Clearance

[gyroman]

All you guys that have finished gyrobee's out there, I need a dimension. What is the distance between rotorblade (pulled down) and the tailboom?
In other words, if I were to make a tall tail, what is the maximum height that would work on the 'bee without the blades hitting the tail at full back stick. I don't have rotorblades or a rotorhead yet so I need this info to start work on the tail.

[KDOG]

Gotta consider flex too, not just the distance between the two when its sitting on the ground. Good question, though.... I'll be using the Starbee tail since I hear its a fantastic tail. I don't know the dimensions of that either. Yes, I'm useless.

[gyroman]

Yes flex will be accounted for but I really need the dimensions. Everyone should be back from BD now... anyone got the time to measure their 'Bee?

[gyropilot]

Toby,

If no one gets you the info sooner, I should be able to measure my gyro later this weekend when I get up to the hanger and put the blades back on.

Regards,

John L.
Shoreline, WA

[Brian Jackson]

Toby,
I'm anxious for someone to answer definitively as well, since this seems to be a gray area. I can see why though, as there are numerous variables in the chain to arrive at a specific value. Your head travel, it's fore/aft location (which depends on the cheek plates, whose design is resultant of your hang test), stick travel, blade flex, teeter stops, hub bar coning (if any)... the list goes on.

So what one builder measures on his/her specific machine may be quite different from that of a similar machine unless they're factory-built to identical specs.

I'll be looking forward to any responses on this topic.

Respectfully,
Brian Jackson

[Brian Jackson]

I also wanted to add that I'm not speaking from experience. I'm just conveying some of what I've learned here by studying.

[gyroman]

John,

Did you get a chance to check the measurement this weekend...

[Jim]

This is how I calculate the height of the mast or how low the tail must be:

1. Calculate where your centre of gravity will be. In my example it will be the centre of the round green circle. Draw a line 11degrees back from this point. In my example it is orange.(Some draw this at 9 degrees to incorporate the two degrees coning. Whatever you do, consult your plans.)

2. Find the highest point of your giro’s rear or the ground at the rear that your blades (or the tip of your blades if it is the ground) will strike. In my example it is a red line. From this draw a line of 25 degrees. In my example it is dark blue.

How did I arrive at 25 degrees? The rotor rides at about 11 degrees backward. Subtract two degrees for coning. That gives 9 degrees. Add 8 degrees for flapping, add 8 degrees for full back control. 9+8+8=25. If your stops are more than 8 degrees, this angle will, off course be more than 25 degrees!

3. The blades are not rigid, to compensate for this it is a good idea to allow about a foot for this flapping. The light blue line is a foot higher than the dark blue one. Where the orange and light blue lines cross is the teeter point of the rotor.

[RICK MARTIN]

Sorry Toby, I can't get to the gyro this weekend. But I'll monitor the thread and if you don't have what you need by Monday, I might be able to take some measurements.

[ultracruiser41]

Toby,

The clearance will be different with different rotorheads. I temporarily installed a bensen head on my bee and my sportcopter rotors could hit the ground in front and back just tilting them! With my souza head, I can't. I'll be out this week and get you the measurements on mine.

BarryK

[gyropilot]

Sorry guys,

I wasn't able to put the blades on my Bee this past weekend, so no meaurements yet. As soon as I do I'll share the results here.

Best regards,

John L.

[gyropilot]

OK,

Got the chance to measure the blade to frame clearance on my Bee this afternoon:

I measured 57-1/2" from the top / aft edge of the tail boom to the underside of the blades with the rotor head tilted all the way aft and the hub bar against the aft teeter stop. This is with 23' Dragon Wing blades and normal static droop.

The tail boom is 54" from the rear of the mast to the end.

Some additional interesting info:

I measured 23" of clearance between the very top of the Watson tail and the underside of the blades.

I have 12" of clearance between the blade tip and the ground behind the gyro, when the gyro is resting on the main wheels and the tail wheel.

There's 8-1/2" of clearance between the prop tips and the underside of the blades... this is using a 60" Ivoprop on an oil-injected Rotax 503, so the prop is significantly aft of where it would be when using a Rotax 447. There's 3-1/2" of clearance between the prop tips and the tail boom.

To sum it up, the GyroBee has MILES of clearance between the blades and just about anything on the gyro! You'd really have to try hard to hit something (can you say severe flapping?).

Best regards,

John L.
PRA Chapter 30
Western WA State

[Alan Coats]

That's good info John.

Thanks for the information on the scissor linkage you sent me by e-mail also.

Alan

[gyroman]

As usual, thanks John, you are a great help to us guys working on our gyros. Thanks for taking the time to go out and get the measurements. It's good to know I have that much room to work with.

[Brian Jackson]

I measured 57-1/2" from the top / aft edge of the tail boom to the underside of the blades with the rotor head tilted all the way aft and the hub bar against the aft teeter stop. This is with 23' Dragon Wing blades and normal static droop.
John,
Was this measured vertically or at an angle perpendicular to the blade? I ask only because it affects the dimension since the blade's at an angle in relation to the tailboom.

This is fantastic info, and I sincerely appreciate your taking the time to acquire it and present it here.

Thanks,
Brian Jackson