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Re Propellers

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propellerdesign(at)tele2.
Guest

Posted: Tue Oct 24, 2006 12:09 pm Post subject: Re Propellers

The right place is 75% radii from center of hub to  tip, or 25% from tip, if diameter is 68" that is 8,5" from the tip or 25,5" from  center.

  

 when an total change of half degree+ make a  difference from a standard prop to an cruise prop, 2 degree at the tip  make some difference if it is only at the tip.

  

 But as Dave measured, and difference of half deg  make a lot difference on a whole blade.

  

 is #1 = 47,75" pitch

    #2 = 48,58" pitch

    #3 = 49,40" pitch

  

 I got 47,89" on a Standard and 49,64 on a Cruise  prop in my program at 75%

  

 Jan

  

 Dave said<

 >all 3 blades are same  degrees on tip    (  about  10,5 degrees) but the 

measurements at this   station    is about .82 the length of prop. Not 

ideal but I  used what I had....

blade 1      15.25 deg

blade  2      15.50+ deg

blade  3      15.75 to 16 approx.< 



    [quote][b]

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Tue Oct 24, 2006 1:08 pm Post subject: Re Propellers

Ok ,   Just went out to shop and got more  accurate measurements.

  

 Here are the three measurements that I took as  follows.

   

                               Distance from centre of hub     

                    25            25.5       at tip 34 1/8 inch

 Blade 1         15.25         15.75              -10  (light 10 degree)

 Blade  2        15.50        16.50               10 

 Blade 3         16              16.75            +10   ( heavy 10 degree) 

  

 as it turns out  the 25 Inch from centre was  my original measuring point  no  .82 of the  length - my  mistake.

 My conclusions  -well I know it flys well  now as you see it set above and wx sucks today for accurate measurements   15 gusting 24 in light rain and snow showers   so I wait for another  day.

 but I think maybe set all three blades at the 25.5  inch place to about 16.25 to 16.5 degrees...  how does this sound >  ?    And the tip ?  Well  we worry about that later I  guess. 

  

  

  

 Dave

  

  

 [quote]   ---

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Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Oct 24, 2006 4:30 pm Post subject: Re Propellers

To be clear  ..

  

 What you are saying is the  folks at Warp are wrong and the blades pitch angle should be set at and all  equal at .75 the length of the blades.

  

 

Noel [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Tue Oct 24, 2006 5:46 pm Post subject: Re Propellers

Ok, I just put together new GSC  68 " blade  tonight and  did preliminary pitch setup on  shop table. 

 Set at 16 degrees to start and that is measured  with GSC protractor and it fits snug at 23.75 inches from centre of hub.  

 in my calculation that comes out to 69.9 %   radii.

 Measuring at tip gives about the same 13 degrees on  each blade approx. 

 Wx permitting I will re adjust WARP and test fly  and try GSC as well. 

  

 I do have a 70 or 72 inch IVO UL prop  2 blade  that I have used on same Kitfox with 3 to 1 box but IVO does not recommend it.  on a 2.68 it supposed to be fine. The Blades are brand new and I only tested for  an hour or so.

 It is for sale if anyone wants it or if IVO is  reading this I will trade you for a suitable prop to test and publish the  numbers. They say a Medium is a better fit for a  582 3 to 1 box. 

 Same goes for any prop manufacturer, send me a prop  and I will try and video and publish the numbers.  If you got it -, might  as well flaunt it.  Repeat business is best from word of mouth and  practical testing.

  

  

 Dave 

  

  

 [quote]   ---

propellerdesign(at)tele2.
Guest

Posted: Wed Oct 25, 2006 4:40 am Post subject: Re Propellers

I am saying that if the blades is made uniform with  each other you can use any reference point to make them equal  pitch.

  

 If they are like it seems not uniform, 70 - 75 %  radii is best.

 Why? this is not only the center of thrust but also  the peak of thrust, differences here make a bigger difference then at the  tip or near the hub.

  

 from 60 to 90 % the thrust is high, from 90% to tip  it is reduced, and from 60% to 15% it is also reduced to zero.

  

 To compare different props the 75% station is best,  due to different twist between different brands.

  

 Jan

 [quote]   ---

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Oct 25, 2006 9:06 am Post subject: Re Propellers

So Warp is at fault here for  producing at least six blades the are not consistent.

  

 Thanks..... I bought an  Ivo-ul primarily because of the in cockpit adjustable feature ( floats )  but when I contacted Warp it was going to take weeks before any blade ordered  would be shipped. 

  

 The Ivo has its idiosyncrasies  too.  they require that you check the torque on the mounting bolts at  regular intervals...  They are so adamant about this that they don't put  holes for lock wire in the heads of the bolts because they say people don't want  to cut a little lock wire to check the prop torque.  

  

 I think the Ivo does a bit of  coneing but that is away from the cowl.  I do know it's a lot smoother than  the time expired GSC it replaced.  I would consider going back to GSC with  the cockpit adjustable two blade hub with the nickel edge Warp blades if it  would fit on my Rotax "B" box PSRU.  (it won't)  Now I'm not sure  about the Warp blades.

  

  

 

Noel [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

dosmythe(at)cox.net
Guest

Posted: Wed Oct 25, 2006 9:41 am Post subject: Re Propellers

Noel,

     I started this thread about the  tips of the Warp blade.  Actually, I first reported it over 5 years  ago and nobody ever came back with a check of their own.  First off, even  if it's a true situation that doesn't make it a bad prop.  You noticed I  said "IF".  The beauty of this List is the ability to see what's going on  in the Kitfox world.  We have uncovered many problems in the last 10 years  or so.  Some were very minor and some a whole lot bigger.  I have a  strong feeling this tip thing is a minor problem.   In the ideal  world, all list members owning a Warp would go to the airport on a lazy day and  map out their props and report back.  If it turns out that many see the  same situation then we would have leverage to go to Warp and report our  findings.  They might just have to relax their opinion on measuring at the  tips.  

     Bottom line, I don't think Warp  is at fault for making bad blades.  I do feel strongly that measuring at  the tips is not the best way to go.  Lets face it, measuring at the 75%  point can't be a safety or dangerous method and as pointed out on this thread,  the 75% point is the hardest working point.

     

 Don Smythe

  

  

   ---

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Wed Oct 25, 2006 4:17 pm Post subject: Re Propellers

Don, pretty well  said  there.    I did change all three of mine after a flight at  dawn.

  I set hem all at the .75   mark   25.5" from center of hub.   One tip was out about 1  degree.

  

 To be honest I really  don't think that I  found any differnances and if anything perhaps a little less  vibration.

 I did not have a chance to get again till about  noon and winds were 10 g 15 knots on ground and kinda bumpy and hard to get  good numbers. 

 I finally got out again at about 4:30 til  5:30  temp  39F  winds on ground 7 knots and at 3000  asl  ( 2000 agl) about 20 knots 

 I did climbs and still remains 1200 to 1400 fpm  ,cruise about 88 to 90 mph   (at)  5900 rpm  and fuel flo about  19 to 20 litres / hour. 

  

 I have a GSC  here 68" as well and will   try it as soon as I can this week hopefully and report back.

  

 Dave



 [quote]   ---

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Wed Oct 25, 2006 4:31 pm Post subject: Re Propellers

Warp blades ok in my book. 

 Warp blades are probably too heavy for a B  box.  You should get a C or E box  with rubber damper for  smoother operation as well.  E box would be my choice. 

 2 blade props should not be used on 582 with 3 to 1  ratio.  Not sure exact reason but might be some resonance or something that  causes extra strain and stresses and will possibly lead to failure. I don't  think Warp or IVO recommend this.   IVO  will allow a medium  prop on a 3 to 1 box  because of it's larger size hub over 5 " whereas the  smaller one is about 4 inches. 

  

  

 Dave

  

  

 PS Warp Blades take about 2 to 3 weeks to get , GSC  a week and IVOs overnight.   WARPs with nickel leading edge is most  abrasion resistant for dirt, sand, stone and float operations

  

 [quote]   ---

dosmythe(at)cox.net
Guest

Posted: Thu Oct 26, 2006 3:24 am Post subject: Re Propellers

Dave,

     That's either good or bad  depends on how you look at it.  At least, a point is starting to get made  that the tips are suspicious.  If you had pitched at the tips you would  have had that 1 degree error at the .75 station.  Maybe I'll go back to  Warp and see what they say now.  I think that is 3 or 4 of us that see a  little error.  I lost track.

  

 Don Smythe

 [quote]   ---

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Thu Oct 26, 2006 3:47 am Post subject: Re Propellers

Yes Don,   

  

 So I will trry to get some more accurate testing  done and  see.   Now it would be interesting to see what Warp has  to say and the reasoning for their approach to adjusting at the tip.  

 Maybe WARP thinks their blades are 100 % uniform  from root to tip.   Once thing I  did not check was the tracking,  although I should have .    I will go out to shop now and look  and let you know soon.

  

 Also as you can see from the movies we did last  Weekend from the Trailer park   <snicker>  http://www.cfisher.com/kitfox/    this Kitfox is not lacking in short  field performance  in my opinion.  So what does that say about the Warp prop  that seem to not be uniform  ?   Any comments on a better way to test ?

  

 Dave 

  

  

 [quote]   ---

dosmythe(at)cox.net
Guest

Posted: Thu Oct 26, 2006 4:21 am Post subject: Re Propellers

Dave,

 See below

  

 >> Maybe  WARP thinks their blades are 100 % uniform from root to  tip.>>

  

 I think that Warp chose the tips because it's a  reference point for them.  They want to know what pitch you have for a  particular plane/engine when they provide service.  If everybody uses the  same point (tips) they have a good reference base.  It doesn't do them much  good to have a customer give them a pitch of 27 degrees and another give  them 15 degrees for the same plane/engine setup.  Maybe, just maybe they  don't really realize that their tips "could" be off just a tad????

  

 >>that say about the Warp prop  that  seem to not be uniform ?>>

  

 Again, I think the blades are very uniform (in my  case anyway) all the way except the last 2".  I think this is a very minor  situation but worth knowing about.  When we adjust our props, we want to be  exact as possible.  Right????

  

 Don Smythe

  

    [quote][b]

propellerdesign(at)tele2.
Guest

Posted: Thu Oct 26, 2006 4:27 am Post subject: Re Propellers

Dave, 

  

 Why not call Stuart at Powerfin and ask if you can  borrow a 68" 3 bladed F-blade prop for testing?

  

 Phone <?xml:namespace prefix =  st1 ns = "urn:schemas-microsoft-com:office:smarttags" />1 (509)  924-7556  - Toll  Free 1 (800)  581-8207

  

 Jan

 [quote]   ---

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Thu Oct 26, 2006 4:40 am Post subject: Re Propellers

I agree with every thing  you have said here.... And I will usually find something to disagree with,  so this is a to me an event. 

  

 I still find it amazing with  this information, apparently reported to Warp several times, they haven't  changed their manuals to designate the .75 station as the place to measure prop  angles.

  

 I would also like to  strobe a Warp prop at Take off speed.  I'm willing to bet dollars to  doughnuts that there is some flexing going on as centripetal forces  increase.  Blade flex to decrease pitch with rpm, as I understand it,  occurs in the Boer prop used on SuperCub sea planes.

  

  

 

Noel [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Thu Oct 26, 2006 4:47 am Post subject: Re Propellers

OK , just went out again and measured  prop   -- all 3 blades at 25.5 inches from centre of hub at 16  degrees

 Measured at tip as follows    10 ,  10.125  10.875   

 tracking of all three  measured at tip   within  .125 inch at most  more like about 3/32s

  

 Went for flight temp 37 F   air dead calm  every direction at under 200 agl   flew 88 70  89.5 mph  via  gps in any direction at low altitude.

 Did this for 20 mins.  Very pretty when you  see every chimney and smoke stack with a vertical column  of smoke   going steady - straight up ........

  

 Prop works well ,  GSC going to get tested  next  - hopefully today  !! 

  

 Dave 

  

 [quote]   ---

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Thu Oct 26, 2006 4:48 am Post subject: Re Propellers

If you know him have him email me  .....   I would be more than happy to compare his best choice to the  others.

  

 Dave 

  

  

 [quote]   ---

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Thu Oct 26, 2006 5:31 am Post subject: Re Propellers

Noel it a Borer prop and they are a must  have for a  super cub on floats.

  

 Same goes for Kitfox -  We need a ultimate  search for the best prop for Kitfoxes. 

 I sure the 582 as I have one and they are probably  the most intalled engine in Kitfoxes. 

  

 Prop manufacturers should be happy to show off  their product.  I am not looking for handouts but I have paid for every  other prop I have. 

 If anyone wants it tested  "un- biased"   well let me know .

  

 Dave 

  

 PS  can we geta Borer prop for a Kitfox  ?  

 [quote]   ---

lcfitt(at)sbcglobal.net
Guest

Posted: Thu Oct 26, 2006 5:57 am Post subject: Re Propellers

Jan,



Not familiar with the term F-blade.  Is that new to Powerfin?



I fly regularly with a group that does long cross countrys together and lots 

of high altitude and short field stuff in the back country of Idaho.  Two of 

the guys switched to Powerfin propellers about 3 or four years ago.  One 

switched from a GSC wood, and one from a Warp - pitched at the 75% station 

incicentally.



Both guys had reduced cruise with the powerfin and this was determined by 

the overall pace of the flight of six guys over three or so years of flying 

in loose formation together.  Pitching for optimum cruise and climb was a 

challenge.  The Powerfin climbed very well, but at the expense of top end 

and the top end never equalled what they had before.  I always liked it when 

they were on their Powerfin props because I could wander off to see 

something of interest and always had the top end to easily catch up.  Not so 

easy now - one went back to his GSC and now has the IVO and the other is 

back to the Warp.



I have been flying behind a Warp 70 inch three blade and could always stay 

in reasonably close performance range with the Powerfin in climb and miles 

ahead in cruise. My Model IV is heavy - 700 lbs - but is very clean with 

lots of fairings.



Lowell

---

propellerdesign(at)tele2.
Guest

Posted: Thu Oct 26, 2006 6:53 am Post subject: Re Propellers

Hi

  

 The model F is there largest blade, recommended to  be 68" 3 blade on the 582 3:1 

  

 Interesting, I would have bet that it was faster  but not did climb as good as the Warp.

  

 I think the Powerfin use Clark Y airfoil, and the  Warp have RAF6 style. GSC I don't know.

  

 the difference is that RAF has the nose radii  starting from the flat bottom, Clark Y the nose radii is higher up.

  

 RAF have better take off performance then Clark,  but Clark have higher efficiency.

  

 But it all depends on blade twist, thickness, blade  area ...

  

 Do you know if they used same diameter on the  Powerfin as the other and what blade model it was?

  

 Jan

  

 Ps. I have no business with any propeller maker,  just interested to get the best out of it.

 [quote]   ---

lcfitt(at)sbcglobal.net
Guest

Posted: Thu Oct 26, 2006 8:09 am Post subject: Re Propellers

Jan,



I went to the Powerfin site and think they were using the F blade.  To 

improve performance a bit, they cut some off the end of the prop.  I don't 

know how much but an inch comes to mind.



Lowell



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