Shamrock Extended [Stock]

[Exovian]

First off, a huge thank you to sal_vager for the original Shamrock orbiter, found here: ( http://kerbalspaceprogram.com/forum/index.php?topic=7514.0 ). I would also like to thank Kosmo-not; both of them have provided a great deal of inspiration.

Now, onto the ship: the Shamrock Extended, by Yarrow Quality Designs. Core Shamrock by Ker-Flow-Full Sewerage & Pipeworks.

The objective here was to make an ultra-light Munar lander. To that end, I took the most efficient orbiter I could fly, the Shamrock, and added a very rudimentary lander on top. I also add a trio of SRBs below to get the rocket off the pad. I have flown the craft to Munar orbit and back, but have not landed due to being unable to operate a no-ASAS lander without a bit more practice. However, half the lander\'s fuel was remaining once stable Munar orbit was achieved, so I think it\'s possible.

Flight can be difficult, so here is the method I used:

-Fire SRBs. Go straight up until they burn up, and toss them.

-Fire the Shamrock core stage at full throttle. Go straight up until 12,000 meters, then pitch over to 45 degrees.

-At 35,000 meters, throttle the engine down to half thrust.

-Once the apokerb is at 75,000 meters, turn of the engine.

-Once at the apokerb, burn horizontal to achieve orbit. This will deplete the fuel in the core stage, so use the lander to finish the burn.

-Once orbit is achieved, fly to the Mun as you would in any other ship.

Please leave feedback, I\'d like to see how others do with the ship.

[Kosmo-not]

With that last tank half empty once in mun orbit, by my calculation, you will not have enough fuel to land and return.

With half the tank, you have about 1200 delta-V remaining. You need at least about 580 to cancel out horizontal velocity, a little more for final descent and touchdown, and a little more than 835 to get back home. If we give the pilot a 100 delta-V budget for final landing, that\'s 1515 delta-V you need.

I give myself a 3000 delta-V budget from Kerbin orbit.

[Exovian]

I\'ll test that.

[togfox]

Kosmo, please explain or link where all these maths is drawn out. I have a spread sheet that calculates all sorts of things except what you just described. I get a lot of satisfaction working out the theory before try the practical. Thx.

[Kosmo-not]

Kosmo, please explain or link where all these maths is drawn out. I have a spread sheet that calculates all sorts of things except what you just described. I get a lot of satisfaction working out the theory before try the practical. Thx.

I use the Tsiolkovsky rocket equation to calculate the delta-V of a rocket. You get v_e by dividing thrust by mass flow rate. Assuming stock parts, this comes out to 5682m/s for regular fuel tanks, and 5952 for the half tanks (using one full tank is still better than using 2 half tanks, btw).

I know this will help you a great deal.

[Exovian]

I made an updated design using liquid engines instead of SRBs for the first stage, and it seems to fly much longer before running out of fuel. I\'ll do a full test tomorrow.

[sal_vager]

Nice little ship

Yeah liquids are a lot better in my opinion, I got fed up with the poor performance of solids.

As to landing, don\'t forget to hit capslock and just practice, on a ship this small your turn rate just becomes too high without using fine control.

Also remember it takes quite a bit of fuel to deorbit, land and then get back into orbit for the return trip, but saying that I have managed to reorbit and return on a single RCS tank with 3 or 4 thrusters, maybe it\'s possible to land the Shamrock? Then use its remaining fuel as a first stage launcher from the Mun and do the rest of the trip on RCS, It\'d weigh less as well.

Take a look at my Munar Skif, I managed to land it then fly back on RCS alone.

Munar Skif on Imgur https://imgur.com/a/WPNJ3#0