Subject:=20 [FlyRotary] Re: Engine failures, Rotary or otherwise

To=20 clarify the air filter issue. I seem to remember someone posting a = page from=20 the mazda manual regarding apex seal tolerances after Ed's = failure and=20 later confirmed the slot was out of spec. I remember the manual said = to check=20 the air filter. Mazda seems to think running without a filter or = (dirty=20 filter?) will cause rotor apex seal slots wear. Is this=20 correct?

Bobby

I don=92t = think there=20 is any doubt that every =91terrestrial=92 vehicle needs an air filter. = They=20 run on dust laden surfaces, and, at times, on unpaved surfaces which=20 themselves are dust; resulting in the ingestion of a lot of abrasive=20 material.

The = rational (at=20 least mine) for not using a filter on an aircraft is that, a) it = spends little=20 of its time on a surface, and then on one that is paved a periodically = blown=20 off by other aircraft, and b) the amount of particulates above a few = hundred=20 feet (and certainly at a few thousand feet) is very low; probably = similar to=20 what goes through a filter in dusty conditions.

If my = flights=20 averaged something like a couple of hours each, there is about 15 = minutes on a=20 relatively clean surface for every 2 hours up in clean air. If = the rpm=20 in the air is 5500 and that on the surface is 1800, then the fraction = of air=20 volume used where there may be some fine particulates of concern is = about=20 4%.

So I=92m = willing to=20 accept that in exchange for keeping the ram air manifold pressure = increase of=20 about 1.5=94 Hg that I can get when cruising close to 200 mph for the = 2 hours=20 that I=92m not on the surface. A compact filter is going to eat = most if=20 not all that ram pressure. If you aren=92t concerned about the = pressure=20 loss, or you can include a sufficiently large filter enclosure, and = not lose=20 too much of the ram pressure in expansion, contraction and friction = losses;=20 then it makes sense to include an air filter.

I am = definitely not=20 advocating not using a filter. Just giving you my rational, = however=20 faulted, for going without one. (BTW, I do have a screen at the = largest=20 diameter in the intake duct to prevent anything bigger than about = 1/32=94 from=20 getting through).

FWIW,

With=20 all due respect; I don=92t disagree with what you=92re saying here, = but I do take=20 offense at you calling Tracy, myself, and others =93idiots=94 because = we have=20 chosen to run without an air filter. My intake is in front of = the prop=20 and above the wing strake. Anyway, why climb on that = issue? There=20 has not been a single aircraft incident that I am aware of that has = resulted=20 from not using an air filter. Let=92s pick an issue which = has=20 caused a failure.

I=20 won=92t argue that running without a filter may reduce the engine = life; and I=20 may consider one later. And yes, the engine would eventually = fail; every=20 engine will =96 filter or no filter - if you run it long=20 enough.

Al (I=20 guess it=92s past my bedtime)

Rusty,=20 and Group,

I=20 understand your comments Rusty, and think you are both right and = wrong. I=20 believe it is easier, for most people, to be successful with a = standard=20 aircraft engine. I DO NOT believe this is because the Lyc, Conti, or = whatever=20 is inherently more reliable. I do believe that the ancillaries are = better=20 developed for "conventional" aircraft engines. =

Because=20 we [FlyRotary or ACRE] are = rotary=20 enthusiasts we hear about EVERY rotary problem. If we heard about = every Lyc=20 problem caused on a daily basis we might never fly spam again! I am = not trying=20 to offer so anecdote to soothe the rotary faithful, as all failures = are just=20 that, failures. I would remind everyone that ALL Lyc installs in = certified=20 aircraft now come with AIR FILTERS!

I'LL=20 SAY THIS FLAT OUT, IF YOU DON'T RUN A FILTER YOU WILL HAVE A FAILURE! = I don't=20 care if your running a conventional aircraft engine or conversion. = Running=20 unfiltered is simple idiocy.

It=20 should also be said that for Lycoming to be having crankshaft = failures, and a=20 significant number of them to initiate an AD is not only sad but = smacks=20 of reckless disregard. So saying that the aircooled aircraft engine is = super=20 reliable is simply setting yourself up for a fall. If you look at the=20 statistics most of the engine failures are "certified" engines simply = because=20 there are more of them!

ANY=20 ENGINE properly maintained and not operated outside it's normal limits = will=20 work just fine thank you, provided it is not a deficient design to = begin with.=20 The rotary requires a GOOD water and oil cooling system. If you aren't = willing=20 to work on that, stop now and don't hurt the reputation of the rest of = us and=20 go buy a Lycoming. The rewards for a GOOD installation are many but = won't=20 "just happen." As Tracy said you = must go in=20 with the knowledge of the needed systems or you will fail. If you do = slipshod=20 work, Rotary or Lycoming, YOU WILL FAIL. Someone put the old saying on = the=20 site, "How do you eat an elephant?" "One bite at a time!" This is the = proper=20 way of looking at the jobs needed to be successful. You MUST do all = the jobs.=20 (eat every bite) And most importantly you must do all the jobs well. = Safety=20 wire everything even though it's a pain in the ass. If you can't do = all the=20 jobs yourself it's no crime. Get HELP! Buy the redrive from=20 Tracy. Or buy = from=20 Mistral, or buy them from Marcotte. Build your system up and test it = on the=20 ground. If you overheat your system on the ground don't assume it will = be=20 better in the air! (It might be, but also might not be!) Plan for an = adequate=20 sized radiator. That would be a MINIMUM of 2 cubic inches pre HP, and = that=20 only if you have PERFECT ducting. (3 c.i. per HP would be a safer bet) = Don't=20 expect you are the miracle guy that can change physics for your own=20 project. Rusty has brought up some good points in pointing out = that if=20 you want to fly soonest buy conventional. Bernie, you can probably = rebuild=20 your system from all new parts for less than the cost of two Lyc = cylinders. As=20 an older guy facing family pressures I can understand how you might = not want=20 to though. This is no crime. Your needs are your own, though I would = prefer to=20 see you go back to the rotary and succeed. We all need to go in with = our eyes=20 open. When setting up race cars and motorcycles I would look at every = part=20 from the stand point what will happen if this part breaks? If the = result would=20 be a crash I would redesign the part until I was SURE it wouldn't = break. If=20 you don't think a part is adequate DON'T USE IT! Your responsibility = is to=20 find a part that IS good enough. Don't just hope that everything will = be OK.=20 Work it out. Run your system enough to be sure of it in the=20 air. I hope everyone takes this in the spirit intended which = is to=20 have us all come home safe.

Bill=20 Jepson