Servos in a Prangster

[Tim Morton]

Appreciate some guidance on installing servos in a Prangster and apologies in advance for stupid questions....

 

To be fair the build notes are a little short in detail .... or maybe I'm just being dumb and can't see the assembly!

 

The instructions show a small photo of the radio system with the servos and actuating arms (assumedly cut off to suit).  It describes the installation of servos in various premoulded slots in the fus. and wing 

 

The text goes on to describe cutting the bullet tape to allow access for the arms - implying I think that the arms are facing into the fuselage  (although the pic is not clear here and it may be that the arms are facing into the moulded hole and not into the fuselage).

 

Not sure what servos or arms they're using but I have standard Futaba 3003 servos and the arms foul (elev, rudder and throttle).  I cut back the standard "4 arm" arm to just a single one with the servos centered.

 

If I install the arms at 180deg then the arms foul the fus. 

 

So what arms do I use and how do you mount the servos then?

 

Thanks

 

Tim

[Tim Mackey]

From memory, the snakes ( which attach to the servo arms ) run along a channel in the foam, and shouldbe installed before all the CW tape was applied.

Cut the tape away where the servos will fit.

Single arm, any standard servo is fine, just wedged in tightly to the cut hole IYSWIM , and then taped over to hold in place. ( its a great model BTW )

[Tim Morton]

Tim

 

Thats right the snakes do go down a precut channel - the problem is not this it's the servo arms.  There is no room for them to fit.

 

I've got some photo's but can't seem to find an easy way to post  them so I'll try and explain.

 

The servos are a snug fit in both sides of the fus - there's no room for a servo arm to protrude either side (i.e. the arm cannot be at right angles to the servo pointing in or out)

 

The only way is is to cut back the arm really small (i.e. when the servo rotates the entire arm will still fit within the servo body)

This doesn't seem right - apart from anything else it will really affect the throw's and I doubt whether the clevis's will connect (haven't tried though).

 

Thanks

 

Tim 

 

 

 

[Plummet]

Tim,

 

The cutouts in the fuselage can be a bit undersize, and can need a bit of fettling.  (Yes I know that fettling is really the cleaning up of castings, but it does seem to suit here.)

 

If I remember correctly then the two halves of the fuselage should be covered in tape, including the two faces that will on be the centreline.  Then you cut away the tape from over the servo holes.  The tape, of course, covers the slits where the snakes will run, so the snake outers need to be in place before the tape.  

 

I recall that you do need to savage the servo arms in order for everythin to fit.  I think you just want a single arm.  I think that I used Zbends on threaded rod which was screwed into the snake to connect the snake inner to the servoarm.

 

Remember that the servos will be securely hidden inside the fuselage, so you would not be easily able to re-connect the pushrod to the servo without surgery, so unscrewing the snake inner is to be avoided!

 

In another place  http://www.rctalk.co.uk/  if you search you will find a couple of threads which we wrote while building our prangsters.  One is in IC Flying and is called Prangster, the other is called Flappit's Good News.

 

Have Fun

 

Plummet

[Tim Morton]

Thanks Plummet - just what I needed

 

Cheers

 

Tim