How much interest would there be in an Ultrasonic Altimeter for ultralights?

Discussion in 'Instruments / Avionics / Electrical System' started by jrsteensen, Oct 11, 2014.

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  1. Oct 11, 2014 #1

    jrsteensen

    jrsteensen

    jrsteensen

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    How much interest would there be in an ultrasonic altimeter for ultralights? I found a sensor with a 10 meter/30 foot range, self calibrating for temp/humidity. Should be useful at 60mph forward speed according to the vendor, down to zero. Environmentally sealed.

    I'm building/programming a prototype now.

    Features:
    • Visual readout in feet or meters (daylight readable 2x16 OLED)
    • Audio output to a 3.5mm stereo jack - plays a series of tones every (TBD) feet/inches, goes to a solid tone at 6 inches. Able to enable/disable the R/L channels independently.
    • Offset - to allow you to account for the vertical distance from the mounting location down to the landing gear. Adjusting this offset does reduce the range by the same amount.
    • Runs on 12V down to 3V input.
    • Sensor is at 10hz, which means plenty fast.

    I'm going to do some ground testing (i.e. stick it on the top of a piece of pipe, move at a good clip down a dirt road, and have a passenger raise and lower it) then (since I don't have my ultralight done yet) find someone to flight test it for me.

    This unit will be a dash top - I will be able to build it into a instrument form factor if there is desire in the future. Package shouldn't be more than 3.35x1.75x3in total. Sensor will be mounted remotely.
     
  2. Oct 11, 2014 #2

    BBerson

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    Might be usefull for glassy water landings on floats.
    For land, I can't see much need.
     
  3. Oct 11, 2014 #3

    jrsteensen

    jrsteensen

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    You are absolutely right, there isn't a particular need. It's a fun project and a cool little gadget. It will work over water as well as land. Most I've done so far with the sensor is hold it out the window of the car, and it seems to be quite accurate. (1cm resolution)
     
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  4. Oct 11, 2014 #4

    cluttonfred

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    It might also be useful for racers or other types with poor visibility for landing.
     
  5. Oct 11, 2014 #5

    FritzW

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    I think it would be a fun project and it probably has a need somewhere in aviation. But there's a fine line between "useful technology" and replacing basic pilot skills with a "gizmo". I can see a situation where a guy "prangs one on" because the tone in his headset overruled his situational awareness.

    If you know how to land an airplane (sight picture, sound of the air, feeling in your arse, etc...) your device won't really help and might just add another element you to have to think about. If you start depending a "gizmo" to tell you what you should already know, you'll be screwed the first time the gizmo gives you bad information.

    For me there wouldn't be much interest in an "Ultrasonic Altimeter for ultralights". (except to play with)

    P.S. I spent months playing with a AoA indicator built from plans in an old Sport Aviation issue, but data from my eyes, ears and ass always came first.
     
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  6. Feb 22, 2015 #6

    Rob_O

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    My interest level would be dependent on your price level. No need for a display, just a box with a cord to plug into your headset giving you a tone that changes pitch as you get closer to the ground.
     
  7. Feb 22, 2015 #7

    cluttonfred

    cluttonfred

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    Fritz, how about some pics and a "review" of that old AoA indicator, here or in another thread?
     
  8. Feb 22, 2015 #8

    BJC

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    IIRC, the Gossamer Albatross used an altimeter made from the auto focus mechanism from a camera.

    A range of 200 feet might draw some interest, not from ultralights, but from E-AB's.


    BJC
     
  9. Feb 22, 2015 #9

    SVSUSteve

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    In that case, the smart pilot would be going with a certified radar altimeter or- more proactively- going to an airport with better weather conditions. There's using the technology available to you and then there's just pressing your luck. My guess would be that a simplified system that reads out two hundred feet and calls out "MINIMUMS!" would be a better option for a single pilot IFR cockpit unless you're fitting it out for a CAT II/coupled approach. LOL

    Someone mentioned glassy water landings...that's one of those things that has always made me wonder why more amphibians or floatplanes aren't equipped with something like a radar altimeter (yeah, cost....I know). I've been on a floatplane landing under those conditions during a fishing trip up in Canada...it's amazing how little depth perception one has in that setting. The fact that the pilot did it successfully (and in one of the smoothest landings I have ever experienced) made me develop a HUGE amount of respect for him and other seaplane pilots.

    Given how easy it is to program something to give voice call outs (if I can do basic programming, anyone can), it would make more sense for one to use callouts of "200, 100, 50, 40..." and so on than a tone that might be cancelled out or altered by cockpit noise, electrical interference (some airlines used to use a radio approach back in the 1940s and 1950s that relied on tones and there was at least one crash I am aware of due to the effects of static, etc) or out of the range of hearing for certain pilots.
     
  10. Feb 22, 2015 #10

    TFF

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    All airliners today have radar altimeters, and I believe by 2017 all PT 135 helicopters must have one, unless they extended the date. They do the call out of ft. Pretty much all landings for airliners are done with gauges. Once within a 1/4 mile of the threshold, the only part of the runway they can see through the windshield is the other end of the runway. Thats a clear day.
     
  11. Feb 22, 2015 #11

    SVSUSteve

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    I haven't heard of any across the board extensions but then again I generally only pay vague attention and then only to the HEMS stuff (most of my helo crew friends are in HEMS).
     
  12. Feb 22, 2015 #12

    Dana

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    I agree with most of the above, it's a solution in search of a problem, except possibly for the seaplane application.

    One of the previous owners of my Kolb was having trouble learning to judge his flare, so he adapted an ultrasonic distance finder that was sold as a garage parking aid (went from green to yellow to red the closer you got). The Ultrastar has to be flared quite accurately as there is no shock absorbtion beyond the tires; flare even a little too high and you break something. It really didn't help him... his real issue was that he was trying to learning to fly at over 80 years of age, when it's tough to pick up new skills. Fancy gadgets are no substitute for good flying skills.

    Dana
     
  13. Feb 22, 2015 #13

    Wanttaja

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    Snort. Fly Babies don't have shock absorption beyond the tires, either, and we've never needed radar to fumble our way down.

    Mind you, the Fly Baby's gear *is* a bit strong. I've had at least one landing that pegged a G-meter (4 Gs) with no damage. And check out this picture of a crashed Fly Baby:
    horsten1.JPG
    Note the landing gear propped up on the wall in the background...It tore the fuselage apart, before it (partially) failed.

    To me, the biggest problems with this kind of device are: How do you tell the pilot, and what is he expected to do with the information?

    Dana's acquaintance was on the right track...not trying to make sense out of blurred numbers, but a simple three-color scheme for use at the flare. But still, I'm skittish about looking at a dashboard indicator when approaching the flare. I don't even look at the airspeed once I cross the threshold; totally focused on the sight picture outside.

    A better solution would be an audio indicator... slow pulse, low frequency when high, with the pulse interval decreasing and the frequency increasing as one gets closer to the ground.

    Consider, too, what the device is doing if you're NOT landing. Unless you put some kill switches in there, it'll be squawking at you when you take off, or even when you're just sitting stationary. You'll want to add an inhibit switches to the throttle (don't operate if the throttle is more than ~1/2 way pushed in) and pressure switches to sense when you're on the ground (these switches can be fiddily when you don't have a shock-absorbing gear).

    A better use for these devices, and one that potentially is pretty lucrative, is a landing-gear warning system for retractable-gear aircraft. Right now, the systems only tell you when a combinations of circumstances might mean that you could be landing with the gear up....such as stall practice at altitude. With a system that ONLY alarms when you're below 30 feet with the gear retracted, the pilot would be more likely to notice the horn.

    Years ago, we received a "Polapulse" range system at work for experimentation (odds are it's what Dana's friend had). I always thought it would work nice as a gear-up-landing warning system. Put the emitter on the gear door, so when the gear was down, it was pointed off to the side and wouldn't detect the ground....

    Ron Wanttaja
     
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  14. Feb 22, 2015 #14

    recmob

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    Dana,

    Were currently in Beta Test with a similar type unit that has been in development for 4 yrs now. Its not easy and has been a long road, and the components (especially the transducer) is extremely expensive. Its very, very close to release. Just tweaking the software a little more.

    FlareAssist Ultrasonic Altimeter

    I don't mean this post as an advertisement, if you can develop a unit with similar features and lower cost, more power to you!
     
  15. Feb 23, 2015 #15

    Rob_O

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    Can you count from 30 to zero faster than an ultralight on approach can fall out of the sky? Can you keep up with that count while you are trying to land that ultralight? I'm thinking it could get real confusing real quick while a tone would be much easier to follow

    Yes, exactly what I was thinking. I like your idea of the inhibit switches, but if you set the minimum range about 6" before the gear touches you know where you are when the box stops beeping.
     
    Last edited: Feb 24, 2015
  16. Feb 24, 2015 #16

    cluttonfred

    cluttonfred

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    This audio indicator like a hang glider variometer is a great idea, perhaps combined with a synchronized light on the dash as well? You'll need a timed mute button as well.
     
  17. Feb 24, 2015 #17

    Dana

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    $2450.00, yikes! That's almost what I paid for my entire airplane. At that price I think it's truly a solution in search of a problem, especially if you're marketing it to ultralights and homebuilts.

    Not me, I have no use for such a thing.

    Dana
     
  18. Feb 24, 2015 #18

    Wanttaja

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    Excellent idea. That way, you eliminate the mechanical squat switches and handle it all in software.

    Ron Wanttaja
     
  19. Feb 24, 2015 #19

    Joe Fisher

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    I kind of wonder where the pilots are. Its called peripheral vision.
     
  20. Feb 24, 2015 #20

    Wanttaja

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    I'm kind of reminded of the pilot who timed his flare by the sudden intake of breath by his passenger.... :)

    Ron Wanttaja
     
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