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hurlbut(at)ns.sympatico.c
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 Posted: Sat Nov 10, 2007 9:45 pm Post subject: Propeller for sale |
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MT Prop model MTV-15B/183-50. 136.5 hours flight time since new. No damage ever. Log books included.
Manufactured June 2006.
Removed from RV7A IO-360 for flight testing other props.
Email for pics.
$8000 OBO
Steve
RV7A
[quote][b]
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aerobubba(at)earthlink.ne
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| Posted: Sun Nov 11, 2007 8:55 am Post subject: Propeller for sale |
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Hi Steve-
I've got a prop, but what was the outcome of the testing, aside from
selling the MT? Enquiring minds want to know!
| Quote: | Removed from RV7A IO-360 for flight testing other props.
Steve
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glen matejcek
aerobubba(at)earthlink.net
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hurlbut(at)ns.sympatico.c
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| Posted: Mon Nov 12, 2007 4:37 am Post subject: Propeller for sale |
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For those who inquired:.
MT PROP IS STILL FOR SALE. REDUCED TO $7500 MUST SELL.
I just finished real world testing on MTV-15B and Hartzell Blended airfoil
on Oct 31. I have a Mattituck TMX-IO-360 on RV7A.
Thought I would share my findings:
At 6000 ft, 2400 RPM Hartzell is faster by 1.8 kts.
At 6000 ft, 2500 RPM Hartzell is faster by 2.5 kts.
Rate of climb from 4000 to 6000 ((at)110 kts IAS) Hartzell is faster by 157 fpm
At 9000 ft, 2400 RPM Hartzell is faster by 1.4 kts.
At 9000 ft, 2500 RPM Hartzell is faster by 3.1 kts
Rate of climb from 7000 to 9000 ((at)110 kts) Hartzell is faster by 209 fpm
Other observations (lessons learned) people may not consider:
1. Hartzell is 11 lbs heavier (55 vs 44 lbs). Recalculate C of G
2. Because of its greater mass, engine is harder to start with Hartzell
3. Because of its greater mass, engine takes longer to shut down. This
really surprised me. My MT would stop very quickly (within 1 engine
revolution), the Hartzell averages 3-4 revolutions before stopping. This
sometime causes it to turn past the 10-4 o'clock position where the MT would
stop every time.
4. The Hartzell takes longer to change pitch. This is evident when adding
power fast. During several overshoots I pushed in the power quickly and RPM
would exceed 2750 and cause the engine warning to flash. The prop caught up
quickly (back to 2700) but this was never an issue with the MT. Same with
initial take-off. Add power slowly with Hartzell.
5. MT is smoother. At 2400 RPM Hartzell is good but at 2300 RPM it has
noticeably more vibration. I'm going to dynamically balance the Hartzell.
6. MT is a bolt on and forget. Spinner made and no grease nipples to worry
about. Hartzell you need to make the spinner, backing plates, etc. Putting
on the MT prop takes 1/2 hour. Hartzell takes ~12 hours of labour.
So both props in my opinion are good. Very close in performance. People
claiming 10 kts increase between the two may need to review the flight test
technique, speed calculations, and consider other factors.
I'm going to sell my MT prop eventually if any early takers out there. Total
flight time on it is 136.5 hours.
Steve
RV7A
Hi Steve-
I've got a prop, but what was the outcome of the testing, aside from
selling the MT? Enquiring minds want to know!
| Quote: | Removed from RV7A IO-360 for flight testing other props.
Steve
|
glen matejcek
aerobubba(at)earthlink.net
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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rtitsworth
Joined: 16 Jan 2006
Posts: 76
Location: Detroit, Mi
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| Posted: Mon Nov 12, 2007 5:37 am Post subject: Propeller for sale |
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Steve,
Thanks for sharing the results of your testing! Curious...
1) For our benefit, were the altitudes below density altitudes (versus
indicated)?
2) Also, how did you measure speed to .1 knots?
3) Did you attempt each maneuver (i.e. best rate of climb) multiple times to
understand the potential variability in technique etc?
4) Any other insights to can share from your testing approach?
Rick
--
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hurlbut(at)ns.sympatico.c
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| Posted: Tue Nov 13, 2007 5:07 am Post subject: Propeller for sale |
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Yes density altitudes. The tests were done 3 days apart and OAT and
altimeter setting were almost equal at altitude.
Yes I measured it to 0.1 kts using 3 way GPS heading. For each RPM (2400 &
2500) and each altitude (6000 & 9000) the test was performed 4 times (and
results averaged). 0.1 kts is difficult to measure but I actually recorded
the GPS speed every second for 3 mins (using a laptop & GNS430 & GNC300XL).
The values were then entered into Excel spreadsheet and observed if the
speed settled out. I decided before the test if the variation was greater
than 0.5 kts, I would discard the data. This only occurred once during the
test. Typically the variation near the end of the run was 0.3 kts so I
consider the error in the measurements to be +- 0.15 kts. To get the actual
TAS a excel spreadsheet was again used. The speeds are not averaged but
instead vectors determined, wind, actual mag heading, etc. This is a normal
flight test technique that is well known.
Again the best rate of climb was performed 4 times each and timed. Feet per
minute calculated.
Other insights? Not much beyond what I wrote earlier. I did perform the
test on 3 headings 000, 120, and 240 degrees but you can actually use any
reasonable headings. Not 090, 091, and 092 obviously but they don't need to
be 120 degrees apart. You just need 3 vector data. I flew the legs both
with autopilot (2 axis) on and off. The error with each was about the same.
Of course recording the data with autopilot on is easier. Also try and
record as much data was you can by voice or recording equipment. I did
write some stuff down but for example during the start of the climb I wanted
to record OAT, MP, start the clock, and ensure maintaining exactly 110 kts
IAS. Hard to write these things down sometimes. Another thing to keep in
mind is it can be beneficial to record magnetic heading as well. A vector
calculation later can provide your actual magnetic heading and therefore the
error in your compass. And easy compass swing although you'll only have data
for the 3 headings you flew on. And of course make (especially for the
climb tests) sure your airspeed ind is accurate.
Steve
RV7A
| Quote: | Steve,
Thanks for sharing the results of your testing! Curious...
1) For our benefit, were the altitudes below density altitudes (versus
indicated)?
2) Also, how did you measure speed to .1 knots?
3) Did you attempt each maneuver (i.e. best rate of climb) multiple times
to
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| Quote: | understand the potential variability in technique etc?
4) Any other insights to can share from your testing approach?
Rick
|
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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