Project LR1 Skyhammer: A New Shuttle [p1]

[kocmolyf]

My company just had a major product launch, so I've been unable to put any time in for a while. I finally got a little opportunity today and used it to completely re-do the drop tank physics. Doing this in Orbiter is actually more complicated than it would be doing it from scratch, because it suffers from a "split brain" problem - some of the forces are handled by Orbiter, while I have to account for others myself.

Regardless, I managed to make it more legitimate. I had to abandon aerodynamic effects for the time being - I know *how* to do it, it's just more trouble than it's worth at the moment because you're not supposed to stage in the atmosphere anyway.

From here to first release, it's just a few small additions and a general review.

---------- Post added at 08:04 AM ---------- Previous post was at 03:21 AM ----------

I decided that I'd like at least a little forward progress this weekend, so I implemented the HUD alignment cues I had in mind. This makes it much easier to target your desired heading on liftoff.

Zenith compass on the pad. Currently oriented at 145 degrees.

The Shuttle tower is cleared at 150 meters altitude. By 1km the roll program is complete, heading is 90 degrees.

Beginning the gravity turn, using the zenith compass and the azimuth alignment bar to keep heading and bank as desired.

Beginning the roll to heads-up. Notice the alignment cues are linked to the direction of thrust rather than the nose heading.

 

[kocmolyf]

I closed out the last item on my list before release. I'm going to sit on it for one more day to do a sanity check on everything and write a little readme, but I expect to release the ascent prototype tomorrow!

I added numbers to the 45-degree hashes on the zenith compass.

I redid the nose area to give it less of a "double chin". The previous nosecap was extruded from the body - this time I went the other way and started from a hemisphere.

The old nose for comparison.

 

[Nicholander]

I can't wait until you release this... Even if it is just later today.

 

[kocmolyf]

I submitted it to the hangar last night - if it doesn't get approved within the next hour or so I'll post an alternate link while we wait.

---------- Post added at 07:31 PM ---------- Previous post was at 05:53 PM ----------

Prototype p1 is released! See the OP for details.

 

[Nicholander]

YES!!! Congrats on the release, though I have one thing, not really a bug, but it's just that though the readme says that autopilots will cause the spacecraft to wild pitch and yaw oscillations, when I try it the autopilots do absolutely nothing, both kill rotation and attitude MFD. And that makes it quite a bit annoying trying to get into orbit.

 

[kocmolyf]

...though I have one thing, not really a bug, but it's just that though the readme says that autopilots will cause the spacecraft to wild pitch and yaw oscillations, when I try it the autopilots do absolutely nothing...

Ah, yes, I see the readme is poorly worded. When I said that the autopilots have no control, I meant that they are *disabled*. I agree the lack of a stabilizing autopilot is irritating. I've considered adding roll and yaw damping to the default steering controller - I think you probably still want to leave pitch unlocked.

 

[Nicholander]

Oh, that's why. Thanks I guess, also, I tried launching the LR1 on an HCLV, and I guess it can be launch on the HCLV-4 Sidemount, but that's only with the LR1's 7 propellant tanks all empty. Actually I haven't tried it, but when I was trying to launch it on an HCLV-S (The XR-2 version), I emptied all the tanks (Manually, not with the "empty all tanks" button, as that causes Hyperion MFD to display it's payload weight as -1), and it says it weighs 91 tons, which is too heavy for the HCLV-S, but is fine for the HCLV-4 Sidemount. But, when I clicked the LCH (Launch) button on Hyperion MFD, the whole thing just ejected itself from the solar system. Seriously, like what happens when you enter the atmosphere at a too high time acceleration. Yeah, so that's how my attempt at launching the LR1 Skyhammer with the HCLV went. Also, here's how it looked on the launch pad:

 

[kocmolyf]

Haha. Yeah, there could be some weirdness when attached to another vehicle. I'll try it and see if I can reproduce it.

---------- Post added at 09:27 PM ---------- Previous post was at 08:55 PM ----------

Boosting on the HCLV worked for me (it didn't quite have enough propellant to complete the orbital insertion, ended up at like 120 x -180).

 

[Nicholander]

Hmm... I'll try It again and tell you what happens.

---------- Post added at 09:53 PM ---------- Previous post was at 09:33 PM ----------

It works! Maybe I was doing something wrong before, but the point is it seems to work, And I also used the HCLV-4 Sidemount instead, and was able to reach a 580 Km x 1,000 Km orbit.

EDIT: Also, when do you think you'll be done with the next update?

 

[NextBigLeap]

I don't see it on the hangar, can someone help me out?

 

[kocmolyf]

I don't see it on the hangar, can someone help me out?

It's posted on the first page.

 

[Lucy]

I submitted it to the hangar last night - if it doesn't get approved within the next hour or so I'll post an alternate link while we wait.

Addon approved, sorry for the delay. There was quite a backlog!

[ame="http://orbithangar.com/searchid.php?ID=6646"]LR1 Skyhammer[/ame]

 

[kocmolyf]

Addon approved, sorry for the delay. There was quite a backlog!

Much appreciated!

 

[Scav]

After a 9-10 month hiatus (not sure what was wrong with me at the time), I'd have to say this project has seen me warming up my Orbiter installations again. Even as this is a mockup, the two turns I've taken getting this thing up in to orbit has been fun . . .

Some thoughts:

1. Ascent information and feedback is a lot easier to work with than I thought it would be. It really kinda puts you right into the thick of what the spacecraft is doing, and makes planning your next move that much easier. I found it not very difficult to discern which way to start my roll maneuver off the pad, and my pitch maneuvering was very easy to follow.

2. I ended up placing the LR1 stack at a 335' heading on the pad given the base scenario. This allowed clearance for the port-side fin against the launch tower and seemed to allow a little more accessibility for the crew access arm (were you thinking of putting the crew access hatch at the topside of the vehicle, or more towards the side?).

3.

As for Skyhammer, I would expect it to be able to land (gently) with zero fuel and max payload.

Given this criteria (from a while ago, I know), do you think this vehicle would be a decent candidate for retrieving dead (or decommissioned) satellites either in LEO or geosynch? I've often thought that that would be a next move for my own VSA (as dead as it is right now) to try to clean up some of the space junk (or stuff that's likely to become space junk) in a series of somewhat cost-effective missions (not that any space mission is cost effective, but you understand what I mean, and I've used too many parentheses in this post already).

To sum it up: :thumbup:

 

[kocmolyf]

I'd have to say this project has seen me warming up my Orbiter installations again.

I don't think there's a better compliment.

Ascent information and feedback is a lot easier to work with than I thought it would be. It really kinda puts you right into the thick of what the spacecraft is doing, and makes planning your next move that much easier. I found it not very difficult to discern which way to start my roll maneuver off the pad, and my pitch maneuvering was very easy to follow.

I'm glad you found it useful! All of the extra HUD data is stuff I came up with while testing - things I found I really needed. They are definitely "organic" and aren't yet part of a cohesive design. Any ideas for improvement are welcome.

I ended up placing the LR1 stack at a 335' heading on the pad given the base scenario.

That is very reasonable. I think my original pad heading was 325'. I changed it because I figured the crew arm would extend straight from the tower - but the more I think about it, the payload bay should probably either face towards or away from the ramp. In any case, the Shuttle pad is the wrong pad for the Skyhammer, so most any orientation would be legal at this point.

PS if anyone is interested in modeling a pad, I would happily include it for the time being. Or just release it on the hangar in parallel if you like.

...do you think this vehicle would be a decent candidate for retrieving dead (or decommissioned) satellites either in LEO or geosynch?

I will give you a technical answer and a philosophical answer.

Technically, the Skyhammer should have no problem retrieving a satellite from LEO. It's not very different from, say, an ISS mission, assuming the altitude is not too high. Geosynchronous orbit is far outside the Skyhammer's propulsion capability, unfortunately. Its dry mass is simply way too high.

Philosophically, it probably doesn't make a lot of sense to retrieve dead or decommissioned satellites from orbit and bring them back to Earth (at least not until propellant is the majority of the mission cost). If your objective is to clear debris, a much smaller automated vehicle to rendezvous with and destructively deorbit it is probably better. If your objective is to repair and refurbish - you should probably not do it at all. Satellites are useful in orbit but they go out of date very quickly (electronic technology moves fast). I would expect that replacement is the right approach in almost all cases.

I understand that the Shuttle flew at least one set of retrieve-and-relaunch missions, but I believe those were largely politically rather than economically useful.

---------- Post added at 03:45 AM ---------- Previous post was at 03:41 AM ----------

Now that many of you have had a chance to try out this little prototype, I'd be interested in your thoughts on where to push next. Originally I had planned on doing final approach and landing as that seemed like a fun portion of flight, but I would do something else if y'all were more interested.

What would you most like to see?

1. Final approach and landing.
2. Orbital maneuvering / docking.
3. A "horizontal slice" (all other phases of flight, badly/hastily implemented).
4. Something else?

 

[MaverickSawyer]

Orbital Maneuvering should be the next phase of flight tackled. After all, you can't deorbit without being able to handle yourself on orbit! :lol:

 

[K_Jameson]

A fantastic and inspirational project.
Maybe, 40 tons to LEO in a stage-and-half manned and reusable launch vehicle is a pretty optimistic statement, but remains an excellent project.
Incidentally, the LR1 is really close to a my project for a reusable and stage-and-half launch vehicle. Even the fuel choice was the same. Main difference is the scale of the project: my project was a smaller and unmanned launch vehicle, but this demonstrates that similar problems leads to similar solutions. Here you can view my sketches:

http://orbiteritalia.forumotion.com/t2801-skunk-works

 

[kocmolyf]

Maybe, 40 tons to LEO in a stage-and-half manned and reusable launch vehicle is a pretty optimistic statement, but remains an excellent project.

I certainly agree on the manned part. I do think splitting people and cargo is a good idea, so you can optimize for each case. But this is Orbiter; combining them is just more fun.

I actually don't think 40 tonnes is that crazy. The Skyhammer stack is significantly heavier than the full Shuttle stack, and it uses a dense propellant mix with high performance. I don't claim that my back of the envelope calculations are real engineering, but I actually started with a smaller vehicle and moved up because of how potent that combination was. I would consider the mass fractions quite feasible.

Incidentally, the LR1 is really close to a my project for a reusable and stage-and-half launch vehicle.

Very cool! I always liked the over-wing tanks. Ultimately I thought the forward tank was more practical to keep the center of mass forward.

 

[Scav]

Hmm. :idea:

I'm glad you found it useful! All of the extra HUD data is stuff I came up with while testing - things I found I really needed. They are definitely "organic" and aren't yet part of a cohesive design. Any ideas for improvement are welcome.

Something I was thinking about just now. Not sure if these are actual improvements, but I wanted to throw them out there. This is on the aspect of the fact we're triggering these events manually during the launch sequence, but:

1. There seems to be little warning prior to the annunciation that we should cut out the outboard engines (to avoid over-thrusting). Would it be possible without adding too much to the code to give a sort of a 'projected outboard cutoff' annunciation some five to ten seconds (or .2 to .3 g's) prior to when the engines should be cut off? Either that, or have the event handling in stages (solid - "should think about pay attention to this annunciation" / blinking - "NEED to take action in response of this annunciation")?

2. External tank run-out and jettison. I know the annunciation is there that gives the fuel state of the tanks prior to empty. Could we start the runout countdown a little earlier in the staging without overburdening the user?

Again, these are thought points and not necessarily requests, but if they benefit this project in any way . . .

---------- Post added at 11:27 PM ---------- Previous post was at 06:22 PM ----------

Actually I think we can belay a lot of what I said in my previous post -- the annunciations are clear to work with, and I think a lot of where I was coming from was just unfamiliarity with the systems.

I do have something new to report though: I ran a practice RTLS abort with this spaceframe -- my experience had me running the ascent profile past outboard engine shutdown, then doing a pitchover to face retrograde. The external tanks separated as advertised and I had enough power to halt my prograde motion and build up a significant amount of return velocity by the time I had about 3-5% fuel left.

The above was done with a 40mt dummy payload. I'm going to try this maneuver again using glideslope but I think given some flight envelopes we already have some RTLS capability.

 

[kocmolyf]

I'm going to try this maneuver again using glideslope but I think given some flight envelopes we already have some RTLS capability.

Neat! I'm definitely interested to hear how this goes. You might force me to renege and actually implement aerodynamics in the tank separation.