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Cheetah pump value

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Old 11-24-2015, 08:51 PM
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DHC6
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Default Cheetah pump value

This is my first turbine so I am still learning what's "normal" and what's not.

I was was just going through my last flight log and was curious what a normal range should be for pump value, and wondering what it's actually measuring?
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Old 11-25-2015, 07:27 PM
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Originally Posted by DHC6 View Post
This is my first turbine so I am still learning what's "normal" and what's not.

I was was just going through my last flight log and was curious what a normal range should be for pump value, and wondering what it's actually measuring?
For a Cheetah at full throttle it can be between 350 to 600. The lower the better and it depends a lot on your fuel line and any possible restrictions you may have in your fuel system. I like to see mine in the 400 to 550 on a cheetah. But small fuel line, some filters and your fuel vents can cause a higher value. Also if you reach the pump limit you can flame out so make sure that you go to full throttle on the ground and see what your value is.

So so many of us don't even test to make sure that we get full throttle before we take off which I always do just to make sure it's all good as you never know when your filter can be clogged or anything else that could have caused an issue. I'm old school and always look at what my engine is doing before takeoff.
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Old 11-26-2015, 07:33 AM
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I always do a full power run up to make sure I get full power/RPM, however being new to turbines I am unsure of what's normal for some other values.

I am just looking at flight logs again, and the numbers I have for the Pump value are only 2 digit number. My highest being 82 at full power, and idle being 14. I am pretty sure the numbers are not abbreviated either since all the other numbers like EGT, RPM etc. I am using the Xicoy flight computer, and my Cheetah has the powerpack, so I am not sure if the numbers for the pump are represented in a different value.

My fuel system is set up in parallel with 2 saddle tanks and a forward tank. There is also a BVM UAT in the system. All the fuel lines are the larger 1/8th tygon, however I am not sure if the tanks have filters in them or just clunks (bought the plane used) . There is an external fuel filter, so I am pretty sure there are no filters in the tanks. Looks like a pretty "standard set up".
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Old 11-29-2015, 04:42 PM
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Originally Posted by DHC6 View Post
I always do a full power run up to make sure I get full power/RPM, however being new to turbines I am unsure of what's normal for some other values.

I am just looking at flight logs again, and the numbers I have for the Pump value are only 2 digit number. My highest being 82 at full power, and idle being 14. I am pretty sure the numbers are not abbreviated either since all the other numbers like EGT, RPM etc. I am using the Xicoy flight computer, and my Cheetah has the powerpack, so I am not sure if the numbers for the pump are represented in a different value.

My fuel system is set up in parallel with 2 saddle tanks and a forward tank. There is also a BVM UAT in the system. All the fuel lines are the larger 1/8th tygon, however I am not sure if the tanks have filters in them or just clunks (bought the plane used) . There is an external fuel filter, so I am pretty sure there are no filters in the tanks. Looks like a pretty "standard set up".
I would ask you to look at the actual number when running and write them down. There is no way your PW is 82 at full power. Maybe the flight log is not right or if that stands for 820 than it's extremely high. Please look when running and let me know what you have. You can also call me as well.
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Old 12-01-2015, 07:29 PM
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Jose,

I will run the engine again tomorrow, and verify the numbers. However I am fairly certain those are the values that I see when the engine is actually running. I will report back here tomorrow after I run the engine.
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Old 12-02-2015, 11:19 AM
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Ok, so I just ran the engine, and the numbers I saw seem to be more what you guys are saying they should be.

At idle I see a PW value of 78 with a pump voltage of 0.55V
At 50(ish)% throttle PW is 150 with pump voyage at 1.14V
At full power PW is 411 and pump voyage at 3.1V

So do these look more normal? Also what is PW? And does anyone know what PW value I should be putting in the Xicoy flight computer for the fuel level calculation?
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Old 12-11-2015, 07:50 PM
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Hello?
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Old 12-16-2015, 12:06 PM
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Originally Posted by DHC6 View Post
Ok, so I just ran the engine, and the numbers I saw seem to be more what you guys are saying they should be.

At idle I see a PW value of 78 with a pump voltage of 0.55V
At 50(ish)% throttle PW is 150 with pump voyage at 1.14V
At full power PW is 411 and pump voyage at 3.1V

So do these look more normal? Also what is PW? And does anyone know what PW value I should be putting in the Xicoy flight computer for the fuel level calculation?
those numbers are perfect. If you reach your pump limit trust me you will know as it will tell you pump limit reach and you will not get to full throttle.

For or the Xicoy telemetry is depends on the radio. My understanding is that the Xicoy telemetry uses actual voltage to figure out fuel consumption.
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Old 12-16-2015, 02:01 PM
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Ok, that makes me feel better. At least now I know what the normal range should be. Still learning a lot, and I am sure a lot more to learn!

Thanks for the information Jose, I appreciate the information and your knowledge. If it helps I am using a Jeti DS-16 if that helps. Thanks.

Louis
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