Rapier question

[SpacedCowboy]

Being just a Mun and Minmus guy, I'm thinking about taking that next big step, and go to Duna. I'll try a fly by probe first, and then hopefully graduate to a lander. So here's the question: Does the Rapier engine work in the liquid fuel mode in Duna's atmosphere?, or even minimally?, or should I just leave it out of my lander design? Appreciate any and all input.

Edited May 14, 2014 by SpacedCowboy

[Taki117]

No Oxygen in Duna's Atmosphere, Therefore the Rapier won't work.

[Claw]

No Oxygen in Duna's Atmosphere, Therefore the Rapier won't work.

I'm sure someone will point out that they don't work in air-breather mode but do in closed cycle (rocket) mode. So I might as well be first.

(I know that's what you meant, just heading off the "well if, but, then maybe")

[Taki117]

I'm sure someone will point out that they don't work in air-breather mode but do in closed cycle (rocket) mode. So I might as well be first.

(I know that's what you meant, just heading off the "well if, but, then maybe")

They are still not as efficient as other engines that could be used, especially for the weight. it would probably be better to use an Aerospike, or 48-7S for the lander

[cantab]

There's not much reason to use the aerospikes on Duna either, the pressure is so low at sea level that most engines will be near their vacuum Isp anyway. I suppose you could use one aerospike instead of three LV-909's to save space.

[Claw]

Yeah, sorry. I was just being difficult as they question was "do they work?"

I'm sure we could debate for quite a while which engine is "better."

[Pecan]

Or just consult travert, as I do when Red Iron Crown nudges me to paste the correct link (thanks).

Edited May 14, 2014 by Pecan

[The Destroyer]

But the rapiers look cool, so go for it in closed-cycle mode!

[Red Iron Crown]

The Rapiers key feature is its air breathing capabilities, take those away and it's a mediocre rocket engine. It only makes sense to me to use it where air breathing is possible, i.e. Kerbin or Laythe. If you're going to Duna, a dedicated rocket engine makes a better ship.

Edit: The Destroyer's point is good, if you just like the engine (and its quad exhaust is pretty cool looking) by all means go for it.

[SpacedCowboy]

I knew that Duna had a much lighter atmosphere but thought the Rapier might work to some extent. So I'm wrong. Thanks for the input. I will try something else.

[SpacedCowboy]

The Rapiers key feature is its air breathing capabilities, take those away and it's a mediocre rocket engine. It only makes sense to me to use it where air breathing is possible, i.e. Kerbin or Laythe. If you're going to Duna, a dedicated rocket engine makes a better ship.

Edit: The Destroyer's point is good, if you just like the engine (and its quad exhaust is pretty cool looking) by all means go for it.

No, I'm more into landing safely rather than "looking cool", Red Iron, I always take your advice into consideration

[cantab]

Yup, just Kerbin and Laythe for jets (including the Rapier in air-breathing mode) in the stock game. If you want to fly on Eve, Duna, or Jool you're limited to rockets, ions, and infiniglide. (The last being considered cheaty by many).

Mods of course give you more options. The kethane mod includes a jet that burns raw kethane with any air, while firespitter has propellers.

Back to the rapier, one of the interesting things is it's tied with the Mark 55 for the biggest gimbal range of any engine, at 3 degrees. Should you want a strong gimbal for some reason, maybe because your ship's CoM shifts off-axis, it might be worth trying. (Rapiers for main engines on a shuttle maybe?)

Edited May 14, 2014 by cantab

[Tortoise]

I knew that Duna had a much lighter atmosphere but thought the Rapier might work to some extent. So I'm wrong. Thanks for the input. I will try something else.

Duna doesn't have an atmosphere at all, therefore the airbreathing mode will not work on Duna.

And also, other engines may be more efficient.

[cantab]

Duna doesn't have an atmosphere at all, therefore the airbreathing mode will not work on Duna.

And also, other engines may be more efficient.

Duna certainly does have an atmosphere. It just doesn't have any oxygen in it.

[SpacedCowboy]

Duna certainly does have an atmosphere. It just doesn't have any oxygen in it.

Yes , I knew that Duna had "some atmosphere", just thought that rapiers would work at least a little bit, but , Oh well, Thanks for your input