SSTO Traveling into Orbit Problems

[mojobojo]

Well I am working on getting an SSTO into orbit. I have tried stock crafts on an install of KSP with no mods, and so far I have gotten the Aeris 4A into orbit (once, with not enough fuel to return back). I have been trying to get my own SSTO into orbit and it seems I am having troubles. I seem to feel like I don't know when to throttle down to avoid flame outs. I always thought it was around .10 but sometimes its a bit higher like at .13 - .15. If I don't flame out and flip all over the place my nose seems to start to point down as I get higher and I have no control over it even when I throttle down or use RCS. I have also tried some of the SSTOs from the B9 Aerospace Pack on my install with mods, I am very stable but run out of fuel too fast. I do not know what I am doing wrong.

Here is my ship, maybe a more experienced pilot can tell if its my ship or my crappy piloting.

https://www.dropbox.com/s/13pa5joazy7ekp9/screenshot4.png

Download:

https://www.dropbox.com/s/z21pnc6dbu88u3y/Spaceplane%20Test.zip

Edited July 21, 2013 by mojobojo

[Snooze]

Needs more intakes. Consider adding two pairs of radial intakes near the rear of the plane. Make sure you wings are centered. Throttle down when you get to about .20 air, then slowly throttle it back up until you find the happy medium.

[mojobojo]

Should the wings be exactly centered or is this okay? I moved them down for the landing gear.

https://www.dropbox.com/s/ete9ll1rgmdt26o/screenshot5.png

Edited July 21, 2013 by mojobojo

[bsalis]

Having the wing on the underside should be fine.

However if you put all those air scoops on the underside, the drag will cause it to pitch down.

[mojobojo]

However if you put all those air scoops on the underside, the drag will cause it to pitch down.

I actually hadn't thought about that. I will try putting them elsewhere.

[Snooze]

Two on bottom, two on top. Same drag but symmetrical.

Edited July 21, 2013 by Snooze

[espm400]

The stock drag model in KSP is less than optimal when it comes to space planes as well. If you're serious about them I would really suggest getting FAR (Ferram Aerospace Research). It completely overhauls the drag model of the game and makes space planes a lot more accessible.

It's neither here nor there, but perhaps the biggest assistance I had with my SSTO program was the addition of an XBox 360 controller. KSP doesn't like to recognize the triggers properly, but otherwise it's pretty much plug & play. No more 'on or off' control surfaces.

[mojobojo]

It's neither here nor there, but perhaps the biggest assistance I had with my SSTO program was the addition of an XBox 360 controller. KSP doesn't like to recognize the triggers properly, but otherwise it's pretty much plug & play. No more 'on or off' control surfaces.

I can do that however I had actually thought about getting a nice joystick as long as they are supported.

[sturmstiger]

For your first SSTO I highly recommend using a single jet engine - that would make flameout nearly harmless, and makes its easy for you to experiment with your flight profile near the flameout altitude.

Also note that the ramjet intake is more efficient ("air sucking" / drag ratio) than the other intakes. Three of them per jet engine would make SSTO quite easy, any more would make it TOO easy.

[espm400]

I can do that however I had actually thought about getting a nice joystick as long as they are supported.

Whatever floats your boat mate. I just intensely dislike flying with the keyboard. If you're like me though, and do end up playing with a 360 pad, remember that you'll need a program like Joy2Key to map the triggers to anything. Personally, I like the triggers for throttle control and for some reason KSP doesn't recognize them as a single axis (I could throttle up, but not down).

Anyways, if you run into issues setting up your pad/joystick, or are unfamiliar with Joy2Key (if you require it), just PM me. If I'm sober and available, I shall do what I can.

[Geschosskopf]

I spent most of today trying to make an SSTO and only just now succeeded. I'm so happy, even though the thing serves no practical purpose .

What gave me the breakthrough was watching this video by Das24680. In this, he does a great job of telling you the performance you need to have and the ascent profile. Without those 2 things (plus of course a reasonably stable design), you'll never get there. Here's the video:

The important points are that 1) the rocket engines need to have a TWR of 1.2 minimum, and your jets need to get you to 20km+ doing 1000m/s+ before you kill them, close the intakes, and start the rocket (which all requires action groups). You need to switch from jets to rocket when your intake air gets down to 0.10 (keep the Resources tab open so you'll know when that happens). and for that to happen at 20km or higher, you need beaucoup air scoops.

Lots of repetitive trial and error getting all these ducks in a row. Good luck

[M5000]

The stock drag model in KSP is less than optimal when it comes to space planes as well. If you're serious about them I would really suggest getting FAR (Ferram Aerospace Research). It completely overhauls the drag model of the game and makes space planes a lot more accessible.

It's neither here nor there, but perhaps the biggest assistance I had with my SSTO program was the addition of an XBox 360 controller. KSP doesn't like to recognize the triggers properly, but otherwise it's pretty much plug & play. No more 'on or off' control surfaces.

I can do that however I had actually thought about getting a nice joystick as long as they are supported.

Whatever floats your boat mate. I just intensely dislike flying with the keyboard. If you're like me though, and do end up playing with a 360 pad, remember that you'll need a program like Joy2Key to map the triggers to anything. Personally, I like the triggers for throttle control and for some reason KSP doesn't recognize them as a single axis (I could throttle up, but not down).

Anyways, if you run into issues setting up your pad/joystick, or are unfamiliar with Joy2Key (if you require it), just PM me. If I'm sober and available, I shall do what I can.

All of you, see a post I just made over here. It's a whole thread talking about other peripherals than just KB/Mouse. May have some useful info, as well as a fix posted by sal_vager, for the 360 controller trigger issues.

[espm400]

All of you, see a post I just made over here. It's a whole thread talking about other peripherals than just KB/Mouse. May have some useful info, as well as a fix posted by sal_vager, for the 360 controller trigger issues.

I'll say the same thing I said in that thread, although that fix may be valid, I just think 'Joy2Key' is a much better option. Perhaps I'm biased (I've been using it for games like the DCS series for years), but I've always been of the mentality that if it works, why mess with it?

[M5000]

I'll say the same thing I said in that thread, although that fix may be valid, I just think 'Joy2Key' is a much better option. Perhaps I'm biased (I've been using it for games like the DCS series for years), but I've always been of the mentality that if it works, why mess with it?

The fix certainly is valid, I used it myself!

[ISmokeThis]

I spent most of today trying to make an SSTO and only just now succeeded. I'm so happy, even though the thing serves no practical purpose .

What gave me the breakthrough was watching this video by Das24680. In this, he does a great job of telling you the performance you need to have and the ascent profile. Without those 2 things (plus of course a reasonably stable design), you'll never get there. Here's the video:

The important points are that 1) the rocket engines need to have a TWR of 1.2 minimum, and your jets need to get you to 20km+ doing 1000m/s+ before you kill them, close the intakes, and start the rocket (which all requires action groups). You need to switch from jets to rocket when your intake air gets down to 0.10 (keep the Resources tab open so you'll know when that happens). and for that to happen at 20km or higher, you need beaucoup air scoops.

Lots of repetitive trial and error getting all these ducks in a row. Good luck

Isn't that impossible with jet thrusters alone?

[Silverchain]

Isn't that impossible with jet thrusters alone?

You can go much higher and faster. My heavy planes usually hit 28km at 1600ms-1 using twin turbojets and 2 ram / 8 radial scoops. A purpose built plane can fly at silly heights and speeds on jets.

Be sure to fly at a very shallow angle to pick up speed - I start to level off around 15km, and have the plane moving at a very shallow climb above 20km.

It may help to listen carefully to the engines - when you hear them start to stutter, throttle back a little, then again, then again, until they're practically off, at which point slam on the rockets and ramp the speed back up. You start to get a feeling for when they're gonna flameout.

[LethalDose]

OP, you mentioned your craft flips out. Have you adjusted your CoM and CoL? Looking at your design, I'd guess that your CoM is probably just behind your CoL.

[LethalDose]

I spent most of today trying to make an SSTO and only just now succeeded. I'm so happy, even though the thing serves no practical purpose .

What gave me the breakthrough was watching this video by Das24680. In this, he does a great job of telling you the performance you need to have and the ascent profile. Without those 2 things (plus of course a reasonably stable design), you'll never get there. Here's the video:

The important points are that 1) the rocket engines need to have a TWR of 1.2 minimum, and your jets need to get you to 20km+ doing 1000m/s+ before you kill them, close the intakes, and start the rocket (which all requires action groups). You need to switch from jets to rocket when your intake air gets down to 0.10 (keep the Resources tab open so you'll know when that happens). and for that to happen at 20km or higher, you need beaucoup air scoops.

Lots of repetitive trial and error getting all these ducks in a row. Good luck

OMG that video is horrible. Yes, Get up to max speed on Just jets ~ 20km, but so much else he says in the video is wrong.

DON'T put your gear as far back as possible

DON'T put your gear at an angle to the fuselage (it will cause horrid instability at take off)

After firing his Rockets, he should be climbing much faster until he's out of the atmosphere.

Just... UGH. I think that's the first YouTube video I've ever actually hit dislike one.

[numerobis]

Isn't that impossible with jet thrusters alone?

Typically jets take me to a 75x40 km orbit, which means about 2300 m/s orbit speed at periapsis. Then a short spurt of the rocket circularizes; that part is about 30 m/s. If you build your jet to go fast, you can go 2500 m/s orbital speed. Just 1km/s at just 20km is pretty minimal -- 1 km/s is where turbojets are the most efficient.

Rough guidelines: when you've built your plane, you should have about

1 intake per tonne

1 engine per 15 tonnes

1 Mk2 fuselage per engine

1 small control surface per tonne, or 1 wing connector for every 2 tonnes, or 1 swept wing for every 3 tonnes (mix and match)

With more wingspan and fuel you can ease up on engines.