[STOCK] Kerbal Dynamics: Dragon 9 Hard Deck Landing

[ihtoit]

Okay, I know it says stock up there, but I will allow the flight contoller from BDArmory (to stop probe cores from physicsing out in atmosphere) and MechJeb. Everything else is strictly stock.

 

PROFILE:

Design and deploy a space launch system comprising of precisely TWO stages (SRBs permitted as a boost strap-on as long as they're fully retrievable) and a useful payload (robot probe, comsat, station part, whatever, as long as it has solar generation and battery storage and one antenna. Extra points for a multiple payload launch). The top stage forms part of the payload. Crewed payloads should also have some controllability, as in being able to choose the landing site anywhere within 20 degrees of the orbital plane.

The first stage should have the capability (demonstrate, please) of making a turnaround landing at KSC (as in, refuel, attach the payload and light the bottom).

The first stage is NOT allowed to enter orbit.

[Challenger's note: Images to follow, I have not yet managed the landing part, seems the boost stage doesn't take too well to lithobraking on the pad at Mach 3 - fuel is the problem for me, and 8 stock parachutes don't seem to do a lot with a 17 ton deadweight).

This is a Kudos challenge: great if you can demonstrate your design. Even better if you can perform a turnaround launch!

Suggested timeline:

1. Launch
2. Kick
3. MECO
4. Stage sep (<40km)
5. SEB to p.100km, SECO
6. Switch to primary stage
7. Boostback burn, deploy chutes
8. Switch back to payload
9. Orbital insertion
10. Switch back to primary
11. Landing
12. Switch back to payload, deploy.

 

Mission Badges:

 

[EDIT]

You're all going to hate me, but here's a mission extension I've not only been playing with, I've actually gone and done it.

Using your current design stock launcher, put a crewed station module in orbit and then dock a spaceplane to it.

Profile:

Spaceplane should be STOCK. MJ and BDAI permitted addons.

Station module should have an antenna, *space* available for the spaceplane crew, and at least one permanent crewmember.

Demonstration should consist of a horizontal launch (on wheels, on the runway) of your spaceplane, and successful landing of your Dragon booster.

(Pics to follow. I built and docked an X-Wing to a 35 ton science station. Tried getting a fuel tanker up there but didn't have the TWR on the top stage to make orbit).

Edited December 29, 2015 by ihtoit

[mythic_fci]

I'm testing a craft for this challenge right now. Do we need to land back at KSC, or are other locations acceptable? Anyway, I'll definitely be doing this regardless.

Edited December 23, 2015 by FCISuperGuy

[ihtoit]

1 hour ago, FCISuperGuy said:

I'm testing a craft for this challenge right now. Do we need to land back at KSC, or are other locations acceptable? Anyway, I'll definitely be doing this regardless.

If you go for a shallow launch profile (direct burn to orbit, as you would a heavy launcher), you could try for the near coast of the continent to the East, or for a (probably) more realistic boostback, the Island centre. There is an old space centre to the North West(?) but you'd have to launch retrograde for that; hauling three quarters the way round the planet, or rather for one complete orbit as MET would demand, isn't on the table. The ideal would be at KSC.

A possible extension to the challenge, if you do decide to land elsewhere, is to build a retrieval system to go fetch the stage. Quite how you'd load the stage onto the vehicle is going to be problematic without some sort of cabling system like KAS provides, tho... or you could go Manley and land it on a barge!

Something to note though, is that for the first stage, you would need half the fuel you take up on that stage for the boostback/landing. I've tried the 3m tanks with 8k fuel for ascent and 3k for return, and ran out of fuel in the descent at about 15km altitude. Chutes didn't help. Although, I have consistently managed to put the first stage on or near (<2km) the KSC launch pad (and put the second stage into 100, 150, 200 and 300km orbits on my test flights). Albeit at hypersonic speed.

Edited December 23, 2015 by ihtoit

[mythic_fci]

1 hour ago, ihtoit said:

If you go for a shallow launch profile (direct burn to orbit, as you would a heavy launcher), you could try for the near coast of the continent to the East, or for a (probably) more realistic boostback, the Island centre. There is an old space centre to the North West(?) but you'd have to launch retrograde for that; hauling three quarters the way round the planet, or rather for one complete orbit as MET would demand, isn't on the table. The ideal would be at KSC.

A possible extension to the challenge, if you do decide to land elsewhere, is to build a retrieval system to go fetch the stage. Quite how you'd load the stage onto the vehicle is going to be problematic without some sort of cabling system like KAS provides, tho... or you could go Manley and land it on a barge!

Something to note though, is that for the first stage, you would need half the fuel you take up on that stage for the boostback/landing. I've tried the 3m tanks with 8k fuel for ascent and 3k for return, and ran out of fuel in the descent at about 15km altitude. Chutes didn't help. Although, I have consistently managed to put the first stage on or near (<2km) the KSC launch pad (and put the second stage into 100, 150, 200 and 300km orbits on my test flights). Albeit at hypersonic speed.

Actually, you could use a chute/engine combo. I'm testing that, and it seems to have good results so far. My latest test flight did a long boostback burn, OVERshot the KSC, then deployed chutes and coasted down for a 10m/s landing with rocket assist. You only need a small tank for that.

[ihtoit]

All right, I've pretty much managed it!

This is what I call the Falcon 3. Actually, it's about the ninth iteration and fourteenth launch - and the first 100% mission success. 261t on the pad. Note the ridiculous number of chutes and the airbrakes. You'll see why I went overkill later.

 

SRB sep and chute deploy, they'll splash down in the sea.

 

Clean separation:

 

MECO and stage sep occurred at precisely 40km, which also happened to be the point at which the apoapse burn stopped. Handy. Also took the opportunity to jettison the shroud.

 

Payload to orbit. Simple sensor package and a bit of solar overkill because I can.

 

Back to the primary stage which since separation has been drifting in a ballistic arc. Time for that boostback burn.

 

Target difference of 70m! I could correct that with the RCS, which is what I'm doing here.

 

OK, this time I think I installed too many chutes. It threw the landing estimate off by 2km. At 5km there's nothing I can do now, since that's where I had set the chute to full deploy.

 

It did stick the water landing, and in fact remained vertical as the landing legs were touching bottom! SUCCESS! You can see the top of the VAB on the horizon off to the right, and the pad water tower - that's how close I was! Shy of 2.1km!

16 minutes ago, FCISuperGuy said:

Actually, you could use a chute/engine combo. I'm testing that, and it seems to have good results so far. My latest test flight did a long boostback burn, OVERshot the KSC, then deployed chutes and coasted down for a 10m/s landing with rocket assist. You only need a small tank for that.

I had 4k LF after MECO for the boostback/landing and actually landed with the TINIEST bit of fuel to spare!

Edited December 23, 2015 by ihtoit

[mythic_fci]

@ihtoit Great entry and beautiful vehicle! You beat me to it The boostback fuel depends on your trajectory - if you have a steep upwards trajectory, you can easily kill your lateral velocity with some fuel to spare for corrections.

Edited December 23, 2015 by FCISuperGuy

[ihtoit]

13 minutes ago, FCISuperGuy said:

@ihtoit Great entry and beautiful vehicle! You beat me to it The boostback fuel depends on your trajectory - if you have a steep upwards trajectory, you can easily kill your lateral velocity with some fuel to spare for corrections.

I admit, I MechJebbed it. Auto ascent and auto landing. I even let it do the orbit insertion.

(why can't MechJeb nail circular orbits?)

I reckon I could have put her down right on the pad if I had taken the time to do it manually, but I wanted to get some images up.

[mythic_fci]

I give up for today... The control switching's just too hard. You need to be able to switch at exactly the right time, something that KSP doesn't always allow you to do (*ahem* Can't switch in atmo *ahem*). I've tested launching it without relighting the 2nd stage for orbit, and it works - mainly because I don't have to juggle 2 spacecraft. Will try again tomorrow.

[ihtoit]

that's where BDArmory comes in handy, it allows you to switch at will, even if the engines are firing.

[prykpryk]

There is my attempt.

 

I could very easily land on top of the VAB but whatever

[ihtoit]

nice! Note to self: DEFINITELY don't trust MechJeb for landing.

 

Also: welcome to the forums!

Edited December 23, 2015 by ihtoit

[Kokanee]

Challenge badge?

 

 

[ihtoit]

yep, I can go for that  It is the Falcon 9 Challenge, but hey.

[EDIT] I changed the name of the challenge, 'cos I do love the badge.

Edited December 24, 2015 by ihtoit

[Kokanee]

Yeah sorry I did that in a hurry before leaving work, my bad.

[ihtoit]

I stuck a pad landing! With a 32t crewed payload!

(pix to follow soonish)

[Kokanee]

My development program is not quite at that level, but I did manage to land in the flat area just north of KSC, with a 0.6t communications sat as payload.

 

View album in imgur to see notes.

 

I'll have to see how much of a payload this thing can deliver to LKO; a few tons at least judging by the amount of fuel I had left over in the 1st stage. Then onto developing a heavy version to lift big things! Cool challenge.

Edited December 24, 2015 by Kokanee

[Foxster]

Love prykpryk's entry because it doesn't use SRBs and it doesn't use 'chutes. That's how it was done by SpaceX this week. It really should be a requirement here too then, or at least make other entries a "lite" option. 

Also - can someone give me the idiot's guide to using the BDArmory module to keep the first stage from disappearing?

Edited December 24, 2015 by Foxster

[ihtoit]

29 minutes ago, Foxster said:

Love prykpryk's entry because it doesn't use SRBs and it doesn't use 'chutes. That's how it was done by SpaceX this week. It really should be a requirement here too then, or at least make other entries a "lite" option. 

it's an option - in fact my early launches didn't use the SRBs, I only strapped them on to ensure I had enough fuel for a shallow-launch boostback after launching with a substantial payload. The Falcon Heavy uses strap-on boosters, that's what they'll be using for their crewed launches since we're talking 40 tons of capsule not 2 tons of comsats. Back to my early launches, this is what #1 looked like:

Yep, those are fins. No chutes, and no RCS. The second stage consists of the stage control and a nose cone. Needless to say the fins were a mistake (the stage nosed into the deck at Mach 5) and soon came off. Launch #2 had no fins and a small satellite, and 4 chutes on the first stage. Short on fuel, it did a hypersonic swan dive and clipped straight through the VAB.

[Foxster]

Here's a quick and dirty entry from me...

1st stage was fired until an Ap of 100km. Payload stage then separated and powered on to orbit insertion. Switching back to booster, it just needed a small burn to set the landing site on the peninsula east of the KSC. Landing was undramatic. 

[mythic_fci]

Second day of testing with my modified Dragon II rocket has turned up few good results. I've added some spoilers it the top of the first stage for added braking and control, and they seem to work - however, my engines burn up on reentry now. They just can't seem to withstand the heat, even with radiators. Any advice? In other news, I've tested the landing sequence without chutes, and it works great! Time to solve the engine problem...

[Kokanee]

26 minutes ago, FCISuperGuy said:

Second day of testing with my modified Dragon II rocket has turned up few good results. I've added some spoilers it the top of the first stage for added braking and control, and they seem to work - however, my engines burn up on reentry now. They just can't seem to withstand the heat, even with radiators. Any advice? In other news, I've tested the landing sequence without chutes, and it works great! Time to solve the engine problem...

Try having your 1st stage go no higher than 35km; I separate my 2nd stage once i hit 30km apoapsis, and let the 2nd stage do the rest of the work. Switching back to my 1st stage, it's normally at 25km and falling like a rock by then... But the air is thick enough that it can't build up enough velocity to generate a lot of heat. I barely get the "white" air effects.

[Dante_B]

Awsome challlenge there is my attempt.

 

https://www.youtube.com/watch?v=ILtEJDqA6AY

 

 

Craft file: http://kerbalx.com/Dante_B/Falcon9-rebuild

Edited December 24, 2015 by Dante_B

[SpaceplaneAddict]

Tests using dummy payloads are showing good results

[ihtoit]

On 12/24/2015 at 8:13 PM, Dante_B said:

Awsome challlenge there is my attempt.

 

https://www.youtube.com/watch?v=ILtEJDqA6AY

 

 

Craft file: http://kerbalx.com/Dante_B/Falcon9-rebuild

loving that! Pretty sure those antennas aren't stock, though?

[EDIT] They might be in 1.0.5, I can't find them in my 1.0.4 build.

Edited December 26, 2015 by ihtoit

[ihtoit]

15 hours ago, SpaceplaneAddict said:

Tests using dummy payloads are showing good results

how did you get that to not flip with the fins? I had to lose them because all the stage wanted to do with them on was nose down and piledrive the planet.