The Autogyro Company of Arizona, in cooperation with Clancy Aviation, has developed an autogyro conversion kit to be used with the standard Lazy Bee airframe and empenage. The Autogyro Company of Arizona considers the Gyro Bee to be their autogyro "trainer", due to its gentle flight characteristics. The Gyro Bee conversion module is designed so the final fore/aft balance (hang angle adjustment) doesn't change any of the balance or control throw settings from an already flown Lazy Bee. This design feature allows the pilot to take both the Gyro Bee conversion module and his "winged" Lazy Bee to the field for a quick change and fly combination. (Fixed wing and autogyro model all in one.) Fly it as a Lazy Bee one flight, take the wing off, new gear in (although a lot of their customers report they prefer the Gyro Bee landing gear instead of the stock gear for both), drop on the conversion module and fly next as an autogyro. The Gyro Bee autogyro conversion kit contains all the parts required to build the mast and rotor assemblies. A combo kit is available from Autogyro Company of Arizona and consists of the Gyro Bee conversion kit and a Lazy Bee kit from Clancy Aviation. For this review I built a Lazy Bee fuselage and empenage from scratch using plans I procured years ago from Clancy Aviation. This allowed me to control the balsa density and apply some design modifications I have developed over my years of flying Lazy Bees. Detailed Lazy Bee fuselage construction will be featured in a review I plan to publish sometime in the future.
After flying this ship I can attest to its ease of airborne flight. Having said this, the reader needs to be aware that autorotation flight varies very little from fixed wing flight with the distinct exception of take-off and landing. The specific requirements of take-off and landing will be covered further in this article. I found that autorotation flight was very alluring and I am eager to further develop my skills in this area. After spending a morning with Steve Tillson, founder and owner of the Autogyro Company of Arizona http://www.autogyro-rc.com, I learned the minimum theory and practical skills to effectively practice autorotational RC flight. The information gleaned in this session will be sprinkled throughout this article and is contained in the Gyro Bee video available from Autogyro Company of Arizona. Steve not only sells kits but he promotes the autogyro industry. He provides excellent customer service through phone, e-mail, and personal visits. He spends a lot of time traveling and meeting new autorotation pilots and is a pleasure to work with. I can not imagine a better source of autorotation expertise, information, and assistance. When you buy a kit from Steve you also get his support. If fixed wing flight is getting a little old and you are looking for something a little more offbeat/interesting, I would suggest you entertain autorotation flight for your next conquest. I do not recommend this approach to someone that does not have fixed wing RC experience. Although autorotation is not super hard, the autogyro needs to be kept close for visual orientation and requires the familiarity of stick handling that only comes with practice.
The construction manual addresses the use electric power with the Gyro Bee. The recommended static thrust is 2.25-2.5lb. Static thrust measurements of my Astroflight 05G with a Master Airscrew (MA)11X7 wood prop and a MA 12X8 folding prop would not produce an average of 2 lb. thrust throughout the discharge of the batteries. Through static testing I was able to determine that an Astroflight 05 motor geared with the Astroflight super gearbox (3.69:1) swinging a MA13x8 wood prop on 10 cells would provide adequate thrust (3 lb. initially, settling down to 2.5 lb.). For further information on motor/gear/prop combinations you can visit Astroflights website http://www.astroflight.com/superbox.htm . The same set-up using 7 cells appeared to produce marginal thrust (2.25 lb. settling to 1.75 lb.).
Electric Conversion Recommendations
- Follow the electrification instructions provided with the Lazy Bee instructions and consider additional lightening in accordance with the fuselage pictures below.
- Use a geared motor that produces at least 2.5 lb. of static thrust. For propeller selection the overall airspeed is about the same as the electrified Lazy Bee fixed wing plane ~ 15 mph to 45 mph.
- It appears that a minimal cell count of 10 cells will be required to achieve the thrust goals. The additional weight of large capacity cells did not effect the Gyro Bees performance.
- As always with an electric conversion, use smaller/sub micro servos and receivers. Make sure that you use metal geared servos for the rudder and rotor tilt functions.
- Make sure that the Lazy Bee axle box is reinforced per the Gyro Bee instruction and add additional braces fore and aft where the axle box intersects the fuselage sides.
- Use ¼" balsa gusset to support all the structural frame joints going across the fuselage top. These are the beams that the Gyro Bee mast rides and aligns on, so it may also be wise to use hardwood frames instead of balsa. The battery adds additional moments to the frame structure and the corners are the first place glue joints break. I also recommend using epoxy on these gussets to increase their resistance to moments incurred.
- Dont scrimp on the battery mount floor. If it is too light it will fracture or distort, breaking the glue joints.
- Reinforce the fuel tank shelf with thin ply and mount the ESC under the fuel tank shelf with Velcro. The cooling air hole in the chin of the fuselage provides adequate cooling to the ESC and battery (see picture below).
- Hollow out the firewall and the fore section of the fuel tank shelf to make room for the wires to the motor and to reduce weight.
- With the additional weight of the mast and rotor assembly (46 oz.) I would recommend replacing the forward most vertical frame members with 1/8 X 1/8" hardwood instead of the balsa. In the instance of a hard vertical landing these frame members would better transfer the load to the landing gear without buckling. You also have to consider battery shift when this happens (a major source of frame damage). All in all I think this set-up would increase the Gyro Bees survivability.
- Although I did not take advantage of it, there appears to be additional lightening possibilities in the rotor mast assembly (lightening holes).
At first glance the kit appears deceptively simple to build. In reality none of the construction steps are groundbreaking or difficult to perform. The construction manual is exceedingly detailed and is accompanied by many good photographs, but it requires multiple readings to comprehend all the enclosed information. All material and tools required are identified at the beginning of each section. The construction manual also covers balancing and flight instruction. The materials supplied are superb and packaged very well. I did notice a significant difference in rotor balsa density. While talking with Steve Tillson he explained the rotor balancing process but did admit that he did not have the resources to ensure perfect balsa density matching. The laser printed plan sheet is excellent and divided into subsections called plansters. These sections are to be cut out and used to build over on small workbenches. This is a neat concept but I have mastered working with plans that are larger than my workbench and I did not cut these sections out. The Autogyro conversion kit I received was complete and included the components listed below:
1 laser cut sheet of 1/4" ply 4 pcs. #2 X ½" Sheet metal screws 3 Laser cut and milled balsa rotor blades 2 pcs. #2-56 X 10" threaded rods 1 Laser cut sheet of 1/32" ply 2 pcs. #2-56 Tufsteel Clevises 1 Laser cut sheet of 1/8" balsa 2 pcs. #6 X ¾" Socket head sheet metal screws 1 pc. ½" x ½" x 36" Triangular cut balsa 4 pcs. #64 Robber Bands 3 pcs. 3/32" x 36" Bright music wire 1 pc. Laser cut flex hinge (rotor head/flex plate) 1 pc. 1/8" OD brass tube. 1 pc. Rotor spacer 2 pcs. 1/8" Pre bent music wire landing gear 1 pc. MA gear box with prop adapter 2 pcs. 1/8" Wheel collars w/set screw 1 bag Lead shot + cotton ball (tip weights) 3 pcs. #6-32 Aircraft lock nuts 1 sheet (36"x48") Rolled-laser-plotted plan 3 pcs. #6-32 X ¾" Socket head cap screws 1 pc. #4 x 32 Socket head sheet metal screw 3 pcs. #6 Flat metal washers 3 pcs. #4 flat washers 2 pcs. Nylon control horns
The Gyro Bee autogyro conversion kit contains all the parts required to build the mast and rotor assemblies. All construction operations are pretty standard and straight forward. If someone has the skills necessary to built the Lazy Bee fuselage and empenage they should have no problem with the autogyro conversion kit. The only aspect of construction that challenged me was the final rotor balancing and flight path verification operations.
The rotors consist of pre-shaped balsa rotors with music wire glued to the leading edges. The only significant aspects to their construction are the sanding of the trailing edge and span wise balancing. Both of these operations are explained in great detail in the construction manual. The photo below is a rotor tip covered with transparent covering and the balancing channel filled with cotton.
The mast profile construction consists of a balsa core sandwiched between outer plywood sheets. If I were to do it again I would lighten this assembly. Out of the 60 oz. weight of the complete model, the rotor and mast assembly weighed 13 oz. The photo below shows the balsa core with the brass tube sleeves that comprise the rotor yaw control feature.
Landing Gear Modifications:
The Gyro Bee comes with pre-bent landing gear that is much taller and wider than the standard Lazy Bee gear. To support the additional loads on the Laze Bee landing gear box, additional reinforcement sheeting is added to both sides of the axle box. In my opinion the Lazy bee axle box design has always been too weak, and I would suggest the addition of corner braces between the axle box and the forward and aft airframe sections. The photo below shows the modifications made to the standard lazy Bee axle box.
In order to make the Gyro Bee an emergency hands off trainer, the design has incorporated a built in "hang angle" that ensures the Gyro Bee will autorotate without any input from the pilot. Proper hang angle is achieved through location of the rotor bearing on its mounting plate. The electrified Gyro Bee had a perfect hang angle with the bearing assembly mounted in the aft most screw holes. The photo below is scanned from the construction manual and shows actual measurement of the hang angle.
I found rotor balancing difficult and tedious. The construction manual is quite frank and forthright about the frustration of this process. I finally ended up placing the rotor blades 120 degrees to each other (using a builder square and the flat surfaces of the flex plate) and balancing the assembly at this fixed position. Steve Tillson discouraged this practice because the blades do not always fly 120 degrees to each other but I got good results from this method and could re-verify the location of the rotor blades before I buttoned up the rotor tips. My rotors were not perfectly balanced but the addition or deletion of one led shot negatively effected the total system. This is where I stopped and the system worked fine. I also made sure that the rotors are not warped when I covered then with Monokote. I highly recommend covering the blade tips in contrasting colors. Have a partner get the blades into autorotation and walk alongside and observe the rotor blur at the edge of the disk. If it appears to be greater than ¼" shim the highest and lowest rotors with tape between the underside of the rotor and the flex plate until rotors fly on roughly the same plane. The care I took in covering paid off because all blades tracked on roughly the same plane and shimming was not required.
Note: When adding and removing lead shot just put a piece of tape over the opening to the channel in the blade tip. Wait until the system is balanced as well as you can get it before stuffing cotton into the end of the channel. This will save you a lot of time and frustration. Also do not expect to achieve PERFECT balance, but you should be able to get close.
To get the blades into autorotation I tried everything including climbing on the roof and holding the assembly over the air conditioning condenser fan. In practice the blades should be loosened (just enough to let them move on the flex plate with very little force) and allowed to "catch the wind" to begin the autorotation. It does not take much walking speed to get the blades into autorotation, but if they have not "caught the wind" you can walk all you want and you will not get them to speed. There is a distinct "swooshing" sound the rotors make when the blades "catch the wind". To date the best way I have found to accomplish this is to spin the rotor assembly and hold it almost perpendicular to the oncoming air. Once I begin to hear the "swooshing" sound I start walking into the wind and tilt the rotor assembly to about a 45 degree angle of attack to achieve full rotation. The photos below show my static balancing blade location technique and an attempt to capture the rotor flight path verification. Unfortunately the shutter stop was too quick and you do not see the tip blur as witnessed by the observer.
Align the scale from a builders scale with the trailing edge of the rotor. Make a line down the length of the scale. Remove the scale, insert into 90 degree handle, and align with the opposing edge of the flex plate. Move the rotor until the scale and the lines are parallel.
As I stated before, the airborne flight of the Gyro Bee is easy for the experienced pilot but visual orientation is much more difficult. For this reason the Gyro Bee needs to be kept "close in" until the pilot has sharpened his recognition and autorotation skills. Autorotation varies the most from fixed wing flight in landing and take off processes. I have not graduated from hand launch so this is the only take off information I will provide.
The Gyro Bee flies with traditional rudder and aileron yaw controls. Altitude is achieved through the application of throttle and forward momentum is controlled by elevator/rotor angle of attack. To slow the Gyro Bee down give the model up elevator and to speed it up give the model down elevator. The rotor will not stall but there is a condition called "falling off the beach ball" primarily associated with steep angle clockwise turns. Steve Tillson goes into great depth explaining this phenomena. To avoid this keep the bank angles relatively flat and only fly counterclockwise until you have a good feel for autorotation flight and disaster recovery. In case of emergency the Gyro Bee is designed to autorotate to the ground without pilot intervention. In cases of disorientation it is advisable to let go of the sticks, allow the model stabilize, and figure out where it is going. For me, autorotation is an interesting diversion from fixed wing flight and really neat! The landings are impressive and the sound of the rotors beating the wind is most impressive. I can imagine a lot of neat maneuvers but I am not at the point where I feel comfortable executing them.
The Gyro Bee needs to be in full autorotation before it will fly. This means that the rotors need to be spun up to full speed before they will provide the stable and predictable lift required for take off. The blades should be loosened (just enough to let them move on the flex plate with very little force) and allowed to "catch the wind" to begin the autorotation. There is a distinct "swooshing" sound the rotors make when the blades "catch the wind". To date the best way I have found to accomplish this is to spin the rotor assembly and hold it almost perpendicular to the oncoming air. Once I begin to hear the "swooshing" sound I start walking into the wind and tilt the rotor assembly to about a 45 degree angle of attack to achieve full rotation. Once the "swooshing" sound intensifies you increase the forward momentum, give it full throttle, and throw the Gyro Bee forward perpendicular to the ground. The Gyro Bee will immediately begin to lift and it will give you plenty of time to get your thumbs in the sticks. Always try to fly the Gyro Bee counterclockwise until you feel you have mastered autorotational flight.
Gyro Bee landings can be achieved at more than a 60 degree angle of approach. It is recommended that beginners make approaches of 45 degrees or less. It is sufficient to say the approaches are a lot steeper than in fixed wing aircraft. It is also very important to land straight into the wind. Right before touch down a large flare with a full throttle will stop forward momentum and gently sets the Gyro Bee on the ground. This is when things get tricky. If the landing gear is not drastically spread out the Gyro Bee will still be in autorotation (flying). The rotor is still spinning and needs to be watched/flown to ensure the model stays pointed into the wind and does not get blown over by a side gust. The pilot needs to manually slow the rotor until autorotation ceases. The flight is not over until the rotors come out of autorotation!! The best method of dealing with this condition is to bend the landing gear so the rotor angle comes as close as possible to parallel with the ground. The pictures in this review DO NOT depict the landing gear bent to an optimal parallel position. The Gyro Bee in the pictures would fly on and on and was a problem in the hands of an inexperienced autorotation pilot. I later bent the landing gear so that Gyro Bee was as close to the ground as possible without the possibility of a prop strike. In this configuration, after landing, the rotor came out of autorotation by itself. The construction manual suggest lowering the landing gear somewhat but I am advising to make it as low as possible.
The Gyro Bee is a lot of fun. It is easy to build but a little more difficult to balance. With electrification, disk loading is increased, but this does not seem to effect the Gyro Bee's flight characteristics. The electrified Gyro Bee in the attached photographs flew just as well as its wet fuel counterpart. I have had a lot of fun flying the Gyro Bee but I must admit it is learning over for me. My fixed wing experience has given me mastery of the sticks and airborne flight but tracking the Gyro Bee has been a bit more difficult. Orientation can be lost easily! I assume, and recommend, a fuselage with contrasting colors on each side. This would be much easier to track but may look a little unconventional. Landings are a lot more vertical and I have learned that the show is not over until the rotor comes out of autorotation. No more automatic sighs of relief when the wheels hit the ground. All in all I would recommend the Gyro Bee to an experienced pilot looking for a more unique diversion than electric fixed wing flight. A note of warning: it could become obsessive and you just may find yourself leaving your fixed wings at home.
Jim Dall dallphin(at)dakotacom.net
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