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

[NoClass]

It "feels" like aircraft take a very long time to slow down to glide speeds after the engine is cut, even with spoilers and speed brakes.

I don't have any of my documentation in front of me so I am shooting from memory. But the F-16C can glide 15km for every 1000ft AGL.

Dead stick engine out landing in an F-16. Take note of his air speed on the left side of the HUD.

And after all, the pilot did dump all his fuel in which i did not.

That's some good info!

I had a long winded post explaining that the problem isn't so much with glide ratio, which seems right on, but that craft seem to hold onto their energy for waaay too long. In that video, our brave Viper driver flares about 10 seconds before touchdown, and kills about 75 kts of speed in that frame of time. (~ 215 to 150 kts, or ~105 to 75 m/s). I couldn't get even wide-winged planes to slow down that fast.

...then I dumped fuel (TAC fuel balancer). That's the missing piece.

KSP parts tend to be a bit more dense than in the real world to begin with, so an aircraft full of gas will take a lot longer to slow down to max glide speed.

TL,DR; Dumping a couple of tons of gas will radically change how quickly your craft slows.

Edited July 27, 2014 by NoClass
yeah, I'm just a knucklehead

[brusura]

I have got some weird gui flickering, looking into the log pointend to far:

in ksp.log

ArgumentException: Value does not fall within the expected range.

in output_log

ArgumentException: Value does not fall within the expected range.

at ferram4.FARControlSys.OnDestroy () [0x00000] in <filename unknown>:0

at ferram4.FARControlSys.OnGUI () [0x00000] in <filename unknown>:0

at (wrapper delegate-invoke) Callback:invoke_void__this__ ()

at (wrapper delegate-invoke) Callback:invoke_void__this__ ()

at RenderingManager.OnGUI () [0x00000] in <filename unknown>:0

(Filename: Line: -1)

can you check these files?

https://www.dropbox.com/s/sfjpobtb5epi1wf/KSP.zip

Edited July 27, 2014 by brusura

[guitarxe]

Longer rockets are good, yes, but only if they concentrate the CoM near the top (for reference, I just got this easily into orbit - a 3.75m Expanded payload on top of a 2.5m stack). Your CoM is fairly low down and near the CoT which will make it unstable. Quick question - what is inside the fairing? And how big is this main stack? I think that's a KWR 2.5m engine on the bottom which means the RCS ports (which add to the drag at the top) are the right size, but the radial decouplers are pretty big, bigger than stock.. the scale of things is confusing me. I think, and I could be wrong here, but your CoD is too high up as well.. as I said, put some fins on the bottom and if possible, shield those RCS ports.

Here's what's inside the fairing

https://i.imgur.com/DMDgyLP.jpg

The stack decoupler there is stock TR-18A, if you were looking for a size reference.

Here's the size of the procedural fuel tank beneath the payload

https://i.imgur.com/xgxaXRK.jpg

The engine is the stock LV-T30

And here's the procedural boosters on the side

https://i.imgur.com/uVD8CV1.jpg

At this point I really only care how should I build a rocket to deliver a payload of only 1,171kg into orbit? Because adding fuel tanks and engines puts the COM down below the center point of the rocket, because the payload is so light.

[Hodo]

Yes it does. As long as the wing part itself moves via an IR hinge, it's not some animation of a part and the part stays still (like D12 swing wings).

No those wings are moved with IR rotation points. I wanted to do a more stable screw setup like the real F-111 and Mig-23 but would need to place a few small attachment points to attach the piston to and then to the wing, and then attach the free moving docking washer to the other end to get it to move with more support. The current design is limited to about 6Gs at subsonic flight, much more than that it will pull the wings apart.

That's some good info!

I had a long winded post explaining that the problem isn't so much with glide ratio, which seems right on, but that craft seem to hold onto their energy for waaay too long. In that video, our brave Viper driver flares about 10 seconds before touchdown, and kills about 75 kts of speed in that frame of time. (~ 215 to 150 kts, or ~105 to 75 m/s). I couldn't get even wide-winged planes to slow down that fast.

...then I dumped fuel (TAC fuel balancer). That's the missing piece.

KSP parts tend to be a bit more dense than in the real world to begin with, so an aircraft full of gas will take a lot longer to slow down to max glide speed.

TL,DR; Dumping a couple of tons of gas will radically change how quickly your craft slows.

You have to remember the F-16 has leading edge slats and flaps and a VERY effective air brake.

I hadn't try to build an aircraft like the F-16 because of its small size. Perhaps I might toy with the concept a bit in my RO install but I am only just now getting to understand where and how to place slats on the leading edge of the wings.

Edited July 27, 2014 by Hodo

[Renegrade]

Perhaps I might toy with the concept a bit in my RO install but I am only just now getting to understand where and how to place slats on the leading edge of the wings.

Well, if you find out anything useful, please share. Anything that lets me float around and land slowly is good for my Science!â„¢ Plane. I'm hoping to one day be able to land it even on a Mountain biome...

[Hodo]

Well, if you find out anything useful, please share. Anything that lets me float around and land slowly is good for my Science!â„¢ Plane. I'm hoping to one day be able to land it even on a Mountain biome...

I built a Cessna that takes off and lands at a REALLY slow speed in my RO install, I will check it tonight, but I think it is sub 50m/s.

The other option is to make a VTOL. The Osprey is a great design for that job.

Edited July 27, 2014 by Hodo

[softweir]

*** snip ***

Where are you sending that?! The first two stages have somewhat more dV than you need to get to orbit - you could get away with a lot less fuel for that. Also try to shrink the fairings to be only *just* big enough to cover your payload, and make the payload as small as possible. It would help to see a picture of your payload so we can comment on that.

Another thing to check is that your payload is actually properly enclosed. A few people have reported incidents when fairings don't properly enclose payloads - try taking the fairings off, make sure symmetry is turned on, then replace them.

[Renegrade]

I built a Cessna that takes off and lands at a REALLY slow speed in my RO install, I will check it tonight, but I think it is sub 50m/s.

Sub-50 would be sweet, I'm down to just above 50 on my four wing science plane (I've actually landed at 45 but that was more like 'crashing gently on the wheels' than landing). I figure a 45-ish landing would let me land in even rough highlands or maybe even take a stab at that angled plateau in the mountains west of KSC.

I've got Firespitter, SXT, KAX, (and maybe Pizza and Aerospace?) installed right now and progressing through a FAR-enabled, 6x career tree. Air/space planes will definitely help control costs

The other option is to make a VTOL. The Osprey is a great design for that job.

I tried making a VTOL once, it didn't work out too well (lack of tools). I might give that another shot with the enhanced tools I have now, might work better..

[Hodo]

Sub-50 would be sweet, I'm down to just above 50 on my four wing science plane (I've actually landed at 45 but that was more like 'crashing gently on the wheels' than landing). I figure a 45-ish landing would let me land in even rough highlands or maybe even take a stab at that angled plateau in the mountains west of KSC.

I've got Firespitter, SXT, KAX, (and maybe Pizza and Aerospace?) installed right now and progressing through a FAR-enabled, 6x career tree. Air/space planes will definitely help control costs

I tried making a VTOL once, it didn't work out too well (lack of tools). I might give that another shot with the enhanced tools I have now, might work better..

I would suggest one other mod to help out, Procedural Wings.

But you have Firespitter so you have some basic VTOL engines. The trick is placing them in the vertical mode first and placing the CoT through the center of the CoM. The next task is to make sure the CoM does not move as the fuel drains out of the craft. This means placing the fuel tank(s) in the center of the CoM. The last thing is getting the airbrakes setup so you can slow down to transition from horizontal flight to vertical flight. This is the hardest thing to do, because as the craft loses lift it may stall one side or the other, so I like to place RCS thrusters to help balance out the craft in Vertical mode.

I haven't built a serrious VTOL in my RO install but I have built a few dozen in my regular install. The last one I have built works quite well with or without SAS on.

But I have been taking this time I am at work to read and study a bit on leading edge wing slats and flaps. Trying to get my head wrapped around the concept and the idea, I have some ideas that I plan on testing out later when I get home. Most of my testing is done in my .23.5 install of Realism Overhaul because I know everything works in there currently. If I get the idea working there I can easily translate it to .24.2 KSP.

[NathanKell]

Sub-50 would be sweet, I'm down to just above 50 on my four wing science plane (I've actually landed at 45 but that was more like 'crashing gently on the wheels' than landing). I figure a 45-ish landing would let me land in even rough highlands or maybe even take a stab at that angled plateau in the mountains west of KSC.

If I remade it now I'd use the SXT prop engine.

It stalls at about 35-40mph.

[Renegrade]

I would suggest one other mod to help out, Procedural Wings.

I've tried PWings out in the past but they're a bit fussy to work with, and they didn't seem to generate much lift for their size. I might give 'em another go to see if any of that's changed once I get to the aircraft stage here..

But you have Firespitter so you have some basic VTOL engines.

My 'Flight' install does. Plus the others. VSTOL or simply STOL would be good for my needs though

The trick is placing them in the vertical mode first and placing the CoT through the center of the CoM. The next task is to make sure the CoM does not move as the fuel drains out of the craft. This means placing the fuel tank(s) in the center of the CoM. The last thing is getting the airbrakes setup so you can slow down to transition from horizontal flight to vertical flight. This is the hardest thing to do, because as the craft loses lift it may stall one side or the other, so I like to place RCS thrusters to help balance out the craft in Vertical mode.

I'm good with the CoT handling, and fairly good with fuel balance (the science planes and light test planes I build only have slight movement of the CoM from full to empty). Airbrakes are something of an 'in progress' thing for me now (along with proper flaps and spoilers 'n' all). As for the transition, yeah, I've noticed that with some of my slow-landing experimentals... gentle, docile handling, stalling, stalling... and then suddenly BAM, deep stall and falling off to the right or left.

One of the RC planes I had, had this twist in the wing to combat that sort of violent sudden roll.. I think the tips of the wings were rotated...downwards? Perhaps something like that would help too?

But I have been taking this time I am at work to read and study a bit on leading edge wing slats and flaps. Trying to get my head wrapped around the concept and the idea, I have some ideas that I plan on testing out later when I get home. Most of my testing is done in my .23.5 install of Realism Overhaul because I know everything works in there currently. If I get the idea working there I can easily translate it to .24.2 KSP.

Once I get my career rolling in the "Flight" install, I'll be trying out leading edge slats as well. I think I've got a reasonable flap setup in my stock-ish install for regular un-crazy planes, as well as a setup for a four-wing plane (hehe). I find assigning flaps on the elevators at the same time helps auto-trim the plane a bit..

http://i.imgur.com/kf8gOFpl.jpg

If I remade it now I'd use the SXT prop engine.

It stalls at about 35-40mph.

Sweet Kraken in space! that's like.. 17 m/sec according to Google's suggestion! Nice! That's even slower than my stock aero planes!

[Hodo]

http://i.imgur.com/kf8gOFpl.jpg

If I remade it now I'd use the SXT prop engine.

It stalls at about 35-40mph.

NathanKell where is that cockpit from?

@ Renegrade

PWings is no less fussy about lift then anything stock, if anything some of the stock wings are a bit overpowered for their size.

Having the wingtips slightly downwards is great for several things, there is a nice write up about the benefits of each of the various placement of wings in the tutorials section.

The otherthing you could do to help lower your landing speed is increasing the AoA of your wings in relation to the craft.

Edited July 27, 2014 by Hodo

[DaMichel]

@Renegade: I made some slow flying planes for the Duna challenge. The slowest level flight i managed was just above 21 m/s. But that thing basically consisted only of wings

Here is the full album. http://imgur.com/a/hEEOj VTOL crafts are very nice for exploration. I made a couple of these, too (check sig). They can be very hard or relatively easy to fly depending on how well they are balanced and how much RCS/torque wheels you stick on them

Edit: P.S. B9 has RCS thrusters which run on air, so they don't need any fuel. Very useful for VTOLs!

Edited July 27, 2014 by DaMichel

[Renegrade]

NathanKell where is that cockpit from?

He'll have to answer to be sure, but it looks like the SXT cockpit. The 0.625 Bonny. It's very small.

Having the wingtips slightly downwards is great for several things, there is a nice write up about the benefits of each of the various placement of wings in the tutorials section.

Is that um the large image-based one? I've been over that already, I knew most of it already I'm not 100% convinced all of it applies to FAR...

The otherthing you could do to help lower your landing speed is increasing the AoA of your wings in relation to the craft.

Hmm, I haven't tried that. I'll give that a go this time 'round. That shouldn't have too much of a negative effect..should it?

Having a higher AoA on the leading wings would probably be beneficial actually, if they stall first and the tail remains in flight, will naturally bring the nose down...

@Renegade: I made some slow flying planes for the Duna challenge. The slowest level flight i managed was just above 21 m/s. But that thing basically consisted only of wings

http://i.imgur.com/TTOT5AC.jpg

Neat looking ultra-light there I've seen that Duna challenge before but was busy exploring other mods at the time. Maybe I'll give it a go

Edit: P.S. B9 has RCS thrusters which run on air, so they don't need any fuel. Very useful for VTOLs!

Sorta like um, vectored outlets from the engine sort of dealy then? Neat!

[Wedgenet]

Here's what's inside the fairing

At this point I really only care how should I build a rocket to deliver a payload of only 1,171kg into orbit? Because adding fuel tanks and engines puts the COM down below the center point of the rocket, because the payload is so light.

That's okay. The center of mass doesn't need to be in the center of the rocket.

As others have said, what you really need are some fins in the back of the rocket. Think about how a dart flies through the air when you throw it at a dart board. The fins in the back of the dart stabilize it as it flies through the air.

Rockets have fins so they don't flip.

Here is a picture of a German V2. Your rocket needs some fins.

http://www.warhistoryonline.com/wp-content/uploads/2013/09/4609-050-33F555A7.jpg

[Hodo]

Here's what's inside the fairing

https://i.imgur.com/DMDgyLP.jpg

The stack decoupler there is stock TR-18A, if you were looking for a size reference.

Here's the size of the procedural fuel tank beneath the payload

https://i.imgur.com/xgxaXRK.jpg

The engine is the stock LV-T30

And here's the procedural boosters on the side

https://i.imgur.com/uVD8CV1.jpg

At this point I really only care how should I build a rocket to deliver a payload of only 1,171kg into orbit? Because adding fuel tanks and engines puts the COM down below the center point of the rocket, because the payload is so light.

Javascript is disabled. View full album

This is what I use in my RO install to get things to space. I use a variant of it now, that is a bit wider and hauls 10 tons into an orbit around RSS Earth. It is a Solid booster first stage, with a burn time of 150seconds. Note the TWR on the craft is less 1.4:1, in this picture it has a light cargo in the top, I think it was only 1 ton, so it had a higher than nominal TWR.

Also notice how it is not short and fat. How many short fat objects do you see getting launched into space? How many short fat darts do you see? Just because you have a wide cargo, doesn't mean you have to have a 9mm Parabellum round for a rocket.

[Renegrade]

At this point I really only care how should I build a rocket to deliver a payload of only 1,171kg into orbit? Because adding fuel tanks and engines puts the COM down below the center point of the rocket, because the payload is so light.

Here's my take on a 2T launcher:

Using stock parts+procedural fairings, designed for a stock world + FAR. The payload is the 2.25t fuel tank, with the 1.25m rcs tank and batteries and a probe core (simulating a very small re-fuel mission). It also works with a 2.5m diameter payload (I tested), same geometry on the fins. Please forgive the crappy orbit, I wasn't paying full attention during the last bit and overshot the AP :/

Note that serial staging is both easier to handle aerodynamically and cheaper. The TR-18A is like.. 3/4 of the price(isH) of the TT-38K radial and like half the price of the TT-70, and you only need one. If you're playing campaign anyhow.

Also note that piloting in FAR is a bit different than stock, it's unforgiving of sudden turns

By the way, what's the solar panel on that satellite? It looks cool

[Motokid600]

Having strange behavior on depleted serial stages. I've seen there's a bug going around that's causing torque on depleted radial stages and destroying the center. I'm not sure if this is the bug I'm experiencing because my radial tank separate cleanly with sepatrons. ( although on my last launch I looked back and saw the tanks spinning so hard the engines ripped off. ) But my problem is depleted serial stages that kick upward violently when separated. If not for double plane sep my third stage would be broken off. But the rocket still gets a hard kick.

Then afterwards the stage is doing somersaults end over end as if all the tank itself has no weight to it.

[softweir]

If you are getting spinning on detached stages then that is most likely due to clipping issues. Somewhere, you have two parts that are too close together. Try rebuilding the stage, especially paying attention to symmetry-mounted parts such as winglets and engines on 1-n adapters. I had problems with one design where I had put 4 engines at the bottom of a 1-4 adapter, and somehow they were clipping - I had to take them off and rotate them a bit before that design would fly.

Good luck!

[steve_v]

I have got some weird gui flickering, looking into the log pointend to far:

in ksp.log

ArgumentException: Value does not fall within the expected range.

in output_log

ArgumentException: Value does not fall within the expected range.

at ferram4.FARControlSys.OnDestroy () [0x00000] in <filename unknown>:0

at ferram4.FARControlSys.OnGUI () [0x00000] in <filename unknown>:0

at (wrapper delegate-invoke) Callback:invoke_void__this__ ()

at (wrapper delegate-invoke) Callback:invoke_void__this__ ()

at RenderingManager.OnGUI () [0x00000] in <filename unknown>:0

(Filename: Line: -1)

can you check these files?

https://www.dropbox.com/s/sfjpobtb5epi1wf/KSP.zip

You are not alone :-(

Just had the same issue (and spaming exactly the same errors) re-entering a simple spent stage - KWR engine & tank, stock large SAS, 2 batteries & a mechjeb.

No problems on the way up, so I'm somewhat stumped as to what could be causing this.

Running a fairly extensive list of mods, so any clues as to where to start looking much appreciated.

EDIT: Hmm, happens outside atmo too so probably not FAR.

Edited July 28, 2014 by steve_v

[Motokid600]

Thanks for the reply softweir, but it's just a simple engine-tank-decoupler giving me the problem. I've since tried resetting them. The depleted stage behaves as if it's CoM is down below the engines.

[NoClass]

Thanks for the reply softweir, but it's just a simple engine-tank-decoupler giving me the problem. I've since tried resetting them. The depleted stage behaves as if it's CoM is down below the engines.

I've been able to get the BACCs boosters to properly separate with a couple of seperatrons mounted to the top of each. That never used to be necessary, of course, but it functions as a workaround.

Edited July 28, 2014 by NoClass
talking about two different things.

[ferram4]

While it's great that those bug reports included logs, you didn't provide reproduction steps. I mean, it's great to know something's wrong, but if no one tells me how to make it go wrong then I won't be able to fix it.

[tetryds]

Here is a <30m/s ultralight

Uses KAX and Pwings

You will want to stay between 25 and 30m/s if you are not going to land.

Download: https://www.dropbox.com/s/pskrei79nljckxw/Roaken%20Ultralight%20Mono.craft

Edited July 28, 2014 by tetryds

[steve_v]

While it's great that those bug reports included logs, you didn't provide reproduction steps. I mean, it's great to know something's wrong, but if no one tells me how to make it go wrong then I won't be able to fix it.

If you're meaning me...

In my case it's pretty straight forward:

Launch a multi (in this case 3) stage rocket.

Seperate final stage from payload once in stable ~100km orbit.

Switch to decoupled stage.

The UI flickering starts shortly after switching vessels.

So far it's repeatable for me, at least as far as the same ascent stages with 3 different payloads.

Just started in on 0.24 so I haven't had a chance to test any other designs yet.

Goes without saying I can't speak for brusura

Edited July 28, 2014 by steve_v