Space Tourism Bully Market (A Finance Challenge)

[ralanboyle]

Space Tourism is alive and well on Kerbin! Unfortunately for you, lots of us are vying for the green guy’s greenbacks.

The bottom line:

Take tourists to the surface of celestial bodies as cheaply as possible.

Pricing is calculated per ticket and adjusted based on spacecraft recovery and refurbishment.

The broad strokes:

The market is fiercely competitive so your tickets will be sold “at cost.” KSP does not take refurbishment into consideration, but we will since that is a huge part of space travel. (Formula below)

There will be separate leaderboards for each destination that people submit. I expect more people will submit missions to Mun and Minmus than Tylo and Eve. In order to reduce the grindiness of submitting several ticket prices: If your ship can obviously land at other locations which require less dV and have less gravity then you can submit the pricing based on the accomplished mission. For example: If you land on Duna, that ship could have landed on Minmus, so you can note this and count the pricing toward both Minmus and Duna. Obviously, this is not going to be the cheapest way to get to Minmus, but it is an option.  dV will be based on a dV map; if you want to get fancy with gravity assists, you'll have to actually accomplish the mission. If you require refueling, your ship must have the appropriate comms/power to refuel at each location you submit. 

Yes, your tourists have to return home safely.  

The fine print:

Missions need to be run in Career mode and include the starting cost and recovery earnings. Due to the in-game recovery calculation, which is based on distance from KSC, you need to run this in career mode. If you really want to use sandbox mode, I’ll allow it if you land all stages back at KSC and provide adequate documentation to support your calculations.

All kerbals must travel inside cabins. No Command Seats.

Your spacecraft will be piloted. The pilot is not a paying passenger so subtract 1 from the total number of seats aboard. Your tourists don’t want to fly on a probe. If you are going to refuel or repack parachutes you must take an engineer (2 seats are now filled with crew). 

Processed resources do not count toward recovery cost. For example, you can't mine and process 100T of Monoprop on Minmus and return it for a profit. If you mine for fuel, you have to use that fuel. 

Airplanes using jet engines require much less refurbishment than rockets, so you can count the full amount shown at recovery if the craft being recovered has only jet engines or electric motors. If the craft has rocket engines, nukes or ion drives (or RAPIERs in closed cycle mode) then your recovery earning is cut in half (50%) to cover the cost of refurbishing the craft. Do not exploit this by decoupling rocket engines for no reason. I am not making a specific rule about when you can or can't decouple stages because I want you to have freedom to be creative. However, the community will recognize the exploit if you fly a hybrid spacecraft, then stage off your rockets for no real reason.  I'll make a rule if this gets to be a problem. 

No part mods or physics mods allowed. DLC is fine. Part clipping within reason is fine but don't go stacking tanks in tanks in tanks...

The cost of your ticket is: The cost of the launched craft (L) minus the recovery earnings (R) divided by the number of tickets sold (T). So (L-R)/T Remember, that R needs to be divided by 2 before calculating ticket price if it uses rockets. If you are recovering stages separately then find the sum of the recovery earnings for all landed stages, then subtract it from L, then divide by T.  

Missions need to be well documented. At a minimum, we need to see the craft with costs in the VAB/SPH, enroute, landed, at recovery, recovery cost screen. 

Don't use @vyznev's silly SSTO loophole with a "base" that sits on the runway. For that matter, don't spend your time looking for loopholes, just make an awesome ship. 

 

I will make leaderboards as ticket prices are published.  Come run me out of business, competition is good!

-Single Destination Tickets-

Mun:

$414 @camacju

$770 ralanboyle

$3,099 @RoninFrog

Minmus:

$414 @camacju

$770 ralanboyle

Duna: 

$6,661 ralanboyle  

$7,373 @camacju

Ike: 

$7,373 @camacju

Bop:

$3,571 @camacju

Pol: 

$3,571 @camacju

 

 

-Multi-Destination Tickets- (ISRU Not Allowed)

Bop-Pol-Minmus:

$3,571 @camacju

Duna-Ike: 

$7,373 @camacju

Edited December 6, 2020 by ralanboyle

[vyznev]

1 hour ago, ralanboyle said:

If the craft has rocket engines, nukes or ion drives then your recovery earning is cut in half (50%) to cover the cost of refurbishing the craft.

I assume decoupling the engines after landing and recovering them separately would be cheating?

(I think something like "if your craft has ever left Kerbin's atmosphere" might be less prone to exploits and weird edge cases. Although it would allow full cost recovery for boosters if you decouple them low enough. Maybe a combination of the two criteria — i.e. "has no rockets, nukes or ions and has never left the atmosphere" — could work?)

[RoninFrog]

Also, I would suggest adding that no processed resources can be counted towards recovery costs.

[Pds314]

9 minutes ago, RoninFrog said:

Also, I would suggest adding that no processed resources can be counted towards recovery costs.

Yeah otherwise you can make a profit by doing ISRU monoprop.

Interesting. So I guess the rules kind of encourage air launch to orbit. I've been practicing unguided air launches of sounding rockets for RP-1 so I think I might try that but stock and to the Mun.

Edited November 14, 2020 by Pds314

[ralanboyle]

Alright guys, thanks for the feedback. I've outlawed mined resource recovery. I have addressed the decoupling issue without making a hard rule. I really hate stifling creativity, but you are right about the exploit.  If somebody wants to launch a suborbital jet, they could potentially decouple a lander outside the atmosphere and I want to leave options like that open. Or whatever other things I haven't thought of. 

Edited November 14, 2020 by ralanboyle

[Pds314]

Hmm... I suppose PRE is probably a physics mod, which makes controlling the rocket stage of an airlaunch vehicle a bit of a mess, as switching to it can cause the plane to be terminated if it's below 23 km.

[ralanboyle]

15 minutes ago, Pds314 said:

Hmm... I suppose PRE is probably a physics mod, which makes controlling the rocket stage of an airlaunch vehicle a bit of a mess, as switching to it can cause the plane to be terminated if it's below 23 km.

Yeah, if you plan to air launch, you'll need to do it high, probably suborbital. I know that is limiting but I don't want to go down the massive mod rabbit hole. 

The refurbishment cost isn't necessarily supposed to encourage air launching. It is mostly to discourage massive SSTOs, which would clearly dominate. 

[vyznev]

7 hours ago, ralanboyle said:

Yeah, if you plan to air launch, you'll need to do it high, probably suborbital. I know that is limiting but I don't want to go down the massive mod rabbit hole. 

The refurbishment cost isn't necessarily supposed to encourage air launching. It is mostly to discourage massive SSTOs, which would clearly dominate. 

It does rather encourage air launching, though. Alas, the way you've phrased the updated rules, I guess my original plan of circularizing at 69 km before decoupling and landing the first stage is not going to work. At least not unless you'll buy the argument that Rapiers are still jet engines even if used in closed-cycle mode, which I certainly wouldn't buy myself. 

But I did manage to come up with an alternative cost-saving trick that should work under the rules as written, and might even be more efficient. Maybe. Not sure how much I should spoil it yet, since I might actually have time to fly a test mission. But let me just note that drop tanks also don't have rocket engines. And that there's actually quite a lot of things besides just tanks that you can toss on a return trajectory to Kerbin once you no longer need them. 

(Alternatively, and just staying firmly within the presumably intended spirit of the rules, I suppose ballistic air launch should work. Basically, go as high and fast as you can with air-breathers, point your nose up at a suitable angle, fire up the rockets on the next stage and decouple it off without switching to it. Just make sure it's aerodynamically stable. By the time it leaves physics range, it should hopefully have enough velocity that you can quickly land the first stage before the second stage has reached apoapsis. And if you get the launch angle right, you might even end up in a fairly reasonable orbit after circularization.)

Edited November 15, 2020 by vyznev

[Pds314]

52 minutes ago, vyznev said:

It does rather encourage air launching, though. Alas, the way you've phrased the updated rules, I guess my original plan of circularizing at 69 km before decoupling and landing the first stage is not going to work. At least not unless you'll buy the argument that Rapiers are still jet engines even if used in closed-cycle mode, which I certainly wouldn't buy myself. 

But I did manage to come up with an alternative cost-saving trick that should work under the rules as written, and might even be more efficient. Maybe. Not sure how much I should spoil it yet, since I might actually have time to fly a test mission. But let me just note that drop tanks also don't have rocket engines. And that there's actually quite a lot of things besides just tanks that you can toss on a return trajectory to Kerbin once you no longer need them. 

(Alternatively, and just staying firmly within the presumably intended spirit of the rules, I suppose ballistic air launch should work. Basically, go as high and fast as you can with air-breathers, point your nose up at a suitable angle, fire up the rockets on the next stage and decouple it off without switching to it. Just make sure it's aerodynamically stable. By the time it leaves physics range, it should hopefully have enough velocity that you can quickly land the first stage before the second stage has reached apoapsis. And if you get the launch angle right, you might even end up in a fairly reasonable orbit after circularization.)

I've been thinking through this and I think maybe the key is to avoid heading back to the KSC at all and just drop the plane in whatever terrain you're in, then have the plane take off again and RTB once you're in a stable orbit. That, or head a few hundred km east before doing a 180 to actually launch, so you end up being able to keep your attention on the plane for a few minutes while landing it at the KSC.

Edited November 15, 2020 by Pds314

[ralanboyle]

Alright guys, 

I made two changes to the rules. They are now in the OP. 

1. If you are going to refuel or repack chutes, you need to take an engineer (crew of 2). 

2. You can submit a craft for multiple destinations without actually flying it to multiple locations. Just show the math. Details in the OP. 

 

To get us started, here is a baseline run to Duna. It carries 16 tourists, has a net cost of 106,584, for a single ticket price of 6,661.  

 

Edited November 16, 2020 by ralanboyle

[ralanboyle]

Okay, 

I sent 17 Tourists to Mun for $3,037.  

Come on, somebody give me a run for my money... badaboom? 

 

[camacju]

Dang, I was gonna put in my entry in the Mun And Back Cheapskate Challenge, but then I looked a bit closer at the rules.

I'll try to do something I guess

[ralanboyle]

23 minutes ago, camacju said:

Dang, I was gonna put in my entry in the Mun And Back Cheapskate Challenge, but then I looked a bit closer at the rules.

I'll try to do something I guess

Yeah, I made enough changes to this that the ships y'all have built for other "cheap challenges" won't work. 

[camacju]

@ralanboyle ok here is my submission. You're right that other ships built for cheap challenges won't work. However, just like in many other challenges where reusability is allowed, a SSTO and a lander will be pretty good at reducing cost.

Launcher is a Mk2 SSTO. The four rapiers would be overkill but Mk2 cargo bays have a ridiculous amount of drag so the rapiers are actually needed to exceed the speed of sound.

Even with four rapiers this craft accelerates more slowly than it should. The three Mk2 cargo bays are the three highest drag parts on the craft. This is why I prefer Mk1 planes.

Additionally I only get up to 1560 m/s on the air breathing cycle of the rapiers. Normally I can get to 1650+

The plane pushes to orbit

Once in orbit, the cargo is dropped off, and I aim for the KSC

Approach to KSC

Touched down

Landed - 1500 funds worth of fuel used. Since the only engines are four rapiers I can get 100% recoverability

Minmus transfer. I couldn't get a Mun assist to work for some reason, but I have enough fuel regardless

Minmus orbital insertion

Landing burn

Landed on Minmus - this lander has four seats

Minmus ascent

Reunited with the fuel tank

I do a few aerobraking passes because KSC isn't in the right place to directly land

Aiming for KSC after a plane change

Parachutes deployed

469 funds of fuel used on the lander. I brought the fuel tank back too

In total, 1969 funds worth of fuel were used. This was definitely planned. The only engines used were rapiers which can be easily refurbished. The cost per ticket works out to 492.25 funds per kerbal

Edited November 17, 2020 by camacju

[ralanboyle]

16 minutes ago, camacju said:

@ralanboyle ok here is my submission. You're right that other ships built for cheap challenges won't work. However, just like in many other challenges where reusability is allowed, a SSTO and a lander will be pretty good at reducing cost.

Launcher is a Mk2 SSTO. The four rapiers would be overkill but Mk2 cargo bays have a ridiculous amount of drag so the rapiers are actually needed to exceed the speed of sound.

Even with four rapiers this craft accelerates more slowly than it should. The three Mk2 cargo bays are the three highest drag parts on the craft. This is why I prefer Mk1 planes.

Additionally I only get up to 1560 m/s on the air breathing cycle of the rapiers. Normally I can get to 1650+

The plane pushes to orbit

Once in orbit, the cargo is dropped off, and I aim for the KSC

Approach to KSC

Touched down

Landed - 1500 funds worth of fuel used. Since the only engines are four rapiers I can get 100% recoverability

Minmus transfer. I couldn't get a Mun assist to work for some reason, but I have enough fuel regardless

Minmus orbital insertion

Landing burn

Landed on Minmus - this lander has four seats

Minmus ascent

Reunited with the fuel tank

I do a few aerobraking passes because KSC isn't in the right place to directly land

Aiming for KSC after a plane change

Parachutes deployed

469 funds of fuel used on the lander. I brought the fuel tank back too

In total, 1969 funds worth of fuel were used. This was definitely planned. The only engines used were rapiers which can be easily refurbished. The cost per ticket works out to 492.25 funds per kerbal

Nice mission, unfortunately you have overlooked the refurbishment cost outlined in the rules. Both your SSTO and lander use closed cycle engines so your recovered cost must be divided by two. Since you landed both stages at KSC we can just look at your ship in the hanger to get the total cost, and again without fuel to get the cost when empty. Also, correct me if I am wrong but I believe used parachutes are less valuable, so there is cost there. 

I specifically made the "refurbishment" rule to balance against SSTOs. 

[camacju]

Not gonna lie I was hoping that using only rapiers would get some lateral thinking points. Alright, I'll redo the mission tomorrow

[ralanboyle]

5 minutes ago, camacju said:

Not gonna lie I was hoping that using only rapiers would get some lateral thinking points. Alright, I'll redo the mission tomorrow

Yeah yeah, if you want to put that ship on a suborbital trajectory and never close the cycle, I'll give it to you. Once you close cycle, its a rocket. 

[camacju]

@ralanboyle If a craft has RCS and no other engines, can it still be refurbished as long as I don't use the Puff engine? If not, I'll just use ion engines to do the same thing

Edited November 17, 2020 by camacju

[ralanboyle]

7 hours ago, camacju said:

@ralanboyle If a craft has RCS and no other engines, can it still be refurbished as long as I don't use the Puff engine? If not, I'll just use ion engines to do the same thing

If RCS thrusters are used as propulsion they will be awarded the same penalty as all other closed cycle thrusters. Also note, ion drives are listed in the same restriction above. While I appreciate your creativity, the whole point of the restriction is to limit the bias that KSP has toward large/expensive ships.  

The challenge is not to find loopholes in the rules, it is to get tourists to and from their destination cheaply while accounting for a reasonable spacecraft refurbishment cost. Keep in mind (IRL), to date the only manned orbital spacecraft to ever be reused is the Shuttle, which cost more to refurbish than it cost to build.  I left the possibility for you to air-launch from an airbreathing plane because it can be reasonably assumed that the launch vehicle would not need to be completely refurbished after each launch (Pegasus/Virgin Orbit /WhiteKnight). 

[camacju]

Whoops, I must have misinterpreted what you meant by "ion engines"

[camacju]

@ralanboyle Okay, new submission.

Craft is 38683 funds in SPH. Consists of three parts: airbreathing booster, orbital tug, and lander

This craft can get so much more out of the air breathing cycle on the rapier engines. As a result I barely need any rocket fuel to make orbit

Tug pushes to orbit while air breathing booster turns around

26368 funds back from this - 12315 remaining

Minmus transfer

Bonus Mun flyby thrown in for free

Minmus insertion - the tug flies past

Setting up Mun assist

Aiming for KSC after a few aerobraking passes

Landed at KSC

6713 funds recovered - divide this by 2 - net expenses are 8958 funds now

Minmus landing - we should have more than enough to get home here

Mun assist

Due to some aerodynamic trickery on the lander it actually performs quite well as a lifting body. I'm aiming for the runway here

Eh, close enough, especially for not having any lifting surfaces

4654 funds recovered - ending up with a net total expense of 6631 funds. There are four seats in this mission, making the ticket price 1657 funds each.

 

I've noticed a few opportunities for improvement as well.
-Use cheaper parts - I pick parts for optimizing mass by reflex, but since rocket fuel is so much cheaper than the loss of cost from refurbishing, this actually isn't worth it

-Take a more efficient path to Minmus - with proper gravity assists it only takes 840-ish m/s to actually get there

-Land closer to the runway - parts landed on the runway get a higher recovery value than parts landed off the runway

Edited November 18, 2020 by camacju

[ralanboyle]

Great run @camacju! I double checked the math and you are correct, sir. 

Kerbals can now purchase tickets to Minmus for $1657. 

[vyznev]

Hmm, I think I just found another loophole in your rules that basically allows reducing the refurbishment penalty as low as you want, making big SSTOs competitive after all. But it's kind of a tedious one to exploit, so I'll just suggest a fix: require that all tourists must land at the target in the same vessel at the same time.

(While you're at it, consider also disallowing ore mining and conversion on Kerbin. That's a separate cheesy exploit, but it happens to synergize well with this one.)

Otherwise, one could just:

Spoiler

1. Build a vessel consisting of an SSTO attached via docking ports to a "base" consisting of a large number of passenger cabins full of tourists.
2. Launch the whole thing from the runway.
3. Undock the SSTO and launch it, leaving the base on the runway.
4. Fly the SSTO to your chosen destination and land the tourists.
5. Fly the SSTO back to Kerbin and land it near the KSC.
6. Taxi back to the base left on the runway and dock with it. Replace the previous batch of tourists with new ones waiting at the base.
7. Repeat steps 3–6 until you've flown all tourists to the destination.
8. After the final landing on Kerbin, skip step 6 and instead just recover the SSTO and the base separately.

Since the base has no engines and is sitting on the runway, you get 100% of its cost back. The SSTO will only get a 50% refund (or slightly less, if you don't bother to taxi it to the runway before recovering), but since — with sufficient patience and piloting skill — you can use the same SSTO to ferry an unlimited number of tourists back and forth just by building a bigger base, asymptotically its cost becomes negligible. Basically, you can make (L–R)/T as low as you want by increasing T (and R) while keeping L–R constant.

Of course, you'll also need to refuel the SSTO at some point during each cycle. The easy and cheesy way is to add mining and ISRU gear to the base and mine for fuel on the runway, which basically makes fuel completely free. An alternative solution, if mining for fuel on Kerbin isn't allowed, is to do the mining at the destination (or somewhere along the way) and make sure to land the SSTO on Kerbin with enough fuel to take off again. Finally, a fully non-ISRU option is to just stock the base with enough fuel for all the round-trips. This is asymptotically the least cost-effective option by far, since used fuel can't be recovered and its cost will grow in proportion to the number of tourists, but it's still pretty cheap.

 

Edited November 18, 2020 by vyznev

[camacju]

I was thinking of something similar - have a large crew cabin in orbit and shuttle passengers down two at a time

[camacju]

@ralanboylehere's a lazy mission taking one tourist to Duna and Ike, costing 7373 funds. Since the Duna landing uses 92 oxidizer and the Ike landing uses 71 oxidizer I'm going to split the cost of the Duna and Ike tickets in this 92:71 ratio, so the Duna ticket costs 4161 and the Ike landing costs 3212

Four segment craft - airbreathing booster, rocket booster, lander, fuel tank

It's vaguely comical to see a plane carrying a rocket twice its size

Same as before, rocket pushes to orbit and booster turns around

It always takes way too long to turn around in the thin layers of atmosphere

Rapiers get the most distance per fuel at high speed so it's actually advantageous to punch the throttle and glide to target

I totally didn't almost lose control here

28528 back

Circularizing

Booster aims for KSC

I can never get the thing to land exactly on the runway for higher recovery value

2420 back

Duna transfer, Ike assist drops periapsis down to aerobraking level

Course correction

Aerobraking

Lander leaves tug in orbit by undocking, which pushes it below 50 km - so I can deorbit for free

Due to aerodynamic trickery, the lander has much higher drag facing backward than facing forward. So it's hard to fly but saves a lot of dV on landing and ascent

Ascent

Rendezvous

At this point I realized I way overengineered this thing so I take it to Ike

Ike insertion

Ike landing

Rendezvous

Pulling orbit below Ike - wait for optimal transfer window since I'm lazy and neglected to time the return burn correctly

Return burn is small

After an outsize course correction and a relatively small one, I aerobrake

Pulling periapsis out of atmosphere

Aiming for KSC

Parachuting down

Final recovery