Brilliant! Great to see a Gnat being progressed! I love this little jet... known as "The Pocket Rocket".
I had in the back of my mind that after working on the Lighting I'd love to work on the Gnat. So I had already researched it and gathered copies of some of the manuals, please feel free to download for reference to support development: https://scottbouch.com/tmp/gnat-t1.zip (~800Mb)
I have to ask about the cockpit panel layout shown: It it inherited form the Xplane Gnat T Mk.1 model or something put together from a library of parts just to get it going?
As the Gnat T1 was used for training pilots to progress to the Lightning, it shared similar IFIS instrumentation to the Lightning (and Buccaneer). I took this image of the Gnat T1 procedure trainer cockpit at Newark Air Museum back in 2016. Note the T1 panel/interior is dark sea grey.
There are also other similarities to the Lightning such as TACAN, ILS, and the principals of the warning system.
The single seat Gnat F Mk.1 (and HAL Ajeet version) had a very different panel layout (and painted black), wondered if this had been referenced when building the cockpit layout?
Thanks for making the APs available for people. I have the Vol 15 and Vol 16 plus some others but can't re-distribute them. The Vol 1s are good for extra details above the Aircrew Manual.
Well, I made the Xplane Gnat T Mk.1 myself from a blank screen so it's not surprising that it would inherit some stuff :o)
Base-colour wise, (in Models/Interior/Gnat_cockpit_INN.png ) of the T1 it is this
It would be easy to change as it is just the base layer in a Photoshop file. But I'm sure FGUK will adjust it to how they want it.
TACAN is not a thing in X-Plane. To be honest, most people don't even bother with ILS/VOR/DME. Much the same in FGUK, I reckon. The dimmers are where they are because the real ones are too awkward to operate with a mouse. Easy enough with a thumb in the real thing, without even needing to look down. The external lights, start sequence and smoke switches ended up where they are for similar reasons.
To help me understand it, I started with the prototype.
It started off to be a cheap and simple-to-make fighter, one saving was using the landing-gear covers as speed brakes. The landing gear had a first position for "slow down a bit". Consequently. it took off and landed with full speed brakes. Whoever thought of this had no consideration for future flight-sim developers. I got it to work in XP but I haven't thought about it for FG. Pre-T1, the flaps function of the flaperons also operated in synch with the landing gear!
It needed a lot of up-trim for take-off and a fair bit for landing - this is what the green zone is on the elevator indicator in the lower left of the panel. It had elevators but they were locked to the moving tailplane in normal use. In the event of a hydraulics failure, they could be unlocked and operated manually. If you were quick enough to realise the problem and act on it. Here, there is also another developer problem. In XP you can set the elevator/tailplane incidence but in FG YASim decides. that for you. Which is why this gauge is not really functional.
The nosweheel was castering and so the aircraft would be steered by the toe-brakes until there was enough speed for the tail to take over. A curious effect of having two wheels on the nose is that the outside one will tend to lift off the ground in a tight taxi turn. Tricky to model this. The code is in the T1 XP version if anyone wants to take this on.
There's probably other stuff but this is all I have off the top of my head.
From a 2010 visit to, the Historical Aircraft Squadron, Ohio, USA, the (slightly incomplete) Indian built HAL Ajeet cockpit below, is fairly close to the F Mk.1 layout:
I'd suggest there may be some overlap between the Lightning and Gnat T1 development given the similarities, help could be reciprocal.
The Vol1B is brilliant for modelling systems with acccuracy, such as electrical, hydraulic, bleed air, etc.. Plus the mechanical Vol1A also includes a lot of airframe dimensions too.
Yes, as @Scott said on another thread, it is by pilots, about pilots and primarily for pilots. Nevertheless there is some interesting stuff in it. There are numerous reports in the first chapter about issues with fuel limitations. The trim/tailplane/elevators/hydraulics are also a commonly-occurring thing.
4. The tailplane and elevator, normally locked together, are operated by screw jacks, powered by an hydraulic motor; supplies are either from the main hydraulic system or the accumulator. Artificial feel is provided by a feel spring unit, electrically adjusted to eliminate stick forces (see para 11).
5. The gearing between control column and tailplane movement is governed by two different mechanisms in the control system, a cam mechanism and a q-gearing mechanism. An automatic tailplane datum shift is also provided.
6. Cain Mechanism. This is incorporated to vary the tailplane angular movement over the range of stick movement, ie the further the stick is moved aft the greater the angle of tailplane movement per degree of stick movement.
7. Q -Gearing Mechanism
a. The q-gearing actuator jack modifies the output of the cam gearing, varying the angular movement of the tailplane for a given angle of stick movement. The jack is extended by hydraulic pressure and retracted by spring pressure.
b. The actuator is controlled by differential pressure from the pitotstatic system. As speed increases between 200 knots and 540 knots, tailplane movement is progressively reduced: above 0.82M this action is reversed as speed increases.
c. If hydraulic pressure fails, the actuator returns slowly, under spring pressure, to the '200 knots' condition
"Every Gnat pilot will remember the drill, STUPREC,
S - speed below 400kts/.85M, T - trim to the ideal sector, U - unlock elevators, P - power cock off, R - raise guard on standby trim, E - exhaust tailplane and aileron accumulators, C - check operation of elevators, ailerons and standby trim."
from Gnat Boys: True Tales from RAF, Indian and Finnish... by Rick Peacock-Edwards
There isn't a generic brake chute - there are a number of ways it has been done in the past
high drag control surface
nasal control of external force applied at the point of attachment
The 1st is easy, but not accurate
The 2nd is harder - found on the old V2, my Firebee, and Mirage F1 (somewhere...), but accurately models side pull on the drag chute by crosswind forces etc & can be animated properly
The Gnat has been updated by Stuart to have some of the latest shaders, the paint looks excellent.
Glass still needs work, you can't see any MP aircraft, or rain through it from the inside, and from the outside it lets you see directly through the model (presumably the same thing as the inside out issue)
It may be that the glass issue is an effect/shader thing. It might be better to separate the glass components - ie: remove them from the model and have them as separate objects? I could do that if required.
EDIT: cancel my last - the new Gnat_T1_fuselage.ac file has 21,976 differences to my original. The glass files are all at the end of the hierarchy if someone wants to separate them out . . .
PNG files can go that. I removed the PNG from the glass, or though I did. PNG files can have some odd property attached to them ( Alpha channel ?? )which can cause the invisibility cloak.
Yes, all glass is now un-mapped to any texture. The alpha channel in a .png is transparency. Usually - unless the .png is being used as a pbr (physics-based rendering) file. Don't think FG uses these.
Comparing what you have done with the model file, there is no obvious difference to what is in the @VooDoo_daVinci P-38L. I looked at this because I've used it in MP without problems. However, the glass in the P-38L is all double-sided objects whereas my Gnat has separate INN/OUT objects (it's an X-plane thing). Maybe worth trying having only a double-sided version for each?
One issue is that the updated Gnat_T1.xml (with the shaders), is in the root
But the set file calls for it in Models (which is the original):
Moving it into Models at least fixes the internal view - which is a start.
There is also an extra Gnat_T1_fuselage.ac in the root folder which as "gnat_t1" is not ideal for any case-sensitive file systems. I know, this has nothing to do with the glass issues ????
Comments
There will be a place for it in the hanger yes.
Brilliant! Great to see a Gnat being progressed! I love this little jet... known as "The Pocket Rocket".
I had in the back of my mind that after working on the Lighting I'd love to work on the Gnat. So I had already researched it and gathered copies of some of the manuals, please feel free to download for reference to support development: https://scottbouch.com/tmp/gnat-t1.zip (~800Mb)
This zip file contains:
AP101B-1801-15_Gnat-T-Mk1 - Aircrew-Manual
AP101B-1801-16_Gnat-T-Mk1 - Operating-Data-Manual
AP101B-1801-1A_Gnat-T-Mk1 - Aircraft-Servicing-Manual (Mechanical)
AP101B-1801-1B_Gnat-T-Mk1 - Aircraft-Servicing-Manual (Electrical)
I have to ask about the cockpit panel layout shown: It it inherited form the Xplane Gnat T Mk.1 model or something put together from a library of parts just to get it going?
As the Gnat T1 was used for training pilots to progress to the Lightning, it shared similar IFIS instrumentation to the Lightning (and Buccaneer). I took this image of the Gnat T1 procedure trainer cockpit at Newark Air Museum back in 2016. Note the T1 panel/interior is dark sea grey.
There are also other similarities to the Lightning such as TACAN, ILS, and the principals of the warning system.
The single seat Gnat F Mk.1 (and HAL Ajeet version) had a very different panel layout (and painted black), wondered if this had been referenced when building the cockpit layout?
Cheers, Scott
scottbouch.com
Thanks for making the APs available for people. I have the Vol 15 and Vol 16 plus some others but can't re-distribute them. The Vol 1s are good for extra details above the Aircrew Manual.
Well, I made the Xplane Gnat T Mk.1 myself from a blank screen so it's not surprising that it would inherit some stuff :o)
I also made the F.1
https://forums.x-plane.org/index.php?/files/file/82712-folland-gnat-f-mark-1/
which. as you say, has a very different cockpit
Base-colour wise, (in Models/Interior/Gnat_cockpit_INN.png ) of the T1 it is this
It would be easy to change as it is just the base layer in a Photoshop file. But I'm sure FGUK will adjust it to how they want it.
TACAN is not a thing in X-Plane. To be honest, most people don't even bother with ILS/VOR/DME. Much the same in FGUK, I reckon. The dimmers are where they are because the real ones are too awkward to operate with a mouse. Easy enough with a thumb in the real thing, without even needing to look down. The external lights, start sequence and smoke switches ended up where they are for similar reasons.
To help me understand it, I started with the prototype.
https://forums.x-plane.org/index.php?/files/file/82116-gnat-prototype/
It started off to be a cheap and simple-to-make fighter, one saving was using the landing-gear covers as speed brakes. The landing gear had a first position for "slow down a bit". Consequently. it took off and landed with full speed brakes. Whoever thought of this had no consideration for future flight-sim developers. I got it to work in XP but I haven't thought about it for FG. Pre-T1, the flaps function of the flaperons also operated in synch with the landing gear!
It needed a lot of up-trim for take-off and a fair bit for landing - this is what the green zone is on the elevator indicator in the lower left of the panel. It had elevators but they were locked to the moving tailplane in normal use. In the event of a hydraulics failure, they could be unlocked and operated manually. If you were quick enough to realise the problem and act on it. Here, there is also another developer problem. In XP you can set the elevator/tailplane incidence but in FG YASim decides. that for you. Which is why this gauge is not really functional.
The nosweheel was castering and so the aircraft would be steered by the toe-brakes until there was enough speed for the tail to take over. A curious effect of having two wheels on the nose is that the outside one will tend to lift off the ground in a tight taxi turn. Tricky to model this. The code is in the T1 XP version if anyone wants to take this on.
There's probably other stuff but this is all I have off the top of my head.
Cheers
Thanks Warty,
From a 2010 visit to, the Historical Aircraft Squadron, Ohio, USA, the (slightly incomplete) Indian built HAL Ajeet cockpit below, is fairly close to the F Mk.1 layout:
I'd suggest there may be some overlap between the Lightning and Gnat T1 development given the similarities, help could be reciprocal.
The Vol1B is brilliant for modelling systems with acccuracy, such as electrical, hydraulic, bleed air, etc.. Plus the mechanical Vol1A also includes a lot of airframe dimensions too.
scottbouch.com
Would love to add it to the hangar, thank you gentlemen for all the contributions!
I'll get it uploaded today.
Alex
Cheers, Alex.
I'll use it for my next FlightNight if it is available.
Gnat is now released in the main hangar, will go through doing the public bits throughout the day.
Thanks for your patience!
Does anyone know how accurate the model is on fuel consumption?
At 415kts and 6,000ft it was burning through 12 gallons a minute, giving a 18 min endurance.
At a more respectable 15,000ft and 300kts it gave 5 gallons a minute and a 40 odd minute endurance. Is that accurate?
Not too sure, I’ve done flights that are similar to what the reds do and I’ve run out of fuel, but I’m always full throttle so could just be me.
Seems realisticish.
CJ
OrbitalMartian
Callsigns: G-ORBI
Gnat T.1 Flight Reference Cards found here, has useful info on all sort of things:
https://hang-out.co.uk/uploads/Gnat-T-Mk-1-FRCs.pdf
Includes approach speeds at different weights, and fuel use in climb in different states - should be useful to check against
AP101B-1801-16_Gnat-T-Mk1_Operating-Data-Manual.pdf that Scott provided has lots of Operating-Data in it :o)
BTW, TSFC in the Gnat YASim FDM is unspecified - default YASim TSFC is 0.8
Bristol Orpheus 803 is known to be 1.08, but the one used in the Gnat might be a bit lower as it has lower thrust, but probably around 1
nice
I've been reading today a book called "Gnat Boys". It just became available as an ebook on Scribd
https://www.scribd.com/read/600265297/Gnat-Boys-True-Tales-from-RAF-Indian-and-Finnish-Fighter-Pilots-Who-Flew-the-Single-Seat-Training-and-Fighter-Aircraft
Yes, as @Scott said on another thread, it is by pilots, about pilots and primarily for pilots. Nevertheless there is some interesting stuff in it. There are numerous reports in the first chapter about issues with fuel limitations. The trim/tailplane/elevators/hydraulics are also a commonly-occurring thing.
That blog has some fantastic scanned documents! Browse the rest:
https://hang-out.co.uk/uploads/
Cheers, Scott
scottbouch.com
Interesting info from https://hang-out.co.uk/uploads/Gnat-T-Mk-1-Aircrew-Manual.pdf on the tailplane control mechanism:
Tailplane and Elevator
4. The tailplane and elevator, normally locked together, are operated by screw jacks, powered by an hydraulic motor; supplies are either from the main hydraulic system or the accumulator. Artificial feel is provided by a feel spring unit, electrically adjusted to eliminate stick forces (see para 11).
5. The gearing between control column and tailplane movement is governed by two different mechanisms in the control system, a cam mechanism and a q-gearing mechanism. An automatic tailplane datum shift is also provided.
6. Cain Mechanism. This is incorporated to vary the tailplane angular movement over the range of stick movement, ie the further the stick is moved aft the greater the angle of tailplane movement per degree of stick movement.
7. Q -Gearing Mechanism
a. The q-gearing actuator jack modifies the output of the cam gearing, varying the angular movement of the tailplane for a given angle of stick movement. The jack is extended by hydraulic pressure and retracted by spring pressure.
b. The actuator is controlled by differential pressure from the pitotstatic system. As speed increases between 200 knots and 540 knots, tailplane movement is progressively reduced: above 0.82M this action is reversed as speed increases.
c. If hydraulic pressure fails, the actuator returns slowly, under spring pressure, to the '200 knots' condition
"Every Gnat pilot will remember the drill, STUPREC,
S - speed below 400kts/.85M, T - trim to the ideal sector, U - unlock elevators, P - power cock off, R - raise guard on standby trim, E - exhaust tailplane and aileron accumulators, C - check operation of elevators, ailerons and standby trim."
One thing missing from this FlightGear version is the brake-chute. I'm guessing that is something that is set in YASim ?
There isn't a generic brake chute - there are a number of ways it has been done in the past
The 1st is easy, but not accurate
The 2nd is harder - found on the old V2, my Firebee, and Mirage F1 (somewhere...), but accurately models side pull on the drag chute by crosswind forces etc & can be animated properly
The Gnat has been updated by Stuart to have some of the latest shaders, the paint looks excellent.
Glass still needs work, you can't see any MP aircraft, or rain through it from the inside, and from the outside it lets you see directly through the model (presumably the same thing as the inside out issue)
It's here if anyone wants to make the changes:
https://fguk.doghouselabs.dev/FGUK/Gnat_T1
I can take a look at the glass, see if I can fix it, no promise and I’ll let y’all know if I can’t :) my brain is tiny after all.
CJ
OrbitalMartian
Callsigns: G-ORBI
It may be that the glass issue is an effect/shader thing. It might be better to separate the glass components - ie: remove them from the model and have them as separate objects? I could do that if required.
EDIT: cancel my last - the new Gnat_T1_fuselage.ac file has 21,976 differences to my original. The glass files are all at the end of the hierarchy if someone wants to separate them out . . .
More on the glass: it even hides your own airframe - not just others over MP. Weird!
PNG files can go that. I removed the PNG from the glass, or though I did. PNG files can have some odd property attached to them ( Alpha channel ?? )which can cause the invisibility cloak.
Yes, all glass is now un-mapped to any texture. The alpha channel in a .png is transparency. Usually - unless the .png is being used as a pbr (physics-based rendering) file. Don't think FG uses these.
Comparing what you have done with the model file, there is no obvious difference to what is in the @VooDoo_daVinci P-38L. I looked at this because I've used it in MP without problems. However, the glass in the P-38L is all double-sided objects whereas my Gnat has separate INN/OUT objects (it's an X-plane thing). Maybe worth trying having only a double-sided version for each?
Warty the inner glass is configurable for the rain effect. Stu can make it.
The shaders are in the effect folder. But probably Stu forgot to activate the shader.
One issue is that the updated Gnat_T1.xml (with the shaders), is in the root
But the set file calls for it in Models (which is the original):
Moving it into Models at least fixes the internal view - which is a start.
There is also an extra Gnat_T1_fuselage.ac in the root folder which as "gnat_t1" is not ideal for any case-sensitive file systems. I know, this has nothing to do with the glass issues ????
The GIT thing does not work on my PC and I am trying to upload things manually.