First question - Does anyone know of efforts to make or research nozzle extensions made of memory metal?Second question - What limitations do memory metals have that would preclude using it as described above?Wikipedia is always a good place to start, http://en.wikipedia.org/wiki/Shape-memory_alloyThis is cute, I easily find references using the force generated by shape changing memory metals, but little (read that as nothing) about changing the volume of anything similar to a nozzle or a container.Edit Add: After sleeping on it, it occurs to me that corrugation of the nozzle extension in a spiral pattern would reduce both the diameter and the length of the nozzle extension.
We used to call that occupational slot the inflight missile repairman.
Wouldn't hydraulic actuators be more reliable than memory-metal? I am thinking of something like the tailpiece of some military fighter jets that have 'petals' that can squeeze the exhaust. They would have to be pretty beefy though.
In the Sol departure phase, a battery of orbital lasers illuminates a 16 kilometer diameter photon sail attached to the ship's nose (sail not shown)
The aerospike engine eliminated the need for a nozzle and compensated with altitude...
From the site that Randy posted:QuoteIn the Sol departure phase, a battery of orbital lasers illuminates a 16 kilometer diameter photon sail attached to the ship's nose (sail not shown)What's a "photon sail", exactly? A light sail by a cooler sounding name?There's also a "matter-antimatter" engine, for the coast time to Alph Centauri. The top of the page has the web author stating , "The good starship ISV Venture Star from the movie Avatar is one of the most scientifically accurate movie spaceships it has ever been my pleasure to see". Bit of a struggle for me to accept not the science, but the existence of that engine. Certainly "Dr. Pellegrino is one of the worlds greatest living experts on the Titanic", but it's rather a stretch to parley that expertise into interstellar spacecraft design.Anyhow, those engines "burn for 0.46 year, producing 1.5 g of thrust, thus braking the ship from a velocity of 70% c to zero". 0.7c, huh?The site is still chock full of interesting stuff. Moving on to Thrust vectoring...The first thing that came to my mind was the "turkey feathering" trick, used on some jets these days. It was interesting to me to study the adjustable "plug nozzle" design. I also liked the idea of a magnetic nozzle.
From the site that Randy posted:QuoteIn the Sol departure phase, a battery of orbital lasers illuminates a 16 kilometer diameter photon sail attached to the ship's nose (sail not shown)What's a "photon sail", exactly? A light sail by a cooler sounding name?
There's also a "matter-antimatter" engine, for the coast time to Alph Centauri. The top of the page has the web author stating , "The good starship ISV Venture Star from the movie Avatar is one of the most scientifically accurate movie spaceships it has ever been my pleasure to see". Bit of a struggle for me to accept not the science, but the existence of that engine.
Certainly "Dr. Pellegrino is one of the worlds greatest living experts on the Titanic", but it's rather a stretch to parley that expertise into interstellar spacecraft design.
The site is still chock full of interesting stuff.