[Stock] [1.05] Hurricane Launch Vehicle Family

[Majorjim!]

Just now, sgt_flyer said:

i guess he's talking about this addon that creates multiple save points when you drop a recoverable stage, so you can switch between saves to control each part

http://forum.kerbalspaceprogram.com/index.php?/topic/72605-105-flight-manager-for-reusable-stages-fmrs-v1001/

That sounds rather unsatisfying.. Thanks though!

Edited December 28, 2015 by Majorjim

[Rune]

9 minutes ago, Majorjim said:

That sounds rather unsatisfying.. Thanks though!

Yup, it's a mod, but IMO it's not that drastic of a mod. After all, all it does is savefile magic that you could do yourself with the notepad, and I have done myself... as easy as quicksaving just after separation, flying the booster back, noting how much you recover, then loading back to the main ship, carrying on, and later adding the previously written down booster recovery funds. If you want to fully stock version of the hack, but the mod is fancier and faster, since it copies full landed vessels and it does so automatically.

 

Rune. Then again, for a career save, a SSTO is about 5x more convenient.

[DMSP]

10 hours ago, Temstar said:

Could you describe a bit the parameters around this reentry? Most important numbers are your AoA, original orbit, deorbit burn delta-V and SAS setting.

Well, SAS was on, and the angle of attack was varied greatly as it was tumbling. The whole booster was essentially pointed at the "North" marker at 0 degrees when it broke up, which makes sense, because of Gs and everything.

It took about 230 m/s to de-orbit the booster. I was about at a 102x108 orbit.

10 hours ago, Temstar said:

I usually just set AoA to 40 degrees and put SAS on hold heading, turn on fine control and just make minor adjustment to AoA to keep it between 30-40 degree range and then wait till around 1300m/s before i transition to level fight.

Alright, I'll try that on Flight 2.

10 hours ago, Temstar said:

Oh another thing, if you are reentering with fuel remaining, pump the fuel to the middle of the craft, say the adapter between 3.75m tank and mark 3 tank. Generally if you have fuel left it will be at the most rearward tank and that will upset the CoM too much. Since the craft is already tail heavy as there's nothing heavy in the nose to counter balance the extremely heavy engine it wants to flip in the air. Having the CoM a fair bit in front of CoL allows control surfaces to counteract this tendency to flip but if you upset the CoM by having fuel in the rear then you run the risk of aerodynamic forces overpowering the control surface's ability to keep it straight.

Yeah that's exactly what happened, I had like 1/20 fuel left, and of course (Due to KSP fuel draining) it was in the back.

That explains why I couldn't get the nose down.

These tips will help me get Flight 2 and Flight 3 down to the ground.

 

Again, great craft.

[Temstar]

Oh god it actually works, you can indeed fly a plane with its ass missing:







Those shielded docking ports have outrageously high max temperature. And yes the superfluous extra nose landing gear has been fixed.

Edited December 30, 2015 by Temstar

[Temstar]

Hurricane Duo Block II was always intended as a intern solution intended as a test of economics for a fully reusable vehicle. The excellent cost per ton figure it was achieving shows that despite the ET being much cheaper than the Auroras, recovering them still improved the economics noticeably. However the parachute recovery was not a workable long term solution - its incredibly fiddly to setup and it did not achieve high enough accuracy being a purely ballistic return craft. A better solution is needed...

I give you: the Block III:



The ascent part of the vehicle still flies the same so I won't bore you with too much details on that, refer to the first post for ascent flight. Instead let's look at the interesting part of Block III, the ET recovery:
 

Spoiler

As with Block I and Block II, the External Tank's service bay houses a fuel tank disabled at launch for the purpose of reentry. Once the ET separates from the Aurora boosters you will want to switch this on to allow reentry burn. For the Block III the deorbit fuel tank size has been increased to give the operator about 140-150 m/s of delta-V, which I feel strikes a good balance between high accuracy and not eating into the payload too much. In addition you might have noticed the much larger Z-1k battery also inside the service bay and many more 24-77 Twitch engines than previously. These are all intended to make accuracy deorbit burn easier, and since the ET is now fully recoverable we can afford to spend a bit more money on the ET hardware. The deorbit tank has some spare tankage left - you may want to fill it up entirely if you prefer bigger deorbit burns or want to deorbit from higher orbit.


The other thing you want to do before deorbit is change the ET's navball orientation. Since the ET needs to ascent tail first in rocket mode, it's lone probe core is facing the wrong direction when you want to fly the ET as a spaceplane. Rather than adding another probe core facing the other way I've used a shielded docking port on the bottom. Besides giving you the "Control from Here" option that allow you to fly the ET like a plane the shielded docking port also work as an excellent nose cone as it has extremely high max temperature. Also in the event that you mess up the gravity turn and end up in orbit without enough fuel to deorbit the components of the Hurricane you can send up a small tanker to dock with the ET's docking port to transfer fuel.


ET performing deorbit burn.


Trajectory after deobit burn. Having done a lot of deorbit and landing now with ET and Aurora I now recommend you aim the pure ballistic trajectory's impact point close to KSC. In an overshoot like this case don't worry - overshoot is easy to compensate for, just keep the vehicle in high AoA for longer than normal and use your airbrakes liberally.


Peak heat load during ET high alpha reentry. Notice how the hottest temperate has plenty of buffer space thanks to both the large AoA and the extremely heat resistant shielded docking port.


ET approaching KSC. The ET is much easier to fly than Aurora which have to fight against CGCP mismatch caused by that heavy engine in the back. The ET's CoM is much closer to the centre of the vehicle which makes it easier to handle, and the missing back end doesn't seem to cause any real problems.


ET flaring just before touch down.


ET stopped on the runway, ready to be recovered.


Here's a Hurricane Duo's ET tank ready to be recovered on the runway.

The craft files are in the first post.

[Warzouz]

On 27/12/2015 at 1:23 PM, Temstar said:

...

Yeah true enough, but I suppose generally when people think SSTO reusable rocket they expect the entire rocket to come back in one unit as well. That's certainly doable but if you want that kind of reusable SSTO to also have precision landing capability AND be able to scale the design up and down then it becomes really difficult.

...

I don't belive so. Reusable SSTO rockets are very easy to scale up because they have a very simple design. Basically, there is no staging until LKO.

I play a lot with SSTO rockets (check my Cygnus family launchers), once you get one rocket to go to LKO, it's simply a matter of adding engines and fuel. I managed to go from 15T to 600tons with regular steps, only by adding or switiching engines and adding fuel tanks. For example I did the 600T variant in 10 minutes from the 300 tons rocket. First try : success.

For landing, recover price is very dependent on where you land/spash. Sure I rarely land on KSC (98%) but I usually splash down near it (20 to 70km) and get 97% of dry cost. I remembered I messed up once and got only 90%. Renentry is mostly always the same : deorbit on the crater for 60m/s and wait (chutes are automatic). a small burn is needed to avoid breaking expensive stuff as engines... You need to practice few times to understand where to deorbit. That's the only constraint.

My price per ton goes from 360 to 490 funds/ton including average recovery loss.

Your ship disign is very nice though but your part number is very high (I'm figthing to keep is very low...) and this is already a problem when I lift some very heavy payloads. The part count reduces the framerate and ascent takes forever.

Here are stats from my launchers

[Temstar]

It would be good to have the formula for recovery value curve that plots distance to KSC vs recovery %. The wiki just talks about greater circle distances and so on without giving us a straight answer. Without this it's hard to do analysis.

Having done my share of tail sitter rockets I have to say I'm not too fond of this recovery method, particularly if the landing needs manual control of braking rockets. Seems to me like a lot of things can go wrong - hitting the deck too hard, landing on a slop and fall over, landing in water and fall over and so on. For tail sitters I prefer a passive safe design like this:

Where it can safely land under only parachute power without braking rockets. And that's what I mean hard to scale up since we don't have giant SpaceX style landing legs.

[Warzouz]

8 hours ago, Temstar said:

It would be good to have the formula for recovery value curve that plots distance to KSC vs recovery %. The wiki just talks about greater circle distances and so on without giving us a straight answer. Without this it's hard to do analysis.
...

Having done my share of tail sitter rockets I have to say I'm not too fond of this recovery method, particularly if the landing needs manual control of braking rockets. Seems to me like a lot of things can go wrong - hitting the deck too hard, landing on a slop and fall over, landing in water and fall over and so on. For tail sitters I prefer a passive safe design like this:
...
Where it can safely land under only parachute power without braking rockets. And that's what I mean hard to scale up since we don't have giant SpaceX style landing legs.

Yes I would like to know the recovery curve too. In any case, it's very forgiving. Extrapolating it from trials would be quite a hassle. I always land withing 70km and very rarely get less than 96%. I favour landing in water, because I fear those mountains (basically since 1.0.4, there is no way to avoid crashing into them) and water is more forgiving in 1.0.5.

But landing stuff that way is much easier than it seems. SSTO space planes are harder to land, as I also use them for very light charge and passengers. As I said, once you chose a reentry profile, you just have to figure where to deorbit.

As for powered landing, it is sort of mandatory as  the launcher is quite heavy (dry weight of the launcher is basically 80% of the payload). Landing it with chutes would require hundreds of them for my heaviest vehicle which weights 460tons (dry) for 600 tons payload to LKO.

Power landing is quite easy, especially since water is more forgiving in 1.0.5. As you've noticed, I even don't use any landing gears. Less chutes, no gears, lower part count.

I don't have played 1.0.5 much. The reentry is harder than before because of overheating. Cygnus family needs some tweaking (probably 2 more drogue chutes and removing the airbrakes).

 

[Temstar]

All craft files uploaded to KerbalX now that mediafire is banned.

In other news:


I was able to use a pair of Auroras to launch a 80 ton modular space station composed of five modules in a single launch as part of a challenge. The whole craft was created under 30 minutes including both making the station as well as integrating the Auroras to it to form a launch system. Demonstrating the usefulness of the modular design.

 

Edited January 18, 2016 by Temstar

[Whovian41110]

I am having a difficult time launching the solo.  At about 1.5 km the mammoth engines go from producing about 4000 thrust to 900 thrust.  Do you know why that would happen?

[Viragos]

Thanks for the inspiration Temstar! I saw these and even though I don't have Mammoths and 3.75m stuff unlocked in my Career mode yet I was able to downscale it to run with the Twin-Boar motor on 2.5m parts. Recovers about 40k per booster which is helping the economy a ton

[NISSKEPCSIM]

Well... the westerners got to it before I did. :-) (I hope you're not Russian, like I am, 'cause that would ruin the whole joke)

[Agent Awesome]

On 27/12/2015 at 0:00 PM, Temstar said:

I don't use FMRS, but seems like a good option. However if you do use it to recover stages then it's by definition not stock

With stock I've seen three methods:

• SSTO, the whole rocket goes up on a single stage, release payload into orbit and then deorbit itself. Eg: SKRV
• two stage, where the first stage separate quite early during flight after providing a huge amount or acceleration. The upper stage coast up to above the atmosphere, during this coast you switch to the first stage and land it on Kerbin. Once it lands you immediately switch back to the 2nd stage and it will just about reach AP for the circularisation burn
• what I've done here

I'm planning to work on making the ET for Dual and Trio recoverable, shouldn't be very hard. Although I don't think it will make the economics much better as the empty ET is worth very little.

I'm planning an SSTO rocket series that is a combination of the hurricane and skrv 

its still w.i.p