final glide estimates

toad wrote:
This is the basic method to set maneuvering speed:

The Maneuvering Speed is the minimum speed at which the wing can
produce lift equal to the design load limit. (in positive G's) Below
this speed the wing can not produce enough lift to overstress the
aircraft, no matter what angle of attack is used.

Maneuvering speed assumes max gross weight. If you're flying lighter
the wing can make enough lift to break.

Shawn

In article ,
Stefan wrote:

John Galloway wrote:

A quick scout through the BGA datasheets seems to show
a trend that for modern single seaters the rough air
and manouevring speeds are the same

Yes, but I don't believe it's really for technical reasons. I rather
suspect that the manufactorer defines it deliberately that way to keep
things simple for the pilot. (Quick test: Do you know whether the green
arc defines maneuvring speed or rough air speed?)

Manouevring.

Rough air places lower loads on a structure than do extreme control
deflections, so rough air speed will always be the same as or higher
than manouevring speed, never lower.

--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------

John Galloway wrote:
Yes 119 knots for both rough air and VNE for the Standard
Cirrus with a manouevring speed of only 81knots.

I notice the Hornet has it reversed: Rough air = 75 knots; maneuvering =
81. It's hard to believe the Hornet might be in trouble at 76 knots and
the Cirrus could blast on past at 119 knots!

A quick scout through the BGA datasheets seems to show
a trend that for modern single seaters the rough air
and manouevring speeds are the same but for some older
singles and current deep spar two seaters the rough
air is higher. I don't know how the speeds are determined.

http://www.gliding.co.uk/bgainfo/tec...datasheets.htm




--
Change "netto" to "net" to email me directly

Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"

Shawn wrote:
toad wrote:
This is the basic method to set maneuvering speed:

The Maneuvering Speed is the minimum speed at which the wing can
produce lift equal to the design load limit. (in positive G's) Below
this speed the wing can not produce enough lift to overstress the
aircraft, no matter what angle of attack is used.

Maneuvering speed assumes max gross weight. If you're flying lighter
the wing can make enough lift to break.

Shawn

This is true, at lighter weights the maneuvering speed goes down, since
the airframe is only strong enough for X g's.

Toad

Bruce Hoult wrote:
In article ,
Eric Greenwell wrote:

You're right, John - I should've checked my manual. Does anyone know how
the Rough Air limit is determined? Is it always the same as the
maneuvering speed limit in gliders?

No it's not. Our Janus, for example, has maneuvering at 92 knots, but
both rough air and Vne at 119 knots.

That seems to suggest the pilot can damage the glider, but turbulence
cannot. Perhaps that's not unreasonable, given the very low Vne,
suggesting the flutter issues were not handled as well as the airframe
strength.

--
Change "netto" to "net" to email me directly

Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"

Shawn wrote:
toad wrote:
This is the basic method to set maneuvering speed:

The Maneuvering Speed is the minimum speed at which the wing can
produce lift equal to the design load limit. (in positive G's) Below
this speed the wing can not produce enough lift to overstress the
aircraft, no matter what angle of attack is used.

Maneuvering speed assumes max gross weight. If you're flying lighter
the wing can make enough lift to break.

So, for gliders, the flight manual figure only applies if you are
carrying full water ballast, and you are supposed to guess at what is
when the glider is unballasted?

--
Change "netto" to "net" to email me directly

Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"

Eric Greenwell wrote:
Shawn wrote:

toad wrote:

This is the basic method to set maneuvering speed:

The Maneuvering Speed is the minimum speed at which the wing can
produce lift equal to the design load limit. (in positive G's) Below
this speed the wing can not produce enough lift to overstress the
aircraft, no matter what angle of attack is used.


Maneuvering speed assumes max gross weight. If you're flying lighter
the wing can make enough lift to break.


So, for gliders, the flight manual figure only applies if you are
carrying full water ballast, and you are supposed to guess at what is
when the glider is unballasted?

No, just calculate it by taking the square root of the mass/max gross
and multiply that by Va, in the cockpit, in rotor, while dropping below
glide to the nearest safe field.
Simple!

The physics argument for Va decreasing with lower mass makes sense.
However, the legal argument for what maneuvering speed should be used
would support the notion of a constant Va at all weights.

Shawn

Andy Blackburn wrote:

0018 and .0022 seconds longer respectively - I think
we can safely call that false precision.

Hi Andy,

Yes. Of course you are right. Thanks for running the check.

Regards,

-Doug

Are you sure they would not use a worst case scenario?

Paul

Shawn wrote:


Maneuvering speed assumes max gross weight. If you're flying lighter
the wing can make enough lift to break.

Shawn

Are you sure they would not use a worst case scenario?

Paul

Shawn wrote:


Maneuvering speed assumes max gross weight. If you're flying lighter
the wing can make enough lift to break.

Shawn