A-1 Skyraider vs A-26

[Elvis]

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.

Hey GregP,

Ok, look, this is going to turn into a shouting match pretty quick if cooler heads don't prevail. You're obviously a learned guy and I can appreciate that.
Thank you for your contributions to this website.
I think I made a valid point with the fact that if one plane can turn inside the other, it should be able to complete the turn quicker than the other.
I wasn't "poo-poo-ing" on anyone or any one aircraft with the figures I posted earlier.
my original point was simply to let everyone here know that there's other info out there (or maybe was?) that could be relevant to this thread and no one else had mentioned it yet, so I thought I would.
That was all.
Please forgive me for trying to contribute to this thread without gaining a masters in Aerodynamics first.
Still searching for that thread. That info is buried out there, somewhere. I will post a link when/if I find it, but as for the rest. I'm done.
Have fun, guys.


Elvis

 

[drgondog]

Hmmm, wondering why it would turn into a shouting match. GregP presented the math to let you play with different variables and draw your own conclusions.

 

[Robert Porter]

Honest Elvis, I have never seen GregP shout at anyone, nor even seriously remonstrate. I sincerely doubt he was headed anywhere near that direction. As drgondog mentioned he was facilitating all of us to learn a bit by discussing the math involved. I think you raised some interesting points yourself, but I truly do not think GregP or anyone else was attempting to shut you down as they say. I have royally put my foot in my mouth during a few threads and GregP has always been the one to use reason not vitriol to make his point. I truly hope you did not misunderstand. Please do find the thread you were talking about and post the link. We all learn something from these conversations.

 

[swampyankee]

From the little I know about any pre-missile combat flying, there's a significant amount of time spent in the high-alpha range, so behavior near stall is very important, especially so for the comparatively inexperienced pilots entering combat during, say, the Battle of Britain. I think some of that came out in the Spitfire vs Bf109 turning tests, where experienced pilots consistently got better turning performance out of the aircraft than less-experienced ones. It also places concerns for good handling and well-balanced controls in context.

 

[BiffF15]

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

Elvis,

You are correct up to a certain point. If a Bf-109 was traveling North with an A-26 1500' behind and subsequently went into a hard left turn. With the trailing A-26 staying pure pursuit (pointing at the 109), he will cut across the circle and have a fleeting snap shot (as long as said 109 pilot stays in the turn - not smart). The Invader will travel less distance until he overshoots the turn circle of the 109. He flew less distance only because of angular cutoff, not because his plane turns better. After overshooting the 109, with both at best turn, the 109 will in short order run around his turn circle (smaller that I'm assuming it is as well) and arrive at a gun solution on the Invader.

It's hard to do this without a drawing, just realize that the A-26 will have a circle much larger circle than the 109. I flew the Eagle against many adversaries that had better turn circles than me, but learned there are other options / tools that worked when applied properly.

Cheers,
Biff

PS. In my opine Greg meant only to exchange info.

 

[Zipper730]

About that.

Thanks

From the little I know about any pre-missile combat flying, there's a significant amount of time spent in the high-alpha range, so behavior near stall is very important, especially so for the comparatively inexperienced pilots entering combat during, say, the Battle of Britain. I think some of that came out in the Spitfire vs Bf109 turning tests, where experienced pilots consistently got better turning performance out of the aircraft than less-experienced ones.

Yup. There were other things such as gunnery skill... without a lead-computing sight a lot more work had to be done by the pilot.

Elvis,

You are correct up to a certain point. If a Bf-109 was traveling North with an A-26 1500' behind and subsequently went into a hard left turn. With the trailing A-26 staying pure pursuit (pointing at the 109), he will cut across the circle and have a fleeting snap shot (as long as said 109 pilot stays in the turn - not smart). The Invader will travel less distance until he overshoots the turn circle of the 109. He flew less distance only because of angular cutoff, not because his plane turns better. After overshooting the 109, with both at best turn, the 109 will in short order run around his turn circle (smaller that I'm assuming it is as well) and arrive at a gun solution on the Invader.

It's hard to do this without a drawing, just realize that the A-26 will have a circle much larger circle than the 109.

From what I'm guessing you're describing something like in basketball where if I'm the defender I don't have to turn much to stay with a faster player because he's heading towards the basket and I'm already nearer. As he gets closer I have to do more and more work to stay with him.

 

[GregP]

Hi Elvis,

Not upset in the slightest at anybody(excluding the odd politican or three), let alone you. If I sounded that way, I apologize ... not intended. Sometime I sound different than I intend. Seems to go with being an engineer or maybe I'm just not too good at voicing the right words.

Any plane can maybe turn inside any other plane, but if the speed and g-force are held constant, neither can since they will both fly the same track. You probably know that, while WW2 military planes are all strong, they have different amounts of excess power and differening wing sections (different lift coefficients). Usually one or the other can sustain a higher load while staying level in a turn, and it is usually called the more maneuverable aircraft of the two ... IF they need to stay level. That is not the case at 25,000 feet, but definitely IS the case if they are mere feet above the treetops over a forrest or out over the Russian steppes.

Once at ground level, the real better-maneuvering aircaft will rather quickly emerge and still be aviating.

Perhaps I was splitting hairs (unintentional), but I suppose engineers are doomed to do that most of the time.

Cheers to you!

One of the two planes usually CAN out-turn the other one, sometimes even if they are flying the same type airplane, just because one pilot or the other is slightly better at sensing his plane's condition near the stall. If he isn't very good and is low, he can easily pull just too hard and snap roll right into the ground. That happened often in Russian, according to the Soviet fighter pilots, when Bf 109s or Fw 190s tried to follow Yak-3s and La-5s in a tight turn close to the ground.

I wasn't there, but have read the reports. Of course, and as an aside ... covering their butts might also be the real case since any cowardice or even loss might have resulted in a firing squad. I don't know. It was hard not to be somewhat protective of one's reputation in the Soviet Union while Stalin was around. He wasn't known or even suspected of being exactly understanding of subordinates. And EVERYONE was a subordinate to Uncle Joe. I believe he is credited with executing some 500,000 and sending between 3 and 12 million to the labor camps (gulags) from 1934 - 1939. It was not wise to draw his attention. So maybe the victory reports were merely self-protection. Maybe not.

Nothing else implied or intended in the reply.

 

[Zipper730]

Two questions

1. The A-1 Skyraider was said to be an 8g airplane: Does that mean 8g ultimate or 8g x 1.5?

2. Could the A-1 generate a tighter turn-rate (sustained, instantaneous, or both) than the P-47D & N series under the following conditions

1. A-1 devoid of bombs, fully loaded guns, fuel-load seen after bombs away; P-47D & N without drop-tanks, fully-loaded guns, no bombs, and fuel-loads typically seen in combat missions of medium range (more specifically non escort missions where the fuel tanks are almost totally loaded)
   
2. A-1 as before; P-47D & N with a light/moderate bomb-load and fuel loads typically seen before bombs-away
   
3. A-1 with a bomb-load of around 1,000-2,000 pounds and fully loaded guns; P-47D & N with similar load and cannons loaded as much as permitted
   
4. A-1 with a 4,500 pound bomb-load, ammo as permitted; P-47D & N with maximum bomb-load and reduced gun armament as required for high weight operations

 

[XBe02Drvr]

Two questions

1. The A-1 Skyraider was said to be an 8g airplane: Does that mean 8g ultimate or 8g x 1.5?

Think about it Zipper. If it's 8G ultimate, that makes flight limit about 5.3. Would you be willing to dive bomb the bridges at Koto Ri, through the flak and the Migs, hauling 4,000 lbs of bombs on a 5G airplane? Not this turkey!! Hell, that's only a little more than the flight limit for a Utility Category civil aircraft. (4.4G)
That rumble you're feeling underfoot is Ed Heinneman rolling over in his grave!
Cheers
Wes

 

[GregP]

You need to read some about aircraft design.

The questions show a lack of reading about the subject, and you keep doing it on a regulat basis. We have some hundreds of threads on these topics, but the thread title doesn't aways betray the information conveyed beacause people, rather obviously including me, keep straying away from the thread subject.

This thread is not about aircraft ultimate strength or P-47s; it's about the A-1 versus A-26. Start another thread on unrelated questions, please! And ... ME too!

Aircraft strength has been very well covered in threads, as has the P-47, but the P-47and Skyraider were not contemporaries. The P-47 was rapidly replaced in service after the war, probably due to the expense of building and operating the complex systems. The Skyraider was almost cancalled several times during the 1940s/1950s, but survived to be a formidable aircraft in Viet Nam and other limited-war areas. It virtually never operated with the P-47, so I'm not sure why you'd be asking. It's like asking if we'd rather fly a Douglas Skynight or a Ta-152? They were not contemporaries, so the real answer would be, "Did you mean 1945 or 1952, day fighter or night fighter? They didn't fly the same skies!" ... except maybe in video games.

 

[tyrodtom]

One country that did operate the P-47 in a combat role long after WW2 was the ROC, Taiwan.

If you'll look at Fahren's list of cold war shoot downs that he posted in the Lend lease during the Korean War, you'll see a lot of ROCAF P-47s getting shot down over China well into the 50's.

 

[tomo pauk]

Two questions

1. The A-1 Skyraider was said to be an 8g airplane: Does that mean 8g ultimate or 8g x 1.5?
...

G limit, on design and combat load (weight of aircraft = 15 to 15.5 thousand lb) was 6, for the AD-4. link

 

[XBe02Drvr]

G limit, on design and combat load (weight of aircraft = 15 to 15.5 thousand lb) was 6, for the AD-4. link

So the flight limit was 6 and the ultimate around 9? Considering the instantaneous overloads encountered due to turbulence, flak, and pucker factor, dive bombing in a Spad doesn't strike me as such a wholesome activity all of a sudden. You've shattered my mystique for the old girl!
Cheers,
Wes

 

[GregP]

I've seen another design document for the AD-1/6 (single-seat, not 4-seat) where the limit was 7g with a light bomb load, less when heavy, and 8g when the bombs were gone but still had fuel and ammo remaining. Haven't found that one in several years, though. It WAS floating about some years back.

The intent, I surmised from the rather strange g-limits, was to have the Skyraider be at standard fighter strength when configured-by-default as a "fighter" on the way home from dropping ordnannce. But ... it may have just seemed that way to me since I KNEW the general operating history of the Skyraider in the real world.

Originally, it COULD have been intended to actually be USED as a fighter, not primarily, but if necessary, to defend carriers. The Skyraider WAS designed in WWII, and that might have been a consideration at that time ... I do not claim to know nor make that claim. It's just a thought. But we all know the g-limit falls as weight grows, and it COULD haul 8,000 pounds of bombs. It rather obviously was never going to be an 8g aircraft at that weight. When it was light, 6g may have been plenty to yank it around with all that wing area! I have always loved the dive flaps and still do when they demonstrate them at an airshow.

Before he passed away, Bob Grondzik (Skyraider Bob, aircraft number 500 for years ... AD-6) used to climb, dive and deploy the dive flaps at our annual airshow at Chino every year. Definitely worth the wait. Those speed brakes were enormous and stick out on either side and the bottom some 4 - 5 feet! Once in awhile, he'd take a passenger [in the fuselage jump seat(s)] and I'm sure they regretted being along for the ride about pullout time. They were facing backward and had a very limited view outside (small window, a few feet away from the seat). Probably had spare rags floating about in the compartment since they used several (or many) getting the oil off it when they landed, every time.

Impressive bird. I wonder who got it, but have never asked around the museum.

Here's a shot of his plane with dive brakes out:

It's SHOWN more or less horizontal above, but he never deployed them unless diving pretty steeply when I saw him do it several times. Might just be a photo shoot pic ... can't say.

The Skyraider was originally the XBT2D and the other competitors in the race were Martin XBTM Mauler, the Curtiss XBTC, and the Kaiser-Fleetwings BTK. All were competing to replace the Curtiss SB2C Helldiver. Due to the US Navy's concern that the Curtiss design was overly complex and that the company's record was particularly poor during the Helldiver's development, Martin was instructed to create an "unexperimental" design that would be a reliable platform for the Pratt & Whitney R-4360 Wasp Major radial engine that powered both aircraft. So the Curtiss XBTC and Martin XBTM both used the R-4360, the XBT2D used the R-3350, and the BTK used the R-2800 (putting it as a serious power disadvantage).


The XBT2D won the competition.

 

[XBe02Drvr]

When it was light, 6g may have been plenty to yank it around with all that wing area!
Before he passed away, Bob Grodzik (Skyraider Bob, aircraft number 500 for years)

When light, the Spad had amazing agility, with its powerful flight controls, its ability to "stand on the brakes" and the instant thrust available when all those 3350 cubes were unleashed. Enough to surprise and kill the occasional unwary jet over the years.
The 500 on the cowling is not an aircraft number, at least not in the sense of a serial number or a Bureau Number. It's an air wing number. Back in the day each tactical squadron in an embarked air wing had a digit assigned between 1and 9. Each aircraft in the squadron had two digits after the squadron digit that represented the place in the squadron command hierarchy of the pilot whose name was painted below the cockpit. 00 ("double nuts") wore the CO's name. The usual sequence of squadron digits, IIRC, was: fighters/fighter-bombers/light attack/all-weather attack/heavy attack/recon/ASW in that order. The detachments, helicopters and AEW, usually had their own numbering system.
Cheers
Wes

 

[GregP]

Hery XBe02Drvr,

Probably a stupid question, but is a Be 02 basically a Beech 1900? Or is it a Beriev?

 

[Zipper730]

G limit, on design and combat load (weight of aircraft = 15 to 15.5 thousand lb) was 6, for the AD-4. link

Okay, so normal g-load is 6 and ultimate load is 9g at rated and combat load... did this apply for early variants?

The questions show a lack of reading about the subject

I couldn't find anything so I asked people here. I doubt anybody else would short of somebody who flew them, hence my questions.

We have some hundreds of threads on these topics, but the thread title doesn't aways betray the information conveyed beacause people, rather obviously including me, keep straying away from the thread subject.

The reason I went into g-load was for several reasons

1. A g-load provides an exact turning arc at an exact speed in level flight.
   
2. This thread was about comparisons of the A-1 and A-26: The idea was to figure out either turning circles or g-loads to figure out how they'd compare.

This thread is not about aircraft ultimate strength or P-47s; it's about the A-1 versus A-26.

I wasn't actually focused so much on the ultimate strength in this case (far as I know it's 7.33gx1.5), it was more the turning arc as a reference point of comparison.

• Provided the claim about the A-26 able to turn inside the Me-109 with bombs off being valid, I was basically curious how the A-1 compares bombs off and on
• The A-1 was able to get inside the La-7 and La-9 at times during the Korean War: I attempted to find out how the performance of the La-7 & La-9 was compared to the La-5 as there's comparisons of the La-5 to the Me-109 and Fw-190; from what I got from watching a film that was in Russian and had English subtitles, the La-7 seemed quite favorably compared to the La-5 in terms of speed and was well regarded for maneuverability (same?) provided the film was accurate.
• The P-47 was commonly used in ground attack and I was curious how they compared

The Skyraider was almost cancalled several times during the 1940s/1950s

I didn't know that...

I've seen another design document for the AD-1/6 (single-seat, not 4-seat) where the limit was 7g with a light bomb load, less when heavy, and 8g when the bombs were gone but still had fuel and ammo remaining. Haven't found that one in several years, though. It WAS floating about some years back.

Fascinating

The intent, I surmised from the rather strange g-limits, was to have the Skyraider be at standard fighter strength when configured-by-default as a "fighter" on the way home from dropping ordnannce.

That makes some sense

Originally, it COULD have been intended to actually be USED as a fighter, not primarily, but if necessary, to defend carriers. The Skyraider WAS designed in WWII, and that might have been a consideration at that time ... I do not claim to know nor make that claim. It's just a thought.

Makes some sense actually, some SBD's were used to defend carriers in 1942. Ironically one pilot with mad skills managed to knock out 2 A6M's and get clipped by a third (it was counted as a kill as they went down). His name was Vejtasa I believe.

Here's a shot of his plane with dive brakes out:

Boy, those are some big-ass brakes!

The Skyraider was originally the XBT2D

That I know...

 

[XBe02Drvr]

Hey Greg,
Don't I wish it was a Beriev! Love to log some turbine multi-engine seaplane time. That's pretty rare stuff.
Nope it's ATC code for a plain old pedestrian Beech 1900C (the hunch-back version, not the stand-up one). A blast to fly, but not much fun to ride in. 2200 horsepower on a MGTOW 17,000 pound airframe made it a lively performer though it's high lift airfoil for short runways limited its high end speed. Metroliners and Jetstreams used to blow us into the weeds (but they couldn't land on 33 Right at BOS). The engines were derated from 1400 horsepower, thus had good altitude performance, and at mid-payload weights were capable of near neck-snapping acceleration. The controls were light, smooth, well balanced, and quick, and she would stand on a wingtip in the bat of an eye if you weren't careful. Think "bank" and it happens. Regular Walter Mitty fighter plane. It was always fun flying with someone who had just transitioned from a more truckish airplane, especially retired SAC pilots, which we seemed to attract quite a few of. They had a tendency to startle the passengers until they got the hang of it.
One thing we could do that almost nobody else could, was expedite a descent AND a speed reduction simultaneously. Lose 5,000 feet and 50 knots in under 2 minutes and all without the passengers getting anxious. Very useful in crowded terminal airspace when a controller wants to make use of a gap in the traffic.
Southbound over Manhattan at 6 thousand and 210 knots: "Brockway four twenty six, your traffic is an Eastern seven two, nine o'clock two miles at two thousand northbound over the tanks on the Expressway Visual, also a Piedmont seven three over the Verazanno at three. Report in sight." "Brockway has both Boeings." "Brockway four twenty six, turn left and follow the Eastern seven two, descend and maintain two thousand. Expedite. Slow to one six zero. Expedite. Leaving three you're cleared the Expressway Visual, three-one at Laguardia. Maintain visual separation." "Piedmont six forty three, slow to one sixty, then descend and maintain two thousand. Your traffic to follow is a Beech airliner eleven thirty and five miles, out of six for two. Report in sight."
The bird was so lively and capable of scaring the passengers we used to joke about "two terrorists and nineteen hostages".
Cheers,
Wes

 

[tyrodtom]

Zipper730, where did you get the information that the A-1 could get inside the La5 or La7 ?

The only recorded incidents of A-1/ La incidents i'm aware of that resulted in shoot downs occured after the Korean war, and the A-1s came out on top mainly because the La-5, 7, or 9 were badly flown. Probably low time PROC pilots verses veteran Navy pilots.

 

[drgondog]

For general rules of thumb - If you want the actual design Limit loads for any aircraft, you need to see the structural analysis. The Structural analysis report will state the +/- G for a specific weight condition and - as a rule of thumb - will be based on maximum AoA loads imposed usually in a pull out from a dive.

The loads that are imposed on the airframe are both the aerodynamic loads, including theoretical Center of Pressure on wings and horizontal Stab/Elevator combination as well as inertial loads applied to the airframe.

The structural analysis begins with the Specification statements regarding mission and design Limit loading for the extreme 'Normal' (Dive pull out, carrier landing loads for a non-combat aircraft (COD, rudder loads due to low speed/high propeller torque, etc., etc.) where the Forces are applied to a rigid airframe conceptual model and the Force vectors are applied about the theoretical Center of Gravity and Bending moments are also calculated about the CG. The essential outcome is a Force and Moment balance about the X, Y, Z axis.

Pertinent to this forum is that not much attention was given to fatigue life or thermal stress analysis and aero elasticity considerations were in the infancy stage of analysis. Flutter analysis was also in early stages and often followed "We have a problem" during flight tests.

The initial work proceeds with Preliminary Design and is iterated during the Development process as detail design considerations are balanced with practical design approaches for such structure as wing spars, bulkheads, etc., manufacturing processes, etc. During this process issues are always uncovered with matching design to the desired Spec and compromises are developed and implemented. There is a lot more to say about this process - but.....

For WWII spec framework for US aircraft the fighters were all (to my knowledge, except for P-51H) framed around 8G Limit and 12G Ultimate in which the design limit loads were analyzed part by part to achieve (STRESS ALLOWABLE)/(STRESS ACTUAL)-1 >.01 for the material properties of the part(s).

Bombers and transports were generally designed to +3G/-1.5G for a Design/Spec Gross Mission Weight. Not overload or Maximum Gross weight, but design mission Gross weight for fuel, ammo and payload. I suspect but do not know that Dive Bombers were designed to fighter specs.

Perhaps pertinent to the wanderings regarding "turn rate" and "turn radius", it is perhaps important to re-state two or three facts about airframes with big engines in asymmetric/high Angle of Attack flight.

Airframes and wing are flexible - some more than others, When aerodynamic loads are combined with inertia loads, wings twist which affect the actual AoA achievable before a CLmax (other than theoretical airfoil and wind tunnel results for symmetric flight (no yaw for example. The aerodynamic pressure distributions are altered significantly.

Engine/Prop systems at low speeds - are a.) less efficient and b.) promote more significant gyroscopic loads, proportionally, which control surfaces must offset (a reason why that a/c turns better in one direction).

Drag - The Parasite drag increases due to increases in CL are Significant and must be accounted for in developing the forces applied to the airframe to derive 'turn performance'. Ditto Cooling Drag at relatively low speeds like Corner Velocity.
In the airframe biz for conventional aircraft, the methodology for high Aoa (climb/Turn) pointed to developing the analytics to calculate Power Available and Power Required. The reason is that the vagaries of precise calculation for Thrust (engine/prop + exhaust) is tougher.

I am not available to answer a barrage of questions at the moment, but take this to the bank. The equations developed to calculate Turn as a function of CL, GW, Wing Area, Density and Velocity fall apart when one tries to insert Theoretical CLmax for level stall. Actual CLmax is significantly less for all the reasons outlined.