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  #11  
Old 12-09-2022, 11:26 AM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
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Quote:
Originally Posted by Taltruda View Post
MT would be my LAST choice.. every MT prop ove seen gets these cracks in the finish. They say itís not structural, but boy are they ugly. Also perhaps itís just a coincidence, but MT props seem slower than other planes. I really like the new stuff coming from WW..
Speed "depends". I picked the BA 2 blade for my Rocket because its the "fastest" according to The Man himself. And at 2700 RPM I handily outpull the MT 3 blade on my buddy's (very fast) F-1. THAT SAID, he crushes me at 2300 RPM, and thats where I spend 90% of my flying time.

Im not a fan of the MT shipping, overhaul ritual and cost to own, but if I had to do it over, I'd probably go that way because on MY AIRPLANE, the MT would provide better performance overall than my Hartzell.

And for the record, I dont give a lot of thought about how a propeller "looks".
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
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Harmon Rocket II -SDS EFI
1940 Taylorcraft BL-65
1984 L39C - SOLD
RV-8 - SDS CPI - SOLD
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  #12  
Old 12-09-2022, 12:59 PM
FlyinTiger FlyinTiger is offline
 
Join Date: Feb 2009
Location: Gilbert, SC
Posts: 359
Lightbulb Kitplanes article WW vs. everyone else

Bang for the buck is probably a two blade Hartzell blended airfoil prop. They can be found used and IRAN'd for a reasonable price.

Whirlwind seems to have a slight edge on performance according to the Kitplanes article on the subject here https://www.kitplanes.com/whirl-wind-300/ but it comes at an increased cost.

Weight and balance can easily be adjusted by adding useful things like a vacuum drive back up alternator if you don't already have one, a second battery up front for your G3X panel back up, or a remote oil cooler bracket/mount which add up quick in weight to compensate for the lighter propeller if you indeed need some ballast up front.

If you're going from a fixed pitch propeller to a composite prop the weight issue is in reverse as in the CS props are almost always heavier than the FP it replaced. Definitely easy to add weight vs. removing it.

Best of luck and let us know which direction you go. It is a bit disconcerning that WW isn't getting back to you in a timely manner, lets hope everything is going well over there.
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  #13  
Old 12-09-2022, 01:06 PM
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Tankerpilot75 Tankerpilot75 is offline
 
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Location: Oklahoma City, OK
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If you can overhaul your prop that by far is the least expensive option and probably the fastest. I had a prop strike at Airventure this year and my Hartzell BA prop was toast ( Dug a trench with it). Looked at ordering a new Hartzell BA but the wait time was truly excessive (7 plus months at least) with a price over $17.5K.

Explored other options and decided the MT three blade with the heavy duty hub,in my case, was an excellent option. Several people I know have the prop and were satisfied. The advantages over a WW were the lack of annual maintenance requirements and a 2,500 hour overhaul versus 500 hours for the WW. Also, MT doesn’t impose any rpm restrictions for EI systems as Hartzell does and I’m converting to dual PMags with the tear down/rebuild. Availability through MacFarland was immediate and at a lesser price than the Hartzell.

I’m told the three blade MT9 that I’m getting will be smoother, quieter and lighter than my Hartzell. Since my RV7A is a bit of a porker (1,187 lbs) a few pound weight reduction is not a bad thing. Performance, I’m told, is better in climb and cruise but top speed will likely be a few knots lower. Since I don’t fly near Vne that shouldn’t be an issue. We’ll see pretty soon.
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Jim Harris, 2008 RV7A, 2nd owner, N523RM (2015) Superior XPIO-360 B1AA2, MT9 CS prop, Two PMags, Dual GRT Horizon EX with ARINC, EIS, Garmin 340, 335 w/WAAS gps, Dual 430s (non-WAAS), TruTrak 385 A/P with auto level & trim, Tosten 6 button Military Grips, FlightBox wired to EX, Dynon D10A w/battery backup, 406 MHz ELT, Mountain High O2, CO2 monitor, Custom Interior, TS Flightline hoses, ETX900 Battery, Bruce Cover

Retired - Living the dream - going broke!

Last edited by Tankerpilot75 : 12-09-2022 at 04:32 PM.
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  #14  
Old 12-09-2022, 04:12 PM
Taltruda Taltruda is offline
 
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Originally Posted by Toobuilder View Post
Speed "depends". I picked the BA 2 blade for my Rocket because its the "fastest" according to The Man himself. And at 2700 RPM I handily outpull the MT 3 blade on my buddy's (very fast) F-1. THAT SAID, he crushes me at 2300 RPM, and thats where I spend 90% of my flying time.

Im not a fan of the MT shipping, overhaul ritual and cost to own, but if I had to do it over, I'd probably go that way because on MY AIRPLANE, the MT would provide better performance overall than my Hartzell.

And for the record, I dont give a lot of thought about how a propeller "looks".
Iíll second the fact that the MT prop doesnít seem to lose speed at lower RPMs.. I delivered a -7 and it was the same speed at 2700 as it was at 2100 rpm. It didnít seem to care.
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  #15  
Old 12-10-2022, 11:26 AM
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flyin_jibbs flyin_jibbs is offline
 
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Location: South Lake Tahoe
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Originally Posted by lr172 View Post
Are you sure you are OK with 2 passengers with 0 allotment for baggage? Would seem to be a large hit to the plane's utility. I added a 20# crush plate to my 6A. DOn't like what it does to handling, but was unwilling to settle on 15-20#'s of baggage with a passenger.

Larry
Larry, thanks for brining that up! You're right! I hadn't done those configurations because for me that flight scenario is very last/most unlikely on my list of use cases. However, after reading your thoughts, I definitely needed to run those numbers on 4 more configurations, and you're right.

Whether its me and a 200lb buddy or the wife and I, with full fuel and 75lbs in back i barely keep it inside and of course as fuel starts getting down there it works its way out of CG.

(Conversely if its Me and 200lb buddy or the wife and I and 0 baggage, Full and Low fuel, it stays in CG in all 4 of those configurations)

Again for my use case, these scenarios would be the least used, if ever, configuration. The only person id really ever travel with along with alot of baggage would be the wife, and Im pretty confident that will never happen (a: she's not a fan of flying and b: when we travel together for anything overnight we have to take the SD Tremor along with our two 110lb Rotties, (also no kids) they're too much to leave in the hands of other people).

And when/if I go out to camp or fish with my buds, well, they have their own rides

My use case will be primarily travel for work while having alot of fun doing it!! Of course along with joy riding and lunch runs etc. But after 15 years of commercial travel im over TSA and all their silliness, layovers, lost bags, cancelations, weirdos sleeping on you etc hah!

Now Im finding myself stuck on the 2 vs 3 blade dilemma which again will further inhibit the 2 people + bags envelope (1lb difference from my weight with these aforementioned calcs).

So overall, you're right it does inhibit the utility a bit, but nothing that will take away from my user experience. And if that time comes when its important, well, maybe I can convince the wife I need another plane

Sorry for the long winded response but making this thread was actually very helpful so thanks!

Last edited by flyin_jibbs : 12-10-2022 at 11:37 AM.
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  #16  
Old 12-10-2022, 01:16 PM
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Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
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Quote:
Originally Posted by Taltruda View Post
Iíll second the fact that the MT prop doesnít seem to lose speed at lower RPMs.. I delivered a -7 and it was the same speed at 2700 as it was at 2100 rpm. It didnít seem to care.
You should not assume any propeller has a linear efficiency curve over a range of RPMs.

For MPG, I found my two bladed, 74Ē Hartzell BA to have best cruise efficiency at 2480 RPM. This drops off (slowly) at both higher and lower RPM settings. Best to do careful data runs to determine your own sweet spot as there are many variables at play.

My new cruise sweet spot is 2480 and 9Kí (RV-8, IO-360M1B with AFP FM-150C).

Carl
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