Useful MK2 cargo bay payloads

[Duke MelTdoWn]

On 9/7/2023 at 6:18 AM, miklkit said:

I use MK3s a lot as only they have the carrying capacity and range to do anything really useful. 

This comment prompted me to revisit my designs for a Mk2 Moho Lander and do a full test flight. The (mediocre) results can be found below.

Do you have a nifty Mk2 payload? Please reply below!
____

Skyfly XI + MoEM IX (Steam Workshop)

The test flight of Skyfly XI + Moho Excursion Module VIII completed its objective to land on Moho, refuel with ISRU, and return to Moho orbit with enough fuel to land again. 
So the trip and biome hopping is doable, but landing and mining is a pain. And the route back to Kerbin by refueling NIPS in orbit is only a dim hope to keep morale up.

Mk2 Advantages:
- Moho mission with biome hopping possible.
- Low launch mass and price. Full system price of Skyfly XI + MoEM VIII is only ~150,000; total launch mass 92 tons.
- High recovery value. Only some small LF tanks are jettisoned during the whole mission.
- Style bonus for using plane as first stage.

Mk2 Disadvantages:
- Mk2 form factor sucks
-- Lander/Miner tends to get tall, skinny and top heavy, compounded by the small footprint of the landing legs. This makes it topple over easily.
-- Can only fit a Convert-O-Tron 125, so refueling the Miner takes long (3 days with 5* engineer).
-- Can not fit a lot of Kerbals on the Miner.
-- No Lab possible.
- Way back to Kerbin questionable.
-- Miner can not transport a lot of excess LF to refuel NIPS (interplanetary transfer stage) in orbit. Many trips would be required.
-- Landing on Moho with NIPS attached is impossible.
- Part clipping can get borderline abusive.
-- Staging of the NIPS tanks is very sketchy. Produces a lot of debris.
-- Reactionless headbutt drive fixed in MoEM IX.
- I was not able to make a Mk2 cargo spaceplane where the CoM does not shift massively between takeoff and reentry.
-- CoL of Skyfly XI is tuned for takeoff; it needs to reenter retrograde tail first or it will go into a flat spin.

Possible Improvements

Some incremental improvements are made in MoEM IX. I managed to squeeze in two additional external seats. 
MoEM IX also has dedicated LF tanks to refuel NIPS. This lowers the available delta-v of the Miner to 2034 m/s (with full crew/cargo) which should be enough. 
But refueling NIPS would still take about 12 trips. And if you make an inefficient rendezvous you are stuck in orbit because the margins are low.

So I will focus on flying the Compact Exploration System next. It should eliminate the main drawbacks like the wobbly Miner and missing lab thanks to the Mk3 form factor. I am also finalizing a new version of Valykrie Shuttle to maybe get Bobfel back. It is only sandbox, but still ...

Moho Expedition Protocol 

I followed this guide to make a low energy transfer to Moho: https://wiki.kerbalspaceprogram.com/wiki/The_annual_and_reliable_Moho_Transfer_Opportunity
Total transfer costs from 100x100 km Kerbin to 11x11 km Moho orbit: 4413 m/s (planned maneuvers)

Spoiler

- This longer route has the added benefit that the Moho arrival burn is shorter - good if you have low TWR like NIPS.
- Test was done in sandbox.
- MoEM was tanked with only 491/810 OX but full LF to maximize range of NIPS
- Total launch mass 92 tons; crewed by Bobfel Kerman, engineer; surface science cargo

- Y001D081H5M40 Took off when indicated LAN on the runway was at ~ 225°
- Headed slightly south heading 110° to match Moho inclination immediately and save delta-V
- Kept climb rate low until I reached Mach 2 to increase thrust of Rapiers

- Max speed airbreathing was 1295 m/s at 22,400 m; engaged closed cycle when I stopped accelerating

- Initial Kerbin orbit 100x100 km, inclination ~16.4° with LAN 220°; delta-V remaining in Skyfly XI = 316 m/s 
- Y001D081H5M50 First periapsis kick with Skyfly: 270 m/s

- Y001D081H5M52 Undock MoEM and NIPS; indicated delta-V 5843 m/s in 6 stages

- Y001D082H0M40 Second periapsis kick with NIPS: 336 m/s 2M35S

- Y001D082H2M55 Third periapsis kick with NIPS: 124 m/s 55S


- Y001D083H1M22 Transfer burn to Moho with NIPS: 1569 m/s 10M24S

- Jettison NIPS fuel tanks (3 stages) during escape burn; this is pretty sketchy due to part overlap.

- Y001D145H0M03 Match planes (very cheap with this route), ascending node 0.0° near periapsis: 18 m/s 05S

- Y001D179H3M35 Near sun periapsis - lower the apoapsis, rendevouz with Moho on next orbit: 687 m/s 3M47S
- I messed this maneuver up with Moho periapsis at 59 km, but on the wrong side of Moho


- Y001D353H5M24 Enter Moho orbit 429x39 km with remaining LF in NIPS: 1370 m/s 6M36S


- Short capture burn is an advantage of this route
- Due to my earlier error I am now in retrograde orbit with inclination 173.5° 

- Y001D354H0M48 Lowered Moho orbit to 38x11 km with NIPS; transfered excess LF from MoEM to NIPS;
- Delta-V remaining in low Moho orbit: NIPS 128 LF = 372 m/s; MoEM 414 LF + 491 OX = 1808 m/s; total 2181 m/s
- Y001D354H1M01 Lowered Moho orbit to 11x11 km with NIPS; 19 m/s
- Total transfer costs from 100x100 km Kerbin to 11x11 km Moho orbit: 4413 m/s (planned maneuvers);


- Y001D354H1M08 Landed MoEM without NIPS (3rd attempt); 1200 m/s used in landing.


- I tried to land with NIPS attached, but it is just to top heavy even if you find a nice flat spot.
- Even the MoEM itself likes to topple over, leave SAS on; refueling will move the CoM upwards.




- Y001D0357H0M56 MoEM fully refueled by ISRU with 5* engineer (662 LF, 810 OX and 75 Ore); 

- It will take a long time to refuel NIPS; leave some OX and ore on the surface
- Y001D0357H1M10 Jettison all ore; drain OX so that 2000 m/s are indicated;

- Y001D0357H1M22 Not enough OX to land again because I made inefficient rendezvous with NIPS; 517 m/s left

- Y001D0362H4M54 Reload; Test with full ore/OX: MoEM VIII back in 13x7 km orbit; 1598 m/s of 2416 m/s left;

Edited September 18, 2023 by Duke MelTdoWn

[miklkit]

I have a completely different philosophy.  LKO means nothing.  The minimum is Minmus.  Once refueled there, then most places are open.  And what takes off from the KSC is what lands, well, back on Kerbin.  :0)  This is my latest MK2 design.  It's main feature is the old style cabin as I have been using the inline cabin for years.  Other than that it is typical of MK2s with the ability to carry passengers and some cargo long distances.

 

How do they refuel?  Here is a fuel truck refueling a mobile science lab on Bop.  They are scattered all over the Kerbol system and are rocket driven.

This is a fuel truck lifting off and headed for Moho.

Oh, and thank you for that link to the Moho transfer window.   I have lots of trouble getting there safely.

Edited September 14, 2023 by miklkit

[MaverickSawyer]

Some really old stuff, but useful payload nonetheless...

Some vintage spaceplane shenanigans to deliver a solar-electric debris removal tug to orbit.

[miklkit]

Cool stuff.  I use MK2s for passenger and light cargo, mostly spare parts delivery.  This one is carrying an engineer and some parts he needs to install onto a mobile science lab on Moho.

Taking off from Minmus after refueling.

Landing

refueling for the trip home

This particular one has good range but is poorly balanced and hard to fly.  Still working on its replacement.