4 BLADED PROPELLORS

[lennyz]

HAS ANYBODY SEEN ANY FUNCTIONAL 4 BLADED PROPELLORS? I DON'T KNOW IF I'M PIPE DREAMING OR NOT, BUT IT SURE WOULD BE COOL TO PUT ON MY SERIES 400 P51

[supercruiser]

I've only seen one 4 bladed prop that was functional. And it was homemade.
Looks very nice and should perform well. MIght try to make one myself but, it looks difficult.
For those that are curious here are the basics of construction:
First you need 4 complete propellers, like the Guillows red 5" prop.
You cut one blade off each of the 4 props.. leaving the other blade and hub together.
This is part you use: the piece that is the whole hub and one blade.
Next you make two identical discs from dense balsa or maybe thin basswood, the size of the back of the spinner.
You draw a big + across the disc. The plus must be centered on the disc.
About halfway out from the center of the disc, drill a small hole at each of the four lines of the +. And drill one hole directly in the center of the +. Drill through both discs at the same time.
(STill with me?) Take one disc, lay it down flat, and insert short piece of wire shaft in each hole. The wire should be slightly longer than the prop hub.(If you use Guillow props, the wire is about .044" diameter or a #56 drill bit.) Glue them in place. NOw slide one prop half over each wire.
Here is the hard part, and I haven't really figured it out yet, you have to carve 4 balsa inserts or spacers between the blades. The spacers must hold each prop directly over the lines you marked on the disc. Also, the spacers must be taller than the prop blades so you have a solid structure to glue the disc to. ONce you have done that, simply place the other disc on top of the prop/disc thing you just made and glue it together. The props and spacers are sandwiched between the discs. Insert your standard prop wire hook through the center of the discs and bend the end over. Cut a small groove in the top disc to give the bent wire something to grab into. Put your spinner over the whole thing.
I cannot take credit for this method, got it from someone over at the SFA Discussion, if i could remember his name , I would like to give him credit for it.

[lennyz]

That does sound complicated and seems like a lot of chances to make an error with alignment. If I have to construct one I was thinking more on the lines of sandwiching two props together with notches in the hubs. This leaves only two angles to get correct-both 90 degrees. Just need to look it over and see if there is enough material to get the blades on the same plane. I'll have to do some experimentation and let you know how it turns out. The Guillow's props can't be too expensive and I should be able to find them locally. Thanks for the idea and if you remember more about where you saw this info, I'd like to see it first hand.
Lenny

[supercruiser]

That sounds like a better idea. Half cut each hub to make a dovetail kind of fit.
Much simpler.

[supercruiser]

I tried that dove-tail method. Have a look at virtualaerodrome. If it's not on the front page, look in my hangar: supercruiser.

[John G. Jedinak]

LennyZ........Go to Virtual Aerodrome and check Supercruiser hanager for a pic. Also, go to your favorite hobby shop on line and check their stock...I know that Masterscrew has 4-bladers, but in fairly large size. If you are not going to fly get a 4-blader and hog it down to size....Luck, JGJ

[kittyfritters]

Supercruiser,

I looked at your 4-blader at virtualaerodrome.com and that's the answer! Brilliantly simple, just a half-lap joint. (Of course, I'm wondering why I didn't think of it. Probably because of all the Comet 3-bladers that I built when I was younger.) I would probably embed some carbon fibers at the side of the hub between the blades for reinforcement. I have repaired plastic prop blades using slow setting C/A (stronger) with carbon fibers across the joint so I know it will hold up even in a severe impact.

If you are really good with a Dremel tool I can see much of the same principle applying to a 3-bladed prop. It would be a little tricky but one blade could hold the front section of the hub, one blade the middle and one blade the back. It probably could use a reinforcing disk of thin plywood or plastic at least at the back of the hub and maybe at the front also, but it seems doable and flyable. Now a 5-blader, (Late WW-2 models) that would be a real challenge!

Howard

[Geoffrito]

I've seen a few three bladed props on this page http://ffscale.co.uk/.

Browse around, but I'm pretty sure he's just cemented three prop blades onto a hard balsa disc with a spinner over the top

[supercruiser]

I was just looking at Shorty's Basement, a free flight model supplier. They have 3 and 4 bladed props. And I went through all that trouble of making one.

[John G. Jedinak]

Supercruiser.......Interesting...just tried WITHOUT success to bring up Sorty's Basement. It says error..no can do...????

[John G. Jedinak]

I did enter it correctly as SHORTY'S BASEMENT. Foregoing was a typo....sorry....JGJ

[supercruiser]

www.shortysbasement.com

[John G. Jedinak]

Supercruiser..............Thanks. I was able to establish a link this time.JGJ

[uniondude]

These Props props look very scale on the 400 series warbirds...scroll to the bottom of page to find 3-4 blade props. Nice price too. Now if I could only find some for the 500 series...anyone, anyone...



http://www.hobby-lobby.com/slowprop.htm

[uniondude]

This link will take you to a couple of pictures of 400 series warbirds with the props I had mentioned earlier.



http://www.rcgroups.com/forums/showthread.php?t=253265