Ok, here's the general gist.

I'm 15 years olds and have been running fells for about half a year.
My Dad is 46 years old and has been running fells for over twenty.

On Wednesday nights we train together over distances of about 8 to 10 miles. Being naturally competative and possesing healty amounts of pig-headed stubornness, I set myself the challenge of beating him. I currently train about 60-70 miles a week, mostly just normal hill sessions, but with one session of hill reps and one of interval training. He only trains three times a week, but does longer sessions.

I can generally compete with him on the flats and pull ahead on the climbs, but he destroys me on the downhill sections. I just can't seem to go that fast, he just utterly motors and always finds the best line down a fell, even if we've never done it before. I've heard all the "brakes off brain off" theories for descending and it'd not a fear thing, I just can't get the speed without going into a horrible flapping feet style of running that quickly gets me knackered.

Is it a style thing? Is there an area of training I've missed out on? Is it a kit issue?

Please, this is an appeal to all you seasoned veterans out there, how can i improve my descending, what am i doing wrong?