Re: [ERPS] This is one way to do it - Wonder it is works?

[Ian Woollard]

Henry Spencer wrote:

(By the way, why assume it's unmanned?

TIMTOWTO (- There Is More Than One Way To Orbit)

Making it manned is probably preferable.  Nobody builds unmanned cargo aircraft, and there's a reason for that.)
 

Yeah, aeroplanes were invented before microprocessors and GPS :-)

I think it depends a lot on the rest of the vehicle. I was toying with a 
VTVL stage and (VTHL) half(ves) architecture- but I didn't feel 
comfortable with sticking a person in the halves.

they're more reliable, need much less maintenance...
   

Modern airliner turbofans don't need much maintenance.  It's plausible,
even probable, that a point-design ramjet would be better, but whether
that actually makes a big practical difference is less clear.
Maybe. My engineering spider senses are twitching with a turbojet that 
was never expected to ever see 100 km+ though. Cold soak? Hot soak? 
Injector leakage at altitude? Any rubber, plastics or anything odd in 
the engine? How's that in a vacuum? Lubricants? Still, you could go over 
the engine with lots of care for that kind of thing I guess, but I 
wouldn't like to bet you'd catch all the problems; and any modifications 
may cause problems.

..and are cheaper to build/buy than a turbojet.
   

After how big a development bill?  Remember, there are no experienced
ramjet development shops left (at least in the unclassified world), and
engines which can't run at zero airspeed need expensive test facilities.
Unless you are talking about a big production run, buying used turbofans
is going to be a whole bunch cheaper.
 

There are advantages in becoming world experts though :-)

Ramjets are simple, so it may not be that bad at all. The flame holder 
is the hardest bit, you can hopefully avoid cooling issues by running 
the combustion relatively cool so that titanium can be predominately 
used, and that would help with the dry weight too.

Ideally you would integrate the ramjet and rocket, that's much easier 
than with turbojets- no, no idea how that works out.

                                                         Henry Spencer
                                                      [EMAIL PROTECTED]
 

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