Spoiler placement and design.

Can anyone provide a site or advice on placement a details of construction and
design of spoilers?

Dan, U. S. Air Force, retired

"B2431" wrote in message
...
Can anyone provide a site or advice on placement a details of construction
and
design of spoilers?

Dan, U. S. Air Force, retired

What do you want the spoilers to do? Glide path control like a sailplane or
slow an airplane down to flap/gear extension speed? If the latter, look at
some Mooneys with speed brakes. If the former, visit a gliderport. There
are lots of variations.

One thing to keep in mind is that spoilers spoil the lift in a way that
redistributes it spanwise towards the wingtips. On sailplanes, this can
reduce the wing ultimate load factor from, say 5.5G to 3G - not a good thing
if you are recovering from a dive.

Some people have even tried them as alternatives for ailerons - lots of
issues with this.

Bill Daniels

Some people have even tried them as alternatives for ailerons - lots of
issues with this.
USN EA-6B and A-6 (series) are good examples and in this case are called
"flaperons".


Larry
AECS (AW/SW/MTS)
Disabled Combat Veteran
USN Retired

20 years of Navy in my rear view mirror
and getting further away every day ;-)




"Bill Daniels" wrote in message
news

"B2431" wrote in message
...
Can anyone provide a site or advice on placement a details of
construction
and
design of spoilers?

Dan, U. S. Air Force, retired

What do you want the spoilers to do? Glide path control like a sailplane
or
slow an airplane down to flap/gear extension speed? If the latter, look
at
some Mooneys with speed brakes. If the former, visit a gliderport. There
are lots of variations.

One thing to keep in mind is that spoilers spoil the lift in a way that
redistributes it spanwise towards the wingtips. On sailplanes, this can
reduce the wing ultimate load factor from, say 5.5G to 3G - not a good
thing
if you are recovering from a dive.

Some people have even tried them as alternatives for ailerons - lots of
issues with this.

Bill Daniels

"Larry" wrote in message
...
Some people have even tried them (spoilers) as alternatives for
ailerons - lots of
issues with this.
USN EA-6B and A-6 (series) are good examples and in this case are called
"flaperons".


Well, I can't argue with what they're called on those aircraft, but for
sailplanes, "flaperons" usually refers to trailing edge devices that go up
and down together to act as flaps, and differentially to act as ailerons.
OTOH, you can generally get a good argument going as to whether the glide
path control is a "spoiler" or "dive brake".
Let's not go there.

Tim Ward

Tim Ward wrote:

USN EA-6B and A-6 (series) are good examples and in this case are called
"flaperons".


Well, I can't argue with what they're called on those aircraft, but for
sailplanes, "flaperons" usually refers to trailing edge devices that go up
and down together to act as flaps, and differentially to act as ailerons.

And to confuse matters more, (on the A-6, anyway,) the
flaperons only worked asymmetrically (i.e. like ailerons)
when airborne, and worked symmetrically (like spoilers)
and asymmetrically on the ground.

Dave 'three up, stab shifted' Hyde

"Bill Daniels" wrote in message
news

"B2431" wrote in message
...
Can anyone provide a site or advice on placement a details of
construction
and
design of spoilers?

Dan, U. S. Air Force, retired

What do you want the spoilers to do? Glide path control like a sailplane
or
slow an airplane down to flap/gear extension speed? If the latter, look
at
some Mooneys with speed brakes. If the former, visit a gliderport. There
are lots of variations.

One thing to keep in mind is that spoilers spoil the lift in a way that
redistributes it spanwise towards the wingtips. On sailplanes, this can
reduce the wing ultimate load factor from, say 5.5G to 3G - not a good
thing
if you are recovering from a dive.

Some people have even tried them as alternatives for ailerons - lots of
issues with this.

Bill Daniels


The Taylorcraft L-2M Grasshopper has wing spoilers, designed to kill lift.

On the subject of drooped ailerons and flaperons, I was just looking at an
Aztec with a Robertson STOL kit installed. The only mod I could see was
maybe a dam on the wing. I asked the IA where the hell the mods were, and
he said that the ailerons were drooped (30 degrees?) for takeoff. It was
supposed to get off in 700 feet, he said.

Larry Smith wrote:
"Bill Daniels" wrote in message
news
"B2431" wrote in message
...

Can anyone provide a site or advice on placement a details of

construction

and

design of spoilers?

Dan, U. S. Air Force, retired

What do you want the spoilers to do? Glide path control like a sailplane

or

slow an airplane down to flap/gear extension speed? If the latter, look

at

some Mooneys with speed brakes. If the former, visit a gliderport. There
are lots of variations.

One thing to keep in mind is that spoilers spoil the lift in a way that
redistributes it spanwise towards the wingtips. On sailplanes, this can
reduce the wing ultimate load factor from, say 5.5G to 3G - not a good

thing

if you are recovering from a dive.

Some people have even tried them as alternatives for ailerons - lots of
issues with this.

Bill Daniels



The Taylorcraft L-2M Grasshopper has wing spoilers, designed to kill lift.

On the subject of drooped ailerons and flaperons, I was just looking at an
Aztec with a Robertson STOL kit installed. The only mod I could see was
maybe a dam on the wing. I asked the IA where the hell the mods were, and
he said that the ailerons were drooped (30 degrees?) for takeoff. It was
supposed to get off in 700 feet, he said.



My 2 cents worth there are 3 aircraft that used Spoilers for Roll
controll like they should be. 2 of them were Northrop designs, the P-61
and the C-125, and the other one is the Grumman S-2. They used a mixture
of Spoilers and a small aileron at the tip for roll control. I talked to
a WWII Pilot whoi flew a P-61, He said it was a blast to fly, as long as
you didn't have a nose wheel collapse or land with the gear Up and the
engines running. The rummor was you wound up with a prop blade throw the
cockpit where the pilots legs were.
Bill Higdon
Bill Higdon

My 2 cents worth there are 3 aircraft that used Spoilers for Roll
controll like they should be. 2 of them were Northrop designs, the P-61
and the C-125, and the other one is the Grumman S-2. They used a mixture
of Spoilers and a small aileron at the tip for roll control. I talked to
a WWII Pilot whoi flew a P-61, He said it was a blast to fly, as long as
you didn't have a nose wheel collapse or land with the gear Up and the
engines running. The rummor was you wound up with a prop blade throw the
cockpit where the pilots legs were.
Bill Higdon
Bill Higdon

Mitsubishi MU-2. A killer, and a special rating to fly it. No
ailerons at all. An old pilot with experience in the type told me that
on an IFR approach in rough air the airplane would lose altitude
rapidly when the pilot tried to keep the wings level. Roll is
controlled by killing lift on the inside wing, and there is no
compensating lift on the other, so the net result is a descent when
the spoilers are busy.
The Helio Courier uses them for low-speed roll control in conjunction
with ailerons.

Dan

"Dan Thomas" wrote in message om...

Mitsubishi MU-2. A killer, and a special rating to fly it.

What rating would that be? No FAA type rating is required, although
type specific training is advisable as it is a little quirky compared to
smaller twins.

IFR approach in rough air the airplane would lose altitude
rapidly when the pilot tried to keep the wings level.

Also fun when you lose an engine. Trying to use the spoilers to keep her
straight really eats into the performance. The roll-trim which are actually ailerons
out on the outboard flaps should be used instead.

Earlier, (B2431) wrote:

Can anyone provide a site or advice on placement a details of construction and
design of spoilers?

What I'd recommend:

Go visit a gliderport and look at the spoilers and airbrakes fitted to
various gliders.

If you like the look of the hinged panels fitted to Schweizer gliders
(except SGS 1-35, which uses flaps), just copy what you see there.
There's not much to the system that you can't see; and the loads ought
to be pretty easy to reverse-engineer from the sizes of the panels,
fittings, hinges, metal guages, and performance numbers.

If you like the look of the airbrakes fitted to most european
composite sailplanes, your best bet is either find a broken-open
example or to look up the manufacturer's service bulletins on the Web.
For example, see the airbrake work instructions on the bottom of this
page:

http://www.solairecanada.com/technotes.htm

I'm not an engineer, aero or otherwise, so I adopted a pretty
simplistic approach to sizing the components of the airbrakes on my
project. What I did was to start with the assumptions that my glider
would glide at about ~10:1 at Vne, and that the airbrakes would
conform to JAR-22 for aerobatics and keep the speed at or below Vne in
a 45-degree dive.

Since I know the weight of the aircraft and its glide angle in both
conditions, it's a simple sine function to find the total drag in each
condition. The drag difference between the two conditions must be due
to the airbrakes. So I size the airbrake mechanicals to support the
resulting drag, plus about 50% for safety margin.

That might not be the best way to approach the problem, but when I
work through the numbers, I end up with mechanical components of about
the same size and arrangement as I see on the European racers.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com