Longer runway?

[Tex_NL]

Another 1000m might as well be another 2500m. It  would STILL not be enough for many.

But I find it strange I can whip up a 200+ tonne plane in about 30 minutes that CAN take off before running out of runway and you can not. And no, it was NOT overpowered as it had just eight Rapiers.

Edited January 1, 2017 by Tex_NL

[Kergarin]

3 hours ago, Tex_NL said:

Another 1000m might as well be another 2500m. It  would STILL not be enough for many.

But I find it strange I can whip up a 200+ tonne plane in about 30 minutes that CAN take off before running out of runway and you can not. And no, it was NOT overpowered as it had just eight Rapiers.

The point is: you are absolutely misunderstanding us.

We CAN do this too. That's easy and not the point.

Double it to 400+ tons or even more and that's still no problem to take of on the stock runway. Or what do you think does this weight?

 

We are just perfectionists, who want to build these things more efficient and less overpowered or overwinged than its possible on that short runway.

 

Edited January 1, 2017 by Kergarin

[OHara]

Games like this are fun because they are just challenging enough to be interesting.

A plane with just enough wing-area and thrust to support its weight at 3° incidence at 500m/s, does need some extra design feature to take off and land in 2.5km (plus the descending glide over they bay).  It could be an engine with good low-speed thrust, or flaps (to the small extent they help in stock aero with non-interacting wing parts) or gear positioned to give the wing 15° AoA, or rocket-assist, or just larger wings chosen as a compromise to best serve the whole flight envelope, and then maybe arresting chutes for landing.  

These challenges appeared just about when I was ready to deal with them, so 2.5km might be just about right.

Some other area to use for specialized aircraft might be nice.  Specialized aircraft use dry lake-beds.  In KSP we have the ice caps at the poles, if we somehow teleport there.   A dry fossilized tidal flat south of KSC might be nice.

[Kergarin]

4 minutes ago, OHara said:

Games like this are fun because they are just challenging enough to be interesting.

A plane with just enough wing-area and thrust to support its weight at 3° incidence at 500m/s, does need some extra design feature to take off and land in 2.5km (plus the descending glide over they bay).  It could be an engine with good low-speed thrust, or flaps (to the small extent they help in stock aero with non-interacting wing parts) or gear positioned to give the wing 15° AoA, or rocket-assist, or just larger wings chosen as a compromise to best serve the whole flight envelope, and then maybe arresting chutes for landing.  

These challenges appeared just about when I was ready to deal with them, so 2.5km might be just about right.

Ok. That's the first argument that really hits me, because I like to and want to be challenged 

[foamyesque]

4 hours ago, UnusualAttitude said:

This is way too dismissive. OK, you shouldn't need a longer runway for most reasonably sized designs (tens of tonnes), but runway length for larger designs is an issue, and the suggestion of a longer runway is a perfectly reasonable one.

I'm no stranger to designing large airframes, and I regularly encounter the following problems:

- Lack of large (long) landing gear, making tail-strike a real challenge on long, sleek airframes. This is not an issue of landing gear placement in relation to CoM. I can get my aircraft to rotate, it just can't reach sufficient incidence to become airborne without a ridiculously high TWR.

 

I don't agree. I am also no particular stranger to large aircraft. In my experience, the XL landing gear are plenty large for just about every purpose (I at one point had a 2000t craft launching on them) and the length of the runway doesn't actually make as much difference with mass as you might think; it's a question of thrust:mass, thrust:drag, and lift:mass ratios, not absolute mass.

It's easier to get higher ratios for smaller craft because the structural considerations (joint strength, etc) are so much simpler to deal with, but dial down a Juno to 0.25 TWR and watch how long it takes a light plane to take off

[Tex_NL]

36 minutes ago, OHara said:

A plane with just enough wing-area and thrust to support its weight at 3° incidence at 500m/s, does need some extra design feature to take off and land in 2.5km (plus the descending glide over they bay).  It could be an engine with good low-speed thrust, or flaps (to the small extent they help in stock aero with non-interacting wing parts) or gear positioned to give the wing 15° AoA, or rocket-assist, or just larger wings chosen as a compromise to best serve the whole flight envelope, and then maybe arresting chutes for landing.

That's is not a plane. But rather an air breathing horizontal rocket. You do not launch rockets from the runway. You launch them from the launchpad.

[foamyesque]

5 minutes ago, Tex_NL said:

That's is not a plane. But rather an air breathing horizontal rocket. You do not launch rockets from the runway. You launch them from the launchpad.

Such designs don't have a TWR > 1. If they did they'd be able to take off from the runway, too.

[UnusualAttitude]

1 hour ago, Tex_NL said:

But I find it strange I can whip up a 200+ tonne plane in about 30 minutes that CAN take off before running out of runway and you can not.

Good grief... 

@Kergarin is merely stating that a longer runway would allow him to implement different designs that would be difficult or impossible with the existing one. This requires no new part to be added, it would have no impact on the performance of the game and would require minimal dev input (just a modification to the top-tier KSC), and allow the players who want to use it do some cool new stuff.

Unless you consider limited runway length at top-tier to be a gameplay mechanic (makes sense, I suppose, but a shame for sandbox players and replica builders), I really don't see what the problem is.

Edited January 1, 2017 by UnusualAttitude

[GoSlash27]

280t SSTO spaceplane launching from the runway on 8 RAPIERs.
 

Spoiler

 

 

 

 

It can be done, even with extremely low t/w and you don't need any special techniques to make it happen. This is a t/w of 0.3; well below what would be optimal for payload fraction or cost per tonne to orbit. If I can do it with something this underpowered, you should be able to do it with something sane.

Best,
-Slashy

Edited January 1, 2017 by GoSlash27

[Kergarin]

1 minute ago, GoSlash27 said:

280t SSTO spaceplane launching from the runway on 8 RAPIERs.
 

  Hide contents

 

 

 

 

 

It can be done, even with extremely low t/w and you don't need any special techniques to make it happen.

Best,
-Slashy

That's an absolutely impressive plane

And this design might be perfect if you want to stay in kerbin orbit, but what if you want to go further out? All those wings become dead weight, and how much do they all weight together? That's just what I would like to avoid 

One or two pairs of big-s wings would be enough for this size. (having only two pairs plus one pair of big-s tailfins as elevators on my ~440ton SSTO)

[GoSlash27]

Kergarin,

 I just knocked this one together as a proof- of- concept to demonstrate that underpowered designs can still launch from the runway and make orbit. Answering your questions...

-I would prefer to use the BigS wings, but they don't have the heat tolerance necessary for SSTO work.

-I never design SSTO spaceplanes to go farther than LKO because airplanes make lousy spaceships, but I understand that many don't share my philosophy.

-Surprisingly, wings account for very little of the total mass. About 7.5t in this example. Peanuts compared to the 282t takeoff weight or the 100t of payload it can put in orbit.

Best,
-Slashy

 

[Nothalogh]

15 hours ago, JadeOfMaar said:

Care to expand on this? I'm curious. I build hypersonic planes

 

Less wing equals less drag at operating speed and altitude, less wing also necessitates either more engines or a longer takeoff roll.

I have worked around this problem by using rocket powered runway sleds

Edited January 1, 2017 by Nothalogh

[GoSlash27]

6 minutes ago, Nothalogh said:

 

Less wing equals less drag at operating speed and altitude, less wing also necessitates either more engines or a longer takeoff roll.

I have worked around this problem by using rocket powered runway sleds

 Actually, not so much, as I have demonstrated here. Wings account for very little of the overall drag. If you use less wings, you will need more incidence. If you use more wings, you need less incidence. The difference between the two is negligible in terms of total mass or drag, so it's worth it to just go ahead and add the extra wings.

Best,
-Slashy

[Adelaar]

I'll just leave this here:

I use these RATO's on my heavy lifter, which at max load just doesn't have the power to get itself airborne before the end of the runway. They are fully recoverable, minus the spent fuel. So technically not an SSTO, but in that aspect most of my spaceplanes aren't SSTO's (as they often carry small droptanks to minimize the need to carry LF around, which actually increases overall dV).

 

 

[foamyesque]

46 minutes ago, GoSlash27 said:

-I would prefer to use the BigS wings, but they don't have the heat tolerance necessary for SSTO work.

Say what? They have the same 2400K tolerance as the wings you were using.

Edited January 1, 2017 by foamyesque

[JadeOfMaar]

16 minutes ago, Nothalogh said:

 

Less wing equals less drag at operating speed and altitude, less wing also necessitates either more engines or a longer takeoff roll.

I have worked around this problem by using rocket powered runway sleds

Okay then. I tend to build my craft with buffs...I spend so much time designing something that's fairly flashy and still works that I can't stand the drawn-out low-altitude warm-up phase of typical launches.

[OrbitalBuzzsaw]

Maybe the T1 runway is 1/2 as short as the T2 runway but reasonably smooth, and the T2 runway is the same size as the normal runway, and the T3 runway is 1.75 as long as the normal runway and. Also, maybe a second runway running at a 45 degree angle, crossing over KSC 05/27, but it can only go up to T2, and you have to build it. And a second Launchpad with the same restrictions, at that rate.

Edited January 1, 2017 by OrbitalBuzzsaw

[GoSlash27]

8 minutes ago, foamyesque said:

Say what? They have the same 2400K tolerance as the wings you were using.

The airliner main wing? My .cfg from 1.2.2 shows a 1,200° heat tolerance. Am I missing something?

 

 

[foamyesque]

26 minutes ago, GoSlash27 said:

The airliner main wing? My .cfg from 1.2.2 shows a 1,200° heat tolerance. Am I missing something?

 

 

Big S parts are the spaceplane delta, strake, elevons, and tailfin. You're thinking of the FAT ones.

[JadeOfMaar]

27 minutes ago, GoSlash27 said:

The airliner main wing? My .cfg from 1.2.2 shows a 1,200° heat tolerance. Am I missing something?

You're confusing the Big S spaceplane wing parts (which have 2400K tolerance) with the FAT-455 airliner wing parts which have 1200K.

 

29 minutes ago, OrbitalBuzzsaw said:

Maybe the T1 runway is 1/2 as short as the T2 runway, which is 2/3 as short as the T3 runway, which is 1.75x as long as the current runway. Also, maybe a second runway running at a 45 degree angle, crossing over KSC 05/27. And a second Launchpad, for polar launches, at that rate.

By default, a craft's orientation in the VAB is for polar launches. i'd like to see how, if implimented, the second runway clips the first one.

Edited January 2, 2017 by JadeOfMaar

[EpicSpaceTroll139]

 

10 hours ago, UnusualAttitude said:

<snip>

- FAR, <snip>

No, it's not. It is about 2,5 kms long, which is regional airport size. Major international airports are 3-3,5 km or more, and some of the major test flight facilities (Istres in France) have 5 km.

I'd be interested if anyone could name one real life large delta design (>100 tonnes) that can take off in less than 2,5 km at max weight..?

You mention FAR. Why would a longer runway be added to stock to deal with the difficulties that a mod introduces? If you're using mods you might as well use KerbinSide for its longer runways.

And on the runway length: Lets not forget that Earth has real aerodynamics (similar to but more complex than FAR), which (usually) require higher speeds for flight, and Earth is 10x the size of Kerbin (Kerbal stuff in general is smaller too). If you scaled up the Kerbal runway to equivalent size on Earth, it would be enormous.

While making the KSC runway longer couldn't hurt, I'm inclined to think that if a stock plane in stock physics can't take off from the current one, there is something flawed in its design. The only things I haven't managed to get off the runway are things that... well... they weren't gonna fly anyways.

Actually there is one exception, that being a prototype for my Yumbo Yet 6000.

Spoiler

But I don't think it was realistic expectations for the runway to be designed for this kind of thing ^

Still didn't stop me from making it work.

 

Edited January 2, 2017 by EpicSpaceTroll139

[GoSlash27]

1 hour ago, foamyesque said:

Big S parts are the spaceplane delta, strake, elevons, and tailfin. You're thinking of the FAT ones.

foamyesque,

 Yeah you're right. I would love to have access to the FAT wings for jumbo spaceplanes, but the lack of heat tolerance makes it a dicey proposition.

 All of this is getting away from my main point, which is this: Don't be afraid to add wings to your space plane if it needs them. The penalty for doing that is very slight in terms of drag and mass. A large wing with lower incidence makes almost exactly the same drag as a small wing at high incidence and wings represent a miniscule percentage of the total mass.

 You really don't want to compensate for insufficient wings with "moar boosters". Engines are very heavy compared to wings, and SSTOs don't do you any good if you can't land them safely. Trust me; you can still build a successful SSTO with adequate wing area even if your t/w is ridiculously low. The wings themselves aren't heavy or draggy enough to keep that from happening. The best solution to "insufficient wings" is "moar wings".

 

 

Best,
-Slashy

Edited January 2, 2017 by GoSlash27

[tseitsei89]

On 1/1/2017 at 5:34 AM, Kergarin said:

Hello, 

Would it be possible that the runway not only gets broader and less bumpy by upgrading it, but also gets longer? 

 

Sadly, the minimum required number of engines (EDIT: and lifting area) on all of my spaceplanes is defined by the number of engines required to reach takeoff speed until the end of the runway, while the number of engines needed to get to orbit would alwaysbe lower.

 

That means we could build much more efficient planes, if the runway was longer.

 

So please think about a longer runway, at least at the highest upgrade level. 

Or then maybe (just a thought though) you could learn how to build (space)planes... How much mass can you get to orbit with 1 rapier? Since I honestly believe that the problem is not the length of the runway but rather the way you engineer your aircrafts.

If you can get 30+ tons in stable orbit with ONLY 1 rapier you know what you are doing but if it is lower (or even a similar number to that) I find that the problem is your own design and not the length of the runway...

In my experience the limiting factor is breaking Mach1. If you can get above that speed you start getting s**tloads of thrust. And in my personal experience that takes significantly more engines than just the takeoff...

[ThaZeus]

You guys have to remember that kerbin is like 1/10 the size of earth.

[GoSlash27]

6 hours ago, tseitsei89 said:

If you can get 30+ tons in stable orbit with ONLY 1 rapier you know what you are doing but if it is lower (or even a similar number to that) I find that the problem is your own design and not the length of the runway...

tseitsei89,

 To be fair, just because you can operate at that end of the t/w scale doesn't necessarily mean that you *should*. I often experiment at extremely low t/w for research into drag reduction techniques, but my practical SSTOs have higher t/w.

Happy New Year,
-Slashy