Board index FlightGear Development Aircraft

New historically realistic Sopwith Camel JSBSim FDM released

Questions and discussion about creating aircraft. Flight dynamics, 3d models, cockpits, systems, animation, textures.

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby jam007 » Fri Mar 17, 2017 5:10 pm

Bomber wrote in Thu Mar 16, 2017 8:44 pm:56.18hp
Fuel flow 15.757 gph

These numbers are odd. Fuel flow in gph should be approx. 10% of the hp. Shouldn’t it?
jam007
 
Posts: 477
Joined: Sun Dec 16, 2012 10:04 am
Location: Uppsala, Sweden
Version: 2017.3.1
OS: Ubuntu 16.04

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Bomber » Fri Mar 17, 2017 5:31 pm

I think I know what's happened... I checked for engine management in the xml systems files but didn't consider the Nasal... could be that it's spark fail drop of 5/9ths of the cylinders done in Nasal.
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchel
Bomber
 
Posts: 1934
Joined: Fri Dec 14, 2007 7:06 pm
OS: Windows XP and 10

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Bomber » Fri Mar 17, 2017 5:34 pm

0.0925 gallons a HP hour...

So at 130hp that's 12.025gph....
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchel
Bomber
 
Posts: 1934
Joined: Fri Dec 14, 2007 7:06 pm
OS: Windows XP and 10

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Bomber » Fri Mar 17, 2017 7:10 pm

ok it was the spark drop fail but not in nasal, in the fcs section instead... maybe consider putting it with the engine system xml file ?

Anyway.. retested at sea level 15 deg C

1288rpm
122.8hp
14.73gph

right mag only = 49.8hp @ 14.73gph
left mag only = 21.1hp @ 10.5gph

With your engine you might want to consider a Ve of 0.55 and a BSFC of 0.423

which would give you
130hp
12.04gph

Regards

Simon
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchel
Bomber
 
Posts: 1934
Joined: Fri Dec 14, 2007 7:06 pm
OS: Windows XP and 10

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Bomber » Fri Mar 17, 2017 8:19 pm

Wind tunnel test of this plane reveals...

@ max speed 98kts
AoA = 0.22 degs
Weight of plane = 1571lbs

TOTAL LIFT = 1570.8lbs
Lift_alpha = 1572lbs
Lift_elevator = -1.31lbs
Cl = 0.23

TOTAL DRAG = 261.4lbs
Basic_drag = 257.3lbs
Drag_elevator = 1.12lbs
Drag_induced = 2.98

LIFT to DRAG = 6

Pitch_alpha = -117.28
Pitch_elevator = 112 [closest I could get]

Cl at zero alpha degs = 0.206

Regards

Simon
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchel
Bomber
 
Posts: 1934
Joined: Fri Dec 14, 2007 7:06 pm
OS: Windows XP and 10

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby flug » Sun Mar 19, 2017 12:21 pm

FYI I just released the 2.0delta version of the Camel:

https://github.com/bhugh/SopwithCamel-J ... 0delta.zip

Along with the 4.6delta version of Bombable:

https://github.com/bhugh/Bombable/archive/4.6delta.zip

Major improvements since 2.0gamma:
- Continual improvements to FDM, quite a big improvement since 2.0gamma
- Fuselage shadow (in ALS graphics mode - highly recommended)
- Guns/tracers improved
- Ultra-minimal HUD included, suitable for WWI-era aircraft (copy to Huds & edit preferences.xml to use). The dials are nice & authentic but hard to read; the HUD gives you the same info but makes it accessible in FG.
- Many small bugs fixes, blip & magnetic especially.


Altogether in ver. 2.0:
- Ground contact effects, ground shadow (in ALS mode - highly recommended)
- Rembrandt-ready
- Greatly improved sound design, ground contact, engine, and air effects
- Much improved and refined Flight Dynamics Model, closer to actual Camel performance in a large number of measurable ways
- Greatly improved engine and 'blip' simulation, far closer to engine & magneto operation of the historical Sopwith Camel
- Updated documentation and in-game help for takeoff, landing, taxiing, etc, including several new historical documents and first-hand accounts of flying the Camel
- Minimal HUDs (install in your Huds directory & add to preferences.xml) ideal for WWI-era aircraft
- Crash and damage effects

Documentation needs a bit of freshening up and I'm hoping to incorporate some of Bomber's engine tweaks etc, but this is getting very close to our final 2.0 release.
flug
 
Posts: 218
Joined: Wed Jun 17, 2009 1:06 am

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby flug » Sun Mar 19, 2017 9:53 pm

Bomber wrote in Fri Mar 17, 2017 7:10 pm:Anyway.. retested at sea level 15 deg C

1288rpm
122.8hp
14.73gph

right mag only = 49.8hp @ 14.73gph
left mag only = 21.1hp @ 10.5gph

With your engine you might want to consider a Ve of 0.55 and a BSFC of 0.423

which would give you
130hp
12.04gph


Many thanks, Simon.
flug
 
Posts: 218
Joined: Wed Jun 17, 2009 1:06 am

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby flug » Sun Mar 19, 2017 10:01 pm

Bomber wrote in Fri Mar 17, 2017 7:10 pm:ok it was the spark drop fail but not in nasal, in the fcs section instead... maybe consider putting it with the engine system xml file ?


The deal with this is, turning off one magneto leaves 5/9 cylinders firing, and turning off the other magneto leaves you with the other 4/9 cylinders firing. Gasoline & oil keeps flowing so this gives two power settings but neither affect fuel flow significantly.

In JSBSim it's easy to simulate one of those two magneto settings with sparkfaildrop. That is (supposedly!) set to simulate the 5/9 cylinder setting. But then there is no way (that I know of) in JSBSim to natively simulate the 4/9 magneto setting in addition to the 5/9 setting (you could do one or the other with sparkfaildrop, but not both).

So what I've done is just set a little scale factor in fcs to simply reduce throttle by (about) the right amount when the left magneto is turned off. This plus sparkfaildrop together give us our 4/9 power setting.

The fcs/throttle trick for the left magneto gives a power reduction but additionally cutting the throttle affects the rate of fuel consumption. The power reduction is what we're after but the change in fuel consumption is an unfortunate side effect and something I would fix if I thought I could do it easily . . .

Based on your test neither magneto setting is quite hitting the desired hp outputs but what I've outlined above is the concept & goal, anyway. (I'm not sure if running an engine like this on 5/9 cylinders would give exactly 5/9 of full horsepower, or 4/9 cylinders produce exactly 4/9 of full horsepower, but that's been my target for lack of a more well-documented one.)
flug
 
Posts: 218
Joined: Wed Jun 17, 2009 1:06 am

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Thorsten » Mon Mar 20, 2017 6:25 am

but the change in fuel consumption is an unfortunate side effect and something I would fix if I thought I could do it easily . . .


Simple - switch statement to determine what condition is currently flown, outputting a negative external fuel flow rate designed such that the sum of JSB-sim computed and this rate is the real rate you want to simulate, then let the negative fuel flow drain the tank in addition to the automatic drain.

It's no more than 20 lines to do (well, unless you have a complex fuel system with many valves and cross-feeding...)
Thorsten
 
Posts: 11112
Joined: Mon Nov 02, 2009 8:33 am

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Bomber » Mon Mar 20, 2017 8:38 am

I think a more elegant solution would be to adjust the bsfc to give the desired power leaving the fuel flow untouched.
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchel
Bomber
 
Posts: 1934
Joined: Fri Dec 14, 2007 7:06 pm
OS: Windows XP and 10

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Bomber » Mon Mar 20, 2017 2:39 pm

Something else to look at is the total all up weight for this plane and it's ammo allotment...

What I'm finding from my maths is that with full ammo it's not possible to take full fuel and remain within the weight limits.

and another question slightly tangental... is there a WWI terrain to fly this plane over, with trenches and barrage balloons... a blasted hell of a landscape ?

Regards

Simon
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchel
Bomber
 
Posts: 1934
Joined: Fri Dec 14, 2007 7:06 pm
OS: Windows XP and 10

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Thorsten » Mon Mar 20, 2017 4:19 pm

and another question slightly tangental... is there a WWI terrain to fly this plane over, with trenches and barrage balloons... a blasted hell of a landscape ?


If you have the textures, I can tell you how to convert a strip of terrain into that - it's just a question of allocating materials.
Thorsten
 
Posts: 11112
Joined: Mon Nov 02, 2009 8:33 am

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Bomber » Mon Mar 20, 2017 4:27 pm

Thanks Thorsten,

But at present I'm flat out on plane FDM's so as to have a large and varied hanger of planes demonstrating my alternative method of flight model building that I do..

However that said it wouldn't be a bad thing to simply explain how it might be done to a wider audience in the hope that someone picks it up and runs with it. As there are quite a few terrain modellers here, so I'm rather surprised that this has been attempted already.

Regards

Simon
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchel
Bomber
 
Posts: 1934
Joined: Fri Dec 14, 2007 7:06 pm
OS: Windows XP and 10

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Thorsten » Mon Mar 20, 2017 6:13 pm

However that said it wouldn't be a bad thing to simply explain how it might be done to a wider audience in the hope that someone picks it up and runs with it.


It's actually rather well documented and advertized...

http://www.flightgear.org/tours/terrain-texturing/
http://wiki.flightgear.org/Howto:Regional_texturing
Thorsten
 
Posts: 11112
Joined: Mon Nov 02, 2009 8:33 am

Re: New historically realistic Sopwith Camel JSBSim FDM rele

Postby Alant » Sun Mar 26, 2017 11:26 pm

You asked for some period terain.
I have just pushed a pre-war version of Brooklands airfieldhttps://forum.flightgear.org/viewtopic.php?f=5&t=31766&p=307714#p307714.
This was the airfield where Sopwith aircraft , including the Camel, made their first flights.
The airfield has a large smooth grass play area for taxiing and take-off landing.

Alan
Alant
 
Posts: 913
Joined: Wed Jun 23, 2010 5:58 am
Location: Portugal
Callsign: Tarnish99
Version: from Git
OS: Windows 10

PreviousNext

Return to Aircraft

Who is online

Users browsing this forum: CaptainCrazyAviation and 2 guests