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Build an MK3 Spaceplane after 0.90 update


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  • 2 weeks later...
Also, I would recommend swapping some of the rapiers for turbojets. They're more fuel efficient for getting to orbit and have higher thrust.

I hear that... Did they nerf the RAPIERs recently, or were they always this anemic? I put 4 on my MK3 spaceplane and it barely makes it off the runway. I have to empty the tanks so much to really get it flying that it runs out of fuel before I can make a full orbit.

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I hear that... Did they nerf the RAPIERs recently, or were they always this anemic? I put 4 on my MK3 spaceplane and it barely makes it off the runway. I have to empty the tanks so much to really get it flying that it runs out of fuel before I can make a full orbit.

Pretty sure they were always that way. The fuel efficiency from turbos is mainly that you can use turbojets alone to get a plane out of the atmosphere - then use rockets to circularize. The Mk3 parts are really heavy though.

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I hear that... Did they nerf the RAPIERs recently, or were they always this anemic? I put 4 on my MK3 spaceplane and it barely makes it off the runway. I have to empty the tanks so much to really get it flying that it runs out of fuel before I can make a full orbit.

RAPIERs, even in oxidising mode, produce a max of 175kN. Given that this [1] is what's on the back of my best Mk3...

screenshot382_zps6a535a62.jpg

...you might want a bit more thrust.

[1] Eight turbos, two RAPIERs, one Mainsail. And a partridge in a pear tree.

Edited by Wanderfound
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...I seriously did not expect this to get to orbit (one reason it's so ugly). The wings used to be fully delta'd out to the side, but it still liked to drop the nose at 15k, so in a fit of pique I ripped them off and noticed the TWR was much better now.

The engines are symmetrical on the underside, so 8 rapiers, and the 1.25m tanks are empty and just serve as mounting points. Obviously those can be replaced with something lighter! At the moment it'll push 0.97-1.3 TWR during ascent, and basically it's easier to just take it up like it's a rocket. Bit scary kicking to LFO mix at 22k and mach 2.5, but apparently the MK3 fuel tanks are quite capacious. Also forgot to switch over to the efficient 2.5m engine at any point because... I'm stupid. Maybe I'll just replace it with another 4 rapiers and try for a vertical ascent.

spaceplane-balista-beta.jpg

Still, circular orbit at 120 with about 500 dv left in the tank, not bad for an experimental shot for the sky :)

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Lol, I was shocked as well xD TWR over 1 feels a bit abusive, but it can be used to force things into the sky that really don't belong there :)

I doubt it can carry a payload in its current form, but if I swap the engine-I-forgot for 2-4 rapiers, it should be able to shove a satellite up. Time to experiment!

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  • 3 weeks later...

(Stock aerodynamics, no FAR or NEAR)

After many crashes and aborted launches I managed to make a clean, simple SSTO that can carry around 30 tonnes to LKO.

Note that I'm using the Intake Build Aid mod 0.90 to make sure the engines flamout evenly.

I hope it can inspire some people. The main design idea was to make the Rapiers with their intakes into simple units that can be easily placed on the wings, which otherwise has a tendency to bend upwards. Their weight counteracts this bending to a certain degree. The wings are also placed a bit high to get the thrust from the engines more in-line with the COG/Drag. Otherwise to keep the craft as simple as possible.

In preparation for flight, make sure to put the Rapier mode and intakes open/closed all connected to action groups, and also distribute intakes to engines by hovering mouse over any engine and hitting F7.

MK3 Spaceplane, 30 tonnes to to LKO:

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Further optimization is possible by perhaps moving the rocketfuel tanks forward and jetfuel back, since the COG moves perhaps too much backwards during flight. As well as placing the engines at different points on the wings. Note that this design is just made to carry a load to orbit. It can easily be modified to fly further itself though, by replacing the load with 30 tonnes of fuel, and perhaps adding an efficient rocket engine at the back.

Edited by Ninja_Thomek
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