How To Make Planes for RC Desk Pilot

[rcspaceflight]

Even though I wrote my first article about a year ago and I got to that magical status where my articles get published as soon as I hit the "Submit For Approval" button, I decided to put this on the forum instead of writing out a well thought out article.

This is probably going to be rather scatter brained.

Instead of trying to make a nice, complete, but not too long, video; I'll just post screen shots and try to explain the process of making a plane for RCDP with text.

Weird, complex sentences already. Hopefully it doesn't get too confusing. For you or myself. I'm really good at confusing myself.

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The process of making a plane for RC Desk Pilot starts off with the 3D model. Personally I use Sketchup and the 3D Rad plug in. I've read that the lower the poly count for the .x file the better for RC Desk Pilot. And this is from Davy, the creator of RC Desk Pilot. But the 3D Rad plug in doesn't seem to have any settings so I always export as a Generic DirectX File. Which has a rather high poly count. Which may be bad in the long run when new features are added to RCDP. But it's the only way I know how.

If you want the control surfaces to move in RCDP, you need to export them separately. My Sketchup files usually end up looking like this:

I have the plane without the control surfaces and then all of the control surfaces separate.

After that is saved, then I delete EVERYTHING except what I want to export as a .x file. For the main plane, you want the "point of origin" to be the CG of the plane. This becomes the pivot point / rotation point in the simulator. Use the red, green, and blue lines that extend from the point of origin to your advantage.



The point of origin for the control surfaces becomes the rotation point. For complex control surfaces, like this aileron for a wing that is a little swept forward and at a 4* angle, it's best to keep the control surface set in a position that it will fit perfecting into the hole in the wing. Simply pick an end and make that the point of rotation. Later when setting the rotation line, you can move it to go along the length of the front of the aileron. You cannot rotate .x files in the aircraft editor for RCDP. Everything must be facing forward and at the proper angle now.


I didn't say it earlier, but you have to go up to "Plugins" to use the 3D Rad plugin. Then go down the list to generic DirectX file.


I think that covers what I wanted to point out for the 3D modeling. If you want to know how to actually use Sketchup, there are some great tutorials already. JasonEricAnderson has a great series. Which is what I watched to learn the basics.

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I'm going to post this for now and will start a new entry for the next step.

 

[rcspaceflight]

I noticed that the point of origin lines are hard to see in those photos. But you can click on them to make them bigger and those lines become more clear.

 

[rcspaceflight]

I want to start by pointing out that sometimes you don't/can't get things to line up perfectly.


Hopefully you can see how the elevator isn't flat with the horizontal stabilizer. The only possible way that I could fix this is by changing the point of origin either on the elevator or the plane. Which would be incredibly difficult to get that perfect, so just leave it. Close enough is close enough. You're not likely to ever notice this in the simulator. Actually, for my Profile DC-3, the servo arms are even more horribly off, but since you never get a good look at the servos, or at the right angle, you can't really tell. Just know that the placement of control surfaces are limited in the aircraft editor.

I also want to note that when you are creating planes yourself, they end up getting saved under your computer's "documents" folder. RC Desk Pilot creates a new folder called, well, RC Desk Pilot. This is a separate place from the planes that come with RC Desk Pilot. That folder is probably the one where you saved planes you've downloaded too. The only real difference between those two locations is that the ones in your document folder are always on the bottom of the list of aircraft. RC Desk Pilot reads both folders for planes.

When you select a control surface, it highlights the rotation line. Here you can see how I had adjusted the line to run along the front of the aileron.


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I don't know how much I'd have to explain. The manual that comes with the aircraft editor (which comes with RC Desk Pilot) does a good job of covering the basics. I want to focus on the little things that I've learned. But putting together the 3D model is pretty basic. Can be time consuming, but basic.

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I'll just focus on setting up the flying characteristics.

I think first, after the 3D modeling is done, and after the 3D model in the aircraft editor is set up, is to change the settings to how many channels the plane has.

Under the "Misc" tab, there is an option for whether or not the plane has ailerons. If it's a three channel with rudder, elevator, and throttle, then you turn off the "has ailerons" check box.


If you are making a three channel plane with ailerons, elevator, and throttle, then you have to go to the "Physics" tab, click on the "Flight Parameters" button, and simply turn the "Rudder Effectiveness", which is on top, all the way down to zero.

 

[rcspaceflight]

Ah, the fun part. The flying characteristics.

I like to do the "Dimensions" next.


The heaviest that I have a plane is 2.00Kg. The lightest is 0.50Kg. That is probably all you really want to set the weight at. It seems like the flying characteristics need to be exaggerated a bit. But the weight seems to be a bit sensitive. As far as I can tell, weight counter acts the thrust. The heavier, the slower. The lighter the faster. And yet, with the playing around I did, it seems best to just make the weight somewhere between 0.90 and 0.50. I'm not sure how much it actually matters, but down low like that seems like a good place. You can adjust everything with all of the other settings.

If you're looking for more lift and a longer/better glide slope, you don't get that from the "Lift". You get a longer/better glide slope from adding surface area to the wings. DO NOT bother trying to calculate out the actual surface area of the wings for the plane you're modeling. At least I never did. Again, it seems like the settings need to be exaggerated a bit. For planes like the Baby Blender, since it's a bi-wing, I added surface area to the wings because it seemed logical.

Usually for the vertical area I look at the size of the fuselage and rudder (i.e. the vertical are) of the plane as compared to the wings and set those two accordingly. Don't worry about getting these perfect. I never did. I just did a rough idea, ball park setting.

Just know that wing area is glide slope and vertical area is side lift and rudder stability. (I think.)

After Dimensions, go on to Moments of Inertia.


The .3, .3, .6 is pretty standard. I tried the calculator on the bottom, I'm sure it's great, but isn't always worth using.

The Moments of Inertia sets how much the plane wants to maintain going in the corresponding direction. I think this has the most to do with weight. The heavier the plane, the more it wants to continue a direction when going a high speed. If you want that control direction to be easy to make at high speeds, then lower the Moment of Inertia. If you want the speed to be fighting against the plane, making it hard to turn, then set the Inertia high.

Now onto the Lift.


To delete a point on the graph, you simply right click that point. If you want to add a point, right click the line and a point will be added half way between two points.

The best advice that I have figured out is that if you want the plane to glide really well when it's at level flight, set the point at/near the 0,0 mark, up to .10 of lift at the zero degree mark. Any more, and the plane usually lifts up, the nose starts to go up, when you punch the throttle at level flight. Remember earlier when I mentioned the wing area? if you want the plane to fly straight and level without elevator, set the lift to about, or a little below .10, but if you want a longer glide slope, you have to add wing area.

If you want the plane to sink down when inverted, then you must adjust the two points on the ends of the graph. Those are at the 180* part of the graph, or the upside down plane part. Bring that down to -.05 or so. If you have a symmetrical wing and you want lift when inverted, then bring those two points up to .7 or so. Probably to whatever you have the zero degree lift set at.

Other than those two things, the peak at 45* and the lowest at -45* is pretty standard. I should mention that the lift graph is how much lift is created at any given angle of attack. With the nose up at 45*, you're creating more lift because of the same effects that give lift to the FT Flyer.

Anyways, to re-cap, the most important points on the lift graph is how much lift is created at zero degrees and at 180 degrees. Otherwise some where around 1.0 lift at 45 degrees and 0.0 lift at 90 degrees is a good standard/starting point. If you think you want more lift when the nose is up, then add some. If you want less, then bring the high point down.

Side Lift is similar, but it's how much lift is created when the plane is on it's side. Most planes create some lift while on it's side because of the shape of the fuselage. If you want the nose of the plane to dip down when the plane is on the side, then lower the lift. If you want the plane to fly straight and true, even when it's on it's side, the add lift.

The Drag graph is similar to the lift. But the more drag you add, the slower the plane will be. The drag fights against the throttle. The higher the angle of attack, the more drag is created because more plane is hitting the on coming air. But generally, you want the zero degree of attack drag to be set at zero. The drag is very sensitive. If you set it at about .5, then you'll never get off the ground without super amounts of thrust set to your plane.

Side Drag is the same to the Side Lift as the Drag is to the Lift graphs.

The Flap Graphs only apply if you have flaps on your plane. If you add flaps, you only want slightly more lift and possibly no more drag. Just because of how sensitive the drag can be.

The Propulsion is near to last.


The Max Thrust is the top speed of the plane. The Delay is how fast the plane gets to top speed. But if you want a slow plane with a lot of pulling power, I think you need to add a lot of thrust, but then also add more drag. Because the drag and thrust fight against each other.

Last to set is the Flight Parameters. Really only change this, other than the obvious rudder if you don't have rudder and the dihedral if your plane has dihedral, after you test fly.

To test fly while in the Editor, simply click the check box on the bottom of the Physics tab. It's worth while to note that if you don't have any collision points or landing gear points set, your plane is going to fall straight down under the ground. If you want to test fly before setting any points, just set it as hand launch.

Flight Parameters are all about adjusting the fine details of how much rudder, elevator, and aileron the plane has. The Dampening settings changes how smoothly the plane transitions. Stability is how much the plane wants to stay at level. If you're diving your plane down and quickly pull up, high stability will make the plane go to level and then want to stay there. Low stability, and the plane will quickly do a loop. Then usually nose dive into the ground.

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I think that's actually everything I wanted to cover with the flying characteristics. They're supposed to be pointers after you already have some basic knowledge of the software.


The best thing to do is to adjust one setting to something ridiculous and see how it flies. Then set it to the other extreme and see how it flies. You'll better understand what that setting does.



Any questions, ask. Because I think I covered everything that I wanted to.