North American RA-5C Vigilante

[John Young]

I volunteered to make the RA-5C Vigilante that was suggested elsewhere on the forum and have opened this topic to keep it with my packages to make finding it at a later date easier.

I've done most of the base modelling and a huge amount of animation, including a nose-fold (not shown):







The more I read about the aircraft, the more I find it interesting. The aircraft has no ailerons because of the large flaps, but a series of spoiler-deflectors in the wing. They work in opposing pairs on the upper wing and lower wing, with one device hinged on the leading edge and the other on the trailing edge so the air flow is forced through the appropriate wing for turning. For landing all the devices are raised or lowered (top and bottom) to 78 degrees to act as spoilers.

I think this is right, but since I've never modelled it before and pictorial information is quite sparse, I'm not totally sure:



If anyone has any knowledge of this system, could you advise if I have it right please?

John

[Victory103]

I have a few books on them, will look. Model looks fast standing still now.

[Firebird]

That does seem like a novel system. Have not heard of that before, which doesn't mean to say that it is not accurate.

What was common in combat aircraft from around that time period was the ailerons on one wing would drop and the spoilers on the top of the other wing would go up. Increasing the lift from one wing and decreasing it on the other.

I will have a look to see if I can find out anything definite on the A-5.

[hschuit]

I would simplify the spoiler/deflectors, 99% of the AI models I have seen do not have animated ailerons, only spoilers. For the Viggie that would mean you only animate the 2 spoilers on top of the wings to make them go up during the final approach.

Here is a screenshot of the Alphasim flyable model with spoilers up:

[John Young]

Thanks Henk. I'm not intending animating the ailerons for flight, just the spoilers/deflectors for landing - two above each wing and two below (I think). I don't think they are deployed on the real thing on the approach, only when the nose wheel touches down.

John

[hschuit]

It looks like Alphasim model has simplified spoilers, I just loaded the old Kaz Ito model and that one has 12 spoilers/deflectors animated when I hit the spoiler key (3 on top of each wing and 3 on the bottom).

[expat]

Exterior model looking good John. One thing - I have an in depth book on the RA-5C and think I have read everything ever available online on this beguiling aircraft - in operation it almost never carried the wing tanks as it carried more than enough fuel on board for its missions and this also is one of the reasons it was often the last or nearly last vs other aircraft types to land during carrier missions.

[hawk_sh]

These previews look awesome!


Regarding the tanks:
According to the book "RA-5C Vigilante units in combat" these tanks were never used operationally on the RA-5C.
"Because of the tank's weight and drag, less than a quarter of the fuel they housed added to the jet's range, the rest being burned while carrying the tanks themselves"

Will you add the flasher pod (usually carried on the starboard wing) as an option?

[TimC340]

The Vigilante definitely didn't have ailerons, and I think your interpretation is essentially accurate, John. The spoiler deflection to apply bank would be proportional to the control input, and for that purpose would likely be limited to around 45 degrees of deflection (the 78 degrees figure would only be for lift-dump/airbrake application). The reverse-flow spoilers are mechanically linked to the conventional ones, and deploy whenever the normal spoilers are deployed.

This quote from Tailspin (see here):

"There were two sets of spoiler, slot, and deflector on each wing (and no ailerons). The deflector was hinged on its aft side so it directed air into the slot; the spoiler was hinged on its forward side to open the slot for the deflected air to escape. One set raised that wing. The other set lowered it. The inboard set took up more of the span than the outboard set, presumably to equalize the rolling moment. If you look closely at the comparison pictures of the A3J and RA-5C above, you'll see two different roll-control configurations, one to roll left and one to roll right. I've added an illustration of the spoiler/slot/deflector.

Speed brake actuation opened all four sets of roll controls simultaneously. Roll control was then accomplished by partially closing the opposing sets, reducing speed brake effectiveness."

Edit: just noticed that you have the inboard and outboard spoilers acting in opposition. They don't; they act in unison. So both upper surface spoilers raise at the same time, though they may raise at different rates and angles. This system is a direct predecessor of what is used on almost all modern airliners, though modern fly-by-wire gives a far more nuanced and adjustable control algorithm.

More info here. The small panel is an extract from the Technical Manual, which is about as authoritative as you're going to get!

Further Edit: it would appear I'm wrong and you're right - the inner and outer spoilers do in fact act in opposition. The outer spoilers give the initial roll input and the inner spoilers increase the roll rate if demanded.

[John Young]

Thanks Tim, that was an interesting puzzle. I think between the cutaway drawing of the aircraft that was in the information Giorgio sent me, that first got me thinking, the information Steve sent me this morning and the reference made by Henk to the Kas Ito model (now observed), I think I have the spoiler/deflectors right. It was always my intention to divide the long spoilers into two to make 3 devices top and bottom of each wing, but to do this on the texture rather than incur two more draw calls. I've got enough of those already.

Thanks Hartwig for the information about the fuel tanks. That would explain why there are so few photos around with them carried, although the plans I'm working from do show them. I'll drop the tanks I think then. I'll add the photo-flash-pod as an option, as you suggest, instead. I think they were circa 1966 but I don't know for how long after. Crews didn't like them in combat because they gave the aircraft's position away to ground gunners.

Between the 3 books I now have, I have a wealth of paint schemes to consider. The trick might be to try and work out which ones were contemporary in the period 1974-1980 when the aircraft were at Key West, when not embarked. Maybe I should exercise some poetic license. I think the very later years had only black markings on the tails. It would be a shame not to paint some colour.

John

[jetpilot1980]

If anyone has any knowledge of this system, could you advise if I have it right please?

John

This may be a bit overkill but here is something that may be helpful in your quest:

https://www.docdroid.com/GxkZXeu/north- ... ersion-pdf

You may have to download and save it as it does not display well in just a web browser...

[John Young]

Wow, what a document - packed full of detail with some gems in it. I found the deflection angles of the horizontal stabiliser for parked and braking (both are animated in the model) and another thing that's eluded me, the position of the lower anti-collision (beacon) light. I knew where the top one was, but I couldn't find the bottom one and assumed there wasn't one. Both are retractable in the real thing. There's also a description of the spoiler/deflectors that confirms the configuration.

The ejection sequence graph is interesting. 1.95 seconds to seat separation after pulling the handle. That's quick, but I don't know what the norm is.

Thanks for that one.

John

[expat]

This is I think the MAIW NAS Key West KNQX in P3Dv4.5. All looks OK re elevation, coast line and other common airport problem areas, with the important exception of no buildings. I might fool around adding some with ADEX and post progress.

[expat]

Er, scratch that re coastlines - it's going to be some more work than adding buildings.

[TimC340]

If anyone has any knowledge of this system, could you advise if I have it right please?

John

This may be a bit overkill but here is something that may be helpful in your quest:

https://www.docdroid.com/GxkZXeu/north- ... ersion-pdf

You may have to download and save it as it does not display well in just a web browser...

That's my reading for the turbo trainer tomorrow sorted!

I just had a quick peruse, and it's interesting to see what this earliest attempt at FBW does compared to the far more sophisticated versions I'm used to.

The ejection separation time you quote John seems about right - the contemporary Martin Baker MkIV seat had 0.5 sec delay for drone deployment and then 1.5 seconds for seat separation.

[jetpilot1980]

Spent more than my time reading flight manuals... Honestly, twisted it may sound I took a liking to them and started reading them for fun even if wasn't currently flying that particular type, just to see the variations on aircraft systems. At the end of the day most aircraft are fairly similar with little twists, and changes in numbers..

[TimC340]

This is I think the MAIW NAS Key West KNQX in P3Dv4.5. All looks OK re elevation, coast line and other common airport problem areas, with the important exception of no buildings. I might fool around adding some with ADEX and post progress.

This is the MAIW KNQX in P3Dv5.3. The only thing that's been done is the buildings have been converted to P3Dv4.4. There's the typical v5 problem of default buildings appearing (easily sorted), but it works ok as far as I can see. I don't actually see a problem with the coastlines either - all of the airfield boundaries appear to be landside of the P3D coasts.

[expat]

Why are the buildings missing then in P3Dv4.5?

[TimC340]

Firstly, the source files that include the buildings must be available to the sim. If you've brought the FS9 airfield into ADE then exported it in P3Dv4 format, you may only have the ADEP4 and OBJ files. The OBJ file is simply obect placements; it doesn't include the objects themselves. For that, you need the buildings libraries as well, and ideally they should be converted in Model Converter X to P3Dv4.4 format (though converting to FSX may sometimes be ok for P3D). So your airfield folder should have at least the following files:

FLOLS.bgl
Key West Object Library.bgl
KNQX_ADEP4_XXX.bgl
KNQX.ADEP4_XXX_OBJ.bgl

The airfield background is the stock one, I believe (I certainly didn't make one). You also need the texture folder from the MAIW airfield. It contains all BMP files, which I converted to DDS, but there's no real need to do that. You may also need the MAIW Global Object libraries installed to get some of the objects on the airfield, and ideally you have the EZ Scenery objects that are referred to in the files Key West EZ_Objects Placement and Key West EZ_Objects Shrubs. I don't have these.

Incidentally, the road that appears to go across the southern lagoon can be deleted - it doesn't exist in real life.

[expat]

Thanks for the prompt reply. I think I have now messed things up. Getting compiler/parse errors now when I try to compile - and it now won't compile. Weirdly, I downloaded a fresh install of the airport from MAIW library here and it still get these errors.

Here is what is in my P3Dv4 addon scenery/MAIW Key West NAS (KNQX)/scenery folder:



This is what it should look like - at least how it was back when I had FSX: