Spoonbill Prop

[frank williams]

Does anyone know the history of these props.  Carbon , 10 inch diameter 4 inch pitch and HIGHLY under cambered.
I haven't flown it but I know it makes a great shoe horn.

[Steve Helmick]

They were made in Ozzie by Joe Supercool*, at the suggestion of George Aldrich. At least, that's the story I heard. I don't think many were made, maybe less than a dozen.  Steve

* Can't think of his real name, right this minute. A Google should turn up his website, tho. 

[Brett Buck]

Does anyone know the history of these props.  Carbon , 10 inch diameter 4 inch pitch and HIGHLY under cambered.
I haven't flown it but I know it makes a great shoe horn.

   I think those might be from Joe Supercool AKA Stuart Spurlock from Australia. His website has(had?) a large number of very useful nuggets of information about props.

    They were built at the behest of/direction of/emulation of George Aldrich.

    Brett

[Reptoid]

  I think those might be from Joe Supercool AKA Stuart Spurlock from Australia. His website has(had?) a large number of very useful nuggets of information about props.

    They were built at the behest of/direction of/emulation of George Aldrich.

    Brett

http://www.supercoolprops.com/price_list2.php   Click on first couple of "Stunt" props

[frank williams]

Thanks All
I figured those two might be involved.
Stuart stopped by Houston back in the early 90's and we talked prop theory for a day.
He wrote a neat book about propeller theory and applications to model aircraft.
When I first looked at the prop I said, "Aldrich has to be involved in this somehow".

[Garf]

I had 2 of theese. They didn't show me much.

[RandySmith]

That style of prop would be conducive to larger diameter  very slow moving. They produce whopping drag when turned  at a faster  pace

Randy

[Dan McEntee]

   The late Jim Thomerson had some of these. It's been a while since I saw them run so I can't remember what he had it on but i would assume an OTS model. that was about all he flew up until he passed away. I'm thinking he posted on the forums about them. Jim always did things just a little different from everyone else. I seem to recall he liked the way they performed, but were expensive and hard to get???
   Type at you later,
    Dan McEntee

[Phil Krankowski]

Look just like electric "slow fly" props.  Low RPM makes slow fly props happy, too much RPM and they start to flutter. 

Phil

[FLOYD CARTER]

George Aldrich showed up at the first VSC (Los Angeles) with a home-made wood spoonbill prop on a Nobler.  I don't remember what he said regarding it, but it apparently did OK for him.  The first Y&O props had wide blades to properly load the slower-turning spark engines.  They later were reduced in area.

[Brett Buck]

George Aldrich showed up at the first VSC (Los Angeles) with a home-made wood spoonbill prop on a Nobler.  I don't remember what he said regarding it, but it apparently did OK for him.  The first Y&O props had wide blades to properly load the slower-turning spark engines.  They later were reduced in area.

       Lack of the same prop was asserted to be the reason he couldn't demonstrate 7+ second laps successfully, and crashed. I feel there may have been some other reason for that. 

     Brett

[frank williams]

The Y&O blade airfoil shape is such a horrible shape.  No standard smooth looking curve, blunt and awkward looking.  However, there is a British prop airfoil called the ARA-D which looks amazingly like the Y&O.  The interesting thing is that from the data, its really a pretty good airfoil at prop Reynolds numbers.  Y&O's do work.  This Spoonbill airfoil is just a circular arc, however it is thick enough that the blade is very stiff.  Good Shoehorn.

[Brett Buck]

http://www.supercoolprops.com/price_list2.php   Click on first couple of "Stunt" props

  I know that, I pointed it out above.


    Brett

[Brett Buck]

The Y&O blade airfoil shape is such a horrible shape.  No standard smooth looking curve, blunt and awkward looking.  However, there is a British prop airfoil called the ARA-D which looks amazingly like the Y&O.  The interesting thing is that from the data, its really a pretty good airfoil at prop Reynolds numbers.  Y&O's do work.  This Spoonbill airfoil is just a circular arc, however it is thick enough that the blade is very stiff.  Good Shoehorn.

   All the properly made Y&O and Bull BY&O have an airfoil shape very similar to a typical HLG, and that's very close to what I used to do  for prop rework. It works extremely well in most cases. If you make it with a single pass of the cutter, it has to be an arc, which is why the airfoils for machine-made props all look about the same.

   Part of the problem all along was that to manufacture the props, it took hand operations and some significant skill to achieve. Clarence Bull told me that he had no end of difficulties training various high-school girls to sand it properly, and then about the time they got it right, they would quit and he would have to start over again. That's why they were always in very short supply.

     Brett

[FLOYD CARTER]

I sanded props for Henry Orwick back in my high school days.  Not much sanding required: the complex shaper tooling got it almost right.  My effort was mainly to knock off any rough places, and to then balance the props.

I used an air-filled drum sander, with very fine sandpaper;  didn't remove hardly any wood.

Balancing was also easy;  the sander bench had a 1/4"-undersize horizontal rod. Vibration from the sander motor eliminated friction.

[Steve Helmick]

  I think those might be from Joe Supercool AKA Stuart Spurlock from Australia. His website has(had?) a large number of very useful nuggets of information about props.

    They were built at the behest of/direction of/emulation of George Aldrich.

    Brett

I know that, I pointed it out above.    Steve

[Reptoid]

  I know that, I pointed it out above.


    Brett

Just thought I'd provide a link for those not familiar with supercool

[frank williams]

"Balancing was also easy;  the sander bench had a 1/4"-undersize horizontal rod. Vibration from the sander motor eliminated friction."

Floyd that's interesting ...... Vic Garner once showed me that you didn't need a fancy balancing apparatus .... just put the prop onto a piece of rod (3/32 hex wrench, 1/8 dia rod, etc) hold it horizontal and tap lightly on the end of the rod with a screwdriver.  Like you say, the vibration frees up the friction, and the prop will rotate to the low side.

Brett, where was Clarence Bull located?, I thought out west somewhere.

[Steve Helmick]

Clarence Bull was in Western Oregon. Can't recall right now if it was Eugene or Roseburg, but somewhere in there. As I recall, he found some Vietnamese women to be the best prop sanders. I never found any magic in BY&O 12-5 props, vs. APC 12-5's.  Steve

[Brian Hampton]

I think those might be from Joe Supercool AKA Stuart Spurlock....

Also AKA Stuart Sherlock who gave up his job as a nuclear phycisist to make props.

[Paul Walker]

I can't imagine these props in carbon work well. The gyroscopic effects with all the mass way out on the blade would cause bad yawing issues. Just the opposite of the Igor hollow props.

[Brett Buck]

The real nuggets of gold begin here, by the way:

http://www.supercoolprops.com/articles.php

    Those articles relating to stunt are conveniently labelled "F2B" but I spent hours poking around in the site about 15 years ago and there is goodness everywhere.


    Brett

[Brett Buck]

I can't imagine these props in carbon work well. The gyroscopic effects with all the mass way out on the blade would cause bad yawing issues. Just the opposite of the Igor hollow props.

   I think that in the intended application (Nobler at 7.5 second laps and what I would guess to be no greater than 7000 rpm), precession is going to be the least of your problems!  The fin is airfoiled, offset by about 3/4", and the leadouts are 2 1/2" behind the CG, so I am guessing you aren't going to be too concerned with it yawing in at you.

     Brett

[M Spencer]

Thought they were called ' Petal Blade ' .

[FLOYD CARTER]

Clarence Bull's shop was in Harrisburg, Oregon.  Just a few miles north of my location in Eugene.

I once toured his Y&O "factory", and wrote an article for Stunt News, with photos, on his machinery and procedures.  The shaper for carving props was unique and very clever.  In his yard was a shed piled with some really beautiful logs of maple and beech.

I believe Brodak now makes the Y&O props on CNC machinery.  That is certainly faster than the old way used by Clarence and Henry Orwick.

[Chris Wilson]

I get the impression that they were intended as part of an airspeed regulation plan where a lot of the blades lifting surface is deliberately  ahead of its centre of mechanical strength.
Having the norm of most of the lifting surface aft of where the blade twists will decrease pitch with an increase in speed whereas having most of lifting surface ahead of the axis of twist will conversely increase pitch.

A kind of mechanical speed regulator if you will, and I fully realise that these are rigid carbon props  but they are thin sectioned and have a very high degree of waisting at the root and maybe prone to specifically engineered twisting.

[Target]

Just thought I'd provide a link for those not familiar with supercool

I think that was supercool of you to post the link!

[Brett Buck]

I get the impression that they were intended as part of an airspeed regulation plan where a lot of the blades lifting surface is deliberately  ahead of its centre of mechanical strength.
Having the norm of most of the lifting surface aft of where the blade twists will decrease pitch with an increase in speed whereas having most of lifting surface ahead of the axis of twist will conversely increase pitch.

A kind of mechanical speed regulator if you will, and I fully realise that these are rigid carbon props  but they are thin sectioned and have a very high degree of waisting at the root and maybe prone to specifically engineered twisting.

    I don't think so. I asked GMA about this once, and he said it was intended to reduce the load by essentially ignoring the inner half or so of the blade where it is barely moving and produces negligible benefit, or something along those lines. Whether that works or not, I would leave to experiment. He said that this was necessary to be able to fly as the speeds that he used to fly all the time with great success, 7-7.5 second laps. I would also leave that to experiment, and I would suggest you try it over very long grass with very soft dirt underneath it, and wear track shoes.


    Brett

[Chris Wilson]

In the link provided look up the "Heart of Gold" experimental stunt model for further information.

Stuart seems like to match the models forward speed with the props pitch in the hunt for efficiency - hence 8" of in some cases.
And undoubtedly the 'petal' design was borrowed from free flight where indeed lift forward of the axis of twist does increase pitch with rpm whether intended here or not.