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

[NathanKell]

So in other words you just invented MOL / DORIAN.

[Subcidal]

Does the newest version work with .23?

[BudgetHedgehog]

I knew you could store more than one eva report, and surface sample but only one crew report....

You can, you just have to treat it as any other data i.e. remove it from the pod (right click, remove data) and then store it again (either by entering or right clicking and storing data). Not that there's much point because they transmit at 100% anyway. I suppose though if power is an issue, like in early career game, transmitting isn't a viable option.

[Read have Read]

I am trying 13.2 and I really like the new Airspeed displays, the Km/h especially helps to visualize the difference between .2 and .3 mach and making it match realistic designs.

Now, I got a little confused installing the .dll from Github, so I might have induced errors, like the Data + stability analysis window calculating to 16 digits. I tried a large 200t SSTO and my flaps and/or elevons were quickly introduced to Aerodynamic Stresses shortly after lift off. A little bit of adaptation - reducing G's and Q's and things seem to be flying fine.

I like it, thanks Ferram.

[phoenix_ca]

Regarding experiments, there are two mods that make the management of data much simpler, Ship Manifest, and...Radial Science Container I think it's called.

And completely unrelated...I hope MJ2 sees some FAR support soon for ascent profiles. All it *really* needs to work is an AoA limiter.

[ferram4]

@Subcidal: No reason it shouldn't. It's not calling anything that requires 0.23.5.

@Read have read: Good to hear! Thanks for pointing out the numbers in the Editor, I switched a lot of stuff from floats to doubles and I didn't cut off the digits at the same value. Hopefully I can get the full version out soon.

@phoenix_ca: Really, the best way for MJ to handle ascent for FAR is this:

Set a turn start altitude; below this it's vertical.

Set an initial turn angle, and once it reaches the start altitude the rocket shifts to that orientation.

Once the prograde marker drops below that turn angle, the rocket follows prograde until...

The safe altitude / dynamic pressure is hit, where it can orient off of prograde to finish the ascent.

Because then it can do whatever it wants above a certain altitude, but below that it simply gives up on fighting aerodynamics and goes with the flow.

[NathanKell]

Or, if you want to use ascent guidance (just use smaller turn-end altitude for non-RSS play).

[KerbMav]

Does FAR change whether an engine is obstructed or not?

O-Doc tested one of my planes and it not even got of the runway in his game, I am using FAR, he is not - he thinks that the wings behind the jet engines block the air stream.

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[Zeroignite]

So, I'm getting more and more tempted to hop on board with team FAR. Still a couple questions/concerns:

1, is there any way to semi-accurately predict aerocaptures? I'm ok using a web or clientside tool for this.

2, how well does FAR play with Deadly Reentry? I've heard rumors that it makes things a lot more burn-up-y when you hit ~30km.

[BudgetHedgehog]

So, I'm getting more and more tempted to hop on board with team FAR. Still a couple questions/concerns:

1, is there any way to semi-accurately predict aerocaptures? I'm ok using a web or clientside tool for this.

2, how well does FAR play with Deadly Reentry? I've heard rumors that it makes things a lot more burn-up-y when you hit ~30km.

1, not really. F5 and F9 will be your best friends regarding aerobraking and aerocapture.

2, don't quote me on this because I don't have DRE, but I think FAR actually makes it a bit easier.

[taniwha]

So long as you don't care about the exact apoapsis after capture (so long as it's out of the atmosphere), I've found that FAR doesn't make a huge difference. At least sufficiently so such that stock model figures for a safe capture are good for a first-guess.

When it comes to DRE, it's not that bad: The main source of "DRE+FAR=bad news" comes from DRE 1.3 with the really bad heating model. I had a terrible time landing anything with 1.3+FAR (never tried without FAR). With 2.0+, most of my Kerbin-SOI reentries are rather "ho-hum, flames are pretty". That said, ship mass makes a huge difference: A ship with full tanks and the same ship with empty tanks on the same reentry orbit will have radically different outcomes. The ship with full tanks will stay fast longer and thus is more likely to burn up. The ship with empty tanks will decelerate much faster and thus be more likely to suffer acceleration damage. However, that depends greatly on the reentry orbit.

FAR makes it easier to get into space, but more complicated to get back However, it's not all bad: for consistent results know your ship and fly consistently. Also, with aerobraking in FAR, once you start get into some real deceleration, you won't have much choice about the orientation of your vessel, so being consistent won't be all that difficult.

[Zeroignite]

Great answer! Quicksaving/loading before and after aerocapture isn't too bad; not something I really like but I assume I'll get used to differences and tune in my offset In general I'll do more conservative aerocaptures and pack a bit more delta-v to circularize... which is probably good practice anyway, really.

Are there ship configurations that will tend to result in severe heatshield-towards-space on reentry, apart from things like fins on the bottom?

[federally]

The only real affect I've seen FAR have on DRE is simply maintaining a proper orientation of the ship. If your craft had poor aerodynamics you will find it difficult if not potentially impossible to point your heat shield towards the danger. So proper design of your reentry vehicle is required.

This makes things more realistic and better in my opinion.

When I have a well designed craft I just turn off SAS once I've entered the atmosphere and let FAR take over and orient the ship for me.

[undercoveryankee]

The only real affect I've seen FAR have on DRE is simply maintaining a proper orientation of the ship. If your craft had poor aerodynamics you will find it difficult if not potentially impossible to point your heat shield towards the danger. So proper design of your reentry vehicle is required.

This makes things more realistic and better in my opinion.

When I have a well designed craft I just turn off SAS once I've entered the atmosphere and let FAR take over and orient the ship for me.

I think my crew transfer vehicle (2 hitchhikers between the command pod and the 2.5m heat shield) is long and thin enough to be lower-drag in FAR than it would be in stock. Those drag variations can affect the entry angle you need. (If FAR calculates that your heat shield is shielded by the fairing just above it, you're in for a wild ride.)

[S.O.P.H.I.A.]

I've located what may be a bug, or may be an unexpected feature; I can't tell.

I went for a while from early KSP .23 until now without updating FAR, and I found that in the new FAR, turbojet engines are dramatically less powerful. They cut out at around ~1500m/s regardless of the amount of air I have left, meaning that planes that could get to around 1000km apoapsis without switching to rockets can now only get to around 24km. This is probably realistic, and not terribly unexpected.

The really surprising bit is that RAPIER engines are now *more* powerful. At high speeds, when a turbojet is barely outputting 1kN, open-cycle stock RAPIERs are over 100kN. The reason I'm surprised is that I'd always considered RAPIERS to be a bit of a compromise between rockets and jets--you get a less-effective jet by mass than the turbojet and a less-effective rocket than the aerospike in exchange for having both for overall less mass and size. But now, the RAPIER is a better *jet engine* than the specialized turbojet, leading to some weird designs. My new-generation fleet uses RAPIERs instead of Turbojets, but never switches to their rocket mode, instead using a nuclear rocket motor. It seems strange to me that two RAPIERs (without ever using their rocket mode) and a nuclear engine is vastly more effective, except at low altitudes/speeds, than two Turbojets and a nuclear engine.

OTOH, according to wikipedia, the SABER engine that the RAPIER is based off of has incredible high-speed/high-altitude performance, so maybe this is intentional, and my perspective of the RAPIER being a compromise engine is inaccurate.

Anyway, is this a bug or a feature?

[undercoveryankee]

I've located what may be a bug, or may be an unexpected feature; I can't tell.

I went for a while from early KSP .23 until now without updating FAR, and I found that in the new FAR, turbojet engines are dramatically less powerful. They cut out at around ~1500m/s regardless of the amount of air I have left, meaning that planes that could get to around 1000km apoapsis without switching to rockets can now only get to around 24km. This is probably realistic, and not terribly unexpected.

The really surprising bit is that RAPIER engines are now *more* powerful. At high speeds, when a turbojet is barely outputting 1kN, open-cycle stock RAPIERs are over 100kN. The reason I'm surprised is that I'd always considered RAPIERS to be a bit of a compromise between rockets and jets--you get a less-effective jet by mass than the turbojet and a less-effective rocket than the aerospike in exchange for having both for overall less mass and size. But now, the RAPIER is a better *jet engine* than the specialized turbojet, leading to some weird designs. My new-generation fleet uses RAPIERs instead of Turbojets, but never switches to their rocket mode, instead using a nuclear rocket motor. It seems strange to me that two RAPIERs (without ever using their rocket mode) and a nuclear engine is vastly more effective, except at low altitudes/speeds, than two Turbojets and a nuclear engine.

OTOH, according to wikipedia, the SABER engine that the RAPIER is based off of has incredible high-speed/high-altitude performance, so maybe this is intentional, and my perspective of the RAPIER being a compromise engine is inaccurate.

Anyway, is this a bug or a feature?

FAR intentionally dials the power of the stock jet engines down a little to be more realistic, since you don't need extreme performance to overcome stock drag. The loss of thrust at high speed is an intended part of that tuning, based on the limits of current jet engine technology.

In FAR 0.12.5.2 (which is probably what you would have been running on 0.23), there was a typo in the config file for the Turbojet that allowed it to maintain full thrust at arbitrarily high speed, allowing some aircraft to achieve Kerbin escape velocity in the atmosphere. The 0.13 series restores the intended behavior.

Whether Ferram will dial the RAPIER's air-breathing mode back closer to the other jets or leave it where it is based on what's known about the SABRE is up to him.

[phoenix_ca]

@phoenix_ca: Really, the best way for MJ to handle ascent for FAR is this:

Set a turn start altitude; below this it's vertical.

Set an initial turn angle, and once it reaches the start altitude the rocket shifts to that orientation.

Once the prograde marker drops below that turn angle, the rocket follows prograde until...

The safe altitude / dynamic pressure is hit, where it can orient off of prograde to finish the ascent.

Because then it can do whatever it wants above a certain altitude, but below that it simply gives up on fighting aerodynamics and goes with the flow.

That would be lovely.

[SkyRender]

Quick question: what happened to the many features that FAR added to winglets (such as Control Max and Flap/Brake Max adjustment bars)? I rather appreciated those features, given that the default values tend to cause pretty much anything not grossly over-engineered to go into an absurd flat spin when above mach 2 due to massively over-responsive controls. Are they still there and my install is just being stupid, or did they get nixed at some point? If it's the latter, I'd like to request they be returned, as those default values make oversteering and loss of control at high mach speeds a guarantee.

[ferram4]

@KerbMav: No, those engines would always make no thrust. The engines are always going to be blocked by the wings on that design due to stock engine behavior.

@S.O.P.H.I.A.: Nope, the turbojets were overpowered before. I'll probably bring the RAPIER down to the velocity curve that the B9 SABREs use to balance it out.

@SkyRender: Right-click the part. FAR has used tweakables for that since they were introduced.

[SkyRender]

@SkyRender: Right-click the part. FAR has used tweakables for that since they were introduced.

Yeah, I realized that a file hadn't extracted correctly when I installed FAR. Once I re-extracted it and overwrote the corrupted version, the tweakables returned. Thanks!

[NathanKell]

Just to show FAR works at the other end of the spectrum too, here's my electric STOL light plane. Stalls at 45kts, cruises at about 60, max speed about 110. Uses Firespitter foldable electric thrust-limited to 5.5%

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[DaMichel]

Nice! Looks like the real thing.

You could try the Flying on Duna challenge. It involves plenty of flying low and slow The light planes i made for it are pretty similar to this one except for the canopy and the wings being mounted low. Nice landing btw

[AndreyATGB]

I've got a few questions about wing placement. Assuming the center of lift stays at the same place with the wing area being constant, what's the difference between placing the wings in the middle of the fuselage (Y-axis/vertically), top or bottom?

Also when do you need a tailplane, the ones with horizontal aspects as well and when is a vertical stabilizer enough?

[KerbMav]

@KerbMav: No, those engines would always make no thrust. The engines are always going to be blocked by the wings on that design due to stock engine behavior.

Then I do not know by which witchcraft they do on my end and not on Doc's ...

A mystery to solve!

[DailyFrankPeter]

Does anyone else get more sideslip with FAR 13.1 than before? Or perhaps it's KSP 0.23.5?