P51D Mustang

Scratch built or ARTF.
How are you getting on?
deedubs
Posts: 22
Joined: Mon Jul 27, 2015 10:43 am

Re: P51D Mustang

Postby deedubs » Thu Jan 28, 2016 8:26 pm

I got the rails from Mick Reeves models

paul f16
Posts: 50
Joined: Thu Sep 03, 2015 9:25 am

Re: P51D Mustang

Postby paul f16 » Fri Jan 29, 2016 1:08 pm

Ok cheers Dave.

I tested the U/C last night to make sure all was ok, it wasn't, the doors were operating fine but the gear did not operate, this really pi**ed me off as it was all set up and tested multiple times and then all connections sealed and final fit into wings, then it was all tested fine again. That was three weeks ago . The gear control modules were passing voltage on their correct switching times and the drives were clicking but not operating. I removed all the gear and put on the bench and operated the gear motor off of the lipo direct and its fine. Put it all back together on the bench including all extension cables and all is fine.
It appears that if the system has not been operated for a while the gear module will not handle the inrush of current on its first attempt and will not operate the gear.
To complicate things further the whole system has to be in sync , for instance the door and the gear have to be both in the same position to operate , so if the plane was airborne the first operation would be for the doors to open then after 8 secs gear to come down then 3secs later door to close , this being being known as the gear down position , and the reverse for up. But if the doors open and the gear does not come down and then the doors close again we are stuck with the doors in the gear down position but the gear actually still up even though it has received the signal to operate. Now in this position everything is out of sync, so you have to go through the programmer with each module and re sync the system.

Imagine getting to the flying field and setting up for this to happen.

So i have ordered an Xcoy electronic sequencer and I will do away with the modules :evil: :twisted:

RickTee
Posts: 49
Joined: Sun Aug 02, 2015 12:06 pm

Re: P51D Mustang

Postby RickTee » Sat Jan 30, 2016 6:29 am

Is this electric retracts? as I had noticed that with eflite retracts they have to be cycled once before they will operate, which would cause problems with sequencing.
Rick Tee

paul f16
Posts: 50
Joined: Thu Sep 03, 2015 9:25 am

Re: P51D Mustang

Postby paul f16 » Sat Jan 30, 2016 8:35 am

Hi Rick

Yes they are Electric made by a company called Lado . Normally Lado's stuff is good quaulity, but this is one of the firsts in their large size retracts and this set has not been in production very long so there is not many people i can ask questions.

As I said once their set up and in sequence they work great, but when not use for a while the gear drive wont operate on the first signal , i have had a volt meter in the connections at the gear drive and when its due to operate the 7.7volts arrives spot on and the motor gives the tiniest hint that its going to move but dont. So to me the module is switching ok but not delivering enough current to start the motor.

I have had a similar problem with 3 out of the 4 door motors ( electric rams ), to give you an idea how it works the ram looks like any small air ram and works on the principle of the section of shaft within the ram is threaded and when operated the internal section of the operating motor spins, this spin will either pull in or push out the shaft until it hits its stops , the stop is an O ring in a recess . This process giving the ram a soft stop . What we have to bear in mind that it is the over current device built into the tiny pcb in the top of the head of the ram which allows it to stop.

The problem I had was similar to what is happening now with the larger motors , it would work several times and then for no reason just click when it received its operating signal. What this turned out to be was that after several operations and the motors and stops etc bedded in the shaft would touch the inside of the ram case before the O ring compressed enough to stop the motor , in effect causing a hard stop , when the motor was required to work it could not overcome the required start current for the motor and would just click. This was easily solved by removing the shaft and taking about 1mm off the end of it. They have worked faultless ever since.

However the larger gear motors do not work in this way , they have extended threaded shafts which spin, these shafts then pass through a threaded collet which then either pushes or pulls the gear when operated. The stopping mechanism for this unit is when the collet locates into the locking positon for the gear locking the gear up or down. This works exactly the same as most air systems. So there is no soft stop within the ram it relies on locking the gear up or down to stop it. Now it appears that the in line programmable module is the same size as the door motor modules and i think they are too small and cannot handle the inrush of current at first start. Or is there something in the drive motor I am missing ?

When this kit arrives you get 4 X Door Rams and 4 X door modules and 2 X Mains U/C units with 2 X control modules , with this you get an electronic programming board. The idea being that you can use the board to programme each of the modules to control each of the motors to any sequence you require , you can then plug them all into one channel on your receiver and off you go.

There is one very small problem with this and it is it comes with NO INSTRUCTIONS !!!!!!!.

Can you imagine the frustration of A, figuring out how to programm the system, B, Understanding parts actually failing and not being a programme error, C, having to remove all the wiring and equipment from the wings when it fails , even after several tests.

Its lucky this system didnt have its first flight through the workshop window .

So having wasted considerable time on just this bit I have ordered a Xcoy electronic sequencer.

Cheers

Paul

paul f16
Posts: 50
Joined: Thu Sep 03, 2015 9:25 am

Re: P51D Mustang

Postby paul f16 » Sat Jan 30, 2016 8:44 am

Hi Rick

I forgot to add , I have already had one of the main U/C modules burn out !

paul f16
Posts: 50
Joined: Thu Sep 03, 2015 9:25 am

Re: P51D Mustang

Postby paul f16 » Sat Jan 30, 2016 1:23 pm

Just had a reply back from LADO , and it says yes you have identified the problem spot on it is a current issue and that they had the same issues and now run theirs through a power box or Smartfly unit. :twisted: :twisted: :twisted:

RickTee
Posts: 49
Joined: Sun Aug 02, 2015 12:06 pm

Re: P51D Mustang

Postby RickTee » Sat Jan 30, 2016 3:49 pm

Good news in one way, you have the solution, not so good having to fork out for something you shouldn't need or that should have been supplied. As for the one burning out, I'd be a bit concerned about why the current detection system didn't power it down before it got smoked. If that can happen on the bench ......
Rick Tee

paul f16
Posts: 50
Joined: Thu Sep 03, 2015 9:25 am

Re: P51D Mustang

Postby paul f16 » Sat Jan 30, 2016 6:50 pm

Hi Rick

With the new Xcoy sequencer , i will not be using any of the modules so that should eliminate that particular problem.

paul f16
Posts: 50
Joined: Thu Sep 03, 2015 9:25 am

Re: P51D Mustang

Postby paul f16 » Wed Apr 27, 2016 12:09 pm

Back on with the P51 now.

Finally got the engine starter ECU programmed correctly, working fine now.

Will sort the new retract sequencer tonight, then i can test run the engine.

Will take some more photos

dunney
Posts: 81
Joined: Mon Jul 27, 2015 10:49 am

Re: P51D Mustang

Postby dunney » Sun May 01, 2016 4:07 pm

More photos please. :)


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