Rescaled shuttle aerodynamics (FAR)

[NFunky]

Hey guys, you're a bunch of smart people, maybe you can tell me if this seems right.  Overview is, I'm working on a small mod that rescales all parts to 2x, for use with RF and RSS (not RO).  This allows me to pretty much build stock-ish craft that have reasonable performance in RF and RSS.

So, got a question about FAR, aerodynamics and rescaling.  Does anyone know if I change the rescaleFactor, if that will automatically inform FAR we are dealing with 4x larger surface areas?

I have been trying to build a Mk3 Space Shuttle, and am running into some interesting problems.  I basically have to balance it to where it is slightly unstable during reentry (CoM too far back) in order to make it maneuverable enough to attempt a landing.  Otherwise, as soon as I'm subsonic, it's lawn dart time.  I seem to remember that the CoL moves toward the back when supersonic, but it almost seems to be the reverse case for my shuttle.

Finally, once I've gone below 5km, I have to maintain a very steep dive, and pull out very hard at the last second in order to have the lift to land.  I know this is pretty realistic, but can someone give me the actual numbers for shuttle final approach?  I have to go in a nearly supersonic speed, and I have to start the flare at above 2km to make it in time.  This is what got me thinking something was really wrong with my aero model.  I have to be within seconds of the correct flare time, or I nose dive, or loose too much energy and slam down on my belly.

Any help would be very welcome!

[NFunky]

Just for those who are curious, I did discover a partial answer to my first question.  It appears that FAR has a config file specifying wing and control surface lifting area, in the FerramAerospaceResearch.cfg file.

For modules FARWingAerodynamicModel and FARControllableSurface, there are two values.  "MAC", the Mean Aerodynamic Chord, is basically the leading-to-trailing-edge width.  And "B_2" which is the root-to-tip width.  Not quite sure if there is a value for wing thickness, but I couldn't find anything obvious.

HOWEVER, I'm still very curious about the real shuttle's glide slope and landing flare.  Is anyone playing with a real shuttle model in FAR and having a similar experience to me?

[capi3101]

I fly FAR a lot, and I use Procedural Wings for all of my planes using a set of parameters that approximates the same dimensions/shapes of the Space Shuttle wings (it's not 100% accurate since you can't do oblate curves, but it's close enough for jazz). Usually I start re-entry opposite KSC, and keep the nose around 40-50 degrees elevation until I don't have enough pitch authority to hold that anymore. Usually gets the speed down pretty effectively. At landing, I'm usually on a 3-5 degree glide slope, like a normal aircraft.

Can I see a screenshot of your shuttle? Just curious what it looks like. Add your CoM and CoL balls at landing if possible.

If it's a bonafide Shuttle replica, you're dealing with a tailless delta design, is that correct? In that case, the best advice I can give you is to bump up the pitch authority on your elevon controls to maximum. The other thing I'm curious about is your wing area and mass at landing (your wing loading). From the behavior you're describing it sounds like it might be a tad on the high side. I'll know more when I see your design.

Are you playing with any other mods?

 

Sorry that I'm not answering your question directly; I don't know the Shuttle numbers off the top of my head.