RC Micro World Online Magazine - December 2005
Rogallo Wings in Brazil
By: Agusto César Frazatto / John Worth
The Rogallo wing is a design made famous in the USA by its inventor Frank
Rogallo, with whom I worked when we were both with the NASA at Langley
Field, Virginia. It was a pleasant surprise recently when I received an
Email from a new RCMW subscriber in Brazil. He told of work he had been
doing with this design and many variations of it. Here are his words,
slightly edited by me:
Regarding his Simplwingy
The prettiest and simplest form of
a powered Rogallo Wing
The free flight model in this photo was done on the
Summer/2001 and lasted until June/September of 2002. It flew nice during
that time Its dimensions were: 40cm for the lateral longerons and 50cm for
the central one. The skid was the length of the wing, with a movable
cradle on the skid for CG adjustment
Regarding the weight, I never measured it. I just did the model and tried
to fly it, and how it flew! I suppose it was about 50grams (Kenway motor,
U-80 propeller , jack and a 50mAh NiMh battery included). 2 - 3mm
thickness of the bamboo, so as not to break easily (not too thick, not too
thin, especially the skid .
The yellow Wiry RC Rogallo weighs17 grams naked (just
the frame). The altogether model weight (electronics + bamboo sail + 250
mAh Lipo battery): 75 grams. In this close-up photo you can see the
movable battery cradle mounted over the skid, for the CG adjustment. The
wing appears to be servo-tiltable.
The wing longerons are made of bamboo, because it's less flexible than the
iron (music wire) and supports better the lift without bending.
Some facts on a possible RC mode of building for it:
During almost 2 years I tried different approaches on an RC mode of
control regarding "normal design” Rogallos. First, I used the tilting sail
mode, used by Ron Fikes (Palo Alto-California) on his Rogallos in 2001,
but, for a really SLOW fly, it's sail had to be larger, for enough lift at
low speeds. And this led to shifting balance sideways instead of tilting
the sail (which does the same thing of shifting CG laterally for turn
- Still on the ”trike" approach, I tried an "outboard boat" motor type of
movement, vectoring the motor in a pusher way, but this led to a conflict
between the direction of the motor vectoring and the one the air imposed
on the sail, and it failed frequently (motor wants left, sail wants right,
under the action of the same CG fulcrum = disaster!).
- I tried a bigger Simplwingy model, but with fear for damage to the
receiver and servo if they were located in the front position in the
landings, I put them on the rear, and even with the heavy weight of a
350mAh NiCd battery acting on the front position, I didn't reach a balance
with those electronic units located on a very rear position. So I moved
their location to a more medium position, and this led to the conflict I
mentioned above, motor vectoring/sail.
- This led me to a "profane" solution = a fin...and it worked fine! (to
me, Rogallos wings don't use fins ! They are wings, not airplanes with
fins and rudders!)
- But this model suffered a lot of wing interference and I wanted a "home
street flyer" able to do tight curves and be controllable in a medium wind
open air situation! This led me to try the puller motor position for a
firm vectoring of the wing, avoiding an internal CG conflict, and being
able to protect the receiver and servo and at a rear position in the
frame. And it worked really fine! Not just fine but optimum!!!
- For months I've flown it on the parks nearby with a lot of satisfaction.
It was ugly, but how it flew!!! By now it's retired, because of it's heavy
weight and high consuming battery properties.
- All those models were bamboo made, and bamboo has a limitation on it's
lightening: the more you thin it, the weaker it gets. So, for a small and
really light Rogallo, that hasn't a structural frame, I just use
longerons, I've needed to change to a resistant material that didn't
weight too much. This lead me to trials with iron wires, (music wires as
you name them) measuring and weighing similar pieces of different
thickness until I've reached the minirogallo 'Wiry", the unique one I
evolved to fly on my home street (7-8 meters of width) , in a SLOW manner,
and very obedient to control.
- It's control is achieved by the vectoring pulling motor mode. Motor
pointing to the right = right turns. Motor pointing to the left = left
turns. No CG conflicts on this configuration. Good protection to the
electronic stuff. Never broken it on bad landings, except 2 propellers
broken when my son Victor was piloting. It has been very reliable, because
in a medium windy day condition if a strong gust caught it high and away,
you can bring it down by angling the motor to pull down, until at a safer
altitude and distance, to get it back to you.h
Other examples of Rogallo Wing Experiments
Some suggestions for RCing the Simplwingy:
1) Try the "profane" mode, using a fin, with the motor in the back as a
puller, in front of the vertical rear axis, an actuator to the fin, also
located in the rear, under the motor, and the receiver and ESC located
more in the front, fixed. The lipo cell can be located more ahead of the
receiver/ESC group, on a movable cradle for the CG "tuning".
2) Using the motor in a vectoring pusher configuration (like an outboard
boat motor), with an actuator mounted ahead of the rear vertical axis
serving as the bending axis for the motor, and a movable cradle in the
front part with lipos, receiver and speed control, using tiny but reliably
flexible electric wires to connect the ESC to the motor and battery.
Agusto César Frazatto/ Brazil