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----- Original Message -----
From: "Marvin Kaye" <marv@lancaironline.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, March 25, 2003 8:45 AM
Subject: [FlyRotary] Re: Spark Plugs
> Posted for "Ian Beadle" <ianb@ozzienet.net>:
>
> Hi Ed
> Did you try the B9EV plugs? 10 hrs! what do you use for fuel? Nitro?
Are
> the BUR plugs surface gap? If so after 'plug sag' (sounds like a new
disease)
> get a 500volt megger and check if you have conductive lead on the
insulator.
> How's the fuel flow gadget coming along?
> Have a beer for me.
>
> Ian.
>
Hi Ian,
No, have not tried the B9EV plugs yet. I used the BURs which are not
surface gap but have four grounding electrodes straps around the center
electrode. The SAG shows up as an approx 300 deg F drop in the affected
rotor EGT. Also, the rpm may drop around 100-150 rpm (if only one chamber
has the SAG, may drop up to 300 rpm if both). It mainly appears to happen
at high power settings. I used 100LL and get approx 25-30 hours on the
plugs before SAG starts to appear. It initally only happens maybe once or
twice per flight, but occurences increase rapidly afterwards. Tracy uses
same plugs and gets approx 100 hours using No-lead auto fuel.
I suspect that the ceramic surrrounding the center electrode gets fouled
(covered with lead) which bleeds off some of the spark energy before it can
build to jump the gap. The electrodes are hardly worn and I intend to take
some of the SAG plugs and use a sparkplug cleaner and see if that helps any.
Been side tracked from finishing the microcomputer version, decided that
assembly language was just too hard and decided to go to a higher languague
like "C". Then found that the microcomputers won't accommodate a normal "C"
compiler and you need a special one. Order one and then found out it was
buggy as hell, didn't need a buggy compiler while trying to learn "C".
Think that was about solved when my Ross PSRU showed galled gears on annual
inspection, so decided to go with Tracy Crooks better designed drive. Took
about a month to get the rotofit all done. Now, getting ready for Sun &
Fun. So hopefully, I can get back on the design after Sun & Fun and get at
least the first version done. Never thought it would take this long. Still
flying with my analogy version which continues to work just fine.
Looks like you are getting a lot of flying in. How, many hours on the
airframe to date?
Best Regards
Ed
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