PFK mods for KAP

_MG_7681-2The Conservators House at Clayhithe. Click Pan Pro AutoKAP image taken from a camera suspended under a PFK Nighthawk in Bft5.

It has taken me a good while to warm to the Paul’s Fishing Kites (PFK) Nighthawk from Paul Barnes’s remarkable fishing kite family. The single minded fishing tackle inventor from New Zealand has given the world not just a sky hook for the fishermen of the Southern Ocean but an unstoppable high wind kite for KAP. It is widely used as a lifter in Bft 4 and 5 and it’s rated up to Bft 8 (40 kt).  It out-flies any other kite I have in Bft 5. The problem for me is that at these high wind speeds the airflow is very dirty where I fly ( up to 60m AGL)  and the red arrow tends to smash around the sky like an angry seagull with violent tugs on the line. I have found that giving it a deep lead ( up to 20m) ahead of the camera helps as the line takes up some of the movement from the kite but it still gives the rig a pretty rough ride.

After learning how the spreader spar of a delta kite affects the adaptation of the kite to flow variation from the work of Mike Leduc on Christoph Fokken’s ‘Levitation’ I decided to experiment with ‘softening’ the PFK Nighthawk by replacing its tawa spreader spar with a carbon one. As I use the kiwi kite as a ‘last resort’ I wanted to keep the strength of the spar but introduce more flexibility to try dampen the vibration imparted to the line.

PFK x640The PFK Nighthawk. Stays up in a fresh breeze with a steep flying angle and a bucketing ride for the rig on a razor tight line.

I used a single 864mm (34″) piece Skyshark 8P replacement. It worked, the 8P is much springier than the tawa but needs more effort to bow it between two hands. It’s hard to describe but the carbon is ‘twangier’ than the tawa. The carbon is stiffer and lighter but flexes smoothly. My guess is it’s the faster reaction or recovery of the flexing of the spar that gives the carbon spar the improved response to the pressure variation it has to absorb to keep the kite aloft. In musical terms the carbon has a higher ‘pitch’ than the tawa. It’s a noticeable difference; the line is less jangly when flying the Nighthawk with the carbon spar.

_MG_7588With no image stabilisation on the Eos M reducing vibration is a must.

With no feedback from the AutoKAP rig I fitted a flight recorder to see how good my height estimation was. I need to practice this as I feel happier with a ‘fly and forget rig’ up there in big winds: it reduces the stress of the situation and consequently my kite control is better   with one eye firmly fixed on the swooping kite in front of me and the other looking for upwind weather, safe tie off points, downwind for passing traffic, the rising and falling rig…and my subject.

Altimeter trace 2The altimeter trace over the half hour (33mins) flight. It records the big variation typical of stronger winds, my target height of 60m was never maintained for more than a few minutes. The drop at around 13:54:48 is where I let out more line, the rise is about 20m after which all the variation is due to wind speed until the walk down in 2 steps the first at 14:13 ish and again at 14:17.

07022014 wind speed Windspeed record shows a peak of 21 mph which the PFK handled easily.

_MG_7812The last step of the walkdown: walking the kite back to the tie off at zero altitude.

Discussion on modifying deltas for KAP is here:

http://arch.ced.berkeley.edu/kap/discuss/index.php?p=/discussion/3398/extending-levitation-delta-upper-wind-range/p1

Still hoping for gentler winds,

B

About billboyheritagesurvey

Heritage worker
Gallery | This entry was posted in KAP, Kites and tagged , , . Bookmark the permalink.

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