Qualities that made for a great aircraft that don't show up in performance stats.

[XBe02Drvr]

Normally, in a low speed turning fight they would not be pulling a lot of G's.

They'd be pulling as much G as their power available could sustain. That's how you pull lead on your opponent. All this talk of wing loading and wing area and CsubL and slats misses the point. It's all a function of the effective thrust of your powerplant AT A NEAR STALL AOA compared to the L/D of your entire airframe AT THAT AOA that determines your performance in a turning fight.
The elliptical (Spitfire) wing approaches the ideal in this respect as its L/D is better at high AOA than just about any other wing shape. Add to that a slender fuselage with a sexy curvaceous bottom and its parasite drag rise with high AOA is less than most of the competition.
A plane of the same weight with a high aspect ratio straight taper wing (think 109) and comparable airfoil is going to need more effective thrust to match it in a turning fight, if both pilots are equally brave about nibbling at the edge of a stall, and both have comparable G tolerance. Now if one aircraft has automatic slats, that might effect the bravery balance.
Cheers.
Wes
PS: Note, I did not say engine HP. There's a lot more that goes into effective thrust, such as propeller efficiency, P factor effects, thrust line displacement with AOA, intake ram air reduction with AOA, etc.

 

[Schweik]

My point is that if you are going say 150 mph and turning tightly (such as while pulling lead), you are more likely to stall (and probably spin) before you build up very high G loads. I'm not a pilot and didn't fight in WW2. All I can do to learn about this experience is read a lot of first hand combat accounts, as I'm sure you have, and almost all of the reports of blacking out from high G load are from when turning tightly at high speed, such as while diving.

And I'm sorry, I don't agree. Wing loading does affect your turn rate, regardless.

In my opinion, especially with the Bf109 the lower the landing speed the better things are. The 109 was best landed in a three point landing, so slower the better as I see it

No doubt, better - but necessary? Like I said, I think they were landing the 109E's ok. I'm not even sure what we are debating at this point so I'll reiterate my claim - the slats helped in combat and I think that mattered significantly. I don't think they were just for landing in other words.

S

 

[pbehn]

No doubt, better - but necessary? Like I said, I think they were landing the 109E's ok. I'm not even sure what we are debating at this point so I'll reiterate my claim - the slats helped in combat and I think that mattered significantly. I don't think they were just for landing in other words.

S

In the interwar years there was a debate about what was the best way forward with monoplane design. Thin wings were known to stall easily but were obviously lower drag than thicker wings. The official line in UK was that thicker wings were best and Hawkers followed this, Mitchell at Supermarine had other ideas he produced a thin elliptical wing with washout. Willy produced his design which was a thin straight wing with slats and no washout. from wiki …..A fighter was designed primarily for high-speed flight. A smaller wing area was optimal for achieving high speed, but low-speed flight would suffer, as the smaller wing would require more airflow to generate enough lift to maintain flight. To compensate for this, the Bf 109 included advanced high-lift devices on the wings, including automatically-opening leading edge slats, and fairly large camber-changing flaps on the trailing edge. The slats increased the lift of the wing considerably when deployed, greatly improving the horizontal maneuverability of the aircraft, as several Luftwaffe veterans, such as Erwin Leykauf, attest.[24][25] Messerschmitt also included ailerons that "drooped" when the flaps were lowered (F series and later the lower radiator flap operated as part of the flap system), thereby increasing the effective flap area . When deployed, these devices effectively increased the wings' coefficient of lift. ………….. The 109 gained weight considerably during its life, it needed lift devices to cope with its increased weight. The 109 was the frontline fighter of the LW from the mid 1930s, the tactics and maneuvers that they used as routine were developed in the 109.

 

[GregP]

Regarding post #181 about the Bf 109 slats, they do NOT allow the Bf 109 to turn more tightly.

The slats are almost exactly 1/3 of the wing span distance, and they are located right in front of the ailerons. Their function is to keep the airflow over alierons attached and effective through the stall. Sure, the very small increase in lift will help a little in a turn, but hardly at all. On the other hand, you can have the main wing full-stalled in a Bf 109 and throw the stick back and forth, and the wings will follow the stick ... unless you keep pulling back harder, then everything stalls.

It makes firing from a Bf 109 at the ragged edge of stall a pretty good bet for some hits, since stalling the main wings does NOT mean the stab, elevator, and rudder are stalled.

Go measure the wingspan and then go measure the slats. It will become immediately obvious to the causal aerodynamicist. The wing flaps, however, could easily and quickly lowered as maneuvering flaps. All you had to do was to grab both of the adjuster-wheels (flap and elevator trim) and turn them as a unit, you got partial flaps and a complete elevator retrim, all in one easy to use package. Ingenious.

Would it bleed speed off using flaps? Yes. But it could also get you into or out of position to be fired upon or to fire on someone in an enemy aircraft.

If only they would have tweaked it to be a real 400+ mph fighter! Instead, it was a medium-speed fighter with the ability to go fast in relatively straight lines when the need arose.

 

[Shortround6]

If the design didn't allow for dramatic improvements to things like engines, increased fuel capacity, armor, more weapons and various other factors, it wasn't such a good design. That is one of the main traits that defined a good aircraft in WW2.

In fact per the thread title, it's probably one of the less obvious but most important traits of a good warplane - the capacity for improvement and modification, as a subset of overall versatility. That is the difference between a lot of the other 1930's designs like the Curtiss Hawk, I-16, MS. 406 and the Hurricane: they were pretty good in their day, and remained formidable for a few years, but ultimately didn't have room for the dramatic improvements needed for the rapidly accelerating pace of aircraft design and the swiftly soaring requirements for an expanded flight envelope for the ever more dangerous combat environment of WW2.

The Curtiss Hawk was better than the other other three at being developed. It also shows a bit of the difference that just being a bit bigger can bring.
The I-16 was the first monoplane fighter with retracting landing gear and there was only so far it was going to go. It's first flight was nearly two years before the 109 so they are not really contemporaries. Installed power more than doubled over it's life but adding another 10-20% more power to it in 1941/42 wouldn't have changed much.

The Hawk on the other hand did pretty good for a plane that flew over 6 months before the 109 (in May 1935), unfortunately it was saddled with a prototype engine that went nowhere and Curtiss began a mad scramble to get a good engine for it. It started life at a bit over 4800lbs but that might not include guns and the P-40Qs hit 9000lbs so it certainly exhibited quite a bit of stretch. It was up against newer planes in way the 109 wasn't. The US aircraft industry came up with more and better replacements than the German aircraft industry could. In large part just due to the shear size of the US industry. But that meant the US could stop production of the Hawk in 1944 because it had better planes in large scale production. Had the US been facing a similar situation to Germany perhaps more work would have gone into fitting better engines in the last year or two of the Hawks life.
The 109 lasted as long as it did for several reasons, one was that the intended replacements didn't work. See 209-II and 309. Another was that in 1943/44 Germany could not afford the loss in production that switching to a new fighter type would entail. Another was the type of combat had changed. While the US (and the British) were finding short ranged fighters a bit of an embarrassment in the type of missions being flown in late 1943 and 44 a short ranged/short endurance fighter was still very useful to the Germans as the allies were delivering targets (bombers) practically to the German fighter fields doorsteps.
The 109 was still a dangerous opponent to the allies and useful to the luftwaffe but it was no longer in front ranks of fighter design.

A bigger plane allows changes to be made in an easier manner. Adding 100lb of pilot armor to a 4400hp plane means a bigger impact to performance that adding 100lbs of pilot armour to a 5500lb plane for instance. double in the weight of guns and ammo on plane with a 230sq ft wing is easier than doubling the weight of armament on plane with with 170-185sq ft of wing.


A number of planes used slats and a number of planes used fixed slots which perform essentially the same function to maintain aileron control at near stalling speeds.

notice fixed slot behind wing leading edge in line with the front of the blue circle of the national insignia. Lockheed 14s/Hudson's/Venturas and even some B-24s used such slots.
as did the Douglas SBD

Some STOL aircraft use a full span fixed slot. Please note that neither the slots or slats increase wing lift on their own. They allow the wing to generate more lift by increasing the angle of attack without stalling. If the wing never exceeds an angle of attack of around 12-14 degrees (depending on airfoil and other things) a slot or slat does nothing except add a bit of weight and/or drag.

The use of slats/slots was a very common practice in the late 30s and early 40s but it was hardly an example of advanced thinking or design.

 

[pbehn]

Can I point out that while eking out the last drops of the 109s capabilities, Messerschmidt did have alongside it the Me262 which from June 1944 was the DBs of aviation at the time.

 

[XBe02Drvr]

My point is that if you are going say 150 mph and turning tightly (such as while pulling lead), you are more likely to stall (and probably spin) before you build up very high G loads.

If you're down to 150 and still haven't pulled enough lead to get a shot, it's time to bug out. A turning fight is not a steady state affair. Usually entered at a relatively high speed, it is generally a matter of diminishing airspeed and altitude as it progresses. If you haven't gained any nose to tail separation by two turns, it's time to go.

And I'm sorry, I don't agree. Wing loading does affect your turn rate, regardless.

Of course it does. It affects both the Lift side and the Drag side of your high AOA turning airplane, and consequently your turning radius. It's just not the sole determining factor some folks like to imply.
Cheers,
Wes

 

[Kevin J]

As I read "stuff" on the Bf109 wing, it wasn't a leap forward in technology to gain an advantage in aerodynamics and performance, it was an engineering compromise to maintain control at stall and be easy to produce. It was certainly better than the thick wings of the Hurricane in terms of speed, whether it was or wasn't better than the Spitfire is a debate that has been held many times. What is not debatable is that the Bf109 wing was easier to produce and also it couldn't contain weapons within it, which is what the engineering compromises and solutions were all about.

Well...
I'm Russian and now I have to learn something new about my mother tongue. Should I go back to grade school...

Did I get that wrong or was it that my woman was Chuvasha?

 

[pbehn]

Did I get that wrong or was it that my woman was Chuvasha?

No idea what your point is but the translation of brother sister and cousin are not the same in Russian, and Bf109 wings were easier to produce by a country mile than the spitfires were.

 

[XBe02Drvr]

and Bf109 wings were easier to produce by a country mile than the spitfires were.

And how! Just ask any Experimental Aircraft Association homebuilder who's tried to build a replica Spit. That ellipse is a fussbudget job to build.
Cheers,
Wes

 

[GrauGeist]

There is no word for cousin in the Russian language, your cousins are your brothers and sisters.

Interesting...

Even in Bulgarian, they have a word for cousin.
Actualy one for male cousin (Братовчед) and one for female cousin (Братовчедка).

 

[Schweik]

If you're down to 150 and still haven't pulled enough lead to get a shot, it's time to bug out. A turning fight is not a steady state affair. Usually entered at a relatively high speed, it is generally a matter of diminishing airspeed and altitude as it progresses. If you haven't gained any nose to tail separation by two turns, it's time to go.

Yes well, we aren't talking about F-18s here, getting down to 150 wasn't exactly uncommon in a WW2 dogfight, and you could only 'bug out' if your opponent(s) let you. Turning tail and running is the best way to line up an ideal target... for your enemy, or his wingman etc.

Doctrine, like plans, rarely survive contact with the enemy, and while it may be ideal to go after two turns, it routinely was not an option, as described by dozens of pilots on all sides in many different combat Theaters in WW2.

The other characteristic of WW2 propeller driven aircraft generally speaking is that they don't accelerate like modern jets on afterburner either, especially if a running fight has already ended up with aircraft down on the deck. So achieving separation could be tricky, even when desired ... sometimes they had to keep fighting until either victory or until all aircraft involved were low enough on fuel to be willing to let each other go.



The point being (to circle back to where we started) a low speed dogfight of the type where the slats could come into play did not necessarily result in pulling high G loads, as Shortround implied.

S

 

[Schweik]

The Curtiss Hawk was better than the other other three at being developed. It also shows a bit of the difference that just being a bit bigger can bring.
...
The Hawk on the other hand did pretty good for a plane that flew over 6 months before the 109 (in May 1935), unfortunately it was saddled with a prototype engine that went nowhere and Curtiss began a mad scramble to get a good engine for it. It started life at a bit over 4800lbs but that might not include guns and the P-40Qs hit 9000lbs so it certainly exhibited quite a bit of stretch..

I think it's a bit of a stretch to suggest that the P-36 and the P-40 were the same aircraft. Certainly they were related, but it's rather similar to saying the Blenheim, Beaufort and the Beaufighter are the same (despite similar dimensions and sharing many of the same jigs and so on, I would say they were at best cousins) or the LaGG -3 to the La 5 / La 7, and so on. Same lineage surely, but different aircraft.

 

[XBe02Drvr]

I think it's a bit of a stretch to suggest that the P-36 and the P-40 were the same aircraft.

Early P-40s were little more than Allison equipped P-36s. Brothers if not clones. Certainly closer than cousins.
Cheers,
Wes

 

[Schweik]

You can call them 'brothers' or 'cousins' but they aren't the same aircraft, sorry. If there is one thing i know pretty well it's the P-40.

 

[GrauGeist]

I think it's a bit of a stretch to suggest that the P-36 and the P-40 were the same aircraft. Certainly they were related, but it's rather similar to saying the Blenheim, Beaufort and the Beaufighter are the same (despite similar dimensions and sharing many of the same jigs and so on, I would say they were at best cousins) or the LaGG -3 to the La 5 / La 7, and so on. Same lineage surely, but different aircraft.

The P-40 was literally a P-36 with a V-12 mounted in it's nose. The XP-40 was the 10th P-36 off the production line that had it's radial removed and an Allison faired in.

In the case of the La-5, it was also literally a Lagg-3 with a Su-2's nose grafted on, complete with the Shvetsov ASh-82. Doing this also most likely saved Lavochkin's life, as he was not popular with Uncle Joe...

 

[Schweik]

Still not the same plane, in either case. By a long shot.

In terms of the P-40 especially when you are talking about actual combat variants, not transitional experimental aircraft.

 

[GrauGeist]

Perhaps it's time to revisit your literature?

Curtiss refined the XP-40 but made no real changed to the P-36 airframe tooling. The difference in wingspan between the P-36 and the P-40 was literally fractions of an inch. There was no significant between the P-36 and the P-40 from the firewall back.

So what "long shot" are we talking about?

Of course, from the firewall forward, there will be considerable differences, as the Allison required additional sheet metal and plumbing. But aside from that, there was no discernible difference. And this was in Curtiss' favor as they didn't need to stop production and retool for a new aircraft.

Lavochkin did the exact same thing with his La-5.

What happened with the later variants doesn't apply, were talking direct transitions from one type to the next at it's inception.

 

[michael rauls]

I always thought the p40b and c were almost identical to p36 from the firewall back. I've sure read that a few times( yes I known that doesn't nescesarily make it true). They do sure look the same .

 

[Schweik]

Perhaps it's time to revisit your literature?

Curtiss refined the XP-40 but made no real changed to the P-36 airframe tooling. The difference in wingspan between the P-36 and the P-40 was literally fractions of an inch. There was no significant between the P-36 and the P-40 from the firewall back.

So what "long shot" are we talking about?

Of course, from the firewall forward, there will be considerable differences, as the Allison required additional sheet metal and plumbing. But aside from that, there was no discernible difference. And this was in Curtiss' favor as they didn't need to stop production and retool for a new aircraft.

Lavochkin did the exact same thing with his La-5.

What happened with the later variants doesn't apply, were talking direct transitions from one type to the next at it's inception.

There is just a lot more in going from a radial to an inline engine aircraft than simply slapping another engine on, it changes the CoG, handling, you have the new cooling systems with all that plumbing, and all the many incremental changes needed for a wartime aircraft of that later era like more fuel tanks, armor, gunsights, radios, more & bigger guns etc.

It's 3 feet longer, 1,000 lbs heavier, 40 mph faster- much higher wing loading (31 vs 24 lbs / sq ft) and there is a reason they gave it a different designation. The P-36 had reached the end of it's cycle, the P-40 was the reinvention of the line.

Same with the La 5 / 5 FN / 7 / 9 ... different beast altogether from the LaGG 3

Of course in both cases the engine was the most important change - and the one that made the most difference, but it wasn't the only one.