Prop mod photos - Noblarf follow on

LAST EDITED ON Jan-05-04 AT 04:08 PM (CDT)
 
Here are the photos of what I do to props as mentioned in the Noblarf thread. There is about 1/64" of undercamber at the widest part of the blade. The leading edge is quite smoothly rounded, no sharp edge.

Before I scrolled down and saw it really was a Rev-up, thought you were reworking Zingers to look like Rev-up's

>Before I scrolled down and saw it really was a Rev-up,
>thought you were reworking Zingers to look like Rev-up's

Yes, I'm sure they are Zingers, reworked to look like Rev-Ups, just as advertised. Larry, how did you stamp "Rev-Up" on the blade, tho? I can't get a Rev-Up through the scanner. Steve

Star Trek replicator, that's how! A good thing, working near Hollywood and having a kid working in the movie industry.

Hi DesignMan, thanks for the pics, its easier to visualize something when there is something to visualize . So, after this rework you perform, do you have any vibration problems from creating uneven "lift" between the prop blades? How do you insure you have maintained a symetrical or indentical airfoil on both blades? I read how you marked out the prop stations, but how do you measure the depth of cut? Have you measured any thrust gain from doing this mod? I only ask, because this sounds like something I would like to do. Also, do you have a mini prop "workbench" for doing your work? Excellent subject, downright cool........

LAST EDITED ON Jan-06-04 AT 09:34 PM (CDT)
 
Larry,

What are the effects of your modifications?

As long as the prop is weight balanced, and I balance on a Top Flite magnetic rig with an all-metal prop support (sold by Great Planes, I think for finger balancing). I balance in both directions so the prop will stop anywhere, not just level. I have had no vibration problems. (The Top Flite prop support is pretty cheesy, and out of balance itself!)

I use a caliper to match the blade thicknesses at every station, and with eyeball smoothing of the airfoil as mentioned in the other thread, there has been no problem.

I have not run any formal tests on the props, but Keith, Jim Armour, and I have all been pleased with how planes fly with them.

No special place or equipmentrequired, in fact, I usually whittle them out at lunch on my drawing board at work. I only do the final balance and finish at home, because that is where the balancer is.

DesignMan, you make it sound too easy. Do you have a backround carving your own props? You got my intrest going with that little blurb on the other post. I have been sorta thinking about this kind of tinkering in the back of my mind for a while. I am mostly interested in eliminating engine vibration. Taking the prop out of the equation seems like a good place to start, but gaining a more efficient prop in return is a bonus. I feel like giving my own props a try now, thanks for the answers to my many questions.

No special skills required. I do like to use the PermaGrit rasps from Micro-mark (and elsewhere). I finish with just about anybody's Clear Urethane spray, 2 coats with light sanding (400 grit) between.

I only ever carved one prop from scratch in my life, and that was 40 years ago or more.

PS. A bad airfoil is probably 95% as good as a good airfoil. But, who wants to give up 5% if you are flying competition. Good airfoils have higher lift to drag ratios, better stall characteristics, and higher ultimate lift. Not a bad combo!