What is F3L?
New provisional FAI class for rudder/elevator/spoiler models launched via hi-starts.
The F3L class — previously known as F3RES — is a new provisional, international soaring competition for models limited to two meter wingspan. This class of plane uses only rudder, elevator, and spoiler controls (RES) and they are constructed mostly of wood. Over the past eight years or so, German RC competitors developed a set of rules that largely were used to form the current provisional rule set. F3L was recently added to the FAI Sporting Code and the 2023 rules can be found starting on page 56 of Volume F3 Radio Control Soaring Model Aircraft. I have linked the document and page in the Resources section below.
F3L kits typically cost somewhere between $200 to $400 making for a much lower than most other RC soaring formats cost of entry class of contest flying. Many modern F3L kits can be built in 40–60 hours or so. This author built his most recent F3L kit, a Yellow Jacket 2M Competition GS (again, see Resources) in a little under two months without making too much of an effort to rush.
F3L models need to be made mostly of wood. Carbon/fiberglass parts can be used for spars, leading edges, joiners, and pushrods. The fuselage can have a carbon/fiberglass tailboom as long as the boom doesn’t extend beyond the last 1/3 of the wing cord but the pod must be made from wood although 1/3 of it can be reinforced with glass/carbon. The pilot doesn’t have to build the model flown and ARFs are allowed.
F3L planes are launched into the air using relatively low-strength high-starts also sometimes called bungees. F3L hi-starts are composed of about 15m of rubber/surgical tubing and about 100m of kite or fishing line. In a contest setting, the hi-starts are provided by the contest organizer and are matched to provide a fairly equal pull when stretched to a common length. The hi-start’s pull distance/strength is specified in the rules. Launches are generally fairly gentle.
The objective of an F3L competition flight is to fly as close to six minutes duration and land the model with the nose close to a predetermined spot on the ground. Competitors are given nine minutes of ‘working time’ where they and other pilots in their flight group must launch their model and try to fly for as close to six minutes as possible. Pilots may make as many flights in the nine minute window as they want but only the last flight’s in the nine minute window is scored. The landing task is fairly generous with 100 points being scored for landing within 0.2m of the landing spot and beyond that points are distributed based the following table:
This short video provides a couple of examples of landing techniques which would have qualified for points under the F3L rules.
F3L entrants compete as part of a team where pilots take turns flying, serving as air reader/timer/helper for a teammate that is flying, and returning the launch lines for in case the pilot that is flying needs to re-launch within the round and prevent line crosses from launch lines of other teams. The team format is ideal for beginners because every contestant in an F3L contest will be put on a team. This means every contestant in an F3L contest will have designated team members to help the new contestant launch the model (if desired), time for the new contestant and other housekeeping tasks.
F3L is a great competition format for new pilots or experienced pilots that would like a relaxed format that rewards building a well flying 2m RES model. This author thinks it is a great format for club or regional RC soaring competition and hopes that this format gains traction regionally and around the world and serves as an entry point for RC glider pilots to try out competition.
Thanks for reading and see you in the launch line-up!
©2023 Ryan Woebkenberg
Resources
- FAI Sporting Code — Volume F3 Radio Control Soaring Model Aircraft — The F3L rules start on page 56 and this link will automatically open the document to this specific page.
- Yellow Jacket 2M Competition GS by Sonoran Laser Art. — This is the aircraft mentioned above. From the website: “The Competition GS wing has a new planform as its more elliptical, lower EDA, with longer mid and short tip panels…”
- F3RES Resources on RCGroups. — An F3L discussion and resources with information on models, hi-starts and other subject.
- DJ Aerotech — Another source of F3L kits but also importantly a source of good quality F3L rubber to make hi-starts.
All images by the author. Read the next article in this issue, return to the previous article in this issue or go to the table of contents. A PDF version of this article, or the entire issue, is available upon request.