Guide to calculating turn rates of aircraft (1 Viewer)

Stig1207 said:

Claimed or was credited with that number of kills, but was that what the Japanese lost in those encounters?

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Swede Vejtasa - Wikipedia

I'm not sure if anyone has ever tried to connect his confirmed aerial victories to actual Japanese losses however.

ODonovan said:

I see a lot regarding sustained turns and initial 360 turns, but I see nothing about turns which were not circular. I doubt many pilots did circular 360s, at least after the first few seconds. That's been my experience in simming, anyway. It would be "pull it in tight, lose some speed, relax the turn to gain back a bit of speed, then pull it in tight again," so most sustained turns would be more like a series of ovals.

For pure turning, even the Dauntless could out-turn the Zero in a dogfight simply because the Zero couldn't go above six Gs without ripping the wings off and the Dauntless could go as high as 12 Gs. Once the Dauntless pulled a firing solution on the zero, the pilot could take a shot then relax his turn to conserve speed and altitude, knowing the Zero didn't have that powerful of an engine and would have to swing a bit wide to keep E as well.

Before I get tons of "you have to be kidding" responses, this actually happened in real life.


"Swede" Vejtasa was a true badazz pilot. All I know is that I wouldn't have wanted to have been his gunner, that day. When they landed, he was probably three inches shorter in height than he was when they took off. The Navy (in effect) said to Vejtasa, "if you're such a hotshot in a Dauntless, let's see what you can do in a fighter," so they transferred him into Wildcats. He proceeded to get seven kills in one day, and that was in a Wildcat, not even a Hellcat. Bad to da bone!



-Irish

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Hello ODonovan,
Sometimes Simulators can teach a few things. There are a bunch of other things to try if you find very quickly that you can't turn with your target. It would be kinda stupid to keep trying the turning fight if you see in the first few seconds that it isn't working.
One of the other effects of loosening up the turn for a few seconds would be that you offset your turning circles and turn radius becomes less important.

The A6M fighter was stressed for quite a bit higher than 6G though probably not quite as much as the Dauntless. This was covered in another thread not long ago and can be found in Horikoshi's book Eagles of Mitsubishi.
No question that Vejtasa was THE fighter pilot that day, but be very careful about relying on those videos for accurate information.
Two details (that I noticed) are incorrect in the video. At the time, the model of Type Zero fighter that was in service was actually the A6M2 and the comment that the 20 mm cannon on the Zero outranged the .50 Cal on the Dauntless was incorrect.

- Ivan.

DarrenW said:

Swede Vejtasa - Wikipedia

I'm not sure if anyone has ever tried to connect his confirmed aerial victories to actual Japanese losses however.

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Lundstrom may have, and according to him 'no (Japanese) fighters were lost in this combat', referring to May 8 '42.

Lt Stanley W. ""Swede" Vejtasa SBD victories | US-AIRCRAFT.COM History-Modeling-Forum

I have an issue with these calculations in principle. They may well give a pilot an indication of his planes performance in one aspect of performance, but it is one planar aspect. Discussion of a planes turning radius at a particular altitude and speed ignores the reality that a pilot must make the conscious choice to maintain that height and speed, the data from these tests must be very useful to a pilot as background "numbers" to be considered along with all the other myriad numbers concerned with flying a plane. Planes have a turning rate, a climb and dive rate and a roll rate which all have values which vary with many things like altitude and temperature. However the values for turn rate at sea level, where this type of conflict frequently ended are always theoretical, the men that passed the limit died.

A turning conflict at one altitude is a laboratory experiment which yields some information. In practice, pilots, if they had any sense at all turned, rolled and dived or climbed all in the same manoeuvre or series of manoeuvres. I have no idea whether experiments were done measuring roll rate while turning or climbing/diving, I suspect not but I also suspect pilots built up a mental picture of what could and couldn't be achieved in their mental archive of "numbers".

I raced an X7 Suzuki against RD250LC Yamahas, the Yamaha was faster, slightly, on top speed, much quicker on acceleration from medium speed corners and much, much more stable in fast corners. However the Suzuki was better at braking deep into a corner, quicker through a corner and in a different league when switching from one corner to another. I cannot quote any values for any of this, it is purely what I saw and felt, and it it is only relative. Maybe some pilot can tell me if its possible for a plane to be good at roll and at turn but not at both roll and turn at the same time?

The A6M was not stressed for more than 6G. It was stressed for exactly 6G with a 100% safety factor. U.S. fighters were stressed for 8G with a 50% safety factor. There is a difference in these ratings.

That means they BOTH start to fail at 12G, but the U.S. fighter can take 8G with no damage.

Anything above 6G in an A6M starts to cause g-damage. Sure, it can TAKE some g-damage, but g-damage is cumulative and it will fail at elevated g-levels before a U.S. fighter will. Not sure that matters much in a WWII dogfight where nothing could regularly sustain that much g-force, but a panic pull in a dogfight to escape death might see the difference start to surface, especially after some repeated over-g flights.

That even caught the F-15 once and one of them came apart in ACM maneuvering. The particular aircraft involved had sustained repeated over-g flights, and was continually cleared for normal flight after same. I never DID hear the end result of all that. I'm pretty sure Biff knows, though.

GregP said:

The A6M was not stressed for more than 6G. It was stressed for exactly 6G with a 100% safety factor. U.S. fighters were stressed for 8G with a 50% safety factor. There is a difference in these ratings.

That means they BOTH start to fail at 12G, but the U.S. fighter can take 8G with no damage.

Anything above 6G in an A6M starts to cause g-damage. Sure, it can TAKE some g-damage, but g-damage is cumulative and it will fail at elevated g-levels before a U.S. fighter will. Not sure that matters much in a WWII dogfight where nothing could regularly sustain that much g-force, but a panic pull in a dogfight to escape death might see the difference start to surface, especially after some repeated over-g flights.

That even caught the F-15 once and one of them came apart in ACM maneuvering. The particular aircraft involved had sustained repeated over-g flights, and was continually cleared for normal flight after same. I never DID hear the end result of all that. I'm pretty sure Biff knows, though.

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Hello GregP,
I understand the difference. My reference for this statement was the book "Eagles of Mitsubishi".
Your statements are a bit more consistent what I actually believe from anecdotal evidence, but what is the actual source?
I know I have seen this in literature but can't recall where.
I know you have access to an actual aeroplane, but presumably you are not attempting to test it to destruction.

Please take a look at the discussion in this thread:
Performance difference between the A6M5a and A6M5b/c

You were in the discussion early on, but I don't know if you continued to follow it.

Thanks.
- Ivan.

Actual source is the original designer and the design documents we have. Jiro Horikoshi helped the Planes of Fame (The Air Museum at the time) restore our A6M5 Model 52 in 1976 - 1977 timeframe. We also have some original design documents, plus all the notes we have from his time in Chino. You are right, we do NOT test anything to destruction in the air or on the ground. The intent is preservation, not more restoration.

I have never seen, "Eagle of Mitsubishi," and would love to.

I have a mountain of pics where we did a major overhaul a few years ago when we had it down to bare aluminum with EVERYTHING removed for overhaul. It got new cables, new primer, paint, and a lot of little repairs / updates to things that happened over the years. We are asked not to post any of the pics on the internet by the museum, but I can tell you the A6M5 Model 52 is well-built with workmansip similar to U.S. fighters of the day. They did things we would NOT do, but they did them well most of the time. I can get any pics desired of the outside of the Zero, but am asked not to share any cockpit pics or pics of things in work during restoration. Attached is a pic of our J2M Raiden. Even though the nose is a bit dark, it shows the exterior of the aircraft from a view anyone could get, so it is OK to show in here. I also attached a pic of the Zero just before it's first post-overhaul test flight.




I didn't continue to follow that thread you posted above because we seem to pursue a lot of things down to the smallest detail, usually way past my interest level. When I look at original documents, most of those details do not exist. I'll discuss to the last detail, but have no interest in arguments about anything. The difference is one way, you talk about the data and the aircraft and the other way it gets personal. I also have less time for it than I used to have, even though the interest is still there.

Cheers.

GregP said:

The A6M was not stressed for more than 6G. It was stressed for exactly 6G with a 100% safety factor. U.S. fighters were stressed for 8G with a 50% safety factor. There is a difference in these ratings.

That means they BOTH start to fail at 12G, but the U.S. fighter can take 8G with no damage.

Anything above 6G in an A6M starts to cause g-damage. Sure, it can TAKE some g-damage, but g-damage is cumulative and it will fail at elevated g-levels before a U.S. fighter will. Not sure that matters much in a WWII dogfight where nothing could regularly sustain that much g-force, but a panic pull in a dogfight to escape death might see the difference start to surface, especially after some repeated over-g flights.

That even caught the F-15 once and one of them came apart in ACM maneuvering. The particular aircraft involved had sustained repeated over-g flights, and was continually cleared for normal flight after same. I never DID hear the end result of all that. I'm pretty sure Biff knows, though.

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Greg,

The MOGUARD Eagle that broke up in flight was one of the top 5 or 10 most over G'd Eagles in the USAF. The design was changed starting with the E model. The part that failed was, if I remember correctly, called a longeron, and the top of it is what the bottom of the canopy sits against. There were several different variations of that part (vendors?) which in the end IIRC didn't matter. There were fatigue cracks which propagated over time into structural failure.

I do know of several instances where an Eagle was over G'd to the tune of 11+ and flew again. I know of smaller over G's that resulted in wing changes. Needless to say if you are about to hit the ground, something attached to it, or something that took off or will land on it, pull as required to your limits or the jets (whichever comes first).

Regardless that the name on the data plate says MacAir, I think they had help from Mack and Tonka. One shot down a Flogger in Desert Storm after losing a wing tip during jettison of its wing tanks. Another landed missing it's entire right wing. I've done a 2 G turn at 43k and 1.3 Mach with three external tanks, 8 missiles, and a loaded gun. I know multiple guys who have been above 70k in one while still climbing. I can relate to those guys from WW2 who loved their planes and felt damn near invincible in it. You don't strap in as much as you strap it on. I had total confidence in it whether over friendly terrain or in Indian country.

Cheers,
Biff

Hi Biff,

Appreciate the reply. I knew the over-g'd Eagle had a cracked longeron, and if you can FIND all the cracks, you can replace the components and return even a damaged aircraft to service status. At Fighter Rebuilders, they have removed the entire tail of a P-51, replace cracked bulkheads, reattached the tail, and returned it to flight status.

You could do the same for an Eagle, if it were rare enough to warrant that attention and expense. After they are out of service and flying in private hands, they might BE that valuable to the operator. When there are excess Eagles, maybe not to the government.

Personally, I'd LOVE to see an F-15 airframe, updated with modern avionics, with a slight redesign to address any flight characteristics that need "updating." I understand that an F-15 will not quite roll, turn, or climb with 5th-generation jets (could be wrong?). But it is definite a solid airframe that could be updated, if we weren't so militarily obsessed with stealth.

I'm not sold on stealth because it can be defeated by changing frequencies and by various other means. Once stealth is gone, you have spent a LOT of money for nothing and you fall back on airframe performance and good avionics ... enter the updated Eagle.

Cheers!

Actually, Biff, answering this reminded me that I was supposed to send you a CD of pics. I may have time to get that done a couple of years late. Somebody slap me, and don't everyone volunteer all at once ...

If I remember my aerostructures nomenclature correctly, the design load, say 6 g, means there is no plastic deformation. Anything past that may have permanent deformation until the ultimate load factor is reached, when catastrophic failure is possible.

swampyankee said:

If I remember my aerostructures nomenclature correctly, the design load, say 6 g, means there is no plastic deformation. Anything past that may have permanent deformation until the ultimate load factor is reached, when catastrophic failure is possible.

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That is Correct to US Military Design Sds. The Limit Load is approximate to the transition from elastic to plastic deformation - at the Specific Design Gross Weight. The 'original P-51/NA -73/Mustang I was stressed for 8G at 8000 pounds gross weight. The Limit Load in succeeding airframes was reduced accordingly as Gross Weight climbed from 8000 to 10,200 at the P-51D/K. The first re-design change was the XP-51F/G/J and finally the H in which the new limit Load was 7.3G at 9600 (P-51H) and Ultimate was a factor of 1.5= 11G at 9600.

Hello GregP,
In your discussions with Mr. Horikoshi, did he explain whether the 6G limit was for the original A6M1 / A6M2 or was it for the A6M5 that you were restoring at the museum? There was a bit of weight added between the different versions.

- Ivan.

Hi Ivan,

Mr. Horikoshi was at the museum in a mid-1970s timeframe and I was not anywhere near California at the time. I started volunteering in 2006. I have heard the design spec, but it never occurred to me to ask whether or not it was for the A6M5 because the A6M6 Model 52 is the only airfame we had at the time (at still have), and I assumed (and still do) the discussions were about our particular aircraft.

If I think of it when Steve Hinton is around, I'll ask, but the A6M5 Model 52 had heavier-gauge wings than the earlier A6M variants, and I have never heard of any limits that were less than the earlier variant anywhere, from any source, or even suggested. The A6M5 extended the dive speed as well as controlability at higher speeds. Steve has been gone to airshows recently.