A-1 Skyraider vs A-26

[XBe02Drvr]

Hey Zipper, ditto all above. The man knows whereof he speaks. And remember, not every kill results from "getting inside the victim's turn". A heavier more powerful aircraft will likely choose to go vertical on a lighter weight, tighter turning opponent.
Cheers,
Wes

 

[tyrodtom]

I wonder how in the test they performed back in the WW2 era how they determined the diameter of the circles the aircraft turned in, they assigned values sometimes in feet, yards, or meters. They had no GPS on anything of that sort, and at the altitudes most test were performed, they'd have no way to equate it to a circle on the ground.
Was it just a WAG?

They could tell how a certain aircraft, equipped a certain way , at a certain altitude, with a certain pilot flying , could compare to another aircraft at that time under the same variables.
But to assign a definite fixed value to the tests ? Was it just BS to help morale ?

 

[XBe02Drvr]

Radar?? An AI radar in an aircraft flying level at constant speed on a track that would bisect the circle after the turn was complete would give a series of range and azimuth plots that could be corrected for the radar aircraft's travel to give a plotted circle. Probably too sophisticated for the equipment of the time. I know the ACM range radar in my day could do it. A nugget who was not getting the most out of his airplane was readily apparent to the range operators and ACM instructors watching.
Cheers,
Wes

 

[XBe02Drvr]

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.

Those PROC pilots were probably US trained. In the latter part of WWII, Chiang Kai-Shek sent hundreds of "loyal Nationalist" young men to be trained ab initio as fighter pilots. I've spoken with some of their instructors. These guys were in danger of losing their draft deferments due to the scaling back of the massive contract flight training program. It seems air combat losses were lower than forecast, while infantry losses were much higher, and there was a desperate need for cannon fodder. Well along comes this Lend-Lease Chinese training program to save the day.
They said these Chinese kids were challenging to teach, as most had been yanked right out of ox-cart culture into the twentieth century. It was especially hard to get them to think in the vertical dimension.
Well, long story short, the majority of them eventually wound up flying for Mao, albeit in aircraft and culture vastly different than their training (most didn't get to take their Mustangs or Thunderbolts with them). Also, most were grounded while they went through lengthy "political reeducation", so, far from current at flying, then subjected to a radically different aviation culture in radically different aircraft by Russian instructors who were as racially and culturally contemptuous of them as the Americans had been. Then they were issued life-limited airframes that didn't allow enough monthly flying time to achieve and maintain proficiency. The same almost-starvation monthly rationing of caloric intake that applied to the population as a whole applied to fighter pilots, too, so their G tolerance probably was far from optimum, not to mention their mental alertness and visual acuity.
Up against combat veteran Navy pilots in agile, well armed Skyraiders, not much of a fair fight. In this context, theoretical tightest turning radius of an LA-7 is hardly relevant to anything. (How many angels can dance on the head of a pin, Mr. McNamara?)
Cheers
Wes

 

[swampyankee]

I fail to see what Mr McNamara has to do with any of this discussion, but who am I to judge?


One thing when comparing the AD vs WW2-era fighters, like the La-7, is that piston-engined aircraft were probably quite close to the absolute limits on possible performance: a light AD Skyraider would be closer in performance to an La-7 than the "attack" vs "fighter" classification would show: it may have been a bomb truck, but that meant that it had a big wing and a lot of surplus power at light weight. It also had all those landing on carrier concerns, so it probably has quite good behavior at high angles of attack. If the La-7 pilots are trying to get into a turning fight, this would probably not be a good plan.

And the MiG-15/MiG-17 drivers who got shot down by ADs should just go to their commanders and volunteer for duty cleaning latrines.

 

[wuzak]

I fail to see what Mr McNamara has to do with any of this discussion, but who am I to judge?


One thing when comparing the AD vs WW2-era fighters, like the La-7, is that piston-engined aircraft were probably quite close to the absolute limits on possible performance: a light AD Skyraider would be closer in performance to an La-7 than the "attack" vs "fighter" classification would show: it may have been a bomb truck, but that meant that it had a big wing and a lot of surplus power at light weight. It also had all those landing on carrier concerns, so it probably has quite good behavior at high angles of attack. If the La-7 pilots are trying to get into a turning fight, this would probably not be a good plan.

And the MiG-15/MiG-17 drivers who got shot down by ADs should just go to their commanders and volunteer for duty cleaning latrines.

Using specs from Wiki I get the Skyraider had 4.433lb/hp at empty weight (ie no fuel or ammo) while the La 7 had 4.429lb/hp at gross weight.

So not a lot of surplus power.

 

[wuzak]

I wonder how in the test they performed back in the WW2 era how they determined the diameter of the circles the aircraft turned in, they assigned values sometimes in feet, yards, or meters. They had no GPS on anything of that sort, and at the altitudes most test were performed, they'd have no way to equate it to a circle on the ground.
Was it just a WAG?

They could tell how a certain aircraft, equipped a certain way , at a certain altitude, with a certain pilot flying , could compare to another aircraft at that time under the same variables.
But to assign a definite fixed value to the tests ? Was it just BS to help morale ?

I think they tested what they could, such as Cl, and then calculated the turn radius.

In case of the Spitfire I vs the Bf 109E, that is what the RAE did. Flight test with both aircraft were used to test different defensive and attacking scenarios, including which one out-turns the other. The results of that would show that the Spitfire could turn inside the Bf 109, and could get on the tail of the 109 in X number of turns.

 

[Zipper730]

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

It was mentioned in this thread...

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.

That makes enough sense

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.

Okay

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.

And I assume the math for this is quite massive?

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.

Of course

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).

Now that's interesting: I thought it was 7.33 x 1.5 (not sure where that came from).

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.

Gotcha

I suspect but do not know that Dive Bombers were designed to fighter specs.

Logical

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.

Due to the twisting of the wings?

Engine/Prop systems at low speeds - are a.) less efficient

Wait, I thought propellers worked better at low-speeds?

b.) promote more significant gyroscopic loads, proportionally, which control surfaces must offset (a reason why that a/c turns better in one direction).

Not to mention torque and p-factor...

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'.

Because of greater amounts of lift produced by pulling higher g-loads, as well as variables such as flexing of wings?

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.

To allow accurate prediction

The reason is that the vagaries of precise calculation for Thrust (engine/prop + exhaust) is tougher.

And cooling drag

IThe 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.

So in a turn, the CLmax is less in a level stall than a turn?

Those PROC pilots were probably US trained. In the latter part of WWII, Chiang Kai-Shek sent hundreds of "loyal Nationalist" young men to be trained ab initio as fighter pilots. I've spoken with some of their instructors. These guys were in danger of losing their draft deferments due to the scaling back of the massive contract flight training program. It seems air combat losses were lower than forecast, while infantry losses were much higher, and there was a desperate need for cannon fodder. Well along comes this Lend-Lease Chinese training program to save the day.
They said these Chinese kids were challenging to teach, as most had been yanked right out of ox-cart culture into the twentieth century. It was especially hard to get them to think in the vertical dimension.

That would explain things..

Well, long story short, the majority of them eventually wound up flying for Mao, albeit in aircraft and culture vastly different than their training (most didn't get to take their Mustangs or Thunderbolts with them). Also, most were grounded while they went through lengthy "political reeducation", so, far from current at flying, then subjected to a radically different aviation culture in radically different aircraft by Russian instructors who were as racially and culturally contemptuous of them as the Americans had been. Then they were issued life-limited airframes that didn't allow enough monthly flying time to achieve and maintain proficiency.

So they were undertrained...

The same almost-starvation monthly rationing of caloric intake that applied to the population as a whole applied to fighter pilots, too, so their G tolerance probably was far from optimum, not to mention their mental alertness and visual acuity.

Never thought about that

Up against combat veteran Navy pilots in agile, well armed Skyraiders, not much of a fair fight.

No

In this context, theoretical tightest turning radius of an LA-7 is hardly relevant to anything.

I simply brought up the La-7 because it was mentioned earlier. I see your points though.

a light AD Skyraider would be closer in performance to an La-7 than the "attack" vs "fighter" classification would show: it may have been a bomb truck, but that meant that it had a big wing and a lot of surplus power at light weight. It also had all those landing on carrier concerns, so it probably has quite good behavior at high angles of attack. If the La-7 pilots are trying to get into a turning fight, this would probably not be a good plan.

Some truth to that

 

[tyrodtom]

Zipper730, i'm the one who brought up the fact that A1's had shot down some Lavochkins AFTER the Korean war, exactly what model Lavochkin nobody knew at the time. La5, 7, 9 11, ?

I'm the one that brought La? verses A1 up, me or no one else in this thread has suggested that a A1 could turn inside a Lavochkin of any model, other than you.


















t

 

[XBe02Drvr]

Zipper730, i'm the one who brought up the fact that A1's had shot down some Lavochkins AFTER the Korean war, exactly what model Lavochkin nobody knew at the time. La5, 7, 9 11, ?

I'm the one that brought La? verses A1 up, me or no one else in this thread has suggested that a A1 could turn inside a Lavochkin of any model, other than you.

I suspect Zipper equates a kill with getting inside your victim. "Can't have one without the other!" Someday he'll learn.
Cheers,
Wes

 

[XBe02Drvr]

I fail to see what Mr McNamara has to do with any of this discussion, but who am I to judge?


One thing when comparing the AD vs WW2-era fighters, like the La-7, is that piston-engined aircraft were probably quite close to the absolute limits on possible performance: a light AD Skyraider would be closer in performance to an La-7 than the "attack" vs "fighter" classification would show: it may have been a bomb truck, but that meant that it had a big wing and a lot of surplus power at light weight. It also had all those landing on carrier concerns, so it probably has quite good behavior at high angles of attack. If the La-7 pilots are trying to get into a turning fight, this would probably not be a good plan.

And the MiG-15/MiG-17 drivers who got shot down by ADs should just go to their commanders and volunteer for duty cleaning latrines.

Zipper has earned the callsign "McNamara" for his obsession with mathematizing everything.
As for the Skyraider's Mig victims, they should go punch their intelligence officer in the nose for not warning them of the rattlesnake nature of their opponent. "Know thine enemy!"
Cheers,
Wes

 

[Shortround6]

Wait, I thought propellers worked better at low-speeds?

Compared to a jet engine yes.

But a prop plane in a turn (if the turn lasts very long) is going slower than full speed, perhaps a lot slower and no propeller is equally efficient at all speeds. A reason that bombers and transport planes used bigger diameter propellers than fighters even if they used the same engine.

 

[XBe02Drvr]

Compared to a jet engine yes.

But a prop plane in a turn (if the turn lasts very long) is going slower than full speed, perhaps a lot slower and no propeller is equally efficient at all speeds. A reason that bombers and transport planes used bigger diameter propellers than fighters even if they used the same engine.

Plus the slower the airspeed the more angle of attack it takes to stay up, so the more the thrust line diverges from the flight path. Only the flight path component of the thrust vector is useful propulsion.
Also, the greater the angle of the prop shaft to the relative wind, the more variation there is in propeller blade AOA around the propeller disc. Thus at only two positions in the propeller disc are the blades operating at the optimum AOA that the governor is seeking. Everywhere else around the disc the AOA is greater or less than optimum.
Cheers,
Wes

 

[XBe02Drvr]

So CLmax is less in a level stall than a turn?
So they were undertrained...

Jees, man, get a clue! DrGondog knows his stuff and explained it in plain English, then you turn it around and get it back-to-front!
The greatest CLmax occurs in straight-and-level flight, 1G, minimum airspeed: your basic power-off stall. In an accelerated stall such as you might encounter in a combat turn the aircraft's lift vector is near 90 degrees to the force of gravity, the G load is high and so is the stall speed, and for all the reasons quoted by DrGondog, the (rather violent) stall break occurs long before the straight-and-level power-off CLmax is reached. If there's the slightest assymetry in airflow, one wing stalls a split second before the other, and the plane stalls with a neck-wrenching helmet-bashing corkscrew motion. If you're flying an early generation jet, the airflow disruption is apt to flame-out your engine. "Check six, there's a Mig on your tail!" Have fun!
Cheers,
Wes

PS: Those PROC pilots weren't undertrained, they were underproficient due to their degraded physical condition and insufficient monthly flying time to stay sharp.

 

[swampyankee]

I wonder how in the test they performed back in the WW2 era how they determined the diameter of the circles the aircraft turned in, they assigned values sometimes in feet, yards, or meters. They had no GPS on anything of that sort, and at the altitudes most test were performed, they'd have no way to equate it to a circle on the ground.
Was it just a WAG?

They could tell how a certain aircraft, equipped a certain way , at a certain altitude, with a certain pilot flying , could compare to another aircraft at that time under the same variables.
But to assign a definite fixed value to the tests ? Was it just BS to help morale ?

If you have acceleration, true air speed, and rate of descent, you can determine turn radius.

 

[GregP]

Drgondog (Bill) stated the facts. He is correct. No use trying to turn it around somehow and getting it wrong in other words. If you agree with someone, there is a little button at the bottom of the text area with a "thumbs up" icon. If you click it, it means agree. Beats the hell out of a 2-page reply of agreement.

Read it and try to understand the underlying aerodynamic phenomenon. If you do, there's no point asking if the pilot made a mistake. Bill didn't say anything about pilots; just aerodynamics. The things Drgondog quotes assume a properly-flown aircaft. The rest is human interaction, and is subject to anything. So the aerodynamicist assumes the pilot will fly it right at the edge of what is possible, because of the very fact that it is possible to get that performance. Possible aerodynamic poerformance has nothing whatsoever to do with pilot training or actual piloting.

People have been shot down because they were weary and sleepy. Doesn't mean they were normally bad combat pilots. It means they had an attention lapse (happens in a multi-hour flight, regardless of WHO you are), got caught unaware of the present circumstances, and paid for it. Combat typically leaves little room for error, and any luck is somewhat randomly good or bad luck. If your opponent is a cagey combat veteran, your luck is usually bad, but maybe not. Serendipity happens, too.

 

[drgondog]

I wonder how in the test they performed back in the WW2 era how they determined the diameter of the circles the aircraft turned in, they assigned values sometimes in feet, yards, or meters. They had no GPS on anything of that sort, and at the altitudes most test were performed, they'd have no way to equate it to a circle on the ground.
Was it just a WAG?

They could tell how a certain aircraft, equipped a certain way , at a certain altitude, with a certain pilot flying , could compare to another aircraft at that time under the same variables.
But to assign a definite fixed value to the tests ? Was it just BS to help morale ?

It could be as simple as standing next to a very visible marker in a field with a stop watch. The pilot/test a/c flies over and pulls G's keeping note of the airspeed until he comes back to the marker. Repeat process, and do not stall out. When he stalls out - the prior time rules. Get another pilot, repeat - but in opposite direction. Prior to test, report on load out and any treatment of external drag items (like covering gun ports, sanding surface with fine grit, etc).

 

[wuzak]

It could be as simple as standing next to a very visible marker in a field with a stop watch. The pilot/test a/c flies over and pulls G's keeping note of the airspeed until he comes back to the marker. Repeat process, and do not stall out. When he stalls out - the prior time rules. Get another pilot, repeat - but in opposite direction. Prior to test, report on load out and any treatment of external drag items (like covering gun ports, sanding surface with fine grit, etc).

Did they have G-meters then?

If they can record G levels and speed they can calculate the radius.

I believe they did have recording instruments that put the data on paper.

 

[tyrodtom]

It could be as simple as standing next to a very visible marker in a field with a stop watch. The pilot/test a/c flies over and pulls G's keeping note of the airspeed until he comes back to the marker. Repeat process, and do not stall out. When he stalls out - the prior time rules. Get another pilot, repeat - but in opposite direction. Prior to test, report on load out and any treatment of external drag items (like covering gun ports, sanding surface with fine grit, etc).

If I understand this correctly they'd keep doing this test with pulling tighter and tighter turns until the aircraft stalls out, if you know the airspeed, and the minimum amount of time it takes you complete a non stalled 360, you can compute the turning circle diameter from that .
OK, I can see that.

 

[swampyankee]

Zipper has earned the callsign "McNamara" for his obsession with mathematizing everything.
As for the Skyraider's Mig victims, they should go punch their intelligence officer in the nose for not warning them of the rattlesnake nature of their opponent. "Know thine enemy!"
Cheers,
Wes

Punching political officers (probably the same one as the intelligence officer) in the nose is probably a good idea, but also likely to be a career (or life) limiting move. Any fighter pilot should know that a swept-wing jet will not be able to hang with a straight-wing prop, regardless of what the intelligence officer is or isn't saying. Trying to hang with a Gladiator in a FW190 would be a similar error in judgement.