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ces308
Joined: 03 Nov 2008
Posts: 317
Location: houghton lake ,mi
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 Posted: Wed Aug 11, 2010 2:06 am Post subject: A2200 rpm's |
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Hello all...
I was running a Sensenich 58-44 prop that was giving me 31-3300 on take off and worked just fine .I put an Arrowprop 58-44 on and can only get 2650 on take off.I have a new Sensenich coming...my question is,am I hurting the engine at all running the Arrowprop at the lower rpm until I get my other prop??
Thanks,
chris ambrose
M3X Kolb / Jabiru A-2200 ser # 1228 141.8 hrs
N327CS
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Wed Aug 11, 2010 2:36 am Post subject: A2200 rpm's |
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The answer is possibly. It's like trying to start your car rolling in third gear instead of first. The main thing you are losing is horsepower. Excess horsepower is what makes climbing possible.You might ask how two propellers rated as having the same pitch can have such wildly differing performance on your aircraft. The answer is that there is no specification about where or how that measurement is taken. One prop make might measure the pitch at the 75% of diameter point and use the bottom of the prop as the reference surface. Another might use the prop tip and the chord of the propeller airfoil.
I have used this example on the Kolb forum so you might have seen it there. Bear with me.
Several years ago, before I made the decision to go LSA, I was building a LongEZ. I was offered a propeller made by a known maker that was reputed to be optimized for the engine I intended to use. It had been done by Don Bates, author of the prop optimizer program, himself. I eventually sold the prop to a Varieze owner with the correct engine for it. He bought the prop on condition that he be able to mount and try it first, and we agreed. While he wasn't that impressed with the prop, it was at least as good as what he was running so he bought it as a spare. A few months later he contacted the props maker about having it reworked for a little more performance. Said prop maker was the new owner of the brand and not the original carver who had created it. When my buddy got the prop back he could tell that the blades were a little thinner, but the new carver claimed it was still the same pitch as before. I got a call the evening after he mounted and flew the newly modified propeller. His Varieze, with no other modifications, just putting on the propeller, was 40 MPH faster.
My point is that those numbers, 58 X 44 are relative, only testing and investigation will tell you what they are relative to.
Rick Girard
On Wed, Aug 11, 2010 at 5:06 AM, ces308 <ces308(at)ldaco.com (ces308(at)ldaco.com)> wrote:
[quote]--> JabiruEngine-List message posted by: "ces308" <ces308(at)ldaco.com (ces308(at)ldaco.com)>
Hello all...
I was running a Sensenich 58-44 prop that was giving me 31-3300 on take off and worked just fine .I put an Arrowprop 58-44 on and can only get 2650 on take off.I have a new Sensenich coming...my question is,am I hurting the engine at all running the Arrowprop at the lower rpm until I get my other prop??
Thanks,
chris ambrose
M3X Kolb / Jabiru A-2200 ser # 1228 141.8 hrs
N327CS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=308335#308335
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http://forums.matronics.com
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le, List Admin.
="_blank">http://www.matronics.com/contribution
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[b]
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The smallest miracle right in front of you is enough to make you happy.... |
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naftalih(at)hotmail.com
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| Posted: Wed Aug 11, 2010 5:44 am Post subject: A2200 rpm's |
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Wxtra 40 mph seems exaggerated
Date: Wed, 11 Aug 2010 05:36:13 -0500
Subject: Re: A2200 rpm's
From: aslsa.rng(at)gmail.com
To: jabiruengine-list(at)matronics.com
The answer is possibly. It's like trying to start your car rolling in third gear instead of first. The main thing you are losing is horsepower. Excess horsepower is what makes climbing possible. You might ask how two propellers rated as having the same pitch can have such wildly differing performance on your aircraft. The answer is that there is no specification about where or how that measurement is taken. One prop make might measure the pitch at the 75% of diameter point and use the bottom of the prop as the reference surface. Another might use the prop tip and the chord of the propeller airfoil.
I have used this example on the Kolb forum so you might have seen it there. Bear with me.
Several years ago, before I made the decision to go LSA, I was building a LongEZ. I was offered a propeller made by a known maker that was reputed to be optimized for the engine I intended to use. It had been done by Don Bates, author of the prop optimizer program, himself. I eventually sold the prop to a Varieze owner with the correct engine for it. He bought the prop on condition that he be able to mount and try it first, and we agreed. While he wasn't that impressed with the prop, it was at least as good as what he was running so he bought it as a spare. A few months later he contacted the props maker about having it reworked for a little more performance. Said prop maker was the new owner of the brand and not the original carver who had created it. When my buddy got the prop back he could tell that the blades were a little thinner, but the new carver claimed it was still the same pitch as before. I got a call the evening after he mounted and flew the newly modified propeller. His Varieze, with no other modifications, just putting on the propeller, was 40 MPH faster.
My point is that those numbers, 58 X 44 are relative, only testing and investigation will tell you what they are relative to.
Rick Girard
On Wed, Aug 11, 2010 at 5:06 AM, ces308 <ces308(at)ldaco.com (ces308(at)ldaco.com)> wrote:
[quote]--> JabiruEngine-List message posted by: "ces308" <ces308(at)ldaco.com (ces308(at)ldaco.com)>
Hello all...
I was running a Sensenich 58-44 prop that was giving me 31-3300 on take off and worked just fine .I put an Arrowprop 58-44 on and can only get 2650 on take off.I have a new Sensenich coming...my question is,am I hurting the engine at all running the Arrowprop at the lower rpm until I get my other prop??
Thanks,
chris ambrose
M3X Kolb / Jabiru A-2200 ser # 1228 141.8 hrs
N327CS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=308335#308335
===========
-List" target="_blank">http://www.matronics.com/Navigator?JabiruEngine-List
===========
http://forums.matronics.com
===========
le, List Admin.
="_blank">http://www.matronics.com/contribution
===========
-List" target=_blank>http://www.matronics.com/Navigator?JabiruEngine-List
ttp://forums.matronics.com
=_blank>http://www.matronics.com/contribution
[b]
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dons701
Joined: 22 May 2009
Posts: 80
Location: Hershey, PA
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| Posted: Wed Aug 11, 2010 6:28 am Post subject: Re: A2200 rpm's |
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Hi Chris
Another consideration is the fuel rate at the new RPM. It would be interesting to see your full throttle EGT's with the two different props. I may be wrong, but I believe you could be running leaner at full throttle with the lower RPM prop.
Don
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Zenith 701 #76120
Jabiru 2200A #2456 95 hours
Sensenich Wood 64-PJ-36 Prop |
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Wed Aug 11, 2010 9:04 am Post subject: A2200 rpm's |
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The pilot in question was ex military and life long pilot. I've known him for almost 10 years and I do not doubt his report, he is a pretty careful guy. You're free to feel as you wish, though, that's democracy.
Rick
On Wed, Aug 11, 2010 at 8:43 AM, Naftali Horowitz <naftalih(at)hotmail.com (naftalih(at)hotmail.com)> wrote:
[quote] Wxtra 40 mph seems exaggerated
Date: Wed, 11 Aug 2010 05:36:13 -0500
Subject: Re: A2200 rpm's
From: aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)
To: jabiruengine-list(at)matronics.com (jabiruengine-list(at)matronics.com)
The answer is possibly. It's like trying to start your car rolling in third gear instead of first. The main thing you are losing is horsepower. Excess horsepower is what makes climbing possible. You might ask how two propellers rated as having the same pitch can have such wildly differing performance on your aircraft. The answer is that there is no specification about where or how that measurement is taken. One prop make might measure the pitch at the 75% of diameter point and use the bottom of the prop as the reference surface. Another might use the prop tip and the chord of the propeller airfoil.
I have used this example on the Kolb forum so you might have seen it there. Bear with me.
Several years ago, before I made the decision to go LSA, I was building a LongEZ. I was offered a propeller made by a known maker that was reputed to be optimized for the engine I intended to use. It had been done by Don Bates, author of the prop optimizer program, himself. I eventually sold the prop to a Varieze owner with the correct engine for it. He bought the prop on condition that he be able to mount and try it first, and we agreed. While he wasn't that impressed with the prop, it was at least as good as what he was running so he bought it as a spare. A few months later he contacted the props maker about having it reworked for a little more performance. Said prop maker was the new owner of the brand and not the original carver who had created it. When my buddy got the prop back he could tell that the blades were a little thinner, but the new carver claimed it was still the same pitch as before. I got a call the evening after he mounted and flew the newly modified propeller. His Varieze, with no other modifications, just putting on the propeller, was 40 MPH faster.
My point is that those numbers, 58 X 44 are relative, only testing and investigation will tell you what they are relative to.
Rick Girard
On Wed, Aug 11, 2010 at 5:06 AM, ces308 <ces308(at)ldaco.com (ces308(at)ldaco.com)> wrote:
| Quote: |
ist" target="_blank">http://www.matronics.com/Navigator?JabiruEngine-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
|
[b]
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_________________
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