Winter build project: Wolfgang Matt’s ATLAS

It's tricky Phil, from what I've read, air will always take the path of least resistance, which becomes an issue when you are wanting to direct it somewhere. For an electric motor ideally the cooling air will be passing through it from the front, but by the nature of our planes with spinners and cowls we block off a lot of this potential cooling air.

The motor being so close to the front limits the options, as far as I can see, to gracefully direct the air onto the motor. In the case of the Atlas, you can open up the area towards the rear of the motor and hope the air will circulate, or go full monty and do what Mike did with the Blue Angel, which had 2/3 of a nose ring and a channel direct to the motor.

I also didn't want to increase the drag by carving out the cowl, with the cowl as it was, the air would hopefully have been smoothed over and around the retract bay, now it is funneled directly into it with all the retract gear and a brick wall at the end.

This is partly why I like the design of the later pattern planes like the Aurora, because you can keep to the original lines and yet still take advantage of an air intake at the front to cool the motor. But I'm learning loads on the Atlas build so hopefully when the time comes to build the next one I can undertake something a little more challenging to build. :woohoo:

In the back of my head I can hear Chirs H saying, 'just glue the thing together and fly it'

Chris001 wrote: I also didn't want to increase the drag by carving out the cowl, with the cowl as it was, the air would hopefully have been smoothed over and around the retract bay, now it is funneled directly into it with all the retract gear and a brick wall at the end.

When I looked at your cooling mod I couldn't help thinking that it looked more like an air intake than an exit. I'm no expert and could be completely wrong but I wonder whether the channel you've created from the front of the cowl is going to do more harm than good.

AlanF wrote: When I looked at your cooling mod I couldn't help thinking that it looked more like an air intake than an exit. I'm no expert and could be completely wrong but I wonder whether the channel you've created from the front of the cowl is going to do more harm than good.

You've made two fundamental errors/assumptions/misconceptions, Alan. The first is that you assume the air molecules know the difference between an entrance and an exit and the second is that you assume British molecules form an orderly cue for the exit.

The truth is that molecules will simply move from areas of high pressure to those of low pressure, and they will do so in a very disorderly fashion unless you have millions to spend on wind tunnels in order to see what it is doing.

With our models we just cut holes and hope for the best and all holes will be of some benefit for cooling

I'm currently stalled with my build, I have at least decided on the servos and hopefully should have them before too long, once I have them I can sort out their installation in the fuselage.

What I'm currently floundering on is the tail control surface linkages. Mike's running piano wire down plastic tubes, but suggested I looked at some Teflon tubing with piano wire running in it, John B has used this in his last build, and after contacting him and the suppliers it appears it needs supporting every 2-3 inches! That would be about 10 supports down the fuselage So I'm back to thinking about plastic tubing. I can find snakes with inner and outer plastic tubes, but no plastic tubes to run piano wire in! Am I missing something, or do I just buy three snakes and throw away the inner plastic?

Are there any alternative approaches/ products I should be thinking of?

The plastic tubes I used in the Blue Angel were outers from Sullivan snakes. I had them in stock and needed tubes so they got used. For the Atlas I got some tubes from Spire Models in Salisbury. They were about 60p each but I cannot be sure how many Neil had in stock. If mail ordering, these from SLEC are not too expensive.

I got my 63mm wheels from SLEC