VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.

  #11  
Old 10-24-2020, 09:09 PM
Cumulo Cumulo is offline
 
Join Date: Apr 2015
Location: KHMT
Posts: 62
Default Van's comment, etc

Some really good comments re fixed pitch, particularly Mr. Van G's on the front page with Propman and others in the thread.

I have used Javaprop to do light a/c prop design simulations for many years as a hobby. Van's analysis is totally in sync with some of the results I have produced with Javaprop. The program has shown that a prop design similar to the one in question will be maybe 70 or 80 percent stalled at static. This will reduce loading and static thrust as well as increase static RPM. I have also seen design examples of a prop loading up with increasing forward speed and a subsequent small drop in RPM as speed increases, just as in a previous comment by dart11. So its nice to know that the wiggly lines produced in Javaprop can be real in the real world.

Once upon a time, more than half a century ago, I competed in model a/c speed contests. Making the blades thinner than stock would = faster up a point, then a further thinning would result in a drastic loss of speed. Propeller flutter may be more common than is thought.

A very flexible prop is bound to flutter at some point with an increase in flex or speed if special attention is not given to increasing torsional stiffness or forward load the section CG. It is SOP with helicopter rotor blades to weight the leading edge, for example. For light a/c wood props, metal edging can help serve this function. So, yes, Propman keyed in on flutter. He may have something for you.

Ron
Reply With Quote
  #12  
Old 10-25-2020, 09:50 AM
DeltaRomeo DeltaRomeo is online now
unfluencer
 
Join Date: Jan 2005
Location: Highland Village, TX
Posts: 4,103
Default Dick VanGrunsven input....

Dick V. saw this thread and emailed me the following to add:

v/r,dr
__________________
Doug Reeves (your host)
  • Full time: VansAirForce.net since '07 (started it in '96).
  • Part time: Supporting Crew Member CAE Embraer Phenom 300 (E55P) @ KDFW.
  • Every Now and Then: Contract pilot (resume).
Reply With Quote
  #13  
Old 10-26-2020, 12:01 AM
springer springer is offline
 
Join Date: May 2012
Location: AZ/MN
Posts: 381
Default

Warnke "Almost Constant Speed" was pretty much in name only. Prior to those his standard props had a wider chord and performed very well. I had one on my O-360 RV-4. Similar props today are made by Performance Propeller which was first owned by Warnke's ex son-in-law who copied his design.

Warnke was always experimenting with new designs, ie the "Toothpick." My hangar was next to his and I tested many but none ever surpassed his original wider chord "Club" as I would tease him.

Bernie was a great guy....hard to believe that was 30+ years ago.
__________________
Jim
RV-4 '88-'09 Built & Sold
RV-8 Purchased
Reply With Quote
  #14  
Old 10-27-2020, 11:01 AM
flyboykelly's Avatar
flyboykelly flyboykelly is offline
 
Join Date: Jun 2006
Location: Port Orange, FL (7FL6)
Posts: 276
Default GT Propellers

I'd give GT propellers a close look. I use one of their props on my radial RV and love it. They worked with me to engineer a blade for my specific installation. They also make replacement blades for a hartzell hub. In fact they have a blade that is modeled after the spitfire blade.
__________________
Flying as of 1-12-2016!!!!!
Reply With Quote
  #15  
Old 10-29-2020, 01:31 PM
Kent Ashton Kent Ashton is offline
 
Join Date: May 2010
Location: Concord, NC
Posts: 122
Default

Your prop tips are still pretty wide. I had a Performance Prop giving me about the same RPM you discussed. I drew a line along the leading edge and cut down the tips thinner, worked the wood to match the existing profile, rebalanced it, also glassed it but that was just to make sure it was stiff enough. Pics are before and during the glass application. It gave me about 125 more RPM. (the dots are lead shot to balance it)
Attached Thumbnails
Click image for larger version

Name:	IMG_0003 copy.jpg
Views:	46
Size:	493.1 KB
ID:	3998  
Attached Images
 
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 07:03 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.