Ride of the Valkyrie?

I am reluctant to continue with my Concorde until its new fan and ESC arrive. Everything needs to be significantly tested before the fuselage is fully skinned as thereafter access will be virtually non existent.

Jokingly I said I had ordered enough parts to make the 6 engined XB70 so out of curiosity I found a nice detailed 3 view.
As a model it would be rather more 'compact' than Concorde with a span to length ratio of 1:1.7 rather than the huge 1:2.5 of Concorde.
I was not seriously considering 6 EDFs but with its engines grouped together underneath and the fuselage on top there was possibility of squeezing in a single large EDF but still using the scale inlet and exhausts. The rather complex ducting shape required would not be particularly efficient but overall would still likely be better than 6 tiny EDFs. It would also be a great deal cheaper!
So looking at the various cross sections what was the largest circle that could be put inside?

The section with the circle in it is at about 50% chord.
It would take a bit of careful design to insert such a large EDF without weakening the structure but not impossible.
So some ratio calculations to determine the size of the plane for a given size of EDF.
Keeping to my 'light and cheap' philosophy HK do a basic plastic 70mm fan so how big would the XB70 have to be to house it?
The answer is a span of just 31" (787mm) or in other words a bit smaller than my Concorde and it would be much shorter!
It would however probably be prudent to make it a little bigger than that, say 34" (863mm), to give more 'wiggle' room to get the fan in.
Using a 3s the 70mm fan generates nearly twice the thrust of the 4x40mm and uses less current as well so some losses from the more complex ducting shape would probably be acceptable.

Am I going to build it?
No
Well not yet!

i bet we see a start tonight sir.

I really do like this aircraft, as a youth in the 1960s I drew up the plans for one powered by a single Jetex 50. Your thread has got me thinking again, as a small Rapier project it just might work. Is a 50 year layoff acceptable in modelling terms I wonder...........

I'll follow this one with interest Q, and if you need a little push t get started we could have a friendly to see whose flies first. As Eric so rightly put it, "Garn, you know you want to.........."

I love this aircraft, but I think it should be turbine powered.

I not starting honest!
Just a bit of doodling.
A possible fan location.

Making use of the nose wheel bulge under the fuselage places the fan virtually at the front.
Only the inner 4 exhausts would be used and probably without individual nozzles as like that it gives about 85% of the FSA and would significantly reduce the duct wetted area.

Only the second one built could actually cruise at Mach 3. The first exhibited some instability above 2.5.
Unfortunately the second was destroyed by an accident during a photo shoot in 1966.

Come on Q dont be shy, you know you will eventually

Garry

A bit more though doodling.
In the first sketch the fan was so far forward it was partially ahead of the inlet.
So with just a minor adjustment to the nose wheel bulge the EDF can be moved back so its bell mouth is flush with a inlet.

Overall the duct would have a shape not unlike a hot water bottle!

As I have absolutely no idea how to actually make such a thing this will have to go on the back burner for a bit!

A little bit more thinking.
The original had the usual variable nozzle jet pipes.
A bit of scaling of the 3 view showed the nozzles reducing by 75%, probably in their supersonic configuration, so it would be perfectly scale to have them opened out slightly to say 85% which is the recommended nozzle for a EDF.
And it just so happens that six scale jet pipes with 85% nozzles is also almost exactly 85% of the area of a 70mm circular duct.
Something like this.

So at the back of my mind would be an experimental duct on a EDF than converts the outlet into 6 individual nozzles that have a total area that was 85% of the FSA.
If it lost say 30% of the thrust in doing this then a single EDF XB70 with scale inlets & exhausts becomes a possibility.

The size of this thing amazed me when I saw a program on one of the Discovery channels, a bloke was standing in one of the engine intakes and you could have put another one on his shoulders, blooming ginosorous.

At 550,000 pounds it was at the time one of the heaviest planes in the world and it flew at 70,000ft at Mach 3.
Although cancelled as a bomber it did spur the Soviets to build the Mig25 to intercept it.
The 2 prototypes were slated to provide research information for the American SST which would have had a similar weight & performance.
Given that the 747 was entering service which halved the typical seat/mile cost you can understand why the airlines gave the American SST such a big no!

What was the SST

Fly-Navy wrote: The size of this thing amazed me when I saw a program on one of the Discovery channels, a bloke was standing in one of the engine intakes and you could have put another one on his shoulders, blooming ginosorous.

Was it this one by any chance? Haven't watched it myself yet but seems to be the only one I can find on Youtube.