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Archive for the ‘Motivation’ Category

Modern manufacturing technologies enable strange shapes and could produce unconventional pumps. What is good for small scale rockets if turbines and centrifugal pumps have too much tip losses?

Rotary engines have vastly better power to weight ratios and vibrate less than piston engines. They’re also expensive and hard to build (cue modern manufacturing again). Here is one demonstrated in a paramotor, Parajet Cyclone using a Rotron engine. Love the music.

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Watch in high res at youtube. White Knight Two doesn’t look so large span after all. Spaceship Two is pretty wide with its outset elevons and the WK2 outer wings need to have the engines so there’s not much wing outside with the single purpose of lifting (or stopping the tip vortex). It seems both planes are really light too. Carbon fiber throughout. SS2:s wheels are really tiny. They have gone for minimum dry mass. The landing speed doesn’t seem huge even with its low aspect ratio. Maybe the size misleads. The landing is very smooth.

Of course the couple climbs out very fast even with gear out since SS2:s tank is empty and it doesn’t have the solid fuel onboard either.

I’m reminded of the lifting body research of the sixties. Who says we aren’t experiencing the golden age of aerospace right now? There’s happening interesting stuff left and right now, most of it in the more modest programs.

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Or The Space Game, by ESA.

The Space Game Screenshot

Minimize delta vee by moving the planets around (this changes the probe's arrival time at the planet). This shows my best solution so far, with some playing one evening, about 13 km/s

This is a nice javascript webpage where a probe is shot from Earth to Jupiter with gravity assists at Venus (twice), Earth and Mars. You try to achieve the lowest propulsive delta vee. You decide when the spacecraft arrives at each encounter and the program basically calculates the rest. It’s quite a nifty little piece of Javascript, the future of web applications is like this. It works fine with Chrome on Linux at least. Probably IE will have problems but who uses that anyway?

I’m ranked at #39 at 12.74 km/s… Far behind the gurus who get below 10 km/s readings! There are apparently some prizes for the top three, but I think people are in it for the fun of it.

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Alina Orlova from Lithuania

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..is despicable.

They take clearly too little water.
They take it clearly too slowly.

They idle far too much at the beginning.
They idle far too much at the end.

They do not offer fast forward capability like mechanical machines did.
They do not show their current status like mechanical machines did.
They’re often broken like mechanical machines were.

They make it unclear which programs have pre-wash and which don’t.
They make everything else pretty unclear too, like what a particular button does.

An ideal washing machine:
Large intake hose (or two if it is a model that takes warm water too where district heating or wood heating is available). When the user presses start, the machine starts taking water at full speed at that precise microsecond, unless it is gauging the weight of the laundry.
Laundry weighing will be done in a few spins, after which water intake commences with no delay.
A display shows the state of the machine. At least the following states are displayable: pre-wash, wash, rinse, spin.
A fast forward mechanism moves the machine to the next state.
A stop mechanism stops the machine in any state.
After the laundry is spun, the machine can spin slowly and reverse a few times to unstick the clothes from the drum walls, but this can be stopped and the laundry removed from the drum immediately.
The spin is braked so it doesn’t take minutes to coast down.
The temperature of the wash can be changed even if the program or wash has already started without having to reset or flush.
The spin cycle can be enabled or disabled even if the program or spin has already started without having to reset or flush.
Extra water can be enabled in the middle of the program.
etc etc.

All this was possible with seventies mechanical logic industrial washing machines. Note that almost all of it is pure logic whose cost is pretty much exactly zero once you’ve developed it, and other things like large hoses are trivial improvements.

If you will use this specification when designing a washing machine, then send me a machine: I will test it and say what improvements still have to be made.

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By Katharina and Salla.

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Rand Simberg talks about impedance matching. So I’d like to make a post of my comment there (I’ve always wondered why this obvious alternative gets mentioned so little…)

What to do when you arrive at Mars or Earth with your solar electric propelled vessel?

So, the problem with most low fuel demand velocity change schemes is that they only give slow accelerations. Low fuel high velocity change means solar or nuclear electric propulsion and aerocapture mainly.

High delta vee aerobraking is hard to do in one pass – it gets dangerous because of atmospheric variability and potentially other reasons.

Simple: detach a small capsule with the humans that goes directly to the surface (with only days of life support) and leave the untended craft to do multi-pass aerobraking. Hitting van Allen belts a few more times or taking a long time doesn’t matter that much with no humans onboard.

You could also potentially ultimately leave the long distance craft at some Lagrange point instead of LEO. (Cue some clever and complex maneuvers to save fuel – maneuvers that take long.)

Something similar could also be done when a long distance stack is assembled in LEO: send the humans there only after it’s through the belts. They can go with a smallish capsule again. Potentially at some Lagrange point, or in space without any fixed reference, just along the way. It could be dangerous though if the capsule doesn’t have much life support.

Many of these things have potential delta vee penalties as well as timing inflexibilities, but they could have enough other benefits that they should be considered.

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