Matt, I've read your comments before on getting good bearing life and I've never understood why there is such a huge discrepancy. I'm really careful about not running the engine too lean, I run it as rich as I can without having it cough on mid range throttle-up.
I've also spoken to many others that have very short bearing life, indeed this is what prompted Brian to ask Boca to produce some SS bearings.
I would be very interested in pin-pointing why there is such a dramatic difference. Differences I can think of would include tuning (rich vs. lean), after-run procedures, fuel, climate, storage, and I've also heard that frequency of flying will affect bearing life.
Here's my parameters:
1. I run the engine as rich as possible while still having good throttle response in all ranges.
2. I always run dry and use after-run oil. I've used different ones, currently using about six drops of the oil from Magnum fuel. I've used more in the past but using too much pools in the head and kills glow plugs (more didn't seem to make a difference in bearing life anyways).
3. I run Magnum 10% or 15% depending on time of the year.
4. I'm in north Texas so climate is quite hot in the summers and often very humid.
5. I store the plane in my garage so it's exposed to heat/cold and humidity as the weather changes.
6. I normally fly a couple of times a week, many times only once a week, sometimes less frequently.
Keith Black
----- Original Message -----
From: Rcmaster199 at aol.com
To: discussion at nsrca.org
Sent: Sunday, September 26, 2004 8:59 PM
Subject: Re: Webra bearing life report
That is terrible bearing life from the set-up Keith. Mine lasted about 100 hours (452 flights) until the pump finally went, which meant the engine ran lean for several flights and then the bearing went.
Bearing no 2 has run all season and has about 32 hours on it so far, or about 150 flights; same engine with a new pump.
Fuel is the same cool power I spoke about before: 50:50 mix of 5% CP and 30% heli mix, plus one ounce of Klotz Pro per gallon
MattK
Prompted by Brian's excellent news regarding the new stainless steel bearings available for the Webra 1.45/1.60 I thought I'd share the following info on my Webra bearing life (standard non-stainless steel).
I keep a log of all flights including the duration of each flight (rounded to the minute). Last week I went through the arduous task of entering data on about 340 flights into MS Excel. I also keep a log of each bearing change so I was able to compile data on bearing life on over 70 hours of flight time.
All of my statistics below are reported in hours because flights differ in duration. Also, the decimal points represent a fraction of an hour, not minutes. For example 2.5 would be 2 1/2 hours.
I currently have three Webra engines, one in each of my two planes and one backup (thanks to the RadioSouth $259 special). I also had one Webra in which the bearings disintegrated and the engine was destroyed. Horizon replaced this engine free of charge (thanks Horizon). I have broken out bearing life times based on each engine.
Webra 1:
- Original Bearings: 12 hrs (may be off an hour or so, first runs were not in current aircraft and not logged)
- Bearing 2: 13.22 hrs
- Bearing 3: 9.40 hrs
- Bearing 4: still in engine, 0.67 hrs
Webra 2:
Original Bearings, 7.85 hrs (bearings disintegrated and destroyed engine)
Webra 3:
Originals Bearings: 11.38 hrs
Bearing 2: still being used, 6.37 hrs
Webra 4:
Originals Bearing 9.02 hrs
Bearing 2: still being used, 2.9 hrs.
As you can see the times for replacement vary between 7.85 hrs and 13.22 hrs. If you take out Webra #2 that suffered the early bearing disintegration then the range is consistently between 9 & 13 hrs. The average being 11 hrs.
I found this quite interesting as it represents a fairly consistent pattern of bearing life.
I'd be interested to hear anyone else's results or comments.
Keith Black
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