Better SSTO Spaceplane Challenge (0.23.5+0.24) Fin!

[Sirine]

That will need to be 26 hours later. Currently not having computer at hand.

[Sirine]

@Wanderfound OP updated as per your request.

[DaMichel]

Thank you Sirine. I appreciate this, too.

Beside, I'm willing to get B9 and IR to test more planes. On the other hand i'd like to suggest to my fellow participants to remove non-essential mod parts - like for cargo stuff, lights and so on. (hi kklusmeier ) I'd love to see additional stripped crafts for download.

[WafflesToo]

Thank you Sirine. I appreciate this, too.

Beside, I'm willing to get B9 and IR to test more planes. On the other hand i'd like to suggest to my fellow participants to remove non-essential mod parts - like for cargo stuff, lights and so on. (hi kklusmeier ) I'd love to see additional stripped crafts for download.

I could do that. I'm only using IR for the hinge block in the cargo bay. I'll update the craft file tonight.

EDIT:

Done, removed the IR bit from the plane

Edited August 28, 2014 by WafflesToo

[Sirine]

There is one thing I would like to ask for all the participant.

Since the vote are public, every one can see who you vote for.

And hence, would you please share a word to two about "why" you choose your vote to that particular SSTO space-plane.

[Wanderfound]

@Wanderfound OP updated as per your request.

Thanks, Sirine. Much appreciated; my review of Sirine's performance as challenge host is running A+ so far.

[Wanderfound]

Okay...

I've been trying to take Skathi for a test flight. Unfortunately, there appear to be some serious issues.

The major one is that it appears that the maximum authority values on the control surfaces have been wound down to extremely low values (15 is default, 30 is my standard for rear surfaces):

Because of this, I've been unable to get it off the runway, even with the flaps set to maximum:

And, really, a plane this small shouldn't need flaps to take off at all. Fortunately, there's an easy fix: crank the rear surfaces to 30, and bring the forward ones back up to 15.

Other early impressions: the pre-loaded spacecraft in the cargo bay is cool. It would be nice to have an action group to toggle the RAPIERs separately from the O-10s. Aesthetics...not too bad for a drone plane, but I'd prefer a cockpit, personally. There doesn't seem to be a solid reason not to have one.

Will crank up the control authority and report back later.

--

Also: the only control surfaces set to influence pitch at all were the forward canards. This is...not optimal. Resetting the elevons to affect pitch.

--

Control surfaces appear to deflect in the opposite direction to what is desired. Stripping and replacing.

Edited August 28, 2014 by Wanderfound

[Wanderfound]

Hmmn...replaced the elevons on Skathi, and it was still sending the control surfaces the wrong way. Might be a bug at my end.

Anyone else had a go?

[Wanderfound]

No matter what I do, attempting to pitch up with Skathi makes the elevons aim downwards.

Anyone else want to try?

[Wanderfound]

Flight testing of the Laythe Wing.

First up: this is a very well-built plane. It takes off easily, and is absolutely rock solid once it's in the air. If you can't get this to orbit, the fault is in the pilot, not the plane.

However: there are a few niggles. Firstly, speed; although it has plenty enough grunt to crack Mach 4 and go to orbit, it takes a while to get there.

Of course, this doesn't mean that you can't get it up to serious speed if you want:

Secondly: aesthetics. It looks okay for a mostly stock-parts plane, but the impending stockiness of SP+ has illustrated just how aesthetically weak the stock parts are. The full-width wing works well, but it's essentially an old kludge that was used to overcome the lack of stock-parts lifting bodies; not really needed with SP+ parts. The Laythe Wing is highly functional, but only its Mum would claim that it's pretty.

Overall: a very well built plane, but competent rather than exceptional. A worthy addition to any garage looking for an economical workhorse, but not quite up to elite standards.

Edited August 29, 2014 by Wanderfound

[Master Tao]

@Wanderfound:

First off, thanks for trying Skathi. Glad you liked the Minmus lander I included, even though it does cause some confusion. I'll try to address all of your concerns, but all the issues you've encountered so far can be solved by:

• Reading the flight instructions in the post.
  
• Looking at the navball at launch.
  
• Or, downloading this version with a dummy payload.
  

The major [issue] is that it appears that the maximum authority values on the control surfaces have been wound down to extremely low values (15 is default, 30 is my standard for rear surfaces): a plane this small shouldn't need flaps to take off at all.

The control surfaces were tuned to their current values on the assumption that most people fly with keyboards. Any less, and you won't have necessary control authority; any more, and it will spontaneously disassemble during reentry.

Most planes have flaps because it makes them easier to handle. Flaps are intended to increase lift and drag during takeoff and approach, reducing the takeoff and landing speed. Skathi has wingloading comparable to the Eurofighter Typhoon, so the landing speed without flaps would be dangerously fast. As it stands, the fully-loaded takeoff speed is about 110 m/s (250 mph) and the landing speed is about 55 m/s (125 mph). That's slower than most passenger jets at touchdown.

Will crank up the control authority and report back later. Also: the only control surfaces set to influence pitch at all were the forward canards. This is...not optimal. Resetting the elevons to affect pitch.

One of the major issues spaceplanes face is the high AoA (30°-45°) they must maintain during reentry. The canard control surfaces provide plenty of control authority, especially if you use the independent flap controls (Action Groups 5 and 6). Turning the ailerons into elevons is a Bad Idea^TM: using both sets of control surfaces for pitch causes pitch authority to increase with AoA. That means that during reentry, the plane would flip in response to the small input.

Other early impressions: the pre-loaded spacecraft in the cargo bay is cool. It would be nice to have an action group to toggle the RAPIERs separately from the O-10s.

Aesthetics...not too bad for a drone plane, but I'd prefer a cockpit, personally. There doesn't seem to be a solid reason not to have one.

Mostly fair points. I'll admit that I didn't separate the action groups for the RAPIERs and 0-10s because I don't have enough buttons on my joystick . As far as a cockpit, that would require a total redesign because it would necessarily shift the CoM forward quite a ways.

No matter what I do, attempting to pitch up with Skathi makes the elevons aim downwards. Anyone else want to try?

Read the flight instructions (especially Pre-flight #13), look at the navball, or fly the version with the dummy payload.

[Wanderfound]

I do admit that I didn't read all of the flight instructions. I did have a look at them, but my response was "holy hell, that's long and seems unnecessarily complicated for a fairly simple plane; I'll just take it for a spin and see how it goes".

Will re-test after a good look at your instructions and report back. It deserves to be flown as intended.

I fly by keyboard, BTW, with fine controls off (I dislike the inconsistency in response that the fine controls create). Tap tap tap.

What mod are you using for that cool flight data display?

Edited August 28, 2014 by Wanderfound

[WafflesToo]

I dunno... I've gotten pretty darn good at tap-tap-tapping

Going to try to get a few of these downloaded tonight and start flight testing. I want to make sure to give each of the FAR flying ones their due so I want time to become proficient at flying them before I start squirting out numbers. I'll probably follow Hodo's format, it looked pretty good.

[Master Tao]

I do admit that I didn't read all of the flight instructions. I did have a look at them, but my response was "holy hell, that's long and seems unnecessarily complicated for a fairly simple plane; I'll just take it for a spin and see how it goes".

Will re-test after a good look at your instructions and report back. It deserves to be flown as intended.

I fly by keyboard, BTW, with fine controls off (I dislike the inconsistency in response that the fine controls create). Tap tap tap.

What mod are you using for that cool flight data display?

You can skip most of the instructions, but I added Pre-flight #13 because of the control issues, and the Transsonic instructions are my own solution to controlling with a keyboard. With your experience, I'm confident you'll figure out what happened as soon as you see that note or take a closer look at the navball.

The display mod is DaMichel's Kerbal Flight Data. It has some neat reflective support for FAR and DRE. I've found the dynamic pressure display really helpful for avoiding aerodynamic failures. DaMichel also has an entry here.

Now that I'm home, I may finally have a chance to fly some of these planes.

[Wanderfound]

You can skip most of the instructions, but I added Pre-flight #13 because of the control issues, and the Transsonic instructions are my own solution to controlling with a keyboard. With your experience, I'm confident you'll figure out what happened as soon as you see that note or take a closer look at the navball.

Yup. I did look to make sure that it wasn't upside down, but I didn't consider back to front. Mea culpa.

I'm loving Kerbal Flight Data (just installed today, thanks), but I was actually asking about the black square in bottom right of some of the screenshots. Some sort of specialised landing aid?

Edited August 29, 2014 by Wanderfound

[Wanderfound]

BTW, as the Skathi incident demonstrates, there may be some flight difficulties related to designer's personal preferences as to control authority.

I like a vigorous amount of control; I prefer planes that do exactly what I tell them to, even if I'm telling them to do something crazy. This is worth keeping in mind when testing my designs; use a heavy hand on the Migration and it will kill you. It's very much not a design intended for use as a trainer.

Feel free to wind down the control authority if it gives you trouble; just be sure to keep the front/rear balance in a similar ratio to what's already there. Do give it a shot with the existing settings first, though; just remember that it's more Concorde than Cessna.

As mentioned in the flight notes, there's a degree of roll instability while climbing at low speed that needs to be managed immediately after takeoff, but this disappears entirely once you're up to minimal cruising speed and isn't an issue when landing.

Edited August 29, 2014 by Wanderfound

[Master Tao]

That's kujuman's NavUtilities Horizontal Situation Indicator and Instrument Landing System. It provides a compass, runway localizer, and glideslope indicator. You can even create custom runways in-game.

[Wanderfound]

Alright: take 2 on the Skathi flight test.

When flown by someone who pays attention to the designer's instructions, it takes off very easily:

The flaps are required for low-speed level flight, but that isn't a flaw; it's just the plane performing as intended by the designer.

It has no problem with maintaining a rapid climb rate:

And it certainly isn't slow:

It's nice to see someone using the O-10's for something other than physics demonstrations:

But unfortunately, attempting to use the OMS for circularisation exhausted the RCS supply before completing the burn. Another RCS tank or two stuck in the cargo bay would be a worthwhile addition.

It could also use a bit more in the way of lighting:

Overall, a very nice ship, and certainly in the running for my vote. Not everything is done the way I would have chosen, but that's just a matter of personal preferences rather than anything flawed in the design.

The only real niggles are the lighting, the limited RCS supply and the action group setup, and "niggles" is all that they are. It's an easy to fly, economical, fast and practical way of delivering both crew and cargo to orbit.

This comes from a designer worth watching; I'm sure that there is more quality to be found at this source.

[DaMichel]

Flight testing of the Laythe Wing.

Secondly: aesthetics. ... not really needed with SP+ parts. ...

Thanks for flying the Laythe Wing. But this part is simply not true. The cargo doors are absolutely essential for hiding the VTOL engine which would otherwise generate prohibitive amounts of drag under FAR. The rest is very subjective ...

Overall: a very well built plane, but competent rather than exceptional. A worthy addition to any garage looking for an economical workhorse, but not quite up to elite standards.

I disregard this as unsubstantial propaganda

---

Btw., @all participants: do you know the Kerbin Side mod? http://forum.kerbalspaceprogram.com/threads/82785-0-24-x-Kerbin-Side-v0-34-Now-With-More-Crate It adds additional airports to Kerbin - and other stuff. I just installed it and i think it can increase the enjoyment everyone gets out of this challenge by breaking the routine of always using the same old KSC airport. (Disclaimer: I'm in no way associated with the authors of Kerbin Side)

Edited August 30, 2014 by DaMichel

[Wanderfound]

Thanks for flying the Laythe Wing. But this part is simply not true. The cargo doors are absolutely essential for hiding the VTOL engine which would otherwise generate prohibitive amounts of drag under FAR. The rest is very subjective ...

I don't have any problem with the cargo doors; those are awesome. It's the wing boards directly on top of the fuselage that I think you could probably do without. It's not short of lift or stability, and ditching a wing piece or two should also help with the okay-but-not-spectacular acceleration. Shrinking the rudders somewhat would have similar effects. Keeping the high-wing design is possible, but you may be better off with a mid-mounting.

I'd also consider adding a couple more Vernors on the flanks for roll stability during VTOL operation. It is possible to set them to toggle on and off by action groups, and their fuel consumption is minor so long as you only flick them on when you need them.

Not that there's anything wrong with its current VTOL performance:

...but adding a bit more rapid-response lateral stabilising thrust would make it a lot more tolerant of Kerbalesque sillyness.

Thanks for the diagram and detailed explanatory post, BTW. The small touches like the ladder are particularly nice; that was a pleasant surprise. It's got me thinking about the possibility of making a KSP version of the Fulton Recovery System: http://en.wikipedia.org/wiki/Fulton_surface-to-air_recovery_system

BTW, action group 3 on my version toggles the doors but not the VTOL engines; it might be worth checking the download.

I disregard this as unsubstantial propaganda

Also, folks; the leads me to think that DaMichel gets it, but for anyone else who might not:

I'm giving an honest appraisal of my impressions, but I'm obviously going to be biased towards my own subjective preferences. Everyone is likely to be a bit protective and defensive about their own designs (myself included), but try not to take it too personally if someone criticises your baby.

We're acting as competition judges here; trying to find flaws in the designs is a major part of the deal. We're also doing it as spare-time entertainment, not as a profession; the degree of due diligence in the reviews may not be quite up to what there would be if this was for real.

And, more to the point: we're playing a game. A sandbox game. The only way to lose is to not have fun. Do it right and we all come out ahead.

Anyway: let the best plane win!

Edited August 30, 2014 by Wanderfound

[Wanderfound]

Speaking of checking uploads...I noticed today that a couple of the control surface settings on the Migration weren't quite what I'd intended (been having some troubles lately that have messed up my fine motor control, and I'm misdirecting a lot of clicks). I've updated the file at the download link, so if you downloaded it previously you should replace that with the new version.

[DaMichel]

The competition thing is working as intended. Sirine will be proud. And yes i suppose i get it I also have some critique about your craft.

But first, about the action groups. That is odd. Hodo also had problems. I on the other hand see no AG to toggle the aerospikes on the Kerbodyne Migration. Might be another strange bug. A quick google search got me this http://forum.kerbalspaceprogram.com/threads/78539-Missing-action-groups. I have no mods, that mess with AGs so there is not much i can do.

Moreover about the wing setup. I thought i should go with a proven design much like Ferrams Thunderbolt, i think the name is. This works very well balance wise since it allows me to mount the side tanks right next to the main fuselage. It also makes the wing placement painless since i can shift them forward and backward where i would face problem due to the angled Sp+ parts if they were center mounted.

So i flew the Kerbodyne Migration. I like the name, very fitting. It certainly fulfills the promise that it is a very fast plane. The rapiers actually provide enough power to get into space already. True to the Kerbal way, a set of aerospikes have been added. I wonder though if it wasn't better to replace at least a pair of rapiers with turbo jets. This would presumably give you better atmospheric performance.

Well, you get into space very quickly if you survive. My takeoff experience wasn't very pleasant. The Migration is very unstable indeed. Only between mach 2 and mach 4 it felt really comfortable. Landing, again was a bit hairy since i could not get rid of some side slip. I though it would veer off on the runway and explode but it didn't and behave well after ground contact.

Many of my Sp+ designs are also quite unstable in yaw. Perhaps it is due to the general "flatness" of the Sp+ fuselage parts. Might be worth a try to see how the Migration behaves with the large delta wing pieces as vertical stabilizers.

I see we have different tastes regarding aesthetic. I think the dozen canard surfaces look terrible together. There are no larger all-moving wing pieces in SP+ so it is hard to blame you ... but still ... (i find the forward swept canards the worst offenders).

On last thing, in comparison to the Skathi: The skathi appeared to be much more stable during reentry at high angles of attack. I don't remember it rolling violently as soon as it enters a severe stall like the Migration does.

All in all, i'm not super impressed by it. I think if it just behaved better at low speed it would be nice passenger and possibly transport plane which i could like. This was the old version btw.

Edited August 30, 2014 by DaMichel

[Wanderfound]

(snip vigorous review)

If you've got the time, please give the new upload a shot. The thing that was wrong on the old upload was that several of the forward surfaces were set to affect yaw when they should not have been; this had a dramatically negative impact on stability in all axes. If you've got a version that is tuned as it should be, the only control surfaces affecting yaw will be the rudders. The outermost rear horizontal surfaces are ailerons set for roll only, pretty much everything else is set to work as an elevon.

When working and flown as intended, it should be able to maintain a stable hands-off 20° climb within about twenty seconds of leaving the runway. I think the flight demonstration I provided with my entry show that it has adequate stability when set up as designed. My mention of roll instability just meant that you typically needed to level the wings before setting your trim just after takeoff; once you've done that, it should fly straight and level from then on.

It is intended to be flown with SAS on at all times, and it's not designed to take extreme angles of attack during reentry. Use the spoilers and intakes to enhance drag in the upper atmosphere, get down to ~21,000m as fast as you can without burning up, and hold that altitude until you're down to about Mach 2. The nose should stay within 20° of prograde the whole way, and by the time you're getting heating effects you should be below a 10° angle of attack.

There definitely appears to be something screwy going on with the action groups; the Aerospikes are certainly set to action group one on all of my versions. I never use staging at all on my spaceplanes. I've had missing action group weirdness on every plane I've tested so far, I think.

I suspect industrial espionage.

BTW, the major motivation for the Aerospikes was for use as propulsion in vacuum with higher fuel efficiency than the RAPIERs. Although I love the look and sound of turbojets, I'm starting to move away from them except for medium-altitude craziness. By the time the RAPIERs flick to closed cycle, I'm usually close enough to hypersonic that turbojets have negligible thrust.

[WafflesToo]

Everyone is likely to be a bit protective and defensive about their own designs (myself included), but try not to take it too personally if someone criticises your baby.

I would never take criticism of my baby personally...

(have them put on the wall and shot) -_^

[Hodo]

I would never take criticism of my baby personally...

(have them put on the wall and shot) -_^

I have considered throwing a design in even though I have said I would not. But I will say I have been overall impressed by the innovative designs and original concepts that have come out in this challenge.