Parkzone Trojan crashed - any ideas why????

Kashkai

I haven't flown in over three weeks. So this morning, I got up, saw it was a nice calm clear morning and said to myself "I need some flight time to clear my head". So I took my T28 out to the park for a flight session before work.

The sun was just rising and I had the park all to myself so I was looking forward to a good flying session. I put in the larger 2200mah battery (fully charged last night) as I wanted a long session (my smaller 1800mah batt seems to run out of puff too early imo) and I sent the Trojan up. After some gentle circuits to get the feel of flying again, I did some nice loops and rolls to exercise my Trojan. I then brought her up to altitude using a series of climbs, level off to pick up speed again and climb again until she was a speck and then I brought her down in a spiral dive and then levelled her out again. She was flying beautifully and all appeared to be well.

I was bringing her round for a low fly by in a gentle bank at about 80 foot altitude when I realised that she wasn't responding to my Spectrum DX5 2.4ghz tx anymore. With a sickening feeling in my gut, I chopped the throttle and tested the ailerons for control but it was no use and she went in about 150 feet from me. I took the long walk of shame over to the crash site to see how bad it was. The nose had broken off, the left main wheel was snapped off the wing and the left wing itself has a crack from the leading edge halfway back to the trailing edge. The cockpit had come away so I could see the rx. The orange light was solid orange which surprised me as my initial thought was that I had had a loss of signal. So this appears to rule out a tx/rx signal failure. I then tested the controls and the ailerons, rudder and even the engine in the detached nose worked.

What else could have caused this loss of control? My only other conclusion is that I pushed the battery too far and it went beyond lvc and this caused the loss of control. However, I hadn't noticed any of the usual warnings such as the motor pulsing and lack of power for climbs etc. It was a cold morning here in Dublin but its been colder so I don't think the cold sapped the battery faster than normal. I don't have a volt metre to check the batt but I do have a new Quanum telemetry system that provides feedback on the battery's voltage. "And why weren't you using that this morning?" I hear you ask. Well because its still sitting in its box as I have been tied up with other things and haven't had time to unpack it or test it out. Can I use this to check the battery's voltage to see if it was a loss of power that caused the crash?

To sum up,
- the loss of control happened when the plane was relatively close to me (it had been farther away and much higher just prior to this and everything appeared fine),

- I don't know how long I was flying but I don't think it was more than 10 minutes (hard to keep track of time when you're flying though),

- the rx light was glowing steady orange so it doesn't appear to be a signal failure

- the control surfaces still worked when I tested them when I was close to the plane crash.

I'm confused as to what happened tbh. I really didn't want to start my day by crashing my plane due to some unknown problem.

Bruthal

Hard to know the cause of that. The low voltage cutoff only usually cuts out the motor and not the power to the receiver. If the receiver lost power and it returned then the orange lights would be flashing on the receiver, so if the receiver light was still steady then it did not lose power.

But if the receiver did somehow lose reception the orange light would still be steady.

A test to do to see if the receiver is the updated type with the power loss flasing indication is to power the system up, and check all controls are working. Then switch off the power to the receiver and switch it back on with the Tx still on the whole time. If the receiver lights flash then it is the updated one and would indicate nothing was wrong with the radio link as it was steady after the affected flight.

If the orange light does come back on steady then it shows the radio receiver may have lost power momentarily in flight.

Kashkai

Its the updated model AR6200 alright Robbie. I did this test when I first received the Trojan, i.e. after powering on the tx, connecting the battery and checking everything was working, I disconnected the battery and then reconnected it and the rx light started flashing indicating a "power failure" and loss of signal.

The rx orange light was solid following the crash which has me perplexed. What else could have caused this? Some guys on another forum have suggested a problem with the esc and suggested that I fit an external UBEC that would still supply power to the rx and thus the servos in the event of an esc failure. At least this way, I could still make an emergency landing and avoid significant damage. In a way, I was kind of lucky that the loss of control happened when the Trojan was doing a slow gentle bank so the crash, while bad, wasn't catastrophic. A few minutes previously, I'd had her up at around 300 feet or so and put her in a screaming dive for a loop. If she had gone out of control at that point, I'd still be picking up pieces of foam:eek:.

She's a great plane to fly btw and despite my crash, I'd recommend her as a good step up from a trainer. Did you follow through with buying one for your son?

Cookie_Monster

Interference from another transmitter (model or commercial) perhaps?

coolwings

When you reduced the throttle, was the motor already off, or did the engine throttle down instantly, or was there a delay and then it throttled down?
After the motor cut, was there any servo operation.

Kashkai

coolwings wrote: »

When you reduced the throttle, was the motor already off, or did the engine throttle down instantly, or was there a delay and then it throttled down?
After the motor cut, was there any servo operation.

Tbh its hard to know for sure. I had the throttle at 50% or so when I realised she was out of control so I cut the power in an attempt to reduce the impact damage. The prop on this model windmills even when the motor is cut so the prop can still give the impression of turning when the power has been cut.

There was no servo action whatsoever when the motor was cut. I tried the ailerons to level her wings out and then gave some up elevator to pull her out of the dive but nothing happened on either occasion. I had approx 5 seconds to try to regain control but nothing worked for me. However, the servos did work when I tested them after the crash.

I'm thinking the problem might lie with my Spectrum DX5 as this is the second time this year I've lost control of a plane for no apparent reason. My Radian was up about 400 feet vertically and about 100 feet horizontally from me when I lost control of her and she flew away last June(later recovered remarkably intact btw). Is there a way to test this tx apart from a range check? The batteries in it are fresh energiser lithiums so thats not the problem either.

coolwings

Hard to guess .... intermittent disconnection from a bad wire/cracked circuit board maybe.
There is a pause in 2.4ghz systems while they "reboot" after power loss, which could (possible) explain working afterwards, but temporarily dead after a "blink" in power supply onboard.
It's only a speculation...

You could try setting up and wriggling wires, twisting, shaking and inverting all equipment one item at a time to see if you can induce a repetition on the workbench. Intermittent faults are the hardest to find.

Bruthal

Prosperous Dave wrote: »

Its the updated model AR6200 alright Robbie. I did this test when I first received the Trojan, i.e. after powering on the tx, connecting the battery and checking everything was working, I disconnected the battery and then reconnected it and the rx light started flashing indicating a "power failure" and loss of signal.

The rx orange light was solid following the crash which has me perplexed. What else could have caused this? Some guys on another forum have suggested a problem with the esc and suggested that I fit an external UBEC that would still supply power to the rx and thus the servos in the event of an esc failure. At least this way, I could still make an emergency landing and avoid significant damage. In a way, I was kind of lucky that the loss of control happened when the Trojan was doing a slow gentle bank so the crash, while bad, wasn't catastrophic. A few minutes previously, I'd had her up at around 300 feet or so and put her in a screaming dive for a loop. If she had gone out of control at that point, I'd still be picking up pieces of foam:eek:.

Well if you had an ESC failure then the motor will usually stop and not start again, and usually the power to the receiver will also go, but the power to your receiver was never lost if there was still a solid orange light when you recovered the plane. I have a seperate UBEC in the cularis i have. I have the flight battery powering the ESC and the flight battery also Y leads to a JST connector to power the UBEC (voltage regulator is more technically correct id say) which powers the receiver.

I had a similar problem on a AR7000 a few months ago, it was on the t-rex 600 and the cyclic seemed to slightly change itself now and again, not something i was very at ease with. It turned out to be a damaged circuit board on the satellite part of the receiver. I got a new satellite part and that was that.

Anyway power loss in the receiver can be ruled out id say. Now loss of signal link between the radio tx and rx seems likely for what ever reason. For instance, if the radio was put into range test mode the plane would lose its link around 40 - 60 meters away, and nothing would show up in tests i.e no flashing receiver lights etc. This is not what would of happened, but what im getting at is if there was a problem with the transmitter transmitting then it would be a hard one to find. Radio interference is always a posibility, although in 3 years using the DX7 i have never seen a single glitch yet. But its not impossible.

Another slight possibility is loss of power in the tx itself, the DX5 and DX6i both use AA batteries, any possibility there could have been an interruption in power? I used rechargeable AA`s in one and noticed they were very slightly wider in diameter than disposable AA`s and were such a tight fit that pressing on the battery cover caused a battery to break contact from the terminals and then re make contact intermittently. This would cause that to happen there also.

Did you do any range test after the crash?

She's a great plane to fly btw and despite my crash, I'd recommend her as a good step up from a trainer. Did you follow through with buying one for your son?

I got him a DX6i radio and case for it, thats about it id say, the dollars are tight this year. I flew the parkzone p51 early this year, a fella i know got one, amazingly smooth.