V-Tail?
 

Hey guys, hope the new year is finding you all well.
Im finishing off my design right now, and would like to put a V-tail on it.
Just wondering if anyone else has tried this, any suggestions?
Im planning on using the tail area formulas given at the autogyro,com site.
Thoughts appreciated.
Its a co-axial pusher.

RE: V-Tail?
 

wow 16 veiws and not one reply[sm=confused.gif]

RE: V-Tail?
 

Mr Spaceball....

You have chosen a tough row to hoe.
Coax rotors, Pusher and you want it to be a V-tail.............

I dont want to squash your dreams but I believe it would be in your best interest to start with a proven design, learn a few things and then design your own model.

Rick

RE: V-Tail?
 

Hi Spaced,
Rick offers excellent advice!
Can say this> an excellent Gyro modeler evaluated V tail versus
usual.
Finding was mysterious problems,actions disappeared when V was
replaced with a normal arrangement., OK?
Good luck,

Hal deBolt

RE: V-Tail?
 

Gyronut, I have a gyro similar to a gyrace. Baically a uglystick with wing stubs an twin rotors.
The reason Im doing this design is as a part of an ongoing project.
I dont mind spending time getting it to work, the design is the part I enjoy the most.
I was only wondering if the v-tail had been tried.

Thanx Hal

RE: V-Tail?
 

Hello Hal

In your original post didn't you mention something about a Co Axial Pusher model......??????

Now in your last post you mentioned that it is a Tandem " side by side " model is it still a pusher model or is it a tractor model.... that you want to add the V-Tail too......???? Theres a night and day difference between the two models ya know.

Anyway.............I have tried the V-Tail thing and it is not worth your time to even try it. It does not work at least following any kind of normal design pratices.....I suppose if you made one with say 300 sq in. of area it might have a chance but aside from that dont waste your time.

Would be cool though.


Rick

RE: V-Tail?
 

Hi, Spaced,

I tried a V tail single rotor DC gyro about 4 years ago.
It didn't work well so I went on to other projects.
Go to Spring Hill next week to the gyro meet and learn more & have some gyro fun.

Good luck,
Bob G

RE: V-Tail?
 

Gyronut, even though you you addressed your last post to Hal, it seems you were talking to me so Ill reply.
In your first post you stated to build a gyro of standard design, and learn a few things. I already have a standard gyro, the converted ugly stick, which is a tractor, side by side layout.
The design Im working on is a coax pusher.
Dont know where you got the tandem bit from.

Anyway thanx guys, Ill steer clear of the v-tail for now.

RE: V-Tail?
 

Has anybody ever flown a coaxial rotor job? Sounds an interesting system but would not the interference between the rotor discs cause a lot of
inefficiency? Perhaps result in less lift than a single rotor? Question to Spaced - Are you not wanting to use regular hinged rotor blades?
Colin

RE: V-Tail?
 

There are plans available for "Al's Autogyro". It is a tractor design with coaxial, two-bladed rotors. Because the rotors are set up to be counter-rotating, there is no need for flapping blades, etc to offset centrifugal force problems or unbalanced lift forces. However, I built an "Al's Autogyro" according to the plans and found that one of the rotors would always be "lazy".

The two rotors could be interchanged and the one in one of the positions (top or bottom) would always just barely get rotating. I don't remember whether it was always the top or bottom one, but it always was the same location that was lazy.
As I recall it never did get off the ground.

Maybe it was my poor craftsmanship, but I really tried to get the thing to fly.

Bill

RE: V-Tail?
 

tintrax, Im not planning on using hinges, at the moment its a ridgid system, but Im not sure whether the blades will rotate at the same speed or not. Ive got 2 layouts at the moment, one with a flapping head one without, after reading billf's post, I may skip the ridgid and go straight to the flapping.
As part of a design project Im working on a new rotorcraft design, part of the design requires the ship to be a coax, thats the main reason for the rotor layout.

billf, I would think that the top rotor would be slower than the bottom as its operating in the wash of the lower rotor.If you dont mind, whats the rotor diameter of yours, the space between the rotors, and did you have different blade incedence on the top and bottom rotors?
Thanx

RE: V-Tail?
 

Spaced:

I wish I could remember the exact dimensions you ask about. But I THINK that the separation between rotors was about 3-4 inches. No, I didn't use different incidence on the two sets of rotor blades---might be a good approach! You probably are right that the wash from one rotor affects the other.

Anyway, interesting project. We all will be interested in how it works out.

Bill

RE: V-Tail?
 

V-tails a bad idea ????? Nonsense

Here is my Whirling Dervish. It flew really well and was fully aerobatic. As you can see it has a v-tail.
I actually tried a normal tail as well but there wasn't that much to choose between them. If anything the conventional tail gave better stability in strong winds but the v-tail acted like a dihedral wing and gave a higher roll rate when used with dc roll on the head. Personally I like the look of a V-tail. If you are interested the internal V angle was 120 degrees. Pitch stability was the same for both types of tail.

Sean

RE: V-Tail?
 

Bill

I built a co-axial gyro from a converted fixed wing fuselage. I used the same hub arrangement as Al's but used proper sectioned blades instead of the flat paddle type. The blades had an incidence of around +1 degrees and self started by angling them forward 45 degrees before the take-off run. It flew superbly and both rotors appeared to be rotating the same. In fact it flew so well that i am currently building a small version using an .09 size engine. Maybe my model was just a fluke and this new one I am building will have the 'lazy' rotor. We will see !!

Sean

RE: V-Tail?
 

Congratulations, Sean!! Interesting that you can get "self starting" with +1 degree of incidence. In any event you have accomplished a significant result!

BTW are you aware of the Cierva Prize Fly-in to be held early this May in Madrid? I'm sure that your dual rotor and Vee-tailed models would be most welcome there.

Bill

RE: V-Tail?
 

Hi Ya'll,
Pay attention to Sean, what is said is excellent and good stuff.
One thought> Biplane aerodynamics says a 1 1/2 chrod spacing
assures no interference between wings.
Would think 2 chords for a rotor would be good insurance and not
unwieldy.
Hey, good luck and keep us informed, OK?

Hal

RE: V-Tail?
 

Rotor Separation

Interesting statement there regarding rotor separation. It would appear that when Al was designing and testing his gyro design he found a simple way to achieve good separation without having to move the two hubs too far apart. Its hard to see on my photos I posted but the separate rotor hubs used different dihedral angles for the rotors. The lower two blades had an internal angle of 186 degrees with the upper having a much reduced internal angle of 172 degrees. This gives a very large separation well in excess of 1 1/2 chord width by the time you get halfway out along the length of the blades. I must also add Bill that the aforementioned co-axial gyro re-kitted itself spectacularly one fine day when my complacency far exceeded my flying ability.............good design though ;)

Bill, the plus one figure I stated is not precise.I used a flat bottom rotor section which by the definition of incidence does give around +1 incidence ,however, I have never succeeded in getting a rotor to start and move in to autorotation unless the blade undersurface has at least a small amount of negative angle relative to the rotational plane. One exception is my Jim Baxter type delta hub with its blades mounted with the falt bottom flush with the tangs in flight this probably gives a slight negative angle when taking coning angle in to account. All my gyros use a single mounting bolt on each blade so I can angle them forward for simple starting even in no wind. I think it was an idea first pioneered on models by Georges Chaulet.

RE: V-Tail?
 

Sean....
That may be the reason you have been successful and I was not!! Good insight!!

Bill

RE: V-Tail?
 

Hi Spindizzy,
Congrats, on your success with V tails that have eluded the rest of us.
Could you supply more details of your Whirling Dervish design?
Thanks,
Bob Gardner

RE: V-Tail?
 

Wow, I should go away for a week more often.
Thanx for the replies guys.
Spindizzy, if I could ask a couple of questions.
The tail area of your V-tail, is it equal to the area of your hstab, vstab?
What is the rotor dia of your coax? and disk loading?

All of my calcs have been based on coax helo formulas, so bringing them across to gyros has been an interesting experience.
I have a paper done by NACA on the best spacing for the rotors, which is 10%R. This seems to be the best mix between drag of the second rotor, and losses from the other rotor.

RE: V-Tail?
 

Being a NACA addict: which NACA TN/TM/Report?

tia
Torbjörn

RE: V-Tail?
 

Spaced

With regard to the area of the V-tail my method of deciding how big to make it was not exactly 'scientific'. I simply ensured that when viewing the tail from the side, the area that was visible matched the visible area of the conventional fin. Same went for the horizontal stab when viewed from above. Needless to say the overal result of this is that the v-tail is physically larger than a standard tail. Were my new gyro having only a single rotor system I would be aiming for a disc loading of around 3.5 oz/sq.ft. With a two blade co-axial rotor do I half this figure ??
This loading figure is based on my other small gyros that always end up around 3.5 - 4 oz/sq.ft.

Rotor diameter will be 32" on my new design with power suplied from a Hornet .09 with a 7x4 prop.

Cheerio

Sean

RE: V-Tail?
 

hi ; i have had a few hours in pusher gyros ; the real thing ; a few guys make tractor autogyros ; none make the coaxial ; dr igor bensen made a prototype coaxial pusher which
could easily have been a tractor ; in fact , a friend of mine has made a tractor autogyro by
modifying a brock bensen pusher gyro ....... but i digress ; if you want to see a picture
of a real coaxial autogyro in flight , search key words : B-8MH gyro and you will see dr
bensen flying his creation ;
duggy