My brain hurts.

[Deskpilot]

As you know, I'm prone to design exotic, and probably impracticable, aircraft, one of which was my VT-ICE

 

[ATTACH=full]15911[/ATTACH]

 

This was a derivation of Mark Skull's RingTail

 

[ATTACH=full]15912[/ATTACH]

 

After Marks sad demise, I got to thinking about Vectored Thrust again only this time I dropped the all vectoring prop assembly and decided to just experiment with a vectoring duct around a standard fixed pusher prop. This is as far as I've got so far due to hitting a wall in my imagination.

 

[ATTACH=full]15908[/ATTACH]

 

[ATTACH=full]15909[/ATTACH]

 

[ATTACH=full]15910[/ATTACH]

 

Now, this shows only the pitch axis for clarity, Yaw axis being identical. As you can see, the duct is moved by pulling the requisite cable so that the top and bottom guides rotate on their balls but in opposite directions. ie, they pivot on the yaw ball assemblies. The balls provide a 3 axis bearing for combined pitch and yaw inputs. Clear?

 

Ok, you've probably seen where I'm stuck. Without compromising this ability to pivot, how do I tether the whole thing to the airframe? As it stands, wind pressure will push the duct rearwards against the tension of the cables. Nothing stops the whole thing moving forward. Bearing in mind that the duct pivots around the prop centre, and that it mustn't move off that pivot point less it hits the rotating blades, how can I secure it?

 

Why? you may ask. Because, is my answer. It's now become an engineering exercise rather than a serious attempt at designing a way out there aircraft. (Personally I still think it could work but with no real benefit) Oh, before you ask, degrees of pivot is about 12.8 from the center line all round and I know you'll think that is insufficient. Don't base your ideas on a conventional set-up. This one uses Thrust as well as normal control principals.

 

Over to you? any suggestions? Don't be shy, you all have an imagination, please use it and end my dilemma.

 

 

[Deskpilot]

Damn it, no images again. What's going on with this site Ian?

 

 

[Deskpilot]

Try again. These are the missing images. Insert them if you can.

 

 

 

 

 

 

 

[Litespeed]

Wow, that sure is a big can of worms.

 

I now understand the pain in the cranium.

 

I see where you are aiming but can't see a easy solution.

 

I think a static ring with moving blades as per your first image is the way to go.

 

I reckon unscrew the bolts on the cranium, remove brain and soak in ethanol overnight.

 

Replace with a walnut in interim until inspiration comes.

 

Drain alcohol and replace brain- all pain is gone and a solution will arrive.

 

Method has many devotees and works for me.

 

 

[winsor68]

Hey Deskpilot... how about something exactly like this... but bigger?

 

https://www.youtube.com/watch?v=m-AvNsZBzv8

 

Nice and simple...

 

 

[Deskpilot]

Thnx for your replies guys. Nice to know some one is paying attention. Litespeed, after discussions on HBA, it was thought that with a totally pivoting prop assembly, there would be too many gyroscopic forces at work to make it work, even using contra rotating props to cancel out said forces. I'm not so sure that this would be the case though. There are many thrust vectored models flying very successfully but in them, they pivot the motor as well. This makes for an easy gimbled mount. OK in a model but impracticable in full size. I'm not an engineer but I think that one only gets real bad gyro forces when there's a rim around the rotating body, like a bicycle wheel where the spokes are the blades.

 

Winsor, that's neat. Problem is, one can't buy large enough rolls of tape. Seriously though, you may have seen my thread "from Russia with love" and the plane that Serge is building. Well, add a 4 seat cabin to that model and you have what he is building. He started by building models very similar to that one shown. Thnx for you vid. It was fun to watch.

 

 

[fly_tornado]

forget the pivoting prop, vectoring thrust would be interesting!

 

 

[av8vfr]

I wonder if that would be similar to a jetski.... pull the power off and you have no directional control????

 

 

[Litespeed]

Sorry dude my brain was soaking when I wrote above.

 

What I meant is a static driveshaft and prop- no movement. And have movable vanes after the prop that direct thrust, a bit like a airboat but within the annular ring.

 

So essentially vectored thrust.

 

 

[Deskpilot]

I wonder if that would be similar to a jetski.... pull the power off and you have no directional control????

Not at all mate. The ring tail still works as per normal with the exception that it would be slightly diminished due to the smaller size.

 

 

[Deskpilot]

Litespeed, no worries, hope you're now over the hang-over. I have looked at louvres but they can only be done in one plane and hold no appeal for me.