Low-level speed of Cold War aircraft

[Rob de Bie]

On 9/18/2020 at 3:22 PM, Antti_K said:

Hello Rob and all,

 

when you enter the subsonic air speed region where the drag starts to increase rapidly the aircraft's nose rises slightly and starts to wander from side to side. Due to it's hydraulic controls Draken is an unpleasant aircraft to steer at these speeds as you have to make two control inputs: one to correct the attitude and a second one to counter-act the first one. This requires full concentration on the job and is therefore rather exhausting. And still the flight isn't exactly straight and level. At high speeds there was also a risk of servo stall.

 

Thanks Antti for the details! Interesting flight control aspects that I had never read before. Can you tell more about the servo stall? Was the hydraulic actuator not strong enough at high q ?

 

Rob

Edited September 19, 2020 by Rob de Bie

[JayBee]

Maybe an interesting Luftwaffe Alpha Jet video (if you understand German) about low flying and what is possible (or not):

 

https://www.youtube.com/watch?v=N0Ynlg8bc_4

 

 

[Rob de Bie]

23 hours ago, Aardvark said:

There is something else, there were serious local problems with aerodynamics, which seemed to be realized when the plane had already started to enter service.  More details here:
https://afirsov.livejournal.com/485629.html
https://afirsov.livejournal.com/508033.html
about transonic modes, it is very interesting written here in the comments:
https://afirsov.livejournal.com/402091.html

Serge, thanks for the links. It's very interesting reading, although the translation makes me understand only about half. I never thought about Karman street vortices developing on the sides of a slender fuselage (like the F-104), or the yawing effect of an asymmetric pitot tube mounting (Su 17). But I never ever heard any 104 pilot talking about a yawing problem. I will ask around. But at least I now have a clue about that oscilating yawing behaviour of some fighters.

 

It was also very, very interesting to see judgement passed on US / Euro fighters from the Russian / Soviet side. Like the speed performance of the F-104 and MiG-25 flying parallel on each side of the border 🙂 And the comment on the wrong shape of the 104's horizontal tail. Thanks again!

 

Rob

[Aardvark]

56 minutes ago, Rob de Bie said:

But I never ever heard any 104 pilot talking about a yawing problem. .

But a very interesting nuance is written there, the problem arises to a greater extent with a combination of two factors - good surface treatment and high qualification of the pilot!  With the surface, Starfighter was doing well, and about the high qualifications of the pilot, it is explained that the more precession and accurately he pilots the plane, the higher the likelihood of this effect!  Such is the paradox.

56 minutes ago, Rob de Bie said:

But at least I now have a clue about that oscilating yawing behaviour of some fighters.

This will be interesting!

56 minutes ago, Rob de Bie said:

It was also very, very interesting to see judgement passed on US / Euro fighters from the Russian / Soviet side.

Some clarification is needed here.  I don't remember exactly, but A. Firsov is now more of an aviation historian and journalist, possibly having access to the archives of TsAGI and probably studying at the Moscow Aviation Institute, but his opponent known as "Fan-de-Or", in his words, worked in the MiG design bureau in the direction of  aerodynamics are now probably retired.

56 minutes ago, Rob de Bie said:

Like the speed performance of the F-104 and MiG-25 flying parallel on each side of the border 🙂

Yes, somehow unexpectedly ... but this is the opinion of only one unknown pilot (on the Internet), which is very much beyond the generally accepted concepts and documents.

But at the same time, it is indicated that the F-104 had only two AIM-9 and the MiG-25 had all 4 not little missiles.

56 minutes ago, Rob de Bie said:

And the comment on the wrong shape of the 104's horizontal tail.

But at the same time, Eger is the author of the Tu-154 scheme, which is almost impossible for a pilot without special training to get out of the spin, although an experienced test pilot Scherbakov , the main specialist in spin in the USSR, successfuly took the Tu-154 out of the spin.

And to be completely objective, we can recall the wing of the MiG-23 and its aerodynamics, which only in the modification of the MLD became a serious weapon.  True, the academician Bushgens was engaged in aerodynamics, the wing was altered three times ...

so the USSR, despite its advanced school of aerodynamics, had its own epic fail...

 

B.R.

Serge

Edited September 19, 2020 by Aardvark

[Rob de Bie]

13 hours ago, Aardvark said:

But at the same time, Eger is the author of the Tu-154 scheme, which is almost impossible for a pilot without special training to get out of the spin, although an experienced test pilot Scherbakov , the main specialist in spin in the USSR, successfuly took the Tu-154 out of the spin.

And to be completely objective, we can recall the wing of the MiG-23 and its aerodynamics, which only in the modification of the MLD became a serious weapon.  True, the academician Bushgens was engaged in aerodynamics, the wing was altered three times ...

so the USSR, despite its advanced school of aerodynamics, had its own epic fail...

I've long accepted that nothing is as perfect as one would wish, it's always a compromise. So there will be faults and shortcomings everywhere.

 

If the website that you linked to has something on the aerodynamic problems of the MiG-23, I would love to read more! I also understood that the MLD was excellent, but all earlier versions were sort of nasty 🙂

 

Spinning with a Tu-154 ?? I don't think that was *ever* intentionally done with western equivalents.. It reminds me of a story in Ed Heinemann's autobiography, in which he describes how a Dutch delegation came to test a certain Douglas aircraft under development (forgot which) and insisted to spin-test it. But Douglas had never spun it, it was too big to risk that, and there was no requirement for it. The delegation went out and spun it nevertheless, leaving quite an impression on the test team.

Rob

[Hook]

17 hours ago, Aardvark said:

And to be completely objective, we can recall the wing of the MiG-23 and its aerodynamics, which only in the modification of the MLD became a serious weapon.  True, the academician Bushgens was engaged in aerodynamics, the wing was altered three times ...

To be fair, this was as much because of changing tactical requirements - close in dogfighting was not really considered when the MiG-23 concept was developed. It was meant to have a short takeoff run, carry more AAMs further than the MiG-21 and lob them at the opposing side at high speeds. 

 

Of course, then close in combat came back in fashion post-Vietnam... 

 

Cheers,

 

Andre

[Aardvark]

7 hours ago, Rob de Bie said:

If the website that you linked to has something on the aerodynamic problems of the MiG-23, I would love to read more! I also understood that the MLD was excellent, but all earlier versions were sort of nasty 🙂

No, in the Live Journal following the link I gave, I do not remember the description of the problems with the MiG-23, I read about the problems here:

and probably I quoted this book on BM, don't remember where.

But I remember exactly that in the LJ there is a description of the problems with the Mirage and F-86/100.

There turned out to be a rather funny situation in the battles of the MiG-21 with Mirages.  The problem is that when fighting on bends, on the MiG-21, the shaking began earlier than on the Mirage, but the breakdown of the MiG-21 came later than that of the Mirage.

Those,  the MiG-21 was shaking, but it still flew and broke down later than the Mirage.  But the amusingness of the situation is that this knowledge is post facto and the initial recommendations were to refrain from fights for a turn with the Mirage.

In the LJ indicated by me, there is an article explaining this from the point of view of the Mirage aerodynamic scheme.

8 hours ago, Rob de Bie said:

Spinning with a Tu-154 ?? I don't think that was *ever* intentionally done with western equivalents..

When it comes to saving the lives of passengers, then all methods should be considered...however, there are many complaints about the Tu-154 in particular, as well as the Tupolev in general.  It is believed that the competitor Tu-154 from Ilyushin was better, but Tupolev had more authority with the customer.

4 hours ago, Hook said:

To be fair, this was as much because of changing tactical requirements - close in dogfighting was not really considered when the MiG-23 concept was developed. It was meant to have a short takeoff run, carry more AAMs further than the MiG-21 and lob them at the opposing side at high speeds. 

Not really, two eternal problems of the USSR industry - engines and electronics, did their job, the plane became heavy and grew out of its wing.

The new wing was larger, but did not have slats, so there was a very dangerous swing during takeoff and landing. And already in the MLD version, having installed a new wing, a lighter and more economical engine, perfect and reliable electronics, reducing the weight by almost 1 ton, applying the achievements of vortex aerodynamics, they got an excellent fighter.

This is briefly.

 

B.R.

Serge

[Blacktjet]

On 8/17/2020 at 3:59 PM, Lord Riot said:

Actually I remember many years ago at Finningley airshow asking an American F-4 crew (can't remember if it was an RF-4C or F-4E) how fast it would go, and being slightly disappointed when they said 800mph. I was expecting 1,500 like in all the books! 😂

 

Similarly a Tornado crew told me "about 600mph", when I said I thought it was over 800 at low level they said "maybe a brand new one, with no underwing stores". So they lose engine power, like old cars?

I remember hearing a 43 sqn pilot requesting an a/c,

 

Cpl WAFF; "which one", 

PILOT; "One that can go supersonic"

 

I looked at the board and only 4 out of I think 12 avaliable were cleared to go supersonic - 1980/81 Phantoms 

[exdraken]

29 minutes ago, Blacktjet said:

I remember hearing a 43 sqn pilot requesting an a/c,

 

Cpl WAFF; "which one", 

PILOT; "One that can go supersonic"

 

I looked at the board and only 4 out of I think 12 avaliable were cleared to go supersonic - 1980/81 Phantoms 

but that was I guess a structural safety issue with the other 8, no? not the design capability

I'd assume in war they would have been able to go past M1..

 

[Aardvark]

19 minutes ago, exdraken said:

I'd assume in war they would have been able to go past M1..

On WWIII? If they could physically,

of course yes!  Because it was a one-way road ...I read somewhere that after equipping and refueling those returning from the first strike, ground personnel had to join the infantry units.  My late father-in-law, who served in tank units (and safely drowned a tank during an maneuvers 😁 T-62  or T-55 don't know), said that the lifetime of his tank regiment in World War III was estimated at 20 minutes of combined arms combat.

 

B.R.

Serge

[Lord Riot]

8 minutes ago, Aardvark said:

On WWIII? If they could physically,

of course yes!  Because it was a one-way road ...I read somewhere that after equipping and refueling those returning from the first strike, ground personnel had to join the infantry units.  My late father-in-law, who served in tank units (and safely drowned a tank during an maneuvers 😁 T-62  or T-55 don't know), said that the lifetime of his tank regiment in World War III was estimated at 20 minutes of combined arms combat.

 

B.R.

Serge

 

Scary times. I guess with NATO's 'Tripwire' policy in reality everyone's life expectancy would have been closer to three minutes!

[Aardvark]

On 9/20/2020 at 3:20 PM, Rob de Bie said:

If the website that you linked to has something on the aerodynamic problems of the MiG-23, I would love to read more!

In this book: 

""Fighter  MiG-23. On defense  the sky motherland"  / Viktor Markovskiy, Igor Prichodchenko - Moscow: Exmo: Yazuza, 2017"

( In general, as for my very good book! Recommend!) three(!) pages about problem with aerodynamic wing first MiG-23. I can place these three pages in the corrected automatic translation, in a separate topic, if it's interesting.

3 hours ago, Lord Riot said:

Scary times.

It's even worse now.  

Because then politicians and military still remembered what global world war was and understood

what will nuclear war lead to. 

Now era politicians and military  who don't know what global war is and

who do not understand what a real nuclear conflict is, confusing it with a computer game and who have only $, €, £, ¥, ₽ etc in their eyes...forgetting that their money is not accepted for payment in hell.

 

B.R.

Serge

 

 

[Rob de Bie]

14 hours ago, Aardvark said:

In this book: 

""Fighter  MiG-23. On defense  the sky motherland"  / Viktor Markovskiy, Igor Prichodchenko - Moscow: Exmo: Yazuza, 2017"

( In general, as for my very good book! Recommend!) three(!) pages about problem with aerodynamic wing first MiG-23. I can place these three pages in the corrected automatic translation, in a separate topic, if it's interesting.

 

Serge

 

 

 

Serge, thanks for the offer! Yes please, but only if it's not taking up too much of your time..

 

Rob

[Aardvark]

2 hours ago, Rob de Bie said:

Yes please,

Deal!

2 hours ago, Rob de Bie said:

but only if it's not taking up too much of your time..

The time spent on the forum is the time that I did not spend with the model, in my case it was the time not spent building the Mirage III V within the GB on the BM!😉

But on the other hand, the models are made for themselves, and what is written on the forum is done for others. 

Therefore, of course, I will publish this fragment in a separate topic, given the capabilities of modern automatic translation systems, this does not take much time.

 

But, return to main topic thematic!

Here is how the MiG-23 developers saw the advantages swept-wing

when flying at low altitudes

with a description of the problems that arise during such flights:

"Another advantage was the provision of good working conditions for wing mechanization - flaps and slats, the most effective just with a straight wing, which gave an additional gain in take-off and landing characteristics.  Folding the wing, on the contrary, helped to reduce the dependence of the aircraft on air turbulence - "air holes".  The latter was especially annoying at low altitudes, to the use of which military aviation began to switch to stealth and reduce vulnerability to air defense. Surface ascending and descending currents of disturbed air made the atmosphere so turbulent that for an airplane flying at speed (and especially its pilot), the flight resembled driving on a cobblestone  pavement with shaking, unfavorable both for the strength and performance of the machine, and for the pilot's endurance up to the impossibility of control over the control. With wing retraction, the span became smaller and, at the same time, the load on the wing increased, the aircraft was subjected to less disturbances and became less dependent on turbulence."

from:

18 hours ago, Aardvark said:

""Fighter  MiG-23. On defense  the sky motherland"  / Viktor Markovskiy, Igor Prichodchenko - Moscow: Exmo: Yazuza, 2017"

 

B.R.

Serge 

[Aardvark]

On 9/26/2020 at 2:21 PM, Rob de Bie said:

Yes please,

"All what You want"!(c) 

😁

Now everyone who wants to talk about Cold War aerodynamics can do it in a separate topic!

😎

B.R.

Serge

 

[RobertS]

On 16/08/2020 at 15:52, Doc72 said:

Hi everyone,

 

just out of curiosity (and to discuss nerdy aircraft stuff) I wondered how fast Cold War aircraft actually flew at low-level or would have flown in an actual mission.

Vietnam, May 10 1972 - low-level 'drag-race' MiG-21MF(?) vs F-4J, F-4D >

 

" Nearly out of missiles and starting to run short of fuel, the Phantoms went supersonic and sped toward the coast.

"At that time we had strong intelligence that the MiG-21 could not do more than Mach 1.05 below five thousand feet. We were doing Mach 1.15 in combat spread, feeling cocksure as we headed towards the coast."

Dosé recalled:

"Then a MiG-21 came up behind, overtaking fast. He made it look effortless. When I saw the MiG it was about three-quaters of a mile behind Hawkins. I called for an in-place turn, and as we began turning the MiG fired an Atoll missile at Hawkins. Initially it guided, but it couldn't handle the Gs and it wasn't ever a real threat."

After attacking the MiG broke away to the right. Instintictively Dosé turned after it, until McDevitt demanded incredulously, "What are you doing!" The back-seater's tone reminded Dosé that they had neither the missiles nor the fuel for another engagement. Chastened, the pilot reversed his turn and headed for the coast.

Almost certainly the MiG-21 that had caught up with the Phantoms was the new MF sub-type. It was the first time American crews had encountered this version, and its much improved low-altitude performance came as an unpleasant surprise. "

 

" As the survivors of Oyster Flight sped out of North Vietnam at low altitude, a MiG-21MF arrived to cause consternation for the second time that day. Oyster 2 ran out alone, 3 and 4 stayed together. Chuck DeBellevue, in Oyster 3, watched with disbelief as the Soviet-made fighter closing from behind seemed to join formation on the pair. "We were running out at seven hundred to seven hundred fifty knots(Mach 1.06 to 1.13), the F-4 wouldn"t go any faster that low. And we had a MiG-21 chasing us and keeping up-that surprised the hell out of us!" To DeBellevue, the MiG's ability to keep up was disconcerting, to Captain Larry Pettit in Oyster 4 it was terrifying: "He was at our eight-thirty position(left quarter), one hundred feet above and about three hundred feet out to the side. He caught up with us and was staying with us! I don't know if he saw us, but he had a gun and he could have strafed the s.it out of us." Larry Pettit's next move did nothing to lessen the danger but was understandable in the circumstances: "I lowered my seat to the floor, to hide from him! He banked towards us and I thought, Oh no, he's going to let us have it with cannon....But he turned and went off in the opposite direction, Tommy Feezel and I thanked our lucky stars and got the hell out of there."

 

Edited October 19, 2022 by RobertS

[Ossington 2]

I haven't read every note in this thread, so I might have missed it: What really happens when you drop bombs/tanks at these speeds? It is not unknown for ordnance to fall up not down in these airstreams. Didn't early Vigilantes have problems shedding the fueltank & nuke combinations that were planned to go backwards?

[Murph]

9 hours ago, Ossington 2 said:

I haven't read every note in this thread, so I might have missed it: What really happens when you drop bombs/tanks at these speeds? It is not unknown for ordnance to fall up not down in these airstreams. Didn't early Vigilantes have problems shedding the fueltank & nuke combinations that were planned to go backwards?

 

It depends on the store and on the aircraft.   That's why they conduct store separation testing for each store on each aircraft on each station and why there are particular envelopes specified for them in aircraft manuals.  It's worth pointing out that just because a particular store should be jettisoned/dropped/fired in a certain speed and G range does not necessarily mean that bad things (i.e. aircraft-stores collision) are going to happen outside that envelope.  It could mean that.  Or it could also mean that those are ranges to which it's been certified in testing and that the service did not want to spend further time, effort, and MONEY testing the separation characteristics to every possible extreme.

 

Regards,

Murph

Edited October 20, 2022 by Murph

[tweeky]

One of my RTU instructors flew the Lightning on an exchange tour.  He talked about one airfield defense mission where he took off, fought directly over the base, and landed running "on fumes".  Total flight time was 18 minutes.

 

Thats a long sortie, During the summer months at Binbrook, we'd sent 2 Lightning FMk3's up against each other (7600 lbs of fuel or full for the FMK3) from take off to landing was 10-12 mins or in ground crew speak a "brew" 

 

Many time I've sat and watched them tail chase on the slot I'd seen them out from because you knew you'd be back out again. The Sqn would fly a bucket load of trips and accumulate very little in Sqn flying hours.