Tall Tails, short tails, horizontals????.....again.....

[Jean Claude]

I wasn't talking about the value of the load to be supported, but about the method of construction. Using carbon fiber as black sheet metal is a great waste of work and money.
Carbon fiber allows great mass gain for the same load structure, but this requires much more thoughts.
Hence my overly brutal and simplistic terms of "stupid" and "smart".
I didn't mean to offend you, Jimmy.
Just to explain in a few words the possibilitys for best lighty and the reasons for failure.

 

[Jean Claude]

Jimy had asked how thickening the tail profile wouldn't be bad at the drag.
Here is my opinion:
Naca report n°610 tells us that Cd0 of the NACA 0012 is 0.007, while Cd0 of the NACA 0018 is 0.0085,
At 120 km/h the profile drag of the tail (1.6 m2) is therefore increased by only 2 N. (Profile Drag = 1/2* Rho* S* V^2* Cd0 )
But if increasing the relative thickness from 12 to 18% reduces the weight of the tail by about 30% (i.e. about 3 kg), and the L/D ratio of the gyrocopter is 4, the induced drag of the rotor is reduced by about 7 N.
Thickening the tail section can therefore reduce overall drag.

 

[C. Beaty]

JM & JC: highly technical discussions in a foreign language often lead to misunderstandings and imagined insults where none was intended.
If we were discussing the law, JC and I would be the dummies but who cares?

 

[giro5]

Gentlemen I am not trying to cause anyone any grief just putting out a couple of ideas that popped into my pea sized brain lately.
One - did Bensen have the heavy slab tail on purpose to help mitigate PPO. And two - at the speeds a lot of gyros fly at say 45-75 mph if one made a foam/fiberglass tail and left it with the weave exposed instead of fairing it would it really make any difference on the cruise airspeed of the gyro. I don't think it would make even one mph difference.

And one more thing although weight is always a consideration I know that even with 22 ft brock blades a giro glider will pick up two people easily. Of course that is kinda like having unlimited horsepower.

 

[Hosko]

Here is a tall tale example. I tried something like this first but it was heavier than the t tale and I like the t tail more.
Used mico ball for filler and some small amounts of bondo to get the surface baby butt smooth. Peel ply and vacuum bagging is a must if you don't want more resin than is desired. Sanding is the pain in the ass part but the results are worth it. Credit to Eric Hosko for tall tale.
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I've made a number of that type of tail . Ampreg 22 epoxy resin & woven glass not chopped strand. Foam core vertical tail is cut by cnc hotwire , the horizontal stabs i cut with with home made hotwire & aluminium templates.
Weight finished is about 6kgs.

Here is a tall tale example. I tried something like this first but it was heavier than the t tale and I like the t tail more.
Used mico ball for filler and some small amounts of bondo to get the surface baby butt smooth. Peel ply and vacuum bagging is a must if you don't want more resin than is desired. Sanding is the pain in the ass part but the results are worth it. Credit to Eric Hosko for tall tale.
View attachment 1149299View attachment 1149300View attachment 1149301View attachment 1149302

 

[Hosko]

Here is a tall tale example. I tried something like this first but it was heavier than the t tale and I like the t tail more.
Used mico ball for filler and some small amounts of bondo to get the surface baby butt smooth. Peel ply and vacuum bagging is a must if you don't want more resin than is desired. Sanding is the pain in the ass part but the results are worth it. Credit to Eric Hosko for tall tale.
View attachment 1149299View attachment 1149300View attachment 1149301View attachment 1149302

 

[Hosko]

Because the vertical tail is cnc cut i can make tail any height . G001 has a 76" tail while G942 is 72".

 

[Hosko]

After a bit of practice have the weight down to 6.5kgs (14.3 lb)

 

[Jazzenjohn]

I've made quite a few tails by several different methods, all were ugly, but all were very light. In my experience, Tube and fabric tails generally end up being the lightest in practice. My current tube and fabric tail is about 7.5 pounds. It is light because fabric doesn't weigh much and there are few avenues to add useless pounds other than 50 coats of paint. Stressed skin can be very light, but there are limitations and many pitfalls. The biggest are skin thickness and ribs. If you use 8 square feet of horizontal area even the thinnest standard aluminum .016" works out to be about 4 square feet per pound, so 4 pounds for the skin alone on the HS. It's easy to say I'll just use this .030" skin I have laying around as it is only .014" thicker but it doubles the weight. Fabric is mere ounces per square yard (9 sq. Ft.) and doesn't go up much if someone decides to use standard fabric vs ultralight. Glass foam construction is very difficult to get to its theoretical best performance and it is easy to inadvertently make it heavier. They generally look the best though. I've seen some fantastic looking wood tails that were very light but I don't have any experience making them.

 

[jany77]

Agree with John the lightest tail is always aluminum tube usually connected with gussets and pop rivets ,it can be made light when using new oratex covering or just pre sewn dacron just like on quicksilver airplanes .
I tried fiberglass over the foam and all metal tail with the same volume ,both came up to be double the weight ,because aluminum skins are too heavy per sq./f and fiberglass usually needs some finish .
I also made couple tails using thin 3/64 plywood over the foam but also came out too heavy.

 

[J.C.Casabuono]

Sorry, you can do the hand layup between Mylar sheets, and put it over a male mold with the form of the tail. this way you have a good finish after the Mylar removal, and you dont even touch the resin.
After that, you can use foam ribs bonded to this skin to form the tail.