Today's Message Index:
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1. 01:10 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Gilles T)
2. 04:39 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Matthew S. Whiting)
3. 05:27 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Gilles T)
4. 05:47 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Matthew S. Whiting)
5. 07:59 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Gilles T)
6. 08:10 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Matthew S. Whiting)
7. 08:22 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Gilles T)
8. 08:39 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Alec Myers)
9. 09:00 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Gilles T)
10. 09:23 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Matthew S. Whiting)
11. 09:50 AM - Re: Simple sequencing using common 5-pin auto relays (user9253)
12. 10:09 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Matthew S. Whiting)
13. 10:32 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Gilles T)
14. 11:15 AM - Re: Re: Simple sequencing using common 5-pin auto relays (Matthew S. Whiting)
Message 1
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
Le 09/08/2023 03:13, user9253 a crit:
>
> You are right Matt. I did not read your original post carefully enough.
> You wrote, "mounting one as a toggle switch sideways that can be pulled towards
a guarded starter button. . . "
> I think that is the best solution instead of complicating the circuit with relays
or electronic timers.
> My 912ULS also requires 3 hands to start. One hand pulls the choke, one hand
turns the start key. It starts within 2 seconds.
> Then I have to push the choke in and lock it while simultaneously advancing the
throttle. It is not easy, but doable.
>
Hello all,
This conversation rang a bell.
In 2016-2017 I was asked to design the electrical architecture for a 912
IS installation in a light aircraft they intended to certify with EASA.
To avoid the multiplicity of switches I proposed the use of a rotating
key selector for the Rotax complicated start sequence, with a spring
loaded "starter engage" position. The electronic lane and pump test
switches were spring loaded to avoid any pilot error.
The start power was automatically disconnected as soon as bus power
exceeded ~13V, and is now managed by the single lever system.
This setup was accepted by the EASA certification team without any problem.
FWIW
--
Best regards
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
Le 09/08/2023 13:38, Matthew S. Whiting a crit:
> Hi Gilles,
>
> I understand the separate emergency power switch and am doing that
> also. I understand pumps and momentary start for starter engage.
> However what is the run position for? Does run activate the start
> power? If that is the case, what turns off the start power after
> engine start? Separate logic behind the scenes? Is this switch
> commercially available or proprietary to the company you worked with?
>
Hello Matt,
Out of memory - it's been 6-7 years - the idea was positions 2,3, 4
would have "start power" activated.
Pos 3 has pumps + Lanes activated.
So the "Run" position is pump + lanes and is the "normal" flight position.
Pos 4 activates the starter motor and energizes the correct pump as
specified by Rotax.
I had a British firm manufacture a couple of keyswitches as per my specs
in order to wire the prototype.
Yes a simple comparator circuit was designed to disconnect "start power"
once the engine alternator charges. In case of failure, Rotax assured me
that there was no drawback running an entire flight with "start power"
still connected.
Pump and lane test switch are momentary.
The idea was to avoid any pilot error or omission in the pump or lane
sequence.
Hope this helps
--
Best regards
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
Le 09/08/2023 14:46, Matthew S. Whiting a crit:
> /Gilles,/
> /
> /
> /Your design is very much like what I am trying to achieve in my home
> built, but with COTS parts and not having to build custom hardware. I
> am trying to essentially automate out the gymnastics that Rotax failed
> to engineer out of their engine start sequence. I am still amazed
> they havent done that as a computer controlled engine could easily
> drive the appropriate sequence and make starting a Rotax as simple as
> starting a car./
> /
> /
> /I have searched and not found an available switch like you describe
> which seems odd given the growing popularity of the Rotax engines./
>
Hi again, Matt,
No doubt the whole sequence can be automated with an Arduino or
something. Some factories already did that, but I personnally have some
preference for hard wiring and "human" sequencing when it comes to the
engine. And automation means electric power and not always obvious
failure modes and mitigation.
Having a modular keyswitch wired for a given sequence seems pretty
standard for some suppliers, and only cost a couple of dozen bucks, quid
or whatever ;-)
At the time Rotax IS builders were proud to advertize their neat rows of
several switches, cleverly located so you can pull one while pushing on
the other. Like other Diesel aero engines, like starting a locomotive.
A pilot error waiting to happen...
This is how they adapted the proposed principle, as viewed on a
production aircraft at Friedrichshafen
--
Best regards
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
Le 09/08/2023 17:09, Matthew S. Whiting a crit:
> /Well, when every firing of your spark plugs and fuel injectors is
> running off a computer, I am not too worried about the computer
> controlling a couple of simple functions at engine start. :)/
>
As long as your chips are as robust, redundant and proved as theirs and
you performed the same amount of tests and failure mode analyses ;-)
--
Best regards
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
This is prime territory for an 8-bit PIC microcontroller. Code that is only 30
lines long is easy to test, and the hardware already exists in the billions.
On Aug 9, 2023, at 11:22, Gilles T <gilles.thesee@free.fr> wrote:
Le 09/08/2023 17:09, Matthew S. Whiting a crit :
> Well, when every firing of your spark plugs and fuel injectors is running off
a computer, I am not too worried about the computer controlling a couple of simple
functions at engine start. :)
As long as your chips are as robust, redundant and proved as theirs and you performed
the same amount of tests and failure mode analyses ;-)
--
Best regards
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
Le 09/08/2023 17:38, Alec Myers a crit:
>
> This is prime territory for an 8-bit PIC microcontroller. Code that is only 30
lines long is easy to test, and the hardware already exists in the billions.
>
>
Some ultralight manufacturer did that and was approved by EASA.
That said, after chatting with the designer at Fried 2018 I didn't get a
clear idea of what was doing what in the sequence.
Maybe old fashioned pilot preferences, a bit like having a
microcontroller managing the trims during flaps maneuvering when trim
forces are light, or having electric flaps when manual would do the
same, etc.
For instance my digitally regulated soldering iron is a pain to adjust
and loses settings, when I could have ordered the manual potentiometer
version doing the same, just quicker ;-)
I'm not against electricity and automation as a means to an end, but I
hate wondering "what's it doing now?"
That said I'd be much interested in having details on Matt's final
realization.
--
Best regards
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
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| Subject: | Re: Simple sequencing using common 5-pin auto relays |
How about this circuit? I am not necessarily recommending it, but I think that
it does what you want.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=511233#511233
Attachments:
http://forums.matronics.com//files/rotax_start_relay_102.png
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| Subject: | Re: Simple sequencing using common 5-pin auto relays |
That is nearly what I have now. The main difference is the diode connection to
the start power is replaced by the delay relay. I it will be fun to experiment
when my battery box gets back from the fabricator and I can start putting things
together.
Sent from my iPad
> On Aug 9, 2023, at 12:52 PM, user9253 <fransew@gmail.com> wrote:
>
>
> How about this circuit? I am not necessarily recommending it, but I think that
it does what you want.
>
> --------
> Joe Gores
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=511233#511233
>
>
>
>
> Attachments:
>
> http://forums.matronics.com//files/rotax_start_relay_102.png
>
>
>
>
>
>
Message 13
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
Le 09/08/2023 18:22, Matthew S. Whiting a crit:
> /I agree that a small microcontroller would be a decent solution,
> however, my coding skills are more than a decade rusty and it would
> take me far more time to get up to speed again than it is worth. And
> the reality is that the system would likely not be maintainable down
> the road./
> /
> /
> /I am going with a momentary switch and push button starter with
> separate switches for the lanes and fuel pumps. On paper, it seems
> like my three relay and one diode solution will work and this will
> allow me to use the momentary toggle switch to latch the relay holding
> start power until the starter is engaged. The starter relay will then
> take over the provision of start power as well as engaging the
> starter. Once the starter push button is released, the start power
> should also release./
> /
> /
> /If this works great, if not, I will simply hold the momentary toggle
> while pushing the starter button and plan to mount them close together
> so that one hand can hopefully actuate both. This is my fall back
> solution./
IIRC, "start power" is for powering the electronic lanes and pumps until
the engine alternator takes over. In my experience it took some time
until the engine was "autonomous".
I would advise to try and make it physically impossible for a pilot to
take off with the pump or lane switches in the wrong position.
It happened to a buddy pilot who sometimes visits here, with the 914
infamous two-pump fuel system.
BTW it occurs to me that I might have provided some background to the
choices I mentioned.
The goal of the design team was certification of their project - which
they finally obtained - and in my experience certifying means convincing
"your" system or structure expert that he won't be sued should something
happen with your setup after he approves it.
So sitting with him I had to demonstrate how things wouldn't go hairy if
my little "Start power" device failed.
Fail to close => engine won't start.No crash.
Fail to open => no incidence on engine as guaranteed by Rotax. Safe
continuation to destination.
On the other hand the engine/instruments "expert" didn't allow the cute
little digital backup instruments my partners liked and they had to
resort to classic steam gauges.
And the clever optical low level fuel sensor had to give way to a
mechanical switch and idiot light due to the requirement to analyse the
3rd party device and 5V power supply.
Of course the above are constraints a homebuilder or ultralight
manufacturer isn't subject to.
FWIW
--
Best regards
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
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| Subject: | Re: Simple sequencing using common 5-pin auto |
relays
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