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

[Good_Cat]

I have a random question.

Looking at some aircraft high speed aircraft i see the body tapers and gets narrower as the wing span increases and then increases as the section of wing joins the body, i know this is to smooth some effect out ( the aircraft body / wing surface area for a side on cross section increases gradually until the aircraft fuselage is narrowest as the wing wingspan is at its greatest then both decrease towards the tail.

I used to know what this was and why and now i'm bashing my head against a wall trying to remember.

Can anyone tell me what this is.

Here is an example aircraft Dassault Mirage

[Goddess Bhavani]

I have a random question.

Looking at some aircraft high speed aircraft i see the body tapers and gets narrower as the wing span increases and then increases as the section of wing joins the body, i know this is to smooth some effect out ( the aircraft body / wing surface area for a side on cross section increases gradually until the aircraft fuselage is narrowest as the wing wingspan is at its greatest then both decrease towards the tail.

I used to know what this was and why and now i'm bashing my head against a wall trying to remember.

Can anyone tell me what this is.

Here is an example aircraft Dassault Mirage

It's called Area Rule and knowledge of this allows you to decrease supersonic wave drag in nuFAR too. Before the concept of Area Rule, jet fighters had trouble breaking the sound barrier. Once those curvy coke bottle fuselages started appearing, they progressed quickly over a number of years to Mach 2 and beyond

In other news, I just finished my first designed-for-nuFAR aircraft based off a famous Gerry Anderson craft from Captain Scarlet.

This replica has Jeremy Clarkson approved levels of face-tearing acceleration and has a top speed of Mach 3.1. Thanks to nuFAR it is also stable enough to fly without SAS, although leaving it on is recommended for beginners.

Fly with DPCR at 9.0, fudge the number at pilot's discretion. Tweakscale required, as original design had many tiny but functional parts that would be omitted otherwise.

Angel Interceptor craft file on KerbalX:

http://kerbalx.com/crafts/2234

Edited May 10, 2015 by pandoras kitten

[taniwha]

Good_Cat: Area Ruling. Keeping the changes in cross sectional area smooth results in lower wave drag (not sure what that is, but reducing any drag is good).

[ratchet freak]

With area ruling someone should make a set of anti-shock body parts to allow you to fine-tune the yellow line better that just stock parts allow

[UnanimousCoward]

Is there any way to recreate waisting on aircraft in KSP/FAR, or can area rule only be achieved by adding bits to the fuselage?

[mikegarrison]

Good_Cat: Area Ruling. Keeping the changes in cross sectional area smooth results in lower wave drag (not sure what that is, but reducing any drag is good).

Wave drag is, essentially, energy lost in shockwaves. (Or more generally, energy lost due to compressibility, but it's very very small until you closely approach Mach 1.)

Edited May 10, 2015 by mikegarrison

[Gfurst]

Seriously, no one is going to comment on this instead of arguing over stock or FAR? Ferram please tell me it was at least useful....

[ferram4]

@Gfurst: Sorry, didn't get to it, I've been working on some bugfixes.

The data of how it behaves in game is good, but without a comparison to real life planes with cited data, I can't make changes. I don't know if the drag coefficient is too high for what you're looking at, or if the lift coefficient is too low, or what, because you're not posting the data for what you're comparing it to. Especially considering you didn't post the mass of the plane, which is kind of important.

[taniwha]

mikegarrison: Ah, thanks. That makes a lot of sense.

[Good_Cat]

Been waiting on this for a while so download tonight, install tomorrow so i can spend my night shift in work doing something constructive.... like finishing my Panavia Tornado replica(ish).

How far do people go with these sort of concepts, i mean I've toyed with things like calculating mach cone angles and ensuring my wingspan is within them and area ruling (now that i know what i was doing is called) , does anyone go further with their designs and what else.

Edited May 10, 2015 by Good_Cat
Spelling, Grammar and everything else

[darqen27]

@darqen27: And all of that is great and wonderful, but without the log, if it is something on my end, I can't fix it. You might be able to read logs, but I can't read your computer screen from here (though it would save so much time fixing bugs if I could). So with that in mind, would you kindly post the entire, complete log and full reproduction steps?

@Phylan: Update to 1.0.2. Apparently some things changed in between that RealChuteLite relies on.

I apoligize for that. I read the logs, saw KIS and FAR fighting in the VAB, was throwing Null reference exceptions trying to do something with KIS and then a unity4 exception 1 nano-sec afterwards

I'm sure I can reproduce it and get the exact errors for you if needed

[Good_Cat]

Just posted a thread in Addon affairs http://forum.kerbalspaceprogram.com/threads/120632-Procedural-Structural-and-Fuel-Tanks

I've no idea how difficult modding is or how complicated procedural parts are but any comments on this, could a procedural structural/fuel tank be useful. Build it exactly like the stock procedural fairings but it would be interstage or a tailsection.

Is this even feasible.

[ratchet freak]

I apoligize for that. I read the logs, saw KIS and FAR fighting in the VAB, was throwing Null reference exceptions trying to do something with KIS and then a unity4 exception 1 nano-sec afterwards

I'm sure I can reproduce it and get the exact errors for you if needed

You seem to keep missing the point about posting the log. If you don't provide the entire log to ferram he can't figure out what is going wrong, find a file host site and upload the log and post the link for him to get a copy of it. If the log is short enough (cleaned log and then launched and did just the minimum to recreate the issue) then a site like pastebin.com will suffice. Also post the exact steps you did to recreate it.

vague descriptions does nothing but waste everyone's time and forces ferram to guess at what's wrong where the logs will tell him where the problem is with much greater accuracy.

[MatterBeam]

Can someone give me quick rundown of how to use FAR graphs to replace the center of lift? How do I know if I've placd the wings too far forwards or backwards?

[sal_vager]

Guys, I recommend you use the official bug reporting guide for all issues even for mods, and try to reproduce the issue at least once before reporting, one-off events are not useful.

Logs and reproduction steps are essential.

[linuxgurugamer]

Before I report a bug, I'd like to know if someone else is seeing this:

I make a fairly simple plane with delta wings. In the hanger, I modified the tail fin to have 0% for roll and pitch control, yet it still responds to the roll.

Has anyone else seen this? Is there something else I need to do?

This worked before I installed the latest FAR via CKAN. FAR version is 0.15_Euler

Thanks in advance

- - - Updated - - -

@ferram, just an FYI, the Homepage listed in CAKN is wrong, it just brings me to the main KSP page.

[ferram4]

@Krakenfour: Do an AoA sweep at the Mach number you're interested in. If the yellow line slopes down, you're stable. If it slopes up, you're unstable. If it's flat, you're neutrally stable (which is, for our purposes, the same as unstable). If it changes slope as AoA changes, that means at some AoAs you're stable, and at others you're unstable.

@linuxgurugamer: That sounds really screwy, like something isn't saving. First thing I'd suspect is user error, tbh, the second thing I'd suspect is CKAN doing something screwy, because it's done a lot of that recently.

Also, any CKAN issues aren't my problem, I'm not even happy with my stuff there given the issues it's been causing.

[jrandom]

the Homepage listed in CAKN is wrong, it just brings me to the main KSP page.

AAAHHH! Don't bring up CKAN, you'll get smited! (ferram doesn't maintainn the CKAN configs, that's done by the CKAN people)

[futrtrubl]

Just posted a thread in Addon affairs http://forum.kerbalspaceprogram.com/threads/120632-Procedural-Structural-and-Fuel-Tanks

I've no idea how difficult modding is or how complicated procedural parts are but any comments on this, could a procedural structural/fuel tank be useful. Build it exactly like the stock procedural fairings but it would be interstage or a tailsection.

Is this even feasible.

Get Procedural Parts, it does exactly this. I also just added a waisted profile exactly for this type of use.

[Surefoot]

Seriously, no one is going to comment on this instead of arguing over stock or FAR? Ferram please tell me it was at least useful....

Somehow my answer was lost...

I was reacting on your comment about stability. Unstable designs *are* valid, delta wings and almost all modern jet fighters are unstable. And IMHO delta are the way to go if you want to make a beautiful SSTO

If you take a look at SR-71 flight controls, it did have a "SAS" button and flying without it was quite dangerous (it wanted to flip black, mostly) only a few pilots claimed they were able to fly it without SAS. Now most modern jets have it in-built.

If you look at subsonic designs, yes most of them are stable, but their purpose is different. If you want to go hypersonic and keep a decent level of control, without compromising too much on weight / heat distribution / payload you'll have to give away some stability.

My current challenge is to overcome dutch roll and natural pitch-down tendency on my designs, i'm working on it

[NoClass]

Seriously, no one is going to comment on this

Interesting stuff! Do you know the mass of your plane during the level flight test? ...maybe a value for wing loading?

[jrandom]

If you take a look at SR-71 flight controls, it did have a "SAS" button and flying without it was quite dangerous (it wanted to flip black, mostly) only a few pilots claimed they were able to fly it without SAS.

The SR-71 in X-Plane does not appear to have a SAS button (or I just haven't figured out where it is) and it's scary dangerous to fly w/out it.

[Frederf]

Has anyone had trouble with parachute deployment on reentry? It deploys initially, but fails to unfold fully before the thing smacks into the ground. I thought it might be my reentry profile but I've tried a few different ones and the same thing keeps happening. I don't think it's a bug but probably some feature of FAR that I haven't adapted my craft design to account for. Any ideas?

FAR includes "RealChute Lite" which has a totally different method of adjusting the parachute parameters. If I recall the defaults are like 0.01atm 2 seconds and 700m 6 seconds. If the nuFAR-nuStock relationship is anything like the oldFAR-oldStock relationship, FAR is slipperier and 700m is too late for certain designs.

Depending on what mods you have installed (e.g. Stock Fixes) the interface with these parameters gets a little cluttered and confusing with some being completely ineffectual and others quite hidden if you're used to the stock. I believe an installation with just FAR and its dependencies shouldn't have any adjustable bars. The "toggle info" option is the one you want for adjustments to deployment parameters and/or the action menu and click the part in VAB.

[jrandom]

I built my first plane using the yellow cross section curvature guide to help minimize wave drag (and a little bit of area rule, but not much since I don't have Proc Parts installed yet), and this thing just screams through the air. (Previous designs where I didn't pay attention to the yellow curve had trouble pushing past Mach 1, even with more engines. Yay phyics!)

As I cross the Mach 2.5 boundary (or so, I wasn't paying close attention -- neighborhood of 700m/s at 12-13km) I lose all yaw control. What specific effect am I hitting, and do I just need taller yaw fins/controls to combat that? I'd like to push this thing up to Mach 3.

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Edited May 10, 2015 by jrandom

[tetryds]

I built my first plane using the yellow cross section curvature guide to help minimize wave drag (and a little bit of area rule, but not much since I don't have Proc Parts installed yet), and this thing just screams through the air. (Previous designs where I didn't pay attention to the yellow curve had trouble pushing past Mach 1, even with more engines. Yay phyics!)

As I cross the Mach 2.5 boundary (or so, I wasn't paying close attention -- neighborhood of 700m/s at 12-13km) I lose all yaw control. What specific effect am I hitting, and do I just need taller yaw fins/controls to combat that? I'd like to push this thing up to Mach 3.

http://imgur.com/a/DJcYZ

As the Mach number increases, the effectiveness of your wings decrease, your vertical tail is already very small, it just gets to a point where it's useless.

Try at least doubling them.