Spaceplane design advice

[Jonfliesgoats]

That's not a soviet shuttle.  it's the concept art for the X-20 Dyna-Soar.  The Soviet version as the Spyral program.

The Soviet shuttle looked like ours minus the main engines since they had better boosters.

Edited October 26, 2016 by Jonfliesgoats

[Jonfliesgoats]

With regard to spaceplane design, even the over simplified aerodynamics in stock KSP do a nice job of introducing players to the rudimentary challenges of design and testing of aircraft.  After wiping out your craft on the runway to a point where it gets boring, you find yourself investing the time to make sure your wing loading is low enough to get airborne before you overstres your gear, your main landing gear is not too far aft of the CG so you can rotate, and your fuel systems don't burn your CG into an uncontrollable region as you fly.

Fun!

With spacecraft you can even calculate the altitudes for maximum dynamic pressure and acceleration of reentering spacecraft an given trajectories!  They're actually not that far off! When you look at the challenges American engineers faced in designing accurate reentry vehicles of their ICBMs, you see that they faced some real hurdles.  You know why we don't have ultra-pointy MIRVs?  Pointy parts near the stagnation point get super hot and melt, but sacrificing a little drag and shockwave for some roundness make the craft much more tolerant of thermal stress!  Guys figured this stuff out with slide rules, coffee and bad jokes!  That engineering feat along with laser gyros, atomic clocks, advances in computing and more coffee, cigarettes and bad jokes meant US nukes could be lower yield weapons while the soviets relied on megaton-scale warheads because their reentry vehicles weren't as accurate.  But I digress.

I can rant on and on about how we get compressibility and viscosity wrong in KSP, when it comes to planes.  Considering we have a game rather than a supercomputer with access to wind tunnels and a production facility o build mock-ups and prototypes, we still get a pretty decent taste of he challenges of flight.

 

[Jonfliesgoats]

Planes do make lousy rockets, as someone said.  I don't even use them for crew transports or tankers to LKO anymore and prefer reuseable rockets.  By the time you factor the general complications of getting your spaceplane to LKO and reliability, it's a wash between reuseable rockets and spaceplanes.

I do use spaceplanes for other things, though.  If I need to get observations on the far side of Kerbin, it is easier to fly a spaceplane there at 850m/s or pop Ito a brief, suborbital flight rather than launch to orbit, reenter, etc.

Edited October 27, 2016 by Jonfliesgoats

[Jonfliesgoats]

1 hour ago, eagle92lightning said:

man shut up. I am going to work at NASA so please I respect cosmonauts but right now I have no respect for you. And do you even know what EM-2's objective even is?

Let's cut each other some slack.  We have all been proud to be assigned to a shiny new program on the forefront of NNN.  We have all thought that, by being admitted into the ranks of test pilots, flight test engineers, etc, that we have made some cut and are somehow part of an elite group.  It's worse when we tell our employees or peers this.  Our egos are tempted to run away with these thoughts.  I have been a much bigger jerk than this guy in real life and learned that, despite my titles and awards, I wasn't as sharp as the guy next to me.  I have been the guy making off color jokes that I thought were really hilarious while very kind people tolerated my attempts at humor.  So we all meet up at different phases in our human and professional experience and that sometimes gets us to see each other when we are not at our best.  As nasty as any of us may seem, I have been nastier.  People forgave me.  Please forgive this guy.

None of us are that important, really.  That's the beautiful human story of flight, when you think about it.  The combined efforts of egotists, jerks, maniacs, war criminals, profiteers and fools somehow got a surface-bound group of primates into the air and onto another celestial body.  It's not that we stand on the shoulders of giants.  We stand on the shoulders of very faulty humans and we still fly!  Space flight is something that is bigger and better than any of us as individuals.

Ideas from people we assume are uninformed evolve into great products.  Imagine telling a young Goddard or Korolev to shut up when they are simply excited to talk about flying and space.  You'd shut down a great mind and turn into one of the many unknown pigs of history!  In truth we hear about all these great innovators who rose despite the forces acting against them.  Imagine how much more knowledge and capability we would have if those forces were weaker.  How many great innovations have been suppressed because some body listened when a person in a position of perceived expertise told them to shut up?

Its rare to find a community of people excited about flight, exploration, science, etc..  Its rare to find a community of people who will research what they don't know on their own and find solutions to engineering and operational challenges, even if those challenges are simulated.  Let's not dial these guys back by silencing them.  We need all these people and all this excitement.

If you believe in your program and product, you know it can weather a little criticism on the internet.

[eagle92lightning]

20 minutes ago, Jonfliesgoats said:

Let's cut each other some slack.  We have all been proud to be assigned to a shiny new program on the forefront of NNN.  We have all thought that, by being admitted into the ranks of test pilots, flight test engineers, etc, that we have made some cut and are somehow part of an elite group.  It's worse when we tell our employees or peers this.  Our egos are tempted to run away with these thoughts.  I have been a much bigger jerk than this guy in real life and learned that, despite my titles and awards, I wasn't as sharp as the guy next to me.  I have been the guy making off color jokes that I thought were really hilarious while very kind people tolerated my attempts at humor.  So we all meet up at different phases in our human and professional experience and that sometimes gets us to see each other when we are not at our best.  As nasty as any of us may seem, I have been nastier.  People forgave me.  Please forgive this guy.

None of us are that important, really.  That's the beautiful human story of flight, when you think about it.  The combined efforts of egotists, jerks, maniacs, war criminals, profiteers and fools somehow got a surface-bound group of primates into the air and onto another celestial body.  It's not that we stand on the shoulders of giants.  We stand on the shoulders of very faulty humans and we still fly!  Space flight is something that is bigger and better than any of us as individuals.

Ideas from people we assume are uninformed evolve into great products.  Imagine telling a young Goddard or Korolev to shut up when they are simply excited to talk about flying and space.  You'd shut down a great mind and turn into one of the many unknown pigs of history!  In truth we hear about all these great innovators who rose despite the forces acting against them.  Imagine how much more knowledge and capability we would have if those forces were weaker.  How many great innovations have been suppressed because some body listened when a person in a position of perceived expertise told them to shut up?

Its rare to find a community of people excited about flight, exploration, science, etc..  Its rare to find a community of people who will research what they don't know on their own and find solutions to engineering and operational challenges, even if those challenges are simulated.  Let's not dial these guys back by silencing them.  We need all these people and all this excitement.

If you believe in your program and product, you know it can weather a little criticism on the internet.

I completely agree!

[niic]

Good ssto's can go any where I am ok at them but go to matt lowne youtube for a lot of help

[eagle92lightning]

just landed my first plane!

[eagle92lightning]

I tried the panther afterburning turbofans today I like them thoughts?

[niic]

1 hour ago, eagle92lightning said:

I tried the panther afterburning turbofans today I like them thoughts?

 I like them very fast i managed to get them to 822 m/s just remember to switch mode for more speed

[Jarin]

2 hours ago, niic said:

 I like them very fast i managed to get them to 822 m/s just remember to switch mode for more speed

Interestingly, they go faster lower, since the thrust you gain overwhelms the thicker air drag (assuming your plane isn't a brick). A sleek panther-powered plane can skim the waves at over 900m/s.

[AeroGav]

My advice for any newbie is not to try and start with a shuttle ("plane on a rocket") design. They are very hard to build and fly in KSP, with few advantages.   Gravity turn savescum spam,  wings messing with rocket stability,  centre of mass shifting around as fuel burns off and boosters decouple, the joys of off-axis thrust.

A true SSTO spaceplane is hard and requires top-level tech, so if you want a gentler introduction, I suggest an engine-shedding design -

• build a high-wing monoplane with the rocket engine at the rear of the fuselage (terrier or NERV).   60kn of rocket thrust for every 15 tons weight.
• mount your jet engines in pods under the wings on decouplers.   Jettison them when they flame out - this greatly reduces the dry mass of the craft and makes it much easier to reach orbit - and beyond.  Jet engines are heavy.
• adjust the height of the wing to make sure the thrust output of the jet engines is neither above nor below your  centre of mass, that way pitch doesn't change as you throttle up and down.   Slide the engine pods backwards and forwards on the pylons until they are centred over the plane's centre of gravity. so that the plane's centre of gravity does not move when the engines are decoupled. 
• whiplash are probably the best engine for this.  They are nearly as good as rapier but much cheaper, only slightly more than panther cost.
• empty all the rocket fuel tanks and check the centre of gravity.  hopefully your cockpit and passenger cabins balance the weight of the rocket engine at the back, and give you a centre of mass in the right place vs centre of lift
• add fuel tanks back, putting some at the front and some at the rear, so that centre of mass does not change as fuel burns off.
• profit.

An engine dropping spaceplane is still cheaper to launch than a shuttle, easier to fly and more capable.

This is an ultra low tech spaceplane.  First jet engine available.  Fixed landing gear. Not really economic but fun.  The video was done in old version of KSP, in the current release you won't have to worry about locking fuel tanks for centre of gravity, and heating is less severe.

A single Whiplash/NERV design can go a little further than low orbit, actually.  Sorry no sound !

My attempt at a space shuttle.   

Air launch to orbit - would be the best approach of all, unfortunately KSP deletes the carrier plane once it gets 2.5km from the orbiter, so no re-use :-(

[stardog573]

Helpful post. Check it out.

[eagle92lightning]

10 hours ago, niic said:

 I like them very fast i managed to get them to 822 m/s just remember to switch mode for more speed

I magares about 1000m/s in a not very steep dive.

[AeroGav]

31 minutes ago, eagle92lightning said:

I magares about 1000m/s in a not very steep dive.

Panther are OK in career mode when you don't yet have better engines.   

But, you can get up to 1300m/s at 22km or more, in level flight, with one engine per 20tons launch weight, on RAPIERs.   This means you need only another 900 m/s to get to orbit.

Look at how fast I'm going on the "Whippynerv" video, before swapping to nuke power.

[eagle92lightning]

1 hour ago, AeroGav said:

Panther are OK in career mode when you don't yet have better engines.   

But, you can get up to 1300m/s at 22km or more, in level flight, with one engine per 20tons launch weight, on RAPIERs.   This means you need only another 900 m/s to get to orbit.

Look at how fast I'm going on the "Whippynerv" video, before swapping to nuke power.

yeah but I don't want to burn up on my way to space.

[AeroGav]

15 minutes ago, eagle92lightning said:

yeah but I don't want to burn up on my way to space.

1300 m/s is a pretty moderate speed.    Some folks post screenshots of 1600,  I think they're mad.

The higher up you are, the faster you can go without roasting because the air is thinner.   So above 20km 1300 is ok.   Above 1600 things can get pretty warm if you're not at 30km altitude or more.

Also, it helps if you use an inline cockpit.    The further back something is from the front of the plane, the less heat it gets.   Also, put the basic Communotron 16 antenna on the tip of your nose cone , that extends the shock wave further forward protecting the rest of your plane.

How fast should you go?  1150 is mach 3.8, the speed at which Rapier produce max power in airbreathing mode.   You want at least this, or you're not getting the most out of them.    900 is mach 3, peak for Whiplash.

At mach 4.5 , the Rapier is still producing 80% of it's peak power, so the loss is gradual if you go a little bit too fast.  After mach 4.5 the curve takes a sharp turn downward however, by mach 6 thrust will have fallen to zero.     If you can get that fast airbreathing, you probably brought too many jet engines (extra weight to carry to orbit), have too little wing and too much thermal protection.  

[eagle92lightning]

15 minutes ago, AeroGav said:

1300 m/s is a pretty moderate speed.    Some folks post screenshots of 1600,  I think they're mad.

The higher up you are, the faster you can go without roasting because the air is thinner.   So above 20km 1300 is ok.   Above 1600 things can get pretty warm if you're not at 30km altitude or more.

Also, it helps if you use an inline cockpit.    The further back something is from the front of the plane, the less heat it gets.   Also, put the basic Communotron 16 antenna on the tip of your nose cone , that extends the shock wave further forward protecting the rest of your plane.

How fast should you go?  1150 is mach 3.8, the speed at which Rapier produce max power in airbreathing mode.   You want at least this, or you're not getting the most out of them.    900 is mach 3, peak for Whiplash.

At mach 4.5 , the Rapier is still producing 80% of it's peak power, so the loss is gradual if you go a little bit too fast.  After mach 4.5 the curve takes a sharp turn downward however, by mach 6 thrust will have fallen to zero.     If you can get that fast airbreathing, you probably brought too many jet engines (extra weight to carry to orbit), have too little wing and too much thermal protection.  

thanks I am really working on spaceplanes right now

[eagle92lightning]

I retired my first spaceplane (it never made it to orbit ) named the goliath for reasons that will be obvious as soon as I can figure out how upload pictures to the forums that are on my phone.

[Bdyer]

42 minutes ago, eagle92lightning said:

I retired my first spaceplane (it never made it to orbit ) named the goliath for reasons that will be obvious as soon as I can figure out how upload pictures to the forums that are on my phone.

https://imgur.com/a/6qNgm

Thats my "goliath" over 2000 tons on the runway

[eagle92lightning]

20 minutes ago, Bdyer said:

https://imgur.com/a/6qNgm

Thats my "goliath" over 2000 tons on the runway

yours wins compared to that thing mines a whimp!

[rocketbuilder]

On 27 October 2016 at 0:06 AM, eagle92lightning said:

man shut up. I am going to work at NASA so please I respect cosmonauts but right now I have no respect for you. And do you even know what EM-2's objective even is?

Tbh I like NASA, but the fact the Russia (soviet created) have the only manned space craft as of yet is a bit disappointing. Anyway I shouldn't be off topic...

[Bdyer]

Here is my latest creation, It has 6K dv once it gets to orbit and I think I can make it to duna with it.  I just need to test and add some extra Vtol capability

http://imgur.com/a/h5dd4

 

 

Edited November 1, 2016 by Bdyer

[eagle92lightning]

12 hours ago, rocketbuilder said:

Tbh I like NASA, but the fact the Russia (soviet created) have the only manned space craft as of yet is a bit disappointing. Anyway I shouldn't be off topic...

USA USA USA USA! Actually I meant to type... NASA NASA NASA NASA NASA NASA NASA!!!!!!!!

[eagle92lightning]

I have built my first spaceplane (pretty sure it will work but can't take off from it(not long enough. MAKE IT LONGER Squad!)) The X-376 Valkerie 

[Combatsmithen]

EAGLE YOU NECROED YOUR OWN THREAD!

 

Also what you see in my picture is the Kerbin shuttle. Capable of carrying a medium payload to LKO, taking off from the runway and landing back at the runway.

Edited February 14, 2017 by Combatsmithen