You are right about heat being a major problem for hypersonic aircraft, but don’t you think that by the time that the SR-72 enters service around 2030 that Lockheed might have come up with a way to dissipate heat from the aircraft without compromising the aerodynamics?

No.

Simply no.

At least, not in the way you mean rather than the way your technically writing. Heat soak might not be an issue, but a reduced IR signature certainly will be unobtainable. Its like trying to hide a meteor flying across the sky…

I have never claimed to be. But half a lifetime devoted to that profession has given me a good grounding in the realities of engineering development and programme timescales. So the timescale I suggested for a hypersonic vehicle was not pulled out of thin air,

You are one of the (few) members on here I pay heed to. I know you’ve extensive experience and I’m not daft enough to ignore it… even if I disagree with it!

but based on a programme that I judged to be of similar complexity to the ‘SR-72’.

What programme would that be?

Or, in the likely assumption its hush – did that program:
– have a novel propulsion system?
– have to incorporate that propulsion system with at least 1, maybe two, other propulsion systems?
– operate in an environment that never has had sustained flight-times before?

Each one of those is a massive issue in itself that could take 10 years to solve.

I do not see the relevance of your question. The fact that it has not been done says nothing about its feasibility.

Feasibility of… a test system? No. it says nothing of it. If a test program is scoped down to a very limited set, no reason why they couldn’t achieve goals next year (by dusting off an X-51 for example).

Feasibility of an in-service system? Much more complex. That is where I think the proposal passes from challenging to ludicrous.

Nobody would disagree with this. Any programme intended to deliver a major advance will involve significant challenges. But I have spoken with US propulsion engineers who seemed confident of solving the hybrid-propulsion problem. And Russia is also involved hypersonic technology, and has active programmes.

Timescales my good man, timescales.

As you know given enough time, you’d be fairly confident of getting anything done when there is a fundamental physical understanding present.

But, to do so within a set time-limit is a different story altogether. Even things like the systems design to deal with heat-soak in hypersonic flight is problematic.

‘Company-bashing’ seems to be an established hobby on this forum. It is one that I do not participate in. (Out there in the real world, I try not to do Powerpoint presentations either, but some clients insist on it.)

I love company bashing. Its a great opportunity to vent and talk sh!te. You should try it.

Rage against the machine man – its the way forward. An easy start is, pick your “favourite” piece of software… mine is currently patran – then go off on one about “how the f88k is this thing industry standard!” 😎

The Lockheed A-12 went from drawing board to first flight in two and a half years, and that programme did not require the sort of pooling of effort that you are implying.

But the operation of RAmjets had been ongoing for about 30 years and NASA had flight test campaigns ongoing for well over a decade.

The two are not comparable.

As an engineer, I see no reason why a hypersonic hardware could not be flying four to five years from go-ahead, with initial operational capability following some two to three years later.

Your not the only engineer in the house.

To date, is there any aircraft that has taken off, reached speeds in excess of Mach 4 and landed, all under its own power?

To my knowledge, the only examples – and its really stretching the boundaries – are the space shuttle/Buran.

The hybrid propulsion technology does not yet exist. Although NASA’s X-39 may be a nod to this. However, given its running since the mid-90s and may not be connected, combined with the difficulties evident in the X-43/X-51 programs – there would appear to be significant challenges to overcome before any significant sustained (non-rocket) hypersonic flight will be achieved. If there were a few more flight tests, or X-planes devoted to the subject, I’d be more accepting of your timescales.

As it is…. yet another Lockheed Powerpoint show which is full of promise and short on reality.

Yes it could be disinformation like Reagan’s Starwars but then the A-11/SR-71 program was soooo well known before it was made public.

RAMjets first flew in the 1930s.

The A-12 first few in the 1960s.

Now as you are the expert on U.S. black projects give us more information.

You are completely delusional if you think this proposal is in any way shape or form realistic.

I am not even going to bother descending into an argument with someone who quite clearly has such a limited grasp of the difficulties involved.

Something of interest…

http://rspa.royalsocietypublishing.org/content/469/2160/20130512.full

There is a requirement for radar to be able to distinguish true ‘targets’ from ‘clutter’ (other scattering objects which might be mistaken for a genuine target, and so generate false alarms). An example would be in distinguishing certain types of electronic circuits that might be hidden through burial alongside metallic garbage where traditional radar and metal detectors are triggered by false targets (‘clutter’) to an extent that search operations become unacceptably slow. An example requirement is for radar that would detect and identify covert communications or espionage devices hidden in the walls of buildings, or within natural objects (e.g. stones, trees) or electronic equipment present in locations (caves, woodland, garments, rubble or snow) where its presence indicates potentially hostile human activity or catastrophe victims in need of rescue. One feature that may be used to distinguish between clutter and a target is based on nonlinearity. For instance, many electronic components can scatter radar signals nonlinearly if driven by a sufficiently strong radar signal, in contrast to naturally occurring objects which tend to scatter linearly.

While this doesn’t immediately translate over to a complete “anti-stealth” X-band radar, it is useful.

It is widely accepted that the primary means of achieving VLO is through use of shaping to try and direct an incoming signal toward several azimuthal directions. What isn’t re-directed because of the aircraft surface will have weak returns off other external structure and off internal structure.

A second signal which is inverted can help determine the presence of semi-conductors in that internal structure, which won’t follow the linear re-direction properties of an “inert” structure (like a panel or spar).

It will help reduce clutter on high power radar returns, greatly reducing the onus on classic signal filtration and meaning GCI* could become much more effective at picking out VLO targets.

But, it’ll still need lots of power.

*this could extend to larger SAM fire-control radar I suppose.

During the 1991 Persian Gulf War the Mig-25 was ineffective. In a limited number of sorties Mig-25s achieved one kill, and lost two aircraft. Once again the Mig-25 was proven to be vulnerable to the AIM-7.

What were the numerical odds?
What supporting infrastructure did each side have?
What was the expertise of each pilot?

To me, a 1:2 ratio given the overall operating environment says much about the qualities of the MiG-25.

No, I actually don’t see any indication there that you were talking about the same thing I was. I suppose you might have been, but that would only make the discussion of turn radius all the more odd.

So should I spell everything out in multi-coloured crayon in future?

If you present yourself broadside to the missile, then go into an inverted 9g dive at the optimal distance – then yes, you can easily work out the missile does have to achieve similar turn radius*.

If you present your tail to the missile and go into a 9g pitch up – then no, the missile doesn’t need anything like the same turn radius as the vector differential is less.

[I did mis-spoke earlier using the instance of directly running away as it is numerically incorrect.]

*following on from this… its a bit too early in the morning for my brain to be fully woke up yet – but to dodge a single incoming missile… presenting yourself head on and going into an inverted 9g dive at the optimal distance would mean the missile has to significantly beat your turn radius due to the vector differentials involved. Wouldn’t it? Surely someone has automated the radar/MAWS/RWR to provide cuing for what the pilot should do for best evasion…

If I get time later, I’ll run through the numerics of it. Could be next week by the time I’ve a proper chance though.