Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Galand on October 10, 2005, 10:50:54 PM
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So basically the G-6 is the same with a caged cockpit
The G-14 is a G-6 with better WEP
and the K-4 is just the G10?
So what's new exactly?
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Originally posted by Galand
So what's new exactly?
Spitfires
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The G14 will have a faster top speed, thus we will have an in-between between the G6 (a 1943 plane) and the K-4 (a 1945 plane). There is currently a HUGE performance gap between these two planes, and the G14 will bridge the gap.
I'm personally hoping for an E-7 as well, but that's a pipe dream :P
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Sux for the people who flew the G10 with gondolas
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The K4 will still have gondies. The hub will be 30mm is all.
Oddly enough, I've found it's MUCH easier to land 30mm hits if you have the gondies (mixed 20mm and 30mm). It might just be in my head but it's odd, I seem to land them far more. Same with the 190A8's mixed bag, they land far more often than a single 30mm in the 109 or ta152.
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o crap
109K's overall performance will drop when armed with GONDOLAS. The drag of wing guns will be counted too:eek:
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I think it already is.
The deal with the 190a5 was that the pylon wasn't counted towards drag, even after the centerline ord was dropped. I think on the 109s that the gondies have always been counted. No change, is my guess.
EDIT: I wonder if they'll get a little drag (-1 mph or so??) for the centerline DT/bomb mount. In real life it was a rounded shape so it probably has little drag, but it was a "bump" the air had to flow over.
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Originally posted by 1K3
o crap
109K's overall performance will drop when armed with GONDOLAS. The drag of wing guns will be counted too:eek:
That is already counted on the Bf109G-10. No change.
I am looking forward to trying the Bf109G-14 out. It is definately new.
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Originally posted by Krusty
EDIT: I wonder if they'll get a little drag (-1 mph or so??) for the centerline DT/bomb mount. In real life it was a rounded shape so it probably has little drag, but it was a "bump" the air had to flow over.
Indeed, 109 drag docs I have say the Schloss 503 DT/bomb rack on the 109 came with only -4 kph (2,5mph) speed loss at SL. Gondies werent that bad either, -8 kph or about -5mph for SL. The speed loss is about 50% greater at best altitude. but because of the gondola weight ROC was down by ca -2m/sec - still an excellent climber though.
I suppose the gondies will be an option for them, not a permanent feature - that would be odd, since gondies were filed kits, no more permanent than bombs or racks for DT. They could be installed or removed, and in fact pretty rarely used after escorts appeared.
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I only load the gondola's with buff-hunting, so -5mph won't be that bad
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I truly hope they would build the G-6 with a caged cockpit, but WITH Galland head armor!
That would add variation and separate G-6 better from G-2 and from G-14. Sacrificing the better climb and speed of G-2 to heavier machineguns and better rear view of the G-6 would make a nice option and trade-off.
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Originally posted by Kurfürst
Gondies werent that bad either, -8 kph or about -5mph for SL. The speed loss is about 50% greater at best altitude.
[/B]
Only -5 mph seems rather generous considering the P-51B lost 8 mph at sea level for its wing racks. The Mustang's wing racks were much, much smaller than the 109's gondolas.
Hmm...
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It is not necessarily the size, but the cross-section etc. causing drag and affecting the aerodynamics. You could not argue that a bigger wing should be slower than a smaller one, could you?
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Originally posted by BlauK
It is not necessarily the size, but the cross-section etc. causing drag and affecting the aerodynamics. You could not argue that a bigger wing should be slower than a smaller one, could you?
The Mustang's racks were aerodynamically faired and much smaller in frontal area, as well. There was no cannon barrel protruding forward, either. It seems very unlikely that the kannonen boot installation was less draggy than the Mustang's wing racks. Quite the opposite in fact, although I could be wrong.
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Originally posted by LRRP22
The Mustang's racks were aerodynamically faired and much smaller in frontal area, as well. There was no cannon barrel protruding forward, either. It seems very unlikely that the kannonen boot installation was less draggy than the Mustang's wing racks. Quite the opposite in fact, although I could be wrong.
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Mustang's racks are Mustang's racks, and 109's gondolas are 109's gondolas ...
The speed loss was measured consistently to be 9-12 km/h (at 0 m and ~500 km/h).
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Originally posted by Porta
Mustang's racks are Mustang's racks, and 109's gondolas are 109's gondolas ...
The speed loss was measured consistently to be 9-12 km/h (at 0 m and ~500 km/h).
Ah, that's probably the reason- 9 kph at 500kph for the 109, while the Mustang's 12 kph loss at SL was measured between 600 (USAAF) and 640 (RAF) kph.
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Well DUH the P51s bomb racks are going to make more drag. They're BOMB racks, with shackles and mounting slots and all that fun stuff, none of which (I might add) is conducive to aerodynamic flow.
Gun pods, on the other hand, only have the ejection chute (and the barrel of the gun itself is probably negligable drag).
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Originally posted by Krusty
Well DUH the P51s bomb racks are going to make more drag. They're BOMB racks, with shackles and mounting slots and all that fun stuff, none of which (I might add) is conducive to aerodynamic flow.
Gun pods, on the other hand, only have the ejection chute (and the barrel of the gun itself is probably negligable drag).
Have you ever actually looked at a P-51's wing racks?
(http://www.swissmustangs.ch/mediac/400_0/media/DIR_34770/P-51D~5.jpg)
Not exactly the draggiest appendage imaginable, is it?
(http://www.luchtoorlog.be/Images/me109g/g620.jpg)
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Not exactly the draggiest appendage imaginable, is it?
It looks like a typical WWII wingmounted rack. Absolutely nothing special.
Reminds me of larger version of the ETC 50 rack.
The deal with the 190a5 was that the pylon wasn't counted towards drag, even after the centerline ord was dropped. I think on the 109s that the gondies have always been counted. No change, is my guess.
Is the ETC 501 rack always mounted on the FW190 in AH? It should not be as it was removed and replaced as mission required.
The Flugzeug-handbuch specifies it will be removed if not in use.
Having no experience and no manual it took a couple of guys about 4 hours to remove our ETC rack. However an experienced crew of 4 could do it in about 15 minutes. Surprisingly it is one of the more involved FW190 maintenance tasks.
All the best,
Crumpp
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Crumpp, the rack is not there if nothing is loaded.
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Thanks.
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Originally posted by Crumpp
It looks like a typical WWII wingmounted rack. Absolutely nothing special.
Reminds me of larger version of the ETC 50 rack.
Crumpp
I didn't say it was anything special, Crumpp. I just said it was smaller and less draggy than the MG151 gondola. It is. Krusty seemed to think the opposite was true.
I'm not sure if it is any larger than the ETC 50. Could the ETC 50 carry a 1,000 lbs bomb?
LRRP
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No,
It was limited to 50Kg bombs.
All the best,
Crumpp
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Originally posted by Crumpp
No,
It was limited to 50Kg bombs.
All the best,
Crumpp
Wow! 3 minutes- that was quick...;)
LRRP
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Originally posted by LRRP22
Have you ever actually looked at a P-51's wing racks?
(http://www.swissmustangs.ch/mediac/400_0/media/DIR_34770/P-51D~5.jpg)
Not exactly the draggiest appendage imaginable, is it?
(http://www.luchtoorlog.be/Images/me109g/g620.jpg)
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You can argue as long as you want, LRRP2. For you, the Mustang is always better, in everything. You always argue about that.
Now the facts are, regardless of how you debate them or what picture you post, is that the documented speed loss noted for the Bf 109 gunpods is 5 mph at SL, for the Mustang wing racks it`s 8mph. Sorry, that's what the docs say, it was not me or other who made it up, so try to live with it.
If we consider the loss of speed with other bombracks, ie. the (single) ETC 500 is stated to chop off 8 mph at SL on the Bf 109, and the (single) ETC 501 is said to chop off 10 mph of the FW 190 SL speed. In fact when the Russians tested a G-2 with and without gondies, they found the top speed at altitude to be 649 vs 666 kph, ie. 17 kph or 10mph difference.
Considering the Mustang carried two bombracks under the wings, 8 mph at SL, and 12 mph at altitude or 20 km/h.
And frankly, this is what I'd expcept. Regardless how you boast on how 'ultra clean' it was, there was nothing special about it. It looks like any other bombrack - even the picture you posted shows nicely what makes up for the drag, it's mounted on the middle of the wing, not near the leading edge hence when the airflow hits the rack it will cause more turbulance; the lines are quite abrupt, no smooth transition again - have you ever wondered why aircraft designers are so fond of teardrop etc. shaped surfaces instead of 'box planes'? And look at the bomb shackles, there are 4 of them as I can see, and they are quite big. Drag is not related to area, (ie. the wing size analogy), but the smoothness of transition. Even the IFF aerial was counted with 2mph speed loss as far as I can remember. It isn't about 'looks'.
Point is, the Mustang D's max speed is usually given without bombracks in most sources, ie. 703 kph at altitude, and it wasn't representative of the RL - if in good contition! - aircrafts performance since it almost without an exception it always carried bombracks for DTs on escort missions; in fact the aircraft's top speed was around 670-680 kph with those racks at altitude. It was discussed a while ago, even you agreed with it.
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Originally posted by LRRP22
Ah, that's probably the reason- 9 kph at 500kph for the 109, while the Mustang's 12 kph loss at SL was measured between 600 (USAAF) and 640 (RAF) kph..
Which 109 would only do 500kph....? Even the 109F was faster than that, Gs usually topped out at 530-580 kph at SL.
Problem is, even late versions of the 109s like the 109K, which could easily do 607 kph, the gondies make only ~10kph difference.
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In AH, the speed loss due to gondolas is 9-10mph at SL:
109G-6: 329/338 mph
109G-10: 359/369 mph
The wing racks of P-51 are always included, even if DT's or ord is not chosen (368mph)
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Originally posted by Kurfürst
Which 109 would only do 500kph....? Even the 109F was faster than that, Gs usually topped out at 530-580 kph at SL.
Problem is, even late versions of the 109s like the 109K, which could easily do 607 kph, the gondies make only ~10kph difference.
Proof positive of Barbi's lack of reading comprehension.
Barbi he did not say the top speed was 500kph but at 500kph the gondolas caused a loss of speed of 9kph. He then goes on and says the P-51s loss of speed was measured at 600kph(USAAF) and 640kph(RAF). Ie. at a higher speed where the speed loss should be greater. So do you have the P-51 speed loss at 500kph?
Since you mentioned 190s, the ETC503 caused a loss of speed of 18kph(11mph)/SL. The MK103 gondolas caused a speed loss of 27kph(16.8mph)/SL and 35kph(21.7mph) /20kft.
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Sigh. I realize that the Mustang was far from "better, in everything", if only you could make the same realization with regards to the 109. Apparently, you believe the 109 was so good that it was somehow immune to the fact that drag increases to the square of any speed increase. After all, that's the only thing that could explain no increase in drag penalty at both 500 kph and 600+ kph.
One thing should be fairly obvious- if you removed the MG151 gondolas from a given 109 and, for whatever reason, replaced them with Mustang wing racks- that 109 would be faster. Likewise, the P-51 would be slower with gondolas than it would be with racks.
As for the 109K "easily" reaching 607 kph, don't you mean it was estimated to reach 607 kph under ideal conditions, but only at a power setting that was, at best, rare?
Originally posted by Kurfürst
You can argue as long as you want, LRRP2. For you, the Mustang is always better, in everything. You always argue about that.
Now the facts are, regardless of how you debate them or what picture you post, is that the documented speed loss noted for the Bf 109 gunpods is 5 mph at SL, for the Mustang wing racks it`s 8mph. Sorry, that's what the docs say, it was not me or other who made it up, so try to live with it.
If we consider the loss of speed with other bombracks, ie. the (single) ETC 500 is stated to chop off 8 mph at SL on the Bf 109, and the (single) ETC 501 is said to chop off 10 mph of the FW 190 SL speed. In fact when the Russians tested a G-2 with and without gondies, they found the top speed at altitude to be 649 vs 666 kph, ie. 17 kph or 10mph difference.
Considering the Mustang carried two bombracks under the wings, 8 mph at SL, and 12 mph at altitude or 20 km/h.
And frankly, this is what I'd expcept. Regardless how you boast on how 'ultra clean' it was, there was nothing special about it. It looks like any other bombrack - even the picture you posted shows nicely what makes up for the drag, it's mounted on the middle of the wing, not near the leading edge hence when the airflow hits the rack it will cause more turbulance; the lines are quite abrupt, no smooth transition again - have you ever wondered why aircraft designers are so fond of teardrop etc. shaped surfaces instead of 'box planes'? And look at the bomb shackles, there are 4 of them as I can see, and they are quite big. Drag is not related to area, (ie. the wing size analogy), but the smoothness of transition. Even the IFF aerial was counted with 2mph speed loss as far as I can remember. It isn't about 'looks'.
Point is, the Mustang D's max speed is usually given without bombracks in most sources, ie. 703 kph at altitude, and it wasn't representative of the RL - if in good contition! - aircrafts performance since it almost without an exception it always carried bombracks for DTs on escort missions; in fact the aircraft's top speed was around 670-680 kph with those racks at altitude. It was discussed a while ago, even you agreed with it.
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Originally posted by Kurf�rst
And frankly, this is what I'd expcept. Regardless how you boast on how 'ultra clean' it was, there was nothing special about it. It looks like any other bombrack [/B]
Don't you think that maybe most bomb racks looked the same for a reason? Don't you think they would look more like gondolas, if the gondola shape was more efficient?
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I think they just tried to make the fairing as small as possible, without concerning too much about the aerodynamic loss
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Originally posted by frank3
I think they just tried to make the fairing as small as possible, without concerning too much about the aerodynamic loss
I'm sure they were designed to be as efficient as possible for the loads they were designed to carry. You can bet that if a different, but bigger, shape was more efficient, then they would have been bigger.
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Not so. They knew that faired DTs were better aerodynamically, but the only plane that ever got them was the Mossie. Just because they DO something doesn't mean that they take into consideration every aspect. The plane flew pretty fast enough, they didn't give a crap if it lost 10mph because of bomb racks. The bomb racks were necessary.
In general, aerodynamics were still in the fledgling stages in WW2. Hell it took the RAF til 1945/46 to figure that giving the spitfire WHEEL DOORS would add 5mph. Something as simple as a spit climbing with closed radiators (rigged closed) gave it an additional 500+ fpm climb rate. Drag is a subtle thing. Why argue why a pony has "this" drag and a 109 has "that" drag. They just *did*. Fact. End of matter. Nobody knew any better.
I'd personally argue that it wasn't until the speed race after the war that people really sat down and started thinking about what slows a plane down in flight.
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They knew perfectly well what caused drag.
Look at the world air speed record holders in the 1930s, the Schneider Air Races, and all the rest. The Germans, British, French, Italians, Americans all pioneered very sleek drag free designs that went very fast in the inter war years.
It was the 1940s, not the 1490s.
"Hell it took the RAF til 1945/46 to figure that giving the spitfire WHEEL DOORS would add 5mph."
-The Spit VII, VIII, XII and XIV all had wheel doors, the 109G-6, 109G-14, and 109G-10 did not. Fixed tail wheels were simply a design decision for combat a/c in WW2, some felt that the retractable tail wheel was just something else that could fail upon landing (which they sometimes did), and cause damage to the a/c. It wasnt considered that big a deal.
They did care about a loss of 5-10 mph, but as you say, bomb racks were required, as were DT racks, just as gondolas were, and they were used. They were combat a/c and drawbacks like that were just the cost of doing business. You cant fighter-bomb without racks to carry them.
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He meant doors to cover the outer half of the mainwheels.
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Oh those, well, same thing, they were an extravegance that were not considered crucial, and it had nothng to do with not knowing about drag in WW2, thats for sure. 109K-4 and Spit Mk.21 were the only varients of those two to have them (they also both had retractable tail wheel).
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It was only after tests that spanned the entire war that they came out with a report on what caused drag (and how much). They did not know about the wheel doors before then. They might have thought it was negligable or not important (seeing that the fighters flew, flew well, and got kills, etc, what does it matter if they have doors?).
Also, what won speed races was power to weight and wing shape. Messerschmitt designs had one thing, a really strong (for the time) engine, a thin, modern, wing, and a lightweight frame. They were ungainly as hell and boxy. Not very aerodynamic, either.
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On the topic of aerodynamics, anyone ever wonder if induced drag reducing winglets (like those on a 777) would have improved the manuverability of WWII fighter?
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There was a lot of effort by all combatants to reduce drag. They all knew about it and they all fought to minimize it. Look at the cowling on the A6M and Fw190. Those are both designed to reduce the drag of a radial engine. The thin wings on the Spitfire are a direct legacy of Mitchell's experience designing aircraft for the Sneider Trophy races. The compact form of the Bf109 is to minimize drag. The P-51 was designed from the start to have less drag than contemporary fighters. The Mosquito's whole shape is likewise to minimize drag as was the Ki-46's. The only real change from the La-5FN to the La-7 is to reduce drag.
In all these cases they did their best within the limitations that were imposed on the design team. Sometimes those limitations were due to the mission of the aircraft, sometimes due to budgetary requirements and sometimes they had to sacrifice to keep it simple enough to build and operate effectively.
Aerodynamics were not a new concept.
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"On the topic of aerodynamics, anyone ever wonder if induced drag reducing winglets (like those on a 777) would have improved the manuverability of WWII fighter?"
Why would they improve maneuverability?
They are there to reduce drag.
-C+
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Specificly they reduce induced drag by limiting the creation of wingtip vorticies.
So, to be more specific improve manuverability in a low speed turning contest.
Reduced drag, I was thinking, would mean more excess thrust or more lift, potentialy including the horizonal component of lift which makes a 'plane turn.
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...so does the above make sense or nonsense?
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Well, racks or no racks, the P51 is very fast for its weight and HP's.
Similar power to what - the 109G-6? Heavier, but yet faster?
Anyway, I'm eager to see and try the G-14, - could be my next pet in AH :D
Wonder what skin it's gonna get. I vote for Hartmann's!!!!!
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Debonair, I would say that the way you described them especially in slow speed their effect is very small if it exists at all.
They do help the contemporary airliners to save fuel at their normal cruising speeds by reducing the wingtip vortices and their effect on drag.
-C+
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on the P51 vs 109 topic, you guys were talking about the P51B drag with the racks, but a P51D pic was posted...(quite obvious with the 3 guns on the wing).
If I remember well the P51D had redesigned zero drag racks while the B model had what was available at the time, so I think you can't compare using that picture. Plus as someone said, you can't compare aerodynamics just by the looks, else we won't need drag tests. (can't remember the actual name)
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See Rule #4
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Originally posted by Angus
Well, racks or no racks, the P51 is very fast for its weight and HP's.
Similar power to what - the 109G-6?
They don't have similiar power, though the Mustang's power varied between the variants, even lower powered ones had at least +200HP advantage. Ie. the P-51D had 1690 HP at SL, the 109G-6 had 1455 HP.
The 109G-2's drag was equalalent to a 0.369 m2 flat plate, for example. G-6 was somewhat higher, I could give it but the doc is not with me.
From what I have seen, the P-51D and 109K had very similiar total drag, reaching very similiar powers on similiar powers, at least near ground level.
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Originally posted by LRRP22
Don't you think that maybe most bomb racks looked the same for a reason? Don't you think they would look more like gondolas, if the gondola shape was more efficient?.
They did't care, as noted. You are basically arguing that a box shaped bombrack is more aerodynamic than a nicely curved and smoothened gondola. Silly in itself, it's like box-shaped cars are more aerodynamic than teardrop shaped ones.
The built-in rack of the 109, Schloss 503 already mentioned, which was capable of carrying 1100 lbs bombload or a droptank, had a nice curved surface and no protusions, like gondolas. And it came with only -4kph speed loss.
A nice fairing can do wonders, btw. The 300lit droptank when mounted came with something like 40-50kph speedloss. However, with a small fairing placed between the DT and the Schloss 503 rack, it was reduced to 1/3 of that...
Aerodynamics is all about shape, not about frontal area.
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Originally posted by Kurfürst
They did't care, as noted. You are basically arguing that a box shaped bombrack is more aerodynamic than a nicely curved and smoothened gondola. Silly in itself, it's like box-shaped cars are more aerodynamic than teardrop shaped ones.
The built-in rack of the 109, Schloss 503 already mentioned, which was capable of carrying 1100 lbs bombload or a droptank, had a nice curved surface and no protusions, like gondolas. And it came with only -4kph speed loss.
A nice fairing can do wonders, btw. The 300lit droptank when mounted came with something like 40-50kph speedloss. However, with a small fairing placed between the DT and the Schloss 503 rack, it was reduced to 1/3 of that...
Aerodynamics is all about shape, not about frontal area.
They didn't care? A patently ridiculous claim.
The Mustangs wing racks were "box shaped"? Another ridiculous claim.
And gondolas did have protursions- a nice, long cannon barrel and a proturding ejection port.
Tell us again how the 109K's nose was cleaner than the Mustangs...
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No protrusions Kurfy?
As can be seen in the photo the rack certainly did have protrusions.
http://cipres.cec.uchile.cl/~bebustos/jpg/me109g6s.jpg
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From Kurfurst:
"From what I have seen, the P-51D and 109K had very similiar total drag, reaching very similiar powers on similiar powers, at least near ground level."
The 109K peaked at some 2000 hp right, and had lots of power at S.L.
So, the P51D peaks with 1690 hp.
Or do you refer to the less boosted 109K????
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See Rule #4
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Originally posted by Noir
on the P51 vs 109 topic, you guys were talking about the P51B drag with the racks, but a P51D pic was posted...(quite obvious with the 3 guns on the wing).
If I remember well the P51D had redesigned zero drag racks while the B model had what was available at the time, so I think you can't compare using that picture. Plus as someone said, you can't compare aerodynamics just by the looks, else we won't need drag tests. (can't remember the actual name)
That's true. I would expect the D's racks to incur slightly less drag penalty than the B/C's. How much, I don't know. None of the testing establishments differentiated between the two. Both the USAAF and RAF attributed a 12 mph loss to both types at max speed.
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See Rule #4
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Originally posted by Angus
From Kurfurst:
"From what I have seen, the P-51D and 109K had very similiar total drag, reaching very similiar powers on similiar powers, at least near ground level."
The 109K peaked at some 2000 hp right, and had lots of power at S.L.
So, the P51D peaks with 1690 hp.
Or do you refer to the less boosted 109K????
Be careful Angus with that 2000 HP. Lrrp2 always accuses me of 'cheating' when I am lazy and write HP instead of PS. There were about 1% difference between the two, but still... ;)
Now what I had in mind is the +25 lbs (1960 BHP at SL) Mustang D with wingracks (379 mph at SL), and what 'Leistungen 8-109 K4' noted as SL speed of the 2000 PS (about the same power if we note PS/HP difference), 377 mph. You see it's very similar, though w/o the bombracks the Mustang would be faster. OTOH, the Mustang was tested w/o paint either, that's quite a bit of drag and weight - if you recall those stripped Ju86 intercepting modded Spits - so on equal footing, no paint/no bombrack, it's the same again.
With 1690 HP, and the usual wingracks, the Mustang IV was credited with 354 mph top SL speed, but there's hardly any comparably powered 109s...
the uglier G-14s were good for 568kph/352 mph at 1800 PS, whereas the low-boosted 109K would do 370mph with 1850 PS.
BTW if you are interested in that Mustang IV tests, I can happily send over the original, though I think it's also found on MW's site :
2. Condition of aircraft relevant to tests.
2.1 General. Photographs of the aircraft are attached to the present part of the report.
The following were the chief external features:-
Six .5" machine guns in the wings, ports and ejection chutes sealed with fabric.
Camera gun port in port wing, sealed with fabric.
Multi ejector exhaust manifolds with shroud-plates.
Air intake in nose with internal ice-guard.
Aerial mast without external aerials.
Bead sight in front of windscreen.
Air filter intake in lower left cowling.
Faired bomb racks under the wings.
The aircraft was not painted. The under surface of the wings back to the main spar and the whole of the top surface had been coated with a smooth composition, the joints being filled and the remainder being bare metal. The fuselage was left with the bare metal except for a matt anti-glare finish on the top engine cowling. All other parts of the aircraft were also bare metal, except the elevator and rudder which were fabric-covered and doped.
In order to obtain adequate cooling, level speeds were done with the radiator duct flap set to a gap of 8½ inches, as coolant temperatures were excessively high with the normal setting of 7¼" gap.
2.3 Loading. The tests were made at a take-off weight of 9480 lb. with the C. of G. at 100.2 ins. aft of the reference axis. This corresponded to a typical loading with no fuel in the auxiliary fuselage tank and no external tanks or bombs.
http://www.spitfireperformance.com/mustang/tk589.html
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BTW it's interesting to compare the P-51D TK 589 flight data (with wingracks) with the 'official
Let's recall that TK 589 did 354mph at SL at 67", and removing the wing racks would give an extra 12mph :
North American Aviation, Inc.
Inglewood, California
Report No. NA-46-130
2-6-46
Performance Calculations for Model P-51D Airplane
(N.A.A. Model No. NA-122)
These calculations were prepared in connection with a comparison of the P-51D and P-51H airplane. Considerable effort was expended to achieve agreement between flight tests and calculated results, and the data as presented represent good agreement with most of the flight test results.
Calculated Altitude Performance
Fighter condition - No external load
67" HG M.P. - 3000 R.P.M.
9,611 LB
Maximum Speed
Standard Altitude Feet True Airspeed - M.P.H.
Sea Level 368
368 - 12 = 356...
TK 589 did 354mph....
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See Rule #4
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See Rule #4, #5
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Whatever, Isegrim. Rant all you want. The fact is you're comparing a well-used Mustang IV hand-me-down to a theoretical 109K-4.
If the K-4 numbers are actually test data- then post them. Period.
Mustang III sqns at +25 boost during summer of 44: 129, 306, 315, 316. New evidence seems to indicate they never stopped using it. That's all I'll say for now.
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TK 589 was 2 mph faster than your beloved 1.98 ata K-4's 'good production' estimated sea level speed of 377 mph.
Does anybody else see the humor in arguing over 2 mph?
Why does every thread in this forum degenerate into "my plane is better than your plane"?
Everyone here does know that manufacturers had tolerances specifications. They would only guaranteed performance within a percentage variation. 1 percent variation was considered good and well within tolerance. 2 mph is barely a 1/2 a percentage point from 377mph. Those tolerances were pretty broad even at 1 percent. The FW190 had a 15kph margin between the best and worst tested data. All was within the 1 % manufacturers guaranteed performance.
Can we get this back on track instead of watching the same old tired players acting on the stage again pushing private agendas?
All the best,
Crumpp
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Oh, so now 8 mph at seal level has become 12 mph, huh?
368 - 8 = 360. That's 4 mph slower than 43-24777's SL speed.
Then again, AHT says the USAAF reached 373 at SL.
373 - 8 = 365. That's 1 mph faster than 43-24777's SL speed with racks.
Despite what you like to claim, NAA and the USAAF rated the P-51D within 1-2 mph of the P-51B-15-NA at all altitudes, i.e. 439 mph vs 437 mph. Of course, NA-46-130 rates the P-51D at 440 mph clean as opposed to the 437 mph usually listed. You left that out, though.
Like I've told you repeatedly, I don't have a problem with TK 589's speeds. Just take them for what they are: speeds attained by a veteran example, not a factory fresh example. Still, even used, TK589 was faster was faster than the 1.98 ata K-4 at sea level on virtually identical power. Not bad for a veteran airframe vs calculated data, huh?
Again, lets see that 109K-4 Test data....
Originally posted by Kurf�rst
BTW it's interesting to compare the P-51D TK 589 flight data (with wingracks) with the 'official
Let's recall that TK 589 did 354mph at SL at 67", and removing the wing racks would give an extra 12mph :
North American Aviation, Inc.
Inglewood, California
Report No. NA-46-130
2-6-46
Performance Calculations for Model P-51D Airplane
(N.A.A. Model No. NA-122)
These calculations were prepared in connection with a comparison of the P-51D and P-51H airplane. Considerable effort was expended to achieve agreement between flight tests and calculated results, and the data as presented represent good agreement with most of the flight test results.
Calculated Altitude Performance
Fighter condition - No external load
67" HG M.P. - 3000 R.P.M.
9,611 LB
Maximum Speed
Standard Altitude Feet True Airspeed - M.P.H.
Sea Level 368
368 - 12 = 356...
TK 589 did 354mph....
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It's not about 2 mph, Crumpp. It's about Isegrim constantly making spurious comparisons and misrepresentations. I know you've butted heads with him repeatedly over the very same issues...
Originally posted by Crumpp
Does anybody else see the humor in arguing over 2 mph?
Why does every thread in this forum degenerate into "my plane is better than your plane"?
Everyone here does know that manufacturers had tolerances specifications. They would only guaranteed performance within a percentage variation. 1 percent variation was considered good and well within tolerance. 2 mph is barely a 1/2 a percentage point from 377mph. Those tolerances were pretty broad even at 1 percent. The FW190 had a 15kph margin between the best and worst tested data. All was within the 1 % manufacturers guaranteed performance.
Can we get this back on track instead of watching the same old tired players acting on the stage again pushing private agendas?
All the best,
Crumpp
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See Rule #4
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Originally posted by Crumpp
Why does every thread in this forum degenerate into "my plane is better than your plane"?
Ask Larpy.
Everyone here does know that manufacturers had tolerances specifications. They would only guaranteed performance within a percentage variation. 1 percent variation was considered good and well within tolerance. 2 mph is barely a 1/2 a percentage point from 377mph. Those tolerances were pretty broad even at 1 percent. The FW190 had a 15kph margin between the best and worst tested data. All was within the 1 % manufacturers guaranteed performance.[/B]
Indeed. From what I have seen, manufacturers would guarantee a speed performance within 3% of the nominal figures, ie. those planes 3% below official top speed were accepted, too... now if one thinks it over, that mean an 'officially' 400mph plane was accepted even if it could do only 388mph... and if you think it over again, did that 10 mph differece in top level speed reached after 2-3 minutes in straight and level flight made real difference in air combat?
Can we get this back on track instead of watching the same old tired players acting on the stage again pushing private agendas?[/B]
Just take note that I merely shared my data with others when I posted the speed loss for the 109 gondolas in a 109 thread. I really fail to see what's the problem with that... I really can't understand reactions like that : after seeing some specs for 109 gondolas, to start screaming BUT MY MUSTANGS BOMB RACKS WERE LESS DRAGGY!!!!
So don't count me in your plural, would you?
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See Rule #4
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According to German doc MG 151 Gondolas increased Cw by 0.001
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Originally posted by Kurf�rst
BUT MY MUSTANGS BOMB RACKS WERE LESS DRAGGY!!!!
[/B]
They were.:lol
.
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See Rule #4
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Originally posted by Charge
Debonair, I would say that the way you described them especially in slow speed their effect is very small if it exists at all.
They do help the contemporary airliners to save fuel at their normal cruising speeds by reducing the wingtip vortices and their effect on drag.
-C+
I was taught that winglets are to reduce induced drag & wingtip vortices which are a phenomenon of low speed flight & worst in the condition of heavy, clean & slow. I've never heard ATC tell anyone in the flight levels "caution wake turbulence", but tower & approach/departure control give this warning regularly. If this is the case, then reduce drag is akin to increased performance, isn't it? Actually maybe not. Modern aerobatic planes dont have winglets. Honestly I dont know, which is why I asked for other's opinions. You gave yours & now I'm arguing with you so I guess I'm kind of a jerk...
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I haven't heard that they work well at slow speed and that surprised me.
It's true that especially near airfields the effect of vortices can be disastrous but I don't know how much the winglets help to that problem other than keeping the descending vortice away from the top of the wing.
It doesn't make anybody a jerk if he's discussing matters in a civil manner.
Good question BTW and I'm afraid I don't know the exact answer but this is how I see it.
:)
-C+
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Oh come on, stop bashing each other with Rule #4 and so on :D
Anyway, when the discussion goes about 1% differences between PS and HP and 2 mph top speeds, - then IMHO somebody is grabbing a straw,- while at the same time nobody mentions weight difference of what, - 1000 - 2000 lbs maybe (?).
The paint is another issue. AFAIK the Germans were ahead in their finishing, so their paint weight is not a penalty. Crumpp has the numbers I belive, if I remember correctly, a good finish could make some 10 mph.
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Crumpp has the numbers I belive, if I remember correctly, a good finish could make some 10 mph.
That depends on the aircraft Angus.
Some aircraft were greatly affected by finish such as the Bf-109 and the P 51. Others like the FW190 were hardly affected at all. "Filled and Polished" adds 5kph or less on average to the FW190A.
All the best,
Crumpp
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But on a p51 it means a bit more (which is the example brought up). If they did speed tests on something where the guns were patched over, the camera hole, the shell ejection chutes, and the entire wing from the gear inwards (if I read that properly) was filled and POLISHED, I think that's a skewed non-standard result.
Had they wanted a good result they'd just have cleaned the thing and put it in the air as-is.
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Originally posted by Krusty
But on a p51 it means a bit more (which is the example brought up). If they did speed tests on something where the guns were patched over, the camera hole, the shell ejection chutes, and the entire wing from the gear inwards (if I read that properly) was filled and POLISHED, I think that's a skewed non-standard result.
Had they wanted a good result they'd just have cleaned the thing and put it in the air as-is.
Krusty,
All Mustangs' wings were primed and filled at the factory. It was in no way skewed. Quite the opposite in fact. I'll post a picture of TK589's starboard wing later- it was anything but 'Polished'. You'll see why I described it as "well used".
LRRP
EDIT: Here you go...
(http://img.photobucket.com/albums/v11/brentce/TK589swing.jpg)
See what I mean by 'well used'?
.
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Just pointing out that it is hard to tell what is photo finish and what is aircraft finish in that picture. It is an awfully green light/hue to that picture.
The report says the aircraft was coated with a smooth matt finish.
All the best,
Crumpp
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Originally posted by Crumpp
Just pointing out that it is hard to tell what is photo finish and what is aircraft finish in that picture.
Not all that tough, really. It's pretty obvious that the aircraft finish is very scuffed and worn. The picture itself has a green tinge, but other than that it is very clear.
.
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Just was reading on of my Jeppessen books & it mentioned that parasite drag increases with the square of airspeed, so it is probably not too hard to estimate the drag penalty of a bomb shackle at any speed if you know the penalty at a particular airspeed
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Originally posted by Angus
Anyway, when the discussion goes about 1% differences between PS and HP and 2 mph top speeds, - then IMHO somebody is grabbing a straw,- while at the same time nobody mentions weight difference of what, - 1000 - 2000 lbs maybe (?). [/B]
Yeah, I agree. :D
The paint is another issue. AFAIK the Germans were ahead in their finishing, so their paint weight is not a penalty. Crumpp has the numbers I belive, if I remember correctly, a good finish could make some 10 mph. [/B]
Some good friend of mine - an aviation author - a good while had some info (though a bit general) about WW2 camo paints. He said that the camo paint the jerries used was of smaller grain size than allied one, so the surface would be smoother. But paint weight is definietely a penalty, think about how much paint you would need to cover about 8-900 sq. feet area - a fighter's surface!
The doc I have also notes some 12 kph gain for the 109G if some care like polishing was done to the surface, though it would vary from plane to plane, and how much work and how many types of improvements were used.
This doc also notes this about gondolas, so I guess we can move to the next subject... ;)
(http://www.onpoi.net/ah/pics/users/715_1129371315_109g_drag.jpg)
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One can draw their own conclusions about the Mtt data, but on the 190G, the 3 different Ruckflug being mounted resulted in a 15kph, 30kph and 18kph loss of speed.
The first Ruckflug was a small little thing used on the G-2, smaller, and with no no stabilizer arms, than what is seen in the pic of the P-51D posted earlier. The second 2 Ruckflugs had 4 small stabilizer arms.
A 4th Ruckflug was used on the G-1 resulted in a 40kph loss of speed.
Data and drawings in Wagner's bio of K Tank, pg. 149, 150
Mounting the MK103 gondolas on the 190 resulted in a 27kph loss of speed.
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Some good friend of mine - an aviation author - a good while had some info (though a bit general) about WW2 camo paints. He said that the camo paint the jerries used was of smaller grain size than allied one, so the surface would be smoother. But paint weight is definietely a penalty, think about how much paint you would need to cover about 8-900 sq. feet area - a fighter's surface!
I am being somewhat misquoted. The RLM finishes are of much smaller grain than the allied paints. They are much more resistant to chipping and seem almost chaulky when cured. They wear smooth rather than chip or flake.
Weight is still a penalty but much less than the allied finishes as the RLM paints cover the surface in a much thinner coat and do not require a second coat.
All of these properties are dependant upon proper application. It took help from ex-Luftwaffe maintenance personnel to get our paint to apply correctly. It is very finicky paint requiring the proper ratio of reducer, etc...
In the field, especially in Russia, it was not always possible to get the correct components. The paint could still be applied but was then rubbed down with fuel to improve the finish.
All the best,
Crumpp
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Ruckflug
Is a condition of the aircraft Milo, not a piece of equipment. Rückflug is after the stores have been dropped.
It literally means "return flight".
The equipment is the Junkers, Mtt, Focke Wulf, and finally the ETC 503 träger.
Milo says:
One can draw their own conclusions about the Mtt data, but on the 190G, the 3 different Ruckflug being mounted resulted in a 15kph, 30kph and 18kph loss of speed.
The first Ruckflug was a small little thing used on the G-2, smaller, and with no no stabilizer arms, than what is seen in the pic of the P-51D posted earlier. The second 2 Ruckflugs had 4 small stabilizer arms.
A 4th Ruckflug was used on the G-1 resulted in a 40kph loss of speed.
Data and drawings in Wagner's bio of K Tank, pg. 149, 150
Mounting the MK103 gondolas on the 190 resulted in a 27kph loss of speed.
Say something else funny, Milo...
All the best,
Crumpp
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The following may be useful when considering Kurfurst's description of the wing treatment on the P-51 test aircraft, above. This is from the Osprey "Production Line to Frontline" book, page 16 and other pages:
"At the factory, the wings were primered and finished with airfoil smoother. The first 40 per cent of the wing chord was shot with one coat of zinc chromate primer. This was then followed by enough coats of Acme Gray Surfacer No 53N5 to cover all irregularities. Skin butt joints were then filled with Acme Red Vellunite glazing putty no 58485. The entire area was then sanded down and sprayed with one coat of camouflage enamel (when camouflage was deleted, the forward portion of the wing was sprayed silver). This was a simple and quick way to create a nearly perfect laminar flow surface, but one has to wonder just what effect all those size 12 GI boots (warn by both air- and groundcrew) in the field had on the carefully-applied laminar flow finish!."
To clarify, the book indicates that this procedure was used on all production P-51s.
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Lol, good point!
Anyway, I spent some 3 weeks recently wearing U.S.M.C. boots (as well as socks, leggings, trousers, T-Shirt, Shirt, jacket, ammo-belt, helmet, and Thompson or M1), and even with full load those boots don't have such a brutal step at all. Todays military boots are much harder on the sole.
Anyway, as espected, Crumpp brought a complete input aboput the paint. We just need some good info on the allied paint.
Am I right that in the end the U.S. used a transparent glossy paint of epoxy kind? (Those silver birds)
I mean, epoxy is really smooth and strong. Doesn't get any better, even today.
BTW what do they use today?
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I mean, epoxy is really smooth and strong.
The USAAF paints were developed by a company out of California. They are smooth and thick. The bad thing is that flexing causes them to crack around rivets and seems. These cracks then chip or peel, quickly degrading the finish. The thickness of the paint combined with the multiple coats required to completely cover the aircraft means the finish is heavy. IIRC, it adds around 250lbs to the P51.
You can see original RLM finishes here:
http://www.white1foundation.org/parts/droptank.jpg
That Kraftstoffbehälter has paint that was applied in WWII. Even after being released in flight, landing in a ploughed field and sitting in a barn, the finish is remarkably intact. Notice the bare metal spots are worn smooth around the edges and not sharp.
This is typical of RLM finishes.
Here is another part with severe wear on the finish. It is down to the primer/bare metal for much of the part. However you can see how thin the finish is and how the edges tend to feather:
http://www.white1foundation.org/parts/leadingedge2.jpg
The seat has a new finish painted with RLM paints:
http://www.white1foundation.org/parts/pilotseat2.jpg
It is generally agreed that the P51's in the field never achieved laminar flow. This is backed up by German wind tunnel test's of the wing even after it was cleaned up. Laminar flow wings were developed for the Bf-109 and the FW-190. However, given the technology of the day, it was decided that the "laminar" flow simply did not occur at speeds propeller aircraft could fly nor could surface conditions required be maintained in the field.
Unless you were flying a jet with significantly more thrust than they could develop in 1945, it was not worth the expense to produce for little to no practical gain.
The P51 came close though when cleaned up.
All the best,
Crumpp
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Thanks. Nice info.
So in the paint-war the Germans were ahead. And the effect to top speed is noticable. And the weight penalty is then not equal, - or at least not on the German side.
Laminar flow was not achieved in WW2 with any considerable effect AFAIK, although perhaps with the todays Reno race Mustangs, - I remember seeing something about that. Several coatings I belive.
But what about rivets? All flushed by the 109? 190? Just really thought of this. Spitfires? P47's?
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But what about rivets?
Most fighters in WWII had flush riveting construction. The riveting still leaves a surface impression at the seam. It is this seam that causes the cracking when the frame is flexed in flight with the allied epoxy paints. This cracking leads to chips and peeling.
All the best,
Crumpp