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Recent content by JohnFortier

  1. JohnFortier

    attenuation-distance-frequency

    Martin, As I recall, the formula is 34.4dB + 20 log10 D + 20 log10 F. = Loss D is in Kilometers and F is in Megahertz This will give you a propagation loss figure in dB. To this you should add your transmit power in Dbm, your antenna gains and any co-ax or waveguide losses. Together these...
  2. JohnFortier

    Replace Winglets with Vertical Tail for Canard

    Have you considered that the removal of the winglets might produce tip vortices which might in turn induce flutter at a fairly low airspeed? I'd check into why the winglets were used in the first place before making this mod. Cheers John
  3. JohnFortier

    Aeriks Aceair + Williams Turbofan

    I'm not actually silly enough to deliberately exceed VNE. My interest was in how much true airspeed could be gained by cruising at a higher altitude, which would be possible with the Williams. Considering the thrust to weight ratio which would be achieved with the Williams, even at 1000 lb...
  4. JohnFortier

    Aeriks Aceair + Williams Turbofan

    I'm thinking of combining the Aceair with a small - 1000lb thrust - Williams turbofan. Simple question I know, but since the Aceair normally uses a 110 HP rotary wankel engine, is there an easy correlation between HP and lbs thrust. Another question on the same general subject; the Aceair...
  5. JohnFortier

    Energy efficient air amplifiers

    I'll probablty get shot doen in flames for suggesting this, but I remember using a Jetex "engine" in model aircraft with what was called an augmentation tube. The Jetex was really a simple slow burning rocket engine, with a small hole at the rear instead of a venturi, {had to be affordable to...
  6. JohnFortier

    Three-Lifting Surface

    Actually, Ritchie, while I hadn't considered a thousand seater to be the next logical design step for TLS, I had thought about a possible replacement for the C130 Hercules. I leave the rest up to your imagination, but it seems something of a natural development. Regards John
  7. JohnFortier

    DSL speed for dial-up

    Johnwiss, There is no practical limit to the numbert of users who can be served by the DSLAM. The major restriction on DSL is crosstalk, which increases with both frequency and number of DSL transmissions in a connecting cable bundle. One would think that the range would also affect the level...
  8. JohnFortier

    Telecommunication Network Design

    When you say Telco networks, are you referring to the access netowrk? The access network being the installed cable, wiring and cross connect infrastructure. If so, I should be able to help you considerably. John
  9. JohnFortier

    external Cat5/ ethernet Cabling

    Glen, Here's a thought: As an alternative to burying and shielding a cable, why not place a passive repeater on your factory roof. Two shrouded yagis, which at LOS frequencies are very small, connected back to back, with each one pointing at the, very small, dish of your tranceiver on its...
  10. JohnFortier

    external Cat5/ ethernet Cabling

    Glen, This doesn't answer your question, for which I apologise, but why, at 150 feet, is LOS a null? At that distance you should not only be able to send just about anything over LOS, but you would need to install atttenuators in your antenna leads! Unless there is a huge, earthed, metal...
  11. JohnFortier

    Wireless (Wi-Fi) Communications

    It's been quite a few years since I was involved in telecomms on oil platforms. That was inthe North Sea, usually under BASEEFA/CENELEC regualtions as far as intrinsic safety was concerned. I'm fully aware of the time and trouble it takes on a platform to retrofit any communications system, so...
  12. JohnFortier

    Analog Linearization

    I'm afraid I'm a bit in the dark here. Linearization of what signal under what circumstances? John
  13. JohnFortier

    Coax Termination into 2-Wires

    Presumably the co-ax is carrying the 4-20 mA loop with the outer braid acting as the return path. As long as this is earthed at each end the, basically DC, signal on the line won't be bothered by RF interference. 4-20 mA transmitters and receivers have filters to remove such interference...
  14. JohnFortier

    Covert internal 3.5 floppy for use as an external drive

    Quite honestly, this sounds like an exercise in frustration. The expense of hooking up your floppies externally will probably get close to the cost of an external floppy drive, with no guarantee that your lash up is going to work. Have you considered using those spare floppy drives by doubling...
  15. JohnFortier

    Aircraft propeller configuration

    You're quite right wilg, it's the XB35 that had the contra-rotating pusher props. A large, flying wing design and a competitor for the strategicv bomber contract eventually won by the B36. Problems arose with the gear boxes, which were apparantly government issue (why did the government have a...
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