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Post by ezza on Aug 17, 2007 22:06:40 GMT 10
I would be keen. Hopefully forecast come true. I will talk to Swoopdown in the morning and see what his plans are. Maybe we will go to Beechmont tomorrow so that you are not tempted to join us?
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Post by sean on Aug 17, 2007 22:10:37 GMT 10
he he, you're right it can be hard to resist. When the weather's good it really sucks missing a day of good DSing.
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Post by sean on Aug 25, 2007 18:39:07 GMT 10
Well, the Griffon has seen the dark side and I liked it! I desparately needed to get outside today after a week being cooped up inside thanks to the rain, so thought I'd check out Bald Knob, even though there were regular heavy showers coming over our house. Fortunately the weather at Bald Knob was good, there was heavy rain north and south but nothing at Bald Knob. The wind must have been about 20kt SE. First thing was to see how the Griffon went ballasted... very well indeed as it turned out! It handled the extra weight so well it left me wishing I'd built it a bit heavier, I can see that it'd handle another few hundred grams no problems. After a short time carving up the front side I realised that all I wanted to do was wind it up on the back side... I'm afraid I've become totally addicted to DSing and nothing else will do now . Pity in a way.... So I checked out the 'Camel Hump' on the SW corner of Bald Knob. It faces SSE so I was expecting the winds to be too east for it to work, the wind was blowing up the front at quite an angle but the back still looked nicely sheltered and still. I threw the Griffon out and the lift on the front side of the hump was actually quite strong. No time to waste, dive for the back side and see what happens. First impressions.. this plane is so solid on the back side, it just carves around requiring very little aileron input and cutting through the turbulence nicely, it was almost too easy! With decent wind speeds were immediately high, I reckon higher than I've been before. The other thing that struck me was how good this spot is to DS -- steep back side and a really well defined shear layer. It was possible to fly the circuits well back and a fair way off the ground and still have a nice clean separation layer to fly through, but you need to go very deep and low to get through it cleanly. With a soft easy landing zone and relatively high DS zone this spot has Opus MC3 written all over it! So everything was in aligniment for a good day's DSing... shiny new very DSable plane, good wind and a good location. I must have flown DS circuits continuously for a good two or more hours, only stopping as the occassional shower passed through. I so wish I had a radar! I estimate the Griffon saw speeds of around 120mph. It looked much much faster than the Bat when it was radared at 92. When a good gust came through the already satisfying noise raised in pitch to become quite a howl, it was then that I knew it was really moving! It seemed to like tight circuits, really banging the turn top and bottom but it also flew nice satisfyingly big circuits too, but they didn't look as fast to me. The plane was rock solid the whole time, not even a hint of flutter and the wings remained dead straight through the high g turns. The only discernible noise crossing the shear layer (apart from the ever present howl) was from the ballast rattling in it's tube. Towards the end of the day I was thinking to myself how happy I was to have DSed all day without incident. I was getting tired and losing concentration but I thought it wouldn't hurt to have "One Last Flight". You guessed it, whack! it went into the backside nose first. Something happened down there, it became turbulent and instead of landing in one piece I kept at it. Unfortunately I couldn't get it to maintain speed on the back and the turbulence just pushed it into the deck. Made a pretty awful sound but there was very little damage. The worst thing was a broken servo arm. A bit of a pain because it means the servo has to be cut out to fix. The nylon bolts sheared nicely leaving the fuse completely undamaged. All easy repairs but it slightly spoiled an otherwise perfect day of DSing. I was so impressed with the Griffon that I'm seriously considering building another, heavier one....
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Post by callun on Aug 25, 2007 19:27:24 GMT 10
Surely you could just fill up the golfshaft with liquid lead
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Post by sean on Aug 25, 2007 20:29:26 GMT 10
I'm thinking more of everything, including larger custom cut wings of a different planform, making a wholey original design raher than a Reaper mod. The more I think about the more I want to do it .
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Post by ezza on Aug 25, 2007 20:50:39 GMT 10
That is awesome Sean! There is nothing like ds'ing at high speed with a plane that can handle it. You don't have to worry about flutter or breaking it with speed. These things track better than any other foamie I have flown. Like you said.....too easy, but very addictive. Shame about the crash but not bad considering you would have done hundreds of laps.
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Post by ezza on Aug 26, 2007 21:26:12 GMT 10
I'm thinking more of everything, including larger custom cut wings of a different planform, making a wholey original design raher than a Reaper mod. The more I think about the more I want to do it . YEAH DO IT SEAN!!! I would love to see what you come up with. Judging by the mods you do to existing models I bet it would be something really special. I would especially want one if you built it. ;D ;D ;D ;D ;D
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Post by sean on Aug 27, 2007 13:09:16 GMT 10
Hey Ezza, plans are afoot! ;D
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Post by sean on Sept 2, 2007 18:31:51 GMT 10
I finished the Griffon's fuse yesterday, painted the nose white and glued the tail in... looks great. Flew it up at Bald Knob and managed to get the CG back further than before, after which it was really banging turns, up elev throw on low rates is about 1mm up and 1mm down yet still plenty of pitch stability. High rates are about double that but completely unnecessary.
Tried some DSing, was doing some circuits with Greg (Bald Knob pres) and whack, hit the top of a tree, almost recovered but not quite. I found it speared into the soft ground almost up to the wing roots, scary stuff, the only thing broken being one nylon bolt. No close in flying with this machine...
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Post by st on Sept 2, 2007 18:50:44 GMT 10
I can't believe how small that throw is - when you see it it is even smaller than it sounds! Total throw is almost as small as the slop in my Bee ;D I guess more throw is required the less smooth and less efficient the airfoil is.
It's a very smooth and well finished plane!
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Post by sean on Sept 2, 2007 19:20:57 GMT 10
Thanks Simon . Yeah, I kept moving the CG back and back and instability never set in, quite surprising. I just measured the CG at 50mm back from the LE! The standard Reaper is supposed to be set at 44-47mm! Any further back and it'll definitely get unstable and servo resolution could become an issue. I reckon this has unleashed a little bit more speed too, and it was maintaing height in the low lift quite easily even when ballasted.
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Post by ezza on Sept 2, 2007 23:04:20 GMT 10
Hi Sean, 50mm! Mine becomes fairly unstable around 48-49mm. I guess that is the difference between a perfect wing and a totally beat up one.
I usually have mine around 47mm and between 2 and 3millimeters of elevator travel. Anymore and it will porpoise.
You have inspired me to rebuild mine. I will do it as soon as I get my JW in the air.
These Reapers can do crazy 'flicks and spins'. Big dive then flip to full rates and yank.
How was the ds groove today? I guess it was easterly up there?
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Post by sean on Sept 2, 2007 23:38:13 GMT 10
Hey Ezza, it's a bit strange, before I painted the nose I got to the unstable porpoising stage with the Cg at about 48mm. This time I adjusted the CG in finer increments by moving a stuck-on weight gradually rearward (it ended up just in front of the fin), so perhaps last time I went from too far forward to too far rearward in one go. Or the difference could just be in the way I measured it... I didn't go to too much trouble to get a perfect measurement. It was still very stable at this setting, no signs of porpoising. It may need a few more flights to really see how it's going, the wind was very light. Haven't explored the stall/spin characteristics yet, I tend to instinctively avoid anything that will cause a snap, but I can say it was banging these really fast F3F style turns without losing too much speed.
DS was slow but very smooth. Just before I crashed it was fairly quick but by the time I got it back out the wind had dropped to the point where it was tough to get enough height to get over to the back. Pretty much a due easterly. I got up there late, it was probably much better earlier int he day.
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Post by sean on Sept 10, 2007 23:26:58 GMT 10
I took some photos of the Griffon this Saturday at Bald Knob. The nose has been painted with acrylic lacquer from a spray can, and the tail has been glued in properly. All that's left to do is finish and install the servo arm covers, which it really needs with the servos sticking out the bottom. Unfortunately Saturday didn't go too well, kept trying to DS when the conditions weren't right for it. I kept getting stuck on the dark side with no airspeed and spearing into the side of the hill. Usually this didn't cause any damage (except for broken nylon bolts) but on one occasion it speared in and must have hit a buried rock. When I pulled it out the tip of the nose was a real mess. I can easily cut the tip off and sand it round but having only just finished the paintjob it wasn't the best thing to see! Before Saturday I'd been trying to fly it like a composite, albeit a composite that can survive the odd heavy crash. But I think for DSing you really need a plane you don't mind crashing to test the back side. It's time to get my Bat back in the air for that purpose! Looking sweet: Looking not so sweet:
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Post by ezza on Sept 10, 2007 23:48:21 GMT 10
Yeah, Sean get that Bat back in the air. Your Griffon is WAY too nice to be flying/ds'ing in dodgy conditions. Try and keep it clean atleast until we can get a radar gun on it.
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