hey LM, what do you think of the aerodynamics of the Pak-fa so far?

We will have to wait and see, but they will probably end up being in the F-22, EF Typhoon class.

I am not quite buying that an A-A missile, designed for M2.8-M4.0 speeds can be draggier than its air-breathing carrier itself. Especially if carried as semi-recessed (AMRAAMs or Meteors on the Typhoon). The speeds you call supercruise for the F-22 are just a walk in the park for AMRAAM or MICA.

Interference drag – in the form of wave drag at supersonic speeds can generate localised shocks around the weapon – aircraft interfaces – pylons are bad for this and even conformal storage of weapons. Subsonically it’s much less of an issue.

Forgive me if I’m way off here, but if there’s visible condensation on top of the canard, isn’t that clear proof that the there’s a low pressure area on the top, meaning positive lift?

Almost certainly, as you need to factor in, the fact the turn itself is at some angle of incidence/AoA. This means the airflow will induce positive lift over the canard even if it is mechanically angled downwards by a small degree. In this case the canard is acting like an LERX.

The reason LERXs/canards angled like a LERX, are so good for high alpha performance is because you don’t want the flow to be laminar. The whole point of the fixed angle – tangential to the wing – is that it induces a turbulent vortex over the wing which is at much higher velocity and therefore much lower pressure than the laminar (relatively) airflow coming off an angled canard.

The problem with the canard at high AoA – even if angled like a LERX – is that its geometry – its sweep angle – prohibits the same level of low pressure generation over the top of the wing as a fixed LERX. The difference however isn’t that significant and probably only results in a fairly slight advantage for the LERX designs at high AoA. E.g a 30+ sustained AoA performance from the Eurocanards vs. a 40+ sustained AoA for fighters like the F/A-18E/F or the old Su-35 – the airshow beauty in the 90s.

and the laws of physics say some fighters can sustain over 60 deg alpha from max fuel to 0 fuel sens – not that it is a relevant combat capability – instantaneously it is likely possible for each and every modern fighter to exceed 100 deg alpha + if not limited by FCS/AoA limits.

The F-22 will pick up on any Link-16 activity.. unless the sneaker is only receiving Link-16 data.

A deployed AIM-9M (same seeker as the 9L) can not see more of an area as the APG-77, so there is no benefit to coverage area. However, the RCS and range of the F-22 will be seriously compromised having those bays open (all the time too).

A better option would be to bring the tech of the EODAS into the F-22’s MLD, as LM is planning. It would also provide a better detection range into the MLD than even the 9X could provide. Let’s hope they get this into the Incr 3.3 timeline.

I know the LM website claims the algorithms required to update the MLD software to detect other FJ’s are only planned – as they have for years now – but from what both DJCROSS – an engineer on the F-22 and Showers have implied – the capability is already a reality.

One of the reason’s the F-22 needs no IRST – as DJCROSS put it – is the fact it has 360 deg MLD coverage. This is supported by a bit of literature – where the F-22 MLD situational awareness is fused into the with the rest of the integrated sensors – I’d not bet against the the F-22 being able to detect aircraft at BVR ranges with 360 deg ranges thanks to the MLD’s currently installed.

It also would lend support to the claim that Showers made about the F-22 not needing HMD to cue the 9X to exploit its full envelope.

Ok I understand. Is there any publication/articles about the use of this capability during exercise or tests by the F22. I never heard it was used operationally but I certainly missed something…Is this a theoretical capability or is it used on a regular basis ? For the moment I am under the impression that it is like rumors similar to “active cancelations”. But I would like to stand corrected if I am wrong.

It’s all very classified of course – but this is the basis by which the F-22 does BVR all the time. I doubt they’d make a multi-billion dollar fighter program without an on board means of visual ID. 🙂 Engineers and customers adapt to new demands.

The F-22 and its APG-77 radar will also be able to employ better Non-Cooperative Target Recognition (NCTR). This is accomplished by forming fine beams and by generating a high resolution image of the target by using Inverse Synthetic Aperture radar (ISAR) processing. ISAR uses Doppler shifts caused by rotational changes in the targets position to create a 3D map of the target. The target provides the Doppler shift and not the aircraft illuminating the target. SAR is when the aircraft provides the Doppler shift. The pilot can compare the target with an actual picture radar image stored in the F-22’s data base.

http://www.globalsecurity.org/military/systems/aircraft/f-22-avionics.htm

How do you know they the same when there are loads of different reference wing area methods????

Boeing Wimpress
ESDU
Airbus Gross
Trapezoidal Reference

To name a few.

What is the F-22s average t/c?!?

No sweep doesn’t give better crit mach reduction than t/c – look at tier one sizing parametrics of it – a percentage change of t/c does more to reduce crit mach than a percentage change of sweep angle.

You probably get confused because you don’t understand that the theory doesn’t match reality – simple wing sweep theory is based on the assumption that the wing has infinite span – which in reality is not the case – which is why engineers were surprised to see that sweeping the wing didn’t give them the desired/predicted results.

The resulting sweep on the Typhoon was not driven soley by crit mach – there are numerous other factors that came into play. Size/Cost/Fuel/Roll specifications that constrained it as such.

Thus you can’t say which of the two wing profiles has a lower crit mach. The funny thing you also haven’t realised is the degree of curvature on the canopy of the Typhoon is greater than that of the lower canopy on the F-22 – the first supervelocities – could easily form on the canopy before the wing.

Dude go and read Raymer/Torenbeek/Stinton/Roskham?

Stinton page 33 – the design of the aeroplane 2nd edition.

Cola – a higher swept wing designed with similar technology will generate a lower coefficient of lift to start with – therefore lower lift per unit area. Thats based on simple sweep theory – where the actual airflow over the wing is represented by Mfreestream*COS(sweepangle).

The change in cl from the unswept version of the same wing would be CL = cl(unswept)*(cos(sweepangle)^2) in radians. Thus lowering the t/c of an aircraft with lower sweep – doesn’t mean it generates less lift per unit area – its all a compromise/tradeoff. This all applies as long as the mach cone off the nose is outside the wing tip. With the F-22 and the Typhoon this would only not be the case … at some point past Mach 2.

Also – the wing reference areas used on the F-22 – do not include some of its highest peaks of lift generation – the chines that mold into the intake at high AoA generates the lowest pressure regions around the jet.

It is also typical for the European reference wing areas to include more than the equivalent US methods. So using wing area is as a comparison is simplistic – without knowing if the method being used to compute them is the same – if it includes all relevant lift generating surfaces – and without knowing the respective CLs. Not to mention what effect a combat load has on the pressure distribution around the aerofoil.