The Flea

Don't want to play around with the big stuff? Check out this review of Diversity's new Speed 300 pylon racer. By Paul Bradley.

Flea

Specs:
  • Type: One Design Speed 300 Pylon Racer/Sport Flyer
  • Wingspan: 31 inches
  • Wing Area: 175 Sq. In.
  • Airfoil: e205
  • Length: 22.75 Inches
  • Recommended Power: Speed 300 turning a Graupner 4.75x2 prop on a 6 or 7 cell pack of 500 AR or AE cells.  Review plane 7x600AE cells.
  • Weight: 13 oz.  Review model weighed 12.7 oz. with 7 cell pack of 600AE cells.
  • Controls: Throttle, Aileron, Elevator.
  • Construction: Balsa with some lite-ply featuring laser cut parts
  • Manufacturer:Diversity Model Aircraft
    http://sefsd.org/diversity-model-aircraft/

 

Introduction

Not too long ago I wondered out loud to the EFLIGHT list why we don’t see more applications for the Speed 300. I had been flying a model powered with the Speed 300 and felt that it was a very nice complement to the ‘400' class of models that so many of us like to fly. I didn’t know it at the time, but our friends at Diversity Model Aircraft - the people who bring us the Skat - had recently developed a great Speed 300 model called the Flea. I was very pleasantly surprised to learn about the Flea, and was of course anxious to try one on for size. The Flea is stated to be a one design Speed 300 pylon racer, or sport aerobatic model. It is the latter category that was most appealing to me. The Flea’s light weight and relatively large wing area seemed ideal for a small-field punch-some-holes-in-the-sky type of model. I WAS NOT DISSAPOINTED. Before we talk about flying, though, lets look at the kit and its construction.

 

Kit Contents

Flea kit contents
Figure 1. Kit Contents

I don’t know about you, but I really love to open up a kit box to see what is inside. The smells that come out of the box when the lid is removed and the initial curiosity of what I will find inside are always lots of fun. The Flea kit was no exception. The Flea uses conventional balsa construction, so there was a nice assortment of wood to examine. Although traditional in construction material, the Flea also uses laser cut parts. So upon removal of the sheets from the box, you are immediately struck by the very cleanly cut parts lurking in the sheets. There are also some parts cut from lite ply, and they are equally sharp and clean. Included in the lite ply laser cut parts is the motor mount, control horns, wing bolt plate, and some key fuselage bulkheads. The full size blue print plan is well laid out and includes all of the templates for each part used in the model. The kit also includes a vacuum formed canopy and a set of decals. The decals are a nice set of laser printed graphics on a clear self adhesive sheet. A hardware bag is also included that provides the materials necessary for all control linkages and wing mounting. Completing the kit contents is an assembly step check off sheet. The only items that you may have to acquire other than covering material and adhesives are as follows:

  • A .040" drill that is used in making the aileron control horns.
  • An 8-32 tap for the wing bolt plate, or an 8-32 blind nut.

Before proceeding with the actual construction of the Flea, I would like to comment on the wood provided in the kit. As a long term scratch builder, this is always an area of special interest to me. It seems that far too often, we are forced to replace portions of the wood included in kits. I am happy to say this was not the case with the Flea. All of the wood in the review kit was well selected. It represented a very good balance between strength and light weight. To be more specific, I weighed the individual sheets and found them to be in the following density range:

  • Fuselage sides - 15 lb
  • Wing ribs - 8.5 lb
  • Rudder/Fin - 6.7 lb
  • Stab/Elevator - 7.5 lb
  • Sheet Stock - 6.7 lb

The fuselage sides represent a relatively small volume in the completed airframe, so the heavier wood does not represent a weight penalty, but does provide very good strength where it is needed. Again a nice balance between weight and strength.

 

Construction

Wing

After studying the assembly step check off sheet and plan, I began the Flea’s construction with the wing. This is very straight forward. The design uses a conventional shear web spar and rib layout in the wing structure. What is nice with this kit is the way the wing construction is developed, which is really enhanced by the precision of the laser cut parts. The entire wing construction is keyed to the spar. It is much like laying courses of bricks. You begin by laying down the bottom spar cap. The review kit used balsa spar caps. Current kits are using spruce caps. The center laser cut plywood shear web, with its neat lightening holes, is then added. From there it is a simple matter of adding a laser cut shear web and rib one bay at a time. The precision of the laser cut shear webs insure they will fit properly between the spar caps.   In no time you have all the ribs and shear webs in place and are ready to add the top spar cap. The review model ribs included two laser holes to allow trapped air to escape from each rib bay. Current kits have replaced the air bleed holes with lightening holes.

Flea wing spar is the key to wing construction
Figure 2. Wing Spar is the construction key

Once the spar and rib assembly is complete, you notch the trailing edge stock to receive the ribs. The leading and trailing edges are then added. The leading edge of the review kit was glued flat to vertical faces on the ribs. A modification has been made to current kits where the ribs have a 45 degree notch. This should make assembly a bit easier, and will reduce the amount of necessary leading edge shaping.Wow, the wing is almost done already.

Flea wing with LE and TE added
Figure 3.  Leading and Trailing Edges are added

The tips are added next. A kit revision has been made where the tip pieces now include lightening holes. The tip design uses ribs to form the final tip shape. Due to the variations that will occur during the construction of individual models, the tip ribs are not included in the laser cut parts. They are made from available 1/6" stock and sanded to shape in place. At this point you sand the leading edge to shape and make sure everything is smooth and clean.

 Tips are added and tip ribs are shaped
Figure 4.  Tips are added and tip ribs shaped

The ailerons are then cut away from the trailing edge.

Ailerons are cut from the TE
Figure 5.  Ailerons are cut from the trailing edge stock

The wing is completed by preparing the aileron horns. This is done using the provided materials. The basic horns are bent and cut from piano wire. A brass tubing horn pivot is added to the piano wire horn before the bends are completed. Brass tubing is then used to form the horn ends that will receive the control links. The brass horn ends are secured to the piano wire with solder. When the horn assemblies are completed, they are glued to the wing assembly. The ailerons are then fitted. That completes the wing assembly and makes it ready for covering.

Aileron horns are fabricated and added
Figure 6.  Aileron horns are fabricated and installed

Fuselage

Building the fuselage follows traditional steps. Triangular stock is glued to the nose section of each fuselage side. This makes it possible to shape the nose later to a nice round section. The rear of the fuselage sides receive 1/8" square stock. The 1/8" laser cut lite ply bulkheads are glued to one fuselage side. The second side is then added. Once both sides are in place, the rear of the fuselage is glued together.

Basic fuselage structure
Figure 7. Basic fuselage structure

A neat feature of the fuselage structure is the way the rear portion forms a nice elevator push rod guide and exit. This is done by the previously added 1/8" stock There are a number of design features of the Flea that contribute to a clean and efficient structure.

Push rod exit formed by rear fuselage structure
Figure 8. Push rod exit formed by rear fuselage structure

Once the rear of the fuselage is closed, the laser cut lite ply motor mount is added to the nose. At this point the elevator servo is fitted. Once the mounting rails are in place the servo is removed. The turtle deck stringers are added along with the top and bottom sheeting. The plans call for an opening to be left in the bottom of the fuselage under the elevator servo location. The opening is then to be covered after the elevator servo is installed. I chose to make a removable hatch for the elevator servo opening.

The only problems I had during the construction of the fuselage were with the turtle deck support bulkheads and the wing bolt plate. Although the laser cut turtle deck parts conformed to the plan drawing, I could not make them fit. The solution was a simple rework of the supplied parts. Contact with Diversity Model Aricraft confirmed that this problem has been corrected in current kits. Diversity Model Aircraft also mentioned that a future kit modification will be to include tabs on all bulkheads with corresponding slots in the fuelsage sides.

After installing the lite ply wing bolt plate, I found that it would flex excessively when the wing bolt was tightened. During the normal installation and removal of the wing from the fuselage while building the Flea, the lite ply wing bolt plate failed. As a result I replaced the provided lite ply wing bolt plate with one made from regular 1/8" ply. The finished fuselage is a very light and strong assembly.

Completed fuselage structure
Figure 9.  Completed fuselage and shaped nose

Final Assembly

Once the wing and fuselage are built, the model is effectively complete. The tail feathers are sanded smooth and prepared for hinging the elevator. The review model tail surfaces are solid sheet balsa. Current kits have lightening holes cut in the tail surfaces. Once the tail surfaces have been prepared everything is covered. I used Sig Supercoat Cub Yellow  to cover the review model. This is a nice low temperature film that is fairly light.

As noted earlier, the supplied decals are laser printed graphics on a clear self adhesive sheet. Since the decals were created by a laser printer, I decided to have a little fun. There is a product called Color Foil that is intended to dress up laser printed material. It comes in many colors and patterns. It can be found at office supply stores, and some computer stotres. I had decided to trim the basic yellow color of the review Flea with blue. As a result, I chose some metallic blue Color Foil to add a little color to the decals. The process involves placing a piece of Color Foil over the laser printed material, and then feeding the combination through the printer again without printing the image a second time. The heat of the laser fuser causes the foil to transfer to the laser applied toner of the underlying graphic. It produces a very nice result. Due to the trim scheme I chose for the Flea, I ended up only using the decal with the model’s name on the fin.

Decal sheet and ColorFoil        Flea16.jpg (4822 bytes)
Figure 10.  The laser printed decals and some ColorFoil

After covering the model, the equipment was added. While the Flea is compact, I was pleasantly surprised to find that installing the equipment in the model was easier than expected. I chose the Castle Creations Sprite 20 as the speed control because of its small size and light weight.  The motor and ESC were then "dropped" through the wing opening and fed forward to the motor mount. It was easy to align the motor mounting holes with those in the laser cut motor mount.

Motor and ESC layout
Figure 11.  Motor and ESC layout

The elevator servo, an FMA S80, was then installed in the fuselage. This was done using the opening that had been left in the fuselage bottom. The stab/elevator was then glued in place. Now it was possible to set up the elevator push rod. When all was in place, the bottom of the fuselage was closed up using the hatch that had been previously prepared and covered. The hatch was secured using rubber cement. A coat of rubber cement was applied to the fuselage and to the hatch edges. It was allowed to dry and then the hatch was pressed into place. This makes a secure hatch, that can also be reopened if necessary with out having to cut away fuselage covering.

Elevator Servo Access Hatch
Figure 12.  Elevator Servo Access Hatch

With the fuselage assembly complete, the aileron servo was added to the wing. This was an FMA S90. The control links are made up from .040 piano wire. Adjustments to the length of each control link is made by adding a "V" to each link. This makes it possible to make fine length adjustments. It was not difficult to set up each aileron link and make the needed adjustments.

Aileron servo setup
Figure 13.  Aileron servo setup

The final step in completing the Flea was installation of the radio. The battery pack rests on the fuselage bottom under the wing. This leaves space above the battery pack for the receiver and the aileron servo when the wing is in place. I initially used a Futuba 4 channel AM radio. This was small, light, and fit very nicely. I later used an 8 channel FMA 2000 receiver. The reason for the switch can be found in the flying remarks. The 8 channel FMA 2000 is not the smallest receiver available, but it did fit between the fuselage sides and between the battery pack and wing. The receiver antenna was routed through the fuselage and out of the elevator push rod exit.

Receiver Installation
Figure 14.  Receiver Installation

The wing bolt hides underneath the vacuum formed canopy. To make it easy to install and remove the wing bolt, I made a simple tool from some brass tubing.

Wing bolt tool
Figure 15.  Wing bolt tool

The plans indicate the Flea’s flying weight should be 13 oz. The instructions also indicate that either a 6 or 7 cell battery pack can be used. The review model came in at 12.7 oz using a 7 cell battery pack of 600AE cells and the FMA 2000 receiver. This was very acceptable. The Flea kit builds into a very attractive model that looks like it really wants to fly.

Finished Flea
Figure 16. Finished Plane

 

Flying

After completing the Flea, I could hardly wait for the first flights. When flying day finally arrived, I got to the field early. There was no one else present except my brother who also would serve as the launcher. I wanted the first flights to be launched by some one else so I could be on the sticks right from the beginning. With every thing checked on the ground, and after getting a good range check, I called for the launch. The Flea leaped into the air. I throttled back to get a feel for this sprightly model. After two overhead circuits I lost all control of the model. No response from any radio input. The Flea went into a tight spiral dive from about 50' up and hit the dirt straight on. I feared the worst. Upon arrival at the crash site, rather than a smoking hole I found a fairly intact model. The motor had punched through the lite ply motor mount, the battery pack had taken out the fuselage bulkhead that also served as the forward wing mount, and the wing leading edge was pushed in a bit. That was it! The wood selection for the kit proved itself in spades in terms of strength and overall light weight. A few hours later, the model looked no worse for wear.

Ready for the first flight
Figure 17. Ready for the first flight.

Round two was a week later. This is where I decided to switch from the Futuba AM receiver to the FMA 2000 FM receiver. Ground range checks again indicated everything was fine. So I called for the launch. With no effort at all, the Flea headed skyward. I was concerned about the current draw of the Speed 300 on 7 cells so I pulled the throttle back a bit almost immediately after launch. The Flea just kept its noes up and headed for the clouds. The model was in trim right from the beginning. I was struck by how easily it responded to the controls without being overly sensitive. After a few left and right circuits, I decided to ring her out a bit. Loops are large and very easy to make smooth. The Flea is really very smooth in spite of its pylon racer heritage. She rolls very nicely and is a snap to fly inverted. Quite frankly, I was amazed at how easy the model was to fly. I had expected it to be very sensitive and a bit of a hand full. What I found was a very agile model that was well behaved. You have to stay with the Flea, and it moves along at a brisk pace, but it is a very nice model to fly. The light weight of the Flea along with its 175 in2 wing area makes a real winner of a model that is a blast to fly. After several flights I think I’m hooked on this bird.

I’m not yet a pylon racer, so I can’t really comment on how well the Flea handles this role. I can only assume that the way it turns and tracks through maneuvers, that in the hands of an experienced pylon flyer the Flea would really groove around the course. As a wrap up, I would like to quote from the Diversity Model Aircraft Flea building sheet, "Show up at your flying field with this speedy little racer, and watch as everyone looks on in amazement". Very true words. The Flea is a real keeper.

 

Recommendation

This is a complete kit and very good value at $49.95. About the only thing I would change is the lite ply wing bolt plate. As is always the case with different modelers building the same model, some would probably change the building sequence. You really can't go wrong following the suggested building sequence, but if I were to build another Flea, I would set up the ailerons while the bottom of the fuselage is still open. That would provide better visibility of the control horns and any interference with the wing bolt plate. The printed building sequence calls for the ailerons to be set up after the bottom of the fuselage is planked.

One other suggestion would be to use a 6 cell battery pack. The Speed 300 can pull some real current on that little 5x2 prop and a freshly charged battery pack. I had to be very careful with the throttle position while using a 7 cell pack so I would not let smoke out of the motor. On the surface that does not seem like a hard thing to do. Once airborne, the Flea can easily seduce your throttle thumb to go for broke.

The Flea is a definite winner. I highly recommend it to anyone who would like to try a Speed 300 powered model and has a little flying experience. This is one model that will travel with me when ever I plan to visit the local flying site. It is just too much fun to leave at home.

Liked:
  • High quality and precision of the parts.
  • Balsa selection.
  • Structural design.
  • Complete hardware.
  • Excellent flying characteristics.
Didn't Like:
  • Lite ply wing bolt plate

If you have any question feel free to contact me BradleyP(at)ix.netcom.com

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