a8.5x7.25 on a OS 46 story in magazine
01-29-2007, 01:01 PM
#1
a8.5x7.25 on a OS 46 story in magazine
this article about the shriek in the modlers magazine this month from AMA has a point abput useing an apc 8.5x7.25 in which I looked up and they dont make that size, well it was on a shreik with a regular OS BB 46 an it was an APC pylon Racing prop , is this possible without burning up the motor??
01-29-2007, 01:15 PM
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RE: a8.5x7.25 on a OS 46 story in magazine
Yes, it is an APC prop.
The 8.5x7 and 8.5x7.25 are D-1 series Q-500 props.
LP08570 8.5X7.0
LP085725 8.5X7.25
LP08575 8.5X7.5
Although you may be correct .... APC may have discontinued the 7.25 version (per the website)
They are not AMA428 racing legal, but they were very popular for SEMPRA and CAPS racing using the Jett SS-40 sport racing engine.
On this engine, they typically tached around 19,500-20,000 rpm for launch.
The OS engine is quite capable, and very durable. No reason it should not be able to turn upward of 18,000 or so without a problem.
On the stock muffler, the 8.5x7.25 or 8.5x7.5 might reach up toward 17,000 on the ground.
With a pipe or jett-stream or ultra-thrust muffler, you might see a little better.
The engine will take it.
Although most of my experience has been with the OS46FX (and with the Thunder Tiger .46 Pro). Others may chime in here as to the capability of the .46AX.
My understanding of the .46AX is that it likes bigger props, tends not to like to run as well much over 15,000 rpm
DaveN ..... perhaps you can better comment on the AX ?
Bob
The 8.5x7 and 8.5x7.25 are D-1 series Q-500 props.
LP08570 8.5X7.0
LP085725 8.5X7.25
LP08575 8.5X7.5
Although you may be correct .... APC may have discontinued the 7.25 version (per the website)
They are not AMA428 racing legal, but they were very popular for SEMPRA and CAPS racing using the Jett SS-40 sport racing engine.
On this engine, they typically tached around 19,500-20,000 rpm for launch.
The OS engine is quite capable, and very durable. No reason it should not be able to turn upward of 18,000 or so without a problem.
On the stock muffler, the 8.5x7.25 or 8.5x7.5 might reach up toward 17,000 on the ground.
With a pipe or jett-stream or ultra-thrust muffler, you might see a little better.
The engine will take it.
Although most of my experience has been with the OS46FX (and with the Thunder Tiger .46 Pro). Others may chime in here as to the capability of the .46AX.
My understanding of the .46AX is that it likes bigger props, tends not to like to run as well much over 15,000 rpm
DaveN ..... perhaps you can better comment on the AX ?
Bob
01-29-2007, 01:21 PM
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RE: a8.5x7.25 on a OS 46 story in magazine
The AX just doesn't go any faster at 16,000 as it does at 14,500.
Anything over about 14,500 is wasted from my use of this engine.
Anything over about 14,500 is wasted from my use of this engine.
01-29-2007, 01:49 PM
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RE: a8.5x7.25 on a OS 46 story in magazine
ORIGINAL: daven
The AX just doesn't go any faster at 16,000 as it does at 14,500.
Anything over about 14,500 is wasted from my use of this engine.
The AX just doesn't go any faster at 16,000 as it does at 14,500.
Anything over about 14,500 is wasted from my use of this engine.
01-29-2007, 01:53 PM
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RE: a8.5x7.25 on a OS 46 story in magazine
ORIGINAL: daven
The AX just doesn't go any faster at 16,000 as it does at 14,500.
Anything over about 14,500 is wasted from my use of this engine.
The AX just doesn't go any faster at 16,000 as it does at 14,500.
Anything over about 14,500 is wasted from my use of this engine.
I've only run one of these so far, and I know you had some experience with it ....
your info is about the same as what I see with the AX.
01-29-2007, 03:21 PM
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RE: a8.5x7.25 on a OS 46 story in magazine
The article I had read listed the torque peak in the low 14,000' (I think it was 14,200). A 10x7 APC prop on most AX engines will peak right about there. A well broken in AX with head shim and baffle removed will peak closer to 14,500.
01-29-2007, 03:41 PM
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RE: a8.5x7.25 on a OS 46 story in magazine
ORIGINAL: daven
The article I had read listed the torque peak in the low 14,000' (I think it was 14,200). A 10x7 APC prop on most AX engines will peak right about there. A well broken in AX with head shim and baffle removed will peak closer to 14,500.
The article I had read listed the torque peak in the low 14,000' (I think it was 14,200). A 10x7 APC prop on most AX engines will peak right about there. A well broken in AX with head shim and baffle removed will peak closer to 14,500.
MJD
01-29-2007, 06:00 PM
#8
RE: a8.5x7.25 on a OS 46 story in magazine
ORIGINAL: bob27s
Yes, it is an APC prop.
The 8.5x7 and 8.5x7.25 are D-1 series Q-500 props.
LP08570 8.5X7.0
LP085725 8.5X7.25
LP08575 8.5X7.5
Although you may be correct .... APC may have discontinued the 7.25 version (per the website)
They are not AMA428 racing legal, but they were very popular for SEMPRA and CAPS racing using the Jett SS-40 sport racing engine.
On this engine, they typically tached around 19,500-20,000 rpm for launch.
The OS engine is quite capable, and very durable. No reason it should not be able to turn upward of 18,000 or so without a problem.
On the stock muffler, the 8.5x7.25 or 8.5x7.5 might reach up toward 17,000 on the ground.
With a pipe or jett-stream or ultra-thrust muffler, you might see a little better.
The engine will take it.
Although most of my experience has been with the OS46FX (and with the Thunder Tiger .46 Pro). Others may chime in here as to the capability of the .46AX.
My understanding of the .46AX is that it likes bigger props, tends not to like to run as well much over 15,000 rpm
DaveN ..... perhaps you can better comment on the AX ?
Bob
Yes, it is an APC prop.
The 8.5x7 and 8.5x7.25 are D-1 series Q-500 props.
LP08570 8.5X7.0
LP085725 8.5X7.25
LP08575 8.5X7.5
Although you may be correct .... APC may have discontinued the 7.25 version (per the website)
They are not AMA428 racing legal, but they were very popular for SEMPRA and CAPS racing using the Jett SS-40 sport racing engine.
On this engine, they typically tached around 19,500-20,000 rpm for launch.
The OS engine is quite capable, and very durable. No reason it should not be able to turn upward of 18,000 or so without a problem.
On the stock muffler, the 8.5x7.25 or 8.5x7.5 might reach up toward 17,000 on the ground.
With a pipe or jett-stream or ultra-thrust muffler, you might see a little better.
The engine will take it.
Although most of my experience has been with the OS46FX (and with the Thunder Tiger .46 Pro). Others may chime in here as to the capability of the .46AX.
My understanding of the .46AX is that it likes bigger props, tends not to like to run as well much over 15,000 rpm
DaveN ..... perhaps you can better comment on the AX ?
Bob
01-30-2007, 09:38 AM
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RE: a8.5x7.25 on a OS 46 story in magazine
Idunno...
Id imagine so.
If anything is going to let go, it will be the rod.
In any case here..... we are talking about a Shrike. Its quick, but it is a bit draggy. That 8.5"x7 size is not the best prop selection in that application (not guessing here, from experience).
Needs prefereably a 9x6, 9x7, 9x8 standard blade, or one of the bigger D-1 seriese props like a 8.75x8 or 8.8x8.5 for any of the engines you mentioned.
Take the OS46FX, Mag46, or any compariable clone - with the stock muffler - target the peak ground rpm between 15,500 and 16,000 rpm with your prop selection. On an OS AX, target 14,500 peak ground rpm. If you choose to upgrade to a tuned muffler, target the same rpm range - you will just be able to go up in pitch a bit.
Bob
Id imagine so.
If anything is going to let go, it will be the rod.
In any case here..... we are talking about a Shrike. Its quick, but it is a bit draggy. That 8.5"x7 size is not the best prop selection in that application (not guessing here, from experience).
Needs prefereably a 9x6, 9x7, 9x8 standard blade, or one of the bigger D-1 seriese props like a 8.75x8 or 8.8x8.5 for any of the engines you mentioned.
Take the OS46FX, Mag46, or any compariable clone - with the stock muffler - target the peak ground rpm between 15,500 and 16,000 rpm with your prop selection. On an OS AX, target 14,500 peak ground rpm. If you choose to upgrade to a tuned muffler, target the same rpm range - you will just be able to go up in pitch a bit.
Bob
