Ed,
  I did the same calculations at:

 http://www.culverprops.com/pitchselection.htm

I do believe there is a typo, I would not have caught it if everyone on the forum did not catch it.  I appreciate the input from everyone.  I currently have tunnel vision with attempting to get the engine to idle correctly.  I am going to try to run the engine on the secondaries to see if it runs correctly per the recommendation of Tracy. 

On Sun, Sep 4, 2011 at 9:39 AM, Ed Anderson <eanderson@carolina.rr.com> wrote:

According to an on-line prop tip speed calculator at 70F, you can spin the 76 " dia prop at 2550 rpm and have a tip speed of around mach 0.75 which still keeps it a bit on the low side of the desirable range for tip speed (0.88 - 0.92Mach).  However, there could be other reasons for the restriction as has been mentionded such as structure limits, tip flutter, prop track disc, etc.

 

Ed

From: coastiefamily4

Sent: Sunday, September 04, 2011 11:24 AM

To: Rotary motors in aircraft

Subject: [FlyRotary] Re: 20B Tuning

I think there must be a typo in the manual, I rechecked it this morning and is reads 2150RPM.  Instead of 2150 RPMs on the prop I am thinking it should be 2550RPMs for a 76inch prop for a tip speed limit of 850fps equating to 7250 engine RPMs.  I will call the manufacture on Tuesday to verify my calculations. 

I appreciate everyone's comments.

On Sun, Sep 4, 2011 at 8:07 AM, Charlie England <ceengland@bellsouth.net> wrote:

Wow. How big is it?

On 09/03/2011 10:50 PM, coastiefamily4 wrote:

Tip speed

On Sat, Sep 3, 2011 at 9:18 PM, Kelly Troyer <keltro@att.net> wrote:

Is the rpm limit because of diameter (tip speed) or a structural blade limitation ?..............

 

Kelly Troyer
"DYKE DELTA JD2" (Eventually)

"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold

"TURBONETICS"_TO4E50 Turbo

From: coastiefamily4 <coastiefamily4@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

Sent: Saturday, September 3, 2011 6:06 PM
Subject: [FlyRotary] Re: 20B Tuning

The prop is adjustable, it is hydraulically controlled.  I current have it set to the fine pitch setting.

On Sat, Sep 3, 2011 at 4:51 PM, Bobby J. Hughes <bhughes@qnsi.net> wrote:

If it's adjustable you may need more pitch. A 2150 rpm limit seem very low.    Bobby

Sent from my iPad

On Sep 3, 2011, at 5:57 PM, "coastiefamily4" <coastiefamily4@gmail.com> wrote:

This is not full throttle, I have to stop at 6000 RPMs do to the 2150 RPM limit on my prop. I am using a VARI PROP, it is great so far.   I have plenty of throttle, just prop limited.

On Sat, Sep 3, 2011 at 3:44 PM, William Wilson <fluffysheap@gmail.com> wrote:

23.3 is just about exactly what would be expected.

Perhaps the throttle is not opening all the way?  You would have to have a pretty convoluted intake to lose 3" of pressure in it.

On Sat, Sep 3, 2011 at 3:40 PM, <bktrub@aol.com> wrote:

At what density altitude was that measured? Maybe your MAP needs to be calibrated.

 

Brian Trubee

-----Original Message-----
From: coastiefamily4 <coastiefamily4@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, Sep 3, 2011 1:50 pm
Subject: [FlyRotary] 20B Tuning

My static MAP before starting the engine was 23.3