Something I would like to ask real WW2 fighter pilots

[Charley]

Since becoming interested in flight sims, one thing I have noticed is that fighter combat in sims usually starts or quickly descends to low altitudes (1000 - 5000 ft). This seems to happen so naturally & easily. What I'm curious about is whether this was also true in real life WW2.

There's a couple of things I would like to ask the real life guys, if I could:

 

When I fly in a P51 (in sim ) at an altitude of 28 - 30,000ft, I feel like it's an effort to keep my plane flying stable & stay in nice formation., let alone maneuver. The controls become very mushy at altitude. My question is: How could these planes be effective in a dogfight at this altitude with such mushy control?

Another question is: Did the combat usually descend to such low altitudes in real life? If it did, were the escorted bombers abandoned while the fighters descended in combat?

If the fighter was a plane designed for best performance at high altitude , such as the P 47 or P 51, did they have strict orders not to pursue below a certain altitude, or to simply stay with the bombers ?

These are things I've wondered about, the main question being : how could anybody effectively dogfight at high altitudes, when it seems like the plane wants to flop around like a fish?

[Flagrum]

Since becoming interested in flight sims, one thing I have noticed is that fighter combat in sims usually starts or quickly descends to low altitudes (1000 - 5000 ft). This seems to happen so naturally & easily. What I'm curious about is whether this was also true in real life WW2.

I would expect that it was that way in reality as well.

 

When dogfighting, you try to maneuvre your aircraft into a position that allows you to kill the enemy. But your opponent does the same. That means, time is cruical - the one who gets quicker behind the other will win the fight. Now you have altitude as form of potential energy at your disposal. With this energy you can maneuver more agressively and generally be faster.

 

Of course it "all depends" - on pilot skill, simple (bad) luck, etc. - and you want to preserve that potential energy if possible, to make use of it in the right moment, but the tendency that the fight descends to lower altitudes seems only natural to me.

[zxarkov]

I have read a lot of pilot autobiographies and stories from air combat. I also have seen Bud Anderson talk at EAA for several years as well.

 

Sustained dog fighting is somewhat rare, usually the pilot that gets shot down doesn't even see the person who did it. In sustained fights it isn't uncommon for the fight to be dragged down to lower altitudes..

 

EAA is this coming week in Oshkosh,WI, I need to think of a good question for Bud Anderson if he is there this year.

[Rangi]

Yes quite often they did go low, you can read some of these combat reports and see what happened.

http://www.wwiiaircraftperformance.org/p-47/p-47-encounter-reports.html

After the 8th air force had a regime change and they started going after the German fighters to shoot them down, many dogfights would end up with the escorts chasing the German attackers to the deck.

[Oydoron]

Another question is: Did the combat usually descend to such low altitudes in real life? If it did, were the escorted bombers abandoned while the fighters descended in combat?

 

When the bomber mafia was in charge, allied fighters did not descend below a certain altitude to engage. When Doolittle took over, the new goal was to destroy the Luftwaffe. They descended, they chased, they searched, etc:

 

[Youtube]TmzzuMzOcKM

 

Start at about 27 minutes. Well, you probably want to watch the whole thing anyway.

[Rangi]

^very interesting video, thanks.

[Solty]

Since becoming interested in flight sims, one thing I have noticed is that fighter combat in sims usually starts or quickly descends to low altitudes (1000 - 5000 ft). This seems to happen so naturally & easily. What I'm curious about is whether this was also true in real life WW2.

There's a couple of things I would like to ask the real life guys, if I could:

 

When I fly in a P51 (in sim ) at an altitude of 28 - 30,000ft, I feel like it's an effort to keep my plane flying stable & stay in nice formation., let alone maneuver. The controls become very mushy at altitude. My question is: How could these planes be effective in a dogfight at this altitude with such mushy control?

Another question is: Did the combat usually descend to such low altitudes in real life? If it did, were the escorted bombers abandoned while the fighters descended in combat?

If the fighter was a plane designed for best performance at high altitude , such as the P 47 or P 51, did they have strict orders not to pursue below a certain altitude, or to simply stay with the bombers ?

These are things I've wondered about, the main question being : how could anybody effectively dogfight at high altitudes, when it seems like the plane wants to flop around like a fish?

Low altitude fighting was a domain of Eastern Front, where Soviet Fighters were usually supporting low level IL2 Sturmovik attacker planes, and Germans were supporting Ju87s. Usually German bombers neven flew very high too. (up to 3000m)

 

 

Depending on an airplane, advantages at different altitudes are different. Fights on the Western Front were done at 30.000ft and above and below of course, as P-47s and P-51s had to escort B17 and B-24 bombers. Bud Anderson had a dogfight at 30.000-29.000 ft in his P-51B vs Bf109G6.

 

Reconstruction of this dogfight was made by Hchannel and is a little bit hollywoody, but for a low budget show its quite well made, with a few simplifications.

 

Edited July 18, 2015 by Solty

[Hummingbird]

As Solty pointed out on the western front the fighting usually took place at high altitude as the Allied escorting fighters had to protect the bombers from the LW interceptors who were focused on hitting the bombers and then quickly getting their heavily armed aircraft out of dodge before the escorts would engage them.

 

The few times the Allied escort fighters ended up fighting clean LW fighters meant for protecting the interceptors the fights often dragged out however, and it was usually these who accounted for escort losses. Later on the Allied escorts were let loose and started hunting down and ambushing the LW aircraft at their own bases, and this is when the tide really turned. The LW simply couldn't put up enough aircraft enough of the time to maintain any form of numerical parity, usually being outnumbered many times to one - and when they did manage to put up a large force the majority of the pilots were rookies with very little training. It really was a lost fight from the beginning, the only aircraft with any hope of turning the tide was the Me262, but it quite simply arrived too late, with too few experienced pilots and was mercilessly hunted down at its own airfields when taking off or landing.

Edited July 18, 2015 by Hummingbird

[JST]

A good thing to keep in mind is that a common altitude for bombers was around 25,000ft and below, above less so, especially 30,000ft and beyond.

Edited July 18, 2015 by JST

[Solty]

A good thing to keep in mind is that a common altitude for bombers was around 25,000ft and below, above less so, especially 30,000ft and beyond.

But that was where Allied escorts and German "escort" for other interceptors. Fw190A groups usually were hitting the front of the formation at lets say 25.000ft and Bf109G formations flew at 31,000ft and were ready to attack P-51 and P-47 escorts. Many allied fighter pilots reported that usually Germans had altitude advantage when begining the fight.

Edited July 18, 2015 by Solty

[zantron]

thats the impression i get from reading books and comments i hear on youtube and tv.

 

nonetheless it would usually go low no matter what on the return trip, the p-51s would go down to strafe anything that looked interesting if they hadn't already expended ammo (my grandmother remembered this particularly when they were retreating with the german army in austria while in route to bavaria, they were on the train and the alert would come and everyone would jump off running for their lives as american planes, probably p-51s, would strafe the train. this happened quite a few times in her journey, they had a special nickname for the attackers i wish i could remember it)

 

i heard a tuskagee airman speak and if i remembered right they were at around 8-10k ft and they ended up really low when he got shot down, but the wiki article says it seems he was on a ground attack mission so i guess my memory isn't correct https://en.wikipedia.org/wiki/Alexander_Jefferson

Edited July 18, 2015 by zantron
typo

[Charley]

These are really good links from Rangi & Oydoron. Thanks! Unfortunately, I couldn't get the one from Solty, it's blocked in The U. S. for some copyright reason. That one I really wish I could also see because it would describe maneuvering at the altitudes I find so extremely mushy on the controls.

I'm working my way through the encounter reports for the P 47, but wonder a few things. I read the book "Thunderbolt" by Robert Johnson ( it turned me into a Thunderbolt pilot in my imagination), and remember that he made the comment about one dogfight that he looked at his altimeter and it "showed a height of 20,000 ft. -- according to all the rules, absolute suicide for the P 47". It seems like it would be really hard not to find yourself getting below 20, 000 ft. though. Also, if you did go down close to the deck, it's hard to get back up there to bomber altitude.

I'm still trying to learn more about how these real life guys handled different situations. When they didn't have the altitude advantage, did they always dive away? If they were assigned as escort , did they still dive away?

Anyway, I think these guys really did maneuver at very high altitudes & also took their planes ( even the P 47), down to lower altitudes , I just don't have the hang of it yet. I also wonder, because it feels so different, if many other people have tried maneuvering their DCS WW2 planes at altitudes greater than 20,000 ft.

Edited July 18, 2015 by Charley

[Oydoron]

Anyway, I think these guys really did maneuver at very high altitudes & also took their planes ( even the P 47), down to lower altitudes , I just don't have the hang of it yet. I also wonder, because it feels so different, if many other people have tried maneuvering their DCS WW2 planes at altitudes greater than 20,000 ft.

 

Flying at high altitude is pretty much identical to flying at low speed and low altitude. The higher you go, the more engine power you need for the same IAS, and thus as you go higher and higher, you'll end up flying with a greater and greater angle of attack. When up at high altitude, take a look at your IAS and then use the map to look at your true airspeed.

[Echo38]

and thus as you go higher and higher, you'll end up flying with a greater and greater angle of attack.

 

Hmmm--that doesn't sound right to me. TAS is higher up there, so turn circles are wider for a given IAS, and a wider turning circle means a lower AoA, not higher. On the flip side, if you can pull the same AoA at a higher TAS, you're pulling more G's.

 

Further corrections welcome--I'm not an engineer, I'm afraid.

[Anatoli-Kagari9]

- Intentionally left blank -

Edited August 17, 2015 by jcomm

[Oydoron]

Hmmm--that doesn't sound right to me. TAS is higher up there, so turn circles are wider for a given IAS, and a wider turning circle means a lower AoA, not higher. On the flip side, if you can pull the same AoA at a higher TAS, you're pulling more G's.

 

Further corrections welcome--I'm not an engineer, I'm afraid.

 

A very basic explanation is that lift is calculated examining how much air is hitting the wing at what speed, and what the AOA is.

 

- You go twice as fast, you hit twice as much air.

- Air density decreases and there is half as much of it, you hit half as much air.

- To balance the two, you need to go twice as fast (TAS).

 

This again, a simplification, but your IAS is really just a measure of how much air your aircraft is hitting. So whatever your altitude, temperature, air density, etc, if it says 250km/h IAS, you always need the same angle of attack to maintain level flight. Incidentally, you are also experiencing the same amount of drag, but are going much faster. Yay fuel efficiency.

 

Turning circles are wider because you've scaled everything with air density. You still need the same amount of air to pull a 2g turn, you just have to cover a lot more ground to get it. I'm pretty sure your turn rate in degrees/sec, AOA, and g-load will be the same given the same IAS. You can calculate the circumference by multiplying your TAS by 360/turn rate, and then radius by dividing by 2pi. (Or vice versa to get the turn rate)

 

Once you add power, you run into two problems. The first is that there is less air for the engine to work with, so you burn less fuel and get less power. A problem battled with supercharger stages. The second is the faster air that was working for you on your wing is working against you on your prop. To push as much air, the prop must spin twice as fast. On one hand, it's still pushing with the same force as before, just like the wings. But on the other hand, power is force * distance, and the prop is covering twice as much distance with the same force, so it needs twice as much power.

 

So you end up needing twice the power to go twice as fast (TAS). Normally, the power/speed ration follows a cube law, so a square law is quite the savings. This can also be explained in that the most efficient speed for a plane is usually not too far from stall speed with a high AOA. When you fly at low altitude, it might be fuel efficient, but it's super slow. At high altitude, you are actually booking it at this high AOA configuration. Once you go high enough, your IAS approaches stall speed and your vertical indicator starts pointing down. If you try to correct for it, you'll stall and need quite a bit of altitude to recover.

 

If you compare the Ta-152 and the Dora, the Ta-152 has much more wing surface, which gives it a lower stall speed, and a bigger engine to give it more power at altitude.

[Echo38]

the most efficient speed for a plane is usually not too far from stall speed with a high AOA. When you fly at low altitude, it might be fuel efficient, but it's super slow. At high altitude, you are actually booking it at this high AOA configuration.

 

Ah, yes. Straight & level, you'll have higher AoA up there. [nod] Hence the eventual ceiling. But in turns ... hmmm. I think I see what you're getting at. Tough question!

 

TAS doesn't actually increase necessarily. IAS does decrease, and the "lighter" air calls for additional AoA, hence, induced drag, etc...

 

Well, I mean with WWII fighters, specifically. Most of them fly faster at altitude than they do on the deck, with the max speed being achieved the altitude, determined by the supercharger. E.g. angels 20-something for the P-38's turbosupercharger (IIRC). So, comparing a P-38 at 5000 feet to one at 25000 feet, the TAS is quite a bit higher for the latter.

 

Also, according to a chart in the P-38 operating handbook, the best climb IAS decreases with altitude, despite the true airspeed being higher. Which gives me some confusion as to what exactly happens to the turns. A higher best climb IAS will mean a higher sustained turn IAS speed, too, right? Hrm. I'm out of my element--I guess I really don't know what that'll do to AoA & turn radius&rate & G-load.

[Oydoron]

Also, according to a chart in the P-38 operating handbook, the best climb IAS decreases with altitude, despite the true airspeed being higher.

 

Might this be to a reduced amount of power being available?

 

 

Which gives me some confusion as to what exactly happens to the turns. A higher best climb IAS will mean a higher sustained turn IAS speed, too, right? Hrm. I'm out of my element--I guess I really don't know what that'll do to AoA & turn radius&rate & G-load.

 

For sure, if you don't have as much power, you can't sustain the same turn. As far as turns you can sustain, I'm fairly certain that if you have the same IAS, same bank angle, and same AoA, you'll get the same turn rate in degrees/sec and same g-load. The turn radius will be much larger. I haven't found verification yet.

[Charley]

I don't know what real test figures would prove about turn rate ( I feel proud if I can convert IAS to TAS), but to me, it feels like the turn radius is greatly increased while the turn rate is decreased. Maybe the turn rate feels like it is reduced because I have to be ever so careful to be sensitive with the controls so I don't over control.

This brings up another slightly confusing thing for me. The DCS P 51 manual says :

"As a general rule, the greater the altitude, the greater the control movement required to achieve the same response. "

I find just the opposite to be true in the sim. It seems much more sensitive to control input at altitude.

I also found this in a Boeing document about high altitude maneuvering that seems to contradict the DCS manual: http://www.boeing.com/commercial/aeromagazine/aero_02/textonly/fo01txt.html

" For example, for the same control surface movement at constant airspeed, an airplane at 35,000 ft (10,670 m) experiences a higher pitch rate than an airplane at 5,000 ft (1,524 m) because there is less aerodynamic damping. The pitch rate is higher, but the resulting change in flight path is not. Therefore, the change in angle of attack is greater, creating more lift and more g. If the control system is designed to provide a fixed ratio of control column force to elevator deflection, it will take less column force to generate the same g as altitude increases. " This seems to confirm that it's accurate that control surfaces should be much more sensitive at altitude.

In the end though, I'm still amazed that they could successfully maneuver in dogfighting at 25- 30,000 ft.

Edited July 19, 2015 by Charley

[Echo38]

In the end though, I'm still amazed that they could successfully maneuver in dogfighting at 25- 30,000 ft.

 

For an experienced pilot, energy fighting is easier up there, because you've got more to work with. The TAS is higher; there's more E. So, for example, you can zoom out of gun-range quicker up there, than you can down low. The turn&burners struggle more at that altitude, and so the energy fighters dominate more than they do at low altitudes.

 

For a less-experienced pilot, it can be pretty daunting, because you are closer to stalling at any given point, all else equal. Closure rates show that the speeds are high, but the IAS is low and (if you don't have a visual reference point, e.g. your opponent) your aircraft feels like it's going slow. But with a bit of practice, one can get to the point where you're more comfortable up there than down low. I know I am (or was, back when I was doing it regularly).

 

Another thing to note: it's easier to maintain your total E state up there than down low, in most of these birds, because of the supercharger thing. So, at angels ten, a P-38 will struggle more to keep her altitude in a dogfight, than a P-38 at 25000 feet. The tendency of fights to lower in altitude is less pronounced, the closer you are to your aircraft's optimal altitude.

[Oydoron]

For example, for the same control surface movement at constant airspeed, an airplane at 35,000 ft (10,670 m) experiences a higher pitch rate than an airplane at 5,000 ft (1,524 m) because there is less aerodynamic damping.

 

Right, the same reason that the prop has to spin faster gives you greater roll (and pitch) rate. Your roll rate is limited by the wings having to push a crap load of air out of the way. When there is less air that needs to be pushed out of the way, you can roll faster. But at the same time, your IAS is limited at altitude, and a lower IAS gives you less control authority. But at the same IAS, the control authority should be similar.

 

If you want to test control responsiveness, fly at sea level at a given IAS in level flight, then try the same thing at high altitude. Note that if you gain or lose altitude during your maneuvers, other factors will probably change things around a bit. I think gaining TAS is quicker at high altitude, but gaining IAS takes longer.

 

I've rethought the turn rate thing by imagining two aircraft on a turn table, one far out, one close in. Both are turning at the same turn rate, but the one further out must have higher loading.