Official FAR Craft Repository

[Gordon Fecyk]

2 minutes ago, Nixod321 said:

Your aircraft seems extremely heavy: you must have a crazy high wingloading.

Most of that is fuel. As I have an excess of fuel on landing, I might be able to ditch the set of FL-T400s, or trade them for FL-T200s. Having the excess could prove handy in space. I tried LV-Ns instead of Aerospikes, but I can't get the thrust I want. I've crammed fuel where I could without compromising the cargo space. "Fat-Star" seems appropriate; this and other FAR space planes I've flown have been little more than horizontal rockets or flying fuel tanks with lousy TWR.

Each wing is three Big-S wings and two Big-S strakes, and lots of autostrut abuse. If I move those any further forward I'll block the hatches on the cockpit. I could attempt to graft more wings to the assembly; I'm trying to keep this stock, avoiding TweakScale and Procedural Wings. There has to be a limit though; too much wing would mean too much drag in the upper atmosphere.

Having the centre of mass more forward also seems to mess with re-entry, where reaction wheels then have to work harder and drain more electric charge. Adding more batteries does let me adjust the CoM though. "Lawn dart" behaviour is something I'd rather avoid; the thing regularly crashes into the water on take-off with that.

I could have two Big-S tail planes; that could work like it did with the LTS series.

[Nixod321]

1 minute ago, Gordon Fecyk said:

Most of that is fuel.

...

I could have two Big-S tail planes; that could work like it did with the LTS series.

You don't need to increase your wingspan, just the winglength; I should have been more clear. I should really of suggested long, highly swept wings, which should give you more lift without the extra drag. You'll also get lower stall speeds than with a delta.

Drop tanks could be an idea. It won't be an SSTO, but it could be a better engineering solution.

You may have to compromise on wether your design is better at high or low AoA, and wether it has a higher or lower top speed in regards to the position of the center of mass. Those categories are not mutually exclusive, but it can be very difficult to get the best of both worlds. 

 

 

[capi3101]

13 hours ago, Gordon Fecyk said:

Help wanted with "Fat-Star McTater-Tot"

I'm having trouble with this craft, named after Keptin's Basic Aircraft Design post:

Craft file here (15 KB ZIP). Saved with KSP 1.3.0, but you can edit the version number to 1.2.2 and load it there. Tested with Ferram Aerospace "Lewis" edition.

Power Plant: 8 x JX-4 Whiplash, 4 x T-1 Aerospike. Capacity: 36 tonnes cargo at least, four crew. Probe core provided for un-crewed deliveries. I have flight instructions in the craft description. I can return an empty craft from low Kerbin orbit with about 2400 LF and 1600 OX remaining, so I imagine it has a fair bit of delta-v from LKO.

I'm running into these problems:

• I can't make flaps work like flaps with the elevons and canards attached. It does take off from the edge of the runway.
• Craft shimmies left-to-right a bit depending on speed and altitude. More reaction wheels help, but that's a strain on electric charge.
• Pretty high empty stall speed: 150 m/s, mostly from lack of flaps. Drogues are a must for safe landing.
• It does fly if you pay attention, but a significant distraction may be disastrous. 

I've thought about adding more tail planes, but they don't attach well to these Big-S wings. Any suggestions?

I agree with the advice that @Nixod321 has given you, particularly in regards to your wing loading. For a 28 meter long aircraft with a mass of 178 tonnes, a total wing area of 356 square meters will give you wing loading of .5 tonnes per square meter, which would be comparable to a Concorde (.5 is usually what I shoot for with my spaceplane designs). Add your 36 tonnes of cargo and that becomes 0.6, a bit on the high end but still acceptable. If you want .5 with your cargo, you'll need 428 square meters of wing area.

I also agree with the notion of twin tails - my calculator for the same mass (178 tonnes) and length suggests a vertical stabilizer with a span of 6.78 meters (assuming a 3.5 meter root and 1.75 meter tip) is what you need, which is definitely out of the range of any of the stock parts...at least, any single stock part. 

I might suggest Procedural Wings if you find yourself having difficulty with the stock wing parts.

Edited August 7, 2017 by capi3101
dropping advice about the engines...

[Gordon Fecyk]

@Nixod321 and @capi3101 Sorry for confusing one thing: That displayed mass includes the 36 t cargo; you can barely see the orange tank in the image. An empty craft (Ok loaded with fuel) would be 142 t.

But given eight Big-S wings and four Big-S strakes plus control surfaces, that's about 140 m² horizontal wing surface. So I'd have to double this and more, somehow.

Capi, you might have been onto something mentioning the engines. I can get an empty craft to space on half of the engines, but had a major problem with asymmetrical thrust once in space. I could cut four of the Whiplashes and two of the Aerospikes, and either edge-mount the two Aerospikes or clip all six engine assemblies into the wings. That would also eliminate the accompanying tanks and air intakes, reducing the mass considerably. I wouldn't lose style points for clipping fuel tanks into those wings, would I?

[capi3101]

1 hour ago, Gordon Fecyk said:

@Nixod321 and @capi3101 Sorry for confusing one thing: That displayed mass includes the 36 t cargo; you can barely see the orange tank in the image. An empty craft (Ok loaded with fuel) would be 142 t.

But given eight Big-S wings and four Big-S strakes plus control surfaces, that's about 140 m² horizontal wing surface. So I'd have to double this and more, somehow.

Capi, you might have been onto something mentioning the engines. I can get an empty craft to space on half of the engines, but had a major problem with asymmetrical thrust once in space. I could cut four of the Whiplashes and two of the Aerospikes, and either edge-mount the two Aerospikes or clip all six engine assemblies into the wings. That would also eliminate the accompanying tanks and air intakes, reducing the mass considerably. I wouldn't lose style points for clipping fuel tanks into those wings, would I?

178 tonnes and 140 square meters of wing area - that's a wing loading of 1.27. Definitely explains a number of things, not the least of which is your current need for drogues. Are your control issues at low altitudes and relatively low speeds?

My calculator says you wouldn't want to go to space with a loaded craft on less than six Whiplashes; I'd guesstimate that six-and-six would probably offer you the best results. As for clipping/style points, that's really up to you.

[Gordon Fecyk]

1 minute ago, capi3101 said:

Are your control issues at low altitudes and relatively low speeds?

Moreso at higher altitudes and higher speeds. The craft will drift to the right, but I'm sure I built everything with lateral symmetry. That might get fixed after adding more tail planes, like it did when I converted Thrimm's LTS planes to FAR.

I can deal with drogues. A 150 m/s stall is tame compared to the Mk2 missiles I've landed at 200 m/s or so. Drogues seem overpowered now, compared to FAR Lanchester on KSP 1.1. Still, I might be able to build longer wings that get swept back further.

The static stability assessment in FAR tells me I'm wrong in at least two places at low speeds and altitudes. I'm usually better than that. If I can hit 175 m/s on take-off though, it seems OK.

Where's the wing surface calculator you mentioned? Or is there a formula, spreadsheet, or something I can look at? Thrimm had a basic engine calculator, but that was for stock aero and not FAR.

[capi3101]

29 minutes ago, Gordon Fecyk said:

Moreso at higher altitudes and higher speeds. The craft will drift to the right, but I'm sure I built everything with lateral symmetry. That might get fixed after adding more tail planes, like it did when I converted Thrimm's LTS planes to FAR.

The static stability assessment in FAR tells me I'm wrong in at least two places at low speeds and altitudes. I'm usually better than that. If I can hit 175 m/s on take-off though, it seems OK.

Where's the wing surface calculator you mentioned? Or is there a formula, spreadsheet, or something I can look at? Thrimm had a basic engine calculator, but that was for stock aero and not FAR.

Okay...sounds like you might have a case of dynamic lateral instability going on. About what altitude/speed does the drifting develop? And what do your static parameters look like on the surface?

 

My "calculator" is just an Excel spreadsheet I use that has a bunch of different formulas I've come up with for aircraft design over the last several versions of KSP/FAR (since I made the switch with KSP v0.9). Determining the desired wing loading is one of the early steps, though, and you can use just a regular calculator for it. My spaceplane design process begins by determining the desired capabilities of my craft (for example, an automated tanker is going to want to have the fuel payload, the probe core and all its goodies, the docking/port and all its goodies, all all the miscellaneous accouterments like electrical power and so on). I'll then put together a basic fuselage that has all of that and get its mass. Once I have that mass, I divide it by a factor of 0.15 to get a theoretical takeoff mass (and then try to design the rest of my plane so that it goes under that mass). From that theoretical mass I get the number of engines I need and the amount of fuel I'm going to want. Next step after that is to divide the theoretical takeoff mass by the desired wing loading, which once again for most of my designs is 0.5; you can go higher or lower as you wish, but 0.5 works for me.

Dividing by 0.5 is the same as multiplying by two. So in your case, you've got 178 tonnes of aircraft. 178 / 0.5 = 178 x 2 = 356 square meters desired wing area.

I do a lot of cranked arrow designs (I use a rough analogue of the shape of the Space Shuttle's wings as a guide) and I use Procedural Wings, so my calculator spreadsheet then goes into specifics about how long the various bits should be once I've determined my wing loading, with the length of the fuselage coming into play here.

I could make the calculator available for download, though I'd have to clean it up quite a bit first; I didn't exactly design it for anybody's use besides my own. 

[Gordon Fecyk]

@capi3101 Thanks so far for the assistance.

I don't have the craft file available now, but I redesigned the craft to use twelve Big-S wings including the two horizontal tail planes, two Big-S tails, and supporting control surfaces. That gives 180 m² horizontal wing surface with about the same wing span. Also removed one pair of Whiplashes and tank sets, reducing the fully loaded mass to around 150 tonnes. That's still a wing load of 0.83 t/m², but I also found I need a lot less Liquid Fuel (-2000 units), so I can reduce that mass to 140 t and get wing loading down to 0.77 t/m².

That's still very high based on your recommendations, but the craft seems to fly better now. FAR still complains about some sideslip numbers at speeds below Mach 0.4 at sea level, but if I can reach 150 m/s or more on take-off it can manage. On return, the empty craft's stall speed is down to 90 m/s and I can land without drogues. Barely.

The updated design resembles an @AeroGav creation he calls the "Auto-Ray," just scaled up. It uses his 'wave-rider' style of ascent, accelerating to around 1100 m/s at 18-20 km up before igniting the Aerospikes, then slowly climbing / riding the edge of the middle atmosphere until orbital speed. I have to keep a 6-10 degree angle of attack up there until I get close to 2 km/s, so I might fiddle with wing angles to compensate.

Edited August 9, 2017 by Gordon Fecyk
Grammar

[capi3101]

2 hours ago, Gordon Fecyk said:

@capi3101 Thanks so far for the assistance.

I don't have the craft file available now, but I redesigned the craft to use twelve Big-S wings including the two horizontal tail planes, two Big-S tails, and supporting control surfaces. That gives 180 m² horizontal wing surface with about the same wing span. Also removed one pair of Whiplashes and tank sets, reducing the fully loaded mass to around 150 tonnes. That's still a wing load of 0.83 t/m², but I also found I need a lot less Liquid Fuel (-2000 units), so I can reduce that mass to 140 t and get wing loading down to 0.77 t/m².

That's still very high based on your recommendations, but the craft seems to fly better now. FAR still complains about some sideslip numbers at speeds below Mach 0.4 at sea level, but if I can reach 150 m/s or more on take-off it can manage. On return, the empty craft's stall speed is down to 90 m/s and I can land without drogues. Barely.

The updated design resembles an @AeroGav creation he calls the "Auto-Ray," just scaled up. It uses his 'wave-rider' style of ascent, accelerating to around 1100 m/s at 18-20 km up before igniting the Aerospikes, then slowly climbing / riding the edge of the middle atmosphere until orbital speed. I have to keep a 6-10 degree angle of attack up there until I get close to 2 km/s, so I might fiddle with wing angles to compensate.

Glad to hear the aircraft is flying better for you now. Are you having sideslip issues at landing? 

The ascent profile you're describing sounds about right - you want to be going at least 1000 m/s at 20,000 m or it becomes increasingly unlikely you're going to go to space today. I typically wait to pitch up until I'm going 1200 m/s at 20,000 unless it looks like I'm going to burn something up if I don't pitch, and then I crank it up as hard as the plane will go (I'm still generally lucky if, at first, I get better than ten degrees above the horizon). I design my craft to have about 1500 m/s of delta-V in the rocket phase of the flight; that gives you a little wiggle room for a comparatively mediocre ascent and still leaves enough for de-orbiting. A wet-to-dry ratio of about 1.6 works for most of the rocket engines you'll want to use, and twenty kilometers up is good enough to use the vacuum Isp for the rocket engines. Just telling you all this to see if you might be able to optimize your fuel load a skosh more.

[Gordon Fecyk]

1 hour ago, capi3101 said:

Are you having sideslip issues at landing?

The craft seems to want to pitch up when it's empty and on runway approach. I can rebalance fuel to fix that, and I've already set up tank priorities to drain rearmost tanks and wet wings first. Sideslip is still there but it seems manageable; I might try adding strakes to the wing edges to help with that.

Haven't had a chance to try since then, but it shows a lot of promise.

[capi3101]

58 minutes ago, Gordon Fecyk said:

The craft seems to want to pitch up when it's empty and on runway approach. I can rebalance fuel to fix that, and I've already set up tank priorities to drain rearmost tanks and wet wings first. Sideslip is still there but it seems manageable; I might try adding strakes to the wing edges to help with that.

Haven't had a chance to try since then, but it shows a lot of promise.

If you're not adverse to using mods, one you might consider installing is RCS Build Aid (can confirm it's working in 1.3). Though primarily designed to help you balance RCS thrusters, one of its features is a "dry center of mass" ball. For aircraft, it will give you an idea of how your CoM is going to move around as your fuel drains. Just a suggestion. If it's looking like your craft's going to go unstable, then generally pumping fuel around is a viable solution (provided you have any to pump around, of course), as is redesigning the craft to account for the shift (trouble can arise here if the craft's CoM shifts significantly backwards during flight; account for it with a redesign and you might wind up with a lawn dart at take-off). 

As long as everything's managable, you're probably golden at this point.

[Gordon Fecyk]

And here we are:

The Fat-Star McTater-Tot 2.51:

It's still picked up a bit of mass, at just under 166 tonnes including 36 t cargo, but this is a longer and wider version. Total wing surface is 180 m² and fully loaded it is an obscene wing load of 0.92 t/m², but this thing is unusually nimble like an oversized fighter thanks to its manta ray-like wing configuration. The elevons act as air brakes.

Cargo capacity: At least 36 tonnes and four crew to 100 km low Kerbin orbit, with a little bit of dV to manoeuvre and return. If you need more dV in space, try adding FL-T200 tanks to the front of the outer nacelles, or replace the Mk1 structural fuselages with FL-T400s.

Power plant: 6 x JX-4 Whiplash, 4 x T-1 Aerospike.

Note that the rearmost wet wings are empty to keep the centre of mass further forward. Add Liquid Fuel if you must, for instance to spend more acceleration time on the Whiplashes if needed, but be mindful of the plane's balance. Tank priorities are set to drain from rear to front.

Craft file here (18 KB ZIP). Full instructions are in the craft description. Full stock parts, designed for Ferram Aerospace on KSP 1.2.2 and 1.3.0; change the version value to load the craft in 1.2.2.

Edited August 10, 2017 by Gordon Fecyk

[AeroGav]

A few months back i made this high altitude fighter -

https://www.dropbox.com/s/npvt6gz6fxy4ymc/scion ssto.craft?dl=0

Rather than install BDArmoury,  I decided to mount a pair of nukes under the wings instead.    There's small chutes on each nuke pod so they can land intact and be recovered after separation.

Spoiler

 

Hypersonic L/D ratio.    Quite a lot more lift up here than i thought there would be..  FAR experts, how's my L/D ?

Spoiler

 

Made it to space, I was a bit disappointed not to have enough fuel to go anywhere interesting, but Val liked the view anyway.    BTW I tried "firing" the nukes as torpedoes at a space station,  but they don't go straight.

For re-entry I held full back stick.   For a "fighter" this thing really lacks control authority.   Massive lift in the middle atmosphere means we don't even start to fall down into the heating zone till below mach 4,5

I released the nukes into the water just outside KSP, thanks to the chutes they splash down without damage. Coming in over the threshold..

Spoiler

 

 

Looks like i grossly overestimated our stall speed. Floated down the runway, wasn't ready to land until we were nearing the hills on the other side.

Spoiler

 

 

[Van Disaster]

@Gordon Fecyk  You don't need to calc wing area in FAR, just look at the reference area in the static derivative panel. Don't forget you'll get lift from non-wing pieces, so it's better to use that than try and work it out.

[Elmetian]

 

I recently finished tweaking my crew return vehicle for KSP version 1.2.2 and FAR. It is made entirely from stock parts, and it's 90% recoverable if launched into an equatorial orbit, including a 1st stage which lands SpaceX style on the peninsula to the East of the KSC. The only thing that is discarded is the service module.

The CRV itself is a glider, and because it has such a small wing area it tends to stall below about 90m/s. This made it very difficult to land on wheeled gear. They also added a lot of mass, making the fuel margins for the 1st stage landing much much smaller, so I eventually replaced them with parachutes a bit like the X-38's parafoil. Speaking of which, if someone could make a parafoil mod for KSP that'd be great.

You can download the craft on KerbalX here. I've included an album below showing the CRV and booster in more detail (the images are huge thanks to supersampling, so make sure to zoom!):

 

Edited August 25, 2017 by Elmetian

[capi3101]

49 minutes ago, Elmetian said:

Speaking of which, if someone could make a parafoil mod for KSP. <snip />

You mean kinda like the one mentioned here? Just released a few days ago...

[Elmetian]

58 minutes ago, capi3101 said:

You mean kinda like the one mentioned here? Just released a few days ago...

Thanks! I had a cursory search of the forums a few hours ago to see if anyone had made a parafoil but found nothing other than the ones on the Contares spaceplanes. Going to try this out tonight.

Do you know if it collapses after you land like parachutes do? Also it looks like the part needs to be mounted horizontal. Do you know if it still works if the part is mounted at an angle?

Edited August 25, 2017 by Elmetian

[capi3101]

2 hours ago, Elmetian said:

Do you know if it collapses after you land like parachutes do? Also it looks like the part needs to be mounted horizontal. Do you know if it still works if the part is mounted at an angle?

I don't use this mod myself, so I can't really answer the question. @NISSKEPCSIM is the creator of the mod; he probably would be your best bet for trying to answer your questions.

[NISSKEPCSIM]

In the OP of Notantares, you'll see some special attachment instructions highlighted in big, red, bold letters, hidden by a spoiler. Read those. They are very important. 

It doesn't work if mounted at an angle, because that's just like pointing a wing down - it generates down force rather than lift. It doesn't collapse on landing, because the Gemini paraglider, which it was based off, when deployed had kind-of rigid wires holding it up. Also, the mod CONTARES has a proper parafoil, and by proper, I mean it's based off of the one used on the X38. Both need to be mounted horizontally.

@Elmetian

[Elmetian]

On 8/26/2017 at 10:07 AM, NISSKEPCSIM said:

In the OP of Notantares, you'll see some special attachment instructions highlighted in big, red, bold letters...

Also, the mod CONTARES has a proper parafoil, and by proper, I mean it's based off of the one used on the X38. Both need to be mounted horizontally.

@Elmetian

Thanks. I'm going to try them both out when I get a chance

[Kitspace]

Hello!

I am having some difficulties with one craft that I am trying to design for my kerbal fleet.

The plane that does not yet have its name is intended to be a conventional long range cargo transport. It should be capable of relatively quickly moving and deploying various things at different locations around Kerbin such as exploration probes or crew recovery parties for those kerbals who managed to land in the middle of nowhere on the way back from space.  A possibility of paradropping items mid flight is also considered.

 

The main thing about it is the balance and stability. The center of gravity seems way way too far forward so that the tips of the main wing and not the stabilizer are responsible for the majority of the static pitch stability. While it may be kinda acceptable in cruise it is absolutely horrible for proper takeoff and landing as the thing lacks the control authority even with ridiculously high stabilizer incidence angles. The problem is that I can not possibly move the wing forward as in its current position the main gear bogies are almost directly below the center of mass. So either I have to drop the airliner style landing gear attachment and snap them into some other place which I do not really want to do or find another way to make the plane less stable.

How can I fix this? How is this current arrangement different from the real life designs of the same type? I guess with a highly swept back wing and the gear attached at its root large portions of that wing just have to be behind the center of mass anyways. And that kerbal wing is really not the most sharply swept one even amongst the airliners...

 

The second question is how to make the flaps more effective? Currently as seen on the derivative pages their effect is quite marginal or even negative when the angle is too high. Even when thinking of them as simple hinged non slotted flaps in the real world terms I would expect them to easily deploy to fifty or sixty degrees for landing. Or are they by any chance modeled as some type of slotted or fowler flaps? In the static page on the graph we see that the coefficient of lift never exceeds 2. To me seems quite low for takeoff or landing with flaps.

 

Also the level flight angle of attack value does something that I do not quite understand. When I decrease the speed for which it is calculated it increases to some value but then just suddenly goes zero. It does not approach the stall angle of attack. Does that mean that the plane can not fly slower than that for some other reason even though it is not stalling? Or is it just the prediction algorithm having trouble computing?

 

Any help will be strongly appreciated!

Thank you!

Pictures

https://imgur.com/a/cT0yg

Edited September 1, 2017 by Kitspace

[capi3101]

1 hour ago, Kitspace said:

Hello!

The main thing about it is the balance and stability. The center of gravity seems way way too far forward so that the tips of the main wing and not the stabilizer are responsible for the majority of the static pitch stability. While it may be kinda acceptable in cruise it is absolutely horrible for proper takeoff and landing as the thing lacks the control authority even with ridiculously high stabilizer incidence angles. The problem is that I can not possibly move the wing forward as in its current position the main gear bogies are almost directly below the center of mass. So either I have to drop the airliner style landing gear attachment and snap them into some other place which I do not really want to do or find another way to make the plane less stable.

The second question is how to make the flaps more effective? Currently as seen on the derivative pages their effect is quite marginal or even negative when the angle is too high. Even when thinking of them as simple hinged non slotted flaps in the real world terms I would expect them to easily deploy to fifty or sixty degrees for landing. Or are they by any chance modeled as some type of slotted or fowler flaps? In the static page on the graph we see that the coefficient of lift never exceeds 2. To me seems quite low for takeoff or landing with flaps.

Can you show us your current control settings on your flaps? Flaps and spoilers have a separate control slider from pitch, yaw and roll, and it's easy to overlook (to this day when I'm doing early aircraft and I want to add a spoiler, I'll usually forget to bump this setting up to maximum deflection and wind up with some wimpy 15-degree setting, when what I want was the full 85-degree makeshift airbrake setting). For that matter, what do the settings look like for each of your control surfaces?

Given the position of the wing, if the rear wheels are lined up with the CoM (like i think you're saying), the plane should have sufficient control authority - that's just me looking at it though. Your control settings may (once again) explain a few things. Could you also provide a picture with your CoM ball turned on, just to make sure I understand what's going on with the aircraft? For good measure, go ahead and turn on your CoL ball too. It may not tell us anything, and then again it might.

[Van Disaster]

Zero on the info panels means you've stalled ( or perhaps gone out of bounds of that particular simulation - I think AoA over 30 might do that, I'd have to dig up a plane with the ability to pull really huge AoA to check it & I can't remember what I did with one ). Flaps are currently just modelled as wing pieces iirc, so they will stall like a wing piece - I don't think I've had usable flaps with more than about 40-45 deg deflection, and there's a small part of the envelope you can use that sort of deflection. If you want to make them more effective, make them larger. I believe in your flaps 3 pic you've actually stalled the flaps, given your cD is triple that of flaps 2, that would explain the loss of lift & higher AoA.

If you get nothing else, I would get a procedural wing mod for building FAR craft.

Flaps on this are limited to 20 degrees, but they're so large they work very well. Any more deflection & they'll stall, especially with the aircraft itself pulling AoA. ( I probably wouldn't fly this slowly though - nice to know it can do it ).

Edited September 2, 2017 by Van Disaster

[Kitspace]

Sorry for the late reply. Did not have the chance to get to my computer sooner.

Here are the pictures with the center of mass and controls

https://imgur.com/a/ohfRg

I do use the procedural parts mods. Some of the controls on this craft are procedural for example.

Regarding the computed level flight angle of attack. I am puzzled because with most of my planes it goes blank at a seemingly random value. It does NOT by any means approach the critical angle of attack or the maximum lift coefficient shown on the static stability page. For example the maximum lift coefficient on this plane is about 1.2 while the level flight window goes blank at about of half that and at an angle of attack of just 10 degrees.

[Van Disaster]

Hum. Can you take a shot of the statics panel with it all zeroed? caveat - I'm still running 1.1, because I haven't played since 1.2 came out & I haven't upgraded my own mod yet  - so there could be some new behaviour in the last two FAR versions. If the panel goes *completely* blank then you want to check your logfile for NREs I suspect, because that sounds like a bug & probably not one in FAR. 

Note the >0 AoA in the derivatives, iirc that means it's gone out of bounds which I'm pretty sure *is* 30 deg AoA but not 100%. It does look like the craft is stalled though given the enormous drag. I presume that isn't what you're seeing.