B9 Cargo ssto's

[Secuas]

I've made countless designs to make a decent cargo SSTO's using B9 parts but they all failed miserably (you dont want to see what I've tried). I don't use FAR/NEAR and have no intention to. All I need is a medium not like humongous large like the stock Stapledon sized SSTO's able to carry 2.5 meter payloads. Maybe someone here has a great design or some great ideas.

Thanks in advance!

Edited November 19, 2014 by Kaname

[Voculus]

This guy will carry 40 tons into orbit, but only with FAR. You're going to find that lofting 2.5m-sized cargoes into orbit with stock aerodynamics to be a tedious task at best. Nevertheless, hope this provides some inspiration!

[Secuas]

It certainly did , I always tend to put the winglets up from and the wings in the back. Didn't work out too well.

Thanks.

[Alshain]

It certainly did , I always tend to put the winglets up from and the wings in the back. Didn't work out too well.

Thanks.

For the simplest design you want to have the wings trailing edge close to the center of mass (for optimal roll) with independent pitch controls at the rear, all while maintaining the CoM/CoL relationship. That is what he has in that picture and if you look at a common airliner, it's the same. Don't forget to assign your control surfaces. This is not the only way, but it's very common, which makes it one of the better ways.

The design principles between Stock and FAR are really the same, it's just the center of lift appear in different places which is why the planes are incompatible (and in stock you can build silliness, which I'm assuming is not what you want) ((And in far you have a few more options, Flaps, Spoilers, etc)). The best thing you can do is look at real planes.

Feel free to take a look at my exchange thread for inspiration if you like, I've explored many different design ideas, but they are also for Ferram's aerodynamics.

Edited November 18, 2014 by Alshain

[Secuas]

Well, I'm not quite sure what you mean with assign control surfaces. I mean i have gotten planes in to orbit and beyond before but never heard of assigning control surfaces I'd like to know more about this.

[Alshain]

If you right click a control surface you can assign it's function. Pitch, Roll, and Yaw.

Ideally, pitch should act like a force on a lever where the center of mass is the fulcrum. So in the plane above, the rear winglets are your pitch (aka Elevators).

Roll (Ailerons) are best placed around the center of mass (front to back) and as far away from the center of mass on the wing as you can get, but there are exceptions. Roll is more forgiving than pitch and yaw about where it is placed so often in jets where the wing sweeps from front to back the roll and pitch can be combined (Elevons).

Finally, Yaw (Rudder) is usually placed on the back of the vertical stabilizer. Yaw is not even necessary for flight at all but it can help keep your nose where you want it while performing a turn maneuver. Turning using yaw alone should be avoided, it's possible, but not ideal.

FAR/NEAR has some other options, but that's it for stock. Here is a picture with the items identified (note the inner wing surfaces are flaps, which help stay in the air at lower speeds for landing, you don't have those in stock)

Edited November 18, 2014 by Alshain

[Secuas]

I guess what you are saying is toggle some of take for example: the elevators turn their yaw off since they can't yaw anyway? Because this thing just won't take off.

http://imgur.com/a/QTKja#0

I mean I think it's too slow because even with 3 giant sabre's it's just close to about 105.5 m/s and with 2 Sabre's 73 m/s. So I am still wondering how Voculus's can with only 2 of them and still have 40 ton cargo?

(My native language isn't english, so I may have not understood what you tried to tell me) My aplogies. Your help is really being apriciated though.

Edited November 18, 2014 by Kaname

[Secuas]

Is my problem really just speed? because I got this CoL and CoM figured out a long time ago.

[Alshain]

I guess what you are saying is toggle some of take for example: the elevators turn their yaw off since they can't yaw anyway? Because this thing just won't take off.

http://imgur.com/a/QTKja#0

It can yaw, and it will when you least expect it, usually causing the plane to become unstable. Turn them off to prevent the controls from creating forces where you don't want them, same for pitch and roll, turn off the others.

I mean I think it's too slow because even with 3 giant sabre's it's just close to about 105.5 m/s and with 2 Sabre's 73 m/s. So I am still wondering how Voculus's can with only 2 of them and still have 40 ton cargo?

(My native language isn't english, so I may have not understood what you tried to tell me) My aplogies. Your help is really being apriciated though.

You have more than enough engine there. Pretty sure you have enough lift as well, I can't see the wheels, are they in the proper location? They should be just slightly behind the center of mass.

[Secuas]

I uploaded a picture of the wheels to the same album. http://imgur.com/a/QTKja#0 I think 2 Giant Sabre's is enough but the speed wont rise above 75 m/s or so.

[Alshain]

I uploaded a picture of the wheels to the same album. http://imgur.com/a/QTKja#0 I think 2 Giant Sabre's is enough but the speed wont rise above 75 m/s or so.

If the speed isn't getting above 75m/s you do have a speed issue, but I can promise you the wheels are a problem. Remeber the picture of the lever above? Well in this case your wheels are the fulcrum, you have to pivot on them, but they are so far back that when the plane tries to pivot, it just pushes the back wheels into the ground and has no way to lift.

Try taking the back wheels off entirely and move the ones in front of them back just a very little bit. As a guideline, make it so the gear bay on those B9 wheels is right in line with the center of mass ball (the wheels themselves will be just behind it). Now, because you have a long tail you need to very gently pull up or you may have a tail strike, so be careful.

[Voculus]

It's possible that the elevators in the rear are too close to your wing-mounted engines. They may be blocking all of their thrust. You can remove the elevators completely, and just do a test run on the runway. If you find that it's faster, you'll know that's the problem, and you can solve it by placing the elevators higher up.

[Alshain]

It's possible that the elevators in the rear are too close to your wing-mounted engines. They may be blocking all of their thrust. You can remove the elevators completely, and just do a test run on the runway. If you find that it's faster, you'll know that's the problem, and you can solve it by placing the elevators higher up.

Good catch, I didn't even notice that. Now that you mention it your absolutely right. Kaname, try a Cruciform Tail to solve that problem.

[Secuas]

Thanks both of you! I will definitly get right on it tomorrow.

[Secuas]

The trust issue was indeed the winglet on the back. I'd never thought that would be a problem i still haven't got the wheel figured out and it doesnt have much lift either, I threw some pictures in the album.

How can i further increase it's lift?

[Secuas]

This stupid plane is giving me headaches I would like to continue having fun in KSP wich I am not having right now. To my opinion the CoL and CoM are perfect wheels are good. for some reason the trust is way too low again after trying the cruciform winglets as for as I know it's impossible to fly this.

See for yourself. I'm giving up. (On ever getting 2.5 meter payloads in space by plane.)

Download link: http://www.speedyshare.com/ufvfF/VCL-01-Turtle.craft

Edited November 19, 2014 by Kaname

[Voculus]

Kaname, you're still using stock aerodynamics, right? I downloaded your craft, and will try to do some troubleshooting.

[Secuas]

Still using stock aerodynamics? Sounds like FAR/NEAR is the future . I might use them later but thanks for your help it's really being apriciated. Let's see what you can find.

[Voculus]

I tried to fly it without FAR, but apparently I have other mods dependent on it, and the game wouldn't start, so my testing may or may not be useful. At any rate, there were some issues which can be fixed to make flying it more pleasant. To avoid being too wordy, let me throw a pic at you:

I'm just going to make a bit of a list here, in no particular order.

The first thing I did was remove all of the fuel from the fuselage, except for the MonoPro. Using just the fuel in the wing tanks, I was able to get into an 80 x 80 orbit with over 2000 dV left over, with no payload in the cargobay.

The tanks were configured to hold a huge excess of liquid fuel, which would take you hours and hours of atmospheric flying to burn through. If you want to travel far, it's better to set them for an LFO mix, and refuel in orbit, if possible.

Just behind the cockpit, were five separate fuselage tanks, which flexed like a slinky during some parts of the flight.

Building wings from many smaller parts is a bit of an art, and I think you'll find it easier to mount them all to the fuselage. From there, you can mount engines and tanks to the trailing edge of the wings. Different parts of the wings were flexing a great deal during flight, and also made tanking off and landing difficult, due to the wheel wobble.

Again, insomuch as FAR is concerned, you had more than enough lift, and could easily reduce the overall wing area, to make building easier, and to reduce weight. FAR also greatly increases wing strength and weight, by default, so I set the weight/strength values of all wing sections and control surfaces to 30%, which reduced the ships overall weight from 212 tons, to 106.

All of the control surfaces were set to control roll, pitch, and yaw, simultaneously, which stock KSP doesn't mind, but causes grief under a more realistic flight model. Ailerons were set to roll, elevators to pitch, and rudder to yaw.

Instead of slinging my slack jaw even further, let me throw one more "inspirational" pic at ya, to illustrate some of the design mumbo jumbo I was going on about:

It's certainly not perfect, and FAR gives me a bunch of guff about sideslip, but whatever! It's capable enough, and I've only crashed it a few times.

With all that said, if you do decide to give FAR a whirl, you'll find some pleasing and also some jarring differences than what you're used to. Mashing down the S key, or pulling full back on the stick at high speeds = dead bird. Smooth and steady = carry 20, 50, or many more tons than that into orbit with some awesome spaceplanes. I recently started a career game, and went into full-on spaceplane mode as soon as I could. If you spend a lot of time with winged craft, I think you'll really enjoy using it. Don't let all of the graphs and numbers throw you off. It's daunting at first, but you'll find that if you pay attention to your CoM/CoL relationships, and more or less build your planes in a sensible manner, you don't even need to worry about the numbers.

They also don't have to all look like jumbo jets. Big delta wings in the rear with canards up front are also plenty viable and a lot of fun!

Anyway, I hope that was helpful. If there's anything else I can help with, just ask!

PS: Planes that cruise fast under FAR also don't slow down for anything, so the speed brakes included with B9 are essential to - well - every plane you build! Realchutes is another fantastic mod to help slow down on the runway, as well.

Edited November 19, 2014 by Voculus

[Secuas]

Thanks for the explanation. One little question. Whats the actual diffrence between FAR and NEAR because I've only used NEAR before and mainly deleted it because it messed up my gravity turn with VAB assemblies. (That's just me... I sometimes judge too fast.)

Thanks again Sensei spaceplane master.

[Voculus]

I haven't used NEAR, but it's a simplified version of FAR that dispenses with the graphs and numbers, and also removes aerodynamic failures, I believe. You can turn those off in FAR, too. Based on my reading, if you want to say goodbye to the stock souposphere, I'd go all in with FAR. It's true that it'll mess with your rocket mojo, (in a realistic way) particularly if they're short, but again, the pay off is a more realistic flying experience, and about 1000 less dV required to get into orbit, thanks to the much more accurately-modeled air.

[Secuas]

Alright, I just want to get better on how to spaceplane. I will try FAR out soon. Thanks again.

[Einarr]

I'm going to assume you remembered to turn the brakes off, right? Also all intakes open, all engines running, etc?

[Tankbuster32]

Also, NEAR doesn't have mach effects, which makes wing design way too easy

[Secuas]

I have decided to play with NEAR since i prefer it over FAR i have gotten my 2.5 payloads into 200x200 orbit and succesfully rendezvoused (Barely). 2 questions remain however. 1: Can I have some instructions on how to fly it more efficient? 2: How can I reduce the wobbling during flight?

Thanks in adfvance.

Edited November 21, 2014 by Kaname