by Henryk Kobylanski and Neil Spencer –
Aerotowing is the process of using a powered aircraft to tow a sailplane into the air. As with the full size, aero modelers also use the same system to launch their scale sailplanes and release them at heights that allow thermal flight when conditions are right.
Over the past 10 years aerotowing has been growing in popularity in the scale soaring community due to the following factors:
- It is usually safer for maiden flights than the slope and is generally less hazardous for the models when landing
- It generally allows for less traveling time as most model airfields can be utilized
- Less weather dependence compared to slope flying
- When organized correctly, more people can be flying at the same time than on a slope
With this growth in popularity, there also comes the inevitable need for better management of aerotowing events. In this article, we try and cover the main areas that influence an aerotow event and in doing so hopefully make it a fun and safe affair.
If anyone has comments or suggestions for additions to this article, feel free to email us here
Basic Requirements
Club affiliation and insurance
With all events in the sport of radio control soaring, there is an expectation that you are a paid up member of a club and have current insurance with the relevant state and/or national body. The positive reasons behind being a member are too many to go into here, but if you are new to an event, do not be offended if you are asked to show your ticket… and don’t be afraid to ask if you are not sure that someone has theirs.
There may be other local requirements at an event like heavy model inspection or radio certification, so please check any local requirements before you start flying.
Operational Practices
1. The Pilot Briefing
To ensure that all participants have an enjoyable and safe day’s flying, a pilot’s briefing is recommended before getting under way. The following are important items that should be covered. Regular events could benefit from printed or on-line guidelines so that new participants and visitors can gain an understanding of the procedures in advance.
During the briefing the following items should be clearly covered and specified:
- Local requirements like heavy model inspections, required endorsements or no-fly areas.
- Launching, Landing & Pilot areas
- Glider Queue
- Tug pit area
- Glider pit area
- Frequency Control System/Transmitter Pound
- Emergency procedures
The launching/landing strip (in most cases) will be defined by the location and the wind direction. In addition to the basic strip setup, procedures should be defined for queuing and hooking up gliders ready for launch.
Tug and glider pits should be a safe distance from the active runway and if possible, it is a good idea to keep glider and tug pits separate. The glider queue should be close to the designated launch area, but a safe distance from the strip. No gliders should be in the launch queue unless they have a loop ready in their tow release and all radio and control functions have been checked.
The glider pilot flying area (as opposed to the launch area) should be clearly defined and it is a good idea to have someone available to guide glider pilots into that area after the release from tow. This could be something the safety officer could help with if one is in operation.
Other items that should be included in the briefing include the frequency control system, specific ground operating & safety procedures, airborne procedures and emergency procedures (e.g. what is expected of a pilot if he/she experiences a loss of control etc).
2. Key personnel & use of observers
It is highly desirable to assign one or more coordinators to manage the proceedings and to provide an initial pilot’s briefing. If no coordinators have been assigned to the event then the tug pilots, or an appropriate local club member, should take responsibility to agree appropriate operating practices and to nominate observers to assist with management of the activities.
Wherever possible, each tow should have an observer for the glider pilot.
Whenever possible the tug pilots should be supported by one or more safety officers who manage the active runway and provide take-off and landing clearances for the tugs. The safety officer/s has the responsibility of managing everything that happens inside the control box, and also on approach to the strip. If a lot of planes are landing at once, the safety officer’s role is to prioritize and co-ordinate the landings to avoid any mishaps by clearly communicating with all the pilots involved. When a safety officer is in use, no other person should be shouting commands to anyone.
Safety Officer’s role:
- To wear a bright colored vest for easy identification (usually available as construction site high visibility vests)
- Manage the airspace giving priority to landing gliders then tugs
- Provide hold/take off clearance as required
- Manage the flight line and pilot areas.
- Give assistance to a distressed pilot only if no one else is available to render assistance. Otherwise the Safety officer would make sure the strip is clear for an emergency landing.
- In the case of disputes regarding operational procedures, the safety officer would refer to the operations manager or senior club representative for clarification.
NOTE: It is imperative that the safety officer must not be distracted with hooking up gliders or getting involved with the setup and operation of gliders or tug.
3. The Tow
Hooking up – be ready and be close by
Nothing is more annoying for all pilots concerned than a glider at the front of the queue and the glider pilot is not ready. If your glider is in the queue:
- stay close to the queue ready for your turn
- have a loop inserted in your tow release ready for hook up
- have all of your controls and gear checked before you place you glider in the queue – at hook up, the only thing you should be doing is a final pre-flight check that all surfaces are working correctly
- if a token or donation system is being used, have your token/donation ready
Making a tug wait is making the tug’s engine get hot (and probably the other pilots in the queue!).
Calling out your intentions
If there is a helper hooking you up they have two calls two make:
- When the line is hooked up and they are out of the way they will call to the tug pilot “hooked up” or “take up the slack”
- Holding the wing tip (if desired by the glider pilot), they will call ”ready”
The Tug pilot will ask the glider pilot if they are ready and a good additional question is for the tug pilot to ask the glider pilot “are they wiggling” to confirm that the glider controls are functioning. The tug pilot will then call out aloud “taking off”. Some Tug pilots like to give the sailplane pilot a countdown to launch “OK, 3, 2, 1….”
Talk to the tug pilot when on tow.
Towing is joint activity between tug and glider pilots. You both need to be able to easily talk to each other. With all the other ambient noise, this will require you to stand reasonably close to each other. Pilots are not mind readers! Notification of turns, speed and climb angle, release preparation and problems in flight all have to be communicated between each other concisely and quickly.
When you have reached the desired launch height or for any other operational reason, the glider pilot should notify the tug pilot that he is about to release. The tug pilot will usually reduce throttle to lower tension on the tow line as this reduces the effort required by the tow release mechanism.
Providing local circumstances permit, after the release, as per normal full size convention, the glider pilot turns right and the tug left.
Most tugs are in high demand so a fast decent is usual after release therefore the glider pilot MUST confirm that the tow has released before advising the tug pilot – if this is not done a descending tug may prevent release due to the high load on the release mechanism.
Pilots stay together
After release from your tow, make your way to the designated pilot area. This will be ensure that all pilots are within talking proximity of each other and can be easily identified by the safety officer. If someone is having trouble, all other pilots need to be aware of this.
When in trouble!!!
The first thing to do is let everyone else know you are in trouble. Then keep letting people know what is happening.
That way all other pilots can clear the airspace allowing you to deal with the situation. If you are still on tow, the tug pilot may be able to assist you in regaining control or alternatively release the tow line from the tug. If there are nominated emergency procedures in place do your best to follow them.
4. Flying
Number and type of models in the air
No matter how vast the area is that you are flying in, it can get crowded very quickly. Limit the number of gliders in the air to what is reasonable for the conditions and the size of the sailplanes or as defined by any local rules – two half scale sailplanes can take up a lot of sky!
Observers
Aerotow by its nature means that in great conditions, your sailplane can become a spec in the sky, no matter what its scale. There are always times you may need to look away and it only takes one distraction to lose sight of your model. When flying in big air, or even better, whenever you fly aerotow, make sure you have someone who can be your second set of eyes. Too often beautiful sailplanes have been lost when the pilot accidentally starts flying someone else’s model.
Thermaling guidelines
A lot of scale pilots do not realize that there are guidelines to follow when soaring. If a pilot is already in a thermal, and you fly into that thermal, you should start your turn in the same direction as the pilot already there. A sailplane in a thermal turn has right of way, so make sure you give them a wide birth if you are crossing their path. It is your responsibility to be aware of what is in front of your model.
Aerobatics – where & when
Some pilots enjoy putting their sailplanes through their paces with aerobatics. As with all procedures in an aerotow event, you are required to call out your intentions to do aerobatics. Performing aerobatics in airspace where others are thermalling, or in the circuit area, can be very distracting, especially without any prior notice.
If a designated area has not been specified in the briefing, make sure that you advise all pilots where you are doing your aerobatics.
Beat-ups on the strip require a call well in advance of the maneuver. Be aware, any landing aircraft have priority over your beat-up. If a safety officer is present, do not conduct the beat-up without the safety officer’s consent. When conducting the beat-up, make sure you fly to the opposite side of the strip away from the pilots and public. A large sailplane at high speeds can cover a great distance in the event of a mishap.
5. Landing
Calling out your intentions
Whether there is a safety officer or just a small group of pilots, if you do not let everyone know you are landing, then no one can give you priority.
Always call out your intentions in advance so that last minute conflicts are avoided.
Who has right of way?
In a properly set up strip, the sailplanes have priority in the landing circuit and tugs should hold off until the strip is clear.
If a tug pilot calls dead stick, then he has priority over the sailplanes as he has less time than a sailplane to land. If a safety officer is present, they will prioritize landings so be aware of their calls.
Retrieving your model
When your model comes to a stop, wait till the strip is clear of any other approaching aircraft, call “on the strip”, or get clearance from the safety officer, and then proceed to retrieve your sailplane.
DO NOT do anything to your model until you have cleared the strip. Only then should you switch off receivers or look at problems etc.
6. Suggested Aerotow Strip Layout
The Launch Box System
The following layouts have proven to work well in most situations, and provide for an efficient and safe aerotow event. Known as the Box system, a box is outlined with witch’s hats or similar, approximately 10 meters square. The head of the box sits flush to the strip running parallel with the active runway. Depending on the wind direction, the launches are conducted on the up wind side of the box parallel with the strip. The tug and launching sailplane pilots stand on the up wind corner closest to the strip.
Once released, sailplane pilots move to flying pilot area for soaring flight. When landing, the pilots move to the Landing Pilot area which should be at the down wind end of the pilot area. This allows landing pilots to have a clear view of the strip and the approach to landing. The Sailplane launch queue comes in from the bottom side of the launch box, just below the hook up area. No pilot should be on the active runway other than to retrieve their aircraft. This would be coordinated by the safety officer. Refer figure 1 for layout.
If more than one tug is in operation, the box can be extended in its height to encompass a tug waiting area and two launch points – figure 2
If strip area is at a premium, then the Launch area can be angled back towards the main strip. figure 3
