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Mark;
Good point on the fuel cost. Here’s
another that is fresh in my mind. I noticed a few weeks that the voltage was
fluctuating during flight, ranging about 1 ˝ volts, and hitting a high over
15.5 volts. I use the internal regulator, but modified to use external field
supply with a ‘crowbar’ circuit for over-voltage protection. I decided
to replace the regulator. Took the alternator off, opened it up, got a
replacement regulator at a local rebuild shop for $38; back together on the
plane, working fine. Meanwhile my friends Bonanza is in for an annual. They
decided the alternator wasn’t putting out what it should –
replacement cost: over $700.
His Continental (520 I think) is past
the 1750 recommended TBO. So he is debating between factory reman at about
$35,000, or new at about $45,000.
Yeah; I love my rotary 20B.
Al G
-----Original Message-----
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Mark Steitle
Sent: Tuesday, March 03, 2009 5:24
AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Questions
on buying a rotary plane
I'll throw my 2 cents worth in here.
Regardinging fuel burn, I'm not overly concerned with bsfc, although its not
that bad if you're running EFI. What we're really interested in is cost
per mile. I have burned nothing but mogas in my 3-rotor Lancair.
The last time I purchased fuel, it was $1.65/gallon. My N/A
3-rotor burns between 10 and 11 gph at around 20" MAP. So, it
will cost me somewhere around $16.50 - $18.15/hr to fly. Other
Lancair ES's are running IO-540's, or some derivative of the
"540". From what I hear, they burn between 12 - 15 gph.
With the cost of 100LL running around $4/gallon, that would cost between $48
- $60/hr in fuel. So, figuring cost per mile, I don't see how a
Lycoming could come close to matching a rotary. The fuel savings
alone will more than cover the cost of an overhaul.
And hope the Lycoming doesn't burn a valve, or
any number of other common ailments which can take a serious bite out
of your checkbook. Most of the things that break on a piston engine
aren't even present on the rotary. If it ain't there, it can't break.
So, would I use a rotary if I were to do it over, yes,
absolutely!
On Mon, Mar 2, 2009 at 11:31 PM, William Wilson <fluffysheap@gmail.com> wrote:
I have
not found an accomodating A&P but I attribute that to the fact that I have
not looked yet. Given that I live in Seattle I am pretty sure I can find
one. Seattle is crawling (fluttering?) with homebuilt planes. If
anyone has suggestions, I am listening, but I had not started searching yet.
Plan is not to take apart a perfectly good flying plane to change the engine,
but ideally to get one with a rotary in it already, or replace only at overhaul
time. In each case I save as much on the cheaper engine as I would lose
on resale value... and if the plane has the rotary in it to start with, I get
to pay the lower price up front too, which makes price difference just plain
better.
For efficiency what I said was that homebuilt planes are more efficient than
factory built, not that rotary are more efficient than Lycoming, though in that
case it should be quite close. Bad fuel economy of rotary engine is
overstated, economy is comparatively bad at low power & RPM but at high
power it is not bad at all. As long as you are not turbocharged, you can
run much leaner than a piston engine, making up for less efficient combustion
chamber shape. Rotary BSFC in the lab has gone as low as .375 (for
renesis), and .44-.46 measured in real world racing applications even with
traditional type engine. So I think I would not see a significant
difference in fuel economy between rotary and piston. Weight & drag
of the plane it is in will matter more.
In any case all advice is welcome, even dissenting opinions ;)
I highly recommend you check
around to make sure you can find an A&P who will do a condition inspection
with the rotary engine installed BEFORE you commit. Many A&Ps I've talked
to dont want anything to do with Experimentals let alone an engine that looks
nothing like what they are used to. There's simply too much potential liability
(real or perceived) to go out on a limb like that. The A&P who used to do
the condition inspection on the RV-6A I used to own (Lycoming powered) was
willing to do it because the RV structure is similar to typical spam cans. He
wont have anything to do with wet layup homebuilts (EZs, Cozys, etc...). He
doesnt even like doing annuals on Diamond aircraft with the Rotax 912/914 and
they are certified.
If you buy a flying homebuilt
that is Lyc or Continental powered, before you convert it to rotary power
seriously think about what you are doing to the resale value - if you could
ever sell it that is. My guess is that you'll give up at least $10,000 in
resale value, maybe much more. No big deal if you plan on keeping it for life.
I dont know where you got the
idea that rotaries are more fuel efficient. Lycosaurs/Continentals typically
have BSFCs in the low .40s. The commonly accepted number for a rotary is about
.50. Some here seem to do better, others worse. With a grand total of 2 hours
on my rotary I cant say what my experience will be but hope its close to the
Lyc I used to fly.
Finally dont underestimate the
effort required to make the change. I started building my RV-4 in late
1995. The airframe was essentially done in 2000. My first flight was last
month. Granted I took longer than many and much of the trouble came from my
desire to eliminate the cowl cheeks on an already cramped engine compartment.
But thats eight years of tinkering to get the engine installed and running to
the point where I had enough confidence in it to fly it.
Not trying to discourage you,
but go into this with eyes wide open.
----- Original Message -----
Sent: Sunday,
March 01, 2009 7:46 PM
Subject: [Norton
AntiSpam] [FlyRotary] Re: Questions on buying a rotary plane
This
is great news. Thanks Charlie and Bob :)
On Sun, Mar 1, 2009 at 7:34 PM, Charlie England <ceengland@bellsouth.net>
wrote:
William Wilson wrote:
I am in the market for a plane and would prefer a
rotary-powered, as I have lots of experience working with rotary engines.
As a bonus, homebuilt planes all seem to get about twice as much fuel
economy as factory built planes. So that is nice too. I know there
are a few rotary powered planes available for sale, but not too many.
I have neither the time nor desire to build my own plane, so my question is
more about maintenance and inspections. I'm not an official A&P and I
don't know if I will be able to find an A&P to work on a home built plane
with a car engine in it! I am happy to do engine maintenance, but am not
entirely clear on the legality of it, since I would not be the original
builder.
Similarly when it is eventually time for an engine rebuild, would I be able to
remove the engine, take it down to Atkins (who are not far from me) and have
them rebuild it, or rebuild it myself, and then reinstall it, and find an
A&P to just sign off on the work?
Plan B is to buy whatever plane even if it has a Lycosaurus, but when time for
overhaul comes, get rid of the Lycoming and replace it with a rotary.
Thought in this case is to get the rotary tuned, a little broken in and
running on a stand in the hangar in advance, so that when the time comes to do
the swap it can be done with a minimum of downtime. (I know it cannot
really be tuned for altitude in this way but it is better than nothing!).
But again, the fact that I would not be the original builder makes me
worry about legalities. I have heard that this has been done so question
is more about the how.
I do not really understand all the law involved and hopefully somebody here can
help. Thanks!
I can't speak with authority, but I can speak from
experience.
Experimental homebuilts can be maintained or modified by anyone. No FAA
blessings required. Annual condition inspections must be performed by either
the holder of the 'repairman's certificate' (only available to the builder of
record) or by the holder of an A&P ticket (no IA required).
Once the airworthiness certificate is awarded, *anyone* can do any maintenance,
repairs, modifications etc desired. The post-modification requirements vary
somewhat from plane to plane depending on when the a/w was issued, but in
general terms, you notify the FAA in writing that major mods were made, ask for
a defined test area, make a log entry detailing the return to 'phase one'
testing, fly test flights for (typically) 5 hours, then make another log entry
saying that the plane has been tested with the mods & is being returned to
'phase two' (normal operational) status.
'Major modification' isn't clearly defined, but if you have to ask, it's major.
:-)
The availability of an A&P to sign off condition inspections is all over
the map (literally). It's never been a problem for me, but in some parts of the
country people can't find an A&P who will sign off *any* homebuilt,
no matter what engine. If you have that problem, get to know the guys who
sign off the crop dusters in your area.
Hope that helps....
Charlie
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