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Jimmy Young
Joined: 24 Nov 2007
Posts: 182
Location: Missouri City, TX
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 Posted: Sun Apr 17, 2011 11:35 am Post subject: Prop MOI |
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I ran the Rotax Service Info propeller mass moment of inertia test today on both my Powerfin 66" 2-Blade & the Warp Drive 64" 3-Blade props. Here is what I found:
Powerfin: weight, 3.03 kg
seconds required for 30 occillations, 162
MOI, 2700 kgcm^
Warp Drive: weight, 4.09 kg
seconds required for 30 occillations, 180
MOI, 4500 kgcm^
Since the max. MOI for the HKS "B" box is 3000 kgcm^, I've put the Powerfin back on for now. The Warp Drive was smoother & performed better in climb and cruise on the nice/still/calm Tuesday morning I tested it, about 100 - 150 fpm climb increase and incrementally better cruise of 2 mph. What I thought was most impressive about it was I could maintain altitude at 4400 rpm vs. 4700 rpm with the Powerfin. The only conclusion I can draw from that is the Warp must be a more efficient prop on my particular plane.
Both props made the engine run very rough if the idle speed drops to less than 1800 rpm, but both were fine once rpm's go over 2000. From what I've learned, at low idle is where most of the conflict occurs. I've always had my HKS set to idle at about 2200 rpm once it's warmed up.
What I'm looking for is a more durable prop, which is why I wanted to use a Warp Drive. I'd like to find out what a WD 2-Blade 66" prop's MOI is without having to buy one first. My guess would be it would slightly exceed the 3000 kg limit, but if it were just by a little bit I wouldn't be concerned.
I haven't been flying all that long, so I'm not up to date about what many of the 503 "B" box powered Kolbs that have WD props are using. The 3000 kg MOI limit applies to them as well. Can any of you long-time veterans of our sport shed any light on that?
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Jimmy Young
Missouri City, TX
Kolb FS II/HKS 700 |
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Sun Apr 17, 2011 1:26 pm Post subject: Prop MOI |
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Jimmy, You might consider having the WD's blades tapered and the stainless leading edge removed. Both will lower the MOI of the prop since you are removing mass where it has the most effect, out at the tips. Doing that should help considerably. Personally, I don't think many people do the MOI test, even though, as you've found out, it's pretty simple, and there's a lot of misinformation about it. One fellow I know believes that Warp Drive props have an MOI up around 10,000.
How long have you run the WD? Have you gone a full oil change interval? If you didn't change out the oil drain plug for one with a magnet on it, run a magnet through your old oil at the next change. If the WD is causing problems iron on the magnet is your early warning signal. I have the 3.47 gearbox that has the higher MOI limit and I run a four blade Powerfin on my trike, but it still made a lot of metal during the first 50 hours until the gears were run in. Every oil change has been clean since then.
There may be another benefit to having the blades tapered, too. One of our EAA chapter members works with Paul Lipps on the Ellipse props. He did a presentation on propeller design at our meeting last Friday night. One of his claims was that a propeller with a constant chord planform, like yours and mine, is like having a wing with wing tips eight times as wide, chordwise, as the wing root. I started planning on having my blades tapered right then.
Rick Girard
On Sun, Apr 17, 2011 at 2:35 PM, Jimmy Young <jdy100(at)comcast.net (jdy100(at)comcast.net)> wrote:
| Quote: | --> Kolb-List message posted by: "Jimmy Young" <jdy100(at)comcast.net (jdy100(at)comcast.net)>
I ran the Rotax Service Info propeller mass moment of inertia test today on both my Powerfin 66" 2-Blade & the Warp Drive 64" 3-Blade props. Here is what I found:
Powerfin: weight, 3.03 kg
seconds required for 30 occillations, 162
MOI, 2700 kgcm^
Warp Drive: weight, 4.09 kg
seconds required for 30 occillations, 180
MOI, 4500 kgcm^
Since the max. MOI for the HKS "B" box is 3000 kgcm^, I've put the Powerfin back on for now. The Warp Drive was smoother & performed better in climb and cruise on the nice/still/calm Tuesday morning I tested it, about 100 - 150 fpm climb increase and incrementally better cruise of 2 mph. What I thought was most impressive about it was I could maintain altitude at 4400 rpm vs. 4700 rpm with the Powerfin. The only conclusion I can draw from that is the Warp must be a more efficient prop on my particular plane.
Both props made the engine run very rough if the idle speed drops to less than 1800 rpm, but both were fine once rpm's go over 2000. From what I've learned, at low idle is where most of the conflict occurs. I've always had my HKS set to idle at about 2200 rpm once it's warmed up.
What I'm looking for is a more durable prop, which is why I wanted to use a Warp Drive. I'd like to find out what a WD 2-Blade 66" prop's MOI is without having to buy one first. My guess would be it would slightly exceed the 3000 kg limit, but if it were just by a little bit I wouldn't be concerned.
I haven't been flying all that long, so I'm not up to date about what many of the 503 "B" box powered Kolbs that have WD props are using. The 3000 kg MOI limit applies to them as well. Can any of you long-time veterans of our sport shed any light on that?
--------
Jimmy Young
Missouri City, TX
Kolb FS II/HKS 700
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=337239#337239
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Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
[quote][b]
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The smallest miracle right in front of you is enough to make you happy.... |
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Jimmy Young
Joined: 24 Nov 2007
Posts: 182
Location: Missouri City, TX
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| Posted: Sun Apr 17, 2011 4:18 pm Post subject: Re: Prop MOI |
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| Quote: | | You might consider having the WD's blades tapered and the stainless leading edge removed. |
Rick,
I'll talk with WD tomorrow & see what suggestions they have. I should have done my research before I bought the prop, so it is on me. Maybe tapering the blades could solve the problem, since an 8.25 lb., 64" 3-blade GSC prop has an MOI of 3200 kgcm^. If tapering took 4 oz. off each blade, I should be close.
Kolb Folks,
For those who are interested in the prop inertia test, here is a pdf file from Rotax Service. I found this doing an archive search, so this is not new info - it has been posted on the Kolb List before.
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Download |
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11ul91-2.pdf |
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_________________
Jimmy Young
Missouri City, TX
Kolb FS II/HKS 700 |
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slyck(at)frontiernet.net
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| Posted: Sun Apr 17, 2011 4:39 pm Post subject: Prop MOI |
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Jimmy, although I'm not running a rotax, I get good performance from a 70" two blade WD and the weight should be
closer to what you should have. Two blade hub is expensive though.
BB
On 17, Apr 2011, at 3:35 PM, Jimmy Young wrote:
| Quote: |
I ran the Rotax Service Info propeller mass moment of inertia test today on both my Powerfin 66" 2-Blade & the Warp Drive 64" 3-Blade props. Here is what I found:
Powerfin: weight, 3.03 kg
seconds required for 30 occillations, 162
MOI, 2700 kgcm^
Warp Drive: weight, 4.09 kg
seconds required for 30 occillations, 180
MOI, 4500 kgcm^
Since the max. MOI for the HKS "B" box is 3000 kgcm^, I've put the Powerfin back on for now. The Warp Drive was smoother & performed better in climb and cruise on the nice/still/calm Tuesday morning I tested it, about 100 - 150 fpm climb increase and incrementally better cruise of 2 mph. What I thought was most impressive about it was I could maintain altitude at 4400 rpm vs. 4700 rpm with the Powerfin. The only conclusion I can draw from that is the Warp must be a more efficient prop on my particular plane.
Both props made the engine run very rough if the idle speed drops to less than 1800 rpm, but both were fine once rpm's go over 2000. From what I've learned, at low idle is where most of the conflict occurs. I've always had my HKS set to idle at about 2200 rpm once it's warmed up.
What I'm looking for is a more durable prop, which is why I wanted to use a Warp Drive. I'd like to find out what a WD 2-Blade 66" prop's MOI is without having to buy one first. My guess would be it would slightly exceed the 3000 kg limit, but if it were just by a little bit I wouldn't be concerned.
I haven't been flying all that long, so I'm not up to date about what many of the 503 "B" box powered Kolbs that have WD props are using. The 3000 kg MOI limit applies to them as well. Can any of you long-time veterans of our sport shed any light on that?
--------
Jimmy Young
Missouri City, TX
Kolb FS II/HKS 700
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=337239#337239
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jbhart(at)onlyinternet.ne
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| Posted: Sun Apr 17, 2011 7:22 pm Post subject: Prop MOI |
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At 05:18 PM 4/17/11 -0700, you wrote:
| Quote: |
I'll talk with WD tomorrow & see what suggestions they have. I should have
done my research before I bought the prop, so it is on me. Maybe tapering
|
the blades could solve the problem, since an 8.25 lb., 64" 3-blade GSC prop
has an MOI of 3200 kgcm^. If tapering took 4 oz. off each blade, I should be
close.
Jimmy,
Ask them if they will loan you a two blade hub so you can see how it
performs. It looks like a two blade may make it in under the inertia
limit. Crank up the pitch, and it may perform just as well as your
Powerfin.
Jack B. Hart FF004
Winchester, IN
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DAquaNut(at)aol.com
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| Posted: Sun Apr 17, 2011 8:32 pm Post subject: Prop MOI |
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Jimmy,
I have a brand new never installed 64" Warp Drive /with tapered tips and SS LE inlay if you want to check the MOI. I've never installed it because I have always thought it was over the 3000kg. limit
Ed Diebel FF# 62
In a message dated 4/17/2011 2:38:26 P.M. Central Daylight Time, jdy100(at)comcast.net writes:
| Quote: |
What I'm looking for is a more durable prop, which is why I wanted to use a Warp Drive. I'd like to find out what a WD 2-Blade 66" prop's MOI is without having to buy one first. My guess would be it would slightly exceed the 3000 kg limit, but if it were just by a little bit I wouldn't be concerned.
I haven't been flying all that long, so I'm not up to date about what many of the 503 "B" box powered Kolbs that have WD props are using. The 3000 kg MOI limit applies to them as well. Can any of you long-time veterans of our sport shed any light on that?
--------
Jimmy Young
Missouri City, TX
Kolb FS II/HKS 700
|
[quote][b]
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Richard Pike
Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee
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| Posted: Sun Apr 17, 2011 8:58 pm Post subject: Re: Prop MOI |
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Can you go to Mobil 1 synthetic gear oil in the HKS gear box? Since doing that in the Rotax B box, metal on the magnet at oil change has been nil, and the box is notably cooler at the end of each flight than when using mineral oil.
I realize that is irrelevant to MOI, but thinking in terms of how to optimize whatever you end up with...
Richard Pike
MKIII N420P (420ldPoops)
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Mon Apr 18, 2011 5:31 am Post subject: Prop MOI |
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The reply from Flight Designs, when they were the importers of the HKS engine was no, use straight automotive Mobil 1 without the gearbox additives. The HKS, like the Rotax 912 does not have a separate oil supply for the gearbox.
Rick Girard
On Sun, Apr 17, 2011 at 11:58 PM, Richard Pike <richard(at)bcchapel.org (richard(at)bcchapel.org)> wrote:
| Quote: | --> Kolb-List message posted by: "Richard Pike" <richard(at)bcchapel.org (richard(at)bcchapel.org)>
Can you go to Mobil 1 synthetic gear oil in the HKS gear box? Since doing that in the Rotax B box, metal on the magnet at oil change has been nil, and the box is notably cooler at the end of each flight than when using mineral oil.
I realize that is irrelevant to MOI, but thinking in terms of how to optimize whatever you end up with...
Richard Pike
MKIII N420P (420ldPoops)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=337310#337310
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arget="_blank">http://www.matronics.com/Navigator?Kolb-List
===========
http://forums.matronics.com
===========
le, List Admin.
="_blank">http://www.matronics.com/contribution
===========
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--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
[quote][b]
| | - The Matronics Kolb-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?Kolb-List |
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_________________
The smallest miracle right in front of you is enough to make you happy.... |
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Jimmy Young
Joined: 24 Nov 2007
Posts: 182
Location: Missouri City, TX
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| Posted: Mon Apr 18, 2011 6:13 am Post subject: Re: Prop MOI |
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Kolbers,
I just spoke with Daryl (at) Warp Drive.
I would suggest that anyone ordering a Warp Drive prop to make sure you are dealing with the factory in Iowa, where Daryl is. He is 100 times more knowledgeable & helpful than if you purchase through a dealer. When I ordered the prop, I googled Warp Drive and got what I thought was the factory. Turns out it was a distributor, Hoverhawk, who I purchased my prop from. Nice folks, but they in turn just have it drop shipped from Warp Drive. Nothing wrong with that, but when it comes to service no one knows more about a Warp Drive prop than Daryl. He suggested I send the blades to him & he will have them custom tapered based on my prop pitch and rpm info, which should drop the MOI a good bit. Won't know how much till I get it back, but I'm willing to give it a try.
The Warp Drive Factory ph# is 800.833.9357.
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Jimmy Young
Missouri City, TX
Kolb FS II/HKS 700 |
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