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#12165282 Mar 14, 2016 at 05:17 AM
Brigadier Ge...
343 Posts
What cool military aircraft need to be tinkered with a bit, and who is willing to help. This thread should cover it!
Raider1

(Combat call-signs: Raid-1, Raid-2)
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#12166580 Mar 14, 2016 at 03:24 PM · Edited over 2 years ago
Colonel
560 Posts
A version of FGUK's Eurofighter Typhoon (naval version) is able to shoot missiles so this could be useful for the ops.
Mav
Breakin' the sound barrier everyday!
Peace through superior AIRPOWER

Buzzard Viper Driver, 510th FS.
Reaper Eagle Driver, 493d FS.
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#12167214 Mar 14, 2016 at 06:37 PM
Colonel
456 Posts
FGUK site seems down, where can this aircraft be downloaded from?
"No one dared to make a slip, the stranger there among them had the big iron on his hip."
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#12167389 Mar 14, 2016 at 07:20 PM
Colonel
560 Posts
Yeah it's down. We've got some website issues recently so the admins need to fix it.
The download link was on a Dropbox link, in the forum so we can't get it unless I upload on my DB and let you download it if you need it now.
Mav
Breakin' the sound barrier everyday!
Peace through superior AIRPOWER

Buzzard Viper Driver, 510th FS.
Reaper Eagle Driver, 493d FS.
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#12167421 Mar 14, 2016 at 07:27 PM · Edited over 2 years ago
Colonel
560 Posts
https://www.dropbox.com/sh/gxltcomfxf94bf4/AADq97mJ4Hh1cLMe87KfTv4ra?lst

It's not the latest version, but here is it (found it by searching on Google).
Mav

EDIT: Probably it's the latest.
Breakin' the sound barrier everyday!
Peace through superior AIRPOWER

Buzzard Viper Driver, 510th FS.
Reaper Eagle Driver, 493d FS.
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#12167486 Mar 14, 2016 at 07:44 PM
Colonel
456 Posts
Thanks.
"No one dared to make a slip, the stranger there among them had the big iron on his hip."
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#12167521 Mar 14, 2016 at 07:58 PM · Edited over 2 years ago
Colonel
456 Posts
I managed to load it up with a2a missiles.

But I cannot get them to fire. I have aa mode and tac is on.

Edit: I think I found out why, the radar does not seem to want to lock onto scenario aircrafts.
"No one dared to make a slip, the stranger there among them had the big iron on his hip."
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#12183839 Mar 19, 2016 at 02:19 PM
Captain
240 Posts
How feasible would it be to improve the currently poorly-modelled F-106 Delta Dart?

Various relevant documents and manuals, including some data, may be found here:
Your text to link here...

The current F-106 is in a way a blank slate to which improvements may be added. Also, the airbrakes don't work.

That is BEFORE we get into how problematic the current FDM is. In its current state, it is possible to, by making a carefully scheduled climb, to enter a "superglide" flight regime in which it is possible to fly indefinitely at ~70000ft and mach 2.5-3.3. The performance data from the specified source should allow the creation of a more realistic FDM.

Thanks.
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#12184074 Mar 19, 2016 at 03:38 PM
Colonel
456 Posts
There is so much on my slate at the moment that I will have to say no to that. Same for SAMs.

Cannot speak for others though.

Thats some nice data you have there though!
"No one dared to make a slip, the stranger there among them had the big iron on his hip."
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#12192309 Mar 21, 2016 at 11:26 PM
Captain
240 Posts
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#12192335 Mar 21, 2016 at 11:35 PM · Edited over 2 years ago
Colonel
263 Posts
Here are some more:
http://www.avialogs.com/index.php/en/aircraft/usa/convair/f-106deltadart.html

We still need windtunnel data and engine preformance data for an accurate JSBsim FDM.

Want to build this model together?

-fb237
FB (primary), fb237, USS_FB, <ICAO>_FB, STS-FB (Space Shuttle)
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#12192780 Mar 22, 2016 at 03:15 AM
Captain
240 Posts
Only if I am able to learn along the way. I am not at all familiar with the workings of FG, aside from reading about it on the wiki.

At this stage, does it seem that we will have to use YAsim? What exactly would be required for JSBsim? Please explain as though I know nothing.

Thanks for... so much.
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#12192897 Mar 22, 2016 at 04:27 AM · Edited over 2 years ago
Colonel
263 Posts
Well, If we are going to get the FDM accurate, I recommend we use JSBsim + windtunnel data. That is the best route in to getting an accurate aircraft flight dynamics model (FDM) in FlightGear. Yasim would be horrible for this model, as from what I learned, it doesn't simulate aerodynamics in transonic and supersonic speeds well compared to JSBsim. Read it on the FlightGear forum somewhere. Yasim is great when you have general performance data, but lack windtunnel data. In short, Yasim is more of an approximation (uses 3D model to generate FDM) than anything else, JSBsim is about precision and accuracy (when done properly). I don't mean to offend anybody elses opinion on JSBsim vs Yasim. I just feel JSBsim is the best route.

Anybody have any suggestions?

-fb237
FB (primary), fb237, USS_FB, <ICAO>_FB, STS-FB (Space Shuttle)
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#12192963 Mar 22, 2016 at 05:11 AM
Colonel
456 Posts
Yes.

You can generate a JSBSim like Yasim using AeromatiC++.
But unlike Yasim, afterwards you can go in and modify anything you like. Plus you have the JSBSim system, where you can make nice electrical, hydraulic, fuel systems etc etc.. JSB is really powerful in that regard.
I would avoid Aeromatic 1 and 2 though, AeromatiC++ is much more complete.

There is also Datcom+ Pro, if you want to give it some more effort and spend the money.
"No one dared to make a slip, the stranger there among them had the big iron on his hip."
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#12193305 Mar 22, 2016 at 09:00 AM
Colonel
560 Posts
About future aircraft... I'm working on an advanced tanker for FG, derived form the 707TT, the KC-137R ATAARS (Advanced Air-To-Air Refueling System), would you be interested to add it to the ORF fleet?
Mav
Breakin' the sound barrier everyday!
Peace through superior AIRPOWER

Buzzard Viper Driver, 510th FS.
Reaper Eagle Driver, 493d FS.
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#12193920 Mar 22, 2016 at 01:15 PM · Edited over 2 years ago
Colonel
45 Posts
#12192780 SNOWY1 wrote:

What exactly would be required for JSBsim?



To make a flight model using JSBSim you need to understand how forces and moments act upon a rigid model with six degrees of freedom, and how this is affected by mass and inertia. In simple terms forces cause movement and moments cause rotation. The good news is that JSBSim does most the hard maths for you; and I think it greatly simplifies making a flight model.

Refer to my f14a.xml for an example of how it should be done using wind tunnel data. The aerodynamics uses what's called a coefficient build up method to calculate the forces and moments in X,Y,Z which give you six non dimensional coefficients 3 for the forces and 3 for the moments, usually CFX, CFY, CFZ (forces) and CML, CMM, CMN (moments).

YASim is best suited to subsonic civilian, and transports, where most of the flying is landing, cruise and takeoff. A YASim has two solution points; anything outside of this is going to be wrong by varying amounts. The way that stall is implemented in YASim is also not suited for high performance aircraft, the F-14 and F-15 don't stall in the traditional sense, and you'll regularly see high alpha values in tight turns even at high speed. It's worth reading the Mirage-2000 YASim FDM (m2000-5-yasim.xml) to understand the limitations and workarounds that are required for this aircraft. Ultimately YASim hurts the realism and dynamics of the aircraft.

JSBSim is really a generic modelling system that is tailored for vehicle simulation with a bias towards flying.

My view is that you need to use aerodynamic table lookup to get a good flight model. Ideally get some wind tunnel data, I know that getting wind tunnel data isn't easy. If you can't get windtunnel data then start with windtunnel data for something of similar geometry (e.g. F-14 for a Tornado, Saab GAM for a Eurofighter). With hard work it is possible to get a representative model without real data.

Once you understand the coefficient build up it becomes possible to tune the aerodynamics and add pretty much anything (which you can't do in YASim).

I'm confident that you could get FAA Level D certification for a JSBSim model (given the right aerodata).

For the F-106, as with a lot of older US aircraft there are some good reports available. This isn't the case for most other countries, although Saab did publish their Generic Aerodata Model (similar to JAS39).

For F-106 windtunnel / flight test data a brief search reveals.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19870017425.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19860015232.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19870012422.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900003243.pdf


Also worth looking at the F-102 NACA FM SL55Dl9

I thank the good folks at NASA and AFWAL for publishing their wind tunnel data that I used on the F-14 and F-15.

I've only used DATCOM, and last time I looked it wasn't very good at more than 15 degrees alpha, DATCOM+ might be better. I'm currently doing some R&D on OpenVSP - it's looking promising (I used it for the F-15 external tanks). However for a full model I'm estimating about a month of CPU time on my i7-2600. What I'm doing is building an F-15 aerodynamic model and when it's done I can check the numbers against what I already have from the wind tunnel. If it's anywhere close then at last maybe I can make a BAe Hawk model.

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#12195426 Mar 22, 2016 at 09:16 PM
Captain
240 Posts
Why does YAsim necessarily have only 2 solution points? Is the body of data and content linked in this thread sufficient to build a reasonably good JSBsim flight model?

Thanks.
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#12195937 Mar 23, 2016 at 12:09 AM
Colonel
456 Posts
Not sure I understand your second question Snowy.

Mav, we already 'have' Onox's 707s in our fleet. And they crashes us most of the time we see them in multiplayer, I think that needs to be resolved first.
"No one dared to make a slip, the stranger there among them had the big iron on his hip."
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#12196746 Mar 23, 2016 at 08:01 AM · Edited over 2 years ago
Colonel
45 Posts
#12195426 SNOWY1 wrote:

Why does YAsim necessarily have only 2 solution points? Is the body of data and content linked in this thread sufficient to build a reasonably good JSBsim flight model?



AIUI YASim uses the 2 solution points to work out plausible aerodynamics. ref: What is YASim, YASim solutions, and for the mathematicians YASim design notes.

The documents here are a start. It took me weeks of searching, using both Google, bing, NTRS and the references in existing documents to find the documents for the F-15 aerodynamics. Overall the F-15 aerodynamics probably took me 8 weeks, probably because I wanted it to be as right as I could get it.

Aeromatic is probably the easiest way to get a flying JSBSim model as a basis. When using aeromatic you get better results by providing more data.
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#12199126 Mar 23, 2016 at 09:36 PM · Edited over 2 years ago
Captain
240 Posts
Generally, does one start with an aeromatic model and tune it? Sorry, but I am not likely to be of any more real use in finding aerodynamic data. I have no real good sources.

Also, I am making various changes the bad YAsim FDM of the current F-106 as practice to see the effects on the aircraft's behaviour. There are some apparent errors, such as approach fuel being set to 100%. I am not yet making any attempt to improve realism - currently just using it as a learning tool.

Thanks for all the patience.
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