Tracy Crook wrote:

 There are plenty of unused inputs on the EC2 which could be used for

knock

sensor input and the programming is reasonably straight forward.  All I

need

is the time to do it.  Won't happen this week (or this month) but it is

on

my list of things to do.

Tracy Crook
rws@altavista.net
www.rotaryaviation.com

Doug wrote:

I'm wondering if a guy could use a pressurized canister of alchol/water with
an electric valve that opens if a knock sensor detects detonation? In that
case one wouldn't have to carry a quantity for a constant supply or fear
water accumulation in oil or seals

I've been reading all the discussion of alcohol/water injection.  My 6.3 cents
worth.  It works fine for antidetonation protection, used by all the Reno
racers.  Both cools the intake charge (like an intercooler) and internally
prevents detonation.   No question about effectiveness, altho some of
the aftermarket auto systems may have been ripoffs that only put a
little water into an engine that really didn't HAVE to have it, unlike a
very highly boosted engine that will fail if it doesn't have it.

The primary (serious, IMHO) problem with the concept of using it as
a reactive detonation protection system is one of response time.  With
the OEM knock detection systems, the timing is instantly retarded when
knock is detected, like for the NEXT spark.   With any system spraying
water/alcohol, I would expect that the response time would be much
slower, and I am conerned that damage may occur before the ADI
(anti-detonation injection) system started to be effective.  The way ADI
has been successfully used is as a preventative, - turn it on as you
move into the high boost range, leave it on.  I think the reactive mode
is a risky application.  Might work, might not.  The way you'll know it
didn't work is when the engine comes apart.  OOPS.  Did anyone
say 'test pilot'?

I'd never use it except in racing or unusual TO (seaplane?) or emergency
wartime overboost situations - interesting that this is where it has been used
in the past. Good engineering (sometimes dissapointingly) usually comes
around to the same answers each time the question is asked.  Availability
of methanol is an issue.   What do you do when you are out of
methanol and on a cross country trip?  Or you are climbing on a hot
high and really need to clear that last ridgeline and the "OUT OF ADI
LIQUID" idiot light comes on?  Pull the power and hit the ridge?
Turn around and go home?  Stay in the throttle and blow the engine?
Clearly #2 is the only answer, but it is a pain in the rear, too.
I wouldn't use it for any normal transportation airplane, even tho it
technically works just fine.  By the way, methanol is a corrosive,
poisonous liquid that needs a little bit of special handling.  Seems
like it screws up paint, too - but that might be wrong.  I'm not
adventurous enough to use it.  NOx is a lot simpler, assuming the
engine is structurally up to the additionaly HP, as the rotary appears
to be.  Also tough to find on cross country trips, tho.

Bill
Long EZ builder & pilot
mechanical engineer

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