Free Flight Sport
Gene Smith [email protected]
Doug Beardsworth's Diels Bf 109
In my September column I featured Doug Beardsworth's Spitfire. This column features his Diels Bf 109 Emil. It was constructed from the Dave Diels kit, which is based on Doug McHard's excellent plan in Flying Scale Models of WWII.
Doug wanted something slightly different, so he chose the desert camouflage scheme used by Jagdgeschwader 27 (JG 27) during the North African Campaign. The colors were sprayed using a plasticized nitrate-dope base, with Floquil model-railroad colors blended in. The finish added approximately 2 grams of weight to the Emil.
The kit decals were used for the crosses. The JG 27 Afrika decals were from a Techmod Decals set made for a 1/24-scale plastic model of a Bf 109 G. The fuel-marking triangles and fuel-filler caps from that set were also used. There are not many decals offered for 1/24-scale plastic kits, but those available can provide nice, authentic markings.
After flying the Bf 109 at the 2008 Flying Aces Club (FAC) Nats, Doug picked up several tips that helped his building and flying. One was to change the motor-peg location. The following winter he moved the motor peg forward by a full 2 inches. The same motor length was used but with more braided turns to prevent slack.
This resulted in two improvements: he was able to remove 2 grams of lead ballast from the nose, and he eliminated the fouling of the motor against the formers as it unwound in the narrow rear part of the fuselage. Those changes helped the Emil perform better.
If you plan to fly using a 15% motor (a rubber motor weighing no more than 15% of the model's empty weight is required in some FAC events), the peg can be moved forward to a point above the wing's trailing edge and still have plenty of hook-to-peg distance to manage that motor length. Doug found that two loops of 3/32 for a model of this size and weight will fit nicely into a 5- or 5½-inch hook-to-peg length.
With more radical repositioning of the peg, one should be able to remove another gram or so of nose weight.
With the gear down and dirty, this model will never be good for very long flights, but it flies pretty consistently for 30 to 35 seconds. It is set up with typical trim settings for a left-hand pattern — more washout in the right tip than the left, left rudder, and left- and down-thrust to suit the power.
Power has been two loops of 3/32 FAI Super Sport. The empty weight of Doug's Emil is now 26 grams. If you used chalked tissue instead of paint, built light aft of the CG, left off the landing gear, and used a forward motor peg, this kit could come in at the 20-gram range.
Propeller construction
The propeller is made from three blades of Peck-Polymers 6-inch propellers. The blades were thinned considerably by scraping them with a sharp, single-edged razor blade held vertical to the long axis of the propeller. They were separated at the center, leaving a 120° portion of the plastic bearing attached to each blade.
The blades were glued to a plywood backplate for the spinner. A brass tube with a ramp-type freewheel was used for the spinner bearing. Doug reinforced the joint of the three blades with small patches of 0.5-ounce fiberglass cloth and CA-glued the blades to the brass bearing and the plywood backplate. Doug believes the real magic for the durability of this propeller has been the thinning of the blades. He can fly it over relatively short grass without breaking the propeller.
Doug rates Dave Diels’ kit as superb, with lightweight wood and great 1940s-era decals. If Doug were to build the model again, he would make the changes noted. This model has good duration potential. He would love to do another one in early Battle of Britain colors and enter it in FAC World War II Combat.
The Diels Bf 109 kit is currently out of production, but Dave still sells the plans and may have some parts. He can sometimes be persuaded to make a run of a kit if there is enough interest. Contact Dave for information.
Other models and tips
This is the year for Bf 109s and MiG-15s. One of the photos shows Bill Schmidt’s version of Dave Livesay’s 1992 MiG-15 design. The model spans 20 inches, is covered with Polyspan Lite, and finished with nitrate dope. The rubber-powered model uses four strands of 1/8-inch braided rubber and an 8-inch propeller (the prop was removed for the picture). This design is a challenge to trim for flight, but it can fly well.
Howard Littman sent a useful tip for those who like small rubber-powered models. He has been using 1/4-inch plastic drapery-tieback rings for bearings on the motor-peg end of his motors for years. These rings provide all the benefits of a bobbin but are much simpler and easier to get the peg through when changing motors. Howard tried using them at the front end, but they climbed a conventional propeller hook.
They work with a Z-bend hook but it is bulky in a tight nose and is a trick to bend properly. The first one Howard bent from the instructions in the article looked beautiful, but was left-handed. (Been there, done that!)
One of the Blacksheep members, Matt Payne, turned his engineer’s eye to the problem and decided that the simplest solution was best. He bent an elongated hook that was the same width as the drapery ring. With the ring hooked into it, a simple universal joint is formed — and that’s it, almost. As the motor went slack, the ring would move forward and pop out of the hook. Matt solved that problem by braiding the motor to avoid slack.
Howard found another solution for those who don’t braid their motors or who like a “belt-and-suspenders” approach. He bent a detent into the hook, roughly a ring’s width from the back of the hook. The ring snaps into place when the motor is hooked and will not come out when the motor goes slack. Howard has flown two models with this setup and it seems trouble-free. This is what Howard will use from now on when he doesn't use a GizmoGeezer front end.
Karl Geis sent pictures of his Stringless Wonder built from a Peck-Polymers kit. It looks like a cross between a small kite and a flying wing. It is simple to build and flies well, so you might want to pick up a few kits for yourself and your grandkids.
The Peck line was purchased by A2Z Corp., which is now producing the kits with laser cutting and excellent wood. You can find most of your favorite Peck-Polymers kits at A2Z.
Many years ago Northrop sponsored a flying-wing contest. The Stringless Wonder won the event once or twice before being disqualified because it was “not really a flying wing.”
There is a new FAC event for half-size Wakefield models built and flown from 1937 through 1953. These models have roughly 50 square inches of wing area — slightly larger than an Embryo.
Dave Mitchell built his eye-catching Half-Wake from an Easy Built kit. For the initial test flights he used four strands of 1/8 x 25 inches to turn a Peck propeller. Dave’s model required a lot of negative stabilizer incidence (roughly 3/16 inch) and 1/32 inch of more positive wing incidence than shown on the plans.
With the wing in the forwardmost position, the model balanced at approximately 45% of the wing chord. The day of initial tests there was too much drift for full power, but the Half-Wake attained good altitude on limited winds. The glide was respectable but not great; that may have been because of drag from the decalage.
Dave discovered it was very important to have the stabilizer/rudder assembly keyed in position. Initially, the model flew erratically, often resulting in a steep right spiral dive under power. Dave keyed the stabilizer, which prevented the rudder from getting out of alignment. Rules for the Half-Wake event are on the FAC website.
If you live in the Dayton, Ohio, area, check out the McCook Field FAC Squadron. It is an active group that holds several contests each year, both at home and at the AMA flying site in Muncie, Indiana.
Take a look at Hobby Specialties. It specializes in hard-to-find items for the Scale, Sport, and Duration free-flight modeler, including inexpensive viscous DTs, quality balsa-strip wood, carved balsa propellers, and fine-spoked wheels. The items are produced by an aeromodeler for aeromodelers.
Bob Langelius Sr. has reintroduced several of the old Blue Ridge Models kits including the Square Eagle, a simple-to-build but great-flying P-30. The new kits are laser cut. Contact Bob at Pal Model Products for pricing.
MA
Sources
- Diels Engineering, Inc.
[email protected] www.dielsengineeringinc.com
- Flying Aces Club — Half-Size Wakefield
www.flyingacesclub.com/halfsizedwake.pdf
- McCook Field FAC Squadron
[email protected] www.mccookfieldfac.com
- Hobby Specialties
[email protected] www.hobbyspecialties.com/index.php
- Pal Model Products
32 Clinton St. White Plains, NY 10603 [email protected]
- A2Z Corp.
(877) 754-7465 www.a2zcorp.us
Transcribed from original scans by AI. Minor OCR errors may remain.
