Ramblings of a Wanna-Be Aviator

Discussion in 'The Projects Forum' started by monster_catfish, Mar 24, 2013.

  1. monster_catfish

    Thread Starter Active Member

    Mar 17, 2011
    For as long as I can remember, I have been fascinated by the magic of flight, though I hasten to add that this interest never did evolve into a flying career. Matter of fact, I have never flown real aircraft in my life, despite many, many hours of armchair “flight” with my trusty desktop flight-deck, built around the Microsoft 2004 flight simulator.

    To improve the realism quotient of my flight sim sessions, I acquired a cheap set of flight deck controls, namely a flight yoke and rudder pedals made by CH, and a throttle quadrant made by Go flight. I also acquired a decent collection of realistic ground scenery for airports and such, so that I can, for example see Heathrow Airport in all its real-world beauty, looming into view as the cloud cover breaks, while I coax my Level D767-300 jet down in short finals to the threshold of Runway 27R, for another perfect, crosswind-defying ILS landing at dusk.

    Over the years, I have dabbled in RC flight as well, and have learnt, after many a crash, to hover and figure-8 my long-suffering fixed-pitch Walkera 4-channel helicopter. With all this armchair “aviation” under my belt, it was inevitable, I suppose, that the growing craze in the RC world for FPV (First Person View) flying would intrigue me, and most likely result in another bout of impulsive buying of hardware accessories.

    Right now I am looking at buying the industry standard aerial platform used by RC fliers for FVP conversion – the Easy Star powered glider, along with the requisite video goggles, video transmitter/receiver combo, and CCTV video cam, to see if I can cobble together a basic, entry-level FPV system that I can hopefully use to learn the ropes, and hopefully have some crash-free exploration of the skies and landscape around here.

    Cutting to the chase, finally, I was wondering why nobody had so far considered marrying desktop flight simulator hardware with RC flying, such that the “pilot” of an FPV glider could guide his bird not with the standard hand-held RC transmitter, but rather with the same life-sized desktop controls long used for flight simulation, whereby the ACTUAL outside scenery over which the RC bird flies, is fed to a computer screen, or better still to an overhead projector that will produce a wall-sized image, such as I have for my MSFS flight sessions.

    The most widely used RC transmitters for flight surface and engine control are 2.4GHz units, while FPV gear generally utilizes frequencies in the 900MHz, 1.3GHz and 5.8MHz bands. My Spectrum DX5E transmitter that came with the Phoenix RC simulator, by way of example, is a 2.4GHz box, which can be used for real RC aircraft, as well as for the desktop Phoenix4 RC sim program.

    My question is as follows: How technically challenging would it be to interface the USB outputs from my desktop flight sim controls – the flight yoke, rudder pedals and throttle quadrant, with a transmitter connected to pair of outdoor antennae, one for the 2.4GHz flight controls, and the other for the 1.3GHz or 5.8GHz video link, both sitting atop a tall mast outside my house? My understanding of RF circuit design is as poor as my grasp of brain surgery, so I won’t be offended if the answers to my hypothetical question are simplified a bit.

    Obviously, my goal is to have a friend launch my powered glider from a nearby field, while I sit at my desk in the house, piloting the glider’s flight with my desk top flight sim controls, while viewing the real-life scenery as a projected full-wall image. So, I guess my question is, can this interface of desktop flight sim controls and RC-FPV flight be accomplished without the requirement for a PHD in RF electronics and really deep pockets? Any pointers that can be offered on this subject would be greatly appreciated. Much thanks in advance.
    Last edited: Mar 24, 2013
  2. monster_catfish

    Thread Starter Active Member

    Mar 17, 2011
    It just occurred to me that my question here might have been a bit too wordy, and buried far down in my introductory page, so I decided to condense my thoughts a bit more.

    I was hoping to learn if it could be feasible, and perhaps not too complex of an adaptation, for the USB-compatible flight controls that are used with desktop flight simulators to be interfaced with an RC transmitter running at 2.4GHz for flight controls of the model aircraft, and the second RC reciever operating at 5.8GHz, which displays video imagery from the aircraft's on-board CCTV video camera, such that the RC pilot can fly FPV (First Person View) using regular flight sim hardware( yoke, rudder pedals and throttle quadrant), as opposed to controlling the aircraft with a hand-held RC transmitter and FPV video goggles.

    Given that I have not actually attempted to actualize this idea, I am uncertain as to whether I should have posed this hypothetical question in the Off Topic section, or in the General Electronics forum, rather than here in the Projects discussion area.

    Any responses regarding how possible or otherwise this concept might be would be much appreciated, and if the mods feel this topic needs moving to a different area of the AAC forum, I would be grateful for their help in doing so.
  3. JohnInTX


    Jun 26, 2012
    Its a problem of multiple interfaces, programming. Doable but non-trivial.

    First off, you would have to know something about the USB dataset used by the flight controls. It might be available on the intertubes or perhaps you could use a PC based sniffer that would capture the USB stream as you wiggle the yoke, etc. Alternately, you could pick off the actual analog voltages from the controls, switches etc.

    All of that goes into a MAGIC BOX which decodes the control inputs and generates RC outputs.

    If your RC controller has a trainer input, check out its specs and drive the aircraft controls accordingly (analog volts from DACs etc).

    You've probably thought of all that but thought I'd throw something out. Check this out too. It would be a very cool project to do but..

    Here's a question for you. Since you want to be an aviator, why not spend your time in that direction? Would it be possible to present yourself at the local airport and offer to wash planes, help in the shop, fuel planes, answer phones or whatever in return for some dual? Many pilots, including myself, got their early hours in that way. I used to hang around the hangers after school. One day one of the A&Ps yelled over 'Hey kid! If you're just going to stand there, get over here and hold this danged thing'. Later I got my first ride on the test hop. Just askin'
  4. monster_catfish

    Thread Starter Active Member

    Mar 17, 2011
    I appreciate the reply, John, and from what you have mentioned regarding the hardware implementation of this idea, I am certain that this design concept is not something that I could embark upon with my very limited knowledge in RF electonics.

    I suppose the good news is that a stand-alone joystick flight controller is already available for RC-FPV applications, so I imagine it is only a matter of time before someone comes up with the facility to interface rudder pedals and a throttle quadrant for FPV-RC fliers who, like me, yearn for the full flight-deck experience, to captain their airborne model bird from the safety and comfort of home.

    As for real flying lessons, I may well look into that option at some point in the future when I feel I can afford the costs involved , but it would only be in the context of seeking a PPL for recreational weekend flying, since the inexorable the passage of time, and my increasing grey whisker count, have conspired to foreclose any chance of a career in real-life aviation for me, despite my life-long fascination with flying machines.

    All the same, I feel fortunate to be alive to witness the dramatic technical breakthroughs in RC and FPV capabilities already in progress, which already enable sky-gazing land-lubbers like me to further blur the line of distinction between real and simulated flight.

    Much thanks again, John, for your reply to my somewhat whimsical question here, and if the flight controls of my dreams ever do materialize for FPV-RC fliers, I'll be sure and mention that development here.
  5. monster_catfish

    Thread Starter Active Member

    Mar 17, 2011
    .Double post
  6. WBahn


    Mar 31, 2012
    Systems like you describe exist and are used by UAV systems all the time.

    For the amateur, one thing you have to contend with are the various laws (present and soon to be) which will probably require that your aircraft remain in sight of the person controlling it at all times. My understanding is that this is currently a big grey area here in the U.S. but that the rapid increase in the technology and availability of model aircraft has made it so that both the FAA and Congress are actively developing rules and laws, respectively, to regulate it.

    On the real flying side, if you were to total up the cost of everything you would have invested in a decent FPV system, you might well find you could have gone a long way toward a PPL or, as an alternative, a Sport Pilot License. Yet another alternative is to look into soaring.
  7. monster_catfish

    Thread Starter Active Member

    Mar 17, 2011
    WBahn the military UAV control centers whose pictures one sees on the net mostly are set up with joysticks rather than flight yokes, though there are no doubt sound engineering reasons for that choice of controls by the military.

    Given a choice of controls for a home-based FPV ground station, were such gear to become legally available off-the-shelf, I would prefer a yoke and rudder pedals over a joystick with a twist-grip rudder function, simply because the latter reminds me too much of a video game control. This armchair pilot demands realism ha ha.

    Regarding the cost of FPV equipment in general, I must admit I was taken aback when I got to tallying up the prices commanded by FPV hardware addons offering such features as On Screen Displays, gyroscopic flight stabilization, GPS, Return to Home, waypoint-capable autopilots and such, but, like all consumer electronics, vendor competition will ultimately force prices down and, maybe, bring some of those bells and whistles within reach of average Joes like me, assuming, of course that this whole field of endeavor is not legislated out of existence first.
    Last edited: Mar 26, 2013
  8. monster_catfish

    Thread Starter Active Member

    Mar 17, 2011
    I decided to go ahead and exhume this slightly dated thread because I learned recently over at the RC Groups forum that the interface needed to connect my desktop flight simulator controls to a regular radio control box does in fact exist, and is called the Compufly USB to PPM Converter, described in the folowing link.

    This compact connector will enable me to control the flight surfaces and airspeed of my RC aircraft from my indoor flight deck, however, even with the list of specific components needed to complete my proposed setup now known, the technical challenges of transmitting real-time 1.3GHz video signal from the airborne model to the ground station, and of transmitting the 72Mhz RC flight control signal from the ground station to the flying model, are daunting to say the least.

    The hardware configuration that I have in mind is to connect my components in the following sequence for the outgoing 72Mhz RC control signal.

    Desktop Flight Simulator Controls(Yoke, Rudder Pedals and Throttle Lever) will be connected to the USB input of the Compufly cable shown in the above link, with the Compufly output fed into a regular Futaba 9-Channel 72Mhz RC transmitter via a standard rectangular-plug interface cable sold with the transmitter. The 72MHZ RC control signal from the Futaba 9-Channel RC transmitter will in turn be fed into a 72MHz antenna power booster in the below link.

    Finally, the amplified output of the antenna power booster will be connected via 150 feet of low-loss 50 ohm coax cable, to a DIY copper J-Pole antenna sized for 72MHz, and suspended a few feet to the side of the transmission mast, about 120 feet above the ground.

    The 1.3GHz video reciever that I hope to use is in the below link, from Ready Made RC.

    Since my intention is to position my 1.3Ghz video antenna 120 feet up a tower, my first question is whether it is indeed possible to separate the video reciever from its stock whip antenna with the 120 feet of 75-ohm low-loss coax needed to place that antenna close to the top of the tower, while the video reciever itself is located in my flight deck shed at the base of the tower.

    The 1.3GHz video signal recieved from the flying RC model, by the tower-top whip antenna, will be boosted by a video line amplifier, which I hope will send a relatively clean signal down 150 feet of 75 ohm low loss coax, to the reciever at ground level.

    Below is a link to the spec sheet on the video line amplifier I have tentatively chosen for placement near the top of the tower in a weather-proof container, where it will be connected to the 1.3GHz video reciever whip antenna, and powered by a 12-VDC line that will be fed up the tower.

    My second question is with respect to the signal propagation delays, if any, that one could expect to see with both the outgoing 72MHz RC control signal, and with the incoming 1.3GHz video signal.

    Assuming for the time being that the 150 foot long coax connections I have described above would indeed work as expected, is it likely that there might be a time- lag in either the outgoing RC control signal, or in the incoming video signal, that could make flying the RC model impossible ?

    Any pointers that can be offered before I make any equipment purchases, would be much appreciated. I apologize for the wordy description of this project, but I am trying to convey details of a rather complex series of hardware connections, without the benefit of a diagram.
  9. Shagas

    Active Member

    May 13, 2013
    Are you planning to use the DX5 for this project?
    I'd suggest using a much higher-end model due to range , reliability and extra features
  10. monster_catfish

    Thread Starter Active Member

    Mar 17, 2011
    Thanks for the reply, Shagas.

    Since I will be using 72Mhz for my RC control signal, I wound up selecting a Futaba 9-Channel raido, shown in the below link. This is apparently an updated version of the more archaic 72Mhz RC radios that can be picked up far cheaper on ebay. Unable to find a used and more affordable 72MHZ Futaba 9-Channel radio, I bit the bullet and placed an order for a new one.

    The Spektrum DX5 is a 2.4GHz unit, to the best of my knowledge, but I chose 72MHz over 2.4GHz because the RC control signal reportedly carries further with 72MHz than with 2.4GHz, which is more susceptible to interference in areas with lots of trees, as is the case at the location this ground station flight deck is being set up.

    My Phoenix RC simulator was shipped with a Spektrum DX5 (5-Channel) transmitter, so I am familiar with that make and model, though admittedly I do only use it plugged into my computer to fly in the virtual world of Phoenix4 RC.

    For my ground station, the Futaba was also a convenient choice because it is shipped with the rectangular-plug interface cable that is needed to connect the RC radio with the CompuFy cable that will allow me to use regular desktop flight simulator controls to fly the RC plane.

    I am hoping to attain more range out of the system by amplifying both the outgoing 72MHZ control signal, and the incoming real-time video signal, as detailed in my earlier post above. Done this way, the stock antenna on the Futaba radio is replaced by a home-made copper J-Pole antenna, sized for 72MHZ, and located at the end of 150 feet of 50-ohm coax, atop the 120-foot tall tower, where it will have clear line-of-sight above the tree-tops.