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<< Lancair Builders' Mail List >>
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Gentlemen
Lets see if we can put this subject to rest. The relationship between max
range and max endurance is given by:
Speed for Best Range=Speed for Max L/D
Speed for Longest Endurance= Speed for Max L/D Divided by 1.316
We can also discuss the optimal cruise speed, which results in the minimum
fuel flow per knot of airspeed. This is given by
VmaxL/D*1.316.
These equations assume no wind, and a fuel burn rate that is proportional
to power delivered. (constant efficiency). For details, see
http://www.eaa1000.av.org/technicl/perfspds/perfspds.htm
To address Steve Reeves questions relating to the 235, as a happy owner of
one of these birds, I will provide my two cents...
The 235 kit was not produced in as great a number at the 320/360
variation, and you certainly don't see as many 235's around anymore. As
far as the tradeoffs between the 235 and 320/360, I offer the following
observations:
The 235 represents a good tradeoff between economy (purchase and operat
ing) and performance, but has some limitations that should be considered
before deciding on one. As far as cost, 235's, when you can find them,
sell for between 40 and 60 k. The 320's and 360's are about twice that
amount.
With the standard 118 HP 0-235 powerplant and fixed pitch prop, takeoff
and climb performance is "modest", and may be a limiting factor when
operating at high density altitudes. My plane has the L2C engine with
9.7:1 pistons. I comfortably operate out of a 2600 foot paved runway at
sea level. I see climb rates (full fuel 33 gal) of 800 fpm solo, and 600
fpm with a passenger at 120 mph. I am reluctant to operate out of high
altitude airports unless solo. I visited Lakeview, Oregon this summer,
which is around 5000 MSL. The 5000 foot runway was more than adequate for
the early morning departure (solo). Takeoff and climb performance should
be improved greatly if a controllable pitch prop is used. (I see 2370 RPM
static)
Cruise performance is 190 mph indicated at 25 inches and 2650 rpm, 3000
MSL. Fuel burn is typically between 6.0 and 7.5 gph in cruise. True
speeds of 200 mph at 21 inches and 2700 are achieved at 9000 feet. My
empty weight is 945 lbs. Don't expect to carry much baggage with full fuel
and a passenger. The 235 airframe is only slightly smaller than the newer
320/360, but the instrument panel is considerably smaller, and outfitting
for full IFR was a challenge. My panel has a single COM, Transponder,
VM1000, Airspeed, Horizon, Altimeter, Turn Coord, Loc/GS, Marker Beacon,
Vac, Gyro Compass, and Climb, Carb Temp, Clock and fuel gauges. I cant get
anything else in! I am presently not IFR rated but plan to start soon.
I haven't flown a 320/360, but the stability and sensitivity of the 235
(IMHO) makes it less than an ideal IFR platform, The aircraft is neutral
in roll, and requires attention to keep the wings level. A single axis
autopilot should be considered for IFR. Pitch control is very light. My
aircraft does not have a bob-weight on the elevator linkage, and I've been
told that this would help.
The above performance figures are observed values from my aircraft. There
are many 235 airframes with O-290's or O-320's in them, and the will
obviously have better performance. Many recommend installing a larger tail
when using the larger powerplants. Hope this helps.
All in all, I think the 235 is a great little plane, and was still the
best choice for me. I wish that Lancair would introduce a new kitplane
that fills the niche that the 235 had once filled. The Legacy is a very
nice airplane, with more power, performance, payload, and room than its
predecessors. It is however a very expensive airplane. If Lancair
produced a kit for a 235 class airplane for $35K using some of the Legacy
quickbuild construction techniques, and employing the 160 lb. Jabiru 120 HP
engine (around $10K new), you could probably finish such a plane for around
60k. It seem with the emphasis on faster, higher and larger, that Lancair
has conceded the affordable sport plane market to Rans. If not for the
235, based on cost considerations, I would have probably ended up with an
RV 6 instead.
Tom Low
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LML website: http://www.olsusa.com/mkaye/maillist.html
LML Builders' Bookstore: http://www.buildersbooks.com/lancair
Please send your photos and drawings to marvkaye@olsusa.com.
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