C-Fly

The 2011 trials continued into November, fortunately it was a mild autumn! For the last series of trials the Weymouth & Portland National Sailing Academy (WPNSA) kindly hosted us for two weeks. The extensive and sheltered harbour ensured that we could maximise our time on the water and carry out trials in flat water as most of the sailing to date has been in offshore conditions in the channel. The flat water conditions allowed us to collect data on the hydrofoil performance under steady conditions without the added complexity produced by sailing in waves. During some of these trials we used classical visualisation techniques as used in towing tanks by applying appropriate viscosity grease to the foils and observing the flow pattern after each run. This proved remarkably successful.

Of course from the WPNSA it was also quick to get out into the channel for rough water trials and we had some exhilarating sailing in reasonably significant waves of 1.5 to 2m as the wind was generally southerly and blowing straight into Weymouth bay. We are now going to spend the winter analysing the data from the 2011 trials and are carrying out some work to further reduce the drag of the foils.

The first series of sailing trials have been successfully completed this year and there were good winds for plenty of fast hydrofoiling. There was a lot of work for Nigel to commission the instrumentation system and the inevitable teething problems once we were using the system in anger. However overall the instrumentation system was 90% operational which was a good result for the first use of the system and we have a way forward on all the remaining issues. We were let down by some of the linear transducers which failed very early in the trials owing to water ingress. We have selected alternative rotary sensors and are engineering the changes to the mechanisms as we speak. We have a huge amount of data now on the hydrofoil loads in a range of conditions and sea states and are working our way through the analysis. In parallel the planning starts for the next set of trials.

Most of the instrumentation hardware has been delivered and we are starting to manufacture the wiring looms and attach the strain gauges to the structure. A big thank you to Tacktick who have kindly provided their wireless wind instrumentation and displays in support of the project. We will be using their wireless interface unit to create a link with the GPS and datalogging system so that we have one seamless system for all performance and structural data. We will also be fitting a new camera mounting system that can be rigged ahead of the boat to video the front foils for hydrodynamic analysis.

The design of the instrumentation and logging system is progressing well. The objectives are more comprehensive structural load data and better measured wind data with which to analyse sailing performance. Loads measured using strain gauges will include the hydrodynamic forces on the hydrofoils.

We have been undertaking a review of the structure that supports the canard hydrofoils. This is a complex area because not only must it support the significant loads from the hydrofoils but also incorporates the steering and hydrofoil retraction mechanisms. Some of the deflections we are measuring during sailing are higher than we would like and this review will identify areas where we can improve the design.

The team are wrapping up the season's trials and preparing for a programme of work through the winter to refine C-FLY Coastal. A major objective is to design and install a much more comprehensive instrumentation and logging system on board.

The team report that it was an exciting few days exhibiting C-FLY Coastal as part of the EXTREME SAILING SERIES at Cowes. The weather didn't allow foiling on all the planned days but there was plenty of fun and excitement for the team and the spectators. Gybing close inshore at Egypt Point, having foiled through the Cowes racing fleet coming up the Solent, was an experience, and demonstrated the versatility and practicality of the concept.

Credit: P. Wyeth		Credit: P. Wyeth

The C-FLY team have been invited to demonstrate C-FLY Coastal as part of the EXTREME SAILING SERIES event at Cowes. This will showcase the possible future of extreme sailing and the technological developments taking place in the sailing industry.

Tow trials completed on the 5 July and data logged for analysis later. Conditions were OK but not perfect, with a small residual swell working into the bay. Carried out these trials with not only the sails down but the whole rig removed so we do not need to make any allowance for the mast and rigging drag in the analysis.

Sailing trials going well but weather a little light for full foiling at times. However this does allow us to enjoy the excellent hullborne performance and handling of the boat. Reaching along hullborne the helm can let go of the tiller for minutes at a time as the boat tracks so well and is so well balanced.

With l'Hydroptere based in Cowes for the week we took the opportunity to meet up with the l'Hydroptere team, thanks Paul for the invitation to the BBQ! (Paul Larson, Sailrocket pilot) We had the privilege of foiling in the company of l'Hydroptere in the Solent. The restricted size of the Solent and the respective speeds of l'Hydroptere and C-FLY made lining up a little tricky but it was a great occasion. A meeting of David and Goliath! Despite the great difference is scale we were very pleased with the performance of C-FLY Coastal with respect to l'Hydroptere.

Credit: H Darvelid		Credit:H Darvelid

Preparations for this seasons sailing trials are well underway. We will launch this month and have a comprehensive sailing programme to work through and plan to complete further tow trials as well to evaluate the latest improvements to the canard hydrofoils. The tow trials are a very effective way of taking the variables associated with the rig out of the equation and allow us to accurately measure the lift and drag of the hydrofoils and the displacement drag of the hulls with the foils raised.

January 2010 Detailed modifications are being made to the superventilated canard hydrofoil section to further improve performance. These new features will assist with maintaining stable ventilation and reduce drag.