Official FAR Craft Repository

[blowfish]

It looks like you might have some pitch instability beyond 10 degrees - moving the wings all the way back would help somewhat (and it could get worse beyond 15 degrees but your graph doesn't go that high so I can't tell). Also, isn't Kerbin re-entry more like Mach 6-7?

[Wanderfound]

The Shuttle came in at extreme pitch, but it didn't hold that posture aerodynamically; it used the OMS as a stability aid. To replicate that in KSP, slap some Vernors on and activate RCS.

[eddiew]

The Shuttle came in at extreme pitch, but it didn't hold that posture aerodynamically; it used the OMS as a stability aid. To replicate that in KSP, slap some Vernors on and activate RCS.

I never knew that... I wouldn't have expected thrusters to make much odds when hitting the stratosphere at mach 20 ^^;

[Nansuchao]

I never knew that... I wouldn't have expected thrusters to make much odds when hitting the stratosphere at mach 20 ^^;

Here you can see a typical Space Shuttle mission made in a more or less realistic procedures of launch and re entry.

[tetryds]

Titov, you are possibly going overkill on dihedral effect, that is a very commom mistake.

Reduce the sweep of the main wings, even if that does not solve yor problems it will help a lot.

Maybe just removing that wing piece from the leading edges.

[FourGreenFields]

Titov, you are possibly going overkill on dihedral effect, that is a very commom mistake.

Reduce the sweep of the main wings, even if that does not solve yor problems it will help a lot.

Maybe just removing that wing piece from the leading edges.

Wasnt dihedral effect yaw and roll stability though? From what I get ("When the pitch is a bit over the prograde vector, it goes frontside rear, upside down, etc.") it's pitch instability... ?

[Kitspace]

If the blue overlay graph shows the aerodynamic pressure why not place the center of pressure marker at the point of the highest peak of the blue graph?

[kcs123]

If the blue overlay graph shows the aerodynamic pressure why not place the center of pressure marker at the point of the highest peak of the blue graph?

What if you have two or more peaks of same apmlitude ? Where you will place center of pressure marker ?

You need to spend some time in crafting and watch how blue line changes on your various designs to be more helpfull than confusing.

But when you overcome first mistakes, it will be quite good tool in design process.

[tetryds]

Wasnt dihedral effect yaw and roll stability though? From what I get ("When the pitch is a bit over the prograde vector, it goes frontside rear, upside down, etc.") it's pitch instability... ?

Yes but he is certainly not becoming pitch unstable, he is just flipping over/around, if he is getting pitch unstable his mass distribution is very off.

There are many things to do when reentry is unstable, this is just one of them.

Also, real life shuttles had very complex control systems, and that changes everything.

So yeah, some changes are needed to the design to make it functional in the game.

If the blue overlay graph shows the aerodynamic pressure why not place the center of pressure marker at the point of the highest peak of the blue graph?

Because that is not really how it works, haha.

[Halsfury]

First nuFAR supersonic aircraft running on 1 basic jet engine mach 1.3 top speed, with a maximum tolerable speed of mach 4.5 (with the turbo ramjet)

Wave drag cross sectional area is only 1.06m^2, it's actual cross section is 2.33m^2. Are there any ways you guys think it could be made better?

Actually, I managed to make it better by adding 2 finlets on the belly at the rear, now wave drag area is 1.01m^2

Edited June 12, 2015 by Halsfury

[tetryds]

First nuFAR supersonic aircraft running on 1 basic jet engine mach 1.3 top speed, with a maximum tolerable speed of mach 4.5 (with the turbo ramjet)

Wave drag cross sectional area is only 1.06m^2, it's actual cross section is 2.33m^2. Are there any ways you guys think it could be made better?

http://i.imgur.com/NR4iSFC.png

http://i.imgur.com/PRnlJgT.png

Actually, I managed to make it better by adding 2 finlets on the belly at the rear, now wave drag area is 1.01m^2

Yes, avoid straight leading/trailing edges at all costs, move your elevators forward so their tip ends where the engine ends and keep the number of ballasts to a minimum.

You won't gain a lot of speed from doing that but will be able to stay fast using less fuel.

[Halsfury]

Yes, avoid straight leading/trailing edges at all costs, move your elevators forward so their tip ends where the engine ends and keep the number of ballasts to a minimum.

You won't gain a lot of speed from doing that but will be able to stay fast using less fuel.

Thanks a ton, that little plane now has no issue going to mach 2 at 10,000m, I tried out several different methods, but the tip about moving the elevators so they didn't hang out behind the aircraft was rely the most helpful

Here are the new and improved stats :

Max cross section: 2.35995m^2 with a wave drag area of just 0.62m^2 critical mach number is 0.77 which is tolerable.

See any other design faults? I kept with the drag bodies for their area ruling properties

Edited June 13, 2015 by Halsfury

[Wanderfound]

Thanks a ton, that little plane now has no issue going to mach 2 at 10,000m, I tried out several different methods, but the tip about moving the elevators so they didn't hang out behind the aircraft was rely the most helpful

Here are the new and improved stats :

Max cross section: 2.35995m^2 with a wave drag area of just 0.62m^2 critical mach number is 0.77 which is tolerable.

http://i.imgur.com/oA8xmKH.png

See any other design faults? I kept with the drag bodies for their area ruling properties

Not so much faults as tweaks.

1) Why the torque wheels? You don't need them; the capsule torque is more than enough.

2) How do you have your control surfaces set up? Does it stall or flip out of control at full stick? What sort of sustained G-load can it manage in a turn?

3) Did you remember to drain the monoprop from the cockpit and the oxidiser from the Oskar B's?

4) What wing mass tweakable settings are you using?

5) Did you remember to raise the brake torque on the rear landing gear?

6) What sort of speeds is it taking off and landing at?

7) How does it go on the track? http://forum.kerbalspaceprogram.com/threads/123650-Kerbinside-Air-Race

[FourGreenFields]

Thanks a ton, that little plane now has no issue going to mach 2 at 10,000m, I tried out several different methods, but the tip about moving the elevators so they didn't hang out behind the aircraft was rely the most helpful

Here are the new and improved stats :

Max cross section: 2.35995m^2 with a wave drag area of just 0.62m^2 critical mach number is 0.77 which is tolerable.

http://i.imgur.com/oA8xmKH.png

See any other design faults? I kept with the drag bodies for their area ruling properties

Any chance removing the antenna makes it more aerodynamic? Worth a try imo.

Also, always calculate wave drag, etc. with raised gear. And build with mostly raised gear too - else you wont see exactly what you need to change.

[Halsfury]

1) Why the torque wheels? You don't need them; the capsule torque is more than enough.

A: They are really just cause I wanted drag bodies smaller than the oscar tanks, they don't change a thing

2) How do you have your control surfaces set up? Does it stall or flip out of control at full stick? What sort of sustained G-load can it manage in a turn?

A: Goes around 6g's at supersonic speeds above 3000m, around 9 g subsonic. below 3000m yanking the stick is not advisable

3) Did you remember to drain the monoprop from the cockpit and the oxidiser from the Oskar B's?

A: got rid of oxidizer, forgot about the cockpit mono prop

4) What wing mass tweakable settings are you using?

A: Never changed them so all are at 1

5) Did you remember to raise the brake torque on the rear landing gear?

A: After I overshot the runway on landing I corrected it

6) What sort of speeds is it taking off and landing at?

90m/s takeoff, and rather quick landings at 120m/s #pilotlazyness

7) How does it go on the track? http://forum.kerbalspaceprogram.com/threads/123650-Kerbinside-Air-Race

A: Hmmm.... I will find out.

EDIT:

FourGreenFields, I chose the antenna because I've seen spikes used to push wave drag off the main body in real life

Also is that an Irish Air Force Roundel?

EDIT: I tried removing the spike made from that antenna and the wave drag jumped from 0.69m^2 to 0.9m^2, so my hypothesis was correct :-)

Edited June 13, 2015 by Halsfury

[gilflo]

To WANDERFOUND

Thank you for our discussion and your advices a few posts ago. I built a long range SSTO cargo able to deliver a 6T cargo load to Minmus or Mun and return without refueling using RAPIER and Nukes

http://www.hostingpics.net/album/gilflo-242771.html

Edited June 13, 2015 by gilflo

[Wanderfound]

To WANDERFOUND

Thank you for our discussion and your advices a few posts ago. I built a long range SSTO cargo able to deliver a 6T cargo load to Minmus or Mun and return without refueling using RAPIER and Nukes

http://www.hostingpics.net/album/gilflo-242771.html

http://img11.hostingpics.net/pics/537135screenshot14.png

Give it an LKO top-up and it should be able to land and return, too.

[gilflo]

What you mean LKO top up?

- - - Updated - - -

About air intakes, I experienced some engines stall at high AOA (>15) below 24km that's why i put 2 air intakes per engines, the second one being slightly turn down( around 5°negative AOA on ground) so that they'll be more in airflow at high AOA, but i don't know whether it is simulated in FAR

[Wanderfound]

What you mean LKO top up?

Refuel it from the fuel depot that you have parked in an 80x80 Kerbin orbit. If you don't already have such a thing, I highly recommend building one; it massively enhances the capabilities of your spaceplane fleet.

About air intakes, I experienced some engines stall at high AOA (>15) below 24km that's why i put 2 air intakes per engines, the second one being slightly turn down( around 5°negative AOA on ground) so that they'll be more in airflow at high AOA, but i don't know whether it is simulated in FAR

One and a bit shock cones per jet is plenty; if you have that many intakes and you're having air starvation problems below 30,000m, the issue is intake build order. All of the air is going to a couple of the jets before the others get a look-in. I highly recommend installing the Intake Build Aid mod; it takes all the hassle out of intake placement.

As well as all that, there's the point that you shouldn't be using the heavy stack-mount intakes in positions where you can't take advantage of their inline air-shielding advantage. If you're mounting 'em radially, use radial intakes. Looks better, lighter, doesn't create as much drag.

Another long-range demonstrator, this time with four jets:

Javascript is disabled. View full album

Craft file at https://www.dropbox.com/s/lksqznhhh7dw0u5/Kerbodyne%20Flinders.craft?dl=0

Edited June 13, 2015 by Wanderfound

[gilflo]

Well i have got intake build aid and I used it to build the Avenger.

I also got a big fuel depot in orbit, but this SSTO dont need it as it is able to fly to Mun or Minmus, deliver a satellite and fly back to Kerbin and land without need of any refueling.

For landing I just need to experiment a 24-77 Twitch engine on top of cockpit to flip it down just before landing

[FourGreenFields]

FourGreenFields, I chose the antenna because I've seen spikes used to push wave drag off the main body in real life

Also is that an Irish Air Force Roundel?

EDIT: I tried removing the spike made from that antenna and the wave drag jumped from 0.69m^2 to 0.9m^2, so my hypothesis was correct :-)

Yes, it's the Irish Air Corps roundel.

Messing around never hurts though. Once tried it too, and it increased drag on the design I used.

[Halsfury]

Yes, it's the Irish Air Corps roundel.

Messing around never hurts though. Once tried it too, and it increased drag on the design I used.

In fact I tried the same thing with a new 2 engine build, I took the whole thing to top speed at 1000m and got to around mach 1.2, then I retracted the spike and sure enough my excess power reading increased and I began accelerating even more

[Wanderfound]

With the nosespikes...sometimes they help, sometimes they don't. It varies ship by ship; you need to check it in the SPH.

Another RAPIER/Nuke/RAPIER Muntripper:

Javascript is disabled. View full album

Craft file at https://www.dropbox.com/s/11a7pkpmceu7oap/Kerbodyne%20Norfolk.craft?dl=0

[gilflo]

I noticed a kind of issue with temperature gauge.

I am in orbit on the first pic Time 4D:02:14 and T° is 416

On the 2nd pic Time is 3sec later 4D:02:17 Temp is 414°

On the 3rd pic Time is more than 1h later, 4D:03:22 I switch on another ship, made an orbit and switch back to my SSTO: Temp is still 414°

Temp is not going down when you're not here! Is it a FAR issue or a stock issue ?

[tetryds]

I noticed a kind of issue with temperature gauge.

I am in orbit on the first pic Time 4D:02:14 and T° is 416

On the 2nd pic Time is 3sec later 4D:02:17 Temp is 414°

On the 3rd pic Time is more than 1h later, 4D:03:22 I switch on another ship, made an orbit and switch back to my SSTO: Temp is still 414°

Temp is not going down when you're not here! Is it a FAR issue or a stock issue ?

http://img11.hostingpics.net/pics/425790screenshot51.png

http://img11.hostingpics.net/pics/536484screenshot52.png

http://img11.hostingpics.net/pics/304763screenshot53.png

FAR does not even touch how thermal stuff works on KSP, it's not a FAR issue.