P-47 Progress Thread

One of the recurring issues we deal with when delivering modern aircraft is re-rigging the flaps to eliminate a rub condition discovered during the acceptance flights. Getting a uniform tight fit between the flap and the wing without making contact when it deploys appears to be more of an art than a science. Unlike our 3D models, real aircraft tend to bend and twist when you fly them for the first time.
 
(Thanks :redface-new:)

A short question regarding reading blueprints: Does anyone know what the abbreviation "RRL" means?
It has to do with reference lines, like "JRL" being "Jig Reference Line" and "WL" being "Water Line". So the last two letters probably are "Reference Line" but what could the first "R" possibly stand for? This particular line can be found forward of Spar#3 (but is not Spar#1, the main spar, or Spar#2).
 
Frosty said:
(Thanks :redface-new:)

A short question regarding reading blueprints: Does anyone know what the abbreviation "RRL" means?
It has to do with reference lines, like "JRL" being "Jig Reference Line" and "WL" being "Water Line". So the last two letters probably are "Reference Line" but what could the first "R" possibly stand for? This particular line can be found forward of Spar#3 (but is not Spar#1, the main spar, or Spar#2).
Click to expand...

Rudder Reference Line?
 
swpierce said:
Rudder Reference Line?
Click to expand...

Thanks, good try!
But considering the location and orientation of the line (forward of the trailing edge and probably perpendicular to the fuselage) it seems unlikely. The trouble is that the line itself isn't shown on the blueprint. It is referenced to as being x inches forward of a certain point near the trailing edge of the wing... (actually, it's the other way around, of course: the point I am trying to locate is x inches aft the "RRL". But to find and place parts correctly I need to know what "RRL" means). If anyone wants to have a look, I could upload the drawing or PM it...
 
Since it's defined as an offset from a known feature I'd guess Relative Reference Line.

The other option is a Radius Reference Line related to the trailing edge Ellipse Curve.
 
Hi all,

The flap mechanism is coming along reasonably well: Due to the complexity of the system I have used key frame animations instead of the stock rotation ones, using 0-100 key frames (fully up to fully down). It really shows how intricate the system was because I had to use 7 keyframes to make the system follow the mechanics dictated by the geometry of the system.

To try and see if it is any life-like, I have temporarily textured the flap with a stencil that apparently could be found on some P-47s. It's one with black lines and numbers indicating 0, 10, 20, 30 and 40 degrees of flap - you may have seen it on plastic modeling decal sheets. As the P-47 didn't have a 'flap gauge', the pilot was supposed to determine the amount of flap by looking at the lines becoming visible from under the trailing edge of the wing.

According to the SDK, flap entries are giving in degrees of flap. Currently, the flap section in the stock .cfg has 5 entries: 0, 10, 20, 30 and 40 degrees of flap. However, this does not coincide with the stencil or the geometry of the system. So, as part of this experiment, I entered the key frame numbers that give 10, 20, 30 and 40 degrees of flap in the .cfg (flap deployment measured as a rotational angle of the actual flap mesh in gmax). To my surprise things work out perfectly! Key frame 68, 93, 97 and 100 give 10, 20, 30 and 40 degrees of flap. The snag seems to be the flight behaviour: it is markedly different from the original entries in degrees, giving rise to the idea that my key frame entries are still read as degrees.

My question is: how does animating with key frames relate to the flap section entries in the aircraft.cfg? Or put differently: How can I get my 10, 20, 30 and 40 degrees of flap in the aircraft.cfg using key frame animations?
I have used these tags for the all the mesh parts involved:
l_flap_key_1
l_flap_key_2 etc.
 

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Wow! What detail!

For the FM to work out right I think you could use the scalers in the flap section of the cfg.

lift_scalar = 1
drag_scalar = 1
pitch_scalar = 1

are what they normally are. However, since 100 using keyframe needs to give the same effect as 40 did with simple rotation, you just scale the aerodynamic effects down. 40 / 100 = 0.4 so your scaler values should all be 0.4 and all should be back to normal. That is, if I've understood your problem correctly.

EDIT: Oh wait, this won't work. I didn't look at the lower values. If they were a percentage of degree rotation they would work, but they clearly aren't. I don't know if there is a straightforward way of doing this with stock CFS3 capability, maybe on of the gmax experts can weigh in. It would be a simple matter with an RS module script though.
 
i suspect the SDK is not correct. I think frame 100 is use for full flap which is 40 degrees in your case.

beautiful detail.
 
sdsbolt said:
i suspect the SDK is not correct. I think frame 100 is use for full flap which is 40 degrees in your case. ...
Click to expand...

I just realised that there is a flap gauge ingame: When pressing F5, the HUD displays the % of flap extension!

This leads me to believe that the SDK is right but that the info only applies to pure rotational animation names (stock application of "l_flap", in this case). When using key frames ("l_flap_key") in the aircraft.cfg, the key frames are read as a percentage of flap extension in the HUD, keyframe 0 being 0% flaps and key frame 100 giving 100% flaps. This accounts for the altered flight behaviour, as key frame 68 equals 68% of flap extension, while the mesh only shows 10% of flap rotation. I don't know how to correct this, but Daniel might have a point in suggesting using the scalars. This, unfortunately, is beyond my knowledge.

I'll review my animations but in the mean time, I am open to suggestions to solve this problem.

Right now, this is the current state of affairs:
key frame 68 = 10° of physical rotation of flap mesh = 68% of flap extension ingame -> should be equal to 10° of flap (flight behaviour)
key frame 93 = 20° of physical rotation of flap mesh = 93% of flap extension ingame -> should be equal to 20° of flap (flight behaviour)
key frame 97 = 30° of physical rotation of flap mesh = 97% of flap extension ingame -> should be equal to 30° of flap (flight behaviour)
key frame 100 = 40° of physical rotation of flap mesh = 100% of flap extension ingame -> should be equal to 40° of flap (flight behaviour)

Maybe there's something I can do with the naming of parts or the hierarchy...
 
I'm probably just displaying my ignorance here, but perhaps having a dummy part using the l_flap tag could be added in a way that is tied to the keyframe somehow?
 
That gave me an an idea, Daniel.

And I think I might have been an *ss :icon_redface:: I realised that I got here by using the key frame number distribution taken from the first P-47 model I created :banghead::banghead:. That was key frame 0, 25, 50 and 100 to give 0°, 20°, 30° and 40° of flap extension. With this model I started of using the same 25 key frames distribution and added some extra key frames to keep the geometry of the system intact. But there's absolutely no reason to use this distribution of 25 frames. I can also animate the system with key frame 10 giving 10° flap extension, key frame 20 to give 20° etc. The speed at which the mesh moves between the 4 flap settings may differ but that might be acceptable.

I'll try this and report back later!
 
I'm certainly no genius...
icon_redface.gif
.
The basic thought of dividing 100% of flap extension into four settings with 25 key frames each was alright after all, I just had to start with the 10°, 20°, 30° and 40° rotation of the flap mesh and then match the mechanics of the extension system to those positions - not the other way around, duh... Inverse kinematics, anyone?

I say: "Done!"
 
Yep. That's exactly how I remember it being done. Any of the animations in gmax must be 0-100.

Flight model, the airfile, has flap entries in it, for the total degrees, how many positions, and the drag effect at 100% (40 degrees).
 
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