Stalker Vs Eagle Tree Pro

[Mazzola gerolamo]

Hello,

I made several tests between stalker radar gun against telemetry Eagle Tree pro.
Eagle Tree pro really accurate.

best

Gery

[Bob Hopman]

Hi Gery,

2% is good... although this is at lower speeds. I am interested what difference it will give at higher speeds. The Eagle Tree system writes of a higher sample rate of 10hz with an aditional expander... how does the system look like you're working with?
Can you export all data after the flight?

Regards and happy holidays,

Bob

[Mazzola gerolamo]

Hi Bob,
telemetry works very well, I have the version pro with sailplane variometer sound
transmission 433 Mhz, (Hobbycity.com have version 2.4 Ghz 900 Mhz with very good price).
the receiver can watch: volt rx ,g-force, speed ,altimeter ,temperature ...............Real-time and maximum values,
alarm sound speed minimum maximum........there is the USB port
download data to your PC and display.
difference in speed over 350Km / h 4 % to 7%
more 'or not depends on the detection of radar gun stalker
with radar you have not the certainty of detection point
flying all with a standardized system that would be very interesting

Best
Gery

[Bob Hopman]

Hi Gery,

thanks for the quick relpy!

Can you plot waypoints in something like Google Earth?
Very interesting to see those G-forces! They are not that high...

I like the extra pod you made for the equipment, although how is receiption in the carbon fiber case?! I can amagine, that the GPS signals are not perfectly seen by the sensor?

by the way.. can you also plot the current drawn by a servo, or more servos during DS? It would be interesting to know, what kind of loads can be seen on the servos... maybe we can see that the servos have been oversized... and we could live with smaller ones instead :)

Regards,

Bob

[Tim Medhurst]

Hello Gery,

thank you very much for the interesting data.
I'm particularly interested in the g-forces. Could you please
plot just the vertical acceleration and speed on a larger scale?
That would be of great use to me.
Thank you!

Regards
Tim

[Mazzola gerolamo]

Hello Gery,

thank you very much for the interesting data.
I'm particularly interested in the g-forces. Could you please
plot just the vertical acceleration and speed on a larger scale?
That would be of great use to me.
Thank you!

Regards
Tim


Hi,

program http://www.eagletreesystems.com/Support/apps.htm
+ files

Best
Gery

[Bob Hopman]

Hi Gery,

Thank you very much for the Link and the Data! I just installed the software, but it seems it needs a logger to activate the setup. Did somebody else succeed?

Regards,

Bob

[Bob Hopman]

I just looked at the Data... it is a space separated database. I imported the file in Excel and took out one of your fastest laps! Speed scale on the left, G Focres on the right bar...

-> some remarks in advance! The time base is in seconds! I looked at the data it records in 10Hz frequency!!! Very impressive...
-> I inserted the data in Excel 2007 format including charts

@Gery, you did not have the GPS activated in this log file did you? I saw, that the GPS data was all on level 'zero'. Was the speed messurement with the pitot tube? I inserted the datasheet of the GPS Expander they are offering now!

Regards,

Bob

[Tim Medhurst]

Good job Bob, thank you!

Tim

[Christoph Meier]

Which direction is Y and X to the plane? Very impressive that they have a sensor which measures this high g-forces...

How much wind speed you had?

Regards

Christoph

[Tim Medhurst]

Christoph,

the y direction is the vertical axis it seems.
The x axis isn't certain, but there is a cross couple between y and x,
you can see it clearly in the zoom. This could happen if the sensor is not aligned exactly with the aircrafts axis, leading to a reading in x when y acceleration takes place. A few degrees of misalignment are sufficient.


Auf deutsch:
Es scheint eine leichte Kopplung zwischen X und Y zu geben, wahrscheinlich weil der Sensor nicht 100% mit den Flugzeugachsen fluchtend eingebaut war. Bei Beschleunigungen werden die anderen Achsen dadurch auch angesprochen, auch wenn dort keine Beschleunigung stattfindet. Sonst kann ich mir die recht hohen Werte und die gute zeitliche Übereinstimmung mit der Y Richtung nicht erklären.

GrußTim

[Mazzola gerolamo]

Hi

sensor horizontal side Y, vertical X but certainly I do not remember X was mounted in the contract because all 'start registering in -1 marks should be 1 Earth's gravity. I think that the 'intersection of the axes is due to the' inclination of the model during the flight

Best
Gery

[Bob Hopman]

Hi,

You can easily see (in between red markers), that during DS the factor between GForceX and Y is 'nearly' constant (green in the graph) where as GForce Y is increasing rapidly. Outside the DS the change in Flight situation makes the factor changing as well more extreme...

Nice infos... :-)

Regards,

Bob

[Christoph Meier]

Happy new year!

I only know the coordinate system of ground vehicles, there you have x to the longitudinal, y to the lateral and z vertical.

If I take this coordinate system for a plane and go through a corner, I can imagine that you will have also y forces. The true G-Force is the vector between y and z. But anyway, very interesting that you have lower forces than I expacted at these speeds.

Badly we can not filter a complete, singel full DS circle. Because it would be interesting to see what the pitot is measuring in the diffrent sector of the circle (becuase of wind speed). Next time we will need a IR beacon signal which marks in the datas a fixed position ;) (Racecars do the same at the start/finish line on the track for their data acquisition). But anyway, we can see very nice how you increase the speed (and g-Froce).

So if the pitot is calibrated correct and works normal your top speed must be min.:= "Top Air Speed" - "Wind speed"?! Did you compared it like this to your stalker?

Bob could you please also convert this datas that I can open it with Excel2003?

Exist a technical data sheet of the eagle tree g-force sensor? Maybe somebody also now where I can buy a electronical component for g-force measuring? Because I would like to adapt it to my Unilog.

Thanks!

Christoph

[Bob Hopman]

Hi Christoph,

I converted it into .xls for Excel 2003, see attachment!
I looked at the graph (speed in green). There you can recognize a pattern (in red beneath the green line) of 4-5 seconds rounds. This would mean the small run was 5 circles getting it to max speed. This pattern can in some way been found again if you look at all the data. The drop in airspeed would be the turn, probably... but I'm not sure which valley, the lower or the upper, is the bottom or upper turn... if you consider the graph as it is and the plane exits the circle at top speed into the sky (I don't think the run would end in a downward exit :) ), then the deeper valley in the pattern would be the upper turn. what do you think?

Regards,

Bob

[Christoph Meier]

Hi Bob!

if it is like you said we have one corner where we loose lot of speed and one where it is not so much....

What else do we know?! If the plane comes up over the edge of the hill we should see a drop to more airspeed because of the wind against the pitot and after the turn less speed because we fly in same vector of the wind - if we do not increase speed. But we do so... I hope ;)

What happens in the vally turn?! If we catch the rotor correct we will have no air speed drop because of the wind speed, just because of the cornering. More or less speed because of the rotor + drag?

If I start analysing data I usually look first into g-datas because there we have no (less) other influence like airspeed (ok, shaking becuase of turbulences). I did in the diagram below. I marked the extrem points in lowst G. To know where is the vally turn we usually need to know the flight style. For me it looked like Gery flew after one hard turn streight and comes back with a rounder/ long corner.
While he is coming from this longer corner we see a big jump in the speed, while hard cornering it goes again down and have a similar level after this corner. Maybe this jump comes from the wind speed... If we look after the last green line I've painted he flys again one corner maybe this is the lower one?! But I don't know. Gery have to give us more impressions about his spot and flight style...

But it is like any time in alanysing data... you see what you would like to see ;) But what is the truth?! And we disregard that the pitot is barometric measured - so maybe influence under G-Force!

What I'm wondering is that we only see X-Forces while hard cornering. Gery, what you are doing there ;)

Next time IR beacon signal and video analysis (syncrone to data) please :p

Kind regards

Christoph

[Bob Hopman]

Hi Christoph,

never looked at G-Forces so much.. ;) But I guess you make a good point, looking at thos first. The highest G-Forces both X and Y can be found in the blue marker in the next graph. Still thinking somebody will leave the DS circle going up in the sky, the last turn would be a bottom one (might be nearly a flat one, but it is the valley one I think). Therefor the top turn produces the hardest G-forces? right? The bottom turn even seems to have the opposite... i.g. lowest G-forces, both X and Y?! So this would be the rounder curve you're talking about!
The airspeed is very difficult to examine... it should differ on each DS site & weather you're flying...

Regards,

Bob

[Christoph Meier]

Hey Bob!

Not sure if I understand you right... You mean the positive G is the vally turn? This would be not right: In both turns the G will go in same direction. That we have negative influence comes from correction (down elevator) on the "streight" or turbulences.
In a car where you drive left and right corners you have lateral negative and positive G but in a plane where you fligh this type of corners you will be pushed every time "in your seat".

I have take your graph and market the rounder corner with the green lines. The "streight" red. I've also tried to paint a possible flight line over the diagram. But how this circle is positioned to the moutain I can not tell you. If you watch G datas it is very impotrant that you filter the data and do not watch to absolut maximums. The gradiant must be something like I have painted in the diagram. Else what you see are turbulences and measurment mistakes.

I think the last blue marke is the top turn where Gery pushed very hard and goes down to the vally again and then do not push realy hard in the lower turn and goes out of the circle. But therewith I'm not sure.
We have extreme G here because of extreme cornering! But also the last G after the maximum mark you have set is a extrem corner!

Gery where do you push harder top turn or vally turn?

[Christoph Meier]

Ups, hier das diagram...

[Bob Hopman]

Makes sense! ;)

Ok... now Gery has to inform us :D

Regards,

Bob

[Mazzola gerolamo]

Hi,
sorry , let me Asked Questions precise about what he would like to know
I am very hard on the tail plane in DS slope, Mount cumeta condition in strong wind is turbulent, the my hypothetical trajectory you see on the picture, the style of flight on video.

best
Gery

[Christoph Meier]

Exist a video of this fleight with measuring euquitment? Where I can find this?

Regards

Christoph

[Mazzola gerolamo]

Hi,

I'm sorry but no video

Best
Gery