Loss of control

[Spice Cat]

It happened thus,

Off to the field today with my newly re engined beloved Calmato 60.

Three flights with her and she was as good as ever. Then it happened; total loss of control and she spiralled in. I cannot say for sure but I believe that the engine pitch did not change so the failsafe was not activated.

The set up was;

AR500 rx linked to an Orange module on my Taranis.

Power via a 3s 1300mah LiPo via a switch regulator.

Heavy duty Futaba switch.

At first I thought it was a loss of signal but for the failsafe not activating indicates a loss of power. Unless I have missed something obvious, I am thinking that the voltage regulator possibly went as the battery was good and fully charged.

Now I have other models with voltage regulators and am seriously considering moving the regulator out of the loop. I have considered using a 6.6v LiFe rx pack but some of the servos I have used, HXT 5010, are rated for 6v and I read somewhere that it means exactly that. 6v !

To check this I have connected one to the rx pack via a servo tester and ran the oscillation programme for half an hour. I checked the output and it was 6.6v so it appears that these servos can take the additional voltage.

Any thoughts??

Edited By Spice Cat on 22/06/2014 14:53:36

[Piers Bowlan]

I was surprised when you said you were using an AR500 Rx in what is quite a big model, - your Calamato 60. I know that the AR500 is billed as a 'full range sport Rx' but reading various forums it does seem to have some issues, according to some users. Here. Having said that, I use one in my old 1.7m Kyosho Stratus and I have never had any problems with it to date, maybe I have just been lucky.

[John F]

I would have thought the Rx to be perfectly capable with this model. The link sounds like a nice bit of Spektrum bashing rather than anything to worry sbout

The spiral could point towards a snapped linkage somewhere? Have you checked the wreckage for links coming off or, as I have personally done, forgetting to screw the servo arm to the servo.

Edited By John F on 22/06/2014 15:32:09

Edited By John F on 22/06/2014 15:35:22

[Phil 9]

should be easy to test the voltage regulator. It is not a bad idea to use heat shrink on the connectors

[Ady Hayward]

Hi Spice Cat,

I'm sorry to hear of your mishap. quite gutting when you have a good model and she goes in like that. I would agree with you regarding total power loss. It certainly points that way if none of the other flight controls or throttle worked on the spiral down. Is there any chance that the regulator overheated. Being an IC setup would suggest there would be no air inlets for cooling as is the norm for most electric models, thus the chance that if the regulator is confined to a small area and no cooling it could get quite hot whilst powered up. If the electrics survived intact give them a good test and see if you can recreate the problem.

Adrian

[Cuban8]

Probably a good idea to have a small capacity battery in parallel with the regulator output (via Schottky diodes and with a slightly lower voltage than the regulator) to act as a backup in case of regulator failure.

[Biggles' Elder Brother - Moderator]

What exactly were you doing when she dropped out of the sky SC. Were you turning, perhaps pulling out of a move? Were you slow and holding the nose up?

You see what you describe could just be a deep stall.

BEB

[Spice Cat]

BEB,

You may have put the cat among the pigeons. As I recall it was a slow turn to the left at normal speed then the left wing dropped, no response to aileron or rudder. Conditions were a four mph wind and bright sunshine. I have flown this model on a number of occasions and never had this problem before. It was about one hundred feet up at the time and enough for me to try all controls without success.

As for linkages, there is not enough left to establish this. A real shame as this was the model I rescued from the top of a tree (well the tree surgeon did) and rebuilt her.

Is it possible to have a back up power system then??? Cuban 8's idea sounds very interesting unfortunately I haven't a clue what he's talking about. Do larger models have a back up system??

On the lookout for a replacement by the way.

Regards

[Biggles' Elder Brother - Moderator]

In a deep stall you can very well lose all control effect from the ailerons, the elevators and even the rudder. The flying surfaces are simply not functioning in this condition, so that fits your description. The comment about "spiraling" is also a common stall feature - one wing let's go before the other, drops and the model enters a spin.

Any attempt to now use the ailerons will be completely ineffective. The natural impulse is to pull back on the elevator to try to pull out. But if that has any effect at all it's actually to make the stall even deeper. The only way out is to apply opposite rudder in an attempt to stop the rotation, then to push the elevator stick forwards. The problem is that this is the very last thing to want to do. You're in a dive, headed to the ground and you have push in down elevator!

But its the only way you are going to get control back. The down elevator makes the dive steeper, faster, and re-establishes proper, unstalled flow, over the wings. Only then will the lift and the control return. Then you can gently pull out - provided you have enough height left!

(Believe me I have very recent experience of this - just this weekend I stuffed one in due to this effect. Sadly I was very low and didn't have time for the spin recovery. I was just at the "centralising the controls" stage when the ground intervened!

So, was it a stall you experienced then? We'll never know for sure. But on the basis of what you describe I wouldn't rule it out. You were slow, and turning, you may have had more elevator in than you realised and she just bit you!

BEB

[Paul Marsh]

I had my Acrowot lose control at Greenacres this weekend. Flying normally, then /some/no control. Was on Futaba, battery still fully charged.

Felt like I was getting interference, as I could almost make the model do something, but wasn't responding.

Rx was a Futaba 617 and 3300mah 5-cell battery (87% charge remaining). Gear was still powered up when I picked it up, although it's damaged, the fuselage is undamaged, apart from u/c plate ripped out and some minor damage to wing and cowl.

[Trevor Rushton]

Paul, I had a virtually identical experience with my Calamoto this weekend. 3rd light of the day and plenty of capacity left. Took off normally but ran into problems downwind, with apparently no/ some control, managed to turn back but could not clear a belt of trees. Eventually managed to recover the airframe with surprisingly little damage. Rc gear now working normally.

There was one other model flying at the time and I wondered initially whether there was some interference; concluded it was unlikely and it was more probably the case that I had lost orientation, by the time I had managed to turn the aeroplane was a long way downwind, I am not even sure if the engine was running, but it's also possible that it had cut but that with the other model going I had not noticed.

[Piers Bowlan]

So possibly stall/spin accident or an overheating voltage regulator? Either way as the model is now sadly in bits, for the sake of the cost of a stamp I would be tempted to post the receiver to those nice people at Horizon Hobby to check it out. If there are any issues with it they will more than likely send you a new one FOC. If there wasn't a problem with the receiver before the accident there may be now, post crash. Just a thought.

What make of voltage regulator are you using by the way?

I lost an ACE RC Puddle Master some years ago after it span-in when the rudder servo failed. The signal wire had become detached from the circuit board inside the servo (dry joint?) resulting in the servo giving me full left rudder which was unhelpful in a rudder/elevator model! I still had elevator/throttle control (not that it was any help) so not the same situation as you Spice Cat.

[Cuban8]

Is it possible to have a back up power system then??? Cuban 8's idea sounds very interesting unfortunately I haven't a clue what he's talking about. Do larger models have a back up system??

Re battery back up using Schottky diodes...........**LINK**

 

Edited By Cuban8 on 23/06/2014 07:32:21

[Frank Skilbeck]

A couple of other things to check

1) There have been some reports with some modules in the Taranis that the pins don't fully engage, could this have happened, I.e the module lost the instructions from the Tx

2) On one of my planes using a 5 cell Nimh battery I was surprised when the low Rx voltage alarm went off on the Tx when setting up the plane, I thought it was a duff battery so bought a Lipo and regulator and it did exactly the same, turned out it was a faulty switch which had very high resistance.

3) The AR500 did have a reputation for locking out (but the 2 I've got have been rock solid, touch wood, using my DSM2 Dx6i) so worth sending it to Horizon for checking.

Edited By Frank Skilbeck on 23/06/2014 07:43:40

[YakMad]

Scorpion do a battery backup it simply plugs into a spare rx socket, if you get a Regulator or battery failure it kicks in.

**LINK**

[Spice Cat]

Some excellent stuff here, thanks.

The regulator I have used is one from HobbyKing.

As for the rx, I'm afraid there isn't much left for Horizon to check. I am in the process of swapping all of my rx's to Frsky ones but the postal system from HK seemes a little bit bunged up at present. I have a shipment on Malaysian Air at the moment and apparently they are suffering some delays.

Many thanks to those who have taken the time to reply.

Cuban, I was taking the Mickey, it's just I am about as electrical as a box of matches!!!!

Regards.

[Bob Cotsford]

If it was a radio issue not a deep stall, If failsafe didn't kick in then I would think it was an airborne pack power supply problem rather than the transmitter (you did have failsafe set didn't you?).

4 or 5 standard size servos in a sports model are unlikely to overload a 5A switched mode regulator, far more likely would be either an intermittent battery connector fault or a dodgy switch. I've had dodgy Deans copies and 3.5 bullets, and only recently had a 'quality' switch that failed to switch on an on-board glow system at 1.2v!

[Spice Cat]

Posted by Bob Cotsford on 23/06/2014 12:40:30:

If it was a radio issue not a deep stall, If failsafe didn't kick in then I would think it was an airborne pack power supply problem rather than the transmitter (you did have failsafe set didn't you?).

Yes Bob, failsafe was set. It's probably the one thing I double double double check when setting up and periodically switch the tx off to check it' still working. I do set it to stall the engine rather than idle. Hopefully this is correct.

Wings and Wheels this weekend and I will be on the lookout for a replacement.

Regards.