Project The "Small Orbital Craft" Project

[Cobalt]

Based on discussion in this thread, I've decided to try to make this as my first project.

Keep in mind that this will probably evolve a lot over time.

A few factors I'm concerned with:

• Size: A lot to put in a very small space. Maybe increase size while keeping a one-seat configuration.
• Docking: Currently, no true docking port. If the size increases, maybe this could change.
• Parachutes: Location is an issue, depending on a docking port existing or not.

All said, I think this can be done. I would absolutely love input, advice, assistance (especially regarding textures) from anyone interested.

Suggestions for a name are welcome, too.

I've started the rough modeling, and once I feel like something's worth showing, I'll post shots.

 

[penlu]

Specify the problems with size? Not enough experiments, or not enough life support, or...

 

[Eagle]

For the docking port/parachute problem I can think of a few solutions. Assuming a capsule-like design.

1. Do a gemini style docking. You don't have a man-passable docking port, just grabbers, electrical and other cables and such. An EVA is required to enter the station.

2. Put the docking port on the side of the capsule (watch for aerodynamic problems). Keep the chute on top of the capsule.

3. Full Docking port on top. Store the chute somewhere else, but allow it to sling to the 'right place' when it deploys.

EDIT: I wouldn't really worry about the interior size. Mercury herself and even Gemini are much smaller than one would expect. Especially compared to Apollo. The only issue is the pilot may not be able to exit the craft without assistance.

 

[Zatnikitelman]

You could have the 'chute deploy from a side panel. The craft would come in at an odd angle depending on where the chute was, but instead of smacking the water with its flat-round heatshield, it could more easily slip into the water by presenting a more pointed profile.

 

[Andy44]

Gemini uses a chute that opens from above the cockpit, such that the crew sits upright during splashdown. There were plans for a version of Gemini that would use a parafol and wheels to make a runway landing, but it got shelved.

 

[eveningsky339]

Gemini uses a chute that opens from above the cockpit, such that the crew sits upright during splashdown. There were plans for a version of Gemini that would use a parafol and wheels to make a runway landing, but it got shelved.

I've always wanted someone to simulate that...

 

[Andy44]

I've got a photo of it around here somewhere that I took at the Udvar-Hazy museum, they've got the test article there, very cool.

 

[penlu]

Putting the parachute in the side IS NOT AN OPTION. The pilot already takes up too much space! A Gemini-style dock is also not an option, because the nose would have to either suddenly widen or we would have to move the docking port downwards to make it wider; it is JUST TOO NARROW. Remember that the top of the ship, when it starts rounding out, is a little less than half the ISS's docking port width. That is why my design calls for unfolding spars. The other options are a side dock (!?) or a parachute in the heat shield. Or just keep the chute in the nose.

EDIT: Space for the pilot really IS a problem. The pilot can barely get in and out, and is curled up into a ball while he's inside. An entire half of the spacecraft opens up to let him squeeze in.

 

[Cobalt]

Specify the problems with size? Not enough experiments, or not enough life support, or...

Well, for the most part, interior systems are probably going to have to be up to imagination. But now that you say that, I've got no clue where you'd place that. I need a sense of size, so let me re-study the drawings you did.

For the docking port/parachute problem I can think of a few solutions. Assuming a capsule-like design.
1. Do a gemini style docking. You don't have a man-passable docking port, just grabbers, electrical and other cables and such. An EVA is required to enter the station.
2. Put the docking port on the side of the capsule (watch for aerodynamic problems). Keep the chute on top of the capsule.

3. Full Docking port on top. Store the chute somewhere else, but allow it to sling to the 'right place' when it deploys.

EDIT: I wouldn't really worry about the interior size. Mercury herself and even Gemini are much smaller than one would expect. Especially compared to Apollo. The only issue is the pilot may not be able to exit the craft without assistance.

If we're assuming this is a modern craft, it might be arguable that there'd be a great deal more interior space than Gemini or Mercury, thanks to ever-shrinking computer systems. With a better electrical layout, perhaps a panel on a track of some sort could move to make room for a docking port. Maybe. Think something like sliding door with wiring done through what connects the panel to the track. The actual processors and what not wouldn't be in the moving panel, but inputs could. And they could cover another section of inputs. The panels would lock at each end of the track to keep them in place. If the whole thing is scaled up maybe two feet, and the shape changed just a touch, this could provide space for a full scale docking port. But then, the matter becomes how does the door open. I'd assume it'd have to be one like that found on the docking port of the XR5 addon.

You could have the 'chute deploy from a side panel. The craft would come in at an odd angle depending on where the chute was, but instead of smacking the water with its flat-round heatshield, it could more easily slip into the water by presenting a more pointed profile.

If the heat shield is providing some lift and it levels off a bit (if I'm blisteringly wrong about how this works feel free to correct me) the side 'chute would be a mighty jarring event.

Putting the parachute in the side IS NOT AN OPTION. The pilot already takes up too much space! A Gemini-style dock is also not an option, because the nose would have to either suddenly widen or we would have to move the docking port downwards to make it wider; it is JUST TOO NARROW. Remember that the top of the ship, when it starts rounding out, is a little less than half the ISS's docking port width. That is why my design calls for unfolding spars. The other options are a side dock (!?) or a parachute in the heat shield. Or just keep the chute in the nose.

EDIT: Space for the pilot really IS a problem. The pilot can barely get in and out, and is curled up into a ball while he's inside. An entire half of the spacecraft opens up to let him squeeze in.

If it's so small inside, though, it would seem getting out of or back in would take tremendous effort.

Something else I thought of: If the SM is what fires for reentry, what will move it out of the way of the capsule proper? If this goes through using spacecraft3 (Which is most likely) would there be a way to program post-jettison sequences? (We can cross that when we come to it.)

I had other ideas but they provided more problems than they solved so they're scrapped.

In any case, I'm working on the first stage now. I can scale up or down as necessary based on what happens.

 

[Dman1410]

Guys for the name of the ship i came up with these...

SparrowHawk
or
S.S SparrowHawk

i know there the same name but should there be a S.S before the name or should it just be called SparrowHawk?

 

[Cobalt]

Guys for the name of the ship i came up with these...

SparrowHawk
or
S.S SparrowHawk

i know there the same name but should there be a S.S before the name or should it just be called SparrowHawk?

SS makes me think naval ship. We should get a list of names and have a poll on the favorites when it's close to release.

 

[astrosammy]

And S.S. makes me think HUGE ship.

 

[Cobalt]

I need more input on something:

For the first stage, one engine or four smaller ones?

 

[Urwumpe]

I need more input on something:

For the first stage, one engine or four smaller ones?

How much thrust should the first stage have? If you know that, you can choose a fitting engine for the thrust range from the list on astronautix.com and use this as reference. I would calculate around 20% more thrust for selecting the engine as initially required - the capsule might grow quickly in mass.

 

[penlu]

I left out one important fact: the capsule is one meter tall. I made it the smallest that could possibly fit a pilot inside.

Getting in and out shouldn't be a problem though. An entire half of the ship opens up, as I said.

Ah yes. I hope I mentioned the rocket was solid-fueled.


-----Posted Added-----


And why the Sparrowhawk? Sparrows are small, but hawks are big. I just prefer small orbital craft. My first drawing called it an "orbital thingy." Lol.


-----Posted Added-----


Triple post:

If I only had a scanner around, I could show you my pencil drawings. I always found using the Paint program hard.


-----Posted Added-----


zomg quadruple post I keep leaving things out:

seriously Sparrowhawk is a bit much for such a small thing.

 

[Cobalt]

How much thrust should the first stage have? If you know that, you can choose a fitting engine for the thrust range from the list on astronautix.com and use this as reference. I would calculate around 20% more thrust for selecting the engine as initially required - the capsule might grow quickly in mass.

Well, lets see. The Redstone was 69.3 feet high and without the Mercury capsule it weighed 61,207 pounds (27,763 kg) at ignition, and was powered by the 75-110 A-7 that put out 78,000 pounds-force (350 kN) thrust at sea level for 121 seconds. If the original idea is a 20 foot rocket (making my calculations easier, I failed algebra a few times), that's roughly 3.5 times shorter, and if the weight follows suit, give or take, that'd be 17,487.1 lbs. So, if going on this alone, it'd need to make 22,285 pounds-force. If we just assume here. If my math is embarrassingly wrong, do correct.

Also, let's keep the names for the rocket itself. I kind of like the SOC being the official name of the capsule itself. It's pretty much what it is.

 

[eveningsky339]

Well, lets see. The Redstone was 69.3 feet high and without the Mercury capsule it weighed 61,207 pounds (27,763 kg) at ignition, and was powered by the 75-110 A-7 that put out 78,000 pounds-force (350 kN) thrust at sea level for 121 seconds. If the original idea is a 20 foot rocket (making my calculations easier, I failed algebra a few times), that's roughly 3.5 times shorter, and if the weight follows suit, give or take, that'd be 17,487.1 lbs. So, if going on this alone, it'd need to make 22,285 pounds-force. If we just assume here. If my math is embarrassingly wrong, do correct.

Also, let's keep the names for the rocket itself. I kind of like the SOC being the official name of the capsule itself. It's pretty much what it is.

The Mercury capsules were incredibly small. You may need some sort of solid-motor strap-ons to give the rocket enough velocity to reach orbit. Unless you manage to make a fairly light capsule, of course.

 

[Eagle]

The other alternative to cutting mass is to make the launcher wider. Increasing the volume available for fuel at the rate of r^2 while the dry mass of the rocket increases closer to linearly (would be linear if the rocket had no cap on top).

You shouldn't have too much of the eggshell problem because of the relatively small size of the launch vehicle.

 

[Zatnikitelman]

Are you still trying for a solid rocket 1st stage? If you are, why not use a variant of the Graphite Epoxy Motors (GEMs)? They seem to be the smallest solid motors that exist that have the power to even lift the vehicle given the 22k foot pound number you gave. Unfortunately, they burn out after 60-90 seconds. I don't think you'll find a launcher in the 20 foot range that gives you the thrust you need.

If you do decide to go the liquid fueled route, look at the RS-27A used on the Delta II, or even the RL-10 designed for high atmosphere-vacuum conditions, but could be used on the ground.

 

[penlu]

The Mercury capsule was 3.51 meters tall and 1.89 meters wide.

The SOC is 1 meter tall and 0.95 meters wide. With the service module, it's another 0.65 meters on the height.

Weight will not be a problem.


-----Posted Added-----


And I meant that the ENTIRE rocket is solid-fueled. Unless that's not feasible? I think that solid is simpler and cheaper.