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Aug 23, 2009, 11:17 AM
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4 or 5 inch diameter folding prop?


Does anyone know of a really small folding prop, like 4 or 5 inches diameter, maybe 2 or 3 inch pitch? I've looked at Hobby City, Dymond, etc., and seen nothing smaller than 6 inch diameter.

I'm putting together a small plane, using one of the 24" span styrofoam chuck gliders and some micro servos, hopefully the all-up weight will be four ounces or so. See https://www.rcgroups.com/forums/show....php?t=1097544 for description and early pictures.

Motor will be one of the 5-gram brushless outrunners from Hobby City. Most customers seem to be reporting good results with props that size (4-5 inch diameter, 2-3 in pitch) for that motor, but they are probably non-folding (I would guess anyway).

The motor also has a shaft that is 1.5mm in diameter, even smaller than the 2.0mm shaft that most small outrunners have. Can that be an additional problem?
Last edited by Little-Acorn; Aug 23, 2009 at 11:25 AM.
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Aug 23, 2009, 11:45 AM
Fully Sending It
Xpress..'s Avatar
Why would you need a folder?
Aug 23, 2009, 01:36 PM
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Quote:
Originally Posted by Xpress..
Why would you need a folder?
Better glide, plus prop protection.
Aug 23, 2009, 02:56 PM
No more nicotine for me!
micro_builder's Avatar
Not quite 4" range, but 3.7x2.3 or 3.7x2.7 here and 3.7x2.3 here too.

Nick
Aug 23, 2009, 07:19 PM
If it flies - I want one!
Petem's Avatar

Graupner?


Graupner make a small folder - 4.5 x 2.7 or similar, I think.
I have one, intended for a small powered glider using the 10gm motor, but can't remember where I bought it.
The other possibility for the 5gm motors would be the K&P (Knight & Pridham) series of folders. These are British, designed for indoor work. They are great for avoiding damage on landing, but I doubt they would fold reliably to reduce drag airborne. They have a range of hubs (2, 3, 4 blade and extended 2 blade; 1mm or 2mm hole) and clip-in blades with two pitch options.
If all else fails, the drag of a fixed prop is quite low, as long as it stops when you close the throttle, and these lightweight aircraft land fairly gently anyway - the little fixed props are also quite cheap (the Graupner ones are not).
All the best with your project.
Cheers,
PeteM
Aug 24, 2009, 07:05 AM
in pursuit of low wing loading
Gordon Johnson's Avatar
Quote:
The other possibility for the 5gm motors would be the K&P (Knight & Pridham) series of folders. These are British, designed for indoor work. They are great for avoiding damage on landing, but I doubt they would fold reliably to reduce drag airborne.
You are correct. I have tested one of the folding K&P props and it does not fold back from the airflow pusing on it. The design is different than the folding props used on sailplanes where there is a pin that allows it to pivot freely. These will only fold back on impact.

Gordon
Jul 21, 2019, 01:40 PM
Registered User
I know this is an old tread, but anybody know off a sub 4" folding propellor for a glider?
Jul 21, 2019, 03:11 PM
Way to much free time!
CorvetteC5's Avatar
Cut down the diameter on the smallest folding prop that you find that fits your motor.....?
Jul 21, 2019, 03:15 PM
Registered User
I just found out that the f959 glider folding prop is supposed to be small at around 104mm tip to tip fully deployed and with 1.5mm shaft.
Perhaps the xk a600 or a800 prop is also small?
Jul 22, 2019, 12:01 AM
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Quote:
Originally Posted by elmar2B
I just found out that the f959 glider folding prop is supposed to be small at around 104mm tip to tip fully deployed and with 1.5mm shaft.
Perhaps the xk a600 or a800 prop is also small?
Yes, the F959 folding prop is 104mm diameter and the shaft is 1.5mm. It is a pusher prop but a close examination shows that you could push the pins that hold the blades on out, reverse the blades, replace the pins and you would have a tractor prop.

The photo shows the F959 and A800 props. The blades are identical. The A800 prop does not have a 1.5mm hole though, as the black hub part pushes onto a brass piece that is a push fit on the shaft.

In summary, I think you could use an F959 prop with the blades reversed as a small folding tractor prop, 104mm (= just over 4 inches), with a 1.5mm hole for the shaft.

You can buy one here.
Jul 22, 2019, 12:58 AM
Registered User
Thanks! Thats great info
Aug 01, 2019, 09:18 AM
Registered User
The E-flite Delta Ray One from Horizon Hobbies has a folding pusher prop. With the removal of a small amount of plastic from the hub, it can be converted to a tractor-style prop. The hub and blades must be purchased separately.
Aug 08, 2019, 09:06 AM
aka: A.Roger Wilfong
gnofliwr's Avatar
Hobby King has some small folders in the 4-5" range. They're pretty good and a pair is only ~$3.50 US. I've used them on some converted HLGs where the prop adapters kept breaking on a hard landing. (pic below).

Here's one...

https://hobbyking.com/en_us/folding-...-5x3-2pcs.html

A search for "folding props" on there web site will find them (along with a bunch of larger ones).

- Roger
Aug 11, 2019, 03:10 AM
Registered User
Thanks for the link and live those little birds!


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