News:


Advertise Here

  • October 31, 2020, 09:24:35 AM

Login with username, password and session length

Author Topic: RotorWing!  (Read 445 times)

Offline Dave Hull

  • 2020 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1131
RotorWing!
« on: October 18, 2020, 12:57:30 AM »
Here is my updated take on Roy Clough's rotorwing plane. It takes plenty of power but is fun. A very different flying experience. It took me a couple of tries to get the line rake correct, and to loosen up the rotor bearing to account for flex in the wing spar--which is simply a piece of piano wire. If one wing binds up and the other does not, well, you got yourself a rodeo there, pardner....

I intended to put some DARPA graphics on it, but never got around to it. But it looked good that way on my sketchpad....

It is more fun if there is a slight breeze. Going upwind, you can crank in a bunch of UP and the plane slows down because it really isn't generating enough lift to get much higher than level. So the drag goes up even further and it starts to hover. It is partly hanging on the prop. It does not do well in stronger winds simply because it is so slow there is little line tension.

There are a couple of things to remember when flying it. First, it's going to have to taxi a good ways to get airborne. Whipping just loads up the spar and may induce sufficient bending to lock a blade, whereupon the thing rolls over into the pavement. (My flying "buddies" thought that was the single funniest #$%&! thing they had ever seen at the field....)  Second, when the engine quits, it drops out of the sky nearly vertically. There is not much inertia in the rotors, and it does not have an autorotation characteristic.

Most people who see it find it oddly interesting. And it does have a certain whirring sound....

The Divot


Rotor span:    26"
Rotor chord:   3-3/4"
« Last Edit: October 18, 2020, 01:36:45 AM by Dave Hull »

Offline Dave Hull

  • 2020 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1131
Re: RotorWing!
« Reply #1 on: October 18, 2020, 01:11:40 AM »
Here is a different view showing the slotted rotors. They are made of 1/16" balsa sheet with basswood endplates. I glued a bronze bushing into each endplate. Intially the fit was good for a rigid running fit--but it locked up when the spar flexed. I ovaled the bushing (similar to what is done in a timepiece bearing) and opened up the fit as well. No issues since then.

I balanced the rotors to within the bearing friction, so it is fairly smooth in flight. I suspect that small aerodynamic asymmetries cause as much vibration as the static unbalance. But that's just a guess.

The rotors do not generate a great deal of lift. Most of the engine thrust goes toward creating lots of thrashing. Think of this as a kind of airborne threshing machine....

The original plans said to use very hard balsa for the fuselage. That's a story in itself. Let's just say I located such a piece and used it, expecting that the thing must vibrate a ton or otherwise want to self-destruct. It doesn't. And, it would be a better flyer if it was lighter, for sure.

Offline Dave Hull

  • 2020 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1131
Re: RotorWing!
« Reply #2 on: October 18, 2020, 01:23:41 AM »
I found it perplexing that there was no balance point shown on the thumbnail plans from the old magazine. So I thought about it for a bit. My conclusion was that it had to balance on the spar, since the lift and drag vectors had to go thru the rotor shaft, or else the tail would be required to do a bunch of lifting to establish the fuselage flight angle. To achieve this balance point having used petrified balsa for the fuselage, I needed to move the engine forward. I made a long spacer and trimmed it to get where it needed to be.

With this trim setup, the plane will fly level, with no "squatting at the tail." That is really helpful when the engine quits as it has less tendencies to fall out of the sky backwards onto the tail.

Online kenneth cook

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1282
Re: RotorWing!
« Reply #3 on: October 18, 2020, 06:04:02 AM »
             Dave, that's very cool. I love Roy's designs. I've always taken a liking to them.

Offline Dave Hull

  • 2020 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1131
Re: RotorWing!
« Reply #4 on: October 18, 2020, 03:13:41 PM »
Ken,

Have you tried any of them yet?  It is fun because they are so different. Just don't expect the local "stunt mafia" to show much interest. I'm looking at the drawings for the Venusian Scout next....

The Divot

Offline john e. holliday

  • 2020 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 21197
Re: RotorWing!
« Reply #5 on: October 18, 2020, 09:34:35 PM »
Yes he did have some unique designs that were fun to play with. D>K
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
AMA 23530  Have fun as I have and I am still breaking a record.

Online kenneth cook

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1282
Re: RotorWing!
« Reply #6 on: October 19, 2020, 02:54:38 PM »
           One design in particular was his "Stunt Goat" it was a stunter for a TD .09. You just don't see too many offerings for that engine and I built it. I believe it was featured in Flying Models. I didn't care for the look of the rudder but I stayed true and built it that way. I also have the Cloud Copter which hasn't been flown yet.

Offline Dave Hull

  • 2020 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1131
Re: RotorWing!
« Reply #7 on: October 20, 2020, 06:07:22 PM »
Hmmm. How does the "goat" fly?

I was looking at the Venusian plans today. Gotta find me a better paper plate.

The Divot

Offline Howard Rush

  • 2020 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 7071
Re: RotorWing!
« Reply #8 on: October 28, 2020, 01:22:43 PM »
That's really cool.
The Jive Combat Team
Making combat and stunt great again

Online Chancey Chorney

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 604
Re: RotorWing!
« Reply #9 on: October 28, 2020, 08:25:40 PM »
Well, isn't that the neatest thing I have seen in quite a while.

Offline Dave Hull

  • 2020 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1131
Re: RotorWing!
« Reply #10 on: Yesterday at 02:52:25 AM »
Here's an in-flight photo from last year with my friend Ron Duly at the controls. You can tell it's a pretty casual plane to fly--as long as you have line tension.

Notice that the rotor panels are completely independent and are not synch'ed up in any way. I think as long as the rpm is high enough, any roll wobble is mostly damped out.

The Divot

Offline Norm Furutani

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 201
Re: RotorWing!
« Reply #11 on: Yesterday at 02:19:01 PM »
Dave
You need to build a Clough Little Dragon to power it! See: http://modelenginenews.org/design/design6.html

Norm

Tags:
 


Advertise Here