The links below are from Google and are not necessarily endorsed by Art Wallace


Delta Vortex:



I recently completed the Delta Vortex by Bruce Tharpe. The plane comes in two forms.

The all balsa kit which can be ordered from:

Bruce Tharpe Engineering

8622 E. Evans Creek RD

Rogue River, OR 97537 USA

Information available at 541-582-1708

Orders 1-800-557-4470


Cost $119.95


There is a webring and a website on the plane at .


The plane is also available as a ARF from Cermark. You can look at it a . It

runs $269.95 and comes in two color schemes.


I built mine from the kit. It is not as complex as a traditional aircraft as you really only

build a wing.It took 40 or 50 hours to complete but I wasnít working all that hard on it. There is no cost savings building it yourself. The covering and glue came out to about $100 which makes my time worth exactly $1/hour. I greatly enjoyed putting it together and my kids got a good look at what is inside a plane so I have no regrets building it. If I destroy it rapidly, the next version will be the ARF. If it survives a while, I will build another from the kit.


What will I do next?I could see adding retracts, a dual axis gyro, and a separate elevator. The plans allow you to make it with elevons or ailerons and elevator.Since I have flown a lot of flying wings (Zagisand the Delta Bravo, I built it with elevons.I can see putting in both on the next version.


I modified the kit a bit.I donít like slime on my planes so I mounted the engine with the cylinder horizontal.Putting servos in the feul compartment did not make sense. Furthermore, putting a 12 ounce feul tank in a plane with a 0.91 engine was not on my agenda. I moved the throttle and rudder servos to the radio compartment and put a 32 ounce tank in the feul compartment.The plane balanced with 5 ounces shoved into the furthest aft area from the radio compartment. Lateral balance was good without any weight.


I have an O.S. 91 FX engine and a Futaba 8 UAFs 8 channel radio in it.The computer radio is very

nice because there is some programming to make it work well.The plane uses 6 servos.

One for each elevon, one for each of the two rudders, one for steering, one for throttle.

You can build it with separate ailerons and elevator and then it would require 7 servos.


Programming it took a bit of time.I used the Futaba 8U ComputerRadio Super book and the Getting the Most Out of Futabaís 8-Channel Radio Control Systems by Don Edberg. The Don Edberg book was a tremendous help in explaining what mixing was all about and actually making it work. The basic idea is this.


Channel 1: Left elevon.

Channel 2: Right elevon

Channel 3: Throttle ( I have the throttle cut set as well and it is great)

Channel 4: Right Rudder

Channel 5:

Channel 6: Left Rudder (Also Known As FLAP)

Channel 7: Nose Wheel Steering

PMIX-1: Rudder to Flap+ 100%†† +100% Link On Trim On Offset 0% SW-A Null

PMIX-2: Rudder to Channel 7+100% + 100% Link On Trim On Offset 0% SW-C Null

PMIX-3: Gear to Channel 7 +75% +75% Link Off Offset 0% SW-C Down

PMIX-4: Gear to Rudder -93% -75% Offset 0% SW-C Down

Airbrake Manu SW-C


With this set up the airbrake switch causes the rudders to shift in slowing the plane. If you put the gear up, then the rudders shift out as airbrakes.I will find out how different these effects are at altitude.


Flying the Delta Vortex:


Well, I have now put more than 100 flights on the Delta Vortex and it is a fantastic plane.I had a number of problems at first linked to the O.S. 91 engine.After I replaced the needle valve, needle valve assembly, and needle valve O rings, I corrected the air leak that was causing problems.The next problem was a loose screw in the head. The screw fell out, the cylinder started to leak, there was a lot of vibration and loss of power mid flight.It wrecked the head gasket. Once that was fixed every thing was better.The one thing I will say about the engine problems is simply that I had at least 10 dead stick landings from engine problems. I was able to put it on the runway every time without any damage:Fantastic plane.


Once, I got the engine adjusted, the weather turned lousy. Lousy weather in the Bay Area of San Francisco is very geographical.I live in Marin County and the weather is perfect in the summer. 80-85 degrees with wind in the afternoon and evening to cool things down. Over in Richmond where I fly it is cold (50-60 degrees) and very windy (15-25 mph) with gusts. The field is right off the bay and has lots of wind.I flew the Delta Vortex all summer long on a field with almost no other flyers. The weather was so bad that many weekends I was the only flyer on a Sunday morning.I flew on Saturday with white caps on the bay and no other flyers.Many people showed up, looked at the wind, and just left.The Delta Vortex hardly noticed the wind- Fantastic Plane.


So, now that I have more than 100 flights on the plane, most in high wind, I have some opinions.The plane handles wind well. It can do most acrobatic maneuvers. I have been practicing the Sportsman 2002-2004 pattern maneuvers with it.It flies them beautifully.


Takeoffs:Very easy. The large rudders make cross wind taxing in high wind a bit tough but it can be done. Cross wind take offs are not a big deal but dip the up wind wing tip a bit to keep it from being flipped over.Once you are in the air the plane flies perfectly.Spins are a bit flat. Hammer heads need a bit of power to keep air going across the rudders. Everything else is perfect. Inverted flight is easy with a touch of down elevator.Landings are lots of fun.Line it up, keep the throttle on in the wind, cut it when you are over the field. The plane has a tendency to make a flat stall when you loose airspeed. This problem can be a bit weird at first. The plane will be air born on landing. You will be about 3 or 4 feet from the ground and the wind must suddenly be less as you approach touch down. The plane will just pancake in.It looks bad but the plane survives fine.I cracked my muffler a month ago (I have it mounted underneath with a side mounted engine) but have done no other damage.


I have the airbrakes set up but they make the plane balloon when applied. I think a bit of down elevator mixed in will help it.


Taxing on the ground in high wind is a pain.It is hard to turn it around but it can be done. It then gets going a bit fast downwind on the ground, brakes might be nice.I have flown it in winds that were high enough that my car doors had to be held open to get the plane in. I have also flown it in wind where it was lifted off the ground and flipped over in the pits.The Delta Vortex is a wonderful plane that flies exceptionally, makes me look like a better pilot than I am, and can tolerate lousy weather and lousy landings. It is fantastic.



Excellent plane which flies wonderfully.




Art Wallace

The links below are from Google and are not necessarily endorsed by Art Wallace