RC Micro World Online Magazine - December 2005     by permission.

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 control)..
- 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

John Worth