Lycoming AEIO-390X with MT Propeller
Andre van Rensburg
When it came to fitting an engine I chose the Lycoming AEIO-390X
engine from BPA instead of the standard AEIO-360 engine. The IO390
engine has a counter weighted crank and the difference in flight is
quite significant. During the test flights I felt no vibration and in
theory I should not have the limitting RPM range Eagles normally have.
Apologies to Allen Barret for not mentioning his help in my previous
post - thanks for a great engine Allen.
The MT propeller has turned out be be great so far and I can't tell if
it is may imagine, but I seem to have a bit more than the 210 hp
adverised by Lycoming. The MT prop was made 2 inches longer than the
standard Eagle prop (on recommendation by MT) and this may be
contributing to the extra power I feel. Thank you MT team in Germany.
I also fitted a 4 in 1 exhaust from Sky Dynamics which I believe
should give 5% more power.
Anyhow, I can highly recommend the IO390X and MT prop combination to
anyone out there looking for a power plant on their Christen Eagle.
Andre
Eagle N23TS
Could you reply with a bit more detail please. What MT Prop
(exactly)? How much time do you have on the prop and engine combo and
what are you comparing it too (I speculate a 2 blade Hartzell)? Do
you have any data to support your claim (speed, climb, drag, vertical
penetration)? Was your prop balanced (both old and new). Wood vs
metal is quite a change in dampening of vibration. Did you fly both
props on the same engine and actually compare performance data? There
is no way the wood prop can outperform the two blade metal prop and
use the same horse power. It simply is not possible according to MT
and physics (and anyone who has used both like myself). Metal blades
are stiffer and thinner (i.e. 10-30% more efficient). Do you have a
fuel flow meter? Can you see a change in fuel flow? How much?
My MT 3 blade used more fuel by 4 gph in climb and 2 gph in cruse,
less climb rate by 300 fpm, only 800 feet of vertical penetration from
level flight to vertical w/ a 3g smooth pull. Lower cruse speed by 12
knots (i.e. less efficiency and performance for the same fuel burn).
Torque rolls went from two full roles to hardly one. I can't forget
the no wind milling problem with any light weight wood prop. More
specifically, in a 45 degree dive the prop will not turn over at all
(MT 3 blade at 45 degrees nose low is 85 mph dead stick and 12 seconds
from 1000 AGL to wheels down). In short, you loose the engine and you
are reliant on the starter to turn the prop in flight for a restart.
30 lbs of weigh removed from the nose caused a major change in the W&B
to a dangerous level. Lets not forget the 4" CG range of the eagle...
The 3 blade had two improvements, vibration went down significantly
and aerodynamic braking action was impressive. Formation flying is
pathetically easy with the braking action of the MT prop. I liked the
appearance better too... Other than that, I and others can't see any
reason to change props (except for crankshaft concerns). Your
operating limitations must change to be legal to fly and more
importantly be covered by insurance. I bet you forgot that... ...I did.
However, if gentleman aerobatics are the only flying one does,
changing the prop from metal two blade to MT 3 blade is an expensive
loss in performance and CG change. If you have your old prop and
spinner, and it is in good condition, I want it...
The RPM limitation on an eagle has nothing to do with the engine, it
is purely a Hartzell prop limitation... (reference your manual, AD's
and Aviat). Your engine is safe to 3100 RPM stock. Not recommended,
but quite capable (reference Lycoming tech documents). Reno racers
use stock engines and light wood props to turn 3100-3200 rpm.
No stock eagle puts out more than 130-165 horse power. You can
measure your engine horse power with a radar gun and stop watch
(assuming you know the real weight of the plane). Weigh the plane
(include yourself) and time the acceleration from 0 to any speed you
want (you don't have to take off). Do the basic math of acceleration
of a mass vs. time/speed to determine Dead nuts on actual horsepower
(minus the small tire friction factor)! Radar guns are 9v battery
powered and only $300 on line.
Scales are at your FBO and you probably need an actual and current W&B
anyway. Don't forget to add fuel after the empty weigh in and
determine your actual fuel capacity (mine is 28.5 gallons)...
If buying a radar gun is too much for you, just do the hypothetical
math on a spreadsheet and change the constants and unknowns. You may
find the acceleration being constant, 200 HP constant, that the weight
of the plane has to be 450 lbs...
Brock
N23TS
On Feb 22, 12:05 am, "Andre van Rensburg" <andrevanrensb...@yahoo.com>
wrote:
Andre van Rensburg
I am using a MTV15B-C/C193 (2 bladed propeller) that b.t.w. goes fully
coarse in case of loss in oil pressure /engine failure.
As you mentioned the MT is about 25 lbs lighter than the Hartzell, but
the IO-390 engine is 8 lbs heavier and by using a light-weight sealed
battery I managed to get the empty weight and CG at 1058 lbs and 89.04
inches.
I am not really one for getting into scientific research on aircraft
so I won't be able to supply you with all the figures you want, but
the MT and IO-390 combination is great - believe me !!
Andre