Bang........

[Gazzer1uk]

Hi guys, long time since I posted, but this morning......

I bought a used Trex 600N airframe off the very delightful Mr Gixerman, and then decided to go flybarless, having smashed my previous flybarred 600N to bits....... Now, I bought a DFC head to convert to flybarless, I think it was previously a special edition or LE airframe. Bought a Beast AX AR 700 and spent days and days trying to get it set up, the very helpful Mr WaveyDavey spent a lot of time over the forum helping as did some others.

Anyhow, so frustrated I got with everything appearing to work but the tail rotor servo seemed very slow (JR 3900g), that I shelved it to go back to it...... Well today I thought bugger it, let's see if the engine runs, let's see what the tail does........

The engine started on the 3rd go, stalled, started immediately... woo hoo, all going good...... so far...... Ran up to half throttle, not a vibration in sight, looking good, but the rudder seemed completely ineffective........ I gave a little more throttle intending to make it light on the skids so I could see if the tail was going to do anything then WHAM.........all stop!!!

It flipped on the ground and I thought bugger......... When I got to it, the engine was stalled, I could hear servo's going round and round.

Anyhow, got home, and all 3 cyclic servos (JR DS 3805) have stripped gears, spectacularly so....... but there appears NO other damage to the airframe, including the main blades....

So there's a few bits that baffle me, whilst spooling up, the rotor disc was working correctly in regards to direction of travel...... what caused it to flip over? Having done this, why did it strip all gears, that's a lot of torque being applied to strip all on the cyclic controls..........? Why is the tail ineffectual or slow........???

Is anyone kind of local to Southam in Warwickshire (CV47) and an expert in Beast X that I could consult with once the gears are sorted and its reassembled?

Hope someone is out there I am convinced its a configuration/set up issue..... and I think I need to see someone who knows their way around the BeastX to get me in the right level of thinking..... and kind of face to face rather than over the forum, but as ever any help would be really appreciated.....

I thank you in advance!

Gaz

[Granpappy]

I think DFC heads are a lot more rigid and transfer a lot more energy to the servo arms in the event of a blade strike, hence stripped gears. Flybarred heads would probably have just popped the linkages. The whole event sounds like radio interference but I guess these days that is not possible unless your receiver links to someone elses transmitter. Beyond that I am at a loss. Sorry it happened.

[GIXERMAN]

firstly what pad was you using for beastx

[waveydavey]

Gaz, it might be a bit of a trip but you're more than welcome to come over to MK and I'll go through it for you and get it flying. Let me know

[GravityKills]

Is it possible that you put a blade on the wrong way?
Probably not, just speaking the unspeakable ...

[tomatwalden]

If they tail isn't working properly, did it simply spin around on spool up and tip over?

With regards to the tail - I assume you've set the tail endpoints in the AR7200BX?

[Jez N]

I'm in leamington. Don't by run beastx now but used to and can probably offer some advice. Not around next weekend but pm me and I'm sure we can arrange to meet up when you have it fixed again. Fresh pair of eyes may help see what the problem is.

[jimmyhorns]

I betting reasonable money that it got stuck in a positive feedback loop because the correction was in the wrong direction.

Although the servos will move in the correct direction when you move the sticks, so the swash moves as expected to stick movement, the FBL response to a change in attitude needs to be the opposite to the movement that has occured.

If the heli started to tip forwards slightly for example, just a degree or so, the FBL adds a correction to stop that rotation, but if it is sensing in the wrong direction it will add correction in the wrong direction, making a few more degrees of rotation, so it thinks - crap i've rotated even further now, so I need even more input.

The thing does this so quickly that in half a second after lifting off, or even trying to go light on the skids the thing tries to destroy itself..... Ask me how i know

[dieselcarb]

I betting reasonable money that it got stuck in a positive feedback loop because the correction was in the wrong direction.

Although the servos will move in the correct direction when you move the sticks, so the swash moves as expected to stick movement, the FBL response to a change in attitude needs to be the opposite to the movement that has occured.

If the heli started to tip forwards slightly for example, just a degree or so, the FBL adds a correction to stop that rotation, but if it is sensing in the wrong direction it will add correction in the wrong direction, making a few more degrees of rotation, so it thinks - crap i've rotated even further now, so I need even more input.

The thing does this so quickly that in half a second after lifting off, or even trying to go light on the skids the thing tries to destroy itself..... Ask me how i know

although I don't know how these things werk that was exactly what I was thinking had the same thing on 250 dfc with align 760 thingy it got removed and got a vx1 now but not touched it yet

[Gazzer1uk]

hi guys,

many many thanks for the quick and useful answers, and of course the suggestions. So just to confirm, blades on the right way, model did not spin but was stable until the flip. I didn't mention we did have a headwind that was quite strong but not overly gusty....... I could go with the suggestion of feedback loop but had genuinely spent a lot of time checking that, but not to say I got it wrong. It was and is still the tail that is furhter vexing me......

So I have had two fab offers of help locally and MK. Wavey has been so helpful it would be nice to meet up and I can bring a 6 pack or similar as a thank you, its only a short hop to MK from here. Jezn, that too really kind, can I keep the offer in the bag, I just think Wavey has spent quite a bit of time helping me earlier that it would be the decent thing to make the effort to go over and find some sensible compensation.......

Just trying to order up the gears...... if Only I could remember my password!!

Cheers,

Gaz

[Gazzer1uk]

Damn damn and double damn then...... So I ordered up 3 replacement gear sets (Ebay Fastlad as it turned out) and replaced the first set... the servo once energised shot to the left and stalled big time, no matter what I did after in moving the pot backwards and forwards, did the same....... second one, the servo motor just turns round and round and round.... gave up on the 3rd... so these were JR DS 8305's..... what's a decent JR equivalent of the day?

[waveydavey]

Gaz, just reading up on servos, they're only 4.8v. What are you using for power

[Gazzer1uk]

Hi Dave,

no no changes to power system from before though it may be a different regulator it is the Align regulator with glow switch. So using a 2s lipo, I have a voltage regulator for the tail servo but these ones are from the Align regulator no previous issues when it was Spektrum Rx and JR gyro, and was all working on cyclic servos prior to flight attempt...... Any thoughts on new JR servo type pretty sure these are now buggered Gaz

[waveydavey]

Seems strange, the Align reg with glow is 6.0v output I think from memory. Maybe just knackered the servos over time mate. Can you remember what settin the BeastX was set too for frame rate etc

[Gazzer1uk]

I can't remember but I did set it up according to the table in the BeastX manual....... I think that given the blades appear intact, the energy of the topple over was taken by the servos!!! And either there is something different about replacing the gearset back into a digital servo that I don't know, or frankly they are buggered..... going with the greater likelihood of the latter, keen to find out what replacement servos (pref JR) would suite the beastie, which is a Trex 600N converted from LE to DFC flybarless..... nearly!!! Cheers, Gaz