F-35 Cancelled, then what ?

[Engines]

To everyone,

I think it's a little unfortunate when forum protagonists (from whatever point of view) resort to personal observations. Honestly, it undoes the value of these forums, where interested people should exchange opinions (and if possible, a few facts) to mutual advantage. I'm not trying to be a moderator, just an observation.

Here are a few facts around F-35B ops from various surfaces. make of them what you will. (i've also read the AW article linked to by TBM-legend - thanks for that). I hope they help.

The potential impact of F-35B jet blast on all operating surfaces was recognised right from the start of the programme. As a result, it included a substantial R&D effort to build on the largely empirical data the team had from Harrier operations. This effort included modelling and testing of the environment (pressure, velocity, temperature) under the aircraft and on the surfaces. It also included special testing of the surfaces themselves, which included AM-2, concrete (various grades) and asphalt, on a dedicated rig at Warton. Oh, and it included flight deck steels with various coatings.

The basic drivers were and remain the temperature, pressure and velocity of the jet as it hits the surface, coupled with the heat transfer and mechanical characteristics of the surface itself. The main destructive effects were differential thermal expansion, strength reduction through heat, and in extreme cases melting, aided by dynamic blast effects.

The results from this effort were fed into the flight test programme, which will be validating the earlier data. From my recollection, there were actually few basic surprises. The tar in asphalt has a very low melting point (ever encountered a sticky road in summer?) and any static jet blast simply tears ip up quite quickly. Concrete is better, but the spalling effect (due to thermal expansion, not boiling water) has to be watched for. AM-2 is vulnerable due once again to a relatively low yield/melt temperature.

So, the F-35 programme does know about jet effects on surfaces, yes, it has thought about the issue, and yes, it has some ways forward. Those later.

Requirements - I can't go into so much detail, as I'm not current on the programme. But what I can say with some certainty is that the USMC, like the RN, realised some years ago that doing VLs to an unprepared surface in any STOVL jet was not a good idea. Moreover, for the forward basing concept, which was built into the detailed requirements set at the outset, the USMC did not require the aircraft to carry out VLs at the forward base, but a short landing within a given distance, with a given load of fuel and weapons. In fact, the landing weight specified for the 'FOB' was well above the VLBB requirement.

I'll just repeat that for clarity. The USMC did not intend to carry out VLs at forward bases, but planned to exploit the powered lift capability of the aircraft to carry out short runway ops.

Once you assume that, the situation changes quite a bit. You are no longer looking at a steady hot jet working directly on the surface at one location for the whole landing, but a short duration hot 'wash' across the surface. The thermodynamics of heat transfer aren't simple (to me at least) but I can say with some certainty that it's a very much less severe test for any surface.

Of course, for the shipboard VL, the surface does have to take the jet blast, which is why it was tested so extensively, and why new coatings are going to be adopted.

I suppose what I'm trying to point out, using facts, is that the F-35 programme is not being surprised by the challenges of handling jet effects on operating surfaces. They were thought about at the requirements stage. They have been modelled, investigated and tested, and are now being validated in flight test.

Jet powered lift is not easy. No one, least of all me, claims that is is. But it is doable, and (admittedly in my view) can be extremely operationally effective. The Harrier and Sea Harrier showed just how effective, coupled with RN, RAF and USMC innovation in basing and tactics.

I hope this helps a little.

Engines