[1.3.1] Ferram Aerospace Research: v0.15.9.1 "Liepmann" 4/2/18

[Hodo]

Not true. Check the MM file.

Well nothing like AJE. It changes the speed scale mostly. But I have never played with stock KSP. I have had FAR since and hour after I installed the game, lol.

Two first mods, DRE and FAR.

[thorfinn]

As far as AJE - all the speed and altitude curves for jets in B9 and TVPP were done based on data from NASA EngineSim, and AJE is NASA EngineSim implemented as a PartModule.

So it shouldn't be too different from what I'm used to by now - besides the fuel consumption. Good to know; I wanted to try it, but I wouldn't like an overly punishing change (i.e. I still want to be able to make jet+rocket SSTOs)

[Taverius]

So it shouldn't be too different from what I'm used to by now - besides the fuel consumption. Good to know; I wanted to try it, but I wouldn't like an overly punishing change (i.e. I still want to be able to make jet+rocket SSTOs)

Well, not really ... one key thing the stock jets miss is thrust decreasing with air density ... which AJE has.

The max speeds of the engines are comparable to what B9/TVPP/FAR give you, but the specifics of the behaviour are quite different, because the stock engine module basically doesn't model jets at all.

[K3-Chris]

Well also have to consider people not using FAR with B9 and overall people that don't bend towards simulation as much, if B9's engines worked the same as AJE a lot of people would wonder why the engines "don't work right".

B9 is too broad of a mod to assume everyone that uses it uses FAR and likes realism. But people that do like realism can MM that on top, or use AJE's engines.

Edited June 10, 2014 by K3|Chris

[NoClass]

Ferram,

First off, let me add to the chorus saying how awesome your work has been. This truly is an accomplishment.

Anyway, I tinkering with basic winged bodies in the SPH; seeing how your analyzer responded to them. I noticed that the calculated Cd doesn't seem to change much with increased AoA:

Does this mean that the Cd of the analysis only accounts for profile drag with increased AoA? Regardless, shouldn't profile drag spike if the wing is beyond the critical AoA?

Also, I'm having a difficult time designing craft that can glide slowly. I figure that's due to the relatively high density of KSP parts (thus, high wing loading), but I dunno...

Still, with most of my craft it FEELS like the drag at high AoA and low a/s isn't high enough, as if lift-induced drag isn't a factor. Is there any way in the current version of FAR to look at that?

...or are all of these questions evidence that I simply don't understand aerodynamics properly

[ferram4]

The lift induced from drag is the only drag that's actually calculated for wings (with profile drag increases simply folded into that); there's no reason to separate them, that just makes things more confusing for people, and they're both drag. On the graph, the reason it looks wrong is that drag and lift are placed on the same scale, and drag is often more than an order of magnitude lower than lift, so it doesn't appear to change as dramatically. The Cd curve doesn't change that much on the other side of the stall AoA, it just continues increasing while lift decreases. As for feeling like there isn't enough drag, the numbers are correct, your feelings are wrong.

I'll admit that I'm confused by the combination of not having enough drag and not being able to glide well, unless that means that you're just not bringing enough wing along.

[NoClass]

On the graph, the reason it looks wrong is that drag and lift are placed on the same scale, and drag is often more than an order of magnitude lower than lift, so it doesn't appear to change as dramatically.

Ahh, now that makes sense! I guess that I'm used to seeing those coefficients on graphs with multiple scales. Maybe it's time to start paying attention to what I read...

I'll admit that I'm confused by the combination of not having enough drag and not being able to glide well, unless that means that you're just not bringing enough wing along.

That is a beautiful response! I'll clarify and say that my planes have good glide ratios, but I trouble getting them to fly slowly with the power off. Of course, more induced drag would not make this any easier, so I'll shut up now. Thanks for the info!

[horndgmium]

Hey, so I've got a bone to pick with the newest far. First of all, my planes have been falling apart at about 7g and we're fine before. That wouldn't annoy me so much, however, if we had intended to fly our planes Asa conglomeration of pieces. While you may make the argument that I'm putting too many g forces on my planes and that parts should fall apart, I think that's the wrong way to look at ksp crafts. The planes I build are intended to be one flying thing, not a bunch of parts strewn together. So I must ask if 1. Aerodynamic stress 9 toned down in the future and 2. If aerodynamic stress would cause parts like aerofoils to malfunction, rather than say, make the wings fall off, because I'm sure you realize which is the more likely of the two irl.

Just some thoughts.

[NathanKell]

What do you even mean, "cause...airfoils to malfunction"? You think aluminum's response to too much torsion is to politely stop making lift,

As Ferram has pointed out many times in this thread

(1) stress failures are gentler than real life. It's just that y'all have gotten so used to doing impossible things in KSP that a bit of reality therapy feels like utter hell.

(2) you can turn it off in settings anyway.

[ferram4]

I think what he means by "cause the airfoils to malfunction" is that the wings should bend and twist in an oscillatory manner first, before those oscillations grow and destroy the vehicle. So if I'm interpreting this right, we're talking about a request for flutter, and thus, failure at even lower speeds and wing loadings. You know,

.

Sounds like a good idea, it is in the plans, eventually.

[Fatchicken]

Once mach number reaches 1, my plane's nose starts to slowly point down, regardless of my input. What can i do about this? Everything seems to be normal, right? _right?

[taniwha]

NathanKell: I hope that pilot was wearing his brown pants.

[Camacha]

Once mach number reaches 1, my plane's nose starts to slowly point down, regardless of my input. What can i do about this? Everything seems to be normal, right? _right?

It seems to suggest there is something that causes more drag on the bottom of your craft than on the top, slowly overpowering your control surfaces. Another option might be those double fins, I am not sure how they are pointed, but make sure they do not push your craft down.

[thorfinn]

Once mach number reaches 1, my plane's nose starts to slowly point down, regardless of my input. What can i do about this? Everything seems to be normal, right? _right?

We can't see your picture; it's Mach tuck, anyway. Most (all?) planes tend to nose down when going supersonic because the center of lift moves backwards. The easiest thing to do is adding lots of control authority in pitch to counteract it. I don't know what would be the best wing shape to reduce the effect, whoever knows please write it in the wiki

[K3-Chris]

One solution is to make your plane's CoM and CoL pretty far back already, makes the shift smaller.

[entaran]

After being told fairly bluntly by ferram about 50 pages ago that I was bad at plane design after I complained about planes blowing to pieces too easily...

I can now get 100 ton SSTO's to orbit and home without even the slightest hiccup. (Using B9 parts)

Pretty proud even though it's taken three solid weeks of teaching myself aerodynamic design... and getting much better at keyboard control because I don't have/use a joystick.

RE: The mach nosedive, if you take the main body of your plane and then extend the nose forward using fuselage sections or similar, you'll find that the COM/COL moves way further back on the plane (it doesn't move at all, but the plane gets longer away from it), this will SIGNIFICANTLY increase your stability and reduce the effect of this.

This SSTO is 97 or so tons at takeoff weight. Has a TWR of 1.40 down the runway and will lift before the end (at approx 150m/s nose up, 175m/s ground clearance). Can ascend at a solid 20-25 degrees to 15km, then level out to about 7-8 degrees to build up speed to about mach 4.5. It has zero wobble, zero mach nose dive, and requires minimal trim to fly on all the current latest versions of each mod. It's designed as a tanker and takes the equivalent of a bit over a full orange tank to orbit after its own fuel use to get into orbit, rendezvous, dock and then de-orbit. Product of many weeks of trial and error!

If I give it to mechjeb to fly, it explodes instantly. Unless it's already at about 10km where the atmospheric pressure is significantly less.

Pretty much designed it to see if I could make a completely re-usable fuel tanker from KSC to LKO to refuel stations or interplanetary stages etc. Can basically just taxi up to my orange tank stack,refuel and take off again no worries!

[Hodo]

What do you even mean, "cause...airfoils to malfunction"? You think aluminum's response to too much torsion is to politely stop making lift,

As Ferram has pointed out many times in this thread

(1) stress failures are gentler than real life. It's just that y'all have gotten so used to doing impossible things in KSP that a bit of reality therapy feels like utter hell.

(2) you can turn it off in settings anyway.

I hate that video....

1- it is fake.

2- it is obviously fake.

Sorry.

[BudgetHedgehog]

[Hodo]

Nope, he suffered a wing root structural failure most likely due to overstress and airframe age.

[horndgmium]

What do you even mean, "cause...airfoils to malfunction"? You think aluminum's response to too much torsion is to politely stop making lift,

As Ferram has pointed out many times in this thread

(1) stress failures are gentler than real life. It's just that y'all have gotten so used to doing impossible things in KSP that a bit of reality therapy feels like utter hell.

(2) you can turn it off in settings anyway.

Well like I said, sometimes it happens at 3g even. It pulled the command pod right off the fuel tank, which is kinda ridiculous.

I don't have a solution, just throwing out some alternative, that is all. Yes, aluminum's response to stress is to rip, which is an outrageous suggestion due to the amount of work required to make that happen, especially visually, in KSP. But I do like the idea of flutter.

Edit: I forgot to mention, it happens when re-entering as well, which makes it especially hard to pitch up when doing so.

Edited June 12, 2014 by horndgmium

[Hodo]

Well like I said, sometimes it happens at 3g even. It pulled the command pod right off the fuel tank, which is kinda ridiculous.

I don't have a solution, just throwing out some alternative, that is all. Yes, aluminum's response to stress is to rip, which is an outrageous suggestion due to the amount of work required to make that happen, especially visually, in KSP. But I do like the idea of flutter.

Edit: I forgot to mention, it happens when re-entering as well, which makes it especially hard to pitch up when doing so.

Use struts.

I am currently making aircraft that can handle well in excess of 9Gs. B9 has some wonderful invisible struts which are great, and they are stronger than the stock struts.

[razorblade75]

is there a tutorial to power landing with ferram? i keep crashing,and crashing, and crashing...poor jeb

[camlost]

So it shouldn't be too different from what I'm used to by now - besides the fuel consumption. Good to know; I wanted to try it, but I wouldn't like an overly punishing change (i.e. I still want to be able to make jet+rocket SSTOs)

It's a lot harder but totally possible to make SSTOs, on Kerbin or Earth

Well also have to consider people not using FAR with B9 and overall people that don't bend towards simulation as much, if B9's engines worked the same as AJE a lot of people would wonder why the engines "don't work right".

B9 is too broad of a mod to assume everyone that uses it uses FAR and likes realism. But people that do like realism can MM that on top, or use AJE's engines.

I think the jet+intake system is just a very BAD implementation from the beginning -- too cheaty and buggy. To balance anything you need at least something like FSEngine

[Sparker]

But I do like the idea of flutter.

Try to make a wing of very many little wings. It will bend and maybe even oscillate at high speeds. I had such a problem with one of my planes.

[Hodo]

is there a tutorial to power landing with ferram? i keep crashing,and crashing, and crashing...poor jeb

It is easy...

Step 1- Line up for final approach.

Step 2- Decrease your rate of decent to less than 10m/s.

Step 3- Deploy Flaps as needed, and lower landing gear.

Step 4- Just before you touch down, flare your nose up a few degrees to bleed off excess speed.

Step 5- Touchdown! Keep your nose up at 5-10deg until your speed drops enough for your nose to touch down. Apply brakes as needed.

Step 6- Park your craft, get out admire your awesome landing!