Hi Kev, that is a very good idea. I hope it flies.

700 kts is not M1.6, it’s hardly M1.2.. I was talking about max. speed…

Be careful with the statement. 700 kts is about Mn 1.06 at sea-level and about 1.22 at 35,000 ft+.

can you explain your reason in more detail?

i think J58 is turbojet engine rather than turbofan engine, there is no air go to fan section there.
Anyway this is a very informative video on SR-71 engine https://youtu.be/F3ao5SCedIk

Sure. There is an effect called ‘ram effect’ or ‘ram recovery’. It’s well known obviously, most people understand how a ram jet works, it’s the same basic working.
An intake is built to do a number things.
1. To provide enough air for the engine
2. To ensure the air-flow is presented in a stable condition
3. To slow the air-flow down below the speed of sound and effect a pressure rise.
A simple pitot intake is a divergent duct that slows down the air-flow and builds up the pressure
Variable geometry intakes do this by varying the type of duct dependent on the speed. Convergent when the air-flow is supersonic to transsonic and divergent from transsonic to subsonic.
The pressure rising also increases the total pressure ratio (PR) of the air that enters the engine’s combustion chamber. A typical example:
When Concorde was cruising at Mn2.0, the VG intake would slow the air down to subsonic (about Mn0.3-0.4) and build up the PR to 6:1. The engine compressor was delivering a PR of about 10:1. Total pressure ratio being 6 x 10, 60:1. The thermal efficiency (amount of heat turned into work) is better when the PR is higher. Said a/c had a thermal effiency of 47% when cruising, when it was static and running with 10:1 PR it was less.
Your second point is correct. USA does indicate rather easily what kind of engine it is. J=jet TF=fan T= turboprop. As I said though, most of the air was bypassed around the engine at dash speed (cruising Mn3.2).

going faster is inefficient in term of fuel use, that what it mean, an F-22*at supersonic wont use less fuel than a f-22* at subsonic.
Anyway, that isn’t where i focused my point. What iam trying to say is object move fast will have higher IR signature, and that a disadvantage of going fast

But it is still an incorrect term. Going faster is more efficient but uses more fuel….

@mig-31bm.
I don’t know where you got that last piece from but it is incorrect.
Supersonic flight need not be inefficient compared to subsonic. In fact the thermal efficiency is generally increased by the higher total pressure ratio.
They do use more fuel at higher speeds due to the drag law.
Just because it is written doesn’t make it true..

didn’t they solve twisting problems with new material?

Yes, they built the wings out of composite materials. It was also the way the fibre is layed (cross-laying to make use of it’s tensile strength in multi directional planes).

Seeing as the twin booms are less deep, I’m sure the second moment of inertia will play it’s part. They would have to be heavier to withstand any undue bending moment and flutter. Roll inertia would be higher as well.
@ Flanker_man. That is correct. The DH a/c were built twin boomed to reduce engine skin frictional losses. Why the Vixen was twin boomed and fitted with 200 series Avons is a good question. The Avon was more powerful than the Goblins and Nenes.