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IMAC Prop Selection????

Old 10-05-2009, 08:22 PM
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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
Old 10-05-2009, 08:30 PM
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Default RE: IMAC Prop Selection????

Tom,

I'm using a 29x12 Mejlik<sp> 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
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.
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
Old 10-06-2009, 08:38 AM
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Default RE: IMAC Prop Selection????


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
Old 10-07-2009, 07:13 PM
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Default RE: IMAC Prop Selection????

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
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
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.

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
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
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.
Old 02-11-2010, 10:47 AM
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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
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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