Why the heck did they design it that way?
- Thread starter michael rauls
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wuzak
Captain
The 2 stage Merlin was 250-300lb heavier than the single stage versions. It was also more powerful than the earlier versions. This is why the structure was strengthened.
http://www.wwiiaircraftperformance.org/Spitfire_VIII_Tactical_Trials.pdf
Tactical trials between a IX and VIII (with extended wing tips) showed only small advantages for each - the VIII for speed over 30,000ft, the IX for climb rate at low altitudes. The biggest difference was in roll, where the extended wing tips and smaller ailerons on the VIII were detrimental.
But most production VIIIs had the standard wing tips, so performance would be very close.
Shortround6
Major General
Lockheed Super Electra first flight July 27th 1937.
There were a number of other flap designs.
I meant the rate of progress S/R, look at all the planes in production and on the drawing board in Sept 1939 and compare the same in Aug 1945.
MiTasol
1st Lieutenant
Verry enlightening answers to things I have wondered about. I'm sure there are many more examples like this like leaving the supercharger off the p39 or p40 but I want to leave at least a few picks for others.
The P-39 and P-40 both have superchargers.
They do not have turbochargers although the P-39 was designed with one.
MiTasol
1st Lieutenant
To fit that extra ten gallons in a Spitfire main tank means making the tank longer and leaving out all the instruments and maybe the instrument panel. Pilots are known to bitch about various things and in this case it I think it would definitely be warranted.
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- #67
michael rauls
Tech Sergeant
- 1,679
- Jul 15, 2016
Sorry i was referring to not upgrading to a two stage supercharger latter on when it was available. Guess I drastically missworded that. My bad.
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- #68
michael rauls
Tech Sergeant
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- Jul 15, 2016
Could this not have been located behind the cockpit ala p51( an honest question not a retorical one). Might have caused some handling issues with the rear tank full like again the 51 but if this were used up in warm up/ take off the same way then the benefits would seem to out way the downside no?
There was a rear tank in some spitfires, it had the same issue as on the P-51. However this wouldn't solve the problem. The P-51 was faster on maximum speed, but it was also faster when cruising, on the same engine setting it was 30mPH quicker which is a long way on a 6 hr mission much of which is cruising. The Spitfire could use external slipper tanks of varying sizes, but the bigger the tank the more performance was affected, with the biggest slipper tank it was possible to fly to somewhere you cannot fly back from.
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- #70
michael rauls
Tech Sergeant
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- Jul 15, 2016
So if I understand that corectly 10 gallons additional on a spitfire would not be enough to materially impact combat radius at least in some part due to a lower cruising speed as compaired the the p51 for instance. And just continueing on with the same lime of reasoning here, I'm guessing a maybe a larger tank mounted in the same manner would cause unacceptable instability issues on take off?
Cruising a Merlin uses 50 gals/hr, at maximum it uses 150galls hr. (as ball park figures). So it gives you an extra 12 minutes cruising or 6 minutes range about 25 miles.
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- #72
michael rauls
Tech Sergeant
- 1,679
- Jul 15, 2016
Seems an extra 12 minutes could have been more than useful in some situations or maybe say 18 minutes with a slightly larger tank if that was doable without causing to much of a instability on take off issue? but I suppose as was said earlier you have to draw the line somewhere with the fuel thing and guys alot smarter than me drew it where they thought it should go. I just can't help but think what an extra18 or even 12 minutes might have meant in alot of situations in a plane with a limited combat radius.
The other side is what missions would a long range spitfire do? The RAF didn't have a suitable day bomber. A fighter doesn't do much damage on its own and in any case the Mustang MkI was ordered by the British who received 500 of them, they also had Typhoons to shoot up locos in France.
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- #74
michael rauls
Tech Sergeant
- 1,679
- Jul 15, 2016
Agreed. I think its fair to say, ya a little more endurance would have certainly been useful in some situations but you can't expect guys at the drawing board years earlier to envision every possible future situation especially when the mission profile they had in mind when designing the spit was not one that requires a particularly long range. So now I have a much better idea " why the heck did they designed it that way" Thanks!
Shortround6
Major General
You also have to remember that when many of these aircraft were designed (pencils/pens put to paper) self sealing tanks, armor and BP glass were not required.
These added hundreds of pounds to fighters and often resulted in smaller fuel tanks. In some cases in 1940 the improvements in the engines barely kept pace with the increase inoperational weight let alone allowed large increases in fuel storage. Radio equipment was also added. For the British IFF so their own planes would show up on the ground radar as friendly is an often overlooked change.
These added hundreds of pounds to fighters and often resulted in smaller fuel tanks. In some cases in 1940 the improvements in the engines barely kept pace with the increase inoperational weight let alone allowed large increases in fuel storage. Radio equipment was also added. For the British IFF so their own planes would show up on the ground radar as friendly is an often overlooked change.
buffnut453
Captain
The problem here is that we're applying the retrospectroscope and expecting people in 1936 to know how long(er)-range fighter-bombers would evolve when no such thing existed in the 1930s.
All military procurement systems involve the levying of requirements for what is anticipated at that time. Sadly, our crystal balls aren't particularly effective and we often (usually?) find that we're fighting a different war than was expected. That's exactly what happened with the Spitfire. There was never any thought in the 1930s that bombers might need fighter escorts all the way from the UK to Berlin, nor was there any conception that a single-engine, single-seat fighter could carry a useful ground attack payload.
The Spitfire was designed to defend the UK mainland or, if necessary forward deploy (almost inevitably to France) for coalition defensive operations. In those envisaged roles, I think it excelled. Sadly, as we now know, that isn't the way WW2 developed but, to me, it is testament to R J Mitchell's design genius that the Spitfire remained a potent threat, increasing performance, payload AND range throughout its evolution. That's a pretty impressive achievement in my book.
All military procurement systems involve the levying of requirements for what is anticipated at that time. Sadly, our crystal balls aren't particularly effective and we often (usually?) find that we're fighting a different war than was expected. That's exactly what happened with the Spitfire. There was never any thought in the 1930s that bombers might need fighter escorts all the way from the UK to Berlin, nor was there any conception that a single-engine, single-seat fighter could carry a useful ground attack payload.
The Spitfire was designed to defend the UK mainland or, if necessary forward deploy (almost inevitably to France) for coalition defensive operations. In those envisaged roles, I think it excelled. Sadly, as we now know, that isn't the way WW2 developed but, to me, it is testament to R J Mitchell's design genius that the Spitfire remained a potent threat, increasing performance, payload AND range throughout its evolution. That's a pretty impressive achievement in my book.
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- #77
michael rauls
Tech Sergeant
- 1,679
- Jul 15, 2016
Yes thats one of the things that has always been kinda frustrating for me to read that for many types just as improvements in hp came along so would a wheelbarrow full of new required wieght
keeping them mired in never ending mediocre performance mud so to speak. Most of these things like self sealing fuel tanks certainly warranted the soaking up of new hp. However, although I can't remember any particular examples right now I reamember thinking of a couple weight additions" did they really need that extra 300 lbs for that". That might also be an interesting discussion i.e. modifications done to aircraft negatively affecting performance that ended up giving little if any benefit but i guess that would be another topic for another thread................
HmmmmmNo, it was willingly sacrificed in the workings of the Operational Requirements Committee.
Everything about designing a fighter is a compromise, and in the quest for speed and firepower it was endurance that was one of the the first to be compromised.
Cheers
Steve
Edit: Wasn't fuel capacity/endurance further reduced when Supermarine agreed to fit eight guns? (I can't remember). The requirement to lift a bomb definitely went, in lieue of more guns.
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- #79
michael rauls
Tech Sergeant
- 1,679
- Jul 15, 2016
I certainly hope to hear others inquiries/ picks to be answered or spontaneous explanations given of reasons things were designed the way they were( not nescesarily limited to things that appeared to be deficits, at least at first glance) as I for one find this topic fascinating and this thread was not intended to be a "one off" for the Bf109/ Spitfire. I can think of dozens if not hundreds of examples but don't want to Bogart the thread.
Seems like I hit a nerve here. That was not my intent.
To address your points though: The Mustang Mk.I actually should have been faster at low altitude but just could not break the 400 MPH mark at any altitude. The Mk.II P-51A could. I believe most of the very low production numbers served in CBI but I didn't realise we were restricting discussions to Europe.
Never said the Allison Mustang or Mustang in general was better than everything else.
The main point I was trying to make was that although the Spitfire was certainly a great fighter, it was relatively slow for the amount of engine power installed and the only other common aircraft with similar model engines was the P-51B/D. If you think about it, the Merlin Mustang had about the same speed advantage over the Spitfire Mk.IX as the Allison Mustang had over the P-40....
As I see it, in general, everyone has some kind of unusual feature in their fighter design: The Mid-Engine in P-39, Thin Elliptical Wings in Spitfire, Landing Gear attached to the Fuselage for Me 109. Sometimes the trade off worked and some times it did not.
Just to throw another Aeroplane into the pot: What do you all think of the relatively small wings on the Focke-Wulf 190 series?
- Ivan.
