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By Ground Slammer
#402348
Red-I have not got that much airtime on my Fledge and have been following your posts with a good deal of welcome. What you express as attributes you liked about your Fledge have been noted and appreciated. The spiral stability is now on the agenda. I always had a negative attitude about too much spiral stability- it comes from 2 axis RC's of mine. I hate it when I am off in co-ordination of a turn and before I can compensate-- the glider rolls out of the turn.

As you understand the planned future of the craft has me looking at reducing the dihedral so the craft is has less crosswind taxi rollover risk. I understand that with spoilerons I'll still need weight shift and some dihedral or the roll rate will be too slow. You also understand that wingletts will exacerbate cross wind taxi rollover. I know I'm preaching to the choir about this with you.

I also wish to do as little re-engineering as possible. The hang glider will be back engineered from the Quicksilver MX. The leading edge, the diagonal struts, the tail struts, the rudder, all MX. The compression struts will be ready to outer sleeve as the crafts weight increases and the root tube will be 1 and 5/8ths with saddles so all the mounting points are the same as when I switch to 2 inch square tube latter. I don't want to bastardize a hang glider into a motor glider, rather start with the proven motorized Quicksilver and back engineer to the hang glider. As for your comments on the Fledge and more, keep it up I'm listening more than you might think I am.

Raquo-I am only planning on testing my sail innovations and will run about 40 square foot of wing area. My racks will be centered on the wagons support pillars. The racks are good for more than 200 pounds so I'll be able to go 2x stall speed with max angle of attack, faster at lower angles. The racks will be between the wagons axles and biased toward the front. To static check your wings load resitance most home-builders use the sand bag method. Because I'm back engineering from a Quicksilver that is designed to have a gross weight of 500 pounds plus, and my hang glider phase craft will be about 240 pounds gross-more than 10 g's of strenght -more than enough.
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By red
#402350
Ground Slammer,

Just a note: I have met a lot of HG pilots who think a Fledgling is turned by the tip rudders only. To turn efficiently, especially in thermals, it is not useful to use the rudders. To initiate a turn, sure, pull one rudder, get a bank going, but then release the rudder. All turning beyond that first bank can (and should) be done by pitch alone. Fly too fast, and the glider levels the wings. Fly too slowly, and the bank gets steeper. Circling in thermals, when done in this manner, is almost effortless. You may occasionally need some top rudder to avoid over-banking in a turn, and to roll out level on course.
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By Ground Slammer
#402351
Agreed-bank it-crank it-and if the spiral stability is right, it should need only tads of roll input beyond that.
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By red
#402352
Campers,

While we are brainstorming on the next generation of ultralight gliders, I have a concept in mind, for me. I have a bum leg that does not get better with age, so I can see the day coming when feet as my landing gear will not be reasonable.

What I want is basically an ultralight trike. The wing can be an ATOS, or maybe an updated Fledgling, topless, with two struts on each wing and modern wing spars, built to handle that design. The trike fitting on the keel would be a three-axis ball fitting, to handle any crosswinds; just pivot the glider directly into the wind, set the AOA, and roll straight down the runway to launch. Allow the glider to "weathervane" into the relative wind direction, as ground speed increases.

The thrust unit, if any, would be electric, as soon as better (safer) batteries happen. It would be mounted as seen below, on the trike rear spar, slightly above the pilot. The prop shaft (or the engine mount) would be long enough for the prop to clear the keel and the pilot's feet. I'd want a folding prop, of course. The "harness" would be a basket assembly with the wheels, which can carry the prone pilot comfortably. The pilot basket itself can be covered with sealed biplane fabric, like a skinny dirigible in appearance, for streamlining purposes. Starting reference:

http://www.electraflyer.com/trike.php

Image
User avatar
By Ground Slammer
#402362
My own pursuit started when I saw a video of that bird you posted. The camera was mounted on the keel, pointed at the pilot. One thing that was obvious -- anyone with a bit of seated time would find it intuitive to fly. The electric motor with it's instant on and no restart issues said "this is the ideal motor for an ultralight motor glider." I also think fared in pod too. Rag wing or fixed wing--- I'd have to buy a rag wing, but a QS I've built a few. I too am getting older and I don't "need" to use my own legs. If I can save my body with landing gear--- well I'm on it.

PS I think I've found a flaw with my trailing edge idea :cuss: - looks like the Fledge1/Kasper Wing method, with a really wide leading edge pocket.
By Lazypilot
#402363
I was considering your desire for a sharp trailing edge. If the sail has let's say 1 foot of extra material behind the round tube rear spar you could slide in a stiffener made from two layers of the Mylar now used as leading edge definers in flex wings, glued together at the trailing edge. This would stiffen that area, reducing flutter, and define it nice and sharp. Strategic trimming of the Mylar could be done to affect small changes to camber and reflex, for trimming out a turn, for example.

If crosswind handling is a concern, slack in the upper wires would allow for less dihedral or even some anhedral. But that might be a problem in turbulence.

Reverse engineering the Quick is a smart idea. I'd like to get a set of plans for the Skypup and re-engineer that design into a glider, adding a rear spar so that a different airfoil could be used. Or just use the plans as a guide for determining material thicknesses and whatnot for a new design. There's a lot of things to contemplate here, maybe more than my poor abused old brain can do. But I'm thoroughly enjoying the day dreaming, that's for sure.
User avatar
By red
#402366
Ground Slammer wrote:
Sat Feb 17, 2018 8:42 pm
I think I've found a flaw with my trailing edge idea :cuss: - looks like the Fledge1/Kasper Wing method, with a really wide leading edge pocket.
Ground Slammer,

I am all in favor of the Fledgling-1 wing design. Klaus Hill was a genius, if I ever met one. So much so, that when Manta made the F-2, the original F-1 gliders were able to outrun the F-2 gliders easily. "They did it wrong," Klaus told me, laughing. Manta ended up using a straight 1" tip rib on the F-2, where the F-1 still carried camber and reflex. Even then, the F-2 was only marginally faster than the F-1. Klaus was still kinda pissed, actually, and so he built the Voyagers as the "real" F-2 design. The Kasperwings were contemporary with the Fledgling-1 designs.

Now I am certainly not Klaus, but I believe the design of the F-1 wing would allow for pivoting a control surface from that strong rear spar, with a single-surface trailing edge all across the glider. When Richard Cheney built the SuperFloaters, he put "hinges" into the 1/2" ribs, about 8" from the trailing edge, to allow for the control surfaces to deflect as needed. The trailing edges of the wings on that glider looked exactly like any single-surfaced glider, until somebody moved the control stick left or right. Smooth move. 8)
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By TjW
#402367
The Cheney SuperFloaters work great, but there's all those fiddly bits to build. A standard aileron that has some stiffness just needs one bellcrank. The SuperFloater has... I don't remember, but quite a few. I admire the light build, but there's a lot of little parts to cut and drill and rivet.
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By Ground Slammer
#402369
My fist thoughts on the soft TE was to put a grommet on either side of the sails TE at the edge of the batten pocket. Make the rib/batten stick out so my I can get about a 45 degree angle on the bungee cord-- so I'm pulling back and inwards the question is; should I scallop between battens or can I get away with strait?

On that wing tip error on the Fledge 2- not only does it contribute to tip stall, it has a piss poor profile drag co-efficient. That wing would have gotten 12 to 1 if it had the camber continued to the tip.
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By red
#402370
Ground Slammer wrote:
Sun Feb 18, 2018 1:14 pm
My fist thoughts on the soft TE was to put a grommet on either side of the sails TE at the edge of the batten pocket. Make the rib/batten stick out so my I can get about a 45 degree angle on the bungee cord-- so I'm pulling back and inwards the question is; should I scallop between battens or can I get away with strait?
Ground Slammer,

You should know, the RC airplane hobby shops sell Carbon Fiber "sticks," pre-made to various shapes and sizes. You can buy CF "planks" or round CF rods in many small sizes, there. You can slip a thin CF stick between the needle holes, between the sail layers, down the length of zig-zag stitching. If the TE hem is large enough, slide the stick inside the folded hem at the trailing edge. Flexwing pilots do this trick to eliminate sail flutter between ribs at high speeds. It's a lot cheaper than adding the weight of "speed ribs" to a poorly made flexwing sail.

Planks will support straight TEs. Rods will support scalloped TEs. So it's your choice, but I'd favor the straight TEs for the added area.
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User avatar
By Ground Slammer
#402371
I'd much rather have strait, easier to make and more aerodynamically efficient. I'm unfamiliar with the carbon plank but it sounds good. Would it be best to put it in the crease of the TE and then sew, or make it so it is inserted after sewing?
User avatar
By red
#402373
Ground Slammer wrote:
Sun Feb 18, 2018 2:31 pm
I'd much rather have strait, easier to make and more aerodynamically efficient. I'm unfamiliar with the carbon plank but it sounds good. Would it be best to put it in the crease of the TE and then sew, or make it so it is inserted after sewing?
Ground Slammer,

It's easier to add the CF sticks after sewing. Even with sails where the makers never considered having CF sticks, it's easy to remove a few stitches near the rib and slide the sticks into place. You can lock them in place if you want, just hand-sew a few new stitches back into the old stitch holes. Easy-peasy.
User avatar
By TjW
#402374
Or you could use the flip tips as used on HG sails. You end the applied batten pocket a small distance away from the trailing edge, and hem the trailing edge, putting a lockstitch on either side of where the rib is. This makes a little pocket to seat the rib in. Chordwise tension is adjusted by screwing the flip tip in or out.
User avatar
By Ground Slammer
#402396
If I go with tubular battens I think the flip tip is the way to go. I'm going to first try flat wooden ribs like the original quicksilver. If the woodies go in without jamming then I think they will have certain advantages. I'll find out when I make the mock up sail.

What I want to ask you guys about is how I am going to get the compression struts and diagonal struts out of the leading edge pocket. The one example that I know of is the Weedhopper. I would like to ask if any of you know of any other light aircraft that has the compression struts come out of a large leading edge pocket. I still need to interface with Weedhopper people to get the details of the sail work associated with passing the strut out of the pocket. I never gave that much thought when I've seen Weedhoppers in the past. None of the online photos I've seen have adequate resolution. Yet if there are other aircraft that have the same issue ( passing the strut out of the leading edge pocket) other than Weedhopper let me know.
User avatar
By red
#402399
Ground Slammer wrote:
Wed Feb 21, 2018 1:49 pm
What I want to ask you guys about is how I am going to get the compression struts and diagonal struts out of the leading edge pocket. . . . I still need to interface with Weedhopper people to get the details of the sail work associated with passing the strut out of the pocket.
Ground Slammer,

Look at any double-surface HG. Where the sidewire exits the sail, they just hot-knife an opening. The same is true for the Fledgling-1 compression struts. Rigid wings have very little force on the sail material, there. There is no special sailwork involved, unless you want to sew a 9-ounce reinforcement patch inside the sail where the wire or strut comes through. In that case, stick the rear seam of the double surface to the two-sided tape on the main body of the sail, pin it with straight pins, and sew the rest of the sail normally (except for that rear seam). Assemble the glider, determine where wires or struts will pass through the sail, then mark and hot-knife the holes where needed. When everything fits, remove the sail from the glider, open the rear seam of the DS, and sew in the reinforcement patches. Then you can sew up the rear seam of the DS, removing the pins as you sew.

I would need to have some serious concerns about sail strength there, before I decided on adding reinforcement patches around the holes in the sail, at least until the first units are flying.

Assuming that you want a sailcloth glider, if you plan to make more than one glider, I'd suggest making sail patterns from stiff (0.030" or 0,762mm minimum) Mylar sheet, which will be fairly stable in dimensions. The best sailmaker I know uses thin stainless steel sheets to make his templates. Once you know where the holes need to go, add those locations of the reinforcement patches to the the templates. Now if you have a CNC sail cutting table available, your templates will be digital, so add the patch locations to the template files.

Best wishes . . .
By Lazypilot
#402426
file:///C:/Users/User/Desktop/tip%20feathers.pdf

This is good stuff. I like the idea of using the primary feather trick to boost the span factor. Allows for a relatively short span glider, which saves weight.
User avatar
By red
#402430
Lazypilot wrote:
Mon Feb 26, 2018 8:24 am
file:///C:/Users/User/Desktop/tip%20feathers.pdf
This is good stuff. I like the idea of using the primary feather trick to boost the span factor. Allows for a relatively short span glider, which saves weight.
Lazypilot,

Umm . . . You posted a link to a file on your computer , there. If you want anybody else to see it, post the .PDF as an attachment, or post it on a server someplace and just post the link to that, here.
By Lazypilot
#402448
Woops a daisy! Here it is:

http://jeb.biologists.org/content/180/1/285

Wingtip aerodynamic devices can boost the effective aspect ratio, allowing a glider to have a relatively short wingspan, which is lighter to build than a long span wing.

And although a good glide at low speed is a must have, I think most folks spend most of their flying hours boating around in the lower half of the speed range of their glider. So if a lightweight short span glider can get a boost from these tip feathers we need to try them out.

Seems like spanwise tip feather sails can be easily sewn into a Hg sail, tapered fiberglass or carbon fishing pole type battens inserted to stiffen them. If the load builds up too high they would flex upward and relieve bending loads at the spar. This will allow a lighter construction for that spar. Think of those advertising banners with the curved tips, they could be made like that, with inserts that provide reflex and camber so they can find an optimum AoA.

Airplanes often gain weight as they are developed, requiring a bigger motor, which needs bigger gas tanks, and beefing up the structure to handle the added weight and power. It's like a snowball rolling downhill.

But the opposite can be had, the designer has to weigh every decision carefully, thinking ahead to see if a part can be made lighter, which in turn may allow another part to be lighter, and we like that snowball effect.

This is one reason I likely won't use a swept wing. A straight wing spar is simpler, washout or in won't have effects on pitch, the weight saved by not having torsional resistance things like sprogs can be used to build a tail or canard surface.

The weight and cost of a VG can be used to make the glider so that muscle effort can be applied to directly warping the glider, as opposed to just placing your weight more on one side than the other, and having just the right tension on the sail so it will respond to that. You know it well: Shift, Wait.

Hang gliders, as we know them, are actually a lot more complex than would be a simple straight winged glider with a bird like tail, even if that glider can be twisted enough to have sports car handling.

A simple lightweight glider that is maneuverable and can be built inexpensively with common materials by the average Joe is a thing our hobby could use. Serious designers will continue their quest for the foot-launched sailplane, and that's a good thing, but I believe that the greater percentage of us will actually prefer a good low end machine that doesn't break the bank and is not intimidating to launch in no wind.
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By Ground Slammer
#402523
I got some feedback on the Weedhopper strut. If I'm allowed a link here is a good photo http://ulflyer.com/weedhopper/images/10 ... up_JPG.htm casual observers may miss an important part. The length of the opening is actually shorter than what it would take for the tube to fully pass through without a small amount of the compression strut-just past the opening- to have the top of the compression strut tube press on the bottom of the sailcloth. This places the patch out of plane with the rest of the sail bottom-it causes less flow over the patch and tensions the cloth. I like this simple and easy to sew option.
User avatar
By magentabluesky
#402528
Use your imagination and apply 50 years of evolution in the Platz design to a modern hang glider.

Platz Glider

In the 1920’s the Platz Glider weighed 40kg/88lbs.

There are advantages to a jib arrangement in a wing plan form. The slotted wing can achieve greater lift coefficients reducing landing speeds. Coupled to a VG system, large variations in square footage could be obtained in overlapping wings expanding the wing loading/speed range.

The jib wings could be integrated with a mechanical hang loop lever system for control in keeping with the current control bar standard widely used today.

The drawbacks are complexity and keeping the weight down.

MK1 Splitwing Circa Tony Prentice
Pictures MK1 Splitwing
Attachments
Platz Glider.JPG
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