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/sci/ - Science & Math

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4087698 No.4087698 [Reply] [Original]

Anyone feel like helping me design a reverse thruster that would be needed to safely land the rover curiosity on mars. I need to include thruster nozzle diameter and
momentum flux (pV2) leaving the nozzle

Its finals week, I am not asking you to do it just asking you to help me out. It is an in class project tomorrow and I wanna get it done as soon as possible so I can study for my linear algebra test

>> No.4087709

>>4087698
just base it on a quadra coptor.

>> No.4087725

>>4087698
>>nozzle diameter and
momentum flux (pV2) leaving the nozzle

Is that all you need to know? Just set your V2 to really really high and use a small mass rate. Just shoot some nanoparticles out at a good fraction of the speed of light.

>> No.4087742

>>4087725

well i have to take in account the mass of the rover....gravity of mars and atmospheric pressure.

>> No.4087748

>>4087742
Do you have to take into account mass of fuel and change of the weight of the rover due to burning fuel?

>> No.4087986

>>4087748
no

>> No.4088086

It would be a fairly basic conservation of energy problem if you're allowed to make assumptions like no atmospheric friction. Ep is the total gravitational potential energy of the mass of your lander with respect to the surface of Mars. Ek is the total kinetic energy of all the mass your rockets pump out during the descent. Ep = Ek.

You've got to make some design choices such as if it should have a slow smooth descent all the way down or free fall and blow its load decelerating in the last fifty meters.

>> No.4088099
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4088099

>>4088086
>Conservation of energy
>For THIS problem

>> No.4088113
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4088113

Okay... momentum flux integrated through nozzle area will give you impulse per unit time = force. Of course, the amount of impulse needed to arrest the descent can be determined from the (under-parachute) descent RATE (presuming it is provided), mass of the vehicle, gravity, and duration of your burn.

I'm not sure how atmospheric pressure plays into this yet, you'll have to explain further to illustrate how it matters. Are you actually looking at the effect of back-pressure on a C-D nozzle? Are you using a simplified (incompressible-flow, Bernoulli) model for the thruster? Is this a fluids course?