christiaan.geyskens

Hello All,
The M346, for which Bruno Henderyckx is re-building the retracts, is mine. I asked him to look into them, since the gears simply do not work.
As we experienced it, the quality of the electric motors/gearsets are just below standard and not even fit to use in a child's toy.
Also the accompanying ECU has, as my friend Bruno says it, a mind of its own and is not useable since unreliable (although, with mine, the brakes work fine).
When I told him about my problems, Bruno from C&C Models keeps insisting that the gears and "magic box" work fine as they are, and that there really are no problems with it whatsoever.
Then why is there now an alternative (non-Chinese) gear set on offer for € 1.200, if the original works perfect for € 900? Maybe the same philosophy as with the thrust tube : buy a rubbish Chinese one for € 150, or a good German one for € 250?
I can only hope that the "new" Electron gears do work this time. Otherwise, clients buying them will have lost € 1.200 instead of the 900 euros we initial clients have lost.
Replacing the gears with a pneumatic set, as Heer has done, is from a client's point of view not really on "economical" option. Re-building them, as my friend Bruno is doing, also represents an additional cost (€ 455 for the 3 motor/gearset replacements alone, and we still have to see how we're going to make the ECU work).
It's really a pity, because, as Ali says, the model itself looks fine. We're still hoping to make it into a nice flying model, but it will not be thanks to the (original) retract set.

CDB-RAE

hello

have electron retract in my pst revision and they works really nice no pb at all.i m flying on a grass runway and sand.
i just switch up and down and that it will never go back on pneumatic and have preordered the electric brakes should arrive by the and of october
best regards
fafa

marc s

I also endorse Electron gear, having had involvement of electric gear from a production stand point they (Electron) do seem to have produced a gear system which incorporates many of the key items I feel (from experience) need to be present. The threaded shaft is supported by a bearing at the free end, and more importantly the end stops are buffered with a special plastic/rubber washer which is key to a smooth operating electric gear set.

To explain why is important. With electric motors/gearbox drives the point where the system is ordered to stop spinning the motor is normally fed back via a current spike detected by the electronic controller, this happens as the drive pin hits the end stop slot in the retract body side plates. All well and good it seems, not the case..... by the time the pin hits the end stop and the motor is stopped the inertia in the spinning parts drives the pin so hard into the end stop that often the gearbox can literally lock itself up, guess its like a car hitting a brick wall. So the gear is up (or down) and the motor is stopped, the gearbox is likely to be 'tight' and the pin is hard up into the end slot - time for gear down (or up) voltage flows, instant current spike to overcome all the resistance from gearbox and associated friction of threads etc and system stops as the current hits the threshold for the stop command and the gear is hung. You can adjust current spike levels to not trip but all this does is make the end stop even more solid when the gear hits up or down for the first time.

When we looked to design the electrics to control the retracts we designed a system whereby once the end stop was triggered the motor reversed for a fraction of a second, this effectively eased the strains and lock up and prepared the unit for the next command, it worked but was not 100% reliable, the final fix and one used in the electron units (cannot say for others) is the use of a buffer/stop at each end of the pin travel, the material is critical too, as the buffer needs to be hard enough not to deform and bind up with pin/threads etc, but soft enough to cushion the pin travel at each end so the current spike is more progressive and then the system can shut down before the whole drive locks up. Another benefit is the rubber 'pushes' the pin back so helping the reverse motion when everything kicks in and gear is triggered.

Naturally the correct gearbox motor combination is critical, the gearbox should be of planetary design not spur and well assembled, the rpm of the output and the threaded rod used to drive the pin should result in gear speeds which are 'scale' in speed, too fast and the system is going to be unreliable and low torque, too slow and the gear wont deploy in time should you have a need for an emergency landing! All told slower retracting systems should be more reliable (assuming quality electronics and parts are used).

One comment about gear speed, a few Jetpower's ago Ali Machinchy kindly helped out and flew both our P20 and EDF Stingers, these used our electric gear, whilst we cycled them at the stand before flight Ali commented (and I am sure he wont mind me saying this) that they were sooo slow (around 7 seconds for full cycle) he would have to trigger the gear a few circuits before landing Well actually during the flight he triggered the gear on the pre-landing pass and commented on how nice it was to see gear deploy smoothly and made the jet look way cooler So I guess the point here is when you test something on the bench, like boiling a kettle it seems to take far longer than you feel it should, in reality actually its totally fine........

marcs

Xairflyer

My Feedback: (1)

The eflite retracts reverse the motor at end of travel

marc s

Certainly helps....

henderyckx bruno

Did some more work on the setup that we going to use,on 3s the speed is good and powerconsumtion is around 150ma per unit.The picture will say more than i can tell.

Still i regret that one have to pay 900 euro,s for something thats actualy noth whorth a dime.

Heer

Bruno, your solution looks good !
Did you have also change the L-angel on the mechanics ?
This original chinese parts are made - so I guess - from to soft aluminum.
Brg
Fritz

henderyckx bruno

No,i did not do that,the seem ok and the position of the gear is so that there are no side-load forces on the mechanics so whe go for it and hope the hold.For now two more to go so some more milling and drilling is on the way.Grtz Bruno

henderyckx bruno

First unit ready to go into the plane......

theosoarus

Bruno... your modification will not work. you should keep the standard retracts that come with the kit... Christiaan i wish you success with the model.. I will continue with mine when I return to Australia... Thanks again for the beers, it was night meeting the famous Bruno, master model builder for Gregg V and his team of side kicks at Stunters
Cheers
Theo
PS Joris.. L39 Skymaster!

Pinnacle Aviation

Ali's M346 is back in the workshop having a new set of electron retract units fitted. The original C&C units had a gear door sequencer, the electron unit does not so I am using the powerbox cockpit that is fitted. The video is showing the door sequencing before the legs are refitted. They have been installed once already and were taken out to program the doors.

http://m.youtube.com/watch?v=i1WiPQ-xqdA

Rider-60

My Feedback: (17)

Do you use standard or reversed retract units?

Cheers
Florent

henderyckx bruno

Hello again,my modified gear is now in the plane and working,i also made the teardrop schape nav lights,grtz Bruno

zeev barnes

this scale job is one of is kind
great job Phil

henderyckx bruno

Hi there,is it posible to post Some pics of the main gear door linkage and the place where the servo is mounted on your setup.

Thanks Bruno

ziopaperone

Hello,
attached some pictures,
i hope can help you.
About electric landing set, i write in my web page,all customers that have had problems to contact us, we will repair for free to the last and improved version.
many thank
bruno

christiaan.geyskens

Hello Bruno from C&C,
Thanks for the offer to rectify the problems with the retracts, but for us this offer comes too late : we've implemented our own solutions by now.
Might have been more positive if you had made this offer when we reported the problems to you initially, but back then you decided that there were no problems at all.
My friend Bruno's (from Belgium) question was directed to Pinnacle Aviation, since they apparantly changed the servo linkages to the main doors in order to prevent their closing during flight and obstruct the retracting gear.
Kind regards, Christiaan

ziopaperone

Hello Christiaan,
i am sorry but problems is that the landing is produced not from me,
i tested the prototype for around 100 cycle without any problems for this reason i decided to produce and sell it.
Later,in the series production we have had some problems with gear reduction,out of my control,
This problem is only in a restrict number of gear,because after reported from you and another customer i tested some kit in stock in my shop and i don't found the problem.To find a solution we have lost a lot of time,
Now we upgraded the retracts with a bigger motor and other solution to prevent a high torque when the legs reach the end position,we also upgraded the electronic firmware.About main gear door servo linkage,i know that some customers used 2mm with metal clevise, i thins are too small , normally we use 3mm rods with uniball and metal gear servos,
for any other request don't esitate to contact me,
merry xmas and happy new year to all friends
bruno

Gonzalo38

Any updates on this model ?

Were the problems with the retracts ever fixed ? I'm very tempted on trying one, but if the model still has some problems that need to be fixed, I prefer to wait.

ziopaperone

Hello,
model flies perfectly, you can see also the video with EDF schuebeler inside : http://www.youtube.com/watch?v=78H0aFj3Hf4
about landing set, we upgraded the mechanics and electronic,now work without any problem.
rgd
Bruno

christiaan.geyskens

Hello all,
Sorry to say my M346 didn't survive it's maiden flight : carbon rod holding the right elevator broke during flight.
Second airframe was provided by manufacturer, but, unfortunately, that also didn't survive it's first flight.
Vertical stabilizer folded during flight due to structural failure of rear carbon tube.
Have decided not to build a third one.

http://www.youtube.com/watch?v=n1gv4gN1sq4

Kind regards,
Christiaan

garrett_mcdonal

Hi Christiaan,

Oh dear...that's terrible news. I have one on the building table at the moment so that leaves me feeling a little cold. Do you know where on the read vertical carbon tube it folded and any idea how it managed to fail? Did you notice if it fluttered just before folding?

Regards,
Garrett

christiaan.geyskens

Hi Garrett,
This is what I (and some other witnesses) think has happened.
When we examined the item in question we were surprised to find that the rear peg of the vert. fin is not a rod, but atube.

I had not noticed it before, assuming that it also was a solid rod (like all the others, wings and horizontal stabilizers).

Effectively, when you build the model, you spend little time with the vert. fin : you just screw in the servo, link it to the rudder,and that's it....... You put the item aside until you fix it to the fuse before you go flying.

If I had noticed (and I could kick myself now for not doing so), I would have filled the tube up with a wooden dowel or a carbon rod, to make it solid.

Because, when you fix the vert. fin into the alu. retaining blocks and tighten the screw, the rod/tube is squeezed tight. I'm afraid that, in our case, being a tube, the item effectively gets a bit squashed and is weakened by it.

Being a really large fin, the tube is not strong enough to withstand the loads during flight and breaks. You can actually see the shape of the edge of the alu. retaining block in the breech-line of the carbon tube.

Since the vert. fin is now attached to the fuse by the forward carbon rod only (solid, but much smaller diameter), it folds under the pressure.

In the case of my maiden flight, I had a lot of down-trimming to do after take-off. I had reduced throttle, but, unnoticed by me, the airspeed seemed to be too much reduced for the model before taking the first turn. To my surprise it went into a mild spin (in my opinion, the model will stall rather easily, because the airspeed was not really that low). I think that this occurrence, normally rather harmless, already put too much strain on the tube in question.

I think the final result is obvious in the video.
Also, just to check my theory, I retro-fitted the vert. fin of the first airframe (which had survived unscathed). I pushed it laterally until the rear tube effectively broke, and it really didn't need too much pressure. Like its predecessor the fin then folds over, the only reinforcement being a horizontal rib about halfway.

So, to conclude : before you do some fancy flying with the M346, please make the rear carbon tube of the vertical stabilizer solid.
Regards, Christiaan

garrett_mcdonal

Thanks Christiaan,

I'll pull my fin tomorrow and check but I suspect you are 100% right that it is a hollow tube. I'll hysol a solid inner into place to prevent it from being crushed by the lower clamp. Did the factory respond with why one of you stabs failed?

Regards,
Garrett

christiaan.geyskens

C&C was so kind to give me a new airframe after the first mishap, agreeing that the broken elevator rod was probably a fault in the production.
However, C&C will not accept structural failure of the vert. fin for the second crash; according to them it was caused by my "extreme flying" resulting in loss of control, and the carbon tube was broken on impact.
Regards,Christiaan