Need advice - in flight adjustable prop

by John Fleming in 912 / 914 Technical Questions 6 years ago

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Re: Need advice - in flight adjustable prop

by John Fleming » 6 years ago

John Fleming

15 92 111

UPDATE.

So for those still tuned in at home, I had a perfect morning for a fly today and so took the Sporty up and really put the AP through it's paces.

I hit WOT and prop coursed up to get her sitting nicely between 5300 and 5500 and we smashed along at 120GS (about 105 indicated)

We were at about 590kg, so almost full weight, and she just cruised nicely. MAP sat around 25.

Pretty happy with all of that, and fuel burn calculated to be right on about 20L an hour.

Cheers
J

Thank you said by: RotaxOwner Admin

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Re: Need advice - in flight adjustable prop

by Neil Cooper » 6 years ago

Neil Cooper

23 67 92

I use the table below for my CSU. It’s conservative and stays within the limits. Generally I cruise at 5350 WOT above 3500’DA and below that 5350 at the below MAP

2A2A9DE8-85EC-49D1-A121-A253A3AE4DB9.png (You do not have access to download this file.)

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Re: Need advice - in flight adjustable prop

by Roger Lee » 6 years ago

Roger Lee

125 5.12k 4.53k

Okay guys so here's my question.
What is the difference if you set your CS or variable speed prop to only get 5350 at WOT or over pitching a ground adjustable prop to get 5350 at WOT? Are they not both over pitched? Which has no redeeming qualities?

/

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: Need advice - in flight adjustable prop

by Glenn Martin » 6 years ago

Glenn Martin

3 281 799

Hi Roger,
you are correct no difference that I can see. However the graph and story says he was at WOT .....but only a MAP of 25 which seems a little low perhaps his DA was high or he has restrictions on the inlet. 25 MAP 5350 rpm is only about 70% power and should be fine. However 5350 rpm 29 MAP would not be a good place to cruise both for torque reasons and because you will be very high fuel burn and therefore would be "over proped" but not over proped if MAP is 25. I have found that with a CS prop the settings should be based on MAP and RPM and where the throttle is at is less important as DA has a huge influence on throttle position. The CS prop allows you more options

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Re: Need advice - in flight adjustable prop

by Capt. Siva, » 5 years ago

Capt. Siva,

25 266 738

Hi Bill,
i appreciat your knowledge on above threads.
i am also in same problem on 914 F2.my propeller is variable pitch installed.
115% throttle, Rpm goes overshoot 5900 + with AIRBOX 42 INCH/1400 hPa approx, all other parameter Okky.
How i identify the problem?
variable pitch propeller or Engie 914F2 /F3/F4 configuration.

Screenshot_2018-12-05-04-04-27-028_com.manualslib.app.png (You do not have access to download this file.)

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Need advice - in flight adjustable prop

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