Difference between revisions of "Tutorial:Returning From Eve"
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==Method 1 : Rendezvous and Crew Transfer == | ==Method 1 : Rendezvous and Crew Transfer == | ||
| + | ===Mission profile=== | ||
| + | It's a kind of interplanetary expedition rather than a simple round trip. In my opinion the easiest way is to send lander without crew and return rocket with 2 Kerbals. They'll meet for the first time in Eve orbit, one daring pilot will take seat in the lander and fly a historic mission! | ||
| + | |||
===Designing your Landing Rocket=== | ===Designing your Landing Rocket=== | ||
Ascent rocket will use asparagus staging (see [[Tutorials]]) with Upper and Middle Stage in a core and multiple Booster stages grouped in pairs. | Ascent rocket will use asparagus staging (see [[Tutorials]]) with Upper and Middle Stage in a core and multiple Booster stages grouped in pairs. | ||
| + | [[File:Eve Ascent Rocket.png|thumb|right|Tutorial's example rocket including probe and some electiricty equipment]] | ||
==== Upper Stage ==== | ==== Upper Stage ==== | ||
| Line 23: | Line 27: | ||
*[[FL-T400 Fuel Tank]] | *[[FL-T400 Fuel Tank]] | ||
*[[LV-909 Liquid Fuel Engine]] | *[[LV-909 Liquid Fuel Engine]] | ||
| + | |||
==== Middle Stage ==== | ==== Middle Stage ==== | ||
This stage will propel the ship through middle atmosphere (20km-35km). It's engine should be activated with all lower stage boosters and fed from their tanks: | This stage will propel the ship through middle atmosphere (20km-35km). It's engine should be activated with all lower stage boosters and fed from their tanks: | ||
| Line 28: | Line 33: | ||
*[[FL-T800 Fuel Tank]] | *[[FL-T800 Fuel Tank]] | ||
*[[LV-T45 Liquid Fuel Engine]] | *[[LV-T45 Liquid Fuel Engine]] | ||
| + | |||
==== Booster Stages ==== | ==== Booster Stages ==== | ||
There are two possible ways to build them. One is to use 2x[[FL-T800 Fuel Tank]] and [[LV-T30 Liquid Fuel Engine]]. Second is: [[FL-T400 Fuel Tank]], [[FL-T800 Fuel Tank]] and [[Toroidal Aerospike Rocket]]. They have very similar performance but I think aerospikes are better because they lower ship's drag coefficient. | There are two possible ways to build them. One is to use 2x[[FL-T800 Fuel Tank]] and [[LV-T30 Liquid Fuel Engine]]. Second is: [[FL-T400 Fuel Tank]], [[FL-T800 Fuel Tank]] and [[Toroidal Aerospike Rocket]]. They have very similar performance but I think aerospikes are better because they lower ship's drag coefficient. | ||
The basic rocket will have 3 pairs of aerospike boosters attached around the core stack. | The basic rocket will have 3 pairs of aerospike boosters attached around the core stack. | ||
| + | |||
==== Additional Equipment ==== | ==== Additional Equipment ==== | ||
You may also need parachutes and landing gear. | You may also need parachutes and landing gear. | ||
| Line 39: | Line 46: | ||
If you want to send lander alone to Eve, add somewhere a probe. | If you want to send lander alone to Eve, add somewhere a probe. | ||
| + | |||
| + | ===Designing Transfer Vehicle=== | ||
| + | Although it's not very challenging to send the lander in one launch, it may be easier to split ship into two parts. First will be the lander itself with decoupler below the center angine and [[Clamp-O-Tron Sr. Docking Port]] (remember about struts). The second could be simple [[Rockomax Jumbo-64 Fuel Tank]] and a couple of (for example 4) nuclear engines with this big docking port on top. Last thing to do is to launch them into Kerbin orbit, then dock and send to Eve. To dock together they'll of course need some RCS. | ||
===Designing your Return Rocket=== | ===Designing your Return Rocket=== | ||
| Line 49: | Line 59: | ||
*[[LV-N Atomic Rocket Engine]] | *[[LV-N Atomic Rocket Engine]] | ||
Such rocket has Delta-V of almost 6km/s which is enough for departing Kerbin's orbit, Eve capture, | Such rocket has Delta-V of almost 6km/s which is enough for departing Kerbin's orbit, Eve capture, | ||
| − | rendezvous with ascent ship and then return to Kerbin | + | rendezvous with ascent ship and then return to Kerbin. |
===Landing on Eve=== | ===Landing on Eve=== | ||
| + | Example lander has Delta-V of about 11km/s. Now it's all depends on the landing site elevation (the higher the better). To find suitable place you can use http://www.kerbalmaps.com/ or send earlier some scout probes or even better - a rover. With this type of design, to calculate needed Delta-V you can use results from my tests: | ||
| + | *9500m/s from 4,7km elevation | ||
| + | *10000m/s from 3.9km elevation | ||
| + | *10700m/s from 3km elevation | ||
| + | That leads to inaccurate rule of thumb that every 1km lower, adds 700m/s to the needed velocity change. Although I managed to return from 555m above sea level having 11.3km/s (with different design), with only 3 pairs of boosters we should not land below 3km, just for safety. <br> | ||
| + | *Note that adding another 3 pairs can bring landing site to below 1km at the expense of complicated design. | ||
| + | Once you got in stable orbit around Eve you can meet with return ship and transfer a pilot to the lander (via EVA). Then using transfer stage deorbit the lander to chosen landing site and then detach it. During descent get rid of that docking port (if used). When below 20km open first pack of chutes - the [[Mk25_Parachute]]. To reduce stress wait until 'Drogue' chutes full deploy, and then open first half of radial chutes. Once they deploy at 500m open the rest. If it seems you'll land faster than about 6-7m/s you can make slight burn prior to the touchdown. | ||
| + | When on the surface you can detach all those parachutes. | ||
===Ascending from Eve=== | ===Ascending from Eve=== | ||
| + | Before attepmting to takeoff - a quicksave. <br> | ||
| + | Now throttle up to 100%, detach landing gear, and as-quick-as-you-can point the rocket straight upwards. If failed to do so, rocket will flip. This will also happen if you try to move it before dropping all those boosters. Only things now are to drop spent stages and maybe control your velocity trying not to exceed terminal velocity (see [[Eve#Atmosphere]]). <br> | ||
| + | Start your gravity turn between 30 and 35km with ~70deg of pitch - at this time ship should be running out of fuel in the Middle Stage. When your apoapsis'll raise above 70km you can pitch down to ~20deg and keep looking both on fuel and apoapsis. <br> | ||
| + | Once having apoapsis above the atmosphere (~100km), cutoff the engine and plan manouver to circularize orbit. | ||
===Rendezvous with Recovery Vehicle=== | ===Rendezvous with Recovery Vehicle=== | ||
| + | Now if you managed to return from Eve surface rendezvous should be piece of cake. You can either adjust return ship's orbit to make a rendezvous or (if you have some fuel left) fly with the lander. When the distance falls below 1km or less (with nearly 0 relative velocity), you can EVA the lander pilot to return ship. | ||
===Interplanetary Transfer back to Kerbin=== | ===Interplanetary Transfer back to Kerbin=== | ||
| + | Delta-V needed for returning to Kerbin is: | ||
| + | *~1400m/s - departure from 100km orbit | ||
| + | *~400m/s - worst case plane change | ||
| + | So exactly 1800m/s would be suitable (the presented return rocket have much more). Calculations are accurate when planets are properly aligned - Kerbin should be aboud 36 degree ahead of Eve (for details see http://ksp.olex.biz/). <br> | ||
| + | After ~42 days, the most daring adventure will end up with reentry and safe splashdown. | ||
| + | |||
| + | ===Technical notes=== | ||
| + | *If you decided to use [[Mk1 Lander Can]] as a pod in this example rocket, note that safe landing elevation raises to 4,5km (with 3 pairs of boosters) and ~2,3km (with 6 pairs). | ||
| + | *If using more than 3 pairs of boosters, 24 parachutes may not be enough. Also Transfer Stage may became too weak. | ||
==Method 2 : Single Rocket Landing and Return == | ==Method 2 : Single Rocket Landing and Return == | ||
Revision as of 18:16, 30 September 2013
Because of the extreme difficulty concerning any return attempt from Eve, I have decided to write a separate tutorial.
Contents
- 1 Returning from Eve
- 2 Method 1 : Rendezvous and Crew Transfer
- 3 Method 2 : Single Rocket Landing and Return
Returning from Eve
Despite being the closest planet relative to Kerbin, it is extremely difficult to get a lander back into orbit around Eve. Additionally, you must overcome Eve's large gravity well in order to successfully return home, requiring even more Delta-V. As a result, many Kerbals have been lost in attempts to investigate their distant neighbor.
Though getting your crew home from the surface of Eve is extremely difficult, it's not impossible.
Specifications
- Length: 1-3 hours
- Difficulty: Very Hard
- For version: 0.20
Additionally, you will need a good understanding of orbital mechanics (see Tutorials section), angles, and a lot of patience. Some knowledge about aerobraking and Advanced Rocket Design might also be useful. Ships described below don't feature lauch vehicle, so any experience in building them is desired.
Method 1 : Rendezvous and Crew Transfer
Mission profile
It's a kind of interplanetary expedition rather than a simple round trip. In my opinion the easiest way is to send lander without crew and return rocket with 2 Kerbals. They'll meet for the first time in Eve orbit, one daring pilot will take seat in the lander and fly a historic mission!
Designing your Landing Rocket
Ascent rocket will use asparagus staging (see Tutorials) with Upper and Middle Stage in a core and multiple Booster stages grouped in pairs.
Upper Stage
This stage has to get above the atmosphere and accelerate itself to orbital velocity. It's important to keep it as lightweight as possible. First choose is a command pod. The best idea is to put single Kerbal in a EAS-1 External Command Seat. Next (but much worse) would be Mk1 Lander Can. I recommend first option and a following stage design:
- EAS-1 External Command Seat
- Inline Advanced Stabilizer // not necessary if you feel confident in piloting
- FL-T400 Fuel Tank
- LV-909 Liquid Fuel Engine
Middle Stage
This stage will propel the ship through middle atmosphere (20km-35km). It's engine should be activated with all lower stage boosters and fed from their tanks:
Booster Stages
There are two possible ways to build them. One is to use 2xFL-T800 Fuel Tank and LV-T30 Liquid Fuel Engine. Second is: FL-T400 Fuel Tank, FL-T800 Fuel Tank and Toroidal Aerospike Rocket. They have very similar performance but I think aerospikes are better because they lower ship's drag coefficient. The basic rocket will have 3 pairs of aerospike boosters attached around the core stack.
Additional Equipment
You may also need parachutes and landing gear.
- To save weight you can put LT-2 Landing Strut on a TT-38K Radial Decoupler.
- You may need Mk25 Parachute and it's best to put them on top of the boosters.
- For touchdown I used 24 Mk2-R Radial-Mount Parachute mounted on 12 TT-38K Radial Decoupler, two on each booster.
- Don't forget the ladder and some electric gear!
If you want to send lander alone to Eve, add somewhere a probe.
Designing Transfer Vehicle
Although it's not very challenging to send the lander in one launch, it may be easier to split ship into two parts. First will be the lander itself with decoupler below the center angine and Clamp-O-Tron Sr. Docking Port (remember about struts). The second could be simple Rockomax Jumbo-64 Fuel Tank and a couple of (for example 4) nuclear engines with this big docking port on top. Last thing to do is to launch them into Kerbin orbit, then dock and send to Eve. To dock together they'll of course need some RCS.
Designing your Return Rocket
Assuming that we sent ascent rocket alone the return rocket could be as simple as this:
- Mk16-XL Parachute
- Mk2 Lander-can
- TR-XL Stack Separator
- Advanced S.A.S Module, Large
- Rockomax X200-16 Fuel Tank
- LV-N Atomic Rocket Engine
Such rocket has Delta-V of almost 6km/s which is enough for departing Kerbin's orbit, Eve capture, rendezvous with ascent ship and then return to Kerbin.
Landing on Eve
Example lander has Delta-V of about 11km/s. Now it's all depends on the landing site elevation (the higher the better). To find suitable place you can use http://www.kerbalmaps.com/ or send earlier some scout probes or even better - a rover. With this type of design, to calculate needed Delta-V you can use results from my tests:
- 9500m/s from 4,7km elevation
- 10000m/s from 3.9km elevation
- 10700m/s from 3km elevation
That leads to inaccurate rule of thumb that every 1km lower, adds 700m/s to the needed velocity change. Although I managed to return from 555m above sea level having 11.3km/s (with different design), with only 3 pairs of boosters we should not land below 3km, just for safety.
- Note that adding another 3 pairs can bring landing site to below 1km at the expense of complicated design.
Once you got in stable orbit around Eve you can meet with return ship and transfer a pilot to the lander (via EVA). Then using transfer stage deorbit the lander to chosen landing site and then detach it. During descent get rid of that docking port (if used). When below 20km open first pack of chutes - the Mk25_Parachute. To reduce stress wait until 'Drogue' chutes full deploy, and then open first half of radial chutes. Once they deploy at 500m open the rest. If it seems you'll land faster than about 6-7m/s you can make slight burn prior to the touchdown. When on the surface you can detach all those parachutes.
Ascending from Eve
Before attepmting to takeoff - a quicksave.
Now throttle up to 100%, detach landing gear, and as-quick-as-you-can point the rocket straight upwards. If failed to do so, rocket will flip. This will also happen if you try to move it before dropping all those boosters. Only things now are to drop spent stages and maybe control your velocity trying not to exceed terminal velocity (see Eve#Atmosphere).
Start your gravity turn between 30 and 35km with ~70deg of pitch - at this time ship should be running out of fuel in the Middle Stage. When your apoapsis'll raise above 70km you can pitch down to ~20deg and keep looking both on fuel and apoapsis.
Once having apoapsis above the atmosphere (~100km), cutoff the engine and plan manouver to circularize orbit.
Rendezvous with Recovery Vehicle
Now if you managed to return from Eve surface rendezvous should be piece of cake. You can either adjust return ship's orbit to make a rendezvous or (if you have some fuel left) fly with the lander. When the distance falls below 1km or less (with nearly 0 relative velocity), you can EVA the lander pilot to return ship.
Interplanetary Transfer back to Kerbin
Delta-V needed for returning to Kerbin is:
- ~1400m/s - departure from 100km orbit
- ~400m/s - worst case plane change
So exactly 1800m/s would be suitable (the presented return rocket have much more). Calculations are accurate when planets are properly aligned - Kerbin should be aboud 36 degree ahead of Eve (for details see http://ksp.olex.biz/).
After ~42 days, the most daring adventure will end up with reentry and safe splashdown.
Technical notes
- If you decided to use Mk1 Lander Can as a pod in this example rocket, note that safe landing elevation raises to 4,5km (with 3 pairs of boosters) and ~2,3km (with 6 pairs).
- If using more than 3 pairs of boosters, 24 parachutes may not be enough. Also Transfer Stage may became too weak.
Method 2 : Single Rocket Landing and Return
Follow the steps of the two rocket method, ignoring the Rendezvous step.
