John Ralph's Wagtail
Posted: 31 Dec 2018, 20:01
I noted a recent reference to the Wagtail in another topic and I thought this would be a good moment to post some photos of my own, newly-built Waggy.
It's electric (3S 1800MAh/ 150W per lb.) and the control system (naturally) is GG. In fact, it's another iteration of the prehistoric Mighty Midget - type actuator that's served me so well. The only difference is that this time I opted to mount it in the vertical plane rather than horizontally. Seems to work just as well and, in some respects, is more convenient.
The other change I made was to concoct a simpler method of mounting the nosewheel. The original had the nosewheel leg soldered to a piece of PC board, and this in turn was stuck to the underneath of the model with either Evostik or Araldite. I didn't fancy that, so I inset a 4mm birch ply plate into the lower sheeting and attached the u/c with common or garden nylon clamps.
The only tricky bit of the actuator/birdcage set-up is getting the necessary throws on the rudder and elevator (the actuator has plenty of power). That's 35 degrees each way on the rudder and 12 degrees of down/35 degrees of up for the elevator. It needs a quite acute bend on the wire end of the torque rod: something like 40 degrees in order to get the deflections you want. That involves a bit of cut-and-try, and, as happened the last time I did this, I had to remake and juggle with the elevator linkage. If it isn't right first time - and it probably won't be -It takes a good deal of looking-at, squinting and teeth-sucking to work out what you need to do! All good fun.
The model needs a bit more decoration but I may wait until it's been proved before doing that.
Cheers
David
It's electric (3S 1800MAh/ 150W per lb.) and the control system (naturally) is GG. In fact, it's another iteration of the prehistoric Mighty Midget - type actuator that's served me so well. The only difference is that this time I opted to mount it in the vertical plane rather than horizontally. Seems to work just as well and, in some respects, is more convenient.
The other change I made was to concoct a simpler method of mounting the nosewheel. The original had the nosewheel leg soldered to a piece of PC board, and this in turn was stuck to the underneath of the model with either Evostik or Araldite. I didn't fancy that, so I inset a 4mm birch ply plate into the lower sheeting and attached the u/c with common or garden nylon clamps.
The only tricky bit of the actuator/birdcage set-up is getting the necessary throws on the rudder and elevator (the actuator has plenty of power). That's 35 degrees each way on the rudder and 12 degrees of down/35 degrees of up for the elevator. It needs a quite acute bend on the wire end of the torque rod: something like 40 degrees in order to get the deflections you want. That involves a bit of cut-and-try, and, as happened the last time I did this, I had to remake and juggle with the elevator linkage. If it isn't right first time - and it probably won't be -It takes a good deal of looking-at, squinting and teeth-sucking to work out what you need to do! All good fun.
The model needs a bit more decoration but I may wait until it's been proved before doing that.
Cheers
David
