It’s funny how you permanently use 36kft as a tropopause altitude, which is actually a tropopause at standard atmosphere.

This is the altitude at which the figure of M 2.421 is reached first, so it makes sense to use it.

On the other hand looking at Max designed Machs seems to be a problem, even so Metz says clearly that limits are broken easly at low altitudes implying the possibility of Max Mach of 2.2 being reached around 15.000ft (overspeed).

Considering the configuration (Normal Shock Inlets, supercritical wing profile, 42* wingsweep) it would make a lot more sense that F-22 being capable of M 2.2 at 15.000 ft/1600 mp/h than Mach M 2.421 at 36.000 ft.

Now add altitude to this and although i am ready to admit a higher pressure recovery ratio for F-22 the problem remains the same, the higher it goes, the more thrust it looses for the same Mach.

No – but when someone says an aircraft will break 1600mph – ie implying its around the top speed or at least the top speed he is willing to admit to.

Please post the stament. We will see.

For the time being you are inventing yourself standards which are not in use in his buzines, and definitely this is no standard at Edward AFB but PR talks.

It means you have the basic altitude range by logic – ie around 36kft.[/

It doesn’t mean such a thing at all, it only mean YOU assume it means this.

So, GS doesn’t solve the problem, due undefined altitude (difference between IAS and GS) and so again, you have variable as you have in Mach number.

Designwise this is not accurate, regardless of airspeed: Designed Mach numbers are the limit for obvious reasons.

You got your critical Mach, your Inlet Recovery ratio and Designed Structural Maximum Mach resulting on both from using Mach and not airspeeds for defining your design points, what matters here is not a theorical speed given in non-standard measurements but values we do not have from this stament i.e. those quoted above.

Wing aerodynamics and overall drag are at a minimum near the design speed of 1.5 Mach at 40,000 feet.
http://www.codeonemagazine.com/archives/2000/articles/oct_00/f-22/f22_1.html

This is what Paul Metz was saying of the F-22 design: F-22 Pilot Perspective

October 2000 issue of Code One Magazine.

This also mean that the optimum Designed Aerodynamic Mach for F-22 is around M 1.5 which is nothing new since it is using a supercritical profile optimised by NASA and 42* sweep angle wing, this profile also drags more at supersonic speed than a conventional biconvex laminary.

This defines its Critical Mach, drag polars but also its aerodynamic and structural Mach Limits.

Engines: (Same sources).

The big thrust comes from the incredible F119 engines. We sometimes forget about these beauties as they continue to perform trouble-free at all flight conditions—the perfect engine for a fighter pilot. They tolerate any throttle motions and pilot demands from ridiculously low speeds to supersonic flight at altitudes above 50,000 feet. Although the F-22 uses a fixed inlet design, the overall engine and airframe are optimized for the high supersonic speeds. Acceleration and Ps are phenomenal at the right hand side of the flight envelope..

So the inlet are Normal Shock with pressure recovery ratio falling with altitude and Mach faster than a multi-shock.

The possibility of higher pressure recovery ratios doesn’t mean F119 and F-22 are designed for higher Machs than 2.2.

The Raptor can easily exceed its design speed limits, particularly at low altitude. We have incorporated max speed cues and alerts to remind pilots when approaching the limits

NOW:

What was i saying? About the CLEAR possibility that this 1600 mp/h was in FACT an overspeed at 15.000ft giving the Maximum Mach of 2.21?

Cheers.

LOL! Now it get really FUNNY, they are using truckers measurements and datas at Edwards.

But of course we won’t be given the altitude and even less been told what the Designed Maximum Mach is, in particular the inlet recovery factor which would resolve the issue once and for all.

My ten pences on a Mach limit of 2.2 and an altitude for this stament of <> 15.000 ft, if the Raptor can’t do it at this altitude i wonder what its flight envelop polars would look like.

If you are given a Mach there is room for error

NO there is not.

Designed Mach limits always will give you an airspeed at all altitudes and still be a very viable measure expecialy regarding real-life design points and aircraft/inlets/engine limits.

The trucker’s solution on the other hand allows for such a difference between maximum, you might just as well tell us know that the Klingons have lost a ship in the USA 30 years ago and that F-22 is using their shielding technologies.

The important similarity parameter for compressibility is the Mach number – M, the ratio of the velocity of the object to the speed of sound M = V / a

The Mach number appears as a scaling parameter in many of the equations for compressible flows, shock waves, and expansions. When wind tunnel testing, you must closely match the Mach number between the experiment and flight conditions. It is completely incorrect to measure a drag coefficient at some low speed (say 200 mph) and apply that drag coefficient at twice the speed of sound (approximately 1400 mph, Mach = 2.0). The compressibility of the air alters the important physics between these two cases.
http://www.grc.nasa.gov/WWW/K-12/airplane/airsim.html

At least we have the honnesty to stick to the designed Mach limits for our aircrafts even when we have high airspeeds to show.

BTW BEST profile mission for F-35 shows a combat altitude of 7.000 ft which would give you a Mach 1.615 for the given <> 1.200 mp/h of some L-M publication, corresponding to the given Designed Maximum Mach of 1.6 (at BEST altitude); appart for this detail we don’t know what we’re talking about.

@LmRaptor

Please drop the superior tone and keep your lectures for your pals.

The day i need one i know where to ask and you’re not in my list, even if it’s quiet a short one.

I am done showing aspects of the issue to someone who deliverately REFUSE to admit they even exist while using non-standard measurement to make a false point based on datas which doesn’t allow him to define even the word speed and can only make assumption based on quasy nothing but PR quotes for airfans.

I was not trained at the local driving school and passed the age for magic roundabouts.

Cheers.

Does anyone know whether is the temperature of -56°C in tropopause an agreed, or actual measured value? Thx.

I have to check on my chart but it will depend on sea-level temperature (on local atmospheric variations), if it is standard it is easy to figure out.

You also can check on the Edward AFB handbook, tables 3.1 and 3.2 there sould be a reference to it including temps.

I’d take this with a pinch of salt. A common mistake is to convert a Mach number (at altitude) to mph (or km/h) using the agreed ratio for sea level (and a standard day). Undoing the math in the right way is thus often bound to fail.
I mean 1600 mph may translates to Mach 2.1. Because for those who don’t really care/know how Mach number varies with altitude, Mach 2.1 * 762 mph (sea level) = 1600 mph. Almost everybody (wrongly) do it that way.

Just my two cents though. Arguing on maximum speed is pointless anyway, mainly because the theoretical limits can often be exceeded (Mirage III, IV or 2000 going Mach 2.5+ dash comes to my mind, to name a few). Ditto for altitude, G load, etc.

My thaught exactly.

not Mach

WRONG: And please do not insist further into trying to imply it isn’t, some more advanced people than you are saying otherwise.

Mach IS a 1976 ICAO reference value and used for everything related to design points as sub, trans and supersonic flight regimes are calling for different solution and imposes different limits/solutions, it is also a value in itself within this International Atmospheric standard with a fixed speed of 1116.89 ft/s or 331.45 m/s.

Mach does

According to your own rigid theories it does, according to its international standard as i quoted and given the apropriate reference of, it doesn’t.

You insist into trying to pimply than only YOU knows and understand the subject when visibly you stick you one aspect only of the issue while using non standard measurements.

Happy or not Mr Raptor One, not only does this standard exist but is used by people like Paul metz and his collegues at Edward AFB and tother AF Base in the western world.

Also, Quoting someone who lives with these precise standards as job definition, using a non-standard value for “validating” a PR figure is not impressing me the slightest.

– its dependent on temperature and thus altitude as there is a standard temperature lapse rate as you increase your altitude. But speed is constant whether you are at 0 ft or 36000 ft….

And WHICH speed are you refering to exactly Mr Raptor One?

So when people use the F-22s speed – stated to be 1600mph

He uses a PR quotation which he wouldn’t if he was speaking to someone his size.

– they are using the correct reference for comparison – as it is constant.

NO they are not.

It is also non-standard and certainly does not allow you to make assumption the amplitude you allow yourself to, had he called a Vc, Ve or Vt then you would have been able to call it a “SPEED” and would have had to call it in kt as well.

If you know a machine is capable of X speed – you can work out its Mach at any altitude against standard atmospheric conditions.

WRONG, it is Designed Maximum Mach which will “give you” the speed you do, not theories based on non-standard measurements unsuable for proper calculation, mp/h are NOT a standard but PR figure.

And this NOT at ANY altitude but within the dynamic flight envelop of engine and inlets, but of course you prefer to ignore this reality as it allows yourself and buddies to try to pass a Designed Maximum Mach value for a F-35 KPP.

This is because one doesn’t know the particular ambient conditions of that particular flight.

As you do, so please keep the M 2.42 at 11 km for those who doesn’t understand what they imply.

What this comes down to is -according to Metz – the F-22 can do 1600mph – at altitude obviously.

Funny i was under the impression that there is a firm distinction between COULD and CAN and that Max Mach can be reached at 15.000 ft and still satisfy your trucker’s standard for 1.600 mp/h.

Therefore in standard conditions the F-22 is capable of doing Mach 2.42 at altitude.

😀

Which would be 50.000 ft.

Btw, using this standard of yours, a Rafale reaches M 2.247 at the same altitude.

Try again later.

wrightwing
But at altitude, the speed of sound is ~660mph, hence the M2.42. In any event the speed that was quoted was in mph, which is the same at any altitude. Too much pondering is going into a relatively straight forward statement.

Define at altitude please.

Since not one single of you lads can give us a proper measurement for the SPEED involved and have nothing to offer as for the altitude at which this speed is theoricaly atained, this stament is FAR from being “straightforward”.

Airspeed is IRRELEVANT; it is MACH and in particular the Designed Maximum Mach which matters, once and for all it is time fro you to get the meaning of design points and the limits they imply.

In the end he talked for public consume and the 1600 mph figure might well be suited to the usual citizen, who might not even be aware of knots.

Exactly Scorpion.

kt, ft are specificaly used for either sea or air navigation for a very specific reason, they fits the geographic measurement of the herath at the equator (1 mn of latitude) and the milibaric measurement of the athmoshpere up to the tropopause.

Before take off, windspeed is given in kt and atmospheric pressure in milibars.

This tends to simplify a lot the jobs of those who have to start with correcting local g values (when applies), ground athmospheric pressures, wind speeds etc to get as precise measurements as needed for the flight test.

If on top of this they had to loose their time with mp/h it would be rather nightmarish a job.