Does it still count as an SSTO?

[michaelphoenix22]

I built a space plane capable of getting to 80 km and circularized however in order for it to get off of the runway it requires a couple of SRBs. If the runway was about 50 ft longer or had a little ramp at the end i could get off no problem....

However because i run our of runway i need a little more oomph to get off the ground.

[Johnno]

As long as you don't drop them it's an SSTO.

[Xellith]

I built a space plane capable of getting to 80 km and circularized however in order for it to get off of the runway it requires a couple of SRBs. If the runway was about 50 ft longer or had a little ramp at the end i could get off no problem....

However because i run our of runway i need a little more oomph to get off the ground.

Single Stage To Orbit. Doesn't count if you detach them, otherwise yes.

[Tex_NL]

Johnno is correct. SSTO stands for Single Stage To Orbit. Anything that gets to orbit without any staging (launch clamps excepted) can be considered an SSTO. It does not have to be a plane.

To get airborne easier you might want to move your main landing gear closer to the center of mass making it easier to lift the nose. Just watch out for the ever present risk of tail strike.

[Moon Goddess]

A lot of people around here seem to have the impression that SSTO means spaceplane. They are different concepts.

Basically, if you don't hit the space bar more than just to launch, it's an SSTO. Even if vertical launch.

[RoboRay]

If you can't get off the runway before it ends, it's the craft's design not the runway's design that's the problem. The usual issue is that the center of mass is too far forward of the rear landing gear, leaving the flight controls with insufficient leverage to raise the nose.

[Tiron]

I built a space plane capable of getting to 80 km and circularized however in order for it to get off of the runway it requires a couple of SRBs. If the runway was about 50 ft longer or had a little ramp at the end i could get off no problem....

However because i run our of runway i need a little more oomph to get off the ground.

Problems getting off the runway are usually caused by the placement of your main landing gear. It's a leverage thing. In flight, the 'fulcrum' of your craft is the center of mass. But while you're on the runway trying to get the nose up, it's the rearmost set of landing gear that touch the ground while level (so tail bumper gear don't count.)

So what happens is, if your rear landing gear are too close to the control surfaces, those control surfaces have very little ability to lift the craft because they've got almost no leverage.

So what you want to do is move the rear landing gear forward. The further forward they are, the easier it'll be to get the nose up. But also the more likely you are to have a tailstrike. So you have to balance the two. The key thing is you don't want them inline with your control surfaces!

If you're not opposed to mods, you can ease things a bit with TT's modular multiwheels pack, which has a whole bunch of very useful landing gear that are taller and tougher than the default ones, and have a suspension to boot (which helps a LOT landing on rough terrain). Some of them also have very weak built in motors. And there's even a cute little tailwheel which is just awesome for preventing tailstrike damage.

[michaelphoenix22]

thanks for the advice about the wheel mod pack... it actually solved a couple of problems i was having with my launch. Getting higher off the ground gave me a lot more flexibility in how i launch and i was able to ditch the SRBs!

[Tiron]

thanks for the advice about the wheel mod pack... it actually solved a couple of problems i was having with my launch. Getting higher off the ground gave me a lot more flexibility in how i launch and i was able to ditch the SRBs!

Glee! Yeah, I freaking LOVE those landing gear. I actually downloaded it hoping the rover wheels worked better, and fell in love with the landing gear instead.

[michaelphoenix22]

some pics

[Epthelyn]

I'm not sure about more "oomph" (from engines) so much as 'More wings'. You're trying to lift a fairly heavy vehicle there.

[Tiron]

I'm not sure about more "oomph" (from engines) so much as 'More wings'. You're trying to lift a fairly heavy vehicle there.

Well he said he needed 'More Oomph' to get it off the runway, not just to climb...he's got enough thrust there that it's flying more off the thrust than the wings, certainly. Just didn't have enough lift or the landing gear placement evidently, to be able to get it pointed up enough to fly on the thrust.

I guess the higher landing gear and different placement solved that... heh. Interesting design. Are those the hybrid engines from the B9 pack?

[michaelphoenix22]

it flies perfectly now that i was able to get more height from the wheels as opposed to the stock small gear bays i was using. I can risk pullin gup sooner now. Before i had to wait until the very end of the runway. If i was going too slow i wouldnt be able to pull up in time. Thats why i needed the SRBs. now with the taller wheels i can afford to pull up earlier and it looks like a much more professional launch as opposed to the 25% success rating cross your fingers launch i was doing.

and yes they are the B9 hybrids

[magnemoe]

A lot of people around here seem to have the impression that SSTO means spaceplane. They are different concepts.

Basically, if you don't hit the space bar more than just to launch, it's an SSTO. Even if vertical launch.

And no you can not click on decoupler and press decouple neither use mechjeb autostage, not even undocking docking ports is legal

Not saying its an bad idea, in real world with current engines something like an reuseable falcon 9 or an two stage space plane makes more sense than an ssto and will probably be an cheaper way to put things in orbit.

[Ekku Zakku]

Another way to help with getting off the ground quicker on such a limited runway (this works with atmospheric engines only) is to spool them up for a short time while holding the brakes, that way when you start rolling you already have more thrust at your disposal. I don't know if it applies to your plane or not, or if it does whether you're already doing it, but I thought I'd add my 2 cents for anybody else who comes across this thread =3 but definitely the wheel placement is the most important, provided the plane can provide enough lift at takeoff speed (I actually run into the problem of putting them too far forward sometimes and end up tilting backwards when sitting still!)

As for SRB-assisted takeoff, I would go with the little sepatrons instead of the larger ones; they weigh so little when empty and provide a great TWR, thus you can keep them on and call your plane an SSTO! They're just like JATO rockets lol

[Tiron]

Another thing that helps: Forward Canards. It's the leverage thing again. The Canards end up being so far forward of your rear landing gear they get a LOT of mechanical advantage as a result, meaning that even a single pair can make it MUCH easier to get the nose up.

[katateochi]

My only issue with SRB's is they can't be refuelled and the way I see it, the point of an SSTO is being able to land, get refuelled and then take off again (without reloading the craft or using hyperedit to refill it). Rather than use septrons or SRB's I've sometimes used those small radial orange engines mounted on the nose cone facing down and bound them to an action group. A quick blast from them drives the nose up and its totally refuelable (via KAS fuel truck or the like).

[Tiron]

My only issue with SRB's is they can't be refuelled and the way I see it, the point of an SSTO is being able to land, get refuelled and then take off again (without reloading the craft or using hyperedit to refill it). Rather than use septrons or SRB's I've sometimes used those small radial orange engines mounted on the nose cone facing down and bound them to an action group. A quick blast from them drives the nose up and its totally refuelable (via KAS fuel truck or the like).

You can usually solve the problem without needing booster rockets just by fiddling with your landing gear placement, though.

And the ability to refuel solids has been talked about...it may happen in future.

[Ekku Zakku]

My only issue with SRB's is they can't be refuelled and the way I see it, the point of an SSTO is being able to land, get refuelled and then take off again (without reloading the craft or using hyperedit to refill it). Rather than use septrons or SRB's I've sometimes used those small radial orange engines mounted on the nose cone facing down and bound them to an action group. A quick blast from them drives the nose up and its totally refuelable (via KAS fuel truck or the like).

They can't be refueled per se, but irl it would be quite easy to swap them out for another set while the liquid fuel is filling up. Considering how it's not very feasible to refuel an SSTO repeatedly (having to put out fuel tanks, leaving them sitting around lagging KSC, then replace them anyways when they're empty), I'm fine with calling sepatrons "reusable" and just reloading the craft. To each their own!

I do want to develop an SSTO that will carry half an orange tank of payload to orbit, and make it refuelable on the ground as well, but I'm waiting for the game to get closer to being finished. With my previous experiments developing one though, I did have trouble getting enough speed to leave the runway with any lift, so there would be no way for me to use sepatrons if I do want to refuel on the ground.

[magnemoe]

An fully reusable SSTO who you fill with cargo on ground is fun but pretty unpractical. Makes far more sense on Laythe however here it will primary be passengers.

[Ekku Zakku]

An fully reusable SSTO who you fill with cargo on ground is fun but pretty unpractical. Makes far more sense on Laythe however here it will primary be passengers.

It is practical as you don't have to build the payload on the SSTO, and instead you can load it onto the runway then load it onto the plane. It'll also be a great way to save money in campaign mode, all you need to do is pay the cost for the fuel and tanks (and a way to move it), rather than load a new SSTO which also has the cost of the engines and cockpit and all that. Granted, that won't be much of a problem with reclaiming vessels at KSC, but it might make a difference to some players.

[michaelphoenix22]

Well he said he needed 'More Oomph' to get it off the runway, not just to climb...he's got enough thrust there that it's flying more off the thrust than the wings, certainly. Just didn't have enough lift or the landing gear placement evidently, to be able to get it pointed up enough to fly on the thrust.

I guess the higher landing gear and different placement solved that... heh. Interesting design. Are those the hybrid engines from the B9 pack?

I originally designed this plane with the intent of being able to take off from the ground with a rover or satellite drop it off and return without the need for staging or complex launch vehicles. In addition it is practice for future campaign mode. This is the reason for the excess thrust.The ability to take off and deliver small payloads without sacrificing a number of boosters and fuel tanks for every launch would be invaluable.

[Geschosskopf]

Just a suggestion here to help getting off the runway in the future....

I've been finding it advantageous to make my spaceplanes as tail-draggers. Not only does this give them a nice nose-high attitude while still on the ground but you can save a bit of weight because you only have 2 big wheels and 1 little wheel instead of 3 big wheels (although you need a mod that has tailwheels, such as Firespitter or TT's Modular Multiwheels). Tail-draggers tend to fly themselves off the runway without any control input before they pass the taxiway to the SPH.

Of course, being a tail-dragger rather spoils the futuristic look of the thing, and isn't always possible anyway. Life for a delta-wing thing, you'd probably have to put the main gear on long outriggers sticking out in front, which might end up weighing more than tricycle gear (besides being butt-ugly). But it's great when you can do it and don't care about looks.

[RoboRay]

You can achieve a similar nose-up ground attitude with tricycle gear, if you attach the rear wheels higher up on the airframe than the nose wheel.

Here, the nose wheel is attached to the bottom of the fuselage, while the rear wheels are on the bottom of the wing. This also contributes to ground stability by providing a wider wheel-base.

This results in significantly more lift production while rolling down the runway, allowing shorter take-off rolls at lower speeds. The SSTO craft shown can be airborne before even reaching the taxiway intersection.

Edited August 22, 2013 by RoboRay