Thinking about making the switch to FAR.

[Alshain]

One tip I have for FAR: start by making conventional planes, with separate wings and tailplane. You can certainly make a spaceplane that way. Tailless delta aircraft, ie looking like Concorde, are much more difficult to make fly well.

This is true. Elevons are not as easy to work with as Elevators and Ailerons in FAR. They do work, but they are more challenging.

[ratchet freak]

Also if you put the CoL far behind the CoM for a atmospheric plane then angle the horizontal stabilizer down a bit (so they provide negative lift)

This means that when the plane speeds up it will pitch up and when it slows down it will pitch down. So it will self stabilize a bit.

[cantab]

Indeed. More generally, look at where the yellow CoM line crosses the axis in the static graph. That's the angle the plane will fly at without any pitch or pitch trim input. It can be nice for it to be an angle where you get non-zero lift. But keep in mind how things shift around at different Mach numbers.

[capi3101]

Alright y'all, thanks for your answers to my questions. I think I'll give it a go - if I don't like it, I should just be able to delete the directory and enjoy a few more weeks (hours, minutes, whatever) in the soup.

Forum admins - I'd like to keep this thread open in perpetuity to whoever has questions regarding difference from stock to FAR. I don't know how long that will remain an issue given the upcoming change to the stock model, but I imagine folks in the future might need to ask their own questions and make their own judgments about which system to utilize. I myself might have some more questions on the matter a year from now - who knows...

[eddiew]

...I think I'll give it a go - if I don't like it, I should just be able to delete the directory and enjoy a few more weeks (hours, minutes, whatever) in the soup...

Good stuff! There's really no reason not to like FAR. The usual gripe is that things fall apart, but there's an option in the menu to turn this off if it's annoying you. You'd be surprised what you can fly under FAR when it's been told not to rip your wings off

[capi3101]

Alright - last night I made the switch from the souposphere to the......FARscape? What the hell do y'all call that anyways?

So I figured I'd start out small - got into the litterbox and built a simple single-Turbojet RGU-controlled plane. Put a batt with the probe core, put a nose cone on front, added a short Mk2 Adapter to that (drained the Liquid Fuel out of it along with most of the oxidizer), put a small cargo bay on. Stuck two PB-NUKs, a Stabilizer, two wheels and a girder in the bay. Added a Mk2 Liquid Fuel Tank to the end and strutted the bay to the tank, ran a fuel line from the front adapter to the fuel tank, then closed the cargo bay doors. Added a Long Mk2 Adapter to the end of that (drained the LF again, left the oxidizer intact), then added a Turbojet and four 24-77 engines. Put a couple of Engine Nacelles on the sides, bicouplers up front and Ram Intakes on those (4 Ram Intakes). Used RCS Build Aid to balance the mass; had to add a couple of RCS cylinders for ballast into the equipment bay. Delta-Deluxe Winglet for a rudder and for tail elevators, Advanced Canards up front as canards. Wings were a pair of Delta Wings, a pair of Wing Connector Bs and a pair of Swept Wing As, with Elevon 3s as ailerons. Put tricycle gears on, unlocked the steering up front and disabled the front brakes, then fired up FAR for analysis.

It was at this point that I realized I really should've RTFM. So "red is bad" - got it. What the crap do I do about it? I mean, I knew I'd built a plane that would've had absolutely no problems with the soup - 15 tonnes on the nose, 1 Turbojet, 4 Intakes with the right amount of fuel to make it up, down, fart around a bit and land. If anything at all, it wouldn't have had enough wing area to take off at a low speed - not an insurmountable problem. But I was seeing red numbers all up and down the Mach scale. In flight I realized it was telling me I'd have hellacious side-slip, because I was having some hellacious side-slip throughout the flight. Couldn't get the damn thing to hold 090 for the life of me...

Anyway - first flight attempt!! Lawn dart. No problem - go back to the SPH, adjust the wings to move the CoL closer to the CoM and adjust the position of the ballast to re-balance the plane. Second attempt - plane careened off the runway and 'sploded. Realized I was holding down the D key instead of S - so that one was "pilot error". Facepalmed. Third attempt! Tail struck. Fourth attempt! Tail struck. Fifth attempt! Wobbled up for a moment, then tail struck.

Sixth attempt I got into the air with my butt intact. So I cranked the nose up to 40 degrees and started flying. Went ahead and opened up the FAR controls. Flight was...okay-ish. Aside from the aforementioned side-slip, the damn thing consistently went into a minor stall as I approached 12k AGL, quickly evolving into a major stall. This happened twice; both times I was able to recover from the inevitable spin, get the plane pointed back in the prograde direction and lift the nose back up above the horizon, having lost nearly 6k of altitude in the process. After the second time I cranked the nose down to 20 degrees and it didn't happen again. I'm guessing I got the AoA too high there. Damn physics...

So after that I didn't have many problems. I did encounter something that folks call "SAS Waggle", but it wasn't particularly severe - the one thing y'all have been warning me about that didn't happen was the spontaneous disintegration of the plane. The jet flamed out at about 33k AGL with the craft going Mach 3.1, too low and too slow for me to switch over to the rockets - or, thinking about it this morning, my soup-trained brain thinks. Could I have made it? I dunno - I didn't try.

Anyways, that was my first experience with FAR. I wish I'd taken screenies - I still can but it'll be this evening before I'll be in a position to do so. Meanwhile I might RTFM and figure out just what exactly I was doing wrong...

[WhiteKnuckle]

The jet flamed out at about 33k AGL with the craft going Mach 3.1, too low and too slow for me to switch over to the rockets - or, thinking about it this morning, my soup-trained brain thinks. Could I have made it? I dunno - I didn't try.

That's more than high enough, but not nearly fast enough. Are you playing with B9? If so mach 3.1 is all you'll get out of a turbojet. If not then I would recommend a less steep climb over 20k so you build up more speed before the jet gives out. If you can't build up more speed, or if your speed is climbing so slowly it makes you want to kill yourself, then you either need more thrust or less drag.

[eddiew]

33km is really high for a turbojet with FAR, and not too low for rockets. Some of my early birds had to switch to rockets at 25km and still made orbit. You're right about too slow though, you don't want to go to rockets until you've maxed the air breathers at mach 5.

Rule of thumb flight checkpoints:

- mach 1+ @10km

- mach 2.2+ @20km

- mach 3.5+ @25km

- level off until mach 5

- nose up gently, say to 100m/s vertical speed (or less)

- nurse the throttle until the air is so thin you're not getting any thrust (usually about 30km)

- switch to rockets and nose up more. You want to clear the worst of the drag (< 50km) quickly, without pitching so hard you lose forward velocity. It's a balance game and each bird will fly differently here.

- at 50km aim prograde again and just tickle the rockets to keep your AP above 70 while your PE comes up to meet you

Also, check out the Kerbodyne SSTO thread, which is full of excellent FAR spaceplane designs, and Wanderfound is very helpful with getting wannabe spaceplaners up to speed

*edit* Getting a FAR to green light you at 30km is really hard. If you can pull off a board of greens at 25km at mach 3.5, then you can generally get the plane to orbit, with various degrees of fighting the stick. For your sanity, I recommend a TWR of at least 0.75 on the runway, and don't overkill on wing area. You need less than you think! Again, see Wanderfound's Kerbodyne designs, particularly the later stuff, which shows how minimal you can go. And remember to turn down wing strength to save weight; 0.6 is fine for wings, I use 0.5 for tail fins.

*edit edit* If you have B9, then turbojets are nerfed to mach 3.2. The config is easy to remove, or you can design with rapiers only, whichever you prefer.

Edited February 25, 2015 by eddiew

[Jovus]

I'll also say that 33km is actually pretty darn high for turbojets. I routinely kick the rockets on at about 22-25km (I don't mind the waste) and keep the jets on until about 28 or so to ram more air in.

At a guess, I'd also say you have too many intakes. Yes, theoretically you're able to go higher, but you're also massively increasing your drag. (And no, turning them off doesn't decrease their drag in the slightest.) Around 2 to 2.5 per jet should be enough, methinks.

The biggest thing is the ascent angle, as others have said. Get to 10km as quickly as possible with your plane. Then level off to about 5-20 degrees (depending on your acceleration) so you can hit the numbers eddiew posted.

As for your sideslip problem, there's basically one solution: a better rudder. Better either means bigger (which increases drag) or further away from your CoM (which might be difficult depending on your airframe).

Regarding tailstrikes, there are a number of possible solutions. One of my favorite is a pair of landing gear set right at the tail and elevated above the plane of the others, so that when you get enough pitch authority to lift the nose, you hit those instead of your engine.

[capi3101]

Yeah, I'm guessing my plane design was high on drag - would y'all recommend a pair of Shock Intakes over a quad of Ram Intakes for a single engine?

Not playing with B9 and I have no intention of installing it at this time. I did get Procedural Wings last night, but once again I didn't bother to read the manual, so I had no idea what I was doing and wound up going with stock wing parts on the design.

TWR at launch was 0.77, IIRC; suggests to me that the mass-to-engine guideline might carry over from stock but I'll have to experiment more. I'll try to see if my plane will hold eddie's flight profile after I tweak it a bit more. I'll also be sure to check out the Kerbodyne thread.

As far as the rudder goes, something told me I shouldn't have used a Delta-Deluxe for that purpose. It's a lousy rudder choice even in the soup. Ordinarily I'd go with an AV-R8 but I'm wondering if I shouldn't swap it out with a Standard Canard. Any suggestions here?

[eddiew]

By and large, don't bother to intake spam with FAR. A single shock, plus a radial engine body or a pair of structural intakes usually does well. Going much beyond this ramps up the drag and you end up sacrificing speed in exchange for altitude. Obviously it varies by plane though

If you have the luxury of a front mounting point, 1.5 shocks per engine works well on lighter vessels - but as you can see from the Kerbodyne SSTO thread, it's not mandatory to have that middle one at all Here's a few drone designs that I've found work pretty well with 1-1.5 intakes per rapier.

Javascript is disabled. View full album

[Jovus]

Without seeing your plane I can't give detailed advice on how much rudder it really needs, but my gut reaction, especially since you've said you're using the Mk2 long adaptor, is "at least the small delta with elevon 1 on the end." As you can see above, rudders tend to be bigger than you think they should. This is probably because higher up there's less air flowing over the plane, and so less lateral pressure on the rudder to keep the plane pointed into the airflow. A general rule of thumb is to make the rudder way bigger than you think it needs to be, and then try downsizing until you're comfortable with the drag-stability tradeoff in your intended flight envelope.

There are other solutions to yaw and spiral mode instability, but they're difficult at best to implement with stock parts, and some of the more interesting possibilities may not even be modeled properly by FAR.

One other thing you'll find from Wanderfound's excellent thread if you're looking, but that you might miss if you aren't: FAR now has a wing strength/mass tweakable that you probably saw. The default 1 is really only necessary for the most extreme aerobatics; you can probably reduce this down to 0.5 with your lifting surfaces and 0.3 with your others without ill effect. (I've held a 9g turn for half a minute with my wings set up like this.)

[capi3101]

Okay - night #2. Figured out the controls for procedural wings. Now I just have to figure out how to use them best. Here's my initial craft from last night; basically it was the same craft I was using from Night #1, but with a procedural wing replacing the combination of wings I was using the night before:

It's not clear from the pics, but the wings are set low and dihedral. Before the night was out, I widened the wing at the root, swapped out the Ram Intake quad with a pair of Shock Cone intakes, and replaced the Small Gear Bays with Large Gear Bays (a rescaled Small Gear Bay using this procedure - which in the soup helped me save headaches where the nose was way higher up than the tail of the plane). You might all be able to guess the flight characteristics of that initial design - tail strike after tail strike after tail strike, and when I got the idea to just let it fly off the runway there was an overabundance of pitch control; put the nose at 10 degrees and the plane stalls out and crashes. The aggravation I was having with tail strikes was what prompted me to use the larger gear...

Last night was frustrating; I can't even report the level of relative success I had on the first night, even after making changes to the design.

But let's talk about that initial design for a moment - looking at it this morning, the wings look anemic. I know that the simple 1:1 mass to sum of lift coefficients ratio isn't applicable in FAR, so what am I looking for to know if I've got sufficient lift or not? I'm also wondering if i need to do anything about those flat ends on the backsides of the Engine Nacelles. And should I be doing something different with the tail section? Bear in mind that I did ultimately change the intake setup; I figure if I need to compensate for the loss of the other two Ram Intakes I can use Radials. Speaking of which, are the Radial/Structural Intakes any better in FAR than they are in stock?

[eddiew]

Actually I suspect that's an adequate amount of wing for the weight of the plane... check out the Kerbodyne Karnifex by Wanderfound for a similar airframe with minimal wings Though I'd love to know how you got such pointy tips on them! Mine won't let me go below 0.25m!

However, I'm concerned by your number of intakes. The obvious thing is; planes in the real world don't look like that, and there's a good reason. You've got two huge blunt surfaces either side of the fuselage, and it'll be making horrible drag. Honestly, I think you could dump the nacelles altogether and put a single (or double via a bi-adapter) shock cone on the front end, with a couple of structural intakes at the wing roots (again, see the Karnifex). With careful flight, this would still get you to 30km or better, assuming the rest of the airframe is stable. In stock, people favour ram intakes because their weight-per-intake-area is better, but in FAR it's all about minimising drag, and shock cones are superior for that job.

I'd recommend getting the exposed monoprop tanks into the cargo bay, and using just the little spheres, since they're also a draggy thing to have outside. For the same reason, I'd be quite tempted to swap the turbojet for a rapier (if available) since this will get rid of the little orange engines and reduce drag.

The tail fins can be way back, right on the engine itself. The further back they are, the more stable your flight will be. You can optionally lift the horizontal tail fins up a bit, pulling your CoL to the upper side of the plane, which will help it want to stay upright.

Also, have you checked what happens when the tanks are empty? It looks suspiciously like the CoM might creep back behind your CoL...

Lastly, I suspect that you may do better by splitting the full size MK2 tank into two half tanks, and putting the cargo bay in the middle of them. It's hard to stress enough how much easier it is for you to carry varied payloads when the cargo bay sits at the CoM

*edit* P.S. procedural control surfaces will look much prettier on those wings!

[Yemo]

For wings, you should consider B9 Procedural Parts.

And for Landing and some engine balancing, you might want to take a look at the FAR/NEAR usability Package.

[WhiteKnuckle]

But let's talk about that initial design for a moment - looking at it this morning, the wings look anemic. I know that the simple 1:1 mass to sum of lift coefficients ratio isn't applicable in FAR, so what am I looking for to know if I've got sufficient lift or not? I'm also wondering if i need to do anything about those flat ends on the backsides of the Engine Nacelles. And should I be doing something different with the tail section? Bear in mind that I did ultimately change the intake setup; I figure if I need to compensate for the loss of the other two Ram Intakes I can use Radials. Speaking of which, are the Radial/Structural Intakes any better in FAR than they are in stock?

Ok, here's what I'd do:

1. Ditch the bi-couplers. You've got 6 intakes for one engine... 2 would be enough, 4 (2 shock cones and 2 engine bodies) is fine.

2. Ditch the monoprop. Unless I'm missing something there is no RCS and no docking port, so why are you carrying Mono? If you do need it I would put one inline tank at the front just behind the nose cone.

3. Never leave exposed nodes like you have at the back of the nacelles. Put nosecones on them to reduce drag.

4. Move all your little rockomax engines and all your rear canards back as far as possible. You should have more than enough pitch control, so moving the CoL back is not going to hurt anything.

5. Put two more sets of control surfaces on the main wings. Have the outermost set be set to Roll control. Have the inner two sets control nothing but activate them as spoilers. Set one set's Spoiler deflection to 45* and the other set to -45* (this means when you hit the brakes one set goes up and one set goes down, balancing each other out so you don't get any weird control movements)

6. Put a reaction wheel up front just behind the nosecone. This will help you at high altitudes when your control surfaces don't have much impact.

7. I would make the nacelles longer and carry most of my fuel there. I would not carry any fuel at all in the rear Mk2 adaptor, and I would lock off the fuel in the front Mk2 adaptor to keep the CoM forward.

[Renegrade]

But let's talk about that initial design for a moment - looking at it this morning, the wings look anemic. I know that the simple 1:1 mass to sum of lift coefficients ratio isn't applicable in FAR, so what am I looking for to know if I've got sufficient lift or not?

<Aussie>That's not a wingless airplane, THIS is a wingless airplane!</Aussie>

[capi3101]

Before the night was out, I widened the wing at the root, swapped out the Ram Intake quad with a pair of Shock Cone intakes, and replaced the Small Gear Bays with Large Gear Bays

Two of y'all mentioned the need to swap out the quad Rams - so I felt it necessary to reiterate this part of my post from this morning. Not trying to be a jerk; just re-iterating...

Actually I suspect that's an adequate amount of wing for the weight of the plane... check out the Kerbodyne Karnifex by Wanderfound for a similar airframe with minimal wings Though I'd love to know how you got such pointy tips on them! Mine won't let me go below 0.25m!

I'm using Procedural Wings; the controls will let you get the tips down to that size.

Seriously, that's enough wing? Wow...I wouldn't have thought so. How can I tell if I've got enough wing for a given design? Is it one of those green/red number parameter things? Seriously, I still don't know more than "red is bad" with those.

*edit* P.S. procedural control surfaces will look much prettier on those wings!

No doubt, but I'm still trying to figure out the Procedural Wings mod at the intended functions of all the parts. Last night the first set of wings I had on my plane were the "movable wing" part - and things did not go well at all.

Also, have you checked what happens when the tanks are empty? It looks suspiciously like the CoM might creep back behind your CoL...

The RCS Build Aid data is up there - the position of the CoM is almost completely stable; it actually shifts forward slightly as the craft burns through its fuel.

I'd recommend getting the exposed monoprop tanks into the cargo bay, and using just the little spheres, since they're also a draggy thing to have outside. For the same reason, I'd be quite tempted to swap the turbojet for a rapier (if available) since this will get rid of the little orange engines and reduce drag.

Well...those exposed tanks are the main reason why the CoM is balanced; they kinda need to be there...

2. Ditch the monoprop. Unless I'm missing something there is no RCS and no docking port, so why are you carrying Mono?

I'm using it as ballast. If you look at the SPH shot of the plane, you'll note the RCS Build Aid data, which shows the DCoM offset at 0.01m - the CoM hardly moves at all during flight. I pulled that off by adding those mono cylinders. Now, if they're adding drag and ultimately they're the root cause of why I'm not making space, I'll happily ditch the things...

Lastly, I suspect that you may do better by splitting the full size MK2 tank into two half tanks, and putting the cargo bay in the middle of them. It's hard to stress enough how much easier it is for you to carry varied payloads when the cargo bay sits at the CoM

Might be worth doing, especially since the cargo bay is being used for equipment already (I want to get the basics of flight in FAR down before I try to start doing anything useful). I worry that doing that moving the equipment bay to the center will make it to where the CoM will shift a lot though. Guess I'll have to experiment a bit...

3. Never leave exposed nodes like you have at the back of the nacelles. Put nosecones on them to reduce drag.

I had seen a few designs with nosecones on the back ends and was wondering about this - so thanks. Need for adjustment noted.

5. Put two more sets of control surfaces on the main wings. Have the outermost set be set to Roll control. Have the inner two sets control nothing but activate them as spoilers. Set one set's Spoiler deflection to 45* and the other set to -45* (this means when you hit the brakes one set goes up and one set goes down, balancing each other out so you don't get any weird control movements)

That's for when it comes time to land, right? Like when I've been travelling via plane, and the plane lands and the whole damn wing looks wigged out - that's to help slow the plane down, right? Noted.

Could I set one set up as flaps (maybe the inner set)? Would there be any logic to doing that?

6. Put a reaction wheel up front just behind the nosecone. This will help you at high altitudes when your control surfaces don't have much impact.

Actually, there is a Stabilizer and two Reaction Wheels inside the equipment bay already. Now, admittedly I'm using the old DocMoriarty soup rule of 1.5 kN of SAS per tonne of mass, so I don't know whether or not that's overdoing it in FAR.

7. I would make the nacelles longer and carry most of my fuel there. I would not carry any fuel at all in the rear Mk2 adaptor, and I would lock off the fuel in the front Mk2 adaptor to keep the CoM forward.

The front adapter is mostly empty as it is - it's just carrying around a little bit of Oxidizer and not much else (again I'm using soup rules there - 600 total units of LF and 400 units of oxidizer for a single-Turbojet craft). The bulk of the fuel is in the center tank; were I in the soup I'd try to put all the fuel into a single rocket fuel tank but I don't know how much of that kind of shenanigans I can get away with in FAR. I'm also not sure how to make Nacelles any larger than they are, unless I'm just misunderstanding what you're telling me I should do here.

For wings, you should consider B9 Procedural Parts.

And for Landing and some engine balancing, you might want to take a look at the FAR/NEAR usability Package.

I'm using Procedural Wings already. I haven't even tried to land yet - I'm more concerned with "achieving stable flight at all levels" at the moment - but I might check out the usability package once I turn my thoughts that direction.

Here's a question for y'all - about how strong should I be setting the control surfaces? I imagine that some of the issues I'm still having stem from having control surfaces set to 100% for their given intent (i.e. elevators/canards at 100% pitch, ailerons at 100% roll, rudder at 100% yaw). One lesson learned last night is that "0" was somewhere in the middle; if you turned it all the way down for a given axis, it would just react in the opposite direction - and once I figured this out, I actually had a halfway successful flight (right up until the plane stalled for no apparent reason at 8k and went into an un-recoverable spin...

[Hodo]

For wings, you should consider B9 Procedural Parts.

And for Landing and some engine balancing, you might want to take a look at the FAR/NEAR usability Package.

If only b9procedural wings worked for me. And he isnt responding in his thread, so no clue, I gave up on them.

[WhiteKnuckle]

Seriously, that's enough wing? Wow...I wouldn't have thought so. How can I tell if I've got enough wing for a given design? Is it one of those green/red number parameter things? Seriously, I still don't know more than "red is bad" with those.

There's no hard and fast rule about how much wing is enough. Can you take off (and land) at a reasonable speed? You've got enough wing. Can't take off before the end of the runway? Probably need more wing. taking off halfway down the runway at 100m/s? You've got more than enough wing, it makes landing and takeoff easy but will be slowing you down at mach 5.

The RCS Build Aid data is up there - the position of the CoM is almost completely stable; it actually shifts forward slightly as the craft burns through its fuel.

Well...those exposed tanks are the main reason why the CoM is balanced; they kinda need to be there...

I'm using it as ballast. If you look at the SPH shot of the plane, you'll note the RCS Build Aid data, which shows the DCoM offset at 0.01m - the CoM hardly moves at all during flight. I pulled that off by adding those mono cylinders. Now, if they're adding drag and ultimately they're the root cause of why I'm not making space, I'll happily ditch the things...

Yeah I'd ditch the mono, it's not helping you both in terms of weight and drag.

I'm not someone who is religious about keeping wet/dry CoM in almost the same place. I don't mind the CoM moving around as long as it isn't making the plane unstable at any point. Generaly I try to make an aircraft that gets more stable when it's empty, that way when I'm coming in for re-entry at 2km/s I don't have to worry about a twitchy responsive aircraft trying to flip out and kill me.

So if you need to put something in to balance the weight, make it something inline. But cut out as much stuff as possibe as long as you keep the CoL and CoM in the right order.

That's for when it comes time to land, right? Like when I've been travelling via plane, and the plane lands and the whole damn wing looks wigged out - that's to help slow the plane down, right? Noted.

Could I set one set up as flaps (maybe the inner set)? Would there be any logic to doing that?

Yeah, spoilers are air brakes. When you set a control to act as a spoiler they will be put into the Brake action group so they come on when you press the B key or key the brakes on the upper menue.

Having some airbrakes will help you a lot if you come in too hot and are going to overshoot the runway. They also help a lot once you touch down and need to stop.

Flaps make the wing they're mounted on produce more lift (also drag) so you can lift off at a lower speed. Just remember to turn them off after you take off or they will slow you down. They will need to be set to an action group.

Actually, there is a Stabilizer and two Reaction Wheels inside the equipment bay already. Now, admittedly I'm using the old DocMoriarty soup rule of 1.5 kN of SAS per tonne of mass, so I don't know whether or not that's overdoing it in FAR.

One or two reaction wheels is enough. I would just take it out of the cargo bay and put it in front. This gives the wheel a longer arm to the CoM and makes it more efficent and frees up space in your cargo bay.

The front adapter is mostly empty as it is - it's just carrying around a little bit of Oxidizer and not much else (again I'm using soup rules there - 600 total units of LF and 400 units of oxidizer for a single-Turbojet craft). The bulk of the fuel is in the center tank; were I in the soup I'd try to put all the fuel into a single rocket fuel tank but I don't know how much of that kind of shenanigans I can get away with in FAR. I'm also not sure how to make Nacelles any larger than they are, unless I'm just misunderstanding what you're telling me I should do here.

Disregard my comments about fuel. As long as it's balanced it's good.

Here's a question for y'all - about how strong should I be setting the control surfaces? I imagine that some of the issues I'm still having stem from having control surfaces set to 100% for their given intent (i.e. elevators/canards at 100% pitch, ailerons at 100% roll, rudder at 100% yaw). One lesson learned last night is that "0" was somewhere in the middle; if you turned it all the way down for a given axis, it would just react in the opposite direction - and once I figured this out, I actually had a halfway successful flight (right up until the plane stalled for no apparent reason at 8k and went into an un-recoverable spin...

Most control surfaces you want at 100% for what they are, and 0% for the things they are not. The one exception is the front canards which will usualy stall first. So you can set them lower say 75% or 50% which will make them less effective but also less likely to stall.

One great way to see this in action is FAR's aerovis function. Turn on "Tint Stall" and fly around, you'll get a much better idea of what is causing you problems when you can see exactly what part is stalling.

Edited February 26, 2015 by WhiteKnuckle

[Crzyrndm]

RE: How much wing is enough

In the static analysis tab, you can determine what your level flight AoA will be for a given speed, altitude, and flap setting (for takeoff). It's on the right above the stability derivatives (as is Cl / Cd, velocity in m/s, and a few other useful numbers). If that number is too high you're going to be stalling or descending (can't maintain level flight). If it's too low (one of my planes cruises at 25km with <1 degree AoA...) you probably have too much wing. I normally try and keep it around 5 degrees.

NOTE: AoA refers to wing AoA. If you tilt the wing up a few degrees, your nose can be right on prograde while maintaining level flight and FAR will report it as such

Here's a question for y'all - about how strong should I be setting the control surfaces? I imagine that some of the issues I'm still having stem from having control surfaces set to 100% for their given intent (i.e. elevators/canards at 100% pitch, ailerons at 100% roll, rudder at 100% yaw).

For the most part, use deflection to set how much reaction you have, and set the response to 0 or +/- 100% depending on what you want it to do.

Other %'s are more for when you have a multi-tasking control and you want to set it's priorities a bit different. For example: elevons control pitch and roll, but you often want all of their reaction for pitch, but only a small amount for roll. You set the control deflection based on 100% pitch and then reduce the roll % so that it doesn't use full deflection when it doesn't need to.

Thats how I do it anyway. Much simpler than trying to work out % deflection for everything.

Edited February 26, 2015 by Crzyrndm

[capi3101]

Another quick question for y'all - it's been mentioned before that Turbojets and RAPIER engines were nerfed for FAR so that they don't produce so much power they tear your planes apart. By how much have those engines been nerfed, does anybody know? Was the Basic Jet also affected?

[NathanKell]

Just to reinforce Crzyrndm's point: the only way to really know how much wing you need is that panel. You can input whatever speeds and altitudes you like; I would suggest first checking takeoff. Increase Mach (and hit calculate) until your AoA is reasonable. If the m/s turns out to be more than 120 or so, you need to add flaps or more wing; 270mph is rather fast to be taking off. Then test up at your cruising altitude and speed, maybe 10km and mach 2? See what the AoA is like there. If it's more than 5 degrees, worry.

[Crzyrndm]

Source: https://github.com/ferram4/Ferram-Aerospace-Research/blob/master/GameData/FerramAerospaceResearch/FerramAerospaceResearch.cfg#L694

Generic 50% thrust for all engines that use intake air as a propellant

Turbojet: Reduced thrust to 110kN, reduced max effective velocity to 1800m/s (compared to 2400 stock...)

Rapier: Reduced thrust to 100kN in airbreathing mode, reduced max effective velocity to 1700m/s

Basic Jet: Still (?) 150kN, reduced max velocity to approx mach 1

Edited February 26, 2015 by Crzyrndm

[WhiteKnuckle]

Ok I just made a quick copy of your ship capi to see if it had any fatal flaws and to show you a few design details I'd include.

I don't have P-wings so that's the biggest difference. Anything heavy that I could stick up front I did, with the reaction wheel as far forward as possible to give it a lot of leverage.

At the back a set of tailstrike landing gear, and I moved the rockomax engines to a 45* offset so I could move the tail surfaces back farther.

Tailstrike gear in action.

Made it into an 85k orbit, had to unlock the front tank to circularize which to me is fine, you can use all the fuel in the front tank you just have to wait till the rear tanks are empty.

Landing under 100m/s and no hint of stalling... this thing has more than enough wing.

Made it with fuel to spare. Also note the spoilers activated on the inner wing.

Here's the craft file if you want to rip it apart to see what I did. But it wasn't much, the basic design is sound, and honestly flew like a dream once I made a few little tweaks.

https://www.dropbox.com/s/m27wbxlfo3k0cr6/Capi%20Test%20drone%20Mk1.craft?dl=0

Action groups:

1. Toggle jet engine

2. Toggle rocket engines