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1. 04:19 PM - Re: prop recommendations for 447 on firestar or firefly (Jay Dub)
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| Subject: | Re: prop recommendations for 447 on firestar or firefly |
Thanks for the info on props. I'm still wondering what the dia/pitch of wood props
were for Firestars when they used wood props in the 80's and 90's?
I did call Kolb and talked with Tom this morning. He said they are recommending
the Ivoprop, Powerfin, or the Ultraprop II. They recommend 62-64" dia 2 or 3
blade.
My Ivo can be cut down from 68" to 64" according to Ivo so I might just do that.
Jay
Sent:Thursday, July 13, 2023 at 12:03 PM
From:"Stuart Harner" <stuart@harnerfarm.net>
To:kolb-list@matronics.com
Subject:Re: Kolb-List: prop recommendations for 447 on firestar or firefly
Now that I think about it, I may have mis-spoke about the RPM. It has
been many years since I last flew so I went back and looked at the charts.
I think cruise ~65 takes abut 5800 RPM and I was using 4800 for powered
descents. My Firefly really likes 63 MPH indicated. It will easily go
way faster than that but anything above 65 and you can feel it protesting.
I do remember that I followed the book for initial pitch set up. Full
throttle while tied down should produce "x" RPM. I remember adjusting
the pitch a few times to get this dialed in. After that it was off to
flying but I never had an opportunity to do any really good pattern work
or more tuning on the engine. Just too much traffic at the local
"little" airport. I would take off and get the heck away from there just
to go flying, then run the gauntlet through the traffic going every
which direction to try and land without being run over. Only got about
15 hours in the air before I gave up.
Looking at the Rotax chart for the 447 it says fuel consumption is
supposed to be 4 GPH at 5500 RPM. I never figured it could be anything
much less than maybe 3.5 GPH.
Oh well,
Stuart
On 7/13/23 11:59, Terry Frantz wrote:
>
> Wow! 4Gal per hour is extreme. I have a 66" two blade IVO on my
> Firefly after having replaced the Tennessee 66" prop many years ago.
> 447 B box and have consistently gotten a rate of 2 gal per hour from
> both. Reaching 65 mph at 5000 rpm means your probably over pitched.
> My friend who has a FireStar II with a 503 and a 68" two blade IVO
> gets a little over 2 gal per hour on his. We generally cruise at 4800
> rpm. For what it's worth.
>
>
> On 7/12/2023 7:12 PM, Stuart Harner wrote:
>>
>> My Firefly has a 60" 3 blade Warp Drive on the 447 with a 2.58:1 "B"
>> box.
>>
>> Smooth, quiet and powerful, but I don't get much better than 4 G/Hr.
>> 4800 to 5000 engine RPM will push the Firefly ~65 MPH.
>>
>> The 3 blade makes it fit in the camper/hangar nicely.
>>
>>
>> On 7/12/23 17:31, Jay Dub wrote:
>>>
>>> I have a 68" Ivoprop ground adjustable that came with my 447 (both
>>> used)for my Firestar. Does anyone know what the recommended prop
>>> diameter/pitch is for the 447 powered firestar or firefly? I have
>>> flown with Ivoprops in the past and never cared for them (it seems
>>> the flex/coninggives them a lot of "slip" making them very
>>> inefficient, but I could be wrong). Every ultralight in the 90's I
>>> flew with an ivo burned a lot more fuel than the fixed 60x38 or
>>> 60x40 wood props and took longer in takeoff as well as cruised
>>> slower (my own observations but that was all with CGS Hawks flying
>>> 447s and not Kolbs). Since wood props are just as or more expensive
>>> these days as to a composite, I'm wondering what the wisdom is these
>>> days for a prop? What wood prop came with the 447 firestars or
>>> fireflies of yore? What are the recommended composite props these days?
>>> I had an unmarked (brand) 60x40 wood prop that gave me 60 mph
>>> cruise in a Hawk burning 1.5 gallons an hour consistently. Before
>>> that I had a 60x38 Culver (made in PA) that burned closer to 1.8
>>> gal/hr cruising at 60. I still have the 60x40 but long story short,
>>> it's split from hitting a green jolly rancher candy and that ruined
>>> it so it hangs on my living room wall. I wish I knew the brand as
>>> I'd buy one in a heartbeat but my guess it was a Tennessee prop.
>>>
>>> Thanks,
>>> Jay
>>>
>>>
>>>
>>>
>>
>>
>>
>
>
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