Designing our own Spacecraft

[NSEP]

Ok, first off, i know and understand that space is very hard, and that my design probably is too amateur to make it into orbit, but i do this for fun and as a hobby/learning project. Im not a rocket scientist, just a curious person who likes to calculate stuff and learn things along the way. Oh, and if you want to contribute, feel free ask for contributing if you want to join along! 

THIS IS A WORK IN PROGRESS THREAD!

General Idea

My plan is to design a spacecraft capable of launching and safely returning back to Earth from orbit. And after thats done, we design a spacecraft capable of manned spaceflight and docking with stations.

Limits

Our Spacecraft is not going to be heavier than 10 tons or lighter than 6 tons. We don't have a launch vehicle yet, im thinking of using Atlas V. The spacecraft can be no wider than 3 meters and no longer than 10 metres. 

Untitled Space Craft 1needs a name help

This spacecraft is going to be the testing bed for several important things of orbital spaceflight and (mostly) re-enty. It will have a ball shaped capsule, The diameter is about 2 metres, probably a bit bigger. This is not a manned spacecraft, but instead is designed to send science experiments to orbit and to be returned, mainly biological samples. It may serve as a mini and unmanned ISS.

Important components and parts:

 

Capsule

- The Skeleton is going to be made out of steel bars. The steel bars are cylinders and have a diameter of 2,5cm. 1m of this steel bar masses in at 3779.669grams or 3.78kg. Now lets make a steel ring shall we? We first need to know the circumference of the ring we need, we know the radius of the capsule is one metre so 2*pi*1=6.3 metres. Now 6.3 metres times the mass per meter (3.78kg) and we have the the mass per ring, so 6.3*3.78=23.814kg. Now that we have the mass per ring, we can continue to make the skeleton. Our sphere needs, lets say, 5 rings, (4 rings longitude and 1 ring latitude).Thats 23.814*5=119.07kg. for our skeleton in total.

- The Skin (NOT HEATSHIELD) of the the capsule is going to be made out of steel, 10mmthick. Considering the ISS only has 6,25mm of protection from the vacuum of space. We might use Carbon Fibre instead, wich is light and durable, but expensive.

- The Heatshield is made out of 150mm of Oak Wood. Yes, wood, the Chinese used 5.9 inches of Oak wood to test their re-entry vehicle. 

- The Parachute is behind the heatshield, and deploys during the last moments of re-entry. Im not an aerodynamics expert so i might need some help with that

- Resources like power are transfered via a special hatch that would be plugged to the Service Module. The plugs would be unplugged and the hatch would be closed during re-entry, a drawing explaining it all might come in the future. Such a mechanism might also be used to protect the window.

- Avionics and most Electronics are out of my field. If anyone here knows anything about that and wants to help, feel free to join in.

-Oh yeah, the inside would be pressurized and the outside would be protected with a thermal blanket.

Propulsion/Service Compartment.

- Fuel tanks are made of steel, oh and they would carry Hydrazine Nitrogen for RCS.

- Im not a rocket engine person, so i would have to find a pre-designed Hydrazine Nitrogen RCS thruster. If anyone is willing to build their own thruster for the spacecraft, feel free to join in

- The Solar Panels are also on the thing, size depends on the required power of the spacecraft. The SC (Service Compartment) would also contain additional batteries.

- Communication is also out of my field. Again, if you want to help with that, feel free to contribute.

- It would need to have a special arm for the Resource Transfer Plug and straps to attach to the capsule.

- Oh and dont forget the steel bars to keep things together. I can't think of any more things a SC would need right now. Any ideas?

 

 

 

Edited January 1, 2018 by NSEP

[RoadRunnerAerospace]

welp, let see

I recommend  using c/f as the main body shell for the capsule, very thin steel should do (maybe 4 tons full?).  I recommend not using hydrazene,  saying that its awfully hard to come by, and pretty skin meltingly-dangerous.  Im working on a gasoline/gox engine design right now, fuller details soon.

 

Oh, and expansion will be a problem with the steel bars

 

https://imgur.com/iIRnBiF

 

 

Edited January 1, 2018 by RoadRunnerAerospace

[NSEP]

6 hours ago, RoadRunnerAerospace said:

welp, let see

I recommend  using c/f as the main body shell for the capsule, very thin steel should do (maybe 4 tons full?).  I recommend not using hydrazene,  saying that its awfully hard to come by, and pretty skin meltingly-dangerous.  Im working on a gasoline/gox engine design right now, fuller details soon.

Hmmm, Carbon Fibre is pretty expensive (€20 to €100 per KG) but does not have any expansion problems right? I think i will have to calculate the weight and cost of such a body shell first.

Hmmmmm, well i don't know about using Bipropellant thats not hypergolic. Mainly because its used for RCS too. I think Hydrogen Peroxide is better choice, not really hard to find, non toxic, non explosive snd non flammable. Im still interested in your Gasoline and Gaseous Oxygen engine though, maybe for the Re-entry motors.

7 hours ago, RoadRunnerAerospace said:

Oh, and expansion will be a problem with the steel bars

Is there any way to prevent heat expansion. Or is there any material that is non-flammable, that is cheap and basic to handle? Wait, is the main skeleton even necessary?

[Piatzin]

4 hours ago, NSEP said:

Is there any way to prevent heat expansion. Or is there any material that is non-flammable, that is cheap and basic to handle? Wait, is the main skeleton even necessary?

I have no idea how to do this sort of thing - you guys are practically rocket scientists when compared to me lol - but I'd like to learn. It's interesting

Some thoughts that might not actually make sense:

The skeleton, IMO, would be quite crucial, otherwise the thing will end up being damaged during reentry, and might get partially crushed/imploded. So there should be something to reinforce the capsule. Theoretically, if the whole thing is made of the same material, the expansion rate will be near-identical, so there is no risk of cracking, etc. The problem is the skin will be exposed to a lot of heat, whereas the insides, being inside, will be exposed to less heat, and so will expand less than the outsides. Right? Not all parts will be exposed to the same level of heat, so there will be uneven expansion. The solution would be to get a material that expands less, and put that on the outside (and make the insides out of something slightly more susceptible to expanding) or make everything out of a material that does not expand at all. Which is......difficult.

.....

Am I making sense?

EDIT: I can help with the parachute part, if needed

Edited January 1, 2018 by Earthlinger

[kerbiloid]

Imho, you would start with the ship objectives which would define the number of crew.
Then proceed with the crew seats layout and airlocks. All of them have sizes which are not arbitrary.
This will define the capsule sizes.
Do not forget to take into account D/H ratio, comparing to the irl capsules.

[Piatzin]

@NSEP

Do you mind if I do some calculations for the parachute(s)?

[Kerbinchaser]

*Gulp*

 

Good luck. 

[NSEP]

41 minutes ago, Earthlinger said:

@NSEP

Do you mind if I do some calculations for the parachute(s)?

Yeah sure! That would be very much appreciated!

 

1 hour ago, kerbiloid said:

Imho, you would start with the ship objectives which would define the number of crew.
Then proceed with the crew seats layout and airlocks. All of them have sizes which are not arbitrary.
This will define the capsule sizes.
Do not forget to take into account D/H ratio, comparing to the irl capsules.

Thanks, i will keep that in mind!

[RoadRunnerAerospace]

5 hours ago, NSEP said:

Hmmm, Carbon Fibre is pretty expensive (€20 to €100 per KG) but does not have any expansion problems right? I think i will have to calculate the weight and cost of such a body shell first.

Hmmmmm, well i don't know about using Bipropellant thats not hypergolic. Mainly because its used for RCS too. I think Hydrogen Peroxide is better choice, not really hard to find, non toxic, non explosive snd non flammable. Im still interested in your Gasoline and Gaseous Oxygen engine though, maybe for the Re-entry motors.

Is there any way to prevent heat expansion. Or is there any material that is non-flammable, that is cheap and basic to handle? Wait, is the main skeleton even necessary?

Carbon fiber is very light, durable, somewhat heat resistant (depending on type), and easy to build with, Im not sure about the expansion problems though, Ill have to look into it. Were not talking about normal home peroxide here, this is 90% peroxide, the stuff that you have is at a upper level of 20%, it can cause chemical burns. 

[NSEP]

1 hour ago, Earthlinger said:

Some thoughts that might not actually make sense:

The skeleton, IMO, would be quite crucial, otherwise the thing will end up being damaged during reentry, and might get partially crushed/imploded. So there should be something to reinforce the capsule. Theoretically, if the whole thing is made of the same material, the expansion rate will be near-identical, so there is no risk of cracking, etc. The problem is the skin will be exposed to a lot of heat, whereas the insides, being inside, will be exposed to less heat, and so will expand less than the outsides. Right? Not all parts will be exposed to the same level of heat, so there will be uneven expansion. The solution would be to get a material that expands less, and put that on the outside (and make the insides out of something slightly more susceptible to expanding) or make everything out of a material that does not expand at all. Which is......difficult.

.....

Am I making sense?

I think it makes sense, different materials have different expansion rates.

What if we made a special mesh like structure to prevent the heatshield from cracking and breaking, instead of just one whole piece. If we had the heatshield in seperate parts every part would expand on its own and would not expand with the rest of the heatshield, preventing stress and damage. I don't know if this also makes sense.

Are there any materials that do not expand, and are sturdy and solid but are not too expensive?

[RoadRunnerAerospace]

1 minute ago, NSEP said:

I think it makes sense, different materials have different expansion rates.

What if we made a special mesh like structure to prevent the heatshield from cracking and breaking, instead of just one whole piece. If we had the heatshield in seperate parts every part would expand on its own and would not expand with the rest of the heatshield, preventing stress and damage. I don't know if this also makes sense.

Are there any materials that do not expand, and are sturdy and solid but are not too expensive?

If you break the heatshield into parts, it greatly increases the risk of "crunch n burn"

[Piatzin]

(Sorry for the late reply I was walking my dog )

Two questions for the parachute:

First, what's the mass of the descent stage? You said 10 tons max for the whole rocket, so I'm guessing roughly 500-1000kg, depending on the efficiency of the rocket itself.

Second, how fast do you want the rocket to be moving when the parachutes are deployed? (Ideally 4-5 m/s, as we all know from KSP :P)

Edited January 1, 2018 by Earthlinger

[Matuchkin]

Am I correct when I say that by far, the most important concern of spacecraft design is structural integrity?

[Piatzin]

4 minutes ago, Matuchkin said:

Am I correct when I say that by far, the most important concern of spacecraft design is structural integrity?

Yes.

We don't want it going kablooie, BUT, I hear that triangles are sturdy...

Honestly though, for an orbital class rocket (or at least, something that actually enters space per se), we're kidding ourselves if we think we can build something fool-proof and risk-free.

Edited January 1, 2018 by Earthlinger

[NSEP]

9 minutes ago, RoadRunnerAerospace said:

If you break the heatshield into parts, it greatly increases the risk of "crunch n burn"

Sorry, i meant to say tiles, but if its in one piece and something hit it, it would crack right? Like how you can smash a brick in half with one hit but can't do that with a house?

 

7 minutes ago, Earthlinger said:

(Sorry for the late reply I was walking my dog )

Two questions for the parachute:

First, what's the mass of the descent stage? You said 10 tons max for the whole rocket, so I'm guessing roughly 500kg, depending on the efficiency of the rocket itself.

Second, how fast do you want the rocket to be moving when the parachutes are deployed? (Ideally 4-5 m/s, as we all know from KSP :P)

The maximum mass of the spacecraft (not including rocket/launch vehicle) is 10t, so lets just say the descent stage is 3t for now, i have yet to calculate the actual mass of the spacecraft...

[Matuchkin]

4 minutes ago, Earthlinger said:

Honestly though, for an orbital class rocket (or at least, something that actually enters space per se), we're kidding ourselves if we think we can build something fool-proof and risk-free.

Oh, that- yeah, that. I think we're doing a bit more than kidding ourselves here.

[NSEP]

27 minutes ago, RoadRunnerAerospace said:

Were not talking about normal home peroxide here, this is 90% peroxide, the stuff that you have is at a upper level of 20%, it can cause chemical burns. 

Well, then i think the only plausibe option is to use liquid nitrogen thrusters for RCS and your Gasoline engine for the de-orbit burn. Thanks.

[RoadRunnerAerospace]

5 minutes ago, NSEP said:

Well, then i think the only plausibe option is to use liquid nitrogen thrusters for RCS and your Gasoline engine for the de-orbit burn. Thanks.

Well, I was doing gasoline for the initial tests, any fuel should work (thats not insane)

[NSEP]

2 minutes ago, RoadRunnerAerospace said:

Well, I was doing gasoline for the initial tests, any fuel should work (thats not insane)

Good! I think Gasoline is okay, not too expensive, neither do we need a high ISP/Delta-V

[Piatzin]

So the parachutes would be kinda big.....

Written work:

To slow a 3 tonne craft to a speed of 5 m/s at sea level, we would need a parachute with an area of 2562 m2. That's a diameter of roughly 57-58 meters (5709 cm to be exact)

Which is very big. And these calculations are at sea level, which is where there is the most drag. At higher altitudes, less air equals less 'efficiency' per square meter of parachute. Therefore, a chute 58 meters in diameter would not actually slow a 3 tonne carft to 5 m/s when deployed at a higher altitude. To actually do that, it'd have to be larger, so, say, maybe 65 or even 70 meters in diameter.

Maybe we could do the landing SpaceX style?

[RoadRunnerAerospace]

Just now, Earthlinger said:

 

Maybe we could do the landing SpaceX style?

soyuz.

[Ultimate Steve]

5 minutes ago, Earthlinger said:

So the parachutes would be kinda big.....

Written work:

To slow a 3 tonne craft to a speed of 5 m/s at sea level, we would need a parachute with an area of 2562 m2. That's a diameter of roughly 57-58 meters (5709 cm to be exact)

Which is very big. And these calculations are at sea level, which is where there is the most drag. At higher altitudes, less air equals less 'efficiency' per square meter of parachute. Therefore, a chute 58 meters in diameter would not actually slow a 3 tonne carft to 5 m/s when deployed at a higher altitude. To actually do that, it'd have to be larger, so, say, maybe 65 or even 70 meters in diameter.

Maybe we could do the landing SpaceX style?

Or Soyuz style. You'd need way smaller chutes to do it that way.

EDIT: Apollo splashed down at 10m/s.

Edited January 1, 2018 by Ultimate Steve

[NSEP]

Yes, maybe Soyuz style, with a smaller chute and a 10m/s descent speed, and explosive engines to slow it down.

[Piatzin]

4 minutes ago, Ultimate Steve said:

Or Soyuz style. You'd need way smaller chutes to do it that way.

Soyuz's main chute was a thousand square meters. That's still pretty big. Also, how do we guarantee the parachute isn't ripped off? I'm not familiar with materials/framework for attaching chutes

[NSEP]

3 minutes ago, Earthlinger said:

Soyuz's main chute was a thousand square meters. That's still pretty big. Also, how do we guarantee the parachute isn't ripped off? I'm not familiar with materials/framework for attaching chutes

Well, we aren't trying to make the parachute light and small, so a thousand square meters does not seem like a problem.

I might come up with a parachute holding rope gizmo thing, so it at least does not rip apart from the capsule.