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converted pylon racer

BATTLEAXE

Well-known member
#22
@BATTLEAXE - thanks for the kind words - I usually dream up the parts overnight and print something in the morning - I have been having no end of issues with printing lately - the final proof will be in the air!

I have not flown in weeks! :eek:
Looks like things are gonna get a little colder, like -10, and some decent snow falls so I might set up the Sportster with the floats for take offs and landings, maybe there will be some calm days to take out the BW. I haven't flown in a couple days either and the weather might get cold enough to not be able to stand outside for to long so we will see.

I tend to get a lot of my inspiration overnight as well. I have been known to wake up at 3am sometimes and head to the garage just to get an idea out of my head. if I don't do it I can't get back to sleep lol.

When are you going out to fly?
 

Piotrsko

Well-known member
#25
Looking at your proposed drawing AND the actual elevator horns, experience tells me that I believe you don't have enough flex In your pushrod scheme. If you move the surfaces by hand, you will find the rods need to flex inward and outward significantly and sort of rotate 45 degrees. While the original set up was rather gross, it was the more efficient.
 

Piotrsko

Well-known member
#27
Unfortunately, V tails have this annoying requirement that the control horns don't tend to move in a linear path. They move in and out unless you get creative with the linkages. Some like the aforementioned pylon racer will even twist while going in an out. To compensate, you allow the pushrod to flex in the last foot or so. V tails should always be pull for up because of the flex unless you fly inverted a LOT.
 

bracesport

Well-known member
#28
@Piotrsko - yes, this is a pull-down, push-up arrangement - the original parts were rigid and I guess only had a few millimetres of movement without tearing the hinges (actually there is a bit of delamination) - my 0.8 mm section of the pushrods will provide the flex between the control arm heads, and the ball socket will account for the twist.
 

BATTLEAXE

Well-known member
#29
Unfortunately, V tails have this annoying requirement that the control horns don't tend to move in a linear path. They move in and out unless you get creative with the linkages. Some like the aforementioned pylon racer will even twist while going in an out. To compensate, you allow the pushrod to flex in the last foot or so. V tails should always be pull for up because of the flex unless you fly inverted a LOT.
Oh ok i get it. Its just the arrangement of the linkages. Makes sense. I was thinkin of something different.
 

Piotrsko

Well-known member
#30
@Piotrsko - yes, this is a pull-down, push-up arrangement - the original parts were rigid and I guess only had a few millimetres of movement without tearing the hinges (actually there is a bit of delamination) - my 0.8 mm section of the pushrods will provide the flex between the control arm heads, and the ball socket will account for the twist.
You are aware you can flex pushrods so many times before they fail by fatigue usually at a bend. Could be as soon af the first flight. JUST SAYING. Wonder how I would know that fact?
 

Wildthing

Well-known member
#31
You are aware you can flex pushrods so many times before they fail by fatigue usually at a bend. Could be as soon af the first flight. JUST SAYING. Wonder how I would know that fact?
So I am confused, first you want flex and now you say it can possibly fail first time out??? Is it the V-tail ?
 

Piotrsko

Well-known member
#33
So I am confused, first you want flex and now you say it can possibly fail first time out??? Is it the V-tail ?
Flex spread over a decent distance tends to not induce failure while flexing over a short distance causes metal fatigues. I do not have enough engineering skills to calculate that critical distance. V tails tend to require a flex to operate. Make a dummy one and try it.
 

bracesport

Well-known member
#35
here is the final assembly - the width way flex is only about 5mm aside if that - I drilled a hole through the CG rod, made a bend on the ends of each wire and inserted them into the holes - I also filed a V into both sides of the CF rod to seat the wires and then wrapped them with Kevlar braided line soaked in epoxy - looks pretty good!

IMG_7982.JPG
IMG_7983.JPG
 

BATTLEAXE

Well-known member
#36
Where do you get the Kevlar line from? I am thinking like a braided fishing line would work, no?

Oh hey side note- I have been playing around with a simple free RC flight sim on my tablet and have been getting the hang of this slope soaring thing. No gentle landings yet but definitely worth slapping together the simple soarer to try it out.
 

BATTLEAXE

Well-known member
#40
Looks like you got some pretty nice weather on that side of the planet. I watch Xjet (Bruce Simpson) a lot who happens to be a Kiwi, he gets out and flies from time to time. What's goin on with that silver beauty hiding in the mix, does that fly??!! :LOL::p