A few space plane questions.

[Wingnutt]

Walking on water is just as easy as getting a working plane, you just need patience. (wait till winter and walk on the ice)

... You ever want to strangle somebody and buy them a beer at the same time?

[GoSlash27]

Ok, problem #1 is fixed,

I still cant get anywhere close to space, let alone orbit, its an absolute joke how bad it is. I tried the really stupid sounding idea of putting shock cone intakes on the backs of the rapiers because "its bad to have an open node" that resulted in a plane that would not move.

The controls are such garbage that no matter what I do the nose bobbing is present, furthermore, despite the plane flying perfectly straigh with no signs of issues at 20K @1000ms, turning OFF SAS sends it into an uncontrollable spin instantly, it cannot be flown without at high alt and speed.

Im not closer to getting to space than I am walking on water.

Actually, the "Rapier- spike" is a proven concept. It has to be offset so that it doesn't occlude the engine, but it's not really critical to success. Just ditch that for now and we'll revisit it later.

Have you gotten rid of all the unnecessary control surfaces?

*edit* better yet, do you have a .craft file we can play with?

Best,

-Slashy

Edited August 26, 2015 by GoSlash27

[xtoro]

... You ever want to strangle somebody and buy them a beer at the same time?

lol no. But I know lots of people who do

[Wingnutt]

Well I just spent several hours trying a million different things, starting over from scratch numerous times, long story short, it would have been more productive to go find a hobo and let him .... in my mouth.

[adsii1970]

Well I just spent several hours trying a million different things, starting over from scratch numerous times, long story short, it would have been more productive to go find a hobo and let him .... in my mouth.

Actually, and I will share my experiences here, I have actually gotten a lot of enjoyment out of "tinkering" with space plane and aircraft designs. I'm also probably one of the few KSP players that also keeps a spiral bound notebook near my computer when I design a new vehicle. Wing shape, engine type, placement of engines (and tweaking of thrust), air brake placement, key bindings, and even if the craft contains an ejection pod are included in my designs. I even consider thrust to mass ratio, lift, and cargo bay placement when I design.

Sometimes it may take a few hours (or days ) tweaking a design to get the performance I want out of it. Then there are other times when the design just will not work and after considerable time, I start all over again. I still do not consider the failed or flawed design as a waste of time because I've learned what didn't work (and believe me, there has been a bunch of those ).

One of the fun things to remember about KSP is that it is also a platform for experimentation... it's one of the many things I love about this game.

[Nothalogh]

Ive become pretty comfy with rockets and have unlocked enough aerospace to get the RAPIER engines so Ive been tinkering with a space plane, Im trying to start simple, just something to ferry scientists back and forth to my orbiting lab at 125km.

I have a few questions about some quirks I don't understand.

1: Velcro Runway.

For some reason, and ive tried it with multiple craft... the plane will not lift off of the runway until it runs off the end. Not in the sense that it only develops enough lift by the end, more like it is STUCK until the end.. A plane that happily climbs at 100ms.. but even at close to 200ms it will not lift off the runway, then when it reaches the end it leaps off the runway and can climb at 45 degrees for several thousand meters.

This is very frustrating, ive added more lift and more thrust, more and more and more because I thought My plane just wasnt.. plane enough.. the I realized it will just glued to the runway for some reason.

2: Engine performance profiles.

I get that the different engines perform better under certain parameters, currently Im trying to climb as high as possible using the aerospike engines then switching to the Rapiers to transition into space.

Ive read numerous times that I should be getting to almost 40K on air breathing engines before I need to switch to liqud/o2 but I cannot get above 25k without a flameout.. Im using the Ram-air intakes, as I have read those are the defacto best.

In this case there is almost too much info out there, and lots of contradicting advice, I think this may be due to the mass of changes in 1.0. I have read that adding more intakes helps, and I have read that it does nothing. I have read to use basic jet engines to get to the edge of space, and I have read to never use them.. etc etc

Is there a CURRENT chart/graph or something that shows the optimal performance windows for the current engine set?

3: Nose bobbing when adjusting pitch:

This is far and away the most annoying. No matter what I try, different elevator configs, canards, no canards.. the over all control of the aircraft is absolute garbage. when I try to point the nose higher or lower it bobs horribly up in down it does this at any speed and any altitude, and does it even if I switch to precise control (CAPSLOCK). Yaw control is not as bad. I've tried changing the center of lift closer to the center of mass, and further, neither seems to make an appreciable difference.

Thanks again for all the help.

For the ascent profile:

Climb at about 30deg to 9km or so in a supersonic climb

Pitch down to 15deg and ride that to ~20km and (1250m/s with a Whiplash) and (1500m/s with a RAPIER)

Switch on the rockets and close all intakes

Pitch up to about 20 to 25 degrees and push apoapsis to about 72km

Align to prograde and coast clear of the atmosphere

Either circularize there or execute transfer to desired orbit

For the bobbing:

That's SAS being the "found lying by the side of the road" piece of precision engineering it is.

The only real fix is a mod called Pilot Assistant http://forum.kerbalspaceprogram.com/threads/100073

[A_name]

Well I just spent several hours trying a million different things, starting over from scratch numerous times, long story short, it would have been more productive to go find a hobo and let him .... in my mouth.

I would suggest you try “going back to basics†with the following design and take it from there.

-Main body of plane (front to back):

Mk2 cockpit > large MK2 rocket fuel tank > Mk2 to 1.25m adapter > advanced nose cone.

-Engine assembly to be radially attached to main body with 2x mirror symmetry (front to back):

Shock cone intake > Mk1 liquid fuel fuselage > RAPIER engine.

-Wing assembly to be attached to the engine assembly with 2x mirror symmetry:

Delta wing > elevon 4 (***These elevons will be your ailerons to control roll only. Right click on the elevons and turn off yaw and pitch***)

-Control surfaces to be mounted on the advanced nose cone at the back:

Elevon 2 attached horizontally with 2x mirror symmetry (***These will be your horizontal stabilizers as well as your elevators to control pitch. Right click on the elevons and turn off yaw and roll***)

Elevon 2 atatched vertically with symmetry off (***This will be your vertical stabilizer as well as your rudder to control yaw. Right click on the elevon and turn off roll and pitch***)

-Landing gear:

Small landing gear attached with 2x mirror symmetry under the engine assemblies.

Small landing gear attached with symmetry off under the large Mk2 rocket fuel tank.

-Final adjustments

Turn on COL and COM indicators. Use the offset tool (press 2 on your keyboard and then select parts) to move around your engine assemblies, wings and landing gear until COL and rear landing gear are slightly behind the COM.

Use the right click menus to drain the fuel from all your tanks and make sure the COL is still behind the COM. If not adjust accordingly with the offset tool.

Right click RAPIERS and select manual switching.

Bind the ‘toggle mode’ function of the RAPIERS to an action group.

This is all you need for a basic SSTO plane. To fly it, ascend to 10km as steeply as your engines will let you. Once at 10km begin pitching down gradually in 5 or 10 degree increments. Your goal is to reach a speed of around 1200 to 1500 m/s before hitting 20 km. If you hit 20 km and are still going too slow, it means you didn’t pitch down fast enough. You have to give the plane time to get up to speed before it goes higher than 20km where it starts losing thrust due to lack of air. The RAPIERS won’t immediately flame out at 20km. Ride them until you are no longer gaining speed (keep an eye on the speed indicator), hit the action group key you chose to switch to rockets and pitch up to about 30 degrees until your Ap is around 75km then cut the throttle and coast. Drag will cause you to slow down a bit so keep checking your Ap to make sure it stays over 70km, if it drops below that give your engines a small burst. Once at Ap point prograde and circularize. Congratulations, you’re now in orbit!

Once you’ve been able to master this simplest of designs, you can start building upon that to make more complex things that satisfy your particular mission requirements. Good luck!

[GoSlash27]

Well I just spent several hours trying a million different things, starting over from scratch numerous times, long story short, it would have been more productive to go find a hobo and let him .... in my mouth.

WingNutt,

Deep breath. Spacing is hard and we've all been there.

Step #1: Show us a picture of what you have at the moment.

Step #2: Upload a craft file.

Step #3: ???

Step #4: Profit!

We will find what you're doing wrong, explain why it's not working, suggest better ways of doing it, and ultimately help you become a steely- eyed missile man.

Best,

-Slashy

[TronX33]

Blue text will be my responses

Ive become pretty comfy with rockets and have unlocked enough aerospace to get the RAPIER engines so Ive been tinkering with a space plane, Im trying to start simple, just something to ferry scientists back and forth to my orbiting lab at 125km.

I have a few questions about some quirks I don't understand.

1: Velcro Runway.

For some reason, and ive tried it with multiple craft... the plane will not lift off of the runway until it runs off the end. Not in the sense that it only develops enough lift by the end, more like it is STUCK until the end.. A plane that happily climbs at 100ms.. but even at close to 200ms it will not lift off the runway, then when it reaches the end it leaps off the runway and can climb at 45 degrees for several thousand meters.

This is very frustrating, ive added more lift and more thrust, more and more and more because I thought My plane just wasnt.. plane enough.. the I realized it will just glued to the runway for some reason.

As other people said, check your landing gear. It should be at the CoM, or if the craft is really long, behind it, but ow behind the rear-most control surfaces

2: Engine performance profiles.

I get that the different engines perform better under certain parameters, currently Im trying to climb as high as possible using the aerospike engines then switching to the Rapiers to transition into space.

Aerospikes are rocket engines. Try the Whiplash, or the jet engine mode on the rapiers, Also, you should be gaining altitude, yes, but only at about 20-40 degrees (dependin on TWR), then leveling out more to gain speed when the thrust curve on the turbojets and/or RAPIERs kicks, but still at around 10-20 degrees, when you flame-out, switch to rockets, and pitch up more to 30-45 degrees, based on speed and current apoapsis. Yes, some people, like Kore, make SSTOs that get to space on a consistent 35 degree angle, but (no offense) I doubt you're SSTO is based on his design.

Ive read numerous times that I should be getting to almost 40K on air breathing engines before I need to switch to liqud/o2 but I cannot get above 25k without a flameout.. Im using the Ram-air intakes, as I have read those are the defacto best.

In this case there is almost too much info out there, and lots of contradicting advice, I think this may be due to the mass of changes in 1.0. I have read that adding more intakes helps, and I have read that it does nothing. I have read to use basic jet engines to get to the edge of space, and I have read to never use them.. etc etc

All jets flam-out at specific altitudes now. Adding intakes will only help if you can't get to that altitude before running out of air. After that, it becomes useless.

Is there a CURRENT chart/graph or something that shows the optimal performance windows for the current engine set?

3: Nose bobbing when adjusting pitch:

This is far and away the most annoying. No matter what I try, different elevator configs, canards, no canards.. the over all control of the aircraft is absolute garbage. when I try to point the nose higher or lower it bobs horribly up in down it does this at any speed and any altitude, and does it even if I switch to precise control (CAPSLOCK). Yaw control is not as bad. I've tried changing the center of lift closer to the center of mass, and further, neither seems to make an appreciable difference.

That would probably be your SAS's fault, trying to sty at a certain angle, but unable to, or overcompensating. Either that, or you are trying to go at an angle that your thrust does not permit you to, i.e going really far off from prograde in a plane.

Thanks again for all the help.

Edited September 1, 2015 by TronX33

[legoclone09]

I would quicksave before landing, it is NOT fun. when your wing hits the imaginary launchpad 1 km in the air coming in for landing.