Propeller static run up.

[trailer]

I am curious to know if a direct drive prop will increase rpm as it starts moving forward or if maximum rpm is achieved while the aircraft is chocked?

 

I have never done a static full power run.

[Yenn]

It depends upon the pitch of the prop. Most props are pitched to provide a satisfactory rate of climb, plus high speed. If the prop is pitched finer it will achieve higher revs before moving.

[facthunter]

Can you explain why that would be so?  Nev

[Thruster88]

1 hour ago, trailer said:

I am curious to know if a direct drive prop will increase rpm as it starts moving forward or if maximum rpm is achieved while the aircraft is chocked?

 

I have never done a static full power run.

All fixed pitch propellers will increase in rpm as speed rises. 

 

Static rpm will be found in all certified aircraft Pilot Operating Handbooks, POH or flight manual. It is a sure fire way to know the health of the engine, not making static rpm, something is wrong. An interesting thing is static rpm is not dependent on altitude, or density altitude. With increasing density altitude the propeller becomes easier to turn at the same rate the engines ability to turn it decreases. 

 

For the Beech 23, 160hp fixed pitch static is about 2300rpm, in climb at 78knots about 2500rpm, straight and level full throttle about 2700 rpm which is the red line. Normal cruise at 75% about 2450rpm.

[facthunter]

A static run for a warmed up engine does no harm and is a good check of the thrust you can expect from the engine. It's useless with a  C/S (governed ) Prop. You can use it to good purpose where the runway borders on being length limited. Full power on the brakes and release them quickly.. Nev

[old man emu]

1 hour ago, facthunter said:

Full power on the brakes and release them quickly.

Is short field take-off technique taught nowadays?

[skippydiesel]

9 minutes ago, old man emu said:

Is short field take-off technique taught nowadays?

I would hope that all pilots understand the techniques of STOL. The landing part may just save their life one day. Only practice practice will achieve a credible performance for your aircraft.

[skippydiesel]

As for Static RPM - I followed the Rotax recommendations (5200 rpm @ WOT), for my last air craft, fitted with a ground adjustable prop. 

 

This gave very short ground role and great climb. The climb RPM @WOT must be managed to prevent overspeed (yes the engine speed increase with the aircraft speed) by using climb angle - lower the nose and RPM rises, raise and it slows.

 

 

[spacesailor]

Different from my senior instructor! .

" your take off was too fast " .

I wonder if losing weight is a good thing while training  ? .

spacesailor

[Thruster88]

21 hours ago, skippydiesel said:

As for Static RPM - I followed the Rotax recommendations (5200 rpm @ WOT), for my last air craft, fitted with a ground adjustable prop. 

 

This gave very short ground role and great climb. The climb RPM @WOT must be managed to prevent overspeed (yes the engine speed increase with the aircraft speed) by using climb angle - lower the nose and RPM rises, raise and it slows.

 

 

Setting static rpm with a fixed pitch propeller also needs  to consider the max cruise for the aircraft. I believe Van's RV aircraft with the same 0-320 lycoming as my slow beech 23 will only achieve about 2000rpm static versus 2300 for the beech. 100 v 150 knot cruise.  

[Geoff_H]

I have roughly sketched the mathematical reason for engine speeding up as aircraft moves forward.  Sorry it is so rough but somewhat busy at present.  In summary, as the aircraft moves forward angle of incidence of prop blade to air gets smaller, thus the drag on the prop gets smaller so the engine speed will increase

[facthunter]

Same as overspeeding the engine in a dive. Airspeed affects a fixed Pitch prop always.  AT higher speeds the air will be driving the engine. The energy for that is from height loss.  Nev