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How can I make an airplane in FS One fly like my own airplane? My airplane is smaller (or bigger) than the one in the sim, and I want to change the Tx settings to my own dual rates, etc.

Versions: V1 and V2

  • Sit back. This is a long one. But in FS One it can take less than a minute to make the airplane tweaks. The discussion below is all about what few things need tweaking and why.
  • Let’s use the Edge 540 as an example. Suppose you have a 25% Edge 540 model in real and you want to make the Hangar 9 Edge 540 33% sim model fly like your smaller version. Although 25% is not that far away from 33%, it’s a huge difference when it comes to how the airplane looks and handles in the air.
  • When people watch airplanes fly, they get a sense of speed, but it’s not speed in mph. Take a jet transport high over head. It’s impossible to deduce how fast it’s flying in mph just by looking up. In fact, it might even appear slow as compared with a model airplane if the model were high up and more or less looked the same size in the sky. In this case, the model would look like it’s flying faster. (Think about your experience with smaller planes. They really zip around!) The sense of speed that a pilot sees is based on not mph, but instead how many wingspans the airplane travels in a given amount of time. In a sense, the RC pilot on the ground perceives a “relative speed” which is in fact relative to the size of the airplane – the more wingspans traveled in a given amount of time the faster it will look. To quantify this relative perceived speed, something called the square-cube law can be used to show this very effect. In can be shown that if the wingspan of the larger plane is twice the smaller, then the time it takes the larger plane to travel one wing span is 41% longer than the smaller. So although the larger plane is actually flying 41% faster, it looks 41% slower. That is a big difference! A 25% Edge is not going to look and fly like a 33% Edge. To get around this fundamental problem of size, FS One includes a Scaling Wizard. Any airplane in the sim can be resized and the physics is scaled automatically.
  • Step 1: Resize the airplane to match your own. In the Airplane Selection window, pick the airplane that you want to change, and click “Copy” to make a copy of the airplane. Then click “Edit” to get into the Aircraft Editor window. You can do a lot here, but let’s fast forward to the Scaling Wizard buttons – the last two menu items on the page. The first of these is the “Scaling – Size/Wgt” page. On this page in the Aircraft Size section, set the wingspan to match your own model. Optionally, the percent change can be given. In going from a 33% scale model down to a 25% scale model, the original Hangar 9 model needs to shrink down to 75.7% (=.25/.33) of its original size in this example. So instead of giving the span, 75.7% can be entered to downsize the original model.
  • The relative speed mentioned above depends on the physical size of the plane as well as the physical speed of the airplane. In this scaling approach, the main determining factor that governs the physical speed is the wing loading, which is aircraft weight divided by the wing area, e.g. units of oz/sq ft. With the wing span set and the wing loading the relative speed as perceived by the pilot is set.
  • Step 2: On the “Scaling – Size/Wgt” page in the Weight Characteristics section enter the wing loading. If that’s not known, then enter the weight instead. In other words, enter one or the other, but wing loading is the better one to use.
  • The next big thing are the control throws. In FS One, the H9 Edge 540 33% is setup to have large control throws for 3D flying. These maximum control throws are activated only when in the “3D Rates” Flight Mode. The Flight Modes are controlled by the TacCon three-position switch. For the Edge with the TacCon Tx setup, the three modes are: “Low Rates”, “Snap Mode”, and “3D Rates”. In high rate mode, “3D Rates”, the control throws are setup to be 40 deg for rudder, 50 deg for elevator, and 42 deg for ailerons. Setting these values to match your own real airplane can be done by going into the Aerodynamics menu of the editor.
  • Step 3: Set the maximum control surface throws in degrees to your own preference. On the Scaling Wizard window, click on the Aerodynamics menu item. Use the scroll bar to slide down to the Joystick section (yellow text). Click on the text for the surface that you want to change, e.g. “ElevRK” for the right elevator. A description of the item will then appear below along with the Current and New box. Read the description, enter the New value and click Apply. Adjust the others to your preference.
  • That finishes the major changes to the airplane that affect the flying. With those changes above that take all a minute or less, that’s enough to have an airplane fly like your own. Beyond this there are FS One transmitter tweaks that can change the settings to make it feel like your own.
  • Dual Rates! Flight Modes! What are they? The FS One TacCon controller uses the switches to control Flight Modes. When the three position switch is moved, it changes the Flight Mode. On the Edge 540, the three Flight Modes are “Low Rates”, “Snap Mode” and “3D Rates”. On a conventional airplane like the C182, they are called “Low Rates”, “Med Rates” and “High Rates”. Just like the names imply, “Low Rates” move the control surfaces less and “High Rates” move them more. The rates for the Flight Modes are set by editing the Transmitter just like in real – you’d edit the transmitter, not the airplane.
  • Expos! What are they? First it’s important to cover some fundamentals of aerodynamics in the high angle of attack post-stall regime of flight. As an airplane is slowed down by pulling up on elevator, the “feel” is more or less “linear”. In other words “twice” the pull might produce “twice” the amount of pitch up. So there’s pretty much a one-to-one correspondance and it feels “right”. Things are all in quote here because this discussion is a bit subjective, but nevertheless is it still quantitative to some degree. When the angle of attack starts to get high, the airplane can stall. It’s in this regime that things start to get “nonlinear”. It might take double or three times the stick throw to get out the desired response. The decay in the response is a result of stall, or separated flow. To some pilots, the necessarily larger stick input in the high angle of attack stalled state might feel like “poor” handling qualities. And this is where “expos” enter the picture. Adding in expos is like adding in a “linearizer” to the aerodynamics. To some degree, expos make the airplane feel more “linear” in high angle of attack post-stall flight. Expos in effect make the control surfaces move a lot more at the extreme stick positions. In other words, at the extreme stick positions, twice the stick push might result in four times the control throw. This extra control surface throw in turn produces a larger aerodynamic response and compenstates for the decay in aerodynamic performance (lift) in the high angle of attack state.
  • Amount of Expos. Different pilots prefer different amounts of expos. Also, the preferences change depending on the Flight Mode. Some pilots fly “3D” with zero expos. Most pilots tend to like some expos. In “Low Rates”, usually pilots prefer a low or zero amount of expo. In FS One, all of the “3D” airplanes use considerable expos. For the Edge 540, the expos in the “3D Rates” Flight Mode are 40% on rudder, 70% on elevator, and 55% on aileron. To some people, that will feel just right and to others it will feel like too much (especially to someone who uses 0% expo, 1-to-1 stick to surface movement). For some airplanes in FS One, even the “Low Rates” use expos. It’s all a function of pilot preference and it’s settable in the sim.
  • Step 4 (optional): Edit the FS One TacCon Controller (transmitter) settings to make it feel more like your own. From the fly window click on the transmitter and then make a copy of the transmitter. Click Edit to enter the Transmitter Editor. Click on the Flight Mode button at the top and select the particular Flight Mode to edit. Then, in the green section of the Transmitter Editor are all the values for dual rates and expos for that Flight Mode. Clicking on the items pulls up a box to enter the new values. As the edits are being made, the aircraft can be displayed at the same time by clicking on Show A/C. Click OK when finished. Your next Tx will be put in the first category at the bottom along with all the other FS One Controller setups.
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