Making a stable SSTO using NEAR+DRE

[colin_in_space]

Hello all,

My space-planes suck. I am not so sure what I am doing wrong but I jsut can't seem to get the hang of them.

I am launching a mega Duna mission. Included will be a Duna capable SSTO to do aerial survey missions from Fine Print. I do not need a highly maneuverable aircraft, I want a nice steady flier.

I tried a few designs, and at least in Kerbin they all are very difficult to control. Firstly, none of them get off the ground before the end of the runway. Then they tend to pitch up and down like crazy and start to roll. I got one up to about 25K and it jsut spun out.

Since i want these for Duna they use rockets only (no air intakes). The wackiest part if they are refuelible on the ground due to a karbonite distiller and drill mounted at the back (see pic). This is the critical part for the design, able to land on Duna then do multiple aerial surveys

http://i.imgur.com/ega6DRM.png

This design in a bit weird because it is based around an orange tank. I have also tried MK2 designs, which just disintegrate as soon as they get off the ground mostly, or are INCREDIBLY hard to control. I mounted the engins out on the wings because i heard this was more stable, and stability is key for me.

I would really apprecioiate any help on how to get my SSTOs off the ground and flying steady and true.

[Alshain]

Ok, when you say "my planes suck" what experience with NEAR do you have so far? Have you gotten a 1.25m plane to orbit? Really you should drop DRE if your new to FAR/NEAR until you get more experience. If you are new to NEAR as well, you need to start with 1.25m planes with the only goal is getting to orbit and back to the runway. Once you master that, then you can expand from there.

EDIT: Really I may have gone too far with that suggestion too, you might design a simple atmospheric craft and learn to land first. Just take off, come around, land. Rinse and repeat till you can do it flawlessly.

Here is a guide that can help get you there. Pay especially close attention to the control surface assignment. Don't leave them all assigned to all the control types. (those settings are in the control surface tweakable menu in the SPH)

Trying to fly a Rockomax Jumbo to Duna and not having a lot of experience with NEAR is a bit of jumping in head first.

Take a look at the exchange forum. The second link in my signature is all NEAR planes, toy with those, see how I did it and learn from them.

One thing the guide doesn't entirely cover is Flaps and Spoilers because the guide is really for stock (even though the principles are the same). Flaps are used to allow the plane to fly at a slower speed, ideal for landing. If you plane falls out the of the sky at less that 150m/s, use flaps and deploy them. Spoilers create drag and slow the plane. They can be used after landing to slow on the runway, and with careful planning they can be used as air brakes too (the Harrier in my exchange post has an example of this).

Once you have built a plane based on these criteria, bring it back here and let us see. We can then help you tweak it.

Edited December 1, 2014 by Alshain

[colin_in_space]

Yeah, I had hoped for a smaller plane originally actually. I ended up with the Jumbo because it was the only thing I could get up and stable.

the plain itself doesn't need to reach duna, it will dock with my Duna mothership. I jsut need it to fly around in Duna without crashing : )

Thanks a lot for thre guide. I already see my first big issue: I thought the COL was supposed to be in FRONT of the SoM, not behind it. So that probably helps explain some of my stability issues. But yeah, I will start off with a few simple 1.25 designs and see how that goes. I would actually prefer an MK2 profile than the lousy jumbomax.

[Alshain]

Also remember, aerodynamics matter. You have a lot of wind breaks in that plane you posted. Make sure you use nose cones and keep flat forward surfaces to a minimum. In NEAR/FAR that matters, you can still fly but it won't be very fuel efficient.

[Vaporo]

All right, I think that you need:

1. More of a delta wing rather than a straight wing. (At least, in FAR you would. Not sure about NEAR)

2. Move your wings back a bit.

3. Move your rearmost landing gear forward (just behind the center of mass).

4. Add a bigger tail with bigger control surfaces.

5. If possible, try to make your plane bit more streamlined. It looks a bit "fat" to me.

6. Nosecones on those external tanks.

Generally speaking, your planes will work in FAR/NEAR if you try to make them look like real planes.

Edited December 2, 2014 by Vaporo

[Hodo]

Here is one of my old designs, this is the basics for a working SSTO in FAR/NEAR and DRE.

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You can copy it with the new parts but the basics are still the same.

As for flying it FAR/NEAR is different then stock, you don't fly it like a rocket with wings and hope for orbit, in FAR or NEAR you actually have to fly it like a plane using its lift to get out of the thicker lower atmosphere and above 12km alt then bring your AoA to 10-12deg above the horizon and accelerate to mach 4-5 then burn your way to orbit after you hit 25km and over Mach 4.5. At that point it shouldn't be much more than a 30sec burn to get to space and at most a 10-20second burn to achieve orbit.

[DaMichel]

Also remember, aerodynamics matter. You have a lot of wind breaks in that plane you posted. Make sure you use nose cones and keep flat forward surfaces to a minimum. In NEAR/FAR that matters, you can still fly but it won't be very fuel efficient.

Yes, this also applies to the docking port on top. IIRC FAR applies lots of drag even if it is just a flat plate essentially. I'd use a space plane mod with a large cargo bay and hide the port in there.

Then i think your plane needs much more wing area because landing on Duna is quite difficult and more wing area lets you fly more slowly. You should be able to fly with 30 m/s or so on Kerbin to have a chance of landing on Duna. There is plenty of inspiration for you in the "Flying on Duna Challenge" Thread (click badge in my sig).

I'd also consider adding VTOL engines. There are two ways to do it. Either hidden in a cargo bay (see my Jool mission log). Or using Infernal Robotics rotating mounts for a tilt engine design.

Edited December 2, 2014 by DaMichel

[Alshain]

I'd also consider adding VTOL engines. There are two ways to do it. Either hidden in a cargo bay (see my Jool mission log). Or using Infernal Robotics rotating mounts for a tilt engine design.

Whoa, back the cart up. He's a beginner... if big planes are jumping in head first VTOL is jumping in head first into an empty pool.

[DaMichel]

Well fair enough i guess. On the other hand, SSTO'ing from Kerbin and landing on Duna isn't exactly for beginners in the first place

Actually, if it doesn't have to be a plane, maybe something more like a rocket would work better. The vehicle would be designed to take off and land vertically. Isn't this more fuel optimal anyways because he isn't using any jet engines?! The atmosphere on Duna is pretty thin, so a couple of vernor engines and SAS torque wheels could take care of compensating for aerodynamic forces during the descent. The vehicle should be designed to be stable in forward flight in order to launch from Kerbin w/o problem.

Edited December 2, 2014 by DaMichel

[colin_in_space]

Thanks for the replies guys. I manages a decent spaceplan . With 1.25 m parts which still had the posterior tail karbonite drill. The plane itseft has docked with a mother ship which will carry it to duna orbit. I have a number of airial survey missions for this plane.

I will try to post a PIC tomorrow. I plan to us RCS to help stabalize and break for landing. Earlier versions also had rear mounted drogue shoots but they didn't fit in the final design.

[Hodo]

I will try to post a PIC tomorrow. I plan to us RCS to help stabalize and break for landing. Earlier versions also had rear mounted drogue shoots but they didn't fit in the final design.

This is a quote of quotes.

"Well we finalized the design, it should work with all of the mission needed equipment but we removed the drag chutes so it can come in under budget."

[Alshain]

ROFL. It does sound funny, but to be honest, in the game you don't need drag chutes really. They look cool, and do provide a little steering stability if your landing really fast.... but if your using flaps and spoilers properly, they are mostly cosmetic. If you do add them, make sure you are using RealChute for actual drag chutes (be sure to configure them to be drag chutes). Using stock chutes in place of drag chutes is going to cause more issues that it solves.