Hi Mike,
Was not trying to get you to change your
wiring, just providing my viewpoint on my preference. As I said - having
the switches brings some down side such as possible component failure
(switches), miswiring causing trouble shooting and head scratching, etc.
Yes, I once had an injector fail to open
(turned out to have developed an open coil) in flight – at the time
of flight was not certain what the problem was but found that by switching off
the affected pair made the engine run smoother and EGT even out. Could
undoubtedly have made it home without doing that in this case, but it was nice
to isolate the problem and come home with a smooth running engine.
Early on I discovered that some of the
injectors I was trying out on the ground – were bad (coil OK with Ohm
meter check) but just wouldn’t inject fuel, the switches make it much
easier to isolate which pair and then which injector was the bad 0ne. If
you don’t have a bunch of old injectors to check then this does provide
any benefit.
Yes, you can always pull the electrical
connector on the injectors, but with my primary injectors in the block behind
my intake manifold – it is not an easy job. Switches make it
easier.
No fuses, but I do have Circuit Breakers
in those lines, so you are correct - a shorted wire should cause no ultimate
problem that the popping circuit breaker wouldn’t take care of.
Agree, you can kill the engine any number
of ways. However, early on the EC2 had a sneak circuit that provided
sufficient power through the injector power wires to the old EC2 (long ago
corrected) to continue to power it. So you can imagine my surprise after
I first installed the EC2 and turn off the power to it a (but not the injectors)
– the engine continued to run. So not knowing what was going on , I
killed the engine using my injector switches and found I like the way that
brought the engine to an immediate stop.
Yes, you can turn off the fuel pump but
there is still pressurized fuel in there for a moment or two that can continue
to inject into your engine until the pressure drops down. You can turn of
the ignition and ditto. Again no biggie, but I like the way the engine
stops when the injectors are turned off – there is No wind down, the
engine stops producing power immediately.
Again, was as not trying to get you to
change your wiring, just providing my viewpoint on my preference .
Ed
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Mike Wills
Sent: Tuesday, March 16, 2010
10:22 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Injector
Select Switch [FlyRotary] Re: Civil Discourse was : [FlyRotary] Re: Ut-Oh...
1) Have you ever had an injector failure that required
this?
2) There were a number of occasions during initial debug
when it was helpful to disable injector pairs. It was easy enough to do this by
pulling power where they were plugged into the essential bus. Not as convenient
as flipping a switch, but I don’t anticipate having to mess with it ever
again.
3) Are your supply lines to your injectors fused? If
not, why not? If they do short in flight how do you know to turn off the
switches?
4) I turn off the fuel pump to kill the engine. I suppose
this does leave a possibility of a little fuel in the chamber? Not sure there
is any reason for concern?
Sent: Tuesday,
March 16, 2010 6:30 AM
Subject:
[FlyRotary] Injector Select Switch [FlyRotary] Re: Civil Discourse was :
[FlyRotary] Re: Ut-Oh...
I also find the “Injector
Select” switches useful for several purposes, Rino.
1. If a problem with one injector of
a pair occurs, I can turn that pair off and fly home on the remaining pair.
2. They are great for trouble
shooting injector problems by permitting you to choose which pair will be on
without question.
3. In the highly unlikely (but possible)
event that a power wire to a pair should short to ground, you can turn the
power off to that pair.
4. I also use them to turn off the engine
– that ensures no residue fuel in the housings.
But, if not wired correctly they can
cause a new installation some puzzling problems {:>) and they do add another
component and we know components can fail – although if sized properly
for the correct current and installing quality switches and wire correct the
failure in one will not take you down and the likelihood of both failing at the
same time is rather remote.
But, once again, you can certainly fly
without them – I just find them very useful.
My 0.02
Ed
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Rino
Sent: Tuesday, March 16, 2010 8:05
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Civil
Discourse was : [FlyRotary] Re: Ut-Oh...
I find the "injector failure Switches"
convenient during the warmup to test the operation of the injectors just like
the primary and seconday plugs test.
----- Original Message -----
Sent: Tuesday, March 16, 2010 1:23 AM
Subject: [FlyRotary] Re: Civil Discourse was : [FlyRotary] Re: Ut-Oh...
I chose not to
implement the "injector failure switches". I don’t know if
there are any statistics on it, but I suspect injector failure is an extremely
rare occurrence. On the other hand if one did fail I'd rather fly the
plane and troubleshoot the problem after I'm on the ground. But that’s
part of the advantage in going the Experimental route - build it the way you
want it.
Sent: Monday, March 15, 2010
8:47 AM
Subject:
[FlyRotary] Re: Civil Discourse was : [FlyRotary] Re: Ut-Oh...
In the event of a
primary or secondary injector failure, the affected injector set can be
switched off and the cold start switch used to richen up the remaining
injectors. This as per Tracy's
instructions. I haven't tried this, and hope I never have to in the heat of
battle, but there it is.
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