GPS Telemetry – First Flight

I picked up the Spektrum GPS module over the Christmas holiday.  Somehow I was not even aware when this item came on the market but when I saw the ad for it I knew I had to try it.  I immediately dropped an email to my friendly local hobby shop and a few days later I picked it up.  I already have telemetry in my Wildhare 50cc size Slick as well as my Topflite P51 “Redtail” Mustang but this, in my mind, was a totally different level.  I’ve already posted on some basic telemetry usage in my Radian glider, but being able to track altitude, heading and speed in addition to GPS coordinates was potentially a game changer.  In my mind, there were so many possible upsides to this new sensor.

The module is a bit pricey, but you have to keep in mind that the GPS module is a possible replacement for a couple of the other existing Spektrum sensors and therefore some of the sting of the ~$100 price tag is diminished.  When you throw in the heading and position facilities the module starts to seem a bit more reasonable.  Lets be honest, none of us fly RC airplanes because its a particularly cheap hobby do we?

That was my train of thought when I got busy and installed a TM1000 and the GPS module in my trusty Telemaster 40.  Looking at the local weather forecast on the shop TV convinced me to add the floats as well.  Skis work in some snow conditions but I have found floats work well on a wide variety of ice/snow or water.  A quick test start on the trusty Saito 82 and a good overnight charge and all was ready.  A couple days and 4-6 or maybe it was 6-8 inches of white stuff later and January 1st, 2013 dawned calm and cool.  Time to test out the new GPS module!

After a nice long flight, I entered our club’s nicely heated shelter, downloaded the telemetry file and emailed it to my old (original model) Ipad.  As you can see by this clip (I’ll insert a video here eventually) the STI application can overlay the collected flight track on what appears to be a satellite shot of the flying field.  Then you can replay and watch as the entire previous flight plays out as a small airplane icon moves across the map and leaves behind a trail of arrows.  A window can be brought up showing all the GPS information as the flight plays out on the map.  By noting the heading, altitude, speed, etc… and comparing to the track you quickly start to recognize loops and stall turns and can easily see just how close you came to that tree line or how high you really flew.  This is extremely cool stuff with some real life usefulness behind it.  Here is a small sample video showing the first minute or so of my flight.

You can see a fair bit of information in this.  First its around 808ft above sea level at our field.  You’ll see it on the screen until about 24 seconds in when I take off.  You’ll also notice the time in UTC format.  Locally it’s a minute or so after 9AM which is when we were allowed to start flying the “noisy” planes at this event.  My speed ranges up to about 65mph (that is full throttle and a pretty steep dive) and my max altitude above the 808 foot base seems to be about 250 feet toward the end of the clip.  At about 1:23 you will see the speed drop to near zero and a very quick heading change as I perform a stall turn… at least the best I could with floats on a Telemaster!  It takes a bit to figure things like that out.  You just have to imagine what is happening that would cause the changes in altitude, airspeed and heading to reason it through in most cases.
Of course there is plenty of room for improvement.  Here’s my top three:
  • Allow me to pause the flight and clear all those little arrow tracks.  After a while I can’t see the airplane icon for all the little arrows.
  • Give me the ability to “zero” the altitude with the push of a button and let the program do the math to tell me what the variance in altitude is from that point on.
  • Put a scale of some sort on the screen so I can get some sort of idea of relative distance… even better if I could set a zero point just as I’d like to do with altitude and let me see distance from that point.

Having said that, this technology makes a lot of valuable information available to us.  During part of my flight I flew out “close” to our northern tree line… or so I thought.  On review I had more available space than I thought.  Very good to know.  When practicing for IMAC, one of the prominent issues to watch for is flying a straight line parallel to the runway with a constant altitude.  Without the ability to do this you will never score well at a contest.  This is a lot more difficult than you might believe.  With GPS telemetry, you can answer these question once and for all.  As you might guess, the GPS module has already been moved (likely permanently) into my Slick (my IMAC dabbling plane) and another has been ordered.

How fast?  How far?  How high? Where?  When?  All those questions are answered once and for all with GPS.  I can’t wait to get a plane in the air with a GPS combined with a “full boat” of other sensors.  Ever wonder how your engine temperature varies with throttle and speed?  What the unloaded RPMs really are in flight?  I’m looking forward to learning all those things during this upcoming flying season.

I’ll try to write up an article some time soon showing all the Spektrum Telemetry pieces and parts and the ins and outs of making the system work.  There are some small quirks but nothing overly difficult and the information gained is fascinating.

Spektrum Telemetry – Altitude and Flight Voltage in a Glider

I have recently been exploring the Spektrum telemetry system a bit.  I have fairly full house Telemetry install in my 50cc size Mustang but it has limited flight time at this point and getting it out in the snow wasn’t feasible so I started with a smaller testbed to do a little experimentation.

I installed a TM1000 Telemetry receiver into my Parkzone Radian glider.  I had recently replaced the original receiver in that bird with one of the new, low cost 4 channel DSMx receivers which just so happens to be telemetry compatible so by just running the standard wiring from the data/bind port on the receiver to the TM1000 I had a working system.  I then added the Altimeter sensor and created a little wiring harness to tap into the balance plug on the 11.1V, 1300mah LiPo flight pack and I had access to a fair amount of information.  I could see fades, frame loss and hold on each antenna as well as receiver voltage and the pack voltage plus the altitude.  I went out to my test area (known as the side yard) and made a short glider flight.  Here is what the display on my iPad looked like when I downloaded the data afterwords.  The red line is the battery voltage (note the drop in voltage when I was climbing/running the motor).  Green is altitude.

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While examining the data after the fact on the iPad was interesting and informative the best part was what the system allowed me to accomplish while I was flying.  During the flight I had the display up on my DX8 showing altitude and while having the motor shut down was able to get into some lift that I believe was coming off a neighbors roof heated by the sun.  I noticed a bobble that I thought might indicate some lift but couldn’t tell whether I was getting into a lift area or not… the bird was already at 500+ feet altitude and a couple hundred yards away at the time and I just couldn’t tell visually whether I was gaining altitude or not.  By peeking at the display from time to time and circling around the suspect area I was able to figure out when and where I was gaining altitude and was able to verify where to position the Radian to gain some altitude.  I spent about a minute continually peeking at the altimeter readout and circling back to the lift area and gained about 150′.  While I’m sure others could do much better and probably do so without any need for instrumentation, for me this was ground breaking stuff.  It was the first truly useful example of what these tools can add to the game that I’ve seen and it convinced me that adding telemetry could give me more than just some cool factor!  I’m already thinking about other ways to make use of some of the other available Spektrum Telemetry sensors.

Next time I’ll talk about my first experiment with the GPS sensor at our New Years day “freeze fly”.

Parkzone UMS Sbach 342 3D

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My Sbach – A fast but stable aerobat thanks to AS3X

I’ve had the little E-flight AS3X equipped Sbach for a couple months now and the first thing I’ll say is it isn’t what I’d consider a great indoor plane. It seems to fly better fast and I personally don’t enjoy spending all my time just “missing the walls”! However the stabilization system really makes it fly more like a larger model… Maybe akin to what you’d expect from a 40-60 power model. It’s quite impressive. Though I’m not much of a 3D enthusiast I have been trying out hovering a bit with it and it seems to be doable as power is not a problem.

As an outdoor airplane it flys very well with sustained knife edge, (use the side force generators from the beginning) crisp feeling 4 point rolls, loops small or large, stall turns, snaps and more within its repertoire. Landing takes a bit of work as it needs to carry a bit of speed for anything resembling a normal landing. The best thing is it can do all that in 10 to perhaps 15 mph winds if you remember to correct your flight line with judicious use of rudder! That’s impressive for a sub 3 ounce aircraft.

All in all, I enjoy the little Sbach. While the AS3X system does make for some seeming “resistance” to smaller control inputs, it also makes the plane track great even in high winds that other micros can’t handle. Flights don’t seem to be to short so the little 180 mah battery seems to be about right. It’s unfortunate it has a different connector than anything else I’ve owned before, there is a little adapter cable from horizon that adapts it to most balancing chargers so if you don’t get the model with the charger or want another option there is a fix out there.