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Robin DR400: JSBSim FDM, photorealistic cockpit / dashboard

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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby Thorsten » Sun Mar 25, 2012 7:44 am

Okay, thanks, the latest version works *great* (I love the GPS...).

How do you get it into an asymmetric stall btw? I tried a few times pulling sharply upwards and then rolling the wings slightly, but that didn't do anything nasty.
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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby jentron » Sun Mar 25, 2012 8:18 pm

F-JJTH wrote in Fri Mar 23, 2012 8:50 pm:EGT is not yet simulated but it comes soon.


Hi, would you mind saying what is wrong with the current JSBSim EGT simulation that you feel it isn't simulated yet? It should be working well in 2.6.

Thank you,

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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby F-JJTH » Sun Mar 25, 2012 10:35 pm

Hi jentron,

Properties are available, just we haven't yet configured instruments. (I speak for EGT and oil-pressure)
Just one question : can we have a "carb-temp" property ? This property would give "carburator temperature"
Oh an other question : which property need to be toggled in order to stop engine when tank valve is closed ? because currently if we close the tank valve, engines still running :(
Or may be we need to create a fuel system as described here : http://wiki.flightgear.org/Howto:_Write ... _in_JSBSim ?

@Thorsten: First of all: currently FDM still under developpement. Have you tried to adjust weight (passenger/luggages) ? A good test would be to add weight in luggage compartment.

Cheers,
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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby dany93 » Mon Mar 26, 2012 11:27 am

Thorsten wrote in Sun Mar 25, 2012 7:44 am:How do you get it into an asymmetric stall btw? I tried a few times pulling sharply upwards and then rolling the wings slightly, but that didn't do anything nasty.

Hi Thorsten,

You're right. Guillaume (a DR400 pilot, and the initial author of this FDM on which I later based my own work) has recently gone over again the JSBSim FDM for a better realism, and I noticed that the asymmetric stall didn't work anymore. I think I have to re-fit the angle of attack for asymmetric stall. I was waiting for the FDM modifications to be almost *finished* by Guillaume to do this, and I hope (I think) I can make it work again after that, hopefully in some days.
If you wish to see what it gives, but on a previous version, I can upload a version on which it works (worked). Of course it will be just to test the asymmetric stall, not on the last version. Just ask here.

Cheers,

Dany
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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby redneck » Tue Mar 27, 2012 1:34 am

I actually learned all about spin recovery with this plane, seeing as it was the only one (aside from the newest P-51D, which I have never been able to get off the ground) that was spinnable. It's actually quite simple, but I suggest you climb to at least 3000 AGL before you try it. You lose altitude MUCH faster than in a normal stall. The easiest way with the old one is to simply cut the power, and then attempt to maintain altitude with pitch until the plane stalls. Even if the wings appear to be level, it will always roll over into a spin when it stalls. Then, just use PARED to recover.

Power off
Ailerons neutral
Rudder full opposite the direction of the spin
Elevator down
Dive recovery

I expect the JSBSim model will be the more realistic one once the asymmetric stall issue is fixed. I'm looking forward to it.

That reminds me. I found an issue with the flaps with the old one. If I ever lowered more than (I think) 2 notches of flaps, then the flaps would cause so much drag that the plane would enter a pretty much unrecoverable stall, even with full throttle and negative pitch. Is this fixed in the new FDM?
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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby Thorsten » Tue Mar 27, 2012 6:59 am

I actually learned all about spin recovery with this plane, seeing as it was the only one (aside from the newest P-51D, which I have never been able to get off the ground) that was spinnable.


I learned spin recovery quite a while ago in an ASK-13 (the Flightgear version doesn't spin, but the real ASK-13 does). Of course, the 'power off' step can be omitted then :D

If you wish to see what it gives, but on a previous version, I can upload a version on which it works (worked). Of course it will be just to test the asymmetric stall, not on the last version. Just ask here.


Thanks for the offer - I'll just wait for it then. I was just curious that I couldn't get it into a spin despite being really rough on the plane.
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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby dany93 » Tue Mar 27, 2012 3:53 pm

redneck wrote in Tue Mar 27, 2012 1:34 am: Even if the wings appear to be level, it will always roll over into a spin when it stalls.

That's rather delicate, but you can have a stall with no spin by keeping the slip skid ball centered before stall (I have rudder pedals). The spin may happen later if you insist too much by pulling on the stick.

I found an issue with the flaps with the old one. If I ever lowered more than (I think) 2 notches of flaps, then the flaps would cause so much drag that the plane would enter a pretty much unrecoverable stall, even with full throttle and negative pitch. Is this fixed in the new FDM?

(It had previously 3 notches of flaps, it now has 2 notches. Anyway, full flaps is the same angle)
That's weird. I do not have that stall with full flaps, flying level with full throttle or at idle in descent.

My tests:
With the previous FDM (before 9 march 2012):
Full flaps,
Flying level at 1000 ft, full throttle: 161 km/h (86.8 kt),
Descent rate with throttle at idle, 130 km/h: -1100 ft/mn.

I can also recover from a stall at idle with full flaps.

With the present FDM (version from 15 march 2012):
Flying level at 1000 ft, full throttle: 156 km/h (84 kt),
Descent rate with throttle at idle, 130 km/h: -1000 to -1100 ft/mn.

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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby redneck » Wed Mar 28, 2012 2:31 am

dany93 wrote in Tue Mar 27, 2012 3:53 pm:That's rather delicate, but you can have a stall with no spin by keeping the slip skid ball centered before stall (I have rudder pedals). The spin may happen later if you insist too much by pulling on the stick.

Obviously, it can't be kept perfectly centered. There needs to be some sort of tolerance for defining whether it is in the center or not. I have a twisting joystick, but I have found that I never use rudder while airborne, except for the sideslip maneuver (when I'm feeling too lazy to go around) or when I'm doing aerobatic tumbles. I'm not a big fan of keeping my head in the cockpit when I'm flying VFR, so naturally, I usually ignore the slip skid ball. I'd be much happier if I could just feel the yaw on my rear end just like how real pilots do, but I don't have the money, space, or all the necessary knowledge and skills to build myself some sort of generic, moving cockpit simulator, and if I did, I'd probably spend it on real flight lessons, unless I'm just overestimating the cost of building a cockpit simulator.
dany93 wrote in Tue Mar 27, 2012 3:53 pm:That's weird. I do not have that stall with full flaps, flying level with full throttle or at idle in descent.

Well, I don't think I've flown it since FG 2.0.0 was current. Perhaps it's been changed since then.
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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby El Flauta » Wed Mar 28, 2012 4:53 am

I have seen a conflict between your crash-detect system and the ELT: when you turn on the ELT, the system starts to send infinite emergency messages even if the aircraft is flying ok, until FlightGear crashes. The problems occurs with the DR400 and my Cessna 337 Skymaster (i'm trying to put your crash system on it)...

Each systems works fine when are alone, but both at same time are like a bomb :oops: If you find a solution for it i'll be grateful, because i don't know how to solve it for myself.

Thanks. Nice plane.
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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby jeep » Wed Mar 28, 2012 9:12 am

is this system on the last version of the cessna 337 ?

try adding
<crashed type="bool">0</crashed>
in Cessna337-set.xml (near line 23, in the tag section <sim>

and change the line

if (getprop("ELT/armed")) {

with

if (getprop("ELT/armed") and n.getBoolValue()) {

in ELTmessage.nas (line 21)
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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby El Flauta » Thu Mar 29, 2012 2:35 am

Thanks! It works now :)

Still needed of some tunning, but FG doesn't crash anymore, and the performance is ok.
For some reason the script sends 8 messages at same time (not only one), but it's something...
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Re: Robin DR400: JSBSim FDM, photorealistic cockpit / dashbo

Postby jeep » Thu Mar 29, 2012 8:35 am

El Flauta wrote in Thu Mar 29, 2012 2:35 am:Thanks! It works now :)

Still needed of some tunning, but FG doesn't crash anymore, and the performance is ok.
For some reason the script sends 8 messages at same time (not only one), but it's something...


i think that is the part of nasal which detects the crash and modify the /sim/crashed value that is to be tuned, but i haven't look at this part ... ;-)

it seems that i haven't the last version of your aircraft ...
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