V-tail on Gyrobee

dynacure

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Anybody concerned about the flight characteristics?
Not a horizontal stab but still some stab effect.

However, a 10000 Beechcraft Bonanza's were build with a V-tail..
But we are talking gyro's here....

Kind regards,

Willem
 

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I believe that is John Landry's gyro (username gyropilot).

If I remember right, he crashed it before he got much time on it, then he rebuilt it without the V-tail.

John, are you out there? How's my memory?
 
I have flown a V tail gyro and was not impressed with either the pitch or yaw capabilities.

Aussie Paul. :)
 
10,000 Beech 35s, 20,000 V-tail ADs. Maybe Walt didn't have such a good idea.
 
I believe that is John Landry's gyro (username gyropilot).

If I remember right, he crashed it before he got much time on it, then he rebuilt it without the V-tail.

John, are you out there? How's my memory?
Hi Chuter,

Yes... that was my Bee... before I had a wipe out during one of my early attempts at mastering the overhead stick solo. The accident damaged the tail enough that it was in need of a complete and very time-consuming rebuild. Doug Riley came to the rescue and helped me get back into the air much quicker by selling me his original Watson tail (built by Doc Watson himself).

As to using a V-tail on a gyro...

It has been used quite successfully by some in the past (namely Art Evans and someone in South Africa who's name I don't know). But I personally can't give a recommendation for it one way or the other. I never got in the air long enough to even evaluate it, and to be completely honest, even if I had got in the air, I was very unqualified to judge it's effectiveness back then.

In retrospect, I really had no business putting a V-tail on my Bee in the first place! Beginner gyro pilots have no business making major aerodynamic modifications to a proven design until they have some proper flight experience to even know what's normal or abnormal fight behavior.

Now that I have accumulated lots of hours on my Bee and a little time in several other style gyros, I'm perfectly content with a simple conventional style tail. At this point I don't see another V-tail in my future.

Best regards,

John L.
 
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Hi Chuter,

I never got in the air long enough to even evaluate it, and to be completely honest, even if I had got in the air,I was very unqualified to judge it's effectiveness back then.

In retrospect, I really had no business putting a V-tail on my Bee in the first place! Beginner gyro pilots have no business making major aerodynamic modifications to a proven design until they have some proper flight experience to even know what's normal or abnormal fight behaviour.
Now that I have accumulated lots of hours on my Bee and a little time in several other style gyros, I'm perfectly content with a simple conventional style tail. At this point I don't see another V-tail in my future.

Best regards,

John L.

A good common sense post John.

Aussie Paul. :)
 
Hi,
The control dynamics of a V-tail are no mystery. If the V-angle is 45deg, half the area is H-stab, and half the area is V-stab. It's that simple. Sure, you will have problems associated with rigidity of the boom which might not have been there with the traditional crucifix configuration, but given that the tail boom is sufficiently robust, I don't see a problem.

One of the major problems facing a designer is the mental inertia of bystanders. By this I don't mean to offend folks - but it is an obserable phenomena, and so I'm just calling it out.

Hey, look - a beer barrel will fly if you give it a rotor, an adequate H-stab and enough go-forward grunt. And you certainly aren't doing that. You're actually being very conservative.

Bottom line: At 45 deg split, your tail feathers will give you 50/50 H and V stab areas. Absolutely no reason why it won't work, providing the areas are correct. And that's the key thing. Don't rely on the eyeball method. Make sure that 50% of the area of each surface is actually sufficient for the -H and -V stab areas your aircraft requires. If you're happy with that - you're OK.

Regards,
Duncan
 
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True on the Beechcraft AD's, but that was a structural failure, not an aerodynamic one!? After the modifications they are considered to be safe.

So, no extensive flight testing on gyrocopter V-tail's...

Kind regards,

Willem
 
What I like about the V-tail in this configuration is that all the control surfases are in the high loaded prop wash area. Rigging to eliminate the P-factor the conventional way won't have much effect,I think.

Kind regards,

Willem
 
I think it would be easier to add a tall tail if you want to eliminate the p-factor.
 
Perhaps a V-tail could allow a greater surface area before risking rotor clearance issues.

Would not a V-tail introduce a pitching moment with rudder movement? If you had to stay on the rudder to deal with wind direction changes at landing, would the coupling to pitch make attitude control more difficult?
 
Would not a V-tail introduce a pitching moment with rudder movement? If you had to stay on the rudder to deal with wind direction changes at landing, would the coupling to pitch make attitude control more difficult?

That is what I was going to bring up, Hmmm.
 
Would not a V-tail introduce a pitching moment with rudder movement? If you had to stay on the rudder to deal with wind direction changes at landing, would the coupling to pitch make attitude control more difficult?

IMHO, YES.

Aussie Paul. :)
 
There are a couple of considerations.

First, the gyrobee tail tube is not mounted very rigidly. It's just adequate for a conventional tail group, if the HS is mounted low on the vertical surfaces. T-tails and V-tails typically have more mass a greater distance away from the center of the tube. They therefore impose more twisting loads on that tube than I'm comfortable with, unless the tube attachments are reinforced.

I've wiggled a couple of the large V-tails I've seen on gyros at flyins. The amount of flex/wobble they exhibit with just a light push is scary. Fatigue is a real possibility.

The V-tail in particular adds to this twist issue by acting as a small set of ailerons. A left rudder input, for example, will deflect the left ruddervator left-down, and the right one left-up. The opposing up-and-down deflections more or less cancel out pitching effects. Netted out, they produce a left yaw (as usual) and a right roll (not usual). The rotor has plenty of power to overcome the right roll, but the cancellation happens via a twisting load on the tail tube.

In a vertical descending twirl, the V-tail will try to push the nose down and to roll the gyro into the turn (like regular wing dihedral). A stable gyro already has these reactions and doesn't need the V-tail to add to them. Neither of these reactions will be strong at low throttle, but they also are unnecessary.

You get plenty of immersion of the HS in the propwash by using a conventional HS 6-8" up from the tail tube.

Innovation is good if it's directed toward meeting a specific unmet need. OTOH, novelty for its own sake is often a step backward... or at least it's an uncontrolled experiment with the Law of Unintended Consequences.
 
Someone in South Africa built a gyro using a V-tail it was not a big sucess , Mr Tirvimaki who was the basic designer of the Magni also experimented with them then went back to conventional design.
Coen.
 
Jukka Tervamaki sent a very interesting article to Rotorcraft mag. in the early-to-mid 70's. He outlined the process by which the light went on in his head about PPO. This was long before most of the rest of us wised up about PPO* (thanks to Chuck Beaty), and long before Chuck and Ron Herron dug out Cierva's old patents and found that Cierva had patented CLT in the late 20's.

After thinking through the PPO problem, Jukka made a V-tail out of two of his existing production rudder-vertical fin units, probably just to save time. He did go back quickly to a conventional H-stab with multiple verticals, as we see on today's Magni.

Interestingly, he didn't mention raising the CG in his article. He took the prop thrust's creation of a nose-down moment about the gyro's CG as a given, and employed a HS to cancel the moment. This approach, too, survives in today's Magni.

It works on the Gyrobee, too.

____________________
*Many gyro people still don't get it.
 
A V-tail induces pitching and rolling action. Using rudder and elevator together also gives some interesting sensations. Everyone that has flown a Beech 35 is familiar with the "Bonanza tail wag" in straight and lvel flight. The V-tail is not a good horizontal or vertical stabilizer. As was previously noted, you only have 50% of each. The V-tail, rather the inverted-V does have it's place. A, then, young aeronautical engineer made his mark by bending the stabilator on the F-4 Phantom and making it a safe airplane to fly. You might know him: Burt Rutan.
 
How do you uncouple the rudder from the vertical stabilizer?

When I try to imagine the rudder inputs it seems like a vertical component is a byproduct of the V tail. I would think it would produce roll as well.

It also seems to me that in a bank everything changes.

I have always liked the way it looks and I can see the advantage in rotor clearance.

Thank you, Vance
 
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