I just finished building a second prototype of the electric V-Bat with a smaller duct and larger wing. Here is a video showing it hovering indoors in a confined area. It has a 6 ft span and weighs 12 lbs as flown in the video.

Steve

eV-Bat Hovering Indoors (0 min 52 sec)

Originally Posted by mlbco

I just finished building a second prototype of the electric V-Bat with a smaller duct and larger wing. Here is a video showing it hovering indoors in a confined area. It has a 6 ft span and weighs 12 lbs as flown in the video.

Steve

http://www.youtube.com/watch?v=d3myqHdEwjA

nice work,Steve
The new duct is shorter ,why do you make this adjustment， the weight or the drag?

Very much impressed again,thanks for sharing
you must have spent a lot of efforts for the job
regards
Sam

That is pretty awesome Steve. Good job.

Kasra

Steve,

I have a question for you: how much static thrust increase of your V-bat compared to open propeller same size? Why you decide to use symmetrical shape instead of optimized shape? how many channel radio you use?

Originally Posted by zebra100

Steve,

I have a question for you: how much static thrust increase of your V-bat compared to open propeller same size? Why you decide to use symmetrical shape instead of optimized shape? how many channel radio you use?

We are using a cut-down propeller in the duct so I don't have a direct comparison of the propulsion system for the propeller with versus without a duct. A well designed duct produces a given amount of thrust for less power than an exposed propeller and in our case the figure of merit (FOM) in hover is close to 90%. The FOM is the ratio of ideal power to the actual power, where the ideal power is defined as the minimum induced power required to produce a specified thrust in hover. 90% FOM is higher than most exposed rotor systems (typically 75%).

The duct cross section is not symmetrical, it is designed for both efficient hover and low drag in high speed flight. I tried to keep the duct as small as possible to minimize weight and drag, while still providing the function of a ducted fan and the aircraft's tail.

The radio is 4 channels set up like a helicopter's controls. There is an on-board computer with GPS, magnetometer, gyros, altimeter, airspeed, and accelerometers that provides attitude stability when hovering. Eventually, this computer will fly the V-Bat autonomously with no human control input. The duct has 8 servos and the ailerons have 2 servos, but there are only 4 controls (roll, pitch, yaw, throttle).

Steve

Can it fly autonomously in the transition between vertical and horizontal flight?
Kevin

Originally Posted by zhaohongf22

Can it fly autonomously in the transition between vertical and horizontal flight?
Kevin

The larger version can hover autonomously and both versions have been transitioned under manual control. We are finishing up the flight control for full autonomous flight now.

Steve

Will the transition be achieved by a stall-and-tumble maneuver or continuous ascent transition?

Kevin

Thank you very much for the quick reply, Steve. I'm very impressed with the V-bat. How can you cut the blue foam curve so smooth for the shroud?

Why the need for 8 control vanes? and the boxes round each one?

Thanks, Terry

The type of autonomous transition will depend on the amount of excess thrust available. UAVs typically operate with maximum fuel and payload and don't have anywhere near as much excess thrust as model airplanes. With less thrust available the transition will probably be a smooth ascent or descent.


The blue foam duct was cut using a custom set of cutting bits mounted in a milling machine. The foam was rotated on a special table while the mill cut the foam duct. The duct was cut in several stages using the appropriate bit.

The vanes in the duct and the extra attachments are needed to provide adequate control authority in the roll axis (i.e. axis along the fuselage). When there is wind the wings tend to roll the V-Bat so that the wing surface is perpendicular to the wind. Significant vane authority is required to minimize this in high winds.

Steve

Here are some photos of the duct construction showing the hollowed out foam duct and the underlying structure.

Steve

Originally Posted by mlbco

The vanes in the duct and the extra attachments are needed to provide adequate control authority in the roll axis (i.e. axis along the fuselage). When there is wind the wings tend to roll the V-Bat so that the wing surface is perpendicular to the wind. Significant vane authority is required to minimize this in high winds.

Steve

Hi Steve,

Do you have a roll mix input in each of the 8 vanes ?

Or would you explain ( just a bit, I don't want the code's formula ) the % mixing used in the 8 vanes, yaw, pitch, roll ?

Lebrett,

All the vanes move the same direction for roll control. For pitch and yaw it's just like rudder and elevator on an airplane except that the vanes at the 45 deg radial stations only move 0.707 as much as the primary vanes.

Steve