[brianscharp]

Ah, remember Bob Lovejoy's Hightailer? I think he was achieving the necessary ground clearance for a Quicksilver type HG. However, it never went into production and the Quicksilver did, so maybe it didn't provide enough pitch stability. Personally, I don't know the reason but Dave Cronk might.

FC

I don't remember hearing about it's flying characteristics. I've also wondered how effective the rudders could have been so close to the root.

[Frank Colver]

I've asked Dave Cronk about it. I'll post his reply when I get it.

Frank

[ARP]

Kia,

At this pre-construction stage I have not released any drawings of the glider. The V tail is close coupled in a bird like fashion and much the same as the one used on my Lilienthal type glider. Unlike the Lilienthal and Pilcher gliders it is fixed and not allowed to swing up as you also suggest to allow a flare on landing. I see little difference of the extended keel of a delta flex wing with a comparable length V tail plane assembly.

[Frank Colver]

Here is Dave Cronk's reply about Lovejoy's Hightailer.
FC


Hi Frank,

The Hightailer was a very cool-looking glider, but it had several fundamental problems:

• The short coupled wing/horizontal stabilizer made for marginal pitch stability and very sensitive pitch control. Basically it was dangerous.
• The short-coupled vertical stabilizers gave very poor yaw control. As this is a yaw/roll coupled design, roll control and stability were marginal at best.
• The triangle bar and bracing elements created a 4-bar linkage that was structurally unstable.

I convinced Bob to add a conventional tail arrangement that was perhaps mundane, but this eliminated the problems listed above. The rest is history.

The Quicksilver always required a tail-man, and that was a major drawback for foot launching. The tail man could make or break the launch, so I always tried to have someone along who knew what they were doing.

I can give a more detailed history if you think there is interest.

Hope all is well, hope to see you in the SW this fall.

Cheers,

Dave

[JoeF]

I will be robustly exploring what for years I have called "High-Hat" horizontal stabilizer for pitch stabilizing, but stay with tip controls for yaw/roll coupled with weight-shift. Accepting the drag of streamlined holders of upper extensions of the triangle control frame queenposts to give two king posts; the two kingposts will form the foundation for the horizontal high-hat stabilizer perhaps with some direct control. High-hats for HG arrive in very many sizes from that of Icarus I or Icarus II to small trim decorative high hats. Experimental; no results to report yet.

HighHat004.png (4.25 KiB) Viewed 10106 times

[JoeF]

Kia,
At this pre-construction stage I have not released any drawings of the glider. The V tail is close coupled in a bird like fashion and much the same as the one used on my Lilienthal type glider. Unlike the Lilienthal and Pilcher gliders it is fixed and not allowed to swing up as you also suggest to allow a flare on landing. I see little difference of the extended keel of a delta flex wing with a comparable length V tail plane assembly.

SUPPORT IMAGE FROM ARP:

I will give further details of the design once it is complete and test flown. ~ARP

2015PrenticeShortPack2mAAA.jpg (38.01 KiB) Viewed 10097 times

[KaiMartin]

I will be robustly exploring what for years I have called "High-Hat" horizontal stabilizer for pitch stabilizing, but stay with tip controls for yaw/roll coupled with weight-shift.

Interesting concept.
Let's see. The "hat" would act in a similar way as the horizontal component of a traditional tail plane. Its angle of attack should be a few degrees lower than the main wing. Unlike the tail plane, the major contribution to stability is not the differential of lift between tail and main plane. It is the differential of drag. Fortunately, (induced) drag and lift are proportional. So this might actually work.

Probably, the hat must be a pretty high one. I'd expect a viable height to be similar to the distance of wing and tailplane in traditional configurations. This would be 3m upwards...

Has this kind of pitch stabilization been demonstrated in models?

---<)kaimartin(>---

[KaiMartin]

The V tail is close coupled in a bird like fashion and much the same as the one used on my Lilienthal type glider.

Soaring birds do not use their tail for pitch stabilization. They either use it for yaw control (birds of prey). Or they don't use their tail at all when on glide (sea birds).
Birds of prey keep their tail at an angle which is larger than the main wing. If anything, this adds even more instability to the already severely unstable main wing. According to traditional (model-) plane construction theory this is a recipe for disaster.

Birds are of course able to soar anyway. They cheat by constantly adjusting the configuration of their wings. Very much like we keep riding a bike. From the perspective of flight mechanics, only unstable configurations would warrant the attribute "bird like".

Unlike the Lilienthal and Pilcher gliders it is fixed and not allowed to swing up as you also suggest to allow a flare on landing.

I was not aware that Lilienthals tail was able to change its angle of attack relative to the main wing.

---<)kaimartin(>---

[JoeF]

I will be robustly exploring what for years I have called "High-Hat" horizontal stabilizer for pitch stabilizing, but stay with tip controls for yaw/roll coupled with weight-shift.

Interesting concept.
Let's see. The "hat" would act in a similar way as the horizontal component of a traditional tail plane. Its angle of attack should be a few degrees lower than the main wing. Unlike the tail plane, the major contribution to stability is not the differential of lift between tail and main plane. It is the differential of drag. Fortunately, (induced) drag and lift are proportional. So this might actually work.

Probably, the hat must be a pretty high one. I'd expect a viable height to be similar to the distance of wing and tailplane in traditional configurations. This would be 3m upwards...

Has this kind of pitch stabilization been demonstrated in models?

---<)kaimartin(>---

Yes, Kai, some modeling and model test gliding has been done with encouraging results. Notice that the high hat is shading the main wing some. And that the high hat is in clean air streams. A high hat of even blunt drag has some interesting dynamics. I've taken for glide test model pitchy (no reflex) monoplane wing without tail but just with high hat; it takes surprisingly little high hat area on its upper lever to effect pitch-up moment. Some of the preliminary meditation was being unfolded in my Oz Report topic where I played more broadly with the term "High Hats"
See the nine pages: http://ozreport.com/forum/viewtopic.php?t=19723
I am even exploring tumble-wings set between the two kingposts (reverse tumble: LE goes up to zenith; looking from main flight wing port towards starboard: see the tumble wing rotating clockwise); the tumble wing rotates faster when apparent wind is increased; and it slows as apparent wind speed decreases; though the tumble wing is low L/D, it is with its special dynamics as well as with its entertainment look as it spins; one might wonder if that tumble wing is some kind of propeller when actually it is just a non-engined rotating wing; in HG high flight one would not want a tumble-wing high hat to reverse its direction of rotation (so, a one-way ratcheting direction keeper would be wanted).

See: Walkalong fly forever tumble wing

[ARP]

Kai,

I think you will find that birds use their tails in various ways at different stages of flight. They are also used to attract a mate but I have not added one for that purpose. In this proposed design the tail is bird like in its location and shape. It lines up with the airflow and only provides a corrective pitching force if the wing angle changes. It is able to move in sync with the billow shift of the sail to give a rudder effect to enhance turning. The design is based on my earlier splitwings which had no tails and much more pronounced diamond shape plan form.

Lilienthal, Pilcher and Chanute all employed tail planes that floated up. This can be seen in a video of Stephan Nitsch's replica :- https://www.youtube.com/watch?v=mpDrGLF51SY In my version the tail was fixed as I feared that no corrective force would allow the wing to pitch up too much and stall. The very thing that killed Lilienthal.

Tony