Measuring Maneuverability

[mrbsct]

How do you measure the maneuverability of an aircraft or at least make good estimates? For example features like instantaneous turn rate, sustained turn rate, high angle of attack, pitch axis, yaw axis etc?

[sdkf251]

Interesting question.

In the very old days (early WW2 days heh heh heh ) they used to measure it by giving a given height, air temperature, wing loading information then g load information then turning radius determines which fighter is more maneuverable. (Thus the arguments that a Spitfire can outmaneuver an Me109, unless flown by someone like Joachim Marseille and so on and so forth ad infinitum)

But as turning radius became less fashionable as time went on since WW2, I am actually interested as how this is understood and measured these days.

[smsgtmac]

How do you measure the maneuverability of an aircraft or at least make good estimates? For example features like instantaneous turn rate, sustained turn rate, high angle of attack, pitch axis, yaw axis etc?

The standards have evolved as the weaponry has advanced. A backgrounder on energy-maneuverability here, but even then, pilot views may vary.

[sdkf251]

Many thanks smsgtmac! Great Read!

[zero-one]

Aircraft maneuverability can be measured in many differnt ways, and some aircraft excel in some ways but not so much onother metrics. Here are some ways to measure maneuverability, And some aircraft that are known to demonstrate prowess in them.

Instantainious turn rate: F-106, F/A-18, F-16, F-22, mig-29, Su-27,30,35, EF Typhoon, Rafale,
Sustained turn rate: F-15, F-16, F-22, mig-29, Su-27,30,35, Typhoon, Rafale
High Angle if attack performance: F/A-18, F-35, F-22, Su-27,30,35
Vertical maneuverability: F-8, F-4, F-14D, F-15, F-16, F-22, Mig-29, Su-27,30,35, EF Typhoon ,Rafale
Horizontal maneuverability: Mig-17, Mig-21, F-15,16,18,22, Mig-29, Su-27,30,35, Typhoon, Rafale
Post stall maneuverability: F-35, F-22, Su-30, Su-35
High subsonic maneuvering performance: F-15,16,22, Mig-29, Su-27,30,35, EF typhoon, Rafale
Slow speed maneuvering performance: F\A-18, F-22, Su-30,35.
Supersonic maneuvering performance: F-22, EF Typhoon (depending on ordnance carried)
High G performance: F-16,22, EF Typhoon, Rafale, Mig-29, Su-27,30,35.

Note that the F-35 is theretically capable of performing all of these except for supersonic maneuverability maybe, but until pilots flying block 3I or 3F comments on these, or atleast a demo is seen with all of this, then I cannot fully verify this yet

[sdkf251]

Aircraft maneuverability can be measured in many differnt ways, and some aircraft excel in some ways but not so much onother metrics. Here are some ways to measure maneuverability, And some aircraft that are known to demonstrate prowess in them.

Instantainious turn rate: F-106, F/A-18, F-16, F-22, mig-29, Su-27,30,35, EF Typhoon, Rafale,
Sustained turn rate: F-15, F-16, F-22, mig-29, Su-27,30,35, Typhoon, Rafale
High Angle if attack performance: F/A-18, F-35, F-22, Su-27,30,35
Vertical maneuverability: F-8, F-4, F-14D, F-15, F-16, F-22, Mig-29, Su-27,30,35, EF Typhoon ,Rafale
Horizontal maneuverability: Mig-17, Mig-21, F-15,16,18,22, Mig-29, Su-27,30,35, Typhoon, Rafale
Post stall maneuverability: F-35, F-22, Su-30, Su-35
High subsonic maneuvering performance: F-15,16,22, Mig-29, Su-27,30,35, EF typhoon, Rafale
Slow speed maneuvering performance: F\A-18, F-22, Su-30,35.
Supersonic maneuvering performance: F-22, EF Typhoon (depending on ordnance carried)
High G performance: F-16,22, EF Typhoon, Rafale, Mig-29, Su-27,30,35.

Note that the F-35 is theretically capable of performing all of these except for supersonic maneuverability maybe, but until pilots flying block 3I or 3F comments on these, or atleast a demo is seen with all of this, then I cannot fully verify this yet

Thanks zero-one. There seems to be a lot of categories. Is there a measuring unit for each category. For example in WW2 it was turn radius. (How far a plane would travel to complete a 180 degree turn. ( However, realistically, most of the time, this is usually very dependent on the pilot and tactics.)

On a more practical note within a squadron with the same type of aircraft, there would always be some "jinxed" plane that pilots really do not like to fly. So although official turn radius are given, not all aircraft can perform in the same manner despite being the same model.

With great advances in manufacturing technology, I guess that more or less, the F-35 would be more identical in structural integrity than ww2 "windmill driven planes". This should make the categories and measurements above
kind of more universal.

[zero-one]

There are too many variables to measure maneuverability in each of these categories.

For example the tightest turn radius of an F-16 block 52 is done at very slow speeds and at sea level, (5,000 feet or below)at around Mach 0.3 pulling just around 3Gs, but the radius is an extremly tiny 1546 feet

Now that would make it the tightest turn, but at that speed, the F-16 is basically a sitting duck.

The highest turn rate on the other hand is done at mach 0.6, still at sea level which is an 8G turn with a turn rate of around 21.4 degrees per second. However due to the higher speed, the turn radius will be larger.

The highest G turn on the other hand is done at Mach 0.9, still at sea level which is a 9G turn, the radius is larger, the turn rate is lower at around 18 degrees/second, but the speed is much faster.

All of this is according simulation models used on Falcon 4 which are close but not exact to the real thing.

And all of this are done on an F-16 with 100% internal fuel, 4 missiles and a jamming pod.

[sdkf251]

There are too many variables to measure maneuverability in each of these categories.

For example the tightest turn radius of an F-16 block 52 is done at very slow speeds and at sea level, (5,000 feet or below)at around Mach 0.3 pulling just around 3Gs, but the radius is an extremly tiny 1546 feet

Now that would make it the tightest turn, but at that speed, the F-16 is basically a sitting duck.

The highest turn rate on the other hand is done at mach 0.6, still at sea level which is an 8G turn with a turn rate of around 21.4 degrees per second. However due to the higher speed, the turn radius will be larger.

The highest G turn on the other hand is done at Mach 0.9, still at sea level which is a 9G turn, the radius is larger, the turn rate is lower at around 18 degrees/second, but the speed is much faster.

All of this is according simulation models used on Falcon 4 which are close but not exact to the real thing.

And all of this are done on an F-16 with 100% internal fuel, 4 missiles and a jamming pod.

Good point on the sitting duck. The only reason why maneuverability was such an important factor in WW1 and early WW2 was because it was seen as the best way to use your guns to hit the enemy aircraft. As time went on, speed became more important together with power.

So in a way, the weapon systems that an aircraft can employ determines the winning factor in the air engagement.
(This is assuming of course the weapon system works properly)

With the F-35, this will be quite different because the capabilities of the F-35 go beyond pure air to air/air to ground engagements. Although gun combat might never be ruled out, it seems the F-35 is better employed with other tasks than just going out and out-shooting enemies with guns.

[zero-one]

There are many intelligent posts on this forum that point out just how maneuverable the F-35 may be. And it is backed up by calculations and known facts about the plane.

One such comparison came from an aerodynamics engineer and concluded that if the F-35 ever found itself in a dogfight where guns may be needed, it would offer more maneuverability than an F-16 and F-15. The only way an F16 can outmaneuver an F-35 is if you made it totally void of weapons.

Basically a normal combat configured F-35 performs like a lightly configured F-16.

Some posters here would contest that an F-35 pilot who does get himself into a dogfight has already comited horrible stupid mistakes and would be thoroughly interrogated upon landing before possibly being relived of duty for being incompetent.

Although I would beg to differ, Gen. Mike Hostage was quoted as saying "an F-35 that does get into a dogfight has either made some mistakes,p or is facing a 2nd wave of fighters in highly contested airspace"

The possibility is there, especially for adversaries with large air forces like, Russia, China, Iran.

But as we saw, the F-35 is more than adequate to hold it's own in any type of fight. And pilots will continuously train for it.

[mrbsct]

Is Acceleration determined by Thrust/Weight?

When measuring how capable an aircraft is at accelerating, is thrust/weight the main factor?

Greater after burn thrust/weight is better instantaneous turns correct? And dry thrust and wing loading is greater for sustained turns and better corner speed? Also how exactly do you measure AoA?

[borg]

well, T/W is definitive a give away.
But then there is drag to consider. T/D.

Acceleration up to which speed?
All the way up, then the type of air intake(shock ramp etc) makes a difference.

Turbofans engine perform better at +15 deg temp and below. So different perforamce for a jet stationed in Alaska or Down in Mali, Afrika

Air pressure(altidude) has impact on both Acceleration and sustained AoA.

And then again we have lift which has impact at inst AoA and sustained AoA.

Example on sustained AoA:
F-4E With 30% internal fuel outperform a Flanker With 100% internal fuel.
But then again:

F-16
Block 40 with two empty underwing tanks and half internal fuel, can far outmanuver a clean Su-27 with full fuel load.
Block 40 with two full wing tanks and full internal fuel can be easily outmanuvered by an F-4E and 30% fuel load.

So here we have both T/W and T/D playing its part.

[zero-one]

https://hushkit.net/2019/06/10/an-idiot ... rformance/

An idiot’s guide to aircraft design – Part 4: Manoeuvre Performance

When we think of a fighter aircraft we think of its high manoeuvrability. Even today, this exciting and romantic trait is still highly desirable. We look at the best ‘turners and burners’ in service today and the science behind it.

A missile needs to be placed into the right section of sky to kill its target, and a fighter aircraft must also have a decent chance of dodging enemy missiles. High manoeuvrability also gives the fighter a greater opportunity to evade enemy sensors or eyes. Even when missiles can be told the position of their target not just through their own limited ‘vision’ by via the direction the pilot is pointing her head, or sensors both on and off the launcher aircraft, manoeuvrability is still valuable. High manoeuvrability is expensive though both in terms of the g-force it generates, and the demands it will put on the design of the aeroplane. The g-force, is a measurement of the type of force that causes a perception of weight. On Earth normal gravity gives us 1G conditions, and that’s what the human body is best at dealing with. A hard manoeuvring fighter can reach 9G, though greater G is possible, 9G is the effective limit of what the body can withstand repeatedly while performing the tasks required of a fighter pilot. At 9G a 100kg pilot would feel and move as if he weighed 900kg.

Over to Jim Smith for more: “For significant parts of the flight envelope, manoeuvre performance may be limited by the structural design of the aircraft, which is likely to be constrained to no more than 9g. This is due to the limitations of the human pilot, even supported by a ‘g-suit’. One key manoeuvre parameter is the instantaneous turn rate (the ability to suddenly pull a turn from level flight), which fundamentally depends on wing loading (how much weight each square of metre is supporting) and usable lift coefficient (in simple terms, how much lift is available to the aircraft). The significance is that this is a measure of how rapidly energy may be traded against turn rate to temporarily point the nose to the aircraft, for example to gain a firing opportunity, or to evade a threat such as a surface-to-air missile. Since supersonic combat aircraft have relatively low lift curve slopes*, due to sweep, and low aspect ratio wings, a number of the following may be used to provide a short-term increase in turn rate: Thrust-vectoring (the mechanical steering of the jet exhaust) provides a powerful way of nose-pointing, particularly at relatively low speeds; A delta wing with sharp leading edges will generate a leading edge vortex, which will increase both lift and drag; A leading-edge root extension (LERX) or strake may be added to a lower sweep wing to mimic the vortex flows generated by a delta and increase lift; Higher thrust-to-weight ratio may be required to overcome the drag at high incidence – particularly if the turn is to be sustained, rather than allowing energy to bleed off; Finally, unstable configurations are preferred, as these maximise the effect of controls. European and Chinese aircraft favour the use of a destabilising canard, while US aircraft generally do not, preferring closely-coupled tailed near-delta configurations.

*Lift curve slope is the amount of lift you get for a given angle between the wing and the airflow. Low lift curve slope means this is less than usual.

A leading-edge root extension (LERX) – the curving surface joining the front of the wing to the main body of the aircraft- may be added to a lower sweep wing to mimic the vortex flows generated by a delta and increase lift.

INSTANTANEOUS TURN
For instantaneous turn rate the aircraft may be either structurally limited to 9g, or aerodynamically limited by the lift available, dependent on the maximum possible wing lift (known as CLmax), speed, density and wing loading. Except for that area of the flight envelope where the aircraft is capable of delivering a sustained turn at 9g, energy and speed will reduce, and the rate of reduction will depend on Thrust to Weight ratio (high T/W reduces decay rate), and lift dependent drag (high lift dependent drag increases decay rate).

European and Chinese aircraft favour the use of a destabilising canard, while US aircraft generally do not, preferring closely-coupled tailed near-delta configurations. The Russian approach largely uses closely-coupled tailed near-deltas, but sometimes includes canards and in the near future , with Su-57, will include adjustable leading–edge vortex controllers (LEVCONs)

At altitude, at some point, an instantaneous turn rate of 9g will no longer be achievable because the wing will have reached maximum available lift, Clmax. Above this altitude, the turn rate available will depend on wing loading and Cl max, and the bleed off in energy will depend on T/W, and lift-dependent drag as indicated above. Thrust vectoring may assist in generating a rapid pitch response, as will an unstable configuration with an advanced flight control system.

maxresdefault

At transonic and supersonic speeds, wave drag will become an additional factor, with high wave drag increasing the speed decay rate.

From all this, we can extract the following pointers for good instantaneous turn rate:

– Low wing loading (the ‘wing loading’ is how much weight each square metre of wing is supporting)

– High max lift coefficient

– Thrust Vectoring

– Unstable designs with advanced Flight Control Systems

And for lower bleed-off in energy

– Low lift-dependent drag

– High Thrust to Weight

– Low wave drag if transonic or supersonic


The close coupled Euro-canards, Typhoon, Rafale and Gripen are likely to be very good; F-22 is also good due to high T/W, thrust vectoring, and wing area; Su-35 likely to be pretty good too – big wing, reasonable aspect ratio, canards, and thrust vectoring. F-35 will perhaps have more energy bleed off due to its higher wave drag, lower T/W, and higher wing loading

Best current aircraft: Difficult to assess and likely to vary dependent on Mach number and altitude, but suggest Typhoon and Rafale, with perhaps Gripen, F-22 and Su-35 also very good.


SUSTAINED TURN
However, the area of the flight envelope in which the aircraft will be capable of sustaining 9g will be substantially less than the area in which it can generate an instantaneous 9g turn rate. To generate and sustain a high turn rate, the aircraft will be relying on the extra energy available – as we have seen ((T-D)/W) x V, but with the wing at high lift.

For good sustained turn rate, we need:

– Low lift-dependent drag, and hence a higher aspect ratio

– Low wave drag if transonic or supersonic – noting this is likely to drive to low aspect ratio and high sweep

– High Thrust to Weight

– Low wing loading

The highly-optimised close-coupled Euro-canards are likely to be the best current aircraft; the Su-35 has higher aspect ratio but potentially higher wing loading. I suspect F-22 will be competitive, but F-35 is likely to have lower sustained turn rate, as it has higher wing loading. In considering the F-22 and F-35, one should remember that the operating concept for both is likely to avoid the close-in turning fight typical of within-visual-range air combat.




Flight at high-alpha seems to me to be a contentious requirement that, in general should not be a design driver. At high incidence, a combat aircraft is likely to be at low, or very low speed. While, given powerful control effectors, this may minimise turn radius and allow rapid change in nose pointing angle, the loss of energy may make surviving a missile engagement very unlikely, and re-joining combat difficult.

However, given the convergence of structural limits, and the limitation of airshow performances to subsonic speeds, high-alpha performance remains one way of impressing the tax-payers. With unstable aircraft, thrust vectoring and a host of other aerodynamic gizmos, the Su-35 is probably champion at this. But many of today’s aircraft have at least equally high thrust to weight ratios, and similar aerodynamic and structural performance at low altitude and subsonic speeds. Personal experience of displays by the F-22, F-35, Typhoon, Rafale, Su-27, Su-35 and even the less capable Super Hornet show that all of these can put on a jolly good airshow performance.



On turning performance, and generally awesome airshow characteristics, the canard-equipped, thrust-vectoring Su-35 gets my vote for high alpha performance. On more general manoeuvre performance, all the other aircraft mentioned are very capable, with Typhoon, Rafale and F-22 all benefitting from high thrust to weight ratio, clean aerodynamic design and sophisticated flight control systems.

You can tell he has a bias on the Typhoon when he consideres the Typhoon best at every category including High Alpha

[socalhornetpilot]

I can tell you from personal experience, that anyone who doesn't include the Legacy Hornet, either an A++ (small motors) or a C with big motors into a conversation about what jet maneuvers best in terms of instantaneous turns and AOA has never actually fought a legacy Hornet. This is also assuming all jets are of a similar configuration, simulating coming to a merge so no tanks and a center line LPOD for the Hornet. Few airplanes can throw their nose around like a Hornet, nevermind what you can do when coupled with JHMCS/-9x.

[outlaw162]

For historical perspective:

Turn performance: measured by how much your neck hurt after 2 BFM hops

Slow Speed and AOA performance: measured by how slow you could get before the engine compressor-stalled

Post Stall performance: measured by how many spin rotations before the drag chute became effective

Things are much better now.

[sprstdlyscottsmn]

I can tell you from personal experience, that anyone who doesn't include the Legacy Hornet, either an A++ (small motors) or a C with big motors into a conversation about what jet maneuvers best in terms of instantaneous turns and AOA has never actually fought a legacy Hornet. This is also assuming all jets are of a similar configuration, simulating coming to a merge so no tanks and a center line LPOD for the Hornet. Few airplanes can throw their nose around like a Hornet, nevermind what you can do when coupled with JHMCS/-9x.

Flying the Hornet (C Lot 20 with the EPE motors) in DCS, I agree. FWIW when a Hornet driver tested the module for handling and bomb dropping his biggest "complaints" where that BIT was too fast and speed brake deployment was too fast. Also, the thought that the F-35 flies like a Hornet with 4 engines? Holy Chit.