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

[TeeGee]

Hey everyone I need some help. Is there any tutorials to help us redesign our aircraft and spacecraft in ferram? My previous SSTO that I designed is actually amazing in FAR but I am having issues with shaking during lower altitude ascent and descent. How can I design my craft to avoid having such violent shakes?

[BananaDealer]

@BananaDealer: Bug reports like that without a copy of the output_log.txt aren't much use. I have no idea what's breaking, only that something's breaking and that I've never seen that issue before. Post the log (not KSP.log) and we'll see if anything useful can be found in it.

I'll reproduce the bug and get you a log as soon as I get the time...

Edited March 18, 2014 by BananaDealer

[pingopete]

Hey everyone I need some help. Is there any tutorials to help us redesign our aircraft and spacecraft in ferram? My previous SSTO that I designed is actually amazing in FAR but I am having issues with shaking during lower altitude ascent and descent. How can I design my craft to avoid having such violent shakes?

Get the latest Kerbal Joint Reinforcement if you havent already.

Attach the external tank to a radial decoupler directly on your SS.

KJR makes radial decouplings insanely strong, on RSS I've had a 300+ ton external tank solidly attached to the 1st stage with one decopler.

It's hard to suggest though without seeing your ship, I've finally got my shuttle working smoothly, into orbit, and reentering :'D

[White Owl]

I'm returning to KSP after a few months off, and I find FAR has advanced to a point where I no longer know how to use it.

How do I find out the correct amount of control surface deflection nowadays? The tweakable right-click menu allows me to set the deflection, but I can't figure out how to get FAR to tell me the stall angle like it used to. It isn't in the "sweep AoA" panel anymore. It isn't in the tweakable menu. Not in the action group options... What else is there?

[TeeGee]

Get the latest Kerbal Joint Reinforcement if you havent already.

Attach the external tank to a radial decoupler directly on your SS.

KJR makes radial decouplings insanely strong, on RSS I've had a 300+ ton external tank solidly attached to the 1st stage with one decopler.

It's hard to suggest though without seeing your ship, I've finally got my shuttle working smoothly, into orbit, and reentering :'D

No it's not wobbling, it's shaking my craft when I reach higher speeds at low altitudes. It for example, I launch my SSTO (not space shuttle) and the thing starts rolling and shaking when I keep SAS activated and start accelerating. Once I hit thinner air, that stops. The shaking only happens with SAS activated and when I am at low altitudes trying to pick up velocity.

ALSO, when I build a rocket, I am having trouble yawing the craft for my gravity turn at 10km... I have a feeling that doing my gravity turn that late at such a high speed is not the right idea, is there a tutorial of when to initiate a gravity turn with rockets and FAR? My crafts are stable, they just don't turn as well as stock KSP did.

Any design tips?

[John Crichton]

No it's not wobbling, it's shaking my craft when I reach higher speeds at low altitudes. It for example, I launch my SSTO (not space shuttle) and the thing starts rolling and shaking when I keep SAS activated and start accelerating. Once I hit thinner air, that stops. The shaking only happens with SAS activated and when I am at low altitudes trying to pick up velocity.

ALSO, when I build a rocket, I am having trouble yawing the craft for my gravity turn at 10km... I have a feeling that doing my gravity turn that late at such a high speed is not the right idea, is there a tutorial of when to initiate a gravity turn with rockets and FAR? My crafts are stable, they just don't turn as well as stock KSP did.

Any design tips?

I'm new to FAR too, but afaik doing the standard "gravity turn" at 10k isn't the way to go. I think you need to turn more gradually (but I might be wrong, still testing stuff myself).

[taniwha]

ALSO, when I build a rocket, I am having trouble yawing the craft for my gravity turn at 10km... I have a feeling that doing my gravity turn that late at such a high speed is not the right idea, is there a tutorial of when to initiate a gravity turn with rockets and FAR? My crafts are stable, they just don't turn as well as stock KSP did.

Any design tips?

It's not your design, it's your flying. Start your gravity turn somewhere between 50m/s and 100m/s (usually less than 500m altitude), and turn gently: keep your navball marker within the prograde marker. Also, keep your acceleration below 2G until you're pitched lower than 30 degrees.

[TeeGee]

It's not your design, it's your flying. Start your gravity turn somewhere between 50m/s and 100m/s (usually less than 500m altitude), and turn gently: keep your navball marker within the prograde marker. Also, keep your acceleration below 2G until you're pitched lower than 30 degrees.

So I start my gravity turn at lower velocity which is usually maxed out at around 0.5km.

Wow, does that mean my rockets will require more delta v to reach orbit due to the prolonged time it is in thicker atmosphere (drag)?

[BudgetHedgehog]

Wow, does that mean my rockets will require more delta v to reach orbit due to the prolonged time it is in thicker atmosphere (drag)?

Depends on the rocket but usually, it's the opposite. If it's built without aerodynamics in mind, then yes, it'll take more dV to reach orbit. But if it looks aerodynamic, is nice and sleek, has fairings on payloads etc, you can get into orbit on less than 4km/s dV (my record according to MJs "dV spent" stat is 3.4, but I don't know if that's entirely accurate), in contrast to the stock 4.4km/s.

[taniwha]

So I start my gravity turn at lower velocity which is usually maxed out at around 0.5km.

Wow, does that mean my rockets will require more delta v to reach orbit due to the prolonged time it is in thicker atmosphere (drag)?

If your velocity maxes out around 0.5km, you're doing something very wrong. Like flying a brick out-house with a barn door attached, with way too much power. While plenty of power is good for reducing gravity drag, it makes you go too fast and thus lose control authority and also suffer more at the hands of side-slip induced forces.

[TeeGee]

Depends on the rocket but usually, it's the opposite. If it's built without aerodynamics in mind, then yes, it'll take more dV to reach orbit. But if it looks aerodynamic, is nice and sleek, has fairings on payloads etc, you can get into orbit on less than 4km/s dV (my record according to MJs "dV spent" stat is 3.4, but I don't know if that's entirely accurate), in contrast to the stock 4.4km/s.

Yeah I noticed that with my SSTO. She reached 30km and I was still accelerating even with my engines off, I hit an apoapsis of 200km at 30km without anymore acceleration and she just kept going until a final apoapsis of 250kmish was made.

[TeeGee]

If your velocity maxes out around 0.5km, you're doing something very wrong. Like flying a brick out-house with a barn door attached, with way too much power. While plenty of power is good for reducing gravity drag, it makes you go too fast and thus lose control authority and also suffer more at the hands of side-slip induced forces.

So then I shouldn't be going full throttle at launch? Or should I use just enough engine power for a >1 thrust to weight ratio?

[Crater]

So then I shouldn't be going full throttle at launch? Or should I use just enough engine power for a >1 thrust to weight ratio?

Somewhere around 1.6 TWR seems to be the sweet spot with FAR and a good aerodynamic shape. If you throw more thrust at it, you'll certainly get there a lot faster, but you will definitely end up with a less efficient launch. I can confirm the numbers you're seeing in the thread though. I usually budget about 3900dV to get to 100km orbit these days, and it's often less than that.

[Amaroq]

TeeGee, for a straight rocket lift, my FAR launches tend to run as:

Max thrust from launchpad to terminal velocity (usually around 105 m/s, as I'm in thick atmosphere)

Throttle down to a TWR-Throttle of 1.2 according to Kerbal Engineer Redux (in practice, I rattle between 1.15 and 1.25)

Initiate very gentle gravity turn - I'm still below 1,000m, so maybe 5 degrees off the bat, but the turn will continue as I keep gaining altitude.

Once at or around 10,000m, throttle up, usually to max, which is around 1.6-1.7 TWR for my lift stage.

With FAR, the issues are -- too much throttle too early gives you tremendous drag due to the thickness of atmosphere, and any non-gentle turn gives you side-forces that exceed the capacity of your winglets, gimbals, and reaction wheels to counter. So, "slow and gentle" is the approach.

Of course, by the time you're up around 50km, you're aimed at the horizon and at full throttle, just like a stock launch .. its just a different technique in the 0-40km range.

[TeeGee]

TeeGee, for a straight rocket lift, my FAR launches tend to run as:

Max thrust from launchpad to terminal velocity (usually around 105 m/s, as I'm in thick atmosphere)

Throttle down to a TWR-Throttle of 1.2 according to Kerbal Engineer Redux (in practice, I rattle between 1.15 and 1.25)

Initiate very gentle gravity turn - I'm still below 1,000m, so maybe 5 degrees off the bat, but the turn will continue as I keep gaining altitude.

Once at or around 10,000m, throttle up, usually to max, which is around 1.6-1.7 TWR for my lift stage.

With FAR, the issues are -- too much throttle too early gives you tremendous drag due to the thickness of atmosphere, and any non-gentle turn gives you side-forces that exceed the capacity of your winglets, gimbals, and reaction wheels to counter. So, "slow and gentle" is the approach.

Of course, by the time you're up around 50km, you're aimed at the horizon and at full throttle, just like a stock launch .. its just a different technique in the 0-40km range.

Awesome. Ya see, FERRAM is teaching me things about aerodynamics.

Before, I had built a heavy lift VSSTO (vertical ssto) launcher that pushed 65 tons into orbit with only turbojets. I had an ascent profile similar to that and was able to push stupid amounts of weight and have precise control over everything with only reaction wheels... it felt sooo cheap and gimmicky and rendered the game useless after that.

BTW that is the kind of game STOCK KSP is..if u know how to manipulate it, you can build the most ridiculous things that shouldn't fly, and achieve ANYTHING without limitation.

Reality has more obstacles than just thrust, delta v and reaction wheels. I wanted a challenge that hones my design expertise and build a plausible craft that could work on some level here in reality. If this mod didn't exist, I never would have understood the ascent profiles of real rockets and the reason they are done that way.

The only thing I need to perfect is how to read the FERRAM charts when I am designing a craft, I don't know what I need to do to get all of those values in the green.

[ferram4]

So many posts! Argh!

@White Owl: Unfortunately, that feature was removed since it turned out to be kind of inaccurate. I've generally found that deflections above 10-15 degrees cause stalling for pitch canards (depending on the overall AoA of the plane), that 15-20 degrees is generally good for ailerons, and elevators can get away with anywhere from 25-30 degrees. I've been trying to find a way to get the feature back in in a useful form, but I haven't figured that out quite yet.

@TeeGee: For the Plane-with-SAS-wobbling question, that's due to how SAS functions with high control authority and some issues with how FAR handles the control surfaces currently. I've got a sort-of fix in the experimental, but I don't know how well that works at the same velocities.

@Amaroq: What in God's name are you launching that gets a terminal V of 105 m/s? I think the worst I've ever seen is 215 m/s on the pad, and often it's much higher than that.

[B787_300]

ferram i think he might have RSS...

also the experimental what exactly is new in it?

[ferram4]

Changelog, not integrated into first page because it isn't a full release yet.

[Bobnova]

Super happy that the massive surface area bug has been fixed. It's been causing issues for me. I'm going to take the experimental FAR build for a spin now

Thanks for making this awesome mod! I really, really, really like it.

My rockets take ~3300m/s of dV to get to orbit. These are very rocket shaped rockets, with fairings. I made small (1.25m) and large (2.5m) test rockets with ~3340dV, in orbit they had ~10-35dV left on a few tries.

(I should say took, as now I've installed RSS and it takes rather more than that )

[SSSPutnik]

@Ferram- tried the experimental build on that problematic part.

Good news, it drags a lot less than before, it still drags a lot but the craft flies a lot better. It still drags a lot but is improved. Thanks.

[mrskwid]

so i won't to get a plane to fly on duna getting it there isn't the problem but the last time i tried to build one it just did't go very well.

i won't to know if anybody know's of how much wing span and power i would need for a given wight and air pressure.

any help would bee great thanks.

[White Owl]

@White Owl: Unfortunately, that feature was removed since it turned out to be kind of inaccurate. I've generally found that deflections above 10-15 degrees cause stalling for pitch canards (depending on the overall AoA of the plane), that 15-20 degrees is generally good for ailerons, and elevators can get away with anywhere from 25-30 degrees. I've been trying to find a way to get the feature back in in a useful form, but I haven't figured that out quite yet.

Yeah, I knew about the inaccuracies but still liked using it to kinda ballpark the appropriate deflection. No worries, though. It isn't actually necessary; I was just a little confused.

This is still the only mod I consider absolutely essential to doing anything in KSP.

[Orionkermin]

Hello, I'm trying to set up a custom drag model for a command pod I've made. It uses two attach nodes on the bottom so that two different shrouds can be spawned depending on the player's need. Unfortunately this means the pod tends to want to reenter nose first. If someone could help me understand what the different values mean and how they translate into the game I would be hugely grateful.

BTW I love the mod, I have a hard time playing without it anymore.

[DaMichel]

so i won't to get a plane to fly on duna getting it there isn't the problem but the last time i tried to build one it just did't go very well.

i won't to know if anybody know's of how much wing span and power i would need for a given wight and air pressure.

any help would bee great thanks.

These can fly on Duna. The big one is 5t and the smaller ones about 2.5t. The prop doesn't generate that much power. Probably about 20kN on Duna. No idea about wing parameters. I just eyeballed them and it worked.

http://i.imgur.com/ibpr1yl.jpg

http://i.imgur.com/NZia1Ye.jpg

Landing is still a problem though. They easily get thrown around in random directions upon ground contact.

[MAKC]

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Couldn't break Mach 1.1 with what is basically a flying Sears-Haack body. 40 kN on the wings alone, which is almost half the J79's thrust.

Ignore the last image. It's an F-104 I'm working on.

Edit: Didn't even notice the J79 was over-thrusting. That makes this worse actually. Max thrust is supposed to be 85 kN. FAR or AJE?

Edited March 20, 2014 by MAKC