SSTOs! Post your pictures here~

[Spartwo]

>snip<

Well yes getting your speed up in the atmosphere will be more efficient,but worth it?.When you have the option of 5-10 minutes less flight time,ease of use,and increased range when refueled in exchange for 15% less mass and increased atmospheric abilities which would you choose?.Of course that's entirely dependant on your playing style which is individual to each player.

[O-Doc]

I just want to add some food for thought. 6 months ago I used to think the secret to SSTO was all about turbo speed at flameout altitude. Now I know, the atmoshperic delta-v game is all about momentum, not speed. The more momentum you can carry the less power you need to accelerate. Because of the effect of drag, you need to put on vertical momentum in the opening section of your ascent profile. Then, when your turbos hit maximum efficiency(25km) you need to add on your horizontal momentum. If you cruise up to 32km at which point you get up to speed, it means that you have no vertical momentum and all your weight saving efforts go to pot when you have to light your rockets to hop out into space, or push fast enough to get your apogee high enough to overcome remaining drag and gravity.

Having said that. if your payload fraction is small, you should not be firing up your rockets until you are well into space anyway.

[ThatNoob]

I want to show my SSTO rocket-thing.

http://imgur.com/a/4RA2c

A crew shuttle bus for getting crew to the station

[KissSh0t]

I want to show my SSTO rocket-thing.

http://imgur.com/a/4RA2c

A crew shuttle bus for getting crew to the station

Just adding it so images show in the thread.

: >

[Rune]

Well yes getting your speed up in the atmosphere will be more efficient,but worth it?.When you have the option of 5-10 minutes less flight time,ease of use,and increased range when refueled in exchange for 15% less mass and increased atmospheric abilities which would you choose?.Of course that's entirely dependant on your playing style which is individual to each player.

If you had twice the climb rate, yes, you would save 5 minutes on the climb, and it sure makes for a more fun handling on low atmosphere, feels much more sporty. I don't deny that! In fact, when I want a fast ascent and don't care about payload (aka crew shuttles), I go for wingless VTOLs, and do fast inefficient rocket takeovers at high angles of attack because I can get over 70kms faster to timewarp. BUT, you don't get an increased range when refuelled, just less range in general (more engine mass, again), so when I go for a big payload (aka cargo shuttle), then I use plenty of wings and a proportionally slightly bigger aviation fuel load to get the most payload out of my engines. Having arbitrarily set, of course, my preferred intake ratio at about 4-1 and therefore my takeover speed at 1500-1600m/s.

The "momentum" comment, I'm just going to ignore, as showing a big lack of understanding as to what momentum actually is and isn't. Sorry but it just makes no sense. Plus you don't look like you want to really consider my arguments much.

Rune. So you could say I use both playstyles. I also know why I use each.

[Judgementus]

Just Tried Making my design work with the lowest Tech I could.

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http://imgur.com/a/hAaXg

Not 100% SSTO but 100% resuable...

Edited February 13, 2014 by Judgementus

[O-Doc]

Plus you don't look like you want to really consider my arguments much.

What? Like "I'm just going to ignore, as showing a big lack of understanding as to what momentum actually is and isn't. [-insert reasons here-] Sorry but it just makes no sense."? Yeah, I considered that argument.

I'm sure people reading this exchange will come to their own conclusions. I have my own data from which I've formed a view. In fact, it might be fun to do some science and set a challenge to find out what the actually answer is. Could be fun!

I'll call it the "SSTO 20/20 Challenge". Prizes for most payload fraction, most delta-v and most delt-v per payload fraction percentage. 20 ton craft minimum, 20% payload fraction minimum.

[Jouni]

I experimented a bit with spaceplanes to see, how much lift really helps.

Consider the SSTO lifters from my earlier posts. The total mass of their turbojets is about 15% of the launch mass or 25% of the dry mass of the ship, including payload. With enough lift, you can probably remove half of the engines and the associated fuel tanks, increasing the payload fraction by a few percentage points (from around 30% to 30-35%). The ship would have less engines than the "1 turbojet per 10 tonnes" guideline many people suggest, but it would not be too underpowered.

There are two important effects of lift during the acceleration: you lose less thrust to fighting gravity, and your intakes work a bit better. This essentially allows you to maintain a higher climb rate during the acceleration. With intake-to-engine ratio 1, the difference isn't too significant, because you are still operating very close to the speeds where re-entry flames start showing up. If you climb too fast, you don't gain enough speed to keep the turbojets running, and the flameout will occur many kilometeres lower at speeds that are several hundred m/s less. You also can't dive down for the final ascent maneuver, because that's a sure way to kill your speed. Overall, winged planes may need a bit less fuel for the rocket stage to reach the orbit, but the difference means at most a percentage point or two higher payload fraction.

Based on this, I would say that the difference between the payload fractions of wingless SSTOs and spaceplanes with intake-to-engine ratio 1 is at most 5 percentage points. The actual numbers are something like 30% vs. 35% for relatively unoptimized designs, and probably a bit higher for optimized ones.

With more intakes, you can accelerate at higher altitudes, where you don't have to constantly balance between ridiculous drag and early engine flameout. This gives you more room to maneuver, and allows having significantly less fuel for the rocket stage. I don't know what the differences between spaceplanes and wingless SSTOs are in this case, because I don't have that much experience with using multiple intakes per engine.

[Rune]

What? Like "I'm just going to ignore, as showing a big lack of understanding as to what momentum actually is and isn't. [-insert reasons here-] Sorry but it just makes no sense."? Yeah, I considered that argument.

I'm sure people reading this exchange will come to their own conclusions. I have my own data from which I've formed a view. In fact, it might be fun to do some science and set a challenge to find out what the actually answer is. Could be fun!

I'll call it the "SSTO 20/20 Challenge". Prizes for most payload fraction, most delta-v and most delt-v per payload fraction percentage. 20 ton craft minimum, 20% payload fraction minimum.

Actually, like the ones I gave before I said I wasn't giving any more. Sorry, but it's not fun anymore. Do your challenge if you want, but the answer is not in your "own data", but in what the newtonian physics ksp is coded on say. You clearly aren't changing your "view" anyhow, so you know, better uses of my time and all that...

[Spartwo]

[Fellow314]

http://i.imgur.com/L1oU91m.png

If it's not actually evil, it definitely looks evil.

[Spartwo]

Everything looks evil when it's black.

[FallingIntoBlack]

Everything looks evil when it's black.

Yeah, a shadow stole my van.

[O-Doc]

What can I say, I'm like a dog with a bone when someone's theories apparently invalidate my empirical data.

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The benchmark loaded Swordfish weighs 149T and delivers a 75T payload(Cuban + Honeypot) to LKO with 631 delta-v before eating into Honeypot reseves. IE; A 50% payload fraction gets over half way to low Minmus orbit.

That's like, you know, physics and stuff.

[Judgementus]

What can I say, I'm like a dog with a bone when someone's theories apparently invalidate my empirical data.

The benchmark loaded Swordfish weighs 149T and delivers a 75T payload(Cuban + Honeypot) to LKO with 631 delta-v before eating into Honeypot reseves. IE; A 50% payload fraction gets over half way to low Minmus orbit.

That's like, you know, physics and stuff.

Nice Doc, (75/149)*100 = 50% payload

When do your Jets Flame out?

And how many Intakes did you use?

I prefer the VTOL SSTO craft to the SSTO Planes due to time, effort, and reliability...but can you do one on a budget and or Tech limits? (please see above)

[O-Doc]

The engine setup is 8 basic jets, 8 turbo jets, and 4 nukes. There are eight intake stakes with 16 rams per stack. The basics die at 28km and the turbos keep powering on with decreasing throttle to about 52km. If you punch the maths on those images you will notice that each MKI fuel pod has under 3L of fuel each.

Like I said before, hundreds of ascent tests. All I want to do is share that wisdom about the basic jet engines.

[O-Doc]

Nice Doc, (75/149)*100 = 50% payload

I prefer the VTOL SSTO craft to the SSTO Planes due to time, effort, and reliability...but can you do one on a budget and or Tech limits? (please see above)

Definitely, I have a range of craft that have either four radials per engine or a ram and two radials. I love the challenge of non-air hogging as much as going for the max-out. My longest range SSTO are two radials and a ram per engine.

[O-Doc]

I've had a look at your parts. If you want to swap in some basic jets then you will get the most efficient ascent profile using an aggressive rocket gravity turn at 10km. Fire your mainsail at 15km(45 degrees) and learn when you are cutting your basics and turbos off. Don't bother with wings unless you are prepared to mount over 30 pairs to haul a jumbo using a non-airhogger with a mainsail rocket.

You won't get close to 50% payload fraction going low tech. My advice is to study the terminal velocity chart and keep testing setups to 15km that will keep your vertical speed on that curve. That's the best place to start to get an idea of your thrust requirements. That, or learn to love some sweet over-sized wing action!

[Spartwo]

If it's not actually evil, it definitely looks evil.

Still look evil?

[Judgementus]

I've had a look at your parts. If you want to swap in some basic jets then you will get the most efficient ascent profile using an aggressive rocket gravity turn at 10km. Fire your mainsail at 15km(45 degrees) and learn when you are cutting your basics and turbos off. Don't bother with wings unless you are prepared to mount over 30 pairs to haul a jumbo using a non-airhogger with a mainsail rocket.

You won't get close to 50% payload fraction going low tech. My advice is to study the terminal velocity chart and keep testing setups to 15km that will keep your vertical speed on that curve. That's the best place to start to get an idea of your thrust requirements. That, or learn to love some sweet over-sized wing action!

I will look at using the basic Jets on my more advanced designs but for the Low Tech model I am using what I can find to be the best weight to power ratio.

However I do need more speed and I think adjusting my flight path to hit 20* at 15km will give me more.

I currently go to 10Km 45* > 15Km 30* > 17.5Km 20* > 20Km+ I Just hold on for dear life...

How about a mini challenge?

• 1 - SSTO (VTOL or Wings) : Unlimited Tech, Max Budget 12,000 (or 12mill if your going by mechjeb) Winner is the person deemed to move the most Payload into 100km Orbit
  
• 2 - SSTO (VTOL or Wings) : Limited Tech (The Lowest Wins), Max Budget 15,000 (or 15mill if your going by mechjeb) Winner is the person deemed to move the most Payload into 100km Orbit with the least Tech Tree Unlocks
  

*Payload - the part of a vehicle's load, from which revenue is derived; passengers and cargo.

So build it and put weight on top to show off how much it can lift.

Air Hogging is allowed but ofc it will really mess up your costings and Stick to STOCK

Edited February 13, 2014 by Judgementus

[Fellow314]

Munshuttle, er, shuttling. To Mun. No refueling required.

Oh, and a shot of the emergency return pod returning, which got quicksaved away.

Oh, and features 'economy' and 'normal' modes. Makes the whole journey in normal mode.

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https://www.dropbox.com/s/vvjl55apj88jjfa/Munshuttle%20NMJ.craft

Oh, and another thing...

It's little brother.

http://i.imgur.com/5yVSKTL.png

(why doesn't that work...?)

Edited February 14, 2014 by Fellow314

[Chirality]

SSTO to anywhere without refueling.

There's a kraken drive in there...

[Overfloater]

How r u people doing xD

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I bet you didn't notice how badly I placed the tail wings

[Armchair Rocket Scientist]

Sorry if this isn't the best place, but plenty of people have been asking questions in this thread, and it seems like people who really know their SSTOs frequent it, so here goes.

I've had decent success with lighter crew SSTOs, but making a heavy cargo SSTO has been giving me a lot of grief.

Here's what I'm trying to make fly:

Its vital statistics are as follows:

Mass (no payload): 67.7 t

Engines: 2X B9 SABRE M (about the thrust of 8 turbojets)

Intakes: 8X B9 SABRE M intakes (comparable to 32 ram-air intakes).

Fuel/Oxidizer balance: 3044 fuel, 2200 oxidizer on the runway.

Wings: 87.7 lift not including control surfaces.

Payload: 20 t

Rocket mode dV: 1335 m/s - actually more since it's lost a little weight by the time it switches to rocket mode.

My ascent profile is as follows: climb at 45 degrees until 15 km, then pitch down until 20 km, at which point vertical speed is 20-30 m/s. Keep vertical speed at 20-30 m/s until engines fall to 50% throttle due to air starvation; this happens at about 1700-1750 m/s and 30-32 km. Switch to rocket mode, pitch up to 45 degrees, slowly pitching down until the vehicle is pointed prograde when apoapsis reaches 70 km. Shut off engines when apoapsis reaches 100 km, and perform periodic small burns to keep it at 100 km until out of the atmosphere. Perform a standard circularization burn at 100 km.

So far, the vehicle runs out of fuel about 200 m/s of dV short.

My goal is to reach a circular 100 km orbit with 500 m/s of dV remaining (not counting reserve jet fuel) and 100 m/s of RCS dV for docking, with a payload fraction of 25%.

How would you recommend I change my design and ascent profile to do this?

[O-Doc]

How would you recommend I change my design and ascent profile to do this?

Keep throttling down at 30-32km and introduce your rockets when your acceleration stops. Keep creeping higher and throttling down to get the most speed possible before killing your turbos and angling back to 45 degrees at full throttle.

You can also try a dipper kick-out maneuver. You will need more elevons for that though.