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IMAC Prop Selection????

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Old 10-05-2009, 08:22 PM
  #1
tburndrett
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Default IMAC Prop Selection????

OK, I've moved up to a 42% extra 260 powered with a DA170 on MTW 110 cans. Man what a stump puller that engine is!!!!
Question is, now that I am through the break-in on the engine, what prop should I be using? Don't plan on any 3D stuff, just IMAC. I don't what to have to take out another loan against the house (did that for the plane and engine) trying a bunch of props, so thought I would ask. Would like to use a 3-blade like I had on my 33% CA, just not sure what size.

Suggestions??????

Thanks,

Tom
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Old 10-05-2009, 08:30 PM
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Default RE: IMAC Prop Selection????

Tom,

I'm using a 29x12 Mejlik 3-blade on a 42lb Jtec with the same exhaust setup. Nice and quiet and still more than enough power for the uplines with 2 snaps. I suspect that once I get another 5 gallons through it I'll be changing out to a 30x12 3-blade as I can rip the 29x12 if the air is cool enough and I'm only 7 gallons into the engine

A good 30x13 2 blade works fine but you can rip that one pretty good
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Old 10-05-2009, 09:01 PM
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Default RE: IMAC Prop Selection????

Thanks Bill,

I have been running Biela props on my BME110's and have really liked the down line breaking that they give. I just hate to have to spend $150+ on a prop and then not like it! My plane is at 41#'s that 170 pulls it like it is only 30! I debated on the 150, but figured I can alway throttle back!

Thanks again.
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Old 10-05-2009, 09:09 PM
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Default RE: IMAC Prop Selection????

Tom,

Sorry, I cannot give you any input on the Biela. I know a few that use them and love them but no one on a DA170. I suspect that since they are a wider/thicker blade you might be better off with something 3-Blade in the 28 inch range. That would keep the RPM's up and allow for a better upline and still have the downline braking
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Old 10-06-2009, 08:38 AM
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Quote:
ORIGINAL: tburndrett

Thanks Bill,

I have been running Biela props on my BME110's and have really liked the down line breaking that they give. I just hate to have to spend $150+ on a prop and then not like it! My plane is at 41#'s that 170 pulls it like it is only 30! I debated on the 150, but figured I can alway throttle back!

Thanks again.
Hey Guys... Just wanted to give a little input. I flew the DA170 with MTW mufflers for 1 year and 2 months with a 29x12N Mejzlik 3 blade prop on a 40.5 lb Yak 55sp. In July of this year (2009) I changed to a 30x12 two blade Mejzlik and can easily rip it...so I have to be careful on the horizontal. I recently changed to a KS 95 (version 5) mufflers and I instantly gained 240 rpm's over the MTW cans on the 30x12 prop. I could NOT believe it.

Now...like you Tom, I'm looking to change back to a 3 blade prop as the 2 blade prop is too "instantaneous" on the throttle. I would highly suggest to keep looking for the best 3 blade prop... I have not found it as yet.
Wayne
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Old 10-07-2009, 07:13 PM
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Hey Wayne,

Met you at the Nats a couple years ago. How is it going?
Thanks for the input. One additional question, how has your idle been on the 170? I have trouble getting a good reliable idle that is low enough for landing. I am hoping that moving to a larger/heavier prop will help. The problem I have is that the TT-TOC Extra260 just doesn't want to stop flying unless the idle is 1200 or less! Of course, getting use to the landing speed on the 42% plane vs the 33 is taking a little adjustment for the pilot as well. I have a little over 10 gallons through the engine at this point and the idle is getting better. Transition is great and smooth throughout the RPM range.

Just wondering.

Keep Flying....

Tom
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Old 10-08-2009, 06:39 AM
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Hey Tom...the idle is extremely slow & smooth.... I hope you have got all the updates on the 170? I use a solid backplate TruTurn spinner, so it helps to smooth out the idle. You can slow down the airplane with the elevator & use the throttle to vary the altitude...
Wayne
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Old 02-02-2010, 10:00 PM
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Default RE: IMAC Prop Selection????

Hey Tom,

Did you find the prop? Probably not just wondering. Still waiting for warmer days.

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Old 02-03-2010, 07:47 AM
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ORIGINAL: vbortone

Hey Tom,

Did you find the prop? Probably not just wondering. Still waiting for warmer days.

Well... I changed planes to an Extreme Flight 123" Extra 300 with my same DA 170, but this time with KS 1090 tuned pipes. I've tried several props, both two blades & three blades. I have finally settled with the Mejzlik 29x12N as this is the BEST compromise between the 2 & 3 blades for competition. The plane is 42 lbs and she goes....
Wayne
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Old 02-03-2010, 08:23 AM
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Default RE: IMAC Prop Selection????

I have decided to go with the 29X12 as well. It should be here by the end of the week. I too am using a sold backplate on my spinner (TruTurn). What are the updates you are referring to on the engine? Mine is less than a year old, so should be the latest and greatest. At least it hasn't given me any problems after 99 flights.
Now, if only the weather would warm a little - I just can't bring myself to go to the field with temps below freezing! Let you know how it turns out.

Tom
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Old 02-10-2010, 12:53 AM
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Default RE: IMAC Prop Selection????

If you watch your throttle a Mej 30x13 is one of the best. Assuming it doesn't delam.
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Old 02-11-2010, 10:47 AM
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Quote:
ORIGINAL: nmking09

If you watch your throttle a Mej 30x13 is one of the best. Assuming it doesn't delam.
Hey there.... Tom did say in his first post that he wanted to use a 3 blade prop. Maybe you missed that?
I tried the 30x13 Mejzlik 2 weeks ago & it was a noisy prop for IMAC. Even with throttle management you will have trouble with sound. The 29x12N is the best I have found up to now.

Look on the Hall sensor pick-up. Is it turned all the way to the left (retarded)? There were updates to head bolts & other internal areas that are significant. Give Tony a call at Desert Aircraft & let him tell you if your engine has the updates. I am sure they would have it on file.
Wayne
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Old 02-11-2010, 08:09 PM
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Default RE: IMAC Prop Selection????

Wayne,
Yea, I checked and mine is retarded as far a possible. Is that part of the update? I'll try to call Tony tomorrow and check.

Thanks,
Tom
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