An Icon Goes Red

ChocoFly 1/3rd-scale ASW 17 takes to the skies over the UK.

Most people who fly model planes do so because they love aeroplanes. We all have iconic planes we desire to own and fly. Still today at 58 if I hear the sound of a Merlin engine approaching I run out into the garden to see if it is a Spitfire going overhead.

Talking to Sean Bannister and David Woods at the excellent Ivinghoe Soaring Association (ISA) Christmas Lunch, David mentioned to Sean that I had purchased a 1/3rd-scale model of the ASW 17. Sean’s eyes lit up and we went into a discussion about George Lee’s exploits winning the World Gliding Championship in the late 70’s with the ASW 17.

In the UK the ISA is a famous slope soaring club north of the UK capital London (see Resources, below, for link). It has been fortunate to have many alumni who have made significant contributions to our sport. Sean Bannister designed and competed with his Algebra designs in five F3B World Championships before the explosion of moulded gliders in the class. His design and flying credentials are legend in the UK for many of us and his influence and inspiration reach far further than he realises. Likewise David Woods and his brother Graham have had a massive impact on the soaring landscape of the UK, including designs and construction techniques that have expanded the performance envelope. See Resources below for many video examples found on their Favonius website.

The full-size plane was designed and manufactured by Schleicher and was billed as an evolution of the ASW 12. In reality it was a ground breaking plane in having six wing control surfaces with the attendant ability to have variable camber across the complete wing. There were 55 made and it went on to break many world records.

Like Sean, I love the shape of full-size gliders. However, I have never really had a huge desire to own a scale model of these beautiful planes despite looking like they have been sculpted by the wind.

People ask me why, and it boils down to a few key areas. As construction techniques improved large scale gliders became possible to build and in the 80’s we saw an influx of models from Europe. Planes such as the Wik Astir. These models used copies of the sections from their full-size counter parts. Despite the moulded construction and high performance sections they didn’t actually fly that well. Models were not strong enough and the sections did not translate well into the lower Reynolds numbers at which models operate.

Having flown a few scale planes in the 80’s I found them very underwhelming. After a few low passes and loops as crowd pleasers that was it.

We move on 35 years and things are different. Moulded construction techniques and materials have moved on to such an extent that modern model planes are considerably stronger than in the 80s. Plus the designers have now started making scale models with wing sections purpose-made for the Reynolds Numbers of model flying rather than persisting with the scale section.

Why would I want one then? Apart from the appeal of the owning such beautiful and majestic aeroplanes, we have seen the advent of the competition class of GPS Triangle Racing. Much has been written about this discipline of model flying so I will not go into too much detail. A quick summary would be using GPS technology models fly tasks in the same way as a full-size glider does. A triangle course is used and the objective is to do the most laps you can from a set launch height and in a set time — that is distance flying.

As with full-size gliding there are different classes controlled by the size of the glider. In model GPS task flying they are Light, Sports and Scale classes. Having dabbled in Sports class I thought it time to step up to Scale class.

Building

Without question this is the most complicated model I have undertaken. Despite being moulded, the ASW 17 needs to have the radio and ‘front electric sustainer’ (FES) system installed. So “an electric motor and propellor” I hear you say. It is a little more than that. It is a removable propeller so you can fly the plane as a glider as well via aerotow.

Having received the plane just before a trip to Spain to fly Sports class GPS I thought, “expert advice is required here”. David Woods was contacted and I took the plane over to David for a survey and view on how to do things. As there were no building instructions we turned to the internet and looked at several sites, from which we have cribbed some great ideas we have used before when it comes to installations of radio and motors.

One of the these sites is CMS Modell. We found two build logs on the ASW 17, with one being to the exact specification we were planning including the extra complication of water ballast for GPS Triangle Racing — see Resources at the end of this article for the relevant link.

It was decided that getting the plane ready for Spain was impossible. David suggested I leave the plane with him whilst I was away. Dave offered to do some planning and work out the best way to go about things.

On my return David had used his time to complete some of the major tasks of the install. Despite both of us then working on the final parts of the build we spent another two weeks, with both of us, working on the airframe to get the plane into flying condition. This did not include installing the water ballast which we decided to do after test flying.

Test Flying and Trimming

Test flying was done at the Phoenix Club, London Colney, UK which has a good sized field and a permit to fly large models up to an altitude of 430m.

Having spent time balancing the model with a digital CoG scale and using ChocoFly’s set up sheet the first flight was very straight forward, only a few clicks of down trim required. After a few set up hiccups a good trim setting was found. So good in fact was the set up that on the second flight two climbs were achieved and some practice triangles done on the course.

It was obvious that the plane needed water or the wing ballast in place as it was flying so slowly and floating along like a thermal soarer. One issue which was encountered was the lack of elevator authority on landing at low speed. This has now been cured after further flights by discovering that excessive down throw on the inboard flaps as part of the crow set up was causing a blanking effect over the tailplane.

Back to the workshop where David and I then fitted the water ballast tank which was a fiddly and complicated job. There were many proof of concepts on how to do it before we finally cracked it. Working as a two-man team was almost essential for this task. I must thank David for all of his hard work, years of aeromodelling knowledge and time to help me get this challenging project off the ground. As mentioned earlier he broke the back of the project whilst I was having fun in a warm and sunny Spain. I returned home to help with the final bits.

Water ballast installed, we could now add 3.2kg of weight to the plane. On a very calm day in December we flew the plane with an all up weight close to 18.5kg. To give you an idea of the effect of the ballast I flew one flight dry with a weight of 15.2kg. I did four laps in still air and averaged 62.8kph. Ballasted to 18.5kg I was able to fly four laps again but with an average speed of 94.6kph.

Being able to dump the ballast before landing is a great asset and does make landing easier and more relaxed.

Conclusion

In a way, boring and an anticlimax. Flying the ASW 17 is so easy and because of its size and weight it literally flies hands off for long periods of time. It has incredible speed and glide abilities and despite being over 100g/dm² responds to lift like a much smaller, lightly loaded model. It would be easy to get complacent — take offs and landings need 100% concentration as the plane does cover considerable distances very quickly.

This model design won the last Scale Class GPS World Masters flown in 2019 and its pedigree shines through. Later in the year I hope to compete in the Scale Class European Masters against the some of the best GPS Triangle pilots in the world.

Hopefully I can do the ASW 17 justice.

©2022 Greg Lewis

Resources

• ChocoFly ASW 17 — company website.
• Ivinghoe Soaring Association — “one of the largest R/C glider groups in the UK, with approximately 140 members. Our activities include slope soaring at Ivinghoe Beacon, and flat field soaring at a private field”
• Favonius — David and Graham Woods website which has lots of great videos of their designs.
• Assembling and Flying the ASW 17 — a brief (2:34) video shot by David Woods featuring the aircraft which is the subject of this article.
• Build Log from CMS Modell Flugzeug
• GPS Triangle Racing Training Weekend — John Greenfield’s event coming up April 2nd and 3rd, 2022.
• GPS Triangle Racing at Radioglide — “We have secured a slot in the Radioglide which takes place on the Queens Jubilee Bank Holiday weekend. Location is Buckminster and the date is 5th of June, 2022. We will be flying Light and Sports class in slots…”

All images are a collaboration by the author and Guy Lucas. 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.