aerobatic power to weight ratio

On Aug 5, 6:20 am, More_Flaps wrote:
On Aug 5, 11:47 am, Dudley Henriques wrote:

Capt. Geoffrey Thorpe wrote:
B. Control would be a problem. Hanging from the prop results in torque
rolls. Airplanes don't have tail rotors or cyclic control over the
propeller.

A VERY effective demonstration of this can be done in a P51. You start
from slow flight with the prop all the way up and slowly begin
increasing angle of attack and feeding in more MP as needed to hold
altitude. Sort of like any entry into a slow flight back side scenario.
As you do this you will need more and more right aileron. You will reach
a point where aileron can't hold it any longer and the airplane will
torque roll on you.
It's a VERY effective technique for demonstrating how NOT to get in high
angle of attack/slow airspeed/high power situations :-))
--

I understand the reasoning/description here, but how/why do model
planes do it so well?

Cheers

Many models often have out of scale control surfaces

More_Flaps wrote:
On Aug 5, 11:47 am, Dudley Henriques wrote:
Capt. Geoffrey Thorpe wrote:
B. Control would be a problem. Hanging from the prop results in torque
rolls. Airplanes don't have tail rotors or cyclic control over the
propeller.
A VERY effective demonstration of this can be done in a P51. You start
from slow flight with the prop all the way up and slowly begin
increasing angle of attack and feeding in more MP as needed to hold
altitude. Sort of like any entry into a slow flight back side scenario.
As you do this you will need more and more right aileron. You will reach
a point where aileron can't hold it any longer and the airplane will
torque roll on you.
It's a VERY effective technique for demonstrating how NOT to get in high
angle of attack/slow airspeed/high power situations :-))
--

I understand the reasoning/description here, but how/why do model
planes do it so well?

Cheers


It's in the ability of the ailerons to handle roll inertia. The
propeller on a Mustang for example is a Hamilton Standard 24D50. It's 11
feet 2 inches in diameter and weighs more than a Mother- In- Law! That
monster can create more left turning tendencies than NASCAR. In the
described scenario above, it's simply a battle between the prop and the
ailerons. The prop wins in this case.



--
Dudley Henriques

Superdoof wrote:
Hi,
I've noticed in the videos at www.fulldeflection.com that all the top
aerobatic aicraft, such as the Sukhoi SU-31, Egde 540, Extra 300,
etc., can almost hover.

It seems that within a few years they will be able to climb on power
alone.

Aerobatics will look completely different once that occurs. Can you
imagine Svetlana Kapanina hovering her Sukhoi for a couple of minutes
at 300', then reversing down to an even lower altitude. I can imagine
Peter Besenyei performing the perfect square shaped hover in his Extra
540.

Is this technically feasible, or have the aircraft already reached a
developmental limit ?

Superdoof.


If the trick is done with purely with power it really isn't that
spectacular. Think about what you described above. It can be done today
by a student pilot in a helicopter.

wrote:


Many models often have out of scale control surfaces


RIGHT!

Some of my r/c models had control surfaces with 4 to 8 times, sometimes
more, than a scale model.

True scale r/c models often suffer from serious controllability issues
in ugly attitudes.

This is why r/c pilots are often encouraged to gain serious experience
before moving to true scale warbirds, just like full-size!

"B A R R Y" wrote

True scale r/c models often suffer from serious controllability issues in
ugly attitudes.

This is why r/c pilots are often encouraged to gain serious experience
before moving to true scale warbirds, just like full-size!

Another factor that has not been brought up, is how weight versus wing area,
and HP to weight ratios of models versus full sized aircraft.

Also, the effect of the air is different at scale sizes, which is related
through Reynolds numbers.

Thrust at model sizes is very easy to get way up over the total weight of
the model. Not so easy with full scale.

There is a rule among model builders, but I can't for the life of me
remember what it is named, or exactly the numerical relationship.

Something like "rule of square" or "rule of cube" or "rule of quad" or
something like that. Basically, as I recall, it is that as size double, the
wing area (or weight) is 4 times as much.

I never got into that type of thing, since I am not into the whole accurate
scale model stuff. As long as it is fun to fly, I'm happy. g
--
Jim in NC