control snakes and prop size !!!

[john melia 1]

been busy installing control snakes in my force one delta wing , the ones i ordered have a solid core like this ...................

my question is what do i put on the end of it ? i cant get my snap links to screw on , and i've notoced at the other end it has a metal extension shaft crimped on and a snap link screwed onto that , where can i get these extensions so i can do the same with the end in the photo ?

Also while i'm here , i'm going to put an asp 52 on the back (its a pusher) of the force one , the recommended prop size for this engine going off asp's chart is 10x6 , but as can be sen in this photo .............

the prop aperture is only 10 inches , could i put a smaller prop on , and what would be the difference ?

[ben goodfellow 1]

use m2 or m3 solder extenders but just crimp them on

[John Privett]

I suppose the obvious answer is to use a 9x7. If it's a fast model then the higher pitch prop will probably suit it better than the 10x6. Alternatively how about a 9x6 three-bladed prop? Though if the model doesn't have an undercarriage (does it?) then a three-blader may be rather more vulnerable when landing. BTW, operating through a slot like that, I wouldn't anticipate it being a quiet model...

[john melia 1]

it does have undercarriage , and where i fly noise isn't a problem why would it be louder operating through a slot , as opposed to being bolted on the front end in the open ?

[John Privett]

Not sure exactly why it is, but it's to do with the interactions between airflows. Pusher models (like a Zagi) where the prop is very close to the trailing edge are usually noisy too. Let us know what it sounds like when you fly it.

[john melia 1]

will do john , what would the difference be between the two and three bladed prop , the photo on the box shows the force one with a three bladed prop

[Shaunie]

I believe the noise is due to the "near field effect" I think the prop blade is chopping up the air streams coming off the wing a bit like a siren really.

Shaunie.

[John Privett]

A three-bladed prop will be a little less efficient than the "equivalent" 2 bladed-prop. And as it has an extra blade it has to be a bit smaller to keep the load on the engine roughly the same as with a 2-bladed prop. So the usual rule-of-thumb is to go down an inch in diameter (for "typical" sizes of props) if using a 3-blade, but keep the pitch the same.

In the full-size world three (or more) bladed props get used when the size of 2-bladed prop that would be required becomes impractical (eg. due to ground clearance) So look at the prototype Spitfire. That had a 2-bladed prop - though admittedly a rather huge-looking one. Production Spitfires had 3-bladed props initially. As power outputs increased over the years bigger and bigger props were needed to convert the power from the engine into thrust and to keep the size manageable 4-bladed and ultimately 5-bladed props were used.

[john melia 1]

thanks john , i'm like a big old sponge at the moment soaking all this information up , i love it