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Prop-pitch; 701 w/Rotax 912ULS

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lgold(at)quantum-associat
Guest

Posted: Wed Jan 02, 2008 9:34 am Post subject: Prop-pitch; 701 w/Rotax 912ULS

I have a  few hours on my new 701 and could use some advice regarding maximum RPM and prop  pitch.  

The prop  manufacturer for my 3-blade Warpdrive suggested a 12-degree pitch. Set at 12-degrees, the maximum  RPM the 701 can develop is  5375-RPM. The plane seems to fly well with this setting. At cruise RPM (4900-5000) is goes  85-90-MPH and at full RPM, lightly loaded, it  will reach the do-not-exceed speed in level flight and climbs  over 1400’/minute. 

I’m  satisfied with the performance but am concerned that I can’t get to the  maximum 5600-5800 RPM that Rotax suggests. Do you think I’m OK with the 5375  maximum RPM, or should I decrease the prop pitch?  

Thanks for the  help, 

Les

   [quote][b]

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larry(at)macsmachine.com
Guest

Posted: Wed Jan 02, 2008 11:25 am Post subject: Prop-pitch; 701 w/Rotax 912ULS

Les,

The inability to get to the highest rpm the engine is capable of is 

probably the wrong approach. You should consider that your performance 

optimized

to an rpm that mixes fuel economy, low engine wear and less noise. I'd 

increase the prop pitch to the lowest rpm that still reaches the 

do-not-exceed

speed and still gives satisfactory climb with a passenger. Sounds like 

you're close, but try 13 and then 14 degrees to see how performance changes.



Larry McFarland 601HDS with 17-degree pitch WD 3-blade 70-inch at 

www.macsmachine.com



Les Goldner wrote:

 	  Quote: 	
		  

 I have a few hours on my new 701 and could use some advice regarding 

 maximum RPM and prop pitch.



 The prop manufacturer for my 3-blade Warpdrive suggested a 12-degree 

 pitch. Set at 12-degrees, the maximum RPM the 701 can develop is 

 5375-RPM. The plane seems to fly well with this setting. At cruise RPM 

 (4900-5000) is goes 85-90-MPH and at full RPM, lightly loaded, it will 

 reach the do-not-exceed speed in level flight and climbs over 

 1400’/minute.



 I’m satisfied with the performance but am concerned that I can’t get 

 to the maximum 5600-5800 RPM that Rotax suggests. Do you think I’m OK 

 with the 5375 maximum RPM, or should I decrease the prop pitch?



 Thanks for the help,



 Les



 *



 *

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alex_01

Joined: 14 Jan 2007
Posts: 33

Posted: Wed Jan 02, 2008 11:43 am Post subject: Re: Prop-pitch; 701 w/Rotax 912ULS

Hi, i fly a 601xl with a 3 blade woodcomp  and i have a very steep setting max take of rpm 4600-4700rpm



climbes with approx 900-1000ft/min  but has a very nice cruising at 110-115 knts IAS  with 4500-4600 rpm and approx 24hg MP



fuel com. approx 15ltr/hour



side effect with less rpm it is also quieter

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NYTerminat(at)aol.com
Guest

Posted: Wed Jan 02, 2008 4:28 pm Post subject: Prop-pitch; 701 w/Rotax 912ULS

Les,

  

 I would reduce the pitch slightly. I am assuming that your max RPM is 5375  in flight right? I would shoot for 5700- 5800 max in flight rpm. You should be  getting approx 5350-5400 static RPM. Right now it seems you are over pitched.  Congratulations on your first few hours of flight.

  

 Bob Spudis

 N701ZX / CH701/ 912S/ 140hrs

  

  

  

 In a message dated 1/2/2008 12:36:08 P.M. Eastern Standard Time,  lgold(at)quantum-associates.com writes:

  	  Quote: 	
		        

I have    a few hours on my new 701 advice regarding maximum RPM and prop pitch.       

The    prop manufacturer for my 3-blade Warpdrive suggested a 12-degree    pitch. Set at 12-degrees, the    maximum RPM the 701 can    develop is 5375-RPM. The plane seems to fly well with this setting. At cruise RPM (4900-5000) is goes    85-90-MPH and at full RPM, lightly loaded, it    will reach the do-not-exceed speed in level flight and climbs    over 1400â€™/minute.   

Iâ€™m    satisfied with the performance but am concerned that I canâ€™t get to the    maximum 5600-5800 RPM that Rotax suggests. Do you think Iâ€™m OK with the 5375    maximum RPM, or should I decrease the prop pitch?    

Thanks for the    help,   

Les

	


 

  



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graeme(at)coletoolcentre.
Guest

Posted: Wed Jan 02, 2008 5:07 pm Post subject: Prop-pitch; 701 w/Rotax 912ULS

My 701 rotax 912

  

 usually two up on acceletation and climb gets 5600rpm a compromise of climb  and cruise 70-75 knots.

 you should try for 5800 on acceleration and climb. 

 then check your other figures.

 NB. two up every thing is much differant speed and climb wise

 you should find in level flight you will over rev if you hold full  throttle.

  

 Graeme cns

 [quote]   ---

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ronlee

Joined: 25 Dec 2006
Posts: 141

Posted: Wed Jan 02, 2008 6:49 pm Post subject: Re: Prop-pitch; 701 w/Rotax 912ULS

I talked to Ronnie Smith, and my understanding is that dragging the engine down too much can cause possible cracking of the crank case. In other words don't pitch the prop so much that the engine can't wind up to near the recommended  RPM on full throttle.

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_________________
Ron Lee
Tucson, Arizona

billmileski

Joined: 07 Aug 2006
Posts: 68
Location: Ledyard, CT

Posted: Thu Jan 03, 2008 6:52 am Post subject: Re: Prop-pitch; 701 w/Rotax 912ULS

Les,

Congrats on the new arrival to the 701 fleet.  My 701 with 912S and 3-blade fixed 68" Woodcomp performs similarly:

Full throttle static rpm: 5250

Climb: solo at sea level on standard day, ~1500fpm

Full throttle in level flight: 110mph (redline) and not sure but I think less than 5500rpm.

Cruise at 4800rpm is around 85mph and 3.4gph (solo). Cruising at 75-80 seems very light load on everything, with even better economy.

That said, I have often wondered about setting static as high as 5400-5500 and see what the short takeoff performance would be, but would expect that cruise rpm would be higher, as well as fuel consumption. Maybe for the next STOL contest.

If you are getting 5375rpm static (or was that your in-flight max?), that sounds appropriate, for more opinion do an archive search, this topic has been discussed.  Cruise at 5000 seems appropriate, personally wouldn't want to spin faster at 85-90. As you fly off the 40hrs (if you have to do a Phase I) you'll find out whether you prefer jump-takeoffs or mellow cruise rpm and increased fuel economy.  Lastly, I think lower pitch (higher rpm) might help reduce glide distance at idle if you desire a short approach as well.

Congrats again,



Bill Mileski

Ledyard, CT

701 912S

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