V-tail

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

rtfm

Well-Known Member
Joined
Jan 3, 2008
Messages
3,233
Location
Brisbane, Australia
Hi,
Yes, greater drag also. Still thinking about this configuration. Might decide not to go this route after all. But at the moment, I'm still weighing the pros and cons, and trying to decide which set of compromises I can best live with.

H-stab in the wing wake? No - I can't see this happening. The wing "shadow" extends rearwards from the its trailing edge at an angle of about 60 degrees, even in a deep stall. The h-stab isn't anywhere near that...

Regards,
Duncan
 

autoreply

Well-Known Member
Joined
Jul 7, 2009
Messages
10,751
Location
Rotterdam, Netherlands
Duncan, I can't give you any quantitative answers. The best place to find them is usually the biplane department since it's closest to a biplane configuration (but then for your tail)
 

rtfm

Well-Known Member
Joined
Jan 3, 2008
Messages
3,233
Location
Brisbane, Australia
Hi,
Raymer (Homebuilders edition, pp38, 39)
"In a spin the horisontal tail is at an extreme angle of attackand is throwing a turbulent wake behind itself, extending upwards along roughly a 60 degree angle from the leading edge and a 30 degree angle from the trailing edge."
This effect is noticed with reference to the wing also, as he illustrates in his accompanying diagrams.. I've attached a sketch illustrating this wing turbulance for the Razorback.

I was measuring from the vertical backwards - but I see Raymenr references the horisontal plane upwards. No difference.

Regards,
Duncan
 

Attachments

Last edited:

lr27

Well-Known Member
Joined
Nov 3, 2007
Messages
3,822
Aha, I get it now.

The set of all spins does not entirely contain the set of all "high angles of attack". I.e. a straight stall, for instance, or even an approach to a stall, would count as a high angle of attack. Maybe that's ok, though. I've seen an argument that if the stab dips into that before the stall break, you get lots of shaking to wake up the pilot. Which is what a "stick shaker" is supposed to simulate.
 

rtfm

Well-Known Member
Joined
Jan 3, 2008
Messages
3,233
Location
Brisbane, Australia
Hi,
I would really appreciate some help with trying to decide on whether or not to configure the Razorback with a single T-tail or a twin vertical + h-stab attached to the top of both.

My main concern is with rigidity. The Razorback will cruise at 150kts, which is pretty quick, and the last thing I need is a T-tail which isn't able to cope with the asymetrical flight loads. I could really beef it up, of course by using a fat airfoil, and having two substantial spars with graphlite spar caps. Then attach the h-stab with metal fittings suitably secured into the spars. This was my original plan.

But I could get away with a far less substantial construction by using two vertical tails anchored to the Stongback at the base, and "triangulated" by the h-stab attached to their tops. Each tail could be less massive, and the weight penalty would be less than one might expect from doubling up on tails.

There would be added wetted area (each tail is 5.8 ft^2) and added interference drag. But the entire tail section would be very rigid, and worries about flutter at high speeds would be a thing of the past.

The twin tails would be more difficult to build. Both a T-tail and twin tails would look cool, but the twin tails would be cooler, I think. At least more unusual.

What do you think?

Duncan
 

Hot Wings

Grumpy Cynic
HBA Supporter
Log Member
Joined
Nov 14, 2009
Messages
7,085
Location
Rocky Mountains
Hi,

What do you think?

Duncan
Since you're asking for opinions:

I'd prefer the V-tail for looks and because I don't know what kind of asymmetrical loads the stab would see in flight. This, for me, would make designing of the pivot kind of a speculative proposition.

Another option if you are uncomfortable with the standard T-tail strength is to add a couple of simple flying wires or small streamline tubes at mid span? This could triangulate things with a minimum of weight and cost.
 

autoreply

Well-Known Member
Joined
Jul 7, 2009
Messages
10,751
Location
Rotterdam, Netherlands
Hi,
My main concern is with rigidity.
I doubt a twin tail is much better at that. Most T-tails have their highest loading at the tailtube they're mounted at, like an internal torque in your tail cone. A double tail will have that too. In fact, the loading on a t-tail (with a high aspect ratio) is pretty low and I'm quite sure it'll be lighter as a double tail. Why not go for a cruciform tail?
 

Dana

Super Moderator
Staff member
Joined
Apr 3, 2007
Messages
9,262
Location
CT, USA
hello as I can get the plans of monerai? thanks
The Monerai was only sold as a kit, and according to The Monerai glider web site, "Without major re-design, scratch building a Monerai would be very difficult. The extruded parts for the wing (Spar, connecting knuckles) and the boom (Boom tubing and fittings) and the molded parts (fuselage shell and canopy) are not available."

-Dana

"If you want to build a ship, then don't drum up men to gather wood, give orders, and divide the work. Rather, teach them to yearn for the far and endless sea." - Antoine de Saint-Exupéry
 
Top