D.A.T.T. : Direct Ascent To Tylo

[Noah Foloni]

Ever since the creation of the kerbal space program, kerbals have wondered: can you preform a direct ascent mission to tylo?

TODAY WE FIND OUT!

RULES:

1: it MUST be a direct ascent mission meaning no landers or orbital assembly

2: you must bring at least 3 kerbals

3: No using mods such as NFP or Kerbal Atomics because they add cheaty engines

4: No warp drives or kraken drives

5: no using cheats to set orbits, refuel crafts, or move tylo

and finally: 6: NO. REFUELING.

New rule, number 7: No gravity assists

any missions before 09:06 AM CDT are still accepted

happy flight!

TOP SUBMISSIONS

1: camajou, for his mission having only 30 tons!

2: N/A

3: N/A

4: N/A

5: N/A

6: N/A

7: N/A

8: N/A

9: N/A

10: N/A

Still no badge

Edited August 2, 2021 by DaBakonAder

[camacju]

Direct ascent Jool-5 has been done before - direct to Tylo should be pretty simple in comparison.

Are gravity assists allowed?

[Noah Foloni]

No.

I should probably add that

[camacju]

Does "no orbital assembly" mean no rendezvous or docking at all? For example would this preclude an Apollo style mission?

[vyznev]

If you did add a "no gravity assists" rule, would that rule out braking at Jool periapsis? What about multiple passes through Tylo's SOI to slow down?

(I assume Laythe assists would definitely be ruled out.)

[Bej Kerman]

13 minutes ago, vyznev said:

would that rule out braking at Jool periapsis?

The oberth effect is a completely different phenomenon.  

13 minutes ago, vyznev said:

What about multiple passes through Tylo's SOI to slow down?

It was not said that gravity assists are allowed.

Edited July 31, 2021 by Bej Kerman

[camacju]

This challenge was pretty fun.

SSTO carrier plane brings the Tylo lander suborbital over Tylo. Upper stage of Tylo lander serves as return module. Seats 3. Overall mass 34.4 tons and could be a good deal lighter. Probably 25-27 tons possible just iterating on this design.

Journey to Tylo

Spoiler

On runway

Picking up speed in the lower atmosphere

Leveling off at 21 km

Nuclear engine turns on

Pushing to orbit

Circularizing

Jool transfer burn - split into multiple parts

Finishing transfer burn

Correction burn

Tylo capture

Deorbiting

I can't land with the nuclear engine - TWR is too low - but I can at least squeeze as much speed out of it as possible. Obviously not the most efficient but that fuel would be wasted anyway.

Descent stage finishes the job

Three kerbals landed on Tylo

Back to Kerbin

Spoiler

Ascent stage has two drop tanks

First tank gone

Second tank gone, push to orbit

I was planning on using Laythe and Tylo assists to get back home. That won't work. Luckily I have just enough fuel to do a direct transfer.

Back at Kerbin - 3 m/s left!

Aerobraking

Parachuting down

Group picture

 

Edited July 31, 2021 by camacju

[camacju]

update: just by removing extra fuel I got it to 29 tons. If you permit gravity assists I can reduce the needed mass by a lot but under 30 tons is still pretty good for a direct Tylo mission with no ions

[Noah Foloni]

That is cool.

[Pds314]

Hmm... How hard would full reuseability be? Without nukes, jets and ions it could be very very tough I think. Delta V to go from suborbital Tylo to the ground back to orbit and back to Kerbin isn't small.

Edited August 12, 2021 by Pds314

[camacju]

10 hours ago, Pds314 said:

Hmm... How hard would full reuseability be? Without nukes, jets and ions it could be very very tough I think. Delta V to go from suborbital Tylo to the ground back to orbit and back to Kerbin isn't small.

Without nukes it's hard but not impossible. Tylo orbital velocity is 2100 m/s, so let's generously say it takes 2250 m/s to land and to reorbit.

The descent stage would have to get suborbital and burn back to orbit, leaving the lander to do the rest of the landing and go back to Tylo orbit, then both halves would need to do the 800 m/s escape burn and get home.

Let's assume that the descent stage and lander have the same amount of delta-v, just for the sake of argument. Then, if the descent stage gives X m/s before burning back to orbit, it does 2X+800 and the lander does 5300-X. In other words, each stage should have 3800 m/s of delta-v, and the descent stage should give 1500 m/s worth of assistance before burning back to orbit.

Here's an example of that. (Granted, this only seats one kerbal, but just scale it up if that's the problem)

Not too hard to get into Tylo orbit.

Here's another, with less TWR but more delta-v and less mass:

 

[Pds314]

5 hours ago, camacju said:

Without nukes it's hard but not impossible. Tylo orbital velocity is 2100 m/s, so let's generously say it takes 2250 m/s to land and to reorbit.

The descent stage would have to get suborbital and burn back to orbit, leaving the lander to do the rest of the landing and go back to Tylo orbit, then both halves would need to do the 800 m/s escape burn and get home.

Let's assume that the descent stage and lander have the same amount of delta-v, just for the sake of argument. Then, if the descent stage gives X m/s before burning back to orbit, it does 2X+800 and the lander does 5300-X. In other words, each stage should have 3800 m/s of delta-v, and the descent stage should give 1500 m/s worth of assistance before burning back to orbit.

Here's an example of that. (Granted, this only seats one kerbal, but just scale it up if that's the problem)

Not too hard to get into Tylo orbit.

Here's another, with less TWR but more delta-v and less mass:

 

*Proceeds to spend 2750 m/s just to land....

Managed to optimize it down to 2550 but still... low TWR landings are not easy lol

Edited August 13, 2021 by Pds314

[Pds314]

12 hours ago, camacju said:

Without nukes it's hard but not impossible. Tylo orbital velocity is 2100 m/s, so let's generously say it takes 2250 m/s to land and to reorbit.

The descent stage would have to get suborbital and burn back to orbit, leaving the lander to do the rest of the landing and go back to Tylo orbit, then both halves would need to do the 800 m/s escape burn and get home.

Let's assume that the descent stage and lander have the same amount of delta-v, just for the sake of argument. Then, if the descent stage gives X m/s before burning back to orbit, it does 2X+800 and the lander does 5300-X. In other words, each stage should have 3800 m/s of delta-v, and the descent stage should give 1500 m/s worth of assistance before burning back to orbit.

Here's an example of that. (Granted, this only seats one kerbal, but just scale it up if that's the problem)

Not too hard to get into Tylo orbit.

Here's another, with less TWR but more delta-v and less mass:

 

I like the idea although it sounds hard to fly because you're gonna need to do a Tylo landing while you burn to orbit. I guess if you just set it on its course and focus on the landing it wouldn't be *that* bad?

Also won't it need a relay if comm network is on? I guess I could put one on whatever transfer stage brought me there though.

In any case, I almost wonder if having the lower stage do the Tylo landing itself and then burn back to orbit would work better. Sure, that means the lower stage needs more Delta-V, but it's not carrying a payload with most of that Delta-V. It would be heavier but vastly simpler to execute.

EDIT:  from a mass perspective, it's quite clearly a losing battle. Like, not even close. Even with my 6-Kerbal, 1-tonne reentry vehicle on there the mass difference between the two is impressive, and it's not even 15% lighter than a single stage design.

Also not sure the viability of 3800 / stage. Even if I accept 2250 as achievable, which with my TWR I doubt it, 800 will just about get out of Tylo SOI. It takes 890 in a single burn to leave Jool SOI and a full 1090 if I do a single burn to get back to Kerbin. So... the idea of a 5300 Delta-V trip from Tylo orbit to Tylo surface to Tylo orbit to Kerbin, by any method, does not look realistic to me. More like 5600 with a TWR in line with Camacju's idea or somewhere around 6000 with minimal TWR.

So far, if I stick a perfect landing, and I mean I run out of vertical and horizontal velocity simultaneously at ground level, I can 2550 on the way down. I think the big Delta-V killer is that I'm having about 37 or 38 degrees of cosine losses for a lot of descent.

But currently, yeah, 10 km orbit to ground to 25 km orbit costs me a total of 4950 DV. And while 950 might be enough to get back to Kerbin, it's definitely not enough without gravity assists somewhere in there, either from other Joolian moons or Dres or Duna or something. So I think 5900 is actually too little DV for a starting TWR of 0.7.

Edited August 13, 2021 by Pds314