SSTO's :)

[Secuas]

I've been at KSp for a long time now. But there's one thing left unknown for me. I can't fly spaceplanes.... Not at all. I know all about the center of lift behind center of mass thing, i tried using mechjeb. read so many things... I think my designs are good and all I want is the ship to be cabable of reaching my kerbin station (maybe the mun) and drop off some cargo. But the same thing happens over and over again. I reach about 60.000 km height, run out of fuel and crash down. I'd love to get into SSTO's but I can't make them work. All help is welcome . Do I really suck at planes or is there something else? Thanks in advance ^^

Edited November 7, 2014 by Kaname

[Wanderfound]

I've been at KSp for a long time now. But there's one thing left unknown for me. I can't fly spaceplanes.... Not at all. I know all about the center of lift behind center of mass thing, i tried using mechjeb. read so many things... I think my designs are good and all I want is the ship to be cabable of reaching my kerbin station (maybe the mun) and drop off some cargo. But the same thing happens over and over again. I reach about 60.000 km height, run out of fuel and crash down. I'd love to get into SSTO's but I can't make them work. All help is welcome . Do I really suck at planes or is there something else? Thanks in advance ^^

Have a poke at the piloting guide in post #2 of the Kerbodyne thread linked in my sig. It was written for FAR/NEAR, but the same basic flight profile applies in stock as well.

99% of my designs are built for FAR, but see https://www.dropbox.com/s/lbnz9s8k9h7gwgb/Kerbodyne%20Benchmark%20StockAir.craft?dl=0 for something that works in stock.

Edited November 4, 2014 by Wanderfound

[doggie015]

A vertical launch pure rocket SSTO would be easier. You need big tanks and small engines. The closer you can get the launch thrust to weight ratio to 1.01 the better.

Slap a Mk16 parachute onto a Command Pod Mk1 then put that onto a decoupler then an inline advanced stabilizer then put that onto a Rockomax X200-32 fuel tank and balance the whole lot onto a LV-T30 engine - There is no cargo capacity on it but it should get you used to SSTO design and flying it into orbit and back

[Secuas]

Thanks Wanderfound for the desgin ^^ I tried it and after 20.000 km i can use mechjeb ascent guidence and works good. I was so excited i took your craft and made my own version wich can hold cargo. Fuel is still a bit of an issue tho. It just barely made it into orbit. All i want it to do is bring cargo to my station.

[Wanderfound]

Thanks Wanderfound for the desgin ^^ I tried it and after 20.000 km i can use mechjeb ascent guidence and works good. I was so excited i took your craft and made my own version wich can hold cargo. Fuel is still a bit of an issue tho. It just barely made it into orbit. All i want it to do is bring cargo to my station.

http://i.imgur.com/JtIM0PN.jpg

Glad to hear you're having fun.

Give up on using Mechjeb in atmosphere (MJ is good in space, but it's a lousy airplane pilot) and fly it manually as per the instructions in the piloting guide I mentioned. It should be able to hit orbit with plenty left in the tanks.

It's all about extracting as much speed and altitude from the jets as possible before you switch to rocket mode. Turn the RAPIERs off the second that they switch to closed cycle, and don't turn them back on again until the turbojet starts to die as well.

If you do it right, you should be able to get it over 30,000m and 2,000m/s before you start burning oxidiser.

[Secuas]

One last question, when I turn off my Sabre's after about 20.000 because they flame out I turn them off and use the turbojet alone. I level out at out 10 degrees (pitch) and my ship passes the AP and it starts dropping again. Could it maybe be too heavy for just a single Turbojet since I've put in a bit of cargo now?

Edited November 4, 2014 by Kaname

[Wanderfound]

One last question, when I turn off my Sabre's after about 20.000 because they flame out I turn them off and use the turbojet alone. I level out at out 10 degrees (pitch) and my ship passes the AP and it starts dropping again.

Yup, that'll happen. But you have to keep in mind that an atmospheric apoapsis is a very movable thing; as soon as you get the plane climbing again, your apoapsis will be right in front of you.

Firstly, the nose drop is probably largely due to losing the vectoring ability of the RAPIERs when you turn them off. You can counter this by just pulling back on the stick and holding the nose up with the canards and other control surfaces; that's what they're for. A Vernor or two under the nose can also help to brute-force it if you're having trouble keeping the nose up.

Secondly. the climb rate of a plane is chiefly dependent on three factors: Angle of Attack (AoA), altitude and speed. As you go faster, the AoA required to maintain a given climb rate decreases. However, as you go higher, the AoA required to maintain a given climb rate increases. Your plane is descending because you have insufficient speed to maintain a climb at that altitude and AoA. So, either increase the AoA (by pulling the nose up, as described in the above paragraph) or increase the speed. Fortunately for you, planes tend to accelerate quite easily when they're in a dive...

If you keep the 10° pitch, your descent should eventually level out and turn back into a climb as you speed up. The drop is only really a problem if you end up descending so far that the atmospheric drag starts to slow you down again.

Incidentally, "turn the RAPIERs off when they switch modes" is a simplified version that isn't as efficient as possible. A bit more complicated (but better) is to toggle off the turbojet as soon as the RAPIERs begin to sputter but before they switch modes. Then run the RAPIERs alone until they do switch modes, then disable the RAPIERs and reengage the turbojet. Then, when the turbojet begins to stutter, leave the RAPIERs off and gradually throttle down in order to keep the air intake requirement just below what is available. Once you can't throttle down any more without completely throttling off, fly like that until the turbo dies or the plane starts to slow. Then turn the RAPIERs back on.

Basically, constantly adjust the number of engines to match the intake air available, and get every last metre of speed and altitude before switching to rockets. Also, keep the turbojet on for the final ascent: even if it's already choked from lack of air, the rockets will drive a ram-air effect that should let you get a bit more thrust out of it. After that, once the turbojet finally chokes for good, close your intakes to minimise drag.

BTW: as you may have heard many folks say, if you're getting into aircraft then it is very much worth giving NEAR or FAR a try. Aircraft are vastly more fun to fly with a sensible drag model and realistically thin and slippery air. A lot of the drawn-out plowing through the atmosphere that characterises a stock spaceplane ascent is caused by the soupmosphere rather than anything innate to spaceplanes. With more realistic aero, it's quite easy to get from runway to orbit in five minutes.

[Secuas]

Thanks! I kind of figured out myself what was wrong, i didn't build enough speed and I was going way to steep. I got it in obit with a little cargo!!!!! EVEN WITH MOAR FUEL LEFT. This has been my next achievement in KSP. Thanks again +all rep i could find

(don't mind the huge plane that is on my station it's the defeult one wich just got added i got it up there with alot of hassle)

(I forgot a airplane girder so it kinda looks a bit derpy)

Next challange....... Landing XD ah i'll figure it out i got DRE btw so.. extra hard.

What pitch do you recommend for re-entering? scratch that i used 15 degrees worked fine.

Edited November 4, 2014 by Kaname

[Wanderfound]

Cool.

Next step, NEAR/FAR; after that, RPM and IVA flying...

Edited November 4, 2014 by Wanderfound

[Secuas]

Still need to prachtise on that....

[Wanderfound]

http://i.imgur.com/XJAZnCH.jpg

http://i.imgur.com/3WBhVfZ.jpg

Still need to prachtise on that....

Perhaps a slightly shallower reentry. And get some practice in before you try DRE...

[Secuas]

Here's my latest design. Without your help i wouldn't have got this into orbit.(and having it rendez-vous with my station) It has a cargo bay and a crew module.

Edited November 4, 2014 by Kaname

[Redshift OTF]

Welcome to the SSTO club!

[Secuas]

Check out my new tiny interplanetary SSTO's I'm really getting the hang of this

It took me an entire day to design this and it has been payed off. It depending on how you fly it, it can barely reach my 100 km Kerbin station. But works great for me.

I proudly present: The Atomic Yuki.

http://imgur.com/a/6ES37#1

Edited November 7, 2014 by Kaname

[Alshain]

Very nice. Keep it up!