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99lb/45kg primary glider

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Hephaestus

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Hangar beers discussion last night that got me curious.

What we were discussing is an option to get back to "old school" glider training. Students spend a bunch of time waiting around between flights, most of the time getting "busy work". While primary gliders operating as hang gliders don't get logbook time, they could be valuable stick and rudder time. Especially if they could be winch launched.

Canadian rules at times suck. Don't really have an equivalent to part 103 glider class.

However we are allowed 45kg/99lb hang gliders in a pretty much deregulated class.

Eyeballing the Sandlin goat / compact 110, most use the American rules - so they run 30-40lbs heavier.

But the swift hits the target at 100lbs... But at costs approaching 6 figures.

All of them suffer from the 170lb pilot weight issue, pretty sure 210lbs is the new minimum at least in our vicinity.

I don't suppose any of you have put any pen and paper time into a project that might come close? Or have some great thoughts as to how to achieve a 99lb primary glider?
 

Hot Wings

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Even with US weight limits for a pure glider under part 103 we bump up against the weight wall without using complex or $$$ solutions for modern pilots. In the US we have the option of adding vestigial power and using the full #254 limit. Does Canada have a similar option?
 

Hephaestus

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Even with US weight limits for a pure glider under part 103 we bump up against the weight wall without using complex or $$$ solutions for modern pilots. In the US we have the option of adding vestigial power and using the full #254 limit. Does Canada have a similar option?
You could add an engine - and then you're in our ultralight class, which is about your LSA class equivalent.

But the requirement for the ultralight pilot permit then negates any benefit in this particular use.

The aforementioned Swift does make the weight limit, the Archaeopteryx comes close - they're both pushing the performance end of things, which kind of makes me wonder if there isn't a possibility for the tradeoff of performance for weight.

Can also largely ditch some of the teardown abilities as they'd be basically airport based not getting transported. However wings coming off in case of off-airport I think would be a minimum.
 

Victor Bravo

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I have a potentially viable way to accomplish this... I think :)

When I get home later I will put my sketch into this thread. But for the moment, you will have to put up with words-

First, you're going to need a flying wing (either a Backstrom style plank or a Marske Monarch/Pioneer style wing). Ain't no way around it, you can't afford to have a separate tail, tailboom, etc.

I will propose the Marske wing as the basis for three reasons:

1) The increased root chord and higher aspect ratio deliver better pitch damping (the elevator is further away from the CG), which will make launching or towing easier. The increased arm/distance also means that the elevator will have a little less effect messing with the lift distribution and total lift.

2) The Marske wing has separate ailerons and elevator, eliminating the mixer and several of the handling issues with elevons.

3) The Marske wing is known to be very soarable in light lift, lower sink rate, and so will yield more air time per flight.

You're also going to have to use some amount of carbon fiber if you want to meet that weight and still have something that doesn't break easily.

The Marske Monarch is a good start, and represents the kind of flying you want to do, but it is too heavy for sure.

So remove the entire fuselage. Hang the lower part of the pilot seat right under the front face of the spar web. The front spar web is the top half of the seat back Put the skid under the seat itself, attached to the part you want to protect. The pilot's feet rest on the front of the skid. The elevator pushrod and aileron torque tube come forward through the wing, and connect to the stick mounted on the lower inboard edge of the starboard root rib, as a side stick.

Now mount a light fabric covered vertical fin (foam/composite structure) onto a carbon tube. The front of the carbon tube bolts or pins to the rear of the main spar. The part of the carbon tube under the vertical fin sits on top of, and bolts to, the wing rear spar.

Measurable weight savings can be achieved by using tip mounted drag plates for yaw control (connected to the rudder pedals), instead of hinging and increasing the weight of the fin.

The Marske method of building a composite spar will likely have to be used, with the "Graphlite" carbon strips.
 

Hephaestus

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BJC
What am I looking for here?

I have a potentially viable way to accomplish this... I think :)

When I get home later I will put my sketch into this thread. But for the moment, you will have to put up with words-

First, you're going to need a flying wing (either a Backstrom style plank or a Marske Monarch/Pioneer style wing). Ain't no way around it, you can't afford to have a separate tail, tailboom, etc.

I will propose the Marske wing as the basis for three reasons:

1) The increased root chord and higher aspect ratio deliver better pitch damping (the elevator is further away from the CG), which will make launching or towing easier. The increased arm/distance also means that the elevator will have a little less effect messing with the lift distribution and total lift.

2) The Marske wing has separate ailerons and elevator, eliminating the mixer and several of the handling issues with elevons.

3) The Marske wing is known to be very soarable in light lift, lower sink rate, and so will yield more air time per flight.

You're also going to have to use some amount of carbon fiber if you want to meet that weight and still have something that doesn't break easily.

The Marske Monarch is a good start, and represents the kind of flying you want to do, but it is too heavy for sure.

So remove the entire fuselage. Hang the lower part of the pilot seat right under the front face of the spar web. The front spar web is the top half of the seat back Put the skid under the seat itself, attached to the part you want to protect. The pilot's feet rest on the front of the skid. The elevator pushrod and aileron torque tube come forward through the wing, and connect to the stick mounted on the lower inboard edge of the starboard root rib, as a side stick.

Now mount a light fabric covered vertical fin (foam/composite structure) onto a carbon tube. The front of the carbon tube bolts or pins to the rear of the main spar. The part of the carbon tube under the vertical fin sits on top of, and bolts to, the wing rear spar.

Measurable weight savings can be achieved by using tip mounted drag plates for yaw control (connected to the rudder pedals), instead of hinging and increasing the weight of the fin.

The Marske method of building a composite spar will likely have to be used, with the "Graphlite" carbon strips.
Yeah I was pretty much thinking that would be the case. On the more modern composite use.

Only major concern would be they'd want it to fly like a conventional glider. That worries me a bit with some of the flying wing designs.

Half of me wondered if following boku's method (which I'm anxiously waiting an update on) couldn't get some of that weight out of the existing goat wing, a fuselage that's a little more material efficiently designed like Fritz's ranger (with some tweaking) But yeah tailboom ends up eating a chunk of the weight budget.

I'm not sure on the finer points of gliding but - don't think they'd really want to put a student in something high performance, part of that old primary glider idea was you would have to really work hard to get fast enough to kill yourself.
 

BJC

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What am I looking for here?
What I thought you were asking about. Perhaps I misunderstood.
primary gliders operating as hang gliders don't get logbook time, they could be valuable stick and rudder time. Especially if they could be winch launched.
A program that uses an ultralight wing and tail repurposed as a primary glider that can be winch launched to train young kids as unregulated glider pilots. I don’t know the empty weight, but I have seen one, and it looks to be about as light as I would want to fly, excluding an all carbon glider.


BJC
 

proppastie

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Original Carbon Dragon (mostly wood) was 147 lb....Sparrow Hawk (CF) was under the 150 lb limit.....Plans for the Carbon Dragon at the Irish site my signature block
 

cluttonfred

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I’d suggest a two-axis design along the lines of the Skycraft Scout, basically following the Santos-Dumont Demoiselle model. If fact, if you’d find Scout drawings you’d basically just have to remove the engine, move the pilot seat forward and add some sort of forward skid or frame for crash protection. It’s also lovely design with attractive, bird-like lines.

26DE7327-58B2-48B7-B3DE-E626EAF15D00.jpgE63C76AA-8859-41CA-B712-D2E318A94936.jpeg16553B01-956F-46C7-A98B-7538472F7815.jpg

 

Victor Bravo

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A traditional SG-38, LAK-16, or GOAT style primary glider delivers everything you want except for meeting the weight requirement. To meet that weight, you are forced to abandon the traditional. No way around it.

The good news is that the Marske flying wings have a reputation for behaving and handling similar to a traditional airplane/glider. Not exactly the same, but safe, predictable, and not any more difficult to fly. That is the reputation, I have no personal experience. But Jim Marske is a very good guy, cares deeply about the sport of gliding, and has allowed many many pilots of various skill levels to fly the Monarch. So he is in the position to give you an explanation and justification for whether a Monarch-inspired primary glider is suitable for your use.
 

Hephaestus

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What I thought you were asking about. Perhaps I misunderstood.

A program that uses an ultralight wing and tail repurposed as a primary glider that can be winch launched to train young kids as unregulated glider pilots. I don’t know the empty weight, but I have seen one, and it looks to be about as light as I would want to fly, excluding an all carbon glider.

BJC
Yeah, the programs are still there... Lots of them around still. Thankfully.

Question becomes how to do it in the current regulatory environment.

Which gets back to yes - is it a mostly carbon wing, whole new design or what is needed to make the 99lb limit.
The good news is that the Marske flying wings have a reputation for behaving and handling similar to a traditional airplane/glider. Not exactly the same, but safe, predictable, and not any more difficult to fly. That is the reputation, I have no personal experience. But Jim Marske is a very good guy, cares deeply about the sport of gliding, and has allowed many many pilots of various skill levels to fly the Monarch. So he is in the position to give you an explanation and justification for whether a Monarch-inspired primary glider is suitable for your use.
Yeah monarch I was looking at but it starts moving into that slippery enough to get into big trouble category.

Keeping it drag limited to 50mph or so makes really good sense in a training environment.
 

Hot Wings

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Yeah monarch I was looking at but it starts moving into that slippery enough to get into big trouble category
Drag is cheap and light to add.
This is from an old 'what if' of mine similar to this thread, but based on US part 103 and patterned after the Monarch formula with a bit of second generation Lak 16 influence. For a data point SW says what you see weighs about 50 pounds - excluding - the wing.
Marske ish single tube assembly.JPG
 

tdfsks

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The LAK-16 shown in this video is heading in the right direction but its weight is twice the 99 lb weight limit that the OP is looking for.

For me the interesting thing in that video is the winch setup ..... looks like the winch lines are diverted 90 deg suggesting that they might have some sort of arrangement where they have parallel winch lines and one is recovered as the other pulls the glider making for a very efficient operation and little downtime between launches (assuming you had enough gliders).

If fact, if you’d find Scout drawings you’d basically just have to remove the engine, move the pilot seat forward and add some sort of forward skid or frame for crash protection. It’s also lovely design with attractive, bird-like lines.
There were never any drawings of Ron Wheeler's Scout. It was, I think, the first factory finished ultralight in the world. Ron was a sailmaker and he used a lot of ideas from the yachting world. The wings used an extrusion for the leading edge spar not unlike a yacht mast and the sail slid into a groove in the back of the spar.


I think VB is on the right path, provided that the flight handling was representative of gliders the students would fly later. The Mitchell B10 wing was 68 lb (including tip rudders), 34 ft span and 136 sq ft. All wood and a cantilever. That suggests a wing for a Monarch type glider could be made for a similar weight. Add a basic fuselage like on the LAK16 and a rudder framed with aluminium tube and I am sure the weight can be met. I don't think the use of carbon is required as the spar caps in a B10 are small enough that they do not weigh a lot anyway.

The Compact 110 was mentioned above. Did any of these every get completed and fly ? Has anyone seen the drawings ? What did it really weight ?

The original Klaus Hill Superfloater with the metal D box wing weighed just 90 lb and meets the requirements of the OP ? Span 32 ft, Wing area 132 sq ft. L/D = 12 .... which is irrelevant since the glider will generally be under tow and more or less in ground effect.
 
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Jay Kempf

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How to get a lot of wing area for no weight. Always a toughie...

Gossamer Albatross is the inspiration. That was way too fragile. But you can pull back from there some and end up where you want to be.

If you want true 3 axis controls to train with and don't want a flying wing you need a very spindly airframe, wire braced and you need to use as many tension solutions to long strains as possible. See Buckmeinster Fuller for bizarro tension designs.

Carbon fiber is your friend but for a minimum weight but not your friend for minimum cost. Foam is your friend for minimum cost and minimum weight so somewhere between using those two is where the perfect design is.

The old engineering adage: You can have two of the following three things at once.... high quality, low cost, short schedule... Which ever two you pick the budget for the remaining one goes kaflooey...
 

Victor Bravo

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I have not flown either one, but I have to say I suspect the Mitchell Wing is a lot more oddball handling than the Monarch.

Here is the sketch I had promised. This one has a conventional center stick, other versions had shorter control runs.

This one was envisioned for higher performance/lower drag, hence the reclined seating position. This would not nearly be as necessary for the glider being discussed on this thread, and the more upright seating version could be made lighter.

AiRecliner JPG v3 7-23-12.jpg
 

Hephaestus

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Drag is cheap and light to add.
This is from an old 'what if' of mine similar to this thread, but based on US part 103 and patterned after the Monarch formula with a bit of second generation Lak 16 influence. For a data point SW says what you see weighs about 50 pounds - excluding - the wing.
View attachment 99074
Not having even taken a moment on the stress calculations...

a87e4703bb463e184f974ce9dbb97b1f_r3lc.jpg
But that is the marske monarch fuselage. Keeps 3 axis which I think is fairly important when teaching 3 axis... Without the nose on the front (creating drag) - that might be workable in carbon.

Wonder what the 16in wheelbarrow wheel weighs, I can't imagine that's particularly light. With winch launch - a sacrificial kevlar skid may be adequate off a grass field anyway?

As I've said before - carbon isn't super expensive around here - a roll of twill is a lot cheaper landed than any stick of wood from AS&S sadly. Can get west systems epoxy off the shelf 15km up the road.

I have not flown either one, but I have to say I suspect the Mitchell Wing is a lot more oddball handling than the Monarch.

Here is the sketch I had promised. This one has a conventional center stick, other versions had shorter control runs.

This one was envisioned for higher performance/lower drag, hence the reclined seating position. This would not nearly be as necessary for the glider being discussed on this thread, and the more upright seating version could be made lighter.

View attachment 99079
I like that!
 
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tdfsks

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The original wood wing Monarch weighed 250 lb empty. Span was 42 ft and wing area 185 sq ft. It would be a big ask to reduce the weight to 99 lb without reducing the span and area.

I have always felt that Marske didn't encourage the popularity of his designs by the way that they were built and that (in my opinion) continues today with the use of the carbon rods for spars. If the Monarch fuselage was built from wood and the wing was a simple all wood design, I am sure more would have been built.

Another glider for consideration here is the ULF-1 ... it is 101 lb empty. I have the plans for this glider and it goes to extreme lengths to save weight ..... but it is clear looking at the plans that this would not have the durability for use as a training glider.
 

tdfsks

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Here is the sketch I had promised.
VB, this is not a bad concept.
Do you think the lower pilot position under the wing in the Monarch contributes to stability by pendulum effect of the pilots weight ? I think it does ....
Also, depending on where you located the spar, you might need to use a small amount of forward sweep.
 

Victor Bravo

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The Marske wing definitely uses a slight forward sweep for CG.

If it were necessary to increase the dihedral a few degrees, to balance out moving the pilot upward, that's no big deal.

I am aware that the stock Monarch was heavy. I was never suggesting anyone build a stock Monarch and try to get it down to 99 pounds. I was suggesting that the size, shape, and airfoil of the Monarch could be used, and the wing structure re-designed to come in at 70 pounds, then eliminate 75% of the Monarch fuselage.

The Monarch is also strut braced, and if you are moving the pilot (and keel) upward like this then the struts would have to go away too. This is an entirely new design, but it makes use of some things that Marske got right.

I don't think it is possible without liberal use of the carbon strips. Or a filament wound carbon windsurfer mast tube for the spar, with a vertical web somehow inserted into the tube.
 
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