag (as it did later)

Aft fuselage tank

 

[KiwiBiggles]

Aft fuselage tank

Given the Spitfire's longstanding CoG issues, an aft fuel tank would have been a complete non-starter. In fact, moving the engine forward 18" would have allowed more tankage, and would have improved the CoG range.

And if you then really wanted to retain the Spit's marginal longitudinal stability, I guess you could then chuck in an aft tank.

 

[gumbyk]

Laminar flow wing
Engine cooling system similar to the mustang
fully faired wheel wells.

Then start looking at increasing fuel tankage.

 

[davebender]

You can only cram so much internal fuel into that small airframe. Start with a clean sheet of paper just as Messerschmitt did when they designed Me-309 airframe to hold 770 liters of internal fuel, almost twice as much as Me-109. Larger airframe would also be a better fit for RR Griffon engine just as larger Me-309 airframe was a better fit for DB603 engine.

 

[Tante Ju]

Take a Mark VIII and heck saw. Saw off about 3 feet from each wingtip, and wrap it up in a way you find aesthetically pleasing.

Some duct tape over the undercarriage well wouldn't hurt either.

 

[bob44]

Redesign the wings for less drag, carry fuel similar to P51, redesign the cooling scoops similar to P51, clean up the fuselage, if possible add aft fuel tank?

 

[dobbie]

I think you would have ended up with a different fighter than the Spitfire. As it was designed as an interceptor, there would be far too many necessary changes in order to turn it into an escort type aircraft. However, Id love to see what the result would be!
If modifying the Spit is the only option, maybe laminar flow wings and as to the fuel tankage, possibly a wet wing? Its either that or stretch the fuselage to incorporate a fuselage tank, either ahead or behind the pilot.

 

[gumbyk]

I Know! We could call it something different too! Like "Spiteful"

 

[davebender]

Probably end up with a lemon, tarnishing the otherwise stellar Spitfire record as a lightweight fighter aircraft. Is that what we want?

 

[nuuumannn]

Probably end up with a lemon, tarnishing the otherwise stellar Spitfire record as a lightweight fighter aircraft.

Not really, I mean, look at what was actually done with it. The centre fuselage section from Frame 5, the firewall to Frame 19, the diagonal where the tail section joins was the same in every Spitfire/Seafire mark from the V to the Seafire 47, with either a cut down or high back rear fuselage. Any number of mods to engine, wing to which the undercarriage was fitted, and tailplane could be incorporated. Altering the fuse to take increased tankage might be a bit difficult and stretch the "Spitfire" legacy a bit much, hence the Spiteful being renamed. The Mk.21 was going to be renamed because of the vast differences between it and previous marks, but its centre fuse was the same and the name stuck.

This is a Mk.21.

 

[wuzak]

I think forget the laminar flow wings. Just concentrate on good surface finishes all over, fix the windscreen rake, add fuel somehow - in the wings if possible, in the rear fuselage. The Mk XIV and 21 had longer noses despite having a shorter engine - I presume mire fuel was stuck in the difference?

The opportunity to do more wing tanks was available with the Mk 21 wings. There were small tanks in the leading edges between the fuselage and the cannon bays. Why not outboard the cannons? In early Spits the 4 x 0.303" bays were in teh way, but not for the 21.

Tidy up the radiators. They did use the Meredith effect, and they did have boundary layer splitters. Just needed some work on volumes and input and output areas, plus a flap that was more adjustable (most had 2 positions on the Spits, IIRC).

May not be as fast as a laminar flow wing model, but it would be fast enough and would retain the Spitfire's handling qualities.

 

[gumbyk]

I think forget the laminar flow wings. Just concentrate on good surface finishes all over,

Why wouldn't you use them?

There is a reason laminar flow aerofoils are in popular use. They work.

 

[wuzak]

Why wouldn't you use them?

There is a reason laminar flow aerofoils are in popular use. They work.

The Spitfire's wing worked quite well.

The Spiteful's laminar flow wings helped it go faster (it also had different rads), but it wasn't as well liked as the Spitfire.

 

[gumbyk]

The Spitfire's wing worked quite well.

The Spiteful's laminar flow wings helped it go faster (it also had different rads), but it wasn't as well liked as the Spitfire.

It was the low thickness to chord ratio that helped it. now, keep that, and the plan-form, but introduce a laminar aerofoil section, and IMO you'd have a better wing.
Or, the ability to increase wing thickness, and actually be able to fit things like wing cannons into the wings, without having the bulges.

 

[Aozora]

Why wouldn't you use them?

There is a reason laminar flow aerofoils are in popular use. They work.

The laminar flow wings designed for the Spiteful/Seafang were a pig to get right, with lots of airflow problems around the ailerons, and the bugs were never really ironed out because by 1945 jet aircraft promised better performance. It may well be that successful laminar flow wings could have been designed for the Spitfire had Supermarine consulted with NAA and NACA, but that's pure speculation.

 

[Jabberwocky]

All sorts of stuff.

Minor changes:

1. Fully enclosed wheel wells (tested in the Mk III)
2. Retractable tail wheel (happened in the Mk VIII)
3. Fully flush riveted construction (happened in the Mk VIII)
4. Leading edge fuel tanks (happened in the Mk VIII)
5. Larger forward fuel tanks (happened in the Mk VIII)
6. Fit Hispano Mk V cannon (happened in the Mk 21)
7. Fit inboard .50 cal (happened in the Mk IXe)

Moderately easy changes:

7. Re-angle front windscreen and fit curved 'Speed Spitfire' window fairing (tested on the Mk XIV, showed 8 mph improvement in speed)
8. Fit 29 imp gal rear fuselage tank (happened in the Mk V)
9. Re-design the aircraft to use US-style aircraft fasteners (much lower panel gaps on US fighters)
10. Re-profile the nose skinning to Griffon-engine style 1 piece skin
11. Lengthen the nose profile slightly to add more fuel and aid the CoG issue

Difficult changes:

12. Reprofile the radiators to take better advantage of boundary layer and Meredith effect
13. Partially laminar flow wing

 

[parsifal]

what are laminar flow wings?

Range of the Spitfire did increase significantly with the Seafire 47 and a few other subtypes

 

[Jabberwocky]

The ultimate LR armed Spitfire would have been the Mk XVIII

This was a Mk XIV with some strucutral reinforcements and 188 gallons of internal fuel. That's 221% of what the Mk I through IX had.

Of course, the Mk XVIII also weighed more empty than the Spitfire Mk I did fully loaded.

 

[OldSkeptic]

Given the Spitfire's longstanding CoG issues, an aft fuel tank would have been a complete non-starter. In fact, moving the engine forward 18" would have allowed more tankage, and would have improved the CoG range.

And if you then really wanted to retain the Spit's marginal longitudinal stability, I guess you could then chuck in an aft tank.

Those CoG issues were largely sorted out in mid-late 41. Firstly by a temporary expedient of bob weights added to the elevator control line, later by redesigned elevator horns.
The CoG became even less of an issue with the 60 series engines (being longer and heavier) and of course even more so the Griffon.

With a rear tank(s) (actually fitted to late model IX, XVI and XIV Spits) of ranging between 66 and 75 gallons (imperial) the Spit was unstable, but so was the Mustang with its rear tank full.
The key was to burn that off first on climbs and cruise. Then it became a normal Spit again.

My calculations, based on a Mk VIII, with the leading edge tanks, showed a combat radius of 500 miles (= Berlin) was quite possible.

Jeffery Quill (the great Spit test pilot) did an example flight, which he documents in his book. Mk IX, rear tank, 90 gallon drop tank and a bob weight on the elevator control line. Flew to the North of Scotland and back with no issues (same as a Berlin round trip).

In fact you could squeeze a little more of out the Spit VIII for long range missions by, removing the 4 x .303 guns and adding another 26gallons (13 in each wing) in additional leading edge tanks.
The USAAF also flew 2 Spits across the Atlantic with modified Spits, with Mustang like double drop tanks in each wing.

There was no technical issue with a LR Spit (as I have shown before here), not a Mustang though as that was was really a VLR plane.

The range issue is about, after you have a stable aircraft and you have dropped your external tanks, how much fuel do you have left for combat and returning?
In my calculations I allowed a 15min combat time and cruise to Berlin and back.
Obviously shorter ranges would have allowed longer combat time, though ammo would have been the key issue then.

Link to late model Mk IX/XVI models 66 (imperial) gallon rear tanks: http://www.spitfireperformance.com/spitfire9-fuelsystem-lr.jpg