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May 07, 2011, 06:02 AM
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Data

2G4 Reciever and 433MHz Variometer


My EasyGlider Pro electric crashed after a minute during flight #2
.
Flight #1 was a great long thermal flight up to 340m.
Few seconds after take-off #2 and switching off the engine, my transmitter noted that there was no return signal from the receiver (Jeti 2G4 TU module in my MC 19 with 8 channel EPC 2G4 receiver, long antennas).
At the same time an uncontrollable short nosedive occured.
I decided to come back and to land promptly.
During the long 400 or 500m final connection got lost again without any control surface reaction and the EG Pro lost 112 m in < 3.2sec in a, at the end, vertical dive.

I assume the fastest Easyglider Pro flight ever :-).
134km/h average speed.
Impact speed could be around 160/170km/h or more as the ship had to accelerate from normal flight speed and came down in type of a half parable...
No flutter and a flight like on rails. Very good high speed test results of my EasyGlider Pro mods ;-)!

Everything points to a Jeti receiver issue as it was definitely no pilot error...
Reason to be analyzed!

Killed:
8 channel EPC Jeti Receiver
speed controller Kontronik Jazz 55
motor Turnigy C3536 -1100
EasyGlider Pro
2 HS-82MG servos, 4 wing servos to be checked
3S1P 2200 mAh Lemon LiPo
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May 07, 2011, 06:03 AM
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EasyGlider Pro crash with Jeti 2G4 Duplex system: first analyze


Overall I can remember 5 similar incidents when flying horizontal and turning into a vertical dive without any reason when using Jeti 2G4 Duplex system.

Incident #1 occured ~ 500m away (this crash)
Incident #2 occured ~ 420m away (this crash)

Incident #3: my Tracer crash some weeks ago, occured ~ 140m away
Incident #4: end of 2010 thermal season with my Organic.
She also moved into a 200m vertical dive. No connection to receiver, lost signal sound from transmitter.
Few meters above ground connection was established again and I got controll back. No damage. Occured ~ 350m away
Incident #5: Helmuts Xperinece Pro during maiden flight last year. Serveral vertical dives, 100 - 400m away. Luckily no damage as well.


Incident #1, 2, 4 with same receiver and Variometer on board, #5 other receiver but also a Variometer on board
Antennas were placed correctly during all incidents (several successful range tests were made)
Receiver battery had 65 - 85% of capacity at these points in time
During incident #1, 2 a guy with a very cheap 2G4 Hong Kong transmitter and a helicopter quite close to the impact location

Talked to several specialists the last days:

433MHz Variometers and 2G4 receivers don't like each other in general.
Especially the 4, 5, 6 and 8 channel Jeti Duplex receivers seem not to like 433Mhz transmitters close to their own location.
For incident #1, 2, 4+5 Variometer and receiver were very close together (for the EG Pro crash on top of one another)


My (interim) conclusion:
Incidents #1, 2, 4 and 5 have a good explanation because of the 433MHz Variometer use
Incident #3 must have been a pilot error?
The 2G4 Hong Kong transmitter from the helicopter guy did not close the 2G4 band completely (!HOPEFULLY NOT!)
Get statement from Jeti (got interims feedback from Jeti's, let's see)
At least the receiver used in my Tracer will be send to Jeti for a recheck
Sell my 433MHz Variometer asap and use the revenue to buy the LinkVario from wstech.de
For very far and low distance flights with challenging radio conditions (e.g. slope: down valley fight sessions ) I will use 35MHz again until I understand 2G4 behavior in this scenarios.
Jun 03, 2011, 03:18 AM
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R8 receiver replaced by Jeti


Meanwhile I got all of my R8 receiver replaced by Jeti.
I have tested three of them over the last two weeks and I am quite sure that they are much better than the "old" ones I bought two years ago.
Since using the new R8 receivers (they have a label II/11) I had no range warning which I had quite often with the old receivers (also with no 433MHz Variometer onboard).
Jun 14, 2011, 04:01 AM
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After ~four weeks of testing the new receivers with several gliders thoroughly I did not note one issue .

I have installed my four Jeti Duplex R8 EPC receivers in my Tracer, Typhoon, EasyGlider Pro electric and Elixir.

As I do not like to fly too high (>350m AGL) the regular operation range is "only" up to ~600m...

Except Elixir I guess I had 3 to 5 hours air time with each of the other three models.


Quote:
Originally Posted by sky_surfer_fra
Meanwhile I got all of my R8 receiver replaced by Jeti.
I have tested three of them over the last two weeks and I am quite sure that they are much better than the "old" ones I bought two years ago.
Since using the new R8 receivers (they have a label II/11) I had no range warning which I had quite often with the old receivers (also with no 433MHz Variometer onboard).


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