RADIO CONTROL SOARING
Mike Garton, 2733 NE 95th Ave., Ankeny IA 50021; E-mail: [email protected]
THIS MONTH I have three topics to cover. First is the debut of the Phoenix glider from CHK Modelle (Germany). Second is information about the Torrey Pines Gulls Hand-Launched Glider (HLG) timing CD, which will be useful if you are going to run a local HLG contest. Third, I'll give an update on the F3J "anchor rule" passed by the Fédération Aéronautique Internationale (FAI).
The Phoenix is a newly imported molded glider designed for F3B. "Phoenix" is the English version of the German name. The logo on the airplane is spelled "Phonix" with two little dots (umlauts) above the "o." Umlauts are used in the German language to denote a different pronunciation for some vowels. In this case, an umlauted "o" means that it is pronounced more like an "e." When I see the logo, it reminds me of the Hooked on Phonics TV commercials.
CHK in Regensburg, Germany makes the Phoenix. The company started producing molded airplanes in 1976. This means that it had been in business for 13 years when the iron curtain fell.
Jan Stanek (JASA models) was the chief builder of the Phoenix. At least two other European molded-airplane manufacturers also use his work. The JASA connection complicates the lineage of some models, such as the Sharon or Space gliders. CHK and its rival HKM make versions of each.
The Phoenix uses the HQ2/8.0 and HQ2/8.5 airfoils. As their names imply, both of these Helmut Quaabeck airfoils have 2% camber. One is 8% thick, and one is 8.5% thick. I did some simulation runs, and I can tell you that these airfoils perform very much like the MH32 or the HN-354sr.
According to the CHK Web site, a Phoenix holds the record for the fastest speed run flown in an official competition of 14.70 seconds. Compare this to the fastest speed run at the 2001 F3B World Championships of 15.85 seconds. However, the top-placing Phoenix was 15th at the 2001 F3B World Championships. Placings in most glider contests are still determined 90% by the pilot skills and 10% by the airplane. I quoted the fast time to show that the Phoenix has potential.
The Phoenix's slightly swept-forward wing is in two pieces. The square wing joiner is the "floating" style. This means that the lift forces are transferred to the fuselage via four beefy incidence pins—not the wing joiner. The wing joiner does not even need to touch the fuselage.
The hollow molded wing layup is a carbon D-tube with PVC foam (not Rohacell®) sandwich material. Divinycell is the American equivalent of the PVC foam. The carbon and balsa shear web extends to the carbon spar caps on the outer sandwich skins, transecting the foam. This added complexity gives the spar more effective height. Bending stiffness varies with the square of the height, so every bit helps. The control surfaces also have carbon skins. The large, bottom-hinged flaps help slow the model down for landing.
The hardware pack for the Phoenix is complete. Wiring for the wing servos is already placed in the wings. The builder gets to solder the connectors on. The Phoenix has one 15-millimeter (mm) ballast tube in each wing. If the tail servos are mounted forward, there is also room to add ballast in the fuselage.
Control-surface wipers were not present in the samples ShredAir had received so far. Some of the European molded-glider vendors argue that the weight of the wipers offsets the small drag reduction.
The V-tail is one piece and removable. It nestles into a cradle on the fuselage and is secured from below with one bolt. As the picture shows, there is ample room for radio gear. Dieter Mahlein of ShredAir Inc. is the US importer of the Phoenix. The price is $895 as I write this.
Tom Clarkson created an audio CD to help run the International Hand Launch Glider Festival (IHLGF). The CD has three tracks that can be played to automate the working-time announcements of a hand-launch contest. The CD is for sale through HiLaunch on the Torrey Pines Gulls Web site. Tracks are included for 10-minute, eight-minute, and five-minute working times.
To use the CD, a contest organizer would set up a portable CD player feeding into a public-address (PA) system. The 10-minute track on the CD announces "Three minutes before a 10-minute heat." A minute later it announces "Two minutes before a 10-minute heat." As the start of the working time approaches, the announcing interval gets shorter. It calls out 45, 30, and 25 seconds. It counts down the last 20 seconds then sounds a horn at the start of the working time.
During the working time, the CD announces time left in one-minute intervals. With one minute and 30 seconds left, the frequency of announcements starts increasing much like it did to start the working time. A human could make all these announcements, but the CD is so much easier. It will be one of the best $25 a contest organizer ever spent.
The PA system used at the IHLGF consists of a 100-watt amplifier and four 50-watt PA horns. All equipment was purchased from RadioShack®. For this hardware arrangement, the horns had to be wired with two in series and two in parallel. This makes the impedance of the horns 8 ohms, which the amplifier is expecting. Whatever you do for a system, follow the instructions to correctly match the speaker impedance to the amplifier. The IHLGF got by for years using a 40-watt PA system before purchasing the larger one.
Tom pointed out that if you are going to use an inverter to deliver AC power from DC batteries, it is important to get a high-quality one. He finds that a full sine wave inverter significantly reduced noise in the system. Two winch batteries running the inverter are enough to easily complete a half-day club contest.
I naively tried the CD with a portable stereo system (commonly called a boom box). The boom box played loud enough to hurt my ears in the house, but it is not loud enough to run an HLG contest. It takes a lot of power and/or efficient speakers to project sound over a large airplane field. PA horns are generally much more efficient than regular audio speakers.
The third topic came from Terry Edmonds, who is the US Soaring representative to the Commission of International Aero-Modeling (CIAM). CIAM is the branch of the FAI, which is the world governing body that makes rules for most air sports.
I am including the portion of the rules that deals with the F3J stakes. See the links at the end of the column for Terry's complete report. This is the new section 5.6.8.3.c.
"If towing with a pulley, behind the pulley an unbreakable shield with diameter of minimum 15 cm must be fixed to protect the towline helpers against broken whipping line ends. In the case of towing with a pulley, two helpers have to operate at the pulley and one of the following prevention measures must be taken:
"• The pulley and protective shield must be connected to a 5mm minimum diameter cord arranged in a V, the arms of which must have a length of 1.5 to 3.0 m and with hand loops on each end; or
"• The pulley and protective shield must be connected to the centre of a sufficiently strong yoke of minimum 80 cm length with handholds at each end. In the case of towing with a pulley, the towline end must be attached to a ground anchor, which is fixed by metal ropes to two additional safety pins.
"The length of the main stake must be at least 50 cm from the towline linkage. The safety stakes must be at least 30 cm long. The main stake must be driven into the ground to a depth of at least 40 cm. The towline linkage must not exceed 10 cm above the ground. The ground anchor/dimensions and its setup could look like as shown in the drawing 'Guideline for proven ground anchor setup.'"
Following is an excerpt from Terry's report about the new rule:
"The anchor rule officially will not be in effect until 1-1-03. Sources:
ShredAir, Inc. Box 10093 Eugene OR 97477 (541) 954-6842 http://shredair.com
Phoenix manufacturer: CHK Modelle Hopfengartenweg 15 93057 Regensburg, Germany www.chk-modelle.de/
HLG Timing CD: Hilaunch.com 4415 Caminito Sana #4 San Diego CA 92122 (619) 988-1710 www.hilaunch.com/
Terry Edmonds CIAM report: http://eiss.cnde.iastate.edu/
FAI Web site with official rules: www.fai.org/
Transcribed from original scans by AI. Minor OCR errors may remain.
