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Low-level speed of Cold War aircraft


Doc72

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On 8/25/2020 at 6:13 PM, Mountain goat said:

"They would fly around at Mach 0.95, 650kt give or take a bit, and they trained at 10m. We flew through firebreaks in trees, we flew all over northern Sweden at 30ft, and we never went below 600kt.


An interesting video of them crazy Swedes:

 

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I've been told F3's have chased down F-111s and B-1Bs low level over Alaska with missiles (IIRC 2 Skyflash, 2 Aim-9).....they got the kill, needed fuel pretty quick after however. The F3 was very slippery low level from what I know. 

 

High speed at low level is a nice defence, a Tornado IDS isn't gonna mix it with a Su-27 or MIg-29...best to just run in different directions.

 

The B-1 can shift on the deck for a very long time IIRC, they can run anything out of fuel trying to chase if they can't catch quick enough to get a shot. 

Edited by mirageiv
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I am just reading 'Panavia Tornado' by Bill Gunston (1980). The book is, of course, very enthusiastic about the Tornado as the aircraft tailor-made for the low-level interdiction and strike role. It mentions the "LLDF (low-level discomfort factor), measured as the number of 0.5g bumps per minute at high-subsonic speed at sea level".

Gunston gives the following numbers for the LLDF:

Tornado 0.8

F-104  5.4

F-15 12.2

F-16 12.9 (F-18 similar)

F-4 15.0

According to Gunston, the last three American fighter are thus in a region where crew performance is severely degraded.

 

Is this LLDF a real thing or just something taken out of Panavia's sales brochure? (Nowadays, with most operations at medium altitude this feature of the Tornado lost its importance anyway.) 

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3 hours ago, Doc72 said:

Is this LLDF a real thing or just something taken out of Panavia's sales brochure?

Both, in essence. Ride quality is a very real consideration at low level, not only for the comfort of the crew but also for the life of the airframe. 

For a given speed and assumed degree of low-level mechanical and thermal turbulence, ride quality is heavily influenced by wing loading, but also by the positioning of the cockpit in relation to the other major masses and some other factors. 

It's not just a "nice to have". If you are going a long way at low level then it may well be the difference between being fit enough to function at the other end of the leg, or being so beaten up that you're exhausted, and failing in your mission.

No doubt there are some fancy Panavia metrics being used here but yes, you would expect a high-loading type like a Tornado or F-104  to give the crew a dramatically easier time down in the weeds than something with a big wing designed for high-level turning performance, which the F-15, F-16 and F-18 all were in their origins.

 

I would have instinctively put the Phantom perhaps somewhere in the middle but I haven't really gone into the numbers, and there may be other factors affecting that in addition to wing loading. Some aircraft have artificial measures built in to their stability augmentation to improve gust response, and maybe the earlier generation Phantom is less clever in that regard than the newer-generation teen fighters.

 

Edited by Work In Progress
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On 06/09/2020 at 07:56, mirageiv said:

High speed at low level is a nice defence, a Tornado IDS isn't gonna mix it with a Su-27 or MIg-29...best to just run in different directions.

 

I read somewhere (Buccaneer Boys perhaps?) that a four ship Bucc formation if bounced would split on the basis that the fighters might get one if they were good and lucky but three would still take out the target

6 minutes ago, Work In Progress said:

Both, in essence. Ride quality is a very real consideration at low level, not only for the comfort of the crew but also for the life of the airframe. 

 

When Roland Beamont was testing TSR2 down low and fast he wrote that the Lightning chase plane was being bounced around so hard the pilot was in difficulty just staying in there whereas in TSR2 it was steady as a rock.

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I recall it being said that the Buccaneer wasn't that good at low-level except that the cockpit was at a structural node so that the pilots thought they were having a smooth ride.  Which worked, but ate up the fatigue life.

 

The Jaguars regularly flew Card 4 at red Flag, something the defenders learned pretty quickly,  So when two F-15s dropped down behind the rear pair, the Jaguars were in Card 6.  Not a trick that would work very often, but Jaguars 2 F-15s nil that day.

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15 hours ago, Work In Progress said:

Both, in essence. Ride quality is a very real consideration at low level, not only for the comfort of the crew but also for the life of the airframe. 

For a given speed and assumed degree of low-level mechanical and thermal turbulence, ride quality is heavily influenced by wing loading, but also by the positioning of the cockpit in relation to the other major masses and some other factors. 

It's not just a "nice to have". If you are going a long way at low level then it may well be the difference between being fit enough to function at the other end of the leg, or being so beaten up that you're exhausted, and failing in your mission.

No doubt there are some fancy Panavia metrics being used here but yes, you would expect a high-loading type like a Tornado or F-104  to give the crew a dramatically easier time down in the weeds than something with a big wing designed for high-level turning performance, which the F-15, F-16 and F-18 all were in their origins.

 

I would have instinctively put the Phantom perhaps somewhere in the middle but I haven't really gone into the numbers, and there may be other factors affecting that in addition to wing loading. Some aircraft have artificial measures built in to their stability augmentation to improve gust response, and maybe the earlier generation Phantom is less clever in that regard than the newer-generation teen fighters.

 

Thanks, this confirms what I have thought. I think, I read somewhere that the very short fuselage of the Tornado (with the characteristic huge fin extending beyond the fuselage) is also designed to improve ride quality. If the aircraft oscilliates around the center of gravity (or lift) in the center of the aircraft, a short fuselage reduces movements of the cockpit area.

It's ironic that the Tornado is probably the best aircraft in the low-level attack role, but less than 10 years after it entered operations, this role was no longer required (Gulf Wars, Balkan wars, Afghanistan, Syria).

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It is more complicated: not a single vibration but a series of standing waves that cancel out at certain points along an aircraft.  (I am not the best person to explain this!)  If the cockpit is at a quiet node, then it's a smooth ride.  If not, it's rough.  Tornado was designed for this - I'm not sure but think TSR2 was also - if not they were very luck with that long fuselage.

 

I'm not so sure that low-level operations are quite as obsolete as suggested.  The wars you list have all been operationally stage-managed by the US, which has invested massively in electronic warfare and Suppression of Enemy Air Defences, so can stroll in at high altitudes and operate with weapons that actually require this.  Lesser nations can either operate under the US umbrella - and fitting in with the US operational plans - or the benefits of going under and around enemy radars still applies.  It is of course Stealth by operational means rather than aircraft design - another very expensive technology.

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6 minutes ago, Hook said:

Isn't missile range severely degraded when popping one off from high level into dense air at low level?

 

Cheers,

 

Andre

 

Not really, on the contrary launching from a higher level adds a bit to the energy of the missile thanks to gravity. At the same time the missile detector may find the acqusition of a target against the ground more difficult compared to a similar target against the sky, but this would depend on the type of the detector and its properties.

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48 minutes ago, Graham Boak said:

It is more complicated: not a single vibration but a series of standing waves that cancel out at certain points along an aircraft.  (I am not the best person to explain this!)  If the cockpit is at a quiet node, then it's a smooth ride.  If not, it's rough.  Tornado was designed for this - I'm not sure but think TSR2 was also - if not they were very luck with that long fuselage.

 

I'm not so sure that low-level operations are quite as obsolete as suggested.  The wars you list have all been operationally stage-managed by the US, which has invested massively in electronic warfare and Suppression of Enemy Air Defences, so can stroll in at high altitudes and operate with weapons that actually require this.  Lesser nations can either operate under the US umbrella - and fitting in with the US operational plans - or the benefits of going under and around enemy radars still applies.  It is of course Stealth by operational means rather than aircraft design - another very expensive technology.

 

I seem to remember that the location of the cockpit in the TSR.2 was designed to be at a structural node of the fuselage, so same as the Tornado.

Ideally not only the cockpit should be located in such a place but also the various black boxes, as viibrations at low level flight can affect these.. or better, it could in the past. Today electronics are much more robust from this point of view and vibration tolerance specifications are very stringent.

 

Regarding the value of low level operations today, the problem is that overflying the target at low level is very dangerous and this was made very clear in Desert Storm. The need to avoid flying over certain targets has led to the development of a good range of stand-off weapons like Storm Shadow/SCALP and others and these are becoming more and more common with many air forces. They'd be used in the first strike wave to take down radars and control centres and at that point the path would be clear for all aircraft to operate at higher levels. The ongoing war in Libya is apparently seeing quite some use of such weapons by all those air forces that are not officially there but are nonetheless in theatre...

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Low level fly Su-24, aircraft with special system for low level flight:

As writes Wikipedia

Su-24 may have speed  on low level 1400 km/h but on 200 meter altitudes:

"Su-24
Maximum speed:
 at an altitude of 200 m: 1400 km / h (without suspensions)"

 

Other Soviet strike aircraft:

 

"Tu-22M


 Maximum speed:
 near the ground: 950 km / h [44]
[44]- limitation in combat units introduced according to Combat Use Course."

that is, in fact, the Tu-22M can develop a high speed at the ground.

MiG-25RB
"Maximum speed (at altitude), km / h (km) 1000 (0) [55]
[55] -  Practical aerodynamics of the MiG-25RB aircraft, Military publishing house of the USSR Ministry of Defense, 1978, page 88"

 

Now for the interesting part.  It is believed (at least by the majority of today's youth and teenagers) that the Internet has everything .... complete nonsense! 😁

The text below is not in the Russian-language segment of the Internet in text form, the English-language translation of what is not even worth mentioning, so this is somewhat exclusive:

"On May 11, I had a chance to fly in a strategic B-1B in the command chair.  On the right is an American pilot-instructor.  We sailed over the Nevada desert at 500 miles per hour, at an altitude of 300 pounds.  From high altitudes, after refueling in the air, they descended almost in a vertical dive with a vertical speed of more than 100 m / s.  The machine was brought out with a noticeable overload.  The antiaircraft maneuver was performed in a downright fighter manner.  Why, right after takeoff, a roll up to 60 degrees with a climb on afterburner.
 - Not risky for such a heavy machine?  How does it compare to the Tu-160?
 - The Americans fly boldly, with greater rolls and overloads than our pilots.  Our Tu-160 is one and a half times heavier, but with minimal refueling it could afford such maneuvering.
 We went to the tactical bombing range on the model of the airfield.  With the control stick in hand, I dropped to one hundred and fifty pounds.  For them, it was below the limits.  And I'm not new: commanding a regiment of Backfires, I walked at forty meters (true).  The Americans were pleasantly surprised.  But after their second warning: "General, we don't fly like that," I was forced to occupy "their" echelon - 300 feet.
 - But did anything make an impression on you too?
 - The most powerful is flying along the envelope on the machine.  The mountain ridge rushing towards us at a thousand-kilometer speed was highlighted on the displays and was visually visible with all its peaks.  And so, when it seemed that the collision was inevitable, the machine gun reared the car and steeply directed it into the zenith.  Only passed the highest point of the ridge - he threw the plane into a dive.
 Then we piloted "on hand".  I don’t know how I would have succeeded if I hadn’t fly in my ea Tu-160, when he had not yet entered the unit.  Only seven flights, but it came in handy ..."
 From an interview with the Commander-in-Chief of the Air Force of the Russian Federation, Colonel-General Pyotr Stepanovich Deinekin, a member of the editorial board of the  Krylya Rodiny

magazine
 p.19 article "Who Will Raise the Blade?"  "Крылья Родины/ Krylya Rodiny" magazine   1993 - 3"

 

https://en.m.wikipedia.org/wiki/Pyotr_Deynekin


https://ru.m.wikipedia.org/wiki/Дейнекин,_Пётр_Степанович
Colonel-General Pyotr Stepanovich Deinekin,
First class military pilot.  As a ship commander and pilot-instructor, he has flown more than 5,000 hours without accidents on piston, turboprop and turbojet aircraft: Yak-12, Yak-18, Yak-18T, Yak-52, Li-2, Il-14, Il-103,  Tu-16, Tu-22M2, Tu-95, Tu-104, Tu-116, Tu-134, Tu-160, MiG-AT, MiG-29, MiG-31, Su-25, Su-27, Su-  29, Jaguar IB, B-25 Mitchell, B-1B Lancer and Po-2.

 

There is a less emotional mention of this in the book:

"Bombers": p. 259, volume 1

" The B-1B is inferior to its Russian counterpart Tu-160 in a number of characteristics:
 maximum carrying capacity, range, maximum speed, but aerobatic
 the qualities of both machines are about the same.  This is evidenced by the Air Force Commander
 Russia P.S. Deinekin, who in May 1992 visited the United States in response to
 1991 visit of a representative of the US armed forces to Russia.  May 11 Deinekin
 perfect
 sewed a flight on a B-1B bomber.  The plane took off with a small mass (about
 150 t) and after refueling in the air, which took place 4 m after
 takeoff, went to the polygon zone (Nevada) to practice a strike on tactical
 target, which was a model of the airfield.  Distance flight to target
 about 800 km took place at an altitude of 90 m in automatic following mode
 terrain with a flyby from above and a bypass in the horizontal plane
 obstacles, the height of which reached 1500 m.
 a tactical bomb attack on a target and performed an anti-aircraft maneuver, after which
 control of the aircraft was transferred to Deinekin.

 Honored Military Pilot Deinekin before being appointed Commander-in-Chief of the Russian Air Force
 was the commander of long-range aviation and is well acquainted with heavy bombers.
 He has extensive experience in piloting the Tu-22M bomber, on which he
 1976 flew at altitudes up to 45-50 m (100 m instrument), he performed
 also several flights on the Tu-160 even before the adoption of this aircraft in the armed
 nie.  Therefore, piloting the B-1B aircraft for him was not
 Problems.  He tested the plane in several modes and in the end dropped to
 heights of 65 m, and then 50 m. The American pilots were "pleasantly surprised" and
 emotionally declared that "our generals do not fly like that."

 According to Deinekin, expressed in a conversation with the authors of the book, B-1B has
 approximately the same handling characteristics as the Russian Tu-160, however
 practical methods of control of the B-1B and Tu-160 are very different due to different
 piloting techniques adopted in the USA and Russia.  for example, when piloting
 Russian heavy aircraft are subject to stronger restrictions on
 overload, when landing, the plane does not go in a box, but turns around
 "pancake".  American pilots fly boldly on rolls, overloads,
 range of heights and "piloting the strategic B-1B as a front
 bomber. "For example, immediately after takeoff, an American pilot laid
 turn with a large (up to 60 °) bank.  After refueling in the air,
 on the
 an altitude of 6000 m (he gained this height in 4 m thanks to a high rate of climb),
 automatic mode following the terrain at an altitude of 90 m
 was executed with a steep dive.  Before landing, B-1B flew along
 box with abrupt turns (roll 30-45 °) and sharply decreased ("fell like
 iron ") for planting. Among other advantages of the American plane Deinekin
 iron "noted good ergonomics and high quality of instruments in the B-1B cocpit  
 (the indicator screen has a nice bottle color, the artificial horizon tracks
 the slightest rolls)."

http://forums.airbase.ru/2004/12/t6222--b-1-vs-tu-160.html

 

Now, think about the problems with the resource that the B-1B are experiencing, of course, less sparing operation is to blame for this in comparison with their counterparts from other countries, but it is quite possible that low-altitude flights also played a certain role in reducing the resource of the B-1B  ?  Therefore, perhaps low-altitude flights and a safer way to break through the air defense, but while you work it out, it will eat up the life of your aircraft and you simply have nothing to break through the air defense when the hour "X" comes?

 

B.R.

Serge

Edited by Aardvark
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One more data point: in Arthur Reed's 'F-104 Starfighter', page 45 it is written that 'Luftwaffe pilots say they can reach Mach 1.3 on the deck without any trouble'.

 

I also seem to remember a remark that the Germans flew low-level with tip tanks at speed far outside flight manual limits, but I can't find that now.

 

Rob

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4 minutes ago, harvy5 said:

Su-25 pilots in Czechoslovakia trained LLF in 50 meters and the speed of 650 km / h.

That reminds me of a nice little story. A few years after the wall came down, a Czechoslawak researcher stayed at our university lab for maybe half a year. He was a former MiG-21 mechanic (conscript), and told me the most dangerous missions flown by his unit where those trying to intercept simulated cruise missiles, that flew very low of course. That surprised me, I had never thought about that mission. I think he said they had lost 1 or 2 aircraft with it.

 

Rob

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6 minutes ago, Rob de Bie said:

That reminds me of a nice little story. A few years after the wall came down, a Czechoslawak researcher stayed at our university lab for maybe half a year. He was a former MiG-21 mechanic (conscript), and told me the most dangerous missions flown by his unit where those trying to intercept simulated cruise missiles, that flew very low of course. That surprised me, I had never thought about that mission. I think he said they had lost 1 or 2 aircraft with it.

 

Rob

It was a common training to overcome AA defense.

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I used to fly with a lot of ex RAAF Mirage and F-111 pilots.

 

F-111 story, positioning a jet from Amberley to Darwin and forgot he was carrying his external stores pod full of personal kit. Went a little too fast and exceeded the max speed for the external stores pod and was greeted in Darwin by ground crew with “you didnt bring a suitcase today sir?”

 

Mirage, basically go as fast down low as you could get it to go. Was bringing his wife a sewing machine in the external stores pod on the belly  purchased in Butterworth and returned to Darwin and pulled way too many g’s in the break and split the pod down the middle.

 

The sewing machine was found embedded in a hangar about 6 months later.

 

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Mirage looks a bit like SAAB J35 Draken (a pure delta with no tail) and it's performance seems to be similar. You could fly a Draken at low level above Mach 0,9 but below 1,0; "Leaning against the pole" as we called it. This is a region where drag quickly increases and the ride is rough and unpleasant. The aircraft's nose also yawed from side to side. Fuel burn was of course huge; only with the big drop tanks you could fly from Helsinki to Rovaniemi AB in Lapland.

 

Cheers,

Antti

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14 hours ago, Antti_K said:

Mirage looks a bit like SAAB J35 Draken (a pure delta with no tail) and it's performance seems to be similar. You could fly a Draken at low level above Mach 0,9 but below 1,0; "Leaning against the pole" as we called it. This is a region where drag quickly increases and the ride is rough and unpleasant. The aircraft's nose also yawed from side to side. Fuel burn was of course huge; only with the big drop tanks you could fly from Helsinki to Rovaniemi AB in Lapland.

Antti, do you know more about that yawing behaviour at M0.9? I've read similar accounts of the A-5 Vigilante and MiG-27, the latter at supersonic speeds. I'm also thinking of the small yaw damper 'rudder' below the real rudder of the F-104A/C.

 

Rob

Edited by Rob de Bie
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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.

 

Draken can be flown at supersonic speeds at low level even with drop tanks, missiles etc. and the ride is pleasant.

 

I have to check the aircrew manual for accurate figures.

 

Cheers,

Antti

 

 

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On 9/18/2020 at 1:00 AM, Rob de Bie said:

I'm also thinking of the small yaw damper 'rudder' below the real rudder of the F-104A/C.

 

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

8 hours ago, Antti_K said:

 

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.

 

Draken can be flown at supersonic speeds at low level even with drop tanks, missiles etc. and the ride is pleasant.

WOW!

.....interesting...  we knew about these features of Draken, or Sweden was not taken seriously in the event of a hot phase of the conflict and therefore they simply did not pay attention to Draken at headquarters ...

 

B.R.

Serge

 

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