Does anyone know the forces on a glider with wing covers, that's tied-down facing directly
into the wind? I'm guessing the lift from the wing is substantially reduced, but the
rearward force is higher. If I'm right, a covered glider would be safe with much lighter
ropes/straps.

I've seen makeshift "spoilers" tied to the top of the wing on a tied down glider. Anyone
know how effective that is in reducing the lift from the wind? Or from having the glider
spoilers extended instead?

--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Sunday, 1 May 2022 at 17:14:32 UTC+1, Eric Greenwell wrote:

Does anyone know the forces on a glider with wing covers, that's tied-down facing directly
into the wind? I'm guessing the lift from the wing is substantially reduced, but the
rearward force is higher. If I'm right, a covered glider would be safe with much lighter
ropes/straps.

I've seen makeshift "spoilers" tied to the top of the wing on a tied down glider. Anyone
know how effective that is in reducing the lift from the wind? Or from having the glider
spoilers extended instead?

--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications

I can't give you numbers but some years ago in Scotland I watched a Duo with Jaxida covers on, and facing into wind lift both wing tips that were each weighed down with 2 x big water barrels and then roll backwards off the stands.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Sunday, May 1, 2022 at 12:14:32 PM UTC-4, Eric Greenwell wrote:

Does anyone know the forces on a glider with wing covers, that's tied-down facing directly
into the wind? I'm guessing the lift from the wing is substantially reduced, but the
rearward force is higher. If I'm right, a covered glider would be safe with much lighter
ropes/straps.

I've seen makeshift "spoilers" tied to the top of the wing on a tied down glider. Anyone
know how effective that is in reducing the lift from the wind? Or from having the glider
spoilers extended instead?

-- A loose cover will lift into a highly cambered surface over half the chord and then

collapse around 50% chord as the flow separates; just what the Cl of this could be measured
but not easily. It might be higher than the wing section at zero AoA. I think spoilers are
a good precaution if you must face the wind.
JMF

Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Sunday, May 1, 2022 at 9:38:01 AM UTC-7, jpg...@gmail.com wrote:

On Sunday, 1 May 2022 at 17:14:32 UTC+1, Eric Greenwell wrote:

Does anyone know the forces on a glider with wing covers, that's tied-down facing directly
into the wind? I'm guessing the lift from the wing is substantially reduced, but the
rearward force is higher. If I'm right, a covered glider would be safe with much lighter
ropes/straps.

I've seen makeshift "spoilers" tied to the top of the wing on a tied down glider. Anyone
know how effective that is in reducing the lift from the wind? Or from having the glider
spoilers extended instead?

--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications

I can't give you numbers but some years ago in Scotland I watched a Duo with Jaxida covers on, and facing into wind lift both wing tips that were each weighed down with 2 x big water barrels and then roll backwards off the stands.

I was surprised to learn that most owners leaving their covered gliders outside at the Midland Gliding Club (my summer flying location) secure them by using wing stands alone without tie-downs. Many local fliers commented as I pounded a half-dozen
stakes around mine that this was unnecessary! This was after a career of surviving Arizona and New Mexico thunderstorm gust fronts.

Mike

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On a couple of occasions, I've seen covered gliders lifted off and flying in their tiedowns at Minden. The wing covers were ballooned up over the wing. They have also broken free to flip over and crash into other aircraft, and in one case punched a hole
into a trailered glider. I recommend sewing a span-wise sleeve in the wing cover. The sleeve being in 4' sections to each accept a standard length of foam pipe insulation to form a full span spoiler.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Monday, 2 May 2022 at 18:03:02 UTC+1, bumper wrote:

On a couple of occasions, I've seen covered gliders lifted off and flying in their tiedowns at Minden. The wing covers were ballooned up over the wing. They have also broken free to flip over and crash into other aircraft, and in one case punched a

hole into a trailered glider. I recommend sewing a span-wise sleeve in the wing cover. The sleeve being in 4' sections to each accept a standard length of foam pipe insulation to form a full span spoiler.

If I leave my glider out which I would not if the weather forecast was bad,I take the tips off ,its 18m so the tips are quite long4M? they don't weigh much and I can easily fit them on my own.I don't know if it helps but I think the reductions in lift
and profile help reduce the chance of damage, and I still have the advantage of ease of rigging.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)