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

[futrtrubl]

So all these rockets in real life really are statically unstable?

After some more experimentation, I was able to get to orbit with some rockets with higher CoM than CoL. The most important factor I discovered was that the prograde flight assistant is helpful only if the pod's reaction wheels are disabled. If they are still enabled, then SAS will jitter so much as to flip the rocket around.

I think that much of the problem comes down to limitations of KSP itself. Beyond fixing the jittery flight assistants, I would really like to have some small fins just to lower the CoM a little for small rockets. A really big problem is that SRBs in KSP are crappy compared to real life: they don't have any gimbal capability, and the pod's reaction wheels are not enough to reliably keep it from flipping. Also, there is no way to adjust the bore so that the TWR doesn't get ridiculously high at the end of the burn.

I assume you mean lower the CoL ;'] Check out RoverDude's Sounding Rockets mod, it has three extremely tiny to small fins made for exactly this.

Yes, adjusting the grain in SRBs is on my mod wishlist.

[gilflo]

Odds are the CoL is moving further back or your CoM is moving forward as fuel drains out of the craft. What I do is I use TAC fuel Balancer and I leave one tank empty on the craft for weight transfer in flight. Real aircraft do this exact thing for the same reasons. I will lock that tank most of the flight but once the nose gets heavy I will shift fuel towards the rear of the craft to bring the CoM near the CoL as it shifts back.

Not easy to do if you don't know exactly where you COL is moving. I know how my COM is moving and I try to minimize movement by means of Goodspeed and TAC fuel balancer also

[Jumpyyoza]

How do I set air brakes? I'm really confused by all the new options made available with FAR.

[Wanderfound]

How do I set air brakes? I'm really confused by all the new options made available with FAR.

Choose two pairs of control surfaces, preferably near to CoM. Use the right-click menu to set both pair as spoilers. Change the max flap/spoiler deflection on one to 85; on the other set it to -85. Set up an action group to toggle the spoilers on and off. By default, they'll be linked to the brakes.

Edited April 9, 2015 by Wanderfound

[gilflo]

What maxi speed do you reach on turbojet before switching on rockets ? It seems that Mach 4.2 and 1450m/s is maximum

[ThorBeorn]

...

Yes, adjusting the grain in SRBs is on my mod wishlist.

OT but there are at least two mods for this in RealFuels and EngineThrustController (could be outdated) by HoneyFox. Then there's that mod advanced SRB's that's in dev.

[Van Disaster]

What maxi speed do you reach on turbojet before switching on rockets ? It seems that Mach 4.2 and 1450m/s is maximum

I just speed profiled FAR-tubojets and Rapiers in atmo mode - over the page I did an attempt at altitude profiling also, but honestly I don't think there is one with any practical effects.

Real rockets generally have better gimballing engines than ours, too.

[Guest]

New FAR Ready highG plane, any feedback?

http://www./download/tcql14t5k8b7973/¬_F-52_Deino.craft

thread

[rpayne88]

Help me make this stable:

Its good until I start burning my rockets, then it completely flips out.

[Svm420]

@rpayne88

You need to be going faster to be up at 20km at least mach 2.5 better yet mach 3. How do the numbers look at those speeds?

[Hodo]

Your wings and tails are crooked. I would use the rotate function and rotate the wings just a bit so that your tail and engines are straight along the sides of the craft instead of being canted inwards on the craft.

[futrtrubl]

It looks like your rockets are not inline with your center of mass. Turn on all the centers for more informative screenshots.

[Van Disaster]

Pitch controls perhaps further from where I suspect CoM is also.

[Honeybadga]

I'm having an issue with the MK2 Cargo Bay 2m from B9 Aerospace. I've put a bunch of science equipment, some batteries, a Kerbal Engineer Redux Computer Flight Unit and an RT2 antenna inside the cargo bay. In the SPH, the cargo bay's context menu is telling me that the total number of parts shielded by the cargo bay is 20. However once I launch the plane, on the runway the same context menu is telling a different story: number of parts shielded is 3.

The real trouble begins after takeoff. Once I approach around 300ish m/s velocity, stuff starts exploding and the flight results screen is telling me that the connections between the parts inside the cargo bay and the cargo bay itself are failing due to aerodynamic stress. The plane remains operational, but I can't do experiments like this. I haven't tested any of the other cargo bays.

Here are some screenshots with the issue at hand:

http://imgur.com/a/tUNxg#0

Playing with FAR in KSP 0.90. All mods and their dependencies are up to date. Forum user blowfish told me to ask around here.

[futrtrubl]

Got a problem with the Reflectron DP-10 from RemoteTech. If it isn't shielded it always seems to get destroyed when I hit Mach 1. Tried hiding it inside other parts. Tried adding and increasing breakingForce and breakingTorque but even at 1000 it still happens. Looking at the FAR code I see it makes it's own values YmaxStress and XZmaxStress from templates but I can't figure out what it is using. A bit of a problem as it's the only antenna that is supposed to be able to withstand launch and reentry unshielded.

[Van Disaster]

@Honeybadga: make sure the cargo bay is listed as a cargo bay in this screen:

Fairly sure I had to add "Cargo Fuselage" to get some B9 parts.

Futrtrubl: I've had a lot of problems trying to make a teardrop antenna I made suitably strong, and I still haven't cracked it. Hope you can find out what to set.

[Honeybadga]

@Honeybadga: make sure the cargo bay is listed as a cargo bay in this screen:

*snip*

Fairly sure I had to add "Cargo Fuselage" to get some B9 parts.

Unfortunately that didn't help. I've added an entry called "cargo fuselage" to the 'Cargo Bay title contains:'-section to no avail. Also, the problematic part has 'cargo bay' in its title and that entry already exists.

[futrtrubl]

Futrtrubl: I've had a lot of problems trying to make a teardrop antenna I made suitably strong, and I still haven't cracked it. Hope you can find out what to set.

For now I have set PhysicsSignificance = 1

A bit cheaty but I got places to be yo.

Edit: Nope that failed. The joint still fails.... I am stumped. No idea why it fails when all the other surface mount physics-less parts hold.

Edited April 12, 2015 by futrtrubl

[Wolf_rt]

Ok, i have been having a lot of trouble getting my F-104 replica to behave as expected with FAR, AJE, and B9 installed.

Originally i though it was an issue with the thrust the J79 engine was producing due to the AJE mod. However the more i have looked into it, the more it seems like that is behaving properly.

This is the beginning of the conversation on the AJE thread

http://forum.kerbalspaceprogram.com/threads/70008-0-90-Advanced-Jet-Engine-v2-0-4-Apr-10?p=1833343&viewfull=1#post1833343

In the end, i decided that the thrust i am getting of ~80KN at sea level at Mach 0.5 and 20KN at 10000M should be correct.

However the F-104 should be able to do Mach 1.2 at sea level, and Mach 2 At 10000M. As it stands, it can do Mach 0.95 up to 10000M as the thrust falls away to 20KN due to the AJE mod. It does not seem to be able to go above Mach 1 though.

I have found two figures for the cd of the real F-104. 0.017 (no lift) and 0.048 on wikipedia.

The in game model has a cd of 0.011, rising to 0.25 at Mach 1 then falling to 0.023 at Mach 1.5 (using a larger engine to get to that speed)

This pic shows it maxed out at 10000M, Note that the angle of attack is wrong due to the cockpit being angled, the actual AOA of the wings is 1-2deg i believe.

Note this is a fresh install with only FAR, AJE, B9, Tweak Scale, Procedural Tanks and KJR installed via CKAN.

Tweakscale has been used on all of the stock wings and control surfaces.

The current version of the plane shown above, uses no part clipping, and the weight is ~6000KG dry, as per the actual aircraft. Although i noticed this model is actually around 75% scale.

Edited April 12, 2015 by Wolf_rt

[Kitspace]

Hello!

Does anybody know how are the aerodynamic stress forces calculated?

I mean the forces break a joint off no matter how enforced it is it is not enough.

So either the joint is unrealistically weak or the drag force from a very high angle of attack breaks it unrealistically.

Thank you!

[tetryds]

Hello!

Does anybody know how are the aerodynamic stress forces calculated?

I mean the forces break a joint off no matter how enforced it is it is not enough.

So either the joint is unrealistically weak or the drag force from a very high angle of attack breaks it unrealistically.

Thank you!

Using struts help with flexing, but they do not make your wings stronger.

To make your wings stronger you need to increase their mass, that is a tweakable option available on every wing and control surface when FAR is installed.

The game calculates the stress through the dynamic pressure and wing area directed at the airstream, so if you have high dynamic pressure you can go straight but you can die if you pitch up.

In order to make tighter turns at high speeds and low altitudes, you need to place your wings efficiently so you have as high as possible (resultant lift force)/(total lift force) on your airplane.

[Van Disaster]

Unfortunately that didn't help. I've added an entry called "cargo fuselage" to the 'Cargo Bay title contains:'-section to no avail. Also, the problematic part has 'cargo bay' in its title and that entry already exists.

I'm leaning towards some clipping issue; I sprinkled some parts around randomly & ended up with this...

I have no idea who's fault that is...

[Honeybadga]

I'm leaning towards some clipping issue; I sprinkled some parts around randomly & ended up with this...

*snip*

I have no idea who's fault that is...

Looks like there's no other option for me than to turn off the aerodynamic failures setting for now.

[StahnAileron]

Unfortunately that didn't help. I've added an entry called "cargo fuselage" to the 'Cargo Bay title contains:'-section to no avail. Also, the problematic part has 'cargo bay' in its title and that entry already exists.

I had/have this problem with the stock Mk2 long cargo bay when I while using NEAR (which was last updated back in Dec). Found out it was a transition problem from the SPH to the runway. The fix I wound up with was leaving the Cargo bay OPEN in the editor and manually closing it when launching. Seems the shielded state/flag didn't trigger unless it detected the TRANSITION from open to close, rather than the actual state (or something like that.) Perhaps this workaround will help you. (If you haven't already tried it...)

To simplify this, I go Auto-Actions and set it to toggle my cargo bay action group so it would close automatically on launch load. Funny enough, cargo bays from other mods (in particular my experience with OPT) seem to work fine when left in a closed state from the SPH... I think. I think I got into the habit of just leaving the bays open and auto-closing them to be sure (and to make editing less of a hassle.)

[Honeybadga]

Perhaps this workaround will help you. (If you haven't already tried it...)

I've just tried it but it's not working. However I'm using the B9 MK2 2m Cargo Bay, not the stock one. Indeed, it seems to be a problem with the transition from the SPH to the runway as I've already demonstrated in my other post. Thanks for the input.