A-1 Skyraider vs A-26

[GregP]

That's about what I thought, an analysis and not a flight test. Still looking ... but REALLY great stuff, Wayne!

Thank you!

Don't happen to know which Spitfire and which Bf 109, do you, guys? Shortround, do you? ?

Since they quote some 24 lbs. sq ft, I am assuming a Spitfire I and maybe an early Bf 109E?

Later models had considerably heavier wing loading. So, if this light, it was early models in both cases.

VERY interesting graphs! It's especially interesting to note that, at 12,000 feet, they could only stay level at about 160 mph or less, at FULL throttle, near stall! Anything faster and they were losing altitude. About what I expected ... low excess power for hard maneuvering (very prevalent near stall at high power), especially relative to what we were all brought up on in more modern jets. Wonder what speed they could make a level turn at when at, say, 25,000 feet near stall? And what g-level? I'd bet "not much." Maybe 1.7 g or so or less, shallow banks and smooth flying required!

Looks generally as if the Spitfire could pull maybe about 0.5 more g than the Bf 109, at least on those models, when flown by British pilots.

Wonder how these graphs would have looked if flown by experienced German pilots? Of course, THEY would not be really famiiliar with the Spitfire, the same as the Brits weren't very familiar with the Bf 109s. I'd bet a difference, even if slight.

I would not be surprised at a 10% delta both ways. That is, the German test could have shown the Bf 109 as about 10% better and the Spitfire as about 10% worse, just from lack of familiarity and lack of proper engine / prop tuning and maintenance. If so, they could very slightly swap positions.

Interesting. Shows them nearly equal, and I would expect the Brits to fly their own planes somewhat harder, if only from better familiarity and perhaps better condition of the aircraft. Captured planes are not usually the "cream of the crop!" and the logixitcs chain is quite long, if it exists at all.

Wonder of these were flown at more or less equivalent weights, relative to the stock normal aircraft load capabilities? Or maybe at light Spitfire and heavier German weights? I doubt there was much pressure to find the Bf 109 as "better than a Spitfire," but could easily be wrong. Perhaps not, though ...

 

[Zipper730]

A1s encountered, and shot down 2 La-7s or La-9s around Hainan island a little after the Korean war.

How did the La-7 & La-9 compare to the La-5?

I've never seen a real turn comparison between equivalent Spitfire and Bf 109 models. All I have seen is people fropm both sides making claims.

wuzak gave specific numbers it would seem

If would be good to see a test from both the German and the British side of equivalent aircraft versions!

True shit...

I'm not making a statement either way, I'm saying I don't really know, and especially don't know what would happen at lower speeds or higher angles of attack when the Bf 109 slats come open. There have been some extraordinary claims made in here about the slats, but they only amount to about 24% of the wing's span, and basically cover the ailerons, so they do NOT affect most of the airfoil. Instead they serve to keep the ailerons effective while adding a small amount of lift.

I didn't know that...

No agenda, just wishing for a well-documented test from both sides. Haven't found it yet!

Sounds logical

What it says more about is the agility of the Skyraider at light weight and low altitude, and its ability to decelerate and accelerate quickly and turn sharply with a wingtip almost in the tree tops.

How did the A-1 go from a top-speed of 375 mph to 322 so early on?

Not really a "test" but calculations by the British.

http://www.spitfireperformance.com/spit109turn.gif

and

http://www.spitfireperformance.com/spit109turn18.gif

Now if some can find the report/s or test/s that these are based on or confirmed by?

I know this will make me sound real dumb, but does a straight climb read 8-degrees, a theta, or a phi, or an infinity sign?

Report BA 1640, September 1940

Okay, so the Germans were either ballsier in their flying, or were more comfortable pushing it to the max because of the handling characteristics of the plane; for British pilots who had more cojones and were more willing to push it, they'd get inside them easy?

 

[wuzak]

Okay, so the Germans were either ballsier in their flying, or were more comfortable pushing it to the max because of the handling characteristics of the plane; for British pilots who had more cojones and were more willing to push it, they'd get inside them easy?

I would put it down to more experience. Maybe a little extra skill.

 

[wuzak]

That's about what I thought, an analysis and not a flight test. Still looking ... but REALLY great stuff, Wayne!

Thank you!

Don't happen to know which Spitfire and which Bf 109, do you, guys? Shortround, do you? ?

Since they quote some 24 lbs. sq ft, I am assuming a Spitfire I and maybe an early Bf 109E?

It is either a Spitfire I or Spitfire II vs a Bf 109E.

Evidently more than one Spitfire was used too, as the report mentions dive comparisons between the 109 and Spitfires with both a 2 pitch propeller and a constant speed unit. The Spitfire could comfortably keep with the 109 in a dive.

The turn radius charts were calculations, but evaluative tests were done with the Spitfire and 109, with both experienced RAE pilots and a few service pilots. As in the section shown previously, some of the service pilots were not comfortable tightening the turn to the Spitfire's full ability, whereas the RAE pilots were.

The main areas where the Spitfire could not compete with the 109 were negative G manoeuvres and low speed/high angle climbs.

 

[Shortround6]

Thank you

 

[Shortround6]

I would guess ( and could well be wrong) that somewhat experienced German pilots could push a bit harder using the slats as a stall warning. Being told to expect the slats to deploy before stalling is a more positive indicator than being told to expect a slight shudder or whatever the British fighters did before stall. Slats are either out or they are not out and Shudder may differ when landing at around 70mph and under 1 G and turning at 5Gs plus and the stall speed has more than doubled.

 

[drgondog]

I'll see if I can find the data from VVS tests that were here 'way back when' when Soren and Arsenal were at each other's throats. IIRC - The low level max turn rate/min 360 turn time for the Bf 109F was in the 19 sec range - and the P-40 and P-39 were in the same range with P-39 having slight edge. Level altitude turn with extrapolated CLmax in the 1.3 range for the 109.

 

[tyrodtom]

Zipper 730 you asked how the La-7 and La-9 compared to the La-5 . I think it would be reasonable to assume that each was a improvement on it's predecessor. The La-7 was about 20 mph faster than the La-5, and greater roc. The La-9 was a post war development of the La-7, again slight improvements.
I think many of us are still waiting for some details of how a A-26 out turned a Bf109 Zipper 730.
You've hinted at a documentary, and that it might have been a fire fighting conversion A-26, so that would mean post war.
But other than the people involved you've provided absolutely no other details .

 

[eagledad]

Greg

For a German view of the Spitfire's turning ability, check

Kurfürst - Vergleichsfliegen Bf 109 E, Bf 110 C, Spitfire, Hurricane und Curtiss.

Eagledad

 

[GregP]

Thanks Eagldad,

I'll read it even though pre-disposed to ignore anything from Kurfurst. I have never found him to be believable after looking in even a little depth, but also could be wrong. When I first discovered his website, I liked it. Right up until I realized that he quoted the highest number he could find for anything German and the lowest number he could find for anything not German.

If you have, say, 5 numbers from 5 tests, all at equivalent conditions, your best estimate is the square root of the sum of the squares, not the absolute highest number! If I had 4 tests and 4 numbers were low and one was high, I'd assume the high number was an outlier and ignore it, not quote it.

A good place to look about Spitfire propellers is:

Stories of the Battle of Britain 1940 – Constant-Speed Propellers — Battle of Britain | 1940 | Reference | Spitfire Mk. I

OK, I read it and had to laugh. The 2-position prop was only used at the very start of the war, leading me to think Spitfire I or Ia. All Spitfires were converted to constant-speed by 16 Aug 1940. The rest were constant speed. They didn't give any specific models or test weights, and didn't give much in the "what altitude and g-load were yopu doing?" type stuff. It is, instead, a "flight impression" of someone very familiar with the Bf 109E and not so familiar with the enemy aircraft, as one might rather obviously expect.

This was an evaluation by a combat pilot, not a comparative test, unless I just missed the charts.

Many of the British tests are in a similar vein, with no mention oif slats open or closed, no weights, and I especially interested to read that the Bf 109 out-rolled the Spitfire, Hurricane, and Curtiss (P-36 or P-40?) since the Bf 109 was widely regarded in Allied circles as a poor roller!

Of course, I have almost always read mid-to-late-war tests, not BOB-timeframe tests. Back then, perhaps the Bf 109 DID roll better. I am under the distinct impression that the early BF 109E was a slightly better fighter than the early Spitfire, and the conversion to constant-speed props was one attempt to "close the gap." Seems that when they DID close the gap, the Germans also made imcremental improvements and the two swapped back and forth throughout the war as to which was a bit superior at any time.

It is this very swapping back and forth that make me a bit skeptical of claims that the Spitfire was vastly superior, or vice-versa. They were like the later MiG-15 and F-86, pretty close! One could be said to be better somewhere in the flight envelope, but not everywhere. Also, both were and ARE much easier to takeoff and land when on grass than when on pavement. The Spitfire is somewhat squirrely on pavement, particularly in a crosswind, but the Bf 109 is positively vicious on pavement! Maybe it would have been fine on wet steel-mat runway! Like the stuff we used in Korea later.

 

[FLYBOYJ]

Kurfurst is a former member, although very knowledgeable with regards to the -109, he became unhinged when anyone presented any formidable data that contradicted anything from his website or archives.

Nuff said, carry on!

 

[Zipper730]

I would put it down to more experience. Maybe a little extra skill.

That makes sense. The reason the Germans would have had more confidence was experience: When I know what I'm doing, I tend to be more confident as a general rule.

I would guess ( and could well be wrong) that somewhat experienced German pilots could push a bit harder using the slats as a stall warning. Being told to expect the slats to deploy before stalling is a more positive indicator than being told to expect a slight shudder or whatever the British fighters did before stall.

Good observation!

Zipper 730 you asked how the La-7 and La-9 compared to the La-5 . I think it would be reasonable to assume that each was a improvement on it's predecessor.

I was thinking of turn-rates in specific, and faster planes can turn slower.

I think many of us are still waiting for some details of how a A-26 out turned a Bf109

I'm mostly in need of the g-load data

You've hinted at a documentary, and that it might have been a fire fighting conversion A-26, so that would mean post war.

The pilot who flew them was a fire-fighting pilot; Moga's narration said it could get inside an Me-109 -- implying WWII.

It has to be noted that a turning-circle isn't necessarily something that will always be useful: Roll rate too slow, not enough power to hold the turn. It's possible that it was just an interesting trivial bit.

 

[wuzak]

Greg, the RAE report list st the weight of the 109 during tests as 5,580lb and the Spitfire 6,000lb.

 

[Elvis]

The aircraft minimum turn radius depends only on the square of the velocity divided by 1 over (g * tan [bank angle]). Naturally, the square of the velocity dominates. If they had to maintain a standard speed, then it is almost impossible for the Buffalo to have done the turn in 7 seconds when a Bf 109 took 25 - 27 seconds.

There is no way a Bf 109 could only turn 7.2° per second while a Buffalo moving at the same speed could make 25.7° per second! The power to weight ratio of the Bf 109 was one of the better ones on the Altantic side of the war. It certainly could climb away from most of the opposition.

25.7° per second may not be possible in a WWII fighter. I might believe a turn time of some 12 - 15 seconds is possible, but the Bf 109 was a strong, capable airplane, and was a considerably better fighter than any Buffalo! I hope someone manages to find that study because I suspect you may disremember a time or two in there, Elvis.

I certainly have made a couple of memory errors in here, and it's not intended as an insult or anything like that. It's more of a "I'd love to see that study" type of thing, and make sure it wasn't released during Kruschev's time as Premier Minister in the 1960s. That was a large portion of history was re-written to suit the Party ... and they may have just been afraid of the Finns flying Buffalos, and needed an excuse to avoid being an unfortunate part of a purge.

Cheers.

But if I can turn inside of you, GregP, then I'd be travelling a lesser distance.
Shorter distance takes less time to cover at the same speed, compared to a longer distance.
I'll see if I can dig up that thread.


Elvis

 

[GregP]

Hi Joe,

No more on it from me.

I'd still love to see comparative testing of the two planes from the point of view of both sides, though. Until I do, I still think of them as more or less equal under most conditions, with some conditions favoring one or the other.

The Germans didn't roll right over the British and the British (and later Allies) didn't exactly have a cake walk, either. You can't have a great mistatch for six years of total war! The only way that happens is if there is some give and take on both sides, with one side eventually getting the upper hand, by way of skill, technology, better leadership, luck, or a combination of all of the above.

It probably didn't help the Germans that the British broke their codes early on, either. Both sides still had victories and losses.

Though I look at WWII with interest, particularly in aviation, it's not something I wish I had been there for.

 

[GregP]

Hi Elvis,

If you hold the speed constant, then the plane with the better coefficient of lift will turn tightest, assuming the airframe is strong enough for it and it has sufficient power available for a level turn.

If you hold the g-force constant, the plane with the better coefficient of lift will turn the slowest, assuming the airframe stays together and it has enough excess power to continue.

Once you get to the airframe limit, the g-force and speed are both constant in a level turn. Usually one plane or the other will be able to turn slightly tighter than the other one. Though exactly-matched planes are rare, they are close since both designers were trying very hard to make optimum design choices. The question whould be, exactly what was optimized?

The above assumes the total wing area will generate sufficient lift to sustain the g-load of interest at the current weight. Once weight exceeds lift available, you are stalled.

If you hold the speed and g-force constant, their turns should match. As we all know, a "standard rate" turn is 3° per second, and it results in a 2-minute 360° turn or a 1-minute 180° turn. If a standard-rate turn is done at, say, 250 knots all the way, the turn track will be the same for any aircraft, regardless of whether it is a fighter or a Boeing 747. Things such as slats or "maneuvering flaps" were attempts to momentarily generate a better corefficicent of lift, to make a tighter turn possible for some period of time or through some particular speed range.

But I'm sure you know all that, Elvis. Most people in here do, and some could write a textbook on it. Drgondog is one of those, as we both know.

The Spitfire had a wing that was complicated to build, but I would still love to have seen what slats similar to the Bf 109 slats might have done for it in a turning fight! Perhaps it wouldn't have helped because they had washout doing the same job. But, add BOTH and it might have helped more. To the Air Minstry, it might not have been worth the price to have it added on, but I bet a fighter pilot would have voted the other way, assuming it helped. Unfortunately, the accountants won most of those fights.

 

[Shortround6]

When comparing the roll rate or roll response of early and late war 109s you have several things to consider.
1. is the change in wing tip shape. The "E"s having a square wingtip with very little wing going beyond the end of the aileron. The "F"s and later had the round wingtips with 655/6 mm of wing tip beyond the aileron. Spitfires with "clipped" tips rolled better.
I don't know if there was a change in aileron shape/dimensions between the early and late 109s. There was a change in the gap or seal?

2. A common complaint with almost all of these aircraft is that the ailerons stiffened up with speed. If you have a 109E with a top speed (best altitude) of around 350mph and in combat often going a bit slower it will have different aileron response/roll rate than a 109 with a top speed of 380-400mph as in many equivalent situations the later plane will be going faster (even if not at top speed) and be dealing with the slowed down or heavier aileron response.

As an example the FW 190 was supposed to roll at 135 degress a second at 290mph IAS (at 10,000ft and 50lbs stick pressure) while increasing speed to 330mph IAS lowered the roll rate to 108 degrees per second.

I don't know if these factors come into play but they help explain the difference in perceived roll rate at different times. AS can the opposition. If you are flying against early Spitfires then out rolling them may not be that hard. A few years later with a higher percentage of clip wing Spitfires and and P-47s and P-51s which all out roll early Spitfires at high speeds and a 109 even with the same roll response as an early one could find itself at a disadvantage.
http://www.wwiiaircraftperformance.org/naca868-rollchart.jpg

 

[GregP]

Yeah Shortround, I agree.

WW2aircraftperformance has some charts in it, but the charts don't say which models of the fighters were used to generate them or even the timeframe of the data. Also, the roll comparison charts show a drawing of a fighter rolling, say, 90° for one plane and the same pic rolled, say, 60°, for another plane. That maybe gives you a comparison at some speed, but not a time to roll or a roll rate in ° per second.

Seems like getting quality data is so rare that it looks like nobody wanted you to be able to piece it together from one document. which is likely the exact case. They probably did that like the tech orders, so you needed a complete set to get the whole picture.

The thing is, using a calculated expected response isn't the same as a flight test, and a flight test isn't the same as another flight test conducted by a pilot really familiar with the aircraft, particularly in actual combat. My guess is the combat pilot would probably use more force and pull a bit harder than a test pilot with no combat experience. But ... that's a guess.

Generally, the combat pilot might not care about the ease of flying formation in a plane since they are usually in rather loose formation in a combat zone. Rigid, tight formations are shot down easily because nobody is paying attention to anything except staying in formation position! And in combat, the guy who sees the enemy first is MUCH more likely to come out on top. So a combat pilot and a non-combat test pilot might like entirely different flying qualities and pay attention to entirely diffrent things when doing a flight evaluation.

I've read where some pilot liked, say, the P-39 (when down low) and others thought it was a dog. Both cannot be the case simultaneously. Probably one was paying attention to the P-39 when it was in its element down low and the other was evaluating it when it was at the altitude where he thought he needed to fly.

I'd think you would need to know your enemy, because the flight characteristics of your plane when at the best speed and altitude of your enemy were where you were most likely to encounter him if he had anything to say about it.

Just rambling, so I'll shut up now ...

 

[Zipper730]

Greg, the RAE report list st the weight of the 109 during tests as 5,580lb and the Spitfire 6,000lb.

These were normal loads right?

Seems like getting quality data is so rare that it looks like nobody wanted you to be able to piece it together from one document. which is likely the exact case. They probably did that like the tech orders, so you needed a complete set to get the whole picture.

It would have made espionage hard to do. Of course, in 2017, this is just pure curiosity.

 

[wuzak]

These were normal loads right?

About that.