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

[Camacha]

Is anybody looking at getting MechJeb to notice when FAR is installed and adjust itself to work with the changed aerodynamics? If not I might have a poke at it sometime since it's been irritating me lately.

I am not interested in MechJeb, but I am interested in other mods detecting and compensating for FAR. Most calculatory tools do not make sense with FAR installed.

[jrandom]

Anyone happen to know what the to-orbit delta-v for Eve is with F.A.R.? Kerbin is around 3200m/s - 3500m/s, but I can't find any stats for Eve.

[ferram4]

I'm gonna go and do some general guessing trying to come up with the dV to get to orbit from Eve's surface, though don't trust my numbers too much.

Based off of the numbers on the wiki, for a circular orbit at 100km (just above the upper reaches of Eve's atmosphere) you need to be going 3196 m/s.

Then we need to think about gravity losses; getting off of Kerbin and getting up to 70km incurs a 1000 m/s gravity loss; Eve's surface gravity is 1.6g and we have to go higher, so let's guess ~1800 m/s lost to gravity.

Now we deal with drag losses. On Kerbin, this is somewhere between 50 - 500 m/s, depending on the vehicle design. On Eve, we'd have to go faster to get to orbit, spend more time in the atmosphere, and the atmosphere is 5 times thicker. So let's guess 5 times the drag losses, so 250 - 2500 m/s.

So all of this guesstimating leaves us with ~5250 - 7500 m/s to orbit. That's a pretty big range, all things considered, but it's not that bad, especially since the last 2000 m/s can be handled with a nuclear engine and drop tanks.

So I'd first try dropping a small probe there with a launch system with 7500 m/s atmospheric and an Eve TWR of 1.5 and see if it can get to orbit. Based on that, you have the data for your manned mission. Keep in mind that you will have to try and design a vehicle that will be able to remain stable during reentry but will be stable during the return flight as well; I would advise adding some type of aerodynamic extensions to the bottom and top of the rocket to try and invert its stability characteristics for the initial landing and jettison them just prior to touchdown.

[jrandom]

Because of the hard-mode rules I play under, no unmanned probes, sadly -- I don't fly any until RemoteTech 2 is done... OH WAIT I HAVE PROGCOM!

Time to build that fully-programmed-and-automated mission I've been thinking about! Yay! Gonna take forever just to get the darned thing to fly, but it'll be all sorts of nerd-fun! A great next step since I just finished up my Moho landings.

[loknar]

Good plan.

I just fixed my installation and just started an Eve mission with not much planning or research.

I re-use my mars mission transport to send a spaceplane and station to Eve. Eve is a huge challenge. My spaceplane can each orbit with no air from Kerban. I guesstimate it can do a 30km flyby on Eve.

But first I have to aerobrake my fast-approaching mission cluster-ship. Very unlikely to succeed. I already tried at 65km but not enough braking and too much flames.

[jrandom]

I'm too impatient... Even though I'm reading my way through the ProgCom docs, I've decided to try a manned landing/return Eve mission and have a good chunk of the lander/return vehicle prototype slapped together. This will be... interesting.

[SPANNERTEHCAT]

FAR is making my rockets flip and I don't know why, im using the KW rocketry fairings around a payload and B9 aerospace small wings with the mechjeb ascent autopilot set to put me up at 70 KM and to start the turn at 10 KM at a 60 % angle but when the turn starts the rocket loses all control and turns upside down.

I have tried to manually slow down the turn but no matter what it just flips out.

my SSTO's fly fine.

[jrandom]

FAR is making my rockets flip and I don't know why, im using the KW rocketry fairings around a payload and B9 aerospace small wings with the mechjeb ascent autopilot set to put me up at 70 KM and to start the turn at 10 KM at a 60 % angle but when the turn starts the rocket loses all control and turns upside down.

I have tried to manually slow down the turn but no matter what it just flips out.

my SSTO's fly fine.

I'd hazard a guess that the rocket is bottom-heavy, putting the center of lift above it. This will make the rocket highly prone to flipping while in an atmosphere.

[jrandom]

So all of this guesstimating leaves us with ~5250 - 7500 m/s to orbit. That's a pretty big range, all things considered, but it's not that bad, especially since the last 2000 m/s can be handled with a nuclear engine and drop tanks.

The best I've been able to hit so far is 8837m/s, but that's all vacuum numbers. I'm going to have to manually add up the atmospheric numbers for the lower stages and see if I still get a good answer. Still, not bad for my third design attempt. Still going to see if I can find a better way to construct this monster.

Edited September 17, 2013 by jrandom

[Van Disaster]

FAR is making my rockets flip and I don't know why, im using the KW rocketry fairings around a payload and B9 aerospace small wings with the mechjeb ascent autopilot set to put me up at 70 KM and to start the turn at 10 KM at a 60 % angle but when the turn starts the rocket loses all control and turns upside down.

I have tried to manually slow down the turn but no matter what it just flips out.

my SSTO's fly fine.

They're flipping because you're turning 30 degrees all at once, going almost supersonic I'd imagine; don't do that, the prograde marker ring is a good thing to use as a target for where to point the rocket ( keep it's direction inside the ring - this is not so important when the rocket isn't moving fast however if you manage it all the way up, congrats you just did a real gravity turn ). Start turning *at the pad*.. 1km alt at most. If you're still flipping out then you need fins of some sort, your rocket is overly draggy at it's nose.

I use MJ settings of 0.3-70, and 35-55% profile depending on the rocket's TWR. Usually aim to drop the first stage at 25km or so when the air is getting thin enough for a lower TWR motor to be enough. Launch TWR of 1.3 as a working minimum; you can go lower, but I find that just wastes fuel & I attach some short-burn SRBs to get the thing off the pad & moving.

[lipatden]

FAR is making my rockets flip and I don't know why, im using the KW rocketry fairings

Try putting small aerodynamic surfaces (fins, canards) at the base of your rocket, this helps counteract the aerodynamic forces on the fairing, helping you maintain a reasonable angle of attack. MJ will get a bit confused that it can't turn as fast as it would like, but that's a good thing - it has no idea how dangerous it is to throw a rocket sideways into a slipstream when one end has significantly higher drag and the other is where all the weight is - basically what Van Disaster said...

[KerbMav]

I'm going to have to manually add up the atmospheric numbers for the lower stages and see if I still get a good answer.

Do you? Does un-compacting the window, clicking on Eve and selection atmospheric not give good estimates?

[jrandom]

Do you? Does un-compacting the window, clicking on Eve and selection atmospheric not give good estimates?

It does, but the numbers for the upper stages won't be correct. So I'll have to guess which stages will be atmosphere, add those up, then switch to vacuum and add up the rest of the stages.

[KerbMav]

Kerbit! You are right ...

[Ratzap]

Does anyone know a decent pack with small fins for rockets? I mean 0.625 and 1.25m stuff - the canards, tailplanes and winglets are just too damn big for those. It looks stupid and wastes space. I'm just looking for some good old fashioned *small* stabilizers to slap on the tail of my rockets to they don't tip n flip so much. They probably wouldn't even need to have control surfaces since you mostly just want them there to shift the CoL down.

[NathanKell]

pWings, of course.

But if you want premade, try TV PP. Although there aren't any flying stabs of smaller than AV-R8 size, there are .5m control surfaces, mini winglets, etc.

[Ratzap]

pWings, of course.

But if you want premade, try TV PP. Although there aren't any flying stabs of smaller than AV-R8 size, there are .5m control surfaces, mini winglets, etc.

Yeah I have the TV PP pack but those are still 1 or 1.5m x 0.5. The control surfaces, hmm, I wouldn't have though of just wacking one of those on the side of a tank. Worth a go I suppose. But hey, 3d types, here's a niche (albeit rather small) to occupy - 1.25 and smaller aero parts. Nuke has a couple of bits but it's still hard to scrape enough together to build small things.

[NathanKell]

No, the TVPP wingtips are like .6m! I used those before I went all-pWings.

[Ratzap]

Ah thanks, I found it. Snuggled at the bottom of the screen next to a huge wing. That should do the trick.

[NathanKell]

Ah, excellent!

[Senshi]

The general rule is: If you need wings/canards on your rocket, your design is flawed. They add drag and weight for little benefit, which usually could be solved "properly" by improving rocket layout.

It's only for VERY asymetrical payloads that I would even consider using them. On the other hand asymetrical payload is a flaw as well, so I never have those either...if the vessel needs to be asymetrical, it gets sent up in parts and assembled in space...

[Ratzap]

Or you're not trying to launch really small simple rockets with FAR on. There is no design to be flawed, they're only 3 or 4 parts. If you want to do a gravity turn at any altitude low enough to save a bit of fuel, you will need something. Wheels cost more mass than the entire payload so a couple of wings in the right place with a gimballed engine and all is good.

You do know you're posting in the FAR thread right? Things tip over under 33km or so real easy, asymmetrical simply isn't worth wasting time trying.

[Diazo]

That is a very sweeping statement.

I've got a rover built around a big kethane tank I want to loft. Due to the wheels needing clearance, the center of mass of the rover is well off center when I start building a rocket around it.

This also makes a very nose-heavy rocket. In theory if I do the gravity turn correctly I will not have stability problems, but getting into things like this mean you have a very small margin of error during the launch.

So I put wings/canards on to increase my margin of error so I don't send my rocket into the ground because my launch profile was off by a couple degrees.

I could go back and spend 4 or 5 more launches tweaking the rocket instead, but I'd rather put the wings on and get my rover to the Mun and start mining.

D.

[SPANNERTEHCAT]

They're flipping because you're turning 30 degrees all at once, going almost supersonic I'd imagine; don't do that, the prograde marker ring is a good thing to use as a target for where to point the rocket ( keep it's direction inside the ring - this is not so important when the rocket isn't moving fast however if you manage it all the way up, congrats you just did a real gravity turn ). Start turning *at the pad*.. 1km alt at most. If you're still flipping out then you need fins of some sort, your rocket is overly draggy at it's nose.

I use MJ settings of 0.3-70, and 35-55% profile depending on the rocket's TWR. Usually aim to drop the first stage at 25km or so when the air is getting thin enough for a lower TWR motor to be enough. Launch TWR of 1.3 as a working minimum; you can go lower, but I find that just wastes fuel & I attach some short-burn SRBs to get the thing off the pad & moving.

thanks, I will trial and error with higher angles and lower turn start times with each station module until it works

cheat parts are always an option

[tzink]

I'm really new so I'm pretty sure I'm doing something stupid, but I can' figure out how to get the GUI to show up for FAR... Should it just be there automatically? Or do you have to press something?