Sunday, 26 May 2013

East Lomond Scottish Summer League Rd2

Went to Scotland yesterday to compete in the SSL at East Lomond, the forecast was good with bright sunshine and light winds and it was a great opportunity to try the Stinger in its first race. An easy 200 mile drive from Lancaster to East Lomond Hill near Falkland only took three and half hours and the first person I met in the car park was fellow southerner Mark Redsell! Shortly after the Scottish lads started turning up and we were shown the short walk up the hill to where we would be flying.

The hill is quite rounded with a steep slope, but no edge to speak of. The landing area was close by with no rotor but you had to be careful not to go too far back as there was a dead lift zone which could suck you into a small gulley. Although there was plenty of wind most of the time, the hill did not generate much lift, so ballasting was difficult and I used less and less as the day wore on and the wind got lighter until the middle of the afternoon when it suddenly got very windy and some of the ballast went back in.

I used the EM turn style throughout the day, but it did not give an advantage over reversal or yank and bank as there was not enough horizontal component of wind force to get any drive out of the corners. The best strategy seemed to be to gain as much height as possible and then fly as tight a course as possible and not make any mistakes and minimise your losses. This was very frustrating as I like to fly a more open and faster style, but this is F3F racing for you.

Occasionally you would get a thermal and this would generate the lift needed for a fast run, this normally resulted in a round win if the thermal came at the right time and position. Many a time I would get a slow run on the slope only to find a big thermal off course near the landing zone. At the lunch break I tried practising with less ballast and I launched into giant sink and all the wind disappeared, a tense five minutes was spent trying to keep airborne while the Stinger dragged its tail about looking sorry for itself while trying to avoid Euan's Cyril who was also struggling. Eventually a life saving thermal came along and dragged us both up from the pit of despair and a hasty retreat to the landing zone was made.

Fortunately the day was run very smoothly by the Scottish lads and we managed to get 14 rounds, in the belief that we would get two discards, only to find out back in the car park that two discards become active after 14 rounds i.e. 15 rounds - doh! Still I was lucky enough to get one of those elusive thermals and pop the Stinger's cherry with its first sub 40 and fastest time of the day. That and a couple of other round wins and I managed to get up to 3rd place, equalling my best finish last time I raced in Scotland last year.

Mark Redsell won although he admitted that he couldn't figure out the best way to fly the hill, trying various turn styles and different racing lines. He was closely followed by Dave Watson in 2nd place who had his brightly coloured Needle 124 flying very well indeed and looked much more settled with it than last time I saw him fly.

The standard of flying from the other guys was very good with minimum carnage and only poor Robert Carson had any damage when he had a radio problem with his Predator 3, Peter Gunning was also flying well however he had to leave early for a lunch date and only returned just as we finished for the day.

Final Score
Mark Redsell
David Watson
Tom Foreman
David Loomes
Mike McCracken
Ewan Maxwell
Craig Maxwell
Ian Stewart
Doug Maxwell
Peter Gunning
Robert Carson

East Lomond SSL Rd2 2013 from Tom Foreman on Vimeo.

Monday, 20 May 2013

Hawes Day Out

Our race at the Hole of Horcum got cancelled yesterday, so Mandy and I decided to go for a BBQ in the Dales on top of Weather Top near Hawes, of course I took the new Stinger with me in case there was any wind.

The day started with a gentle breeze and I first flew empty under the dark clouds before landing and getting the BBQ lit and the Chicken Kebabs cooking. While Mandy and I ate our tasty food the sun came out and the breeze started to freshen up a little so I first tried 3 slugs (240g) and then 5 slugs (400g) of ballast. The Stinger is proving to be one of those slippery models that doesn't need much ballast.

Although not mega lift conditions the thermals came through and every now and again the lift went crazy with good 40 sec air. Flew all afternoon as the conditions were so nice, it makes a change to be warm on the slope edge. Mandy tried video with her fancy new Canon 5D camera rather than the normal Panasonic compact, but with no digital viewfinder, a heavy SLR lens and forgetting to switch on the OIS meant footage was a bit shaky. Still she had fun experimenting even though I had a lot to cut out when it came to editing, still beggars can't be chooser's and I'm thankful for any footage of me. Of course all the good air and fancy aerobatics were missed while para-gliders, walkers and cyclists grabbed all the attention!

Unfortunately a road cyclist had a serious tumble below the front of the slope and a air ambulance was called to whisk him away, fortunately he was wearing his helmet, but it looks like he broke a few bones.

Some big boomer thermals came through and it was possible to speck out and then dive back down with the Stinger screaming away nicely, does very good square edge loops!

Finally it was time to go home, but not before we stopped off at Hawes for some ice cream, it was really warm in the bottom of the valley where Hawe's is located and there was a great holiday atmosphere with everyone sat outside the pubs drinking and eating while admiring the shiny motorbikes and sports cars parked outside, fantastic day out!

Saturday, 18 May 2013

Cyril Repairs

Well this is what happens when you make a mistake and go into the hill at 60mph! Port wing hit the ground first, damaging the wing tip and de-laminating the leading edge and drag spar from the wing skin, fortunately the wing spar survived so the wing is repairable. The Starboard wing had a small amount of de-lamination to the drag spar in a smaller area, and the aileron was damaged, but it survived pretty well apart from the aileron servo being ripped from its mount by the wiring loom.

The model was carrying 1.2Kg of ballast and travelling fast so all this energy was concentrated into the wing joiner, which snapped and destroyed the fuselage into three pieces, taking the ballast tube with it. These parts are beyond repair as all the fuselage internal formers were destroyed, half the ballast went missing as well, probably buried in the hill somewhere, on the positive side the tails and radio gear survived.

So I will have to order a replacement fuselage, nose cone, ballast tube and wing joiner and repair the wings, the photo's show progress thus far, basically I have repaired all the internal structural damage by gluing the skins back to the drag spars and the leading edge. Next will be the surface damage to the port wing tip, port wing root, port flap de-lamination and starboard aileron damage, oh well, will keep me out of mischief!

Thursday, 9 May 2013

Stinger Ballast

Had a go at casting some lead ballast for the Stinger yesterday, this will be carried in the wing joiner and the rear wing pockets.

Eventually I decided to make the moulds out of MDF strip screwed down to a scrap piece of softwood. The problem with the MDF is that it tends to crack very easily when tightening up the screws, so next time I'll probably use something else. I had to decide on a compromise between either an open or closed mould. In the end an open mould was chosen for simplicity and ease of removing the lead slugs, the problem being is controlling the amount of lead during pouring and subsequent bubbles during the cooling, but in the end the final product is fit for purpose although it looks pretty rough.

The wing joiner slugs range in weight between 180 - 160g (the two moulds are slightly different) with the wing pocket slugs at 120g, total wing ballast comes to approximately 1300g plus 580g of fuse ballast equals approximately 1900g of total ballast, giving an all up weight of 4.2Kg.

The next problem is getting it to fit nicely in the wing joiner, the inside of the joiner is quite rough and will need some sanding and filing to get it to fit nicely so that it doesn't get stuck in the heat of competition.

Monday, 6 May 2013

Stinger Maiden

Finally got time to maiden the Stinger today, and boy was it worth the wait, it is very fast and agile! Conditions were very light and thermic and I didn't try any ballast, not that it really needed it, a few hiccups to start with when Paul suggested we check everything was moving in the right direction, I noticed the ailerons were back to front, whoops that would have been a bit of a disaster. Still that's why we check these things, so a few programming adjustments were required before we committed plastic to air.

Paul launched, and straight away she was very nose heavy and needed a lot of up trim and a few clicks of aileron to get her flying straight and true, although I like to have a little down trim bias so that they fly level at speed. Tried the the dive test which was very neutral, crow test suggested it would need a couple more clicks of down elevator compensation and the stall was manageable, but felt uncomfortable with the nose dropping abruptly and the right wing dropping afterwards.

On the course she has a lot of natural pace, similar to the Needle but very agile in the turns, will need to dial in a little less aileron differential next time, but didn't really play with the settings I've chosen. Elevator is very responsive, I can live with it, but might need to tone it down. I'm already running less elevator than recommended as I anticipated she would be responsive, although I don't run any expo.

Landings were very easy, my newly discovered setting where I uncouple flaps from ailerons seems to work wonders. Managed three flights with her, she accelerates well down the straights and felt very grippy for an un-ballasted glider. She is very slippery and quick, but doesn't feel very buoyant, so its not the liftiest of wing sections, but that's probably the trade off to make her so slippery. She makes all the right groaning and moaning noises and responded well to thermal flap (camber). She hasn't earned my trust yet though as she is quite twitchy and feels like you are hanging on to a Tiger's Tail, reminding me of when I first got the Cyril, but once I get to know her more I'm sure we'll be able to do great things. Definitely feels faster and quicker than the Cyril, hopefully find out in a couple of weeks at our next race, just enough time to dial her in and get some wing ballast cast out of lead.

Short video, also with Paul ripping up the slope with his Needle, he's really starting to dial in those EM turns!

Tow Scar Stinger Maiden from Tom Foreman on Vimeo.

Thursday, 2 May 2013

Stinger Build 07 - The End

Well had some fun casting the lead nose weight, tried a new technique, normally I just push the nose into wet sand to make a negative mould to pour the lead into, it works but the fit isn't brilliant. This time I used some plasticine wrapped in cling film to take a positive moulding from the inside of the nose, this was then set into some wet polyfilla and allowed to dry for 24h. I then carefully removed the plasticine to leave an accurate smooth negative in the now dry polyfilla. I had already weighed out my lead at 150g, so got out my little camping stove and an old sauce pan and melted the lead outside because of the poisonous fumes (wearing safety goggles and gloves as well of course). I then got a bit of a shock when I poured my lead into the mould as it immediately erupted flinging molten lead in every direction across the garden! Dam, fortunately I managed to jump out of the way and was OK, but it looks like the mould must have still had moisture in it, plus there is nowhere for the expanding gasses (i.e. steam) to go. Now I know why most casting is done in sand, it is because it is pourous and doesn't suffer from such dangers.

So I went back to the wet sand technique, I still had my plasticine positive which I used with the sand, re-melted fresh lead and this time everything went as expected, with a rough lead nose weight being produced which balances the Stinger perfectly. Lesson learned, don't mess around with polyfilla moulds, takes too long for an impatient builder like me. This means I will have to re-think how I am going to mould the wing joiner ballast out of lead, think I might try some wooden strips on a board next.

So the Stinger is ready to fly although I only have 600g of fuse ballast at the moment, good enough for a maiden though, hopefully get a chance to go up the hills soon. Although the Stinger has probably been the hardest mouldy I've ever built (only the 4th by the way) the resulting model is very good with a high level of stiffness, light weight and general shinyness. The controls are all solid with zero slop, it all fits together fairly well, the starboard wing needs a little fettling to line up the wing dowel. Nose cone is very tight fit, might even be able to get away without taping it on. Finally sussed out the new magnetic switch, works very well, like the bright blue light, it even shines through the white nose cone in dim light, although I doubt I'll be able to see it in daylight. There's a lot more finishing required compared to the Baudis Cyril I built last year, but once you've done the extra work, the quality is to the same high standard. Wouldn't recommend it for a first build though, ARTF it isn't!

Still now we'll have to get it dialled in and setup on the slope and hope it lasts a little longer than the Cyril. Stay tuned for the epic Cyril re-build, although I might just sell some stuff and buy a new wing instead, we'll have to see!