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Unexplained Crash of Shinden pattern p

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Old 08-12-2017, 04:52 AM
  #1
DAVE KEPHART
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Default Unexplained Crash of Shinden pattern p

I lost two Shindens under mysterious loss of control, not dumb thumbs, equipment was tip top . After a dozen or more trimming flight suddenly complete signal failure. I have lost many a plane over the years , but this was different. Any similar experience with this particular aircraft? I love the design , best pattern plane ,hands down . Just don't want to lose another.
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Old 08-12-2017, 05:59 AM
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maustin
 
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Sorry to hear about you losing 2 great planes. Hard to imagine it's a plane issue as these have a proven track record. The more I read up on 2.4 radios the more I lose confidence in these things. I've had intermittent hold with my Airtronics radio in my Black Magic and ended up running one antenna out into the foam wing to get away from anything that can block the signal. Seems to have worked so far.
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Old 08-12-2017, 06:31 AM
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I too am sorry you lost two planes. I like the Shinden and the other CKAero planes as well.

What radio system?

How was the Tx antenna oriented, do you fly with the Tx level, top tilted down or up?

Where are the Rx antennas located in the Shinden, not just the 90 degree requirement?

The reason I ask is I too fly a Shinden with a Futaba 18sz. I lost signal on a Cuban 8 1/2 roll at center. I kept trying to fly it now matter what. What seemed about 25 feet off the ground, I finally got back controlled flight and landed.

I was immediately told by two top Futaba Team Pattern Pilots one contributor was how I held my Tx and the Tx antenna orientation, 45 degrees. The antenna was pointing right at the plane.

The second contributor was the location of my Rx Antennas. They were mounted on a solid CF Plate with no overhang. The Antennas were at 90 degrees and off the plate by an inch of foam block.

After staring at the plane when I got home and visualizing what happened, I came to the conclusion that both contributed to the issue.

1) The Tx antenna was presented to the Shinden with the weakest signal beam off the tip of the antenna.

2) The CF Plate created a barrier further weakening or blocking the Tx signal to the Rx.

Failsafe held the controls centered with idle on the motor. When the bottom of the plane was presented the signal was lost.

I now fly with the Tx Antenna pointed straight up. This translates the antenna position about 75 degrees as I hold the Tx slightly in a down position.

I have not moved the Rx antenna yet, but will. I have not had an Rx black out since (about 20 flights) but after researching the CF Plate concern I will move my antenna location in the Shinden.

I have set up a 2M Acuity using the same set up and made sure the antennas are not blocked by a CF plate. After about 30 flights, no issues to date.

Check to see if any of these conditions existed on your Shinden. Shouldn't matter which brand of radio is used. The fact that it's a Shinden is not relevant. Any plane set up and flown with either condition would have most likely resulted in a lost plane.

LD

Last edited by DRC1; 08-12-2017 at 09:02 AM.
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Old 08-12-2017, 06:41 AM
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An assumption on my previous post is that the Tx and Rx battery condition and charge was sufficient under load.

LD
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Old 08-12-2017, 08:26 AM
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DRC1, The battery condition should always be considered, but most (all?) radios now have a failsafe feature for battery condition (audible beep for the TX and programmed failsafe for the RX) which should prevent typical battery failure from happening. Mechanical failures (wire breakage, switch failure, battery disconnect) are just bad luck. I lost an airplane this spring when the battery came loose during a snap roll and unplugged. Immediate loss of control.
Sorry to hear about the Shindens. I have read a lot recently about Tx antenna orientation, Rx antenna orientation and materials that can interfere with the signal in your airplane (like CF). I think all of DRC1 advice/experience is very valid.
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Old 08-12-2017, 04:29 PM
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DAVE KEPHART
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I lost my first Shinden while rolling during a Cuban eight. Thank ya'll for the input, I will use it . I have been out of the hobby for About five years . The loss of the two Shindens back to back was hard to take, but I'm back and ready to get back into competition. I fly Advanced in District 8.
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Old 08-12-2017, 05:08 PM
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Welcome Back Dave... It was very nerve racking to put the Shinden back in the air, always wondering if there was something else. Looking back, I don't know if I ever rolled the plane away from the flight line before that contest. The winds typically come from the west in my area and the runway is north to south. I have been coached to roll into the wind. I recall at that contest I did roll away from the flight line and presented the bottom of the plane. I rolled to just about inverted when I lost signal heading to terra firma at a 45 degree angle. Very uncomfortable feeling. I was leaning on the Aileron stick all the way both ways and nothing. All the sudden it started a rapid roll when the signal was restored. Once I established wings level and landed, I changed my pants... It's like flying a free plane now... I can't imagine losing one plane like that, let alone two.

I fly Intermediate in District 4. I've been in and out of Pattern since 2007 and haven't flown/practiced often enough to be very competitive. I'm trying to turn that around. We shall see...

Good Luck...

LD
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Old 08-12-2017, 07:07 PM
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I was in attendance when this happened...

https://www.rcgroups.com/forums/showpost.php?p=37964725&postcount=17

The complete thread

https://www.rcgroups.com/forums/show...Just-can-t-win

Ken

EDIT/UPDATE; I've flown the Kaos more than a dozen times since I installed the Optima 9 that was in the Smaragd. I've had no "hits" at our club field. I don't know of anybody else that has had hits either. Maybe this was an isolated incident????

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Old 08-13-2017, 07:24 AM
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Carbon and 2.4GHz does not mix well! Best practice is to try and get the antennas away from carbon and if the fuselage is carbon you need to get the antennas outside. Having flown 4m wingspan full carbon F5J planes to the limit of visibility (tiny speck size, more than 1500m away) I have learned that setting up the antennas is the key to success! Mounting the antennas on a carbon plate is a recipe for disaster....

And yes, as someone said, NEVER point the TX antenna at the plane, carbon or not! I log my RSSI telemetry and it is interesting to see how signal strength can vary as a plane turns.

It should also be noted that not all 2.4GHz frequency hopping protocols are created equal, but that is a touchy subject that I have done a LOT of research on and have learned that not everyone understands the technology and most discussions ends up messy.

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Old 08-13-2017, 05:18 PM
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I agree that antenna location and orientation play a huge role in reliability. I found out the hard way that if the airplane contains a fair amount of CF it's best to have the antennas external. If you think about it, by having out antennas internal to a composite structure we create somewhat of a radomes with an odd shape. Radome shapes can have an affect on transmit patterns and I also suspect it could alter the signal some prior to reception. Run antennas external and it is not a concern.
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