Staged Airbreather Workshop

[AeroGav]

Does anyone else spend so much time making aircraft,  that they never got good at huge rockets, moar boosters and in-orbit assembly?  So that when you feel an urge to view the outer reaches of the Kerbol system,   the easiest way is to make a plane that leaves bits of itself behind en-route.  (Intentionally)

https://onedrive.live.com/redir?resid=7003A8806D8A6B2C!727&authkey=!ALzHMCmQJPIc63Q&ithint=file%2ccraft

This one's already lost a stage - the landing gear that it took off on, wasn't fast enough to F12 sorry.

It'll be raining Rapiers, three of them at any rate.

As we pass mach 6, we shed the outboard NERVs.

Above 50km, there's no need for the extra control surfaces.

Nor those empty wings.  It leaves us an aft CG but since there's no real atmosphere we get away with it.   

In orbit.  This stage has about 650 fuel left in it, enough to get us to Laythe I reckon - 5000dV?

I couldn't be bothered to fly to Laythe today,  but I did verify that the Laythe airbreathing stage works on Kerbin - it's actually kinda sporty.  Unfortunately the rest of the plane fell onto and wrecked the space centre.

After launching the cruise missile separating the airbreathing stage, the return stage  was also given a quick once over.   The landing gear of the Laythe stage have already gone by this point.

It could probably use some more optimisation but it's a start, at any rate.

For career mode games, something a little more prosaic -

Spoiler

 

Let me go you F*-*-*R!

Freedom

 

Or we could just build an utter monstrosity

Spoiler

 

...and bomb the runway with our landing gear...

Occasionally, it does actually reach orbit

...in faraway places..

 

 

It's easier than you'd think, once you get your head around it.    

The trick is to stay symmetrical in two axes (lateral, vertical) unless you're a true genius.   Tacking on stages to the back of your airplane is fine, just remember to add a wing section to each engine part so that the lift offsets the weight and shedding this item has no effect on your CG.

And if your new stage needs more engines, use bicouplers.  Don't underslung pods, because you won't be able to keep the nose down when the air gets thin.   Those planes I linked, look asymmetric , are asymmetric, but don't act asymmetric because they got wings on them heavy bits.    You underslung your motors you get off the boat.   Never go full asymmetric.

Edited April 14, 2016 by AeroGav

[AeroGav]

After the previous monstrosity, I resolved to put together a nice simple design that would be easy to replicate, would not abuse clipping, not require the presence of mods, be easy to fly and not succumb to over-engineering.

Well,  the over-engineering part was a struggle I tell you.   The part count crept upwards like the JSF budget.

So,  I present, the Frost Wing

https://onedrive.live.com/redir?resid=7003A8806D8A6B2C!729&authkey=!APewUzZ3WMhJHrM&ithint=file%2ccraft

 

The initial idea was a simple 1 nuke/1 rapier mk 1 plane that stages off it's rapier to solve engine placement / thrust axis issues simply.   But it had enough delta V that simply orbiting Kerbin felt like a waste.   Also, what to put between the cockpit and the NERV?  Mounting it directly overheats the cockpit.

Answer - ISRU !  Let's go to Duna and Back !    Only now it climbs sluggishly in the lower atmosphere and wastes half its fuel before going supersonic.  Pod mounted Panthers to the rescue.

Worse, I'd decided to revisit something that doesn't really work properly in KSP - landing flaps.  That took so much tuning.

Spoiler

 

In the real world, flaps and slats increase the amount of lift and drag produced by the wing they are attached to.   In KSP, the wing itself is unaffected, but the flap hinges downwards and itself generates more lift due to having a greater angle of attack.   Problems with this

1. you don't get much benefit because only the flap itself is making extra lift, a  small fraction of total wing area.

2. this extra lift is a because the flap is at higher angle of attack than the rest of the wing. If the aircraft as a whole is at high angle of attack, this wing flap can end up stalling out and you actually have less lift.   However most of the time we touch down at 5 to 10 degrees AoA as most landing gear configurations will not allow more due to tail strikes.

3. this extra lift is at the back of the wing and therefore produces a powerful pitch down force.  If you have a docile, stall resistant design it can be very hard keeping the nose up when flaps are deployed.

Eventually I ended up fitting double canards to the nose and having them deflect when flaps are deployed.  In addition, the cockpit's reaction wheels toggle on with the flap key as does an RCS thruster to try and push the nose up.    This was one of several changes that cost the aesthetic of the original design.

The flaps are useable on Duna provided you deploy them during the landing flare.   On Kerbin,  and at speeds much over 100 m/s, the RCS is not strong enough to overcome the pitch down effect from the flaps.  Due to the cockpit's limited monopropellant storage it is also wise to delay deployment until the last 100m or so.

I may revisit flaps on a terrestrial STOL plane,  i will try putting them on the leading and trailing edges of the wing so the pitch effects should cancel out.

 

Staging Info

First Space bar starts the Panthers

Second Space bar starts the Rapier

Third Space bar drops the Panthers

Fourth drops the Rapier and starts the NERV

 

Action Groups

RCS - not only starts the RCS, it enables capsule torque and deploys the landing flaps.   This is an experimental feature that may slightly reduce landing speeds.    Should only be used on Duna below 100 m/s , or the aerodynamic forces will overwhelm the RCS which is needed to overcome the pitch down effect of landing flaps.  Also should only deployed @ 100m above ground level or the RCS could run out.

Abort - toggles the panthers between afterburner and dry thrust.

Recommend flying to at least 10000m before attempting to go supersonic.  Use afterburner when levelling off to accelerate through sound barrier, cancel burner above 400 m/s.   Above 15km , turn A/B back on again, unless already over 750 m/s in which case press space bar to drop the pod mounted engines.   Above mach 2.8 drop these engines.

Bring an engineer for better mining.  There is a probe core in service bay so you won't need a pilot.

[Sharkman Briton]

I like this! I'm a bit lost on the career mode plane though, why use docking ports to separate? (apart from reusing the tanks, which you probably won't do because you need the fuel to get to orbit) And whats the point of the LF only tanks? Otherwise, all your craft look very Kerbal.

[AeroGav]

2 minutes ago, Sharkman Briton said:

I like this! I'm a bit lost on the career mode plane though, why use docking ports to separate? (apart from reusing the tanks, which you probably won't do because you need the fuel to get to orbit) And whats the point of the LF only tanks? Otherwise, all your craft look very Kerbal.

Well, this low tech panther/terrier airplane reaches orbit with about 200 LF/O remaining.   When you're dragging the mass of the wings, control surfaces, now-empty tanks etc.  that's only 400 delta V , not enough for anything useful.   By detaching the section containing an FT200 tank, the terrier engine, and the cockpit, pumping all your fuel into it first,   you are drastically reducing the amount of weight that fuel must lift.  You can see we have 1700dV after separating.   This is enough to orbit Minmus.  You can then fly back, dock with the plane again,  re-enter and land normally - everything re-used except the jet engine stage.  I did try visiting biomes by spacewalking but the prograde/retrograde markers went wierd on me, would not have been able to get back i think.

[Sharkman Briton]

1 minute ago, AeroGav said:

Well, this low tech panther/terrier airplane reaches orbit with about 200 LF/O remaining.   When you're dragging the mass of the wings, control surfaces, now-empty tanks etc.  that's only 400 delta V , not enough for anything useful.   By detaching the section containing an FT200 tank, the terrier engine, and the cockpit, pumping all your fuel into it first,   you are drastically reducing the amount of weight that fuel must lift.  You can see we have 1700dV after separating.   This is enough to orbit Minmus.  You can then fly back, dock with the plane again,  re-enter and land normally - everything re-used except the jet engine stage.  I did try visiting biomes by spacewalking but the prograde/retrograde markers went wierd on me, would not have been able to get back i think.

Ah, I see. I personally don't play career mode but this could be very useful for career players!

[NuclearNut]

The multistage planes almost remind me of early 1950's designs for spacecraft.