Criticize my Spaceplane, if you please

[G'th]

So I'm finally on the verge of a full SSTO spaceplane that's basically perfect as far as I can tell. It gets to orbit without issues (without cargo, 1.5km/s of dV left at orbital insertion) and while I'm still working out exactly how I want to deorbit (I keep overshooting KSP or coming down too fast and exploding) it normally makes it through alright. As I designed it, it stays extremely stable during the ascent, while during reentry it becomes a super-maneuverable machine (i'm talking pulling out of a 65 degree dive during my last reentry test.)

But now, I want to see if there's anything I can do that can make it even better! Now the obvious thing is going to be the massive amount of cargo space (Note: I edited the cargo bays to carry fuel internally. This was to save me a headache and because it makes sense. However, I do have a smaller cargo/passenger version in the works that can use a non-fueled b9 cargo bay and still have most of the same performance) that I might not always use, but I'd rather have it, mostly because my docking and utilities structure takes up half of a 6m cargo bay as it is so I'd rather have some empty space rather than cramped conditions.

Here's some pictures:

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Now the main things I'm looking for as far as improvements go is are to do with the wings and control surfaces. Shape, size, the placement and number of my intakes, my elevon and rudder settings, etc etc. While what I have certainly works, any tweaks here and there that might help would be appreciated.

I also have a side question regarding the b9 S2 cockpit and RPM. Isn't it supposed to have more than one RPM screen? Mine only has one and I'm almost certain it shouldn't. (considering there's the old b9 screens all over the place) This is a fresh install from a couple days ago, so nothing should be out of date.

[Hodo]

Ok this is what I see with that craft. First I am not familure with the engines you are using so I can't say anything about your thrust to weight ratio. But as for the CoL and CoM, I see you have your CoM when wet (fully fueled) way ahead of your CoL. You will have some serrious pitch issues when you hit mach 3+ the craft will become extremely nose heavy and not much pitch authority at those speeds. If you are using some kind of fuel balancer program you could shift the fuel load towards the rear of the craft and keep it a bit more balanced.

Your dry CoM location is perfect for hypersonic flight because your CoL will actually move back at supersonic and hypersonic speeds in FAR .

[Wanderfound]

First up; congrats on building a plane that you like. Most folks find that very hard.

The following is probably going to sound harsher than it's meant; I wouldn't be posting this if you hadn't specifically asked for critique. Just at a first glance:

* You have more intakes than you need. Also, from a realism POV, the placement means that they would lose their airflow as soon as the wing stalls.

* You have more sets of landing gear than you need.

* You have a large displacement between CoM and dCoM. Try to keep it below 1m if you can. Spread your fuel load laterally and keep it close to CoM.

* All of your control surfaces are rear-mounted and conventional (as opposed to all-moving). This may give you pitch authority problems at supersonic speeds.

* Set your rudders to affect yaw and nothing else. Set your elevons to not affect yaw. Tune max control to personal taste; one person's "responsive" is another person's "unflyably oversensitive".

* Are you keeping aerodynamic failures turned on? Your wings appear to be unreinforced; I'd expect them to be easily torn off during over-vigorous manoeuvring.

* Do you have an abort system (e.g. decoupler behind cockpit, parachutes on the cockpit, both triggered by the abort action group) for when things go wrong?

* Do you have any lights aimed at the docking port so you can see what you're doing during docking?

* Do you have any downwards-facing solar panels? Single-direction solar is a recipe for disaster on long space flights.

* Have you checked your RCS balancing?

* Have you unlocked the steering on your front gear?

[G'th]

Ok this is what I see with that craft. First I am not familure with the engines you are using so I can't say anything about your thrust to weight ratio. But as for the CoL and CoM, I see you have your CoM when wet (fully fueled) way ahead of your CoL. You will have some serrious pitch issues when you hit mach 3+ the craft will become extremely nose heavy and not much pitch authority at those speeds. If you are using some kind of fuel balancer program you could shift the fuel load towards the rear of the craft and keep it a bit more balanced.

Your dry CoM location is perfect for hypersonic flight because your CoL will actually move back at supersonic and hypersonic speeds in FAR .

Actually this fits my ascent profile. By the time I hit mach 3, I take my hands of the controls for the most part. When I need to pitch, its only just to pull my velocity vector above the horizon, in which case I don't need much authority. The engines are the non-Karbonite fueled jet engines from Karbonite. They're more powerful that the stock turbojets

Wanderfounds post

No worries, I like criticism when its constructive!

Intakes - I could definitely go with less. I just remember reading somewhere that 3 intakes per engine was recommended so thats what I went with.

The gear was kinda-sorta necessary. Without them, the plane does not like to stay straight going down the runway. I could probably find a sweet spot that stops this, but considering the mass isn't all that significant I'm not all that worried. It also supports self-taxiing (the motors on the b9 gear are awesome) so I don't have to wait 5 minutes to get it on and off the runway. I do have the steering set up for the front gear.

I do have aerodynamic failures off at the moment, but this was because I had not yet decided on a wing configuration that I liked and supported the craft, so I didn't want to waste time reinforcing a design if I wasn't going to keep it. I do plan to turn them back on and then brace the entire craft once the design is done.

An abort system would be a good idea, i'll have to look into that. I can dock in the dark, so lights aren't all that necessary. The solar panels are more just there for aesthetic purposes, as I use two RTG's as the main power source.

[O-Doc]

I'm assuming the fuel is jammed between the cargo bay and the engine block. It's better to put your fuel down the sides of your cargo bay with the same CoM as your cargo. That will give you complete payload flexibility.

I would push your rear gear assembly back and go with a canard on the front. More flexible take-off, landing and ascent profile with less tail strike danger. I can see you will takeoff by just powering down the runway but, you have to consider landings too.

Also, I think your weight bearing of the rear gears on the wing is dangerous. Put an I-beam out from the fuselage centerline(level with the wing), mount the gears on that and strut.

I personally prefer to have my CoM/CoL about 2/3 the way down the body of the plane. You get more of the lawn dart effect. I find a plane with CoM/CoL half way very susceptible to flipping on re-entry.

[Wanderfound]

I would push your rear gear assembly back and go with a canard on the front. More flexible take-off, landing and ascent profile with less tail strike danger. I can see you will takeoff by just powering down the runway but, you have to consider landings too.

Also, I think your weight bearing of the rear gears on the wing is dangerous. Put an I-beam out from the fuselage centerline(level with the wing), mount the gears on that and strut.

The wing mounted gear is why he's having steering issues. As the plane accelerates down the runway, the wing flexes. As the wing flexes, the steering geometry changes. Fuselage mounting is always preferable if you can.

If they're on the wings to make the nose higher, consider mounting partway up the sides of the fuselage and rotating until they point straight down. Angled gear is as troublesome as wing gear, for similar reasons (suspension flex instead of wing flex, but the effect is the same).

I'd second the canard recommendation; as well as easing takeoff, it will help in pulling the nose up at extreme speeds and altitudes.

You may wish to set some of your control surfaces as spoilers. As well as helping you stop after landing, you can use them to increase drag in the early stages of reentry.

If you want some examples of things that work, check out my design thread: http://forum.kerbalspaceprogram.com/threads/90747-Kerbodyne-SSTO-Division-Omnibus-Thread