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Old Feb 20, 2012, 08:35 AM
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Regardless of the "Meat servo" thing, the pilot will always have the option of using the information provided by the telemetry or not. IMHO if a pilot depends only on that info at all times, then he's bound for a relaunch in the near future. Electronics can often cause more problems than they solve. Hence the old saying... TO err is human... but it takes a computer to really screw things up!
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Old Feb 20, 2012, 09:26 AM
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Originally Posted by ThermalSeeker View Post
It appears that GPS data to be used to determine if you've made it to the turnpoint is favored by most.
Keep in mind though that if I use GPS data to make my turnpoint, I then make my turn, establish a new heading, take a GPS reading, then 20 seconds later take another GPS reading, I now have my exact ground track given to me or I can be told how far I need to adjust to be on track to the next turnpoint. I don't need to estimate drift from winds aloft or coordinate with my team as to where I want to be next. My GPS info has done that for me. (assuming that I can hold a heading)

Is having course and ground track information going to be an acceptable byproduct of being able to be told that you've made it to the turnpoint ?

Mike
Since I have not yet done r/c xc and am learning from this site, please correct me if I have this wrong:

1) currently in XC competition, GPS is used to verify the contestant's track and having reached each turnpoint and can confirm time to complete the course.

2) The course is laid out utilizing roads which the chase vehicle uses.

Using these principles, I do not see the conflict. Using your example: ok the pilot knows his aircrafts heading for that moment, but he still has to hand fly the model in a fluid medium (air) which is always in motion. The pilot and chase crew already know the course heading to next turnpoint (prior to reaching the turnpoint) because they will be driving the road. The GPS data only confirms visual input. The pilot and crew still have to make the judgement calls: how far ahead of the car do they fly, how high, how far off to the side, etc.. The theoretical advantage of having GPS streaming data to the pilot will enable the team to make the turn at the turnpoint as tight as possible to enable proceeding on course as soon as possible, resulting in a more efficent (and faster) race track. In one way, consider the GPS serving the same function as a flagman in a slope or pylon race or in F3B.

In full size soaring xc; yes we have GPS, yes the GPS can show heading to turnpoint, yet the pilot still has to make the judgment call on where to fly to get the lift and avoid the sink. When I finally officially flew my FAI 50 kilometer (34ish miles) last summer (with a flight data recorder which worked and recorded the entire flight!), the actual ground track ended up being a horribly convoluted zig-zag course because I needed to avoid areas known for nothing but sink, plus there were large areas of relatively stationary cloud shadow. The GPS helped me with situational awareness in that I knew where I was and where I needed to end up at. How I got there was my judgment and my decision. At the end of the flight (which actually was a 50 km goal and return) three hours later, I was a very happy camper!

Scott
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Old Feb 20, 2012, 10:59 AM
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Cees
Please post whatever you think might add to this discussion.

Scott, to reply to your questions:
1) currently in XC competition, GPS is used to verify the contestant's track and having reached each turnpoint and can confirm time to complete the course. YES, FOR MOST CONTESTS WE NOW REQUIRE AN ON-BOARD GPS LOGGER AND THEN DOWNLOAD THE RECORDED FLIGHT LOGS AND USE THE FULLSIZE SOARING SOFTWARE "WINSCORE" TO SCORE THE CONTEST. GPS LOGGERS ARE NOW AS CHEAP AS $25.

2) The course is laid out utilizing roads which the chase vehicle uses. YES

Joe, I think there can be some competitive advantage to be gained by using a computer running soaring flight software to provide guidance to the pilot, but I don't think it would be decisive. Soaring computers are used effectively in fullsize soaring but I think given that in RC we a limited in altitude and in location (must fly near roads) the advantage gained is limited. I have tried using gps telemetry and it proved to be more of a distraction than a help so I ended up not using it. On the other hand I believe Bob Nelson used gps telemetry and a soaring computer effectively in the past. I'm sure Bob can shed more light on this issue.
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Old Feb 20, 2012, 12:34 PM
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My Sky Melody/Sky Panel setup is three units, the Melody, the Panel and the transmitter. The Sky Assistant is the same thing but its all in one unit and its quite a bit cheaper, about $300. I can see in the future where we will have something like the Sky Assistant but also with GPS and airspeed info downlinked to the team's PDA or Ipad, etc., all for a very reasonable price and all of it included in one small unit.

The only thing I see as absolutelly necessary for competitive XC is a good compensated vario which we all already have. Airspeed would be nice but not critical as we pretty much know the speeds we are flying based on trim and flight mode. GPS downlinked to the team could be an advantage, especially at turnpoints as you would no longer need to be directly under the glider at TP's. Also GPS info would be great when flying way off to the side. At Cal Valley and Montague there are many times when I want to fly down a ridge or line of hills but I have no idea if I am over them, past them or not far enough out, I'm basically just guessing. GPS data could really help in centering over terrain or known thermal generators. Also on the final sled run. Sometimes we are going scary fast to keep up with the sailplane near the finish. With GPS it would be possible in those situations when we dont properly guage remaining altitude and distance and need to burn excess altitude with speed to not have to drive so fast and let the saiplane overtake and head out ahead and still know when it actually crosses the finish line. This might take some of the excitement out of the final dash but would be safer.

Steve
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Old Feb 20, 2012, 02:01 PM
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John, gents,

Not even seen a XC contest in your country but even my contribution.

XC has to do with distance, flying a circuit with use of thermals and cruise the optimum way from one thermal to the next (if it's there!).

Basicly we humans aren't designed to fly and especially not with restricted feedback, optical. Flying the real we have a lot more information!!!

Modeling

Being depending of thermals and cross the country we basicly miss information for two different phases of the flight.

First phase:
Finding and flying in the thermal by finding the centre and I think often on fixed location (I can be wrong!). Gaining of height is "filling the tank"
In the Netherlands near the coast we often have streets of clouds and thermals, did fly the glider from each street to another without any problem for a fixed location of the pilot.
Cross country also will have to do with travelling thermals too but they will often have another destination than you have.

So what about travelling, our own travelling?

Second phase:
In my opinion you need an instrument showing you the important information of what is outside the thermal too, for the optimum way of consuming the heigth we did reach in the thermal!
Maybe you do, by calculating that optimum way, but I don't read anything of that and if you already do I wonder how!!.

IMPORTANT
What is the optimum way of consuming the height?
Just as the instrument did tell you were the thermal was and the centre, now the instrument has to tell you the optimum way to consume so the optimum speed.

"Optimum speed?" GPS speed?" "NO of course not, airspeed."

For each track there is an optimum airspeed to fly when not in a thermal but when cruising to the other thermal. Calculation of that speed has to do with polar of the glider, direction and value wind and RISING OF FALLING OF THE ENVIRONMENTAL AIR.

I show a diagram of an instrument of one of my gliders, the Sagitta, 2,5 m span, that can help us,

1 It's a TE variometer for finding and centering the thermal.
2 It;s a Netto TE variometer to know in what kind of air I am flying
3 It;s a Relative Netto variometer, so when I am cruising from one thermal to the other I detect the environmental air if "there is a little fish?"

What we see?
The principle of a variometer of about 40 years ago. still used by me but forgotten by many other pilots and manufacturers.

Ideal example to show how an instrument can look like inside!

How it works

In thermals
Airflow out- and into the capacitor by measurement is info for in thermal "UP" or outside thermal "sinking".

Gaining of speed,
The dynamic pressure rises and the TE compensator will press some air volume in the capacitor result is a TE positive detection of energy.

Stick input for elevator,
Both! Adjusted are dynamic pressure changes and static presure changes the way so output of information is zero. TE compensation 100 % adjustable!

Now we are going to travel. start your engine.

Switch on the “Netto option”, with use the solenoid valve,The dynamic pressure of the pitot tube will generate a positieve airflow to the capacitor, result is some air will flow out of the capacitor throught the flow measure element to static holes of the tube,

This results in a positive variometer signal.

What about when the positive signal is of same value as the sink of the plane at that speed? Would be interesting or not?

When we increase the speed, dynamic pressure will be of higher value so the positive signal of the instrument too! Indeed but sinking of the glider also will be more and output of the instrumet still can be zero.

Whatever speed we fly (within limitations) the output of the instrument is zero, when the environmental air doesn't rise or falls. The facination of calibration!!

Because our instrument can measure the sinking or rising of environmental air around the plane, our navigator can calculate the optimum of speed related to track and wind. When we have to do with falling air our result of calulation will be a higher speed!

Now we are in trouble!!
Weak thermals and a long way to go!
Switch on the “Relative”, and a small added calculation is done in the instrument, telling us what is possible when we explore a weak thermal we pass, is there some gain for us or not? No! Continue the track.

Gents,

Not much in the glider and in this period I fly with fixed netto because of "lack of space" in the shuttle for the "solenoid", but the vario is real and can be expanded with Mc Cready facility.

In that case we adjust a value of climbing we did measure in the thermal (McCready) and the inlfuence of wind on our track, calculated by our team, in the instrument and the instrument does advice us (by acoustic information of pulses, if we have to fly slower or faster to have that optimum of speed in the air.
The instrument uses the information of measured vertical and horizontal speed of the plane to do that, We only have to control the elevator while we not even know the speed!!!!!.


Interesting story?

Let me know and if you understand the story, look which functions I needed in my observaton as pilot to fly thermal and cruising between the thermals.
I only did hear the crew telling me to fly faster or slower because they did use the polar of the plane, the direction of wind and my information of the vario about the air (rising or falling) to calculate the "ground speed"

With the McCready the pilot is the bos, only hearing the windvalue of the team to adjust the variometer.

It's along story in a foreign language so I think it all will not be clear, also there will be other questions, so let me know.

Other point of course is, what this has to do with the poll? But alo that can have some more attention. Only keep in mind that I nearly don't need anything to write this story or do my job as the pilot only a Mc Cready variometer and a driver.


Cees
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Old Feb 21, 2012, 11:13 AM
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Quote:
Originally Posted by John Ellias View Post
On the other hand I believe Bob Nelson used gps telemetry and a soaring computer effectively in the past. I'm sure Bob can shed more light on this issue.
Hi John/all, yes I’ve been lurking… I guess it is time to chime in.

About ten years ago our team tried using a flight computer.
It consisted of a GPS, two 900MHz transceivers, and a Palm PDA running SoarPilot S/W. Find the S/W here: http://soaringpilot.org/

I said tried because it wasn’t very successful; the radio connection kept dropping out. We abandoned the project for two reasons, the radio connection and a reduction in team membership.

In those days it seemed easier to find people who wanted to be on a team and fly XC and so we always had four members. Now two or three on a team are the norm.

Using a flight computer for models gives you all the information a full scale XC sailplane pilot would use or need. There just needs to be someone there viewing the screens for information. Current, commercial, yet free, flight computers all require someone to be viewing the screens.

I don’t see the use of a flight computer for model XC while teams remain at the two to three persons. There are some discussions going on in the threads here that talk of making it an all audio system.

If someone wanted to try this now, I’d probably go with the equipment that Rick presented in this thread: http://www.rcgroups.com/forums/showt...&highlight=gps

At Montague last year, I ran a tech session on the next generation telemetry system. From that there was four items, pieces of data, which the pilots/teams wanted:
• Vario
• Altitude
• Airspeed
• Buzzer alert when inside the 0.2 mile radius cylinder of a turnpoint

All information was to be provided by audio.

I went off and took a look at the feasibility of making such a product. The major roadblock that I saw was getting FCC approval to make a product that transmits and being able to pass those costs onto the consumer. FCC licensing would cost anywhere from $5K to $10K. At Montague, we had 14 teams, say ten of those would want one of these. At the $10K price that would be $1K just for the licensing, plus all the costs for the product design. If I sold 50, then the cost would be $200 plus design. No one is going to want one of those. Sorry if this is too analytical…

The way around this is going open source… There are many fine designs of hardware and software that one can use to make this work. Just take a look at the other current threads in this section. Some electronic building and software knowledge is required.

Take a look at Zenoid’s blog. He has done some wonderful things with an Android phone, even has audio for all those that want it. Perhaps Zenoid will be willing to share. Find his blog here:
http://www.rcgroups.com/forums/member.php?u=65963

- Bob -
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Old Feb 21, 2012, 01:06 PM
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Something else to consider

1. Autopilot - NO

2. Airspeed control - NO

3. Gyro stabilizer or any other stabilizing device that moves a control surface without direct pilot input- YES...PERHAPS, but the electronics required may be cost prohibitive. I can see the value of a "rosary" device as in "Hail Mary, Full of Grace" This would be a manual pilot command that would level wings and manage speed in a last ditch attempt to save an "I've lost it" sailplane. It could be used as often as necessary but the event would "mark" a data logger so a huge scoring penalty would be applied for using it. First it is an issue of SAFETY and secondly, it is much better than loosing a sailplane.

4. Video telemetry- NO

5. GPS telemetry - YES

6. Airspeed telemetry - YES

7. Vertical speed telemetry (Vario) - YES

8. Altitude telemetry - YES. I can forsee the time when it will be necessary to have altitude restrictions due to flying under or near certain classes of airspace. You are kidding yourself if you don't think the FAA is taking this very seriously.

9. Flight computer in chase vehicle to assist the pilot in utilizing any of the above telemetry. YES

In full scale soaring, there is a huge movement towards sailplanes equipped with self-launching propulsion. I am all for self launched XC sailplanes to eliminated the hassle and expense of a winch. I would like to see this embraced by the acceptance of a sanctioned data logger that records any use of propulsion. Therefore self-launching sailplanes would be welcomed with the addition of appropriate user rules. Please understand I am only promoting power for initial launch or use prior to the start of a task. In no way would I support use of propulsion out on task.
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Old Feb 21, 2012, 03:31 PM
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hi HLGNut,
Sure the cost of radio certification is outside of my capacity too. I do it sometime for my company and it cost you an eye to go FCC/CE. So even if I build my own radio board (based on this 2.4Ghz module LT2510 I prefer to plug my sensor board to a FrSky receiver (I have D8R) which allow me to read data from my smartphone without doubling the radio channel.
I'am happy to see that the majority here support the features I've made. Here in France, I sometime fly test the system on the slope with races in the 3 dimensions. One race would be a turnpoint in front of you (radius 15m x 50m height at elevation 0) then tp2 300m away on the left but at elevation 150, then tp3 in front of you 150m away from the slope elevation 0, then a tp4 far above you (250m elev, race in the third dim. here), tp5 and tp6 for speed and arrival. Or you can go for a few laps more. We flew this kind of race with a team of two. It is very challenging and the decision cycle is very short.
As for open sourcing, I don't know what to do with this experimental design by now. I need to finish it first. I'am waiting for my new design, but the manuf. is 1 month late now... (If someone here know the guys at http://dorkbotpdx.org/wiki/pcb_order, please...). I need to test a new little GPS very cheap chip (but good !).
I think the BOM is around 130$ for one pc but I'am not sure.

@FlyVA : I too wanted to make visible the use of a motor in the igc trace file, so one input is for the throttle pwm (Y servo cable) .
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Old Feb 21, 2012, 03:43 PM
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Originally Posted by zenoid View Post
I'am waiting for my new design, but the manuf. is 1 month late now... (If someone here know the guys at http://dorkbotpdx.org/wiki/pcb_order, please...).
Zenoid, I've ordered several boards from dorkbotpdx, always has good experience with them.

How can I help; contact me offline.

- Bob -
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Old Feb 21, 2012, 04:54 PM
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McCready speed to fly

Gents,
Short question about "McCready speed to fly", because I nowhere read this expression.

Do you already have real time airspeed measurement in the gliders and if so, do you use a computer in the chase vehicle for calculation of Mc Cready speed to fly or other kind for the pilot?
Or is airspeed measurement a new facility, an extension of the existing system?

Cees
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Old Feb 21, 2012, 05:29 PM
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Quote:
Do you already have real time airspeed measurement in the gliders and if so, do you use a computer in the chase vehicle for calculation of Mc Cready speed to fly or other kind for the pilot?
Most everyone that I know of that does XC racing here in the US, does not have any means to measure airspeed from the sailplane realtime; they do not have any polars, and so cannot do any McCready speed to fly calculations.

I say realtime because everyone has a GPS datalogger on board now and from the logs can get ground speed. Yes, I know not airspeed. Logs are generated AFTER the sailplane lands.


Quote:
Or is airspeed measurement a new facility, an extension of the existing system?
Yes, we are flying in the stone age - we just receive altitude/vario tone/battery voltage as sent out by the Picolarios or Sky Melodys that everyone has.

Sorry... but that is the way it is right now.

- Bob -
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Old Feb 22, 2012, 05:49 AM
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Bob,

Don't worry the situation isn't different in other parts of the world only fact is you do fly XC.

My point is, I think I can contribute because for many years I do fly my pattern plane (with ic engine) with airspeed control at a speed range comparable with the range for your gliders.

To show my concern, I have some data of a setpoint air speed value of 27.2 knots! (31,3 mph, 50 km/h).
I do measure this speed with an absolute accuracy of about +/- 1 knot because it is feed back for the controller.
I calculated the accuracy of a few used systems of which I could find some crusial data.

My conclusion is at an indication of airspeed of 27.2 knots it can either be a real airspeed of about 20 knots but also 32.8 knots!
So deviation can be -7.2 knots and +5.6 knots or -26% en + 21 %.of measured value.

In reality it can be some better but IMO these measurement don't contribute as much to XC flying as you expect, especially because this is only the deviation of the ttransducer and not the whole system.

So these measurement CAN be important to bring XC on a higher level but do need much more attention than until now only by voting and buying IMO.

Because I write my contribution as result of personnal know how and experiences you will understand it is not my goal to start a thread about this subject.It is only a signal to count with. Background information.

Cees.
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Old Feb 22, 2012, 06:19 AM
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Originally Posted by Aquila Guy View Post
......The pilot and chase crew already know the course heading to next turnpoint (prior to reaching the turnpoint) because they will be driving the road.
Scott
This is not necessarily true. Let's say that you've just rounded a turnpoint and are headed to the next turnpoint. The issue is that the road is not straight but is a large arc to the next turnpoint or in fact an S curve to the next turnpoint. To fly the shortest course you'll need to have the glider to the left of the road sometimes and to the right of the road at other times. How far off the road is correct ? When should you cross the road to go from one side to the other to keep the shortest course between turnpoints ? This is a matter of judgement, experience, or skill, the very things that define competition. If you have GPS data sent down realtime then you can be constantly updated on where the exact course is, thus removing that portion of the judgement, experience and skill contest.

I'm still on the fence on this one but want to point out the things that others are not to help with the decision.

Mike
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Old Feb 22, 2012, 08:40 AM
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Quote:
Originally Posted by ThermalSeeker View Post
This is not necessarily true. Let's say that you've just rounded a turnpoint and are headed to the next turnpoint. The issue is that the road is not straight but is a large arc to the next turnpoint or in fact an S curve to the next turnpoint. To fly the shortest course you'll need to have the glider to the left of the road sometimes and to the right of the road at other times. How far off the road is correct ? When should you cross the road to go from one side to the other to keep the shortest course between turnpoints ? This is a matter of judgement, experience, or skill, the very things that define competition. If you have GPS data sent down realtime then you can be constantly updated on where the exact course is, thus removing that portion of the judgement, experience and skill contest.

I'm still on the fence on this one but want to point out the things that others are not to help with the decision.

Mike
Thanks Mike. As I said in an earlier post, I have not done r/c xc yet, only going on what I have read here. The examples I have seen show the course relative to roads and I assumed that you had to follow the roads and not cut corners.

Scott
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Old Feb 22, 2012, 10:06 AM
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