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And next an Astro Hog?

about to go pick one up

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Bob Cotsford30/10/2013 15:58:22
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A clubmate is 'retiring' and is parting with his fleet, so I've claimed his Flair kit AstroHog. That will take my aerobatic fleet back to 1957, though my 1946 designed Eros still holds the honour of oldest design.

I haven't seen it fly for a while so I'm hoping it is structurally sound. OS46 of some sort, 35MHz rx, Futaba servos.

£50smiley

Anything to watch for on the Flair version?

Edited By Bob Cotsford on 30/10/2013 15:59:06

Braddock, VC30/10/2013 21:15:10
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Yep, that somebody doesn't beat you to it. They are superb. The foam wing version is a little heavier though.

Bob Cotsford31/10/2013 13:11:40
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it was safely collected last night! OS 46 AX, 3001/148s, film covered built up wing. All very nice, inside it looks factory built. Colin made an excellent job of building it from what I can see. There are a couple of patches in the film but I'll probably leave it as is to retain it's 'patina'smiley though I may add some extra trim on the fus. and the balsa pushrods are giving me cause for thought.

Percy Verance31/10/2013 14:17:22
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Nothing to watch for I'm aware of Bob. I never had the Flair one as mine was built from the Sig kit. Good sound model and steady flyer. Surprisingly aerobatic. Super Tigre .61, later replaced by an Irvine .61 in mine.

The Flair one is actually truer to the 1957 original in that it had (has) the tailplane mounted on the underside of the fus. The Sig version has it on top. The original version had quite large inset ailerons, with the Sig version sporting full length strip ailerons. I'm not sure about the trike undercart though. I think the original had the tailwheel, but Sig's version offers the nosewheel mod if the builder fancies it. I didn't.

If the balsa pushrods are 3/8 Bob, I wouldn't worry. However, if they're fairly softish 1/4 square, then replacing them could be worth thinking about. No nasty surprises await Bob, just fly and enjoy.......

Phil 931/10/2013 15:08:10
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4287 forum posts
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nothing wrong with balsa push rods. If made to a good standard they are still a lot better than a long metal push rod. If they are good ones the balsa push rods can be lighter and siffer than a long m2 metal pushrod

Bob Cotsford31/10/2013 16:18:16
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they're more like 1/2" sq, and with the low tail it's pulling for up so should be safe enough. It's just that having avoided balsa pushrods since discovering snakes more than thirty years ago I've developed a phobia about themsurprise

It's got film hinged barn-door ailerons, same as my KwikFli clone which give a lovely screech on a fast rolldevil, and it's taildragger so it does look right.

I can't see it getting a test flight this weekend going on XCWeather's predictions, so I need to stock up on patience.

Braddock, VC31/10/2013 16:50:12
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Balsa push rods are fine, they are nearly matched by carbon fibre pushrods but you can buy a dozen balsa ones for the cost of 1 cf one so, given adequate space, there's no contest.

They also tend not to expand in hot weather, unlike sneks.

Braddock, VC31/10/2013 17:03:18
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Meant to say, be patient it'll be worth it. My flair one flew on a magnum 61 4 stroke so the OS in your one should provide oodles of grunt, might be worth overpropping it with say a grey graupner or bolly 12.5x6 or a 13x6 apc to see how it performs.

I had an old astro hog look alike with an OS 46 fx with a 13x6 master and it performed well, the silence was deafening. On a flypast the servos were audible when I pulled in up.

Percy Verance31/10/2013 19:43:17
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Bob

I'd echo Braddocks sentiments re: pushrods and snakes.

I first used Sullivan snakes about 22 years ago Bob and although I thought them superb at the time, it took me a little while to work out why my model needed constant re-trimming at the start of each flying session.

Sullivan have now introduced a thermally stable (carbon) version Bob, but of course they cost more...... I have some here, but as yet they're untried.

Bob Cotsford31/10/2013 19:52:57
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I've not had any problems with Gold'n'rod snakes over the last 10 years or so, but the Slec ones really are diabolical. The pushrods can stay - for now! The engine is fitted with an 11*6 APC, I use an 11*7 for 46-53s on smaller faster airframes and they get through our 80dBa club test but for this one I think I'll go with the bigger diameter, 13*6 sounds good if I can't find a 13*5.

fly boy331/10/2013 20:47:29
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3637 forum posts
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Hi Bob , I built Boddo's from his plan. Flew like a dream. On another forum its was said to be the best flying model ever. You have a good one there, and if the £50 included the motor you have had a bargain. Cheers.

Phil Green31/10/2013 20:56:18
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1552 forum posts
315 photos

Mine has a standard sized servo (S148) actually mounted on the tailplane Bob so no pushrod as such.

Star-Pig_tailplane.jpg

 

Edited By Phil Green on 31/10/2013 21:00:15

Bob Cotsford31/10/2013 21:39:59
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I saw a join in the film in front of the tailplane and having seen how yours detaches I can see the split line under the film on mine. I guess Colin decided to glue it on permanently. That's a neat location to keep the servo hidden Phil.

And yes, £50 rtf, except that I didn't take the Futaba 35MHz receiver as I'm all FrSky 2.4.

I'm finding a couple of little maintenance jobs, threadlocking screws, a drop of cyno to harden up around the elevator joiner, bit of tube to secure clevises - that sort of thing, but nothing remotely worrying.

One question - or maybe two - suggested movements and CofG position anyone? Currently I've got about 10/20mm elevator, 20/35mm rudder and 15/20mm on the barn door ailerons with a lot of diff (all as low/high rates). This was just copying the model setup on my Taranis from a Wot4 and renaming it. I haven't checked where it balances as I know Colin flew it ok not so long ago and I've only substituted the Rx.

Braddock, VC31/10/2013 22:19:29
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Straight from the manual of the kit I just bought from als hobbies, rudder 38mm e/w at widest part of rudder; ele 16 mm e/w ditto foam wing ails 8mm up, 5mm down, built up wing 16mm up 9 mm down.

C of G 100mm from l/e of wing.v slightly nose down.

Now one of Dud's tips two large marbles placed in the necks of two beer bottles, both marbles and beer bottles need to be identical, balance model on those beats the great planes c of g thingy any day!

Martin McIntosh31/10/2013 23:05:42
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My tuppenny worth on this. Snakes are hideous things especially the ones available today and should only be used on throttle. They generally have slop in them unless run in a straight line. I reverted to hard balsa many years ago but now use carbon tubes. You just need a little ingenuity to fix threaded rod to each end. No point in buying modern high resolution servos if there is play in the linkage. This is the more likely cause of trim change since a plastic or metal inner core cannot possibly vary in length measurably over the short lengths involved.

Bob Cotsford01/11/2013 08:31:43
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8256 forum posts
454 photos

Sorry Martin, I think you are wrong on snakes on one point, I've had some (NOT Gold'n'rods) where temperature changes caused all sorts of trim changes because the inner and outer where different plastics with very different coefficients of expansion. The Sullivan ones available today are very good in this respectwink

I do agree that it's hard to beat carbon tubes for pushrods but I've not had problems using 30" and longer snakes as long as they are good quality and as you say, keeping them as straight as possible. Brace them to the structure every foot or so and at both ends. The old method of driving two ailerons from a central servo using snakes bent through 90 degrees was a complete joke.

Thanks for the specs Braddock, it's not a million miles off then.

I have found one disturbing feature - the aileron servos are held in by some nasty brackets secured by screws into soft 1/4 balsa plates. A good waggle a la pre-flight check and the brackets flex letting the servo move rather disturingly. Oops!

Martyn K01/11/2013 12:38:24
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5041 forum posts
3677 photos

I like the idea of the detachable tailplane. I need to do a bit of surgery on mine this winter to repair a cracked spar. I may build a new tailplane and adopt the rear servo idea.

I like that a lot

Regarding snakes. I am using Golden Rods on my Magic. I wish that concerns about these had been flagged before I sheeted up the bottom of the fus..

Martyn

Bob Cotsford01/11/2013 14:01:02
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8256 forum posts
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Martyn, my 10lb SuperSkybolt with OS1.20Surpass uses individual snakes for each elevator half, so does the King Altair, Tornado, Super Chipmunk etc. etc. and I've got several models with one G'nR driving elevators, non exhibit noticable trim change from summer to winter - it will be fine.

Percy Verance01/11/2013 14:32:42
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8108 forum posts
155 photos

Definately a neat solution to hiding the elevator servo there. Keeps the linkage nice and short too. Reminds me a bit of the Ben Buckle Super 60 tailplane arrangement. That fits on from the underside too. I'd have never thought of mounting a servo there though.

fly boy301/11/2013 17:06:24
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3637 forum posts
22 photos

Hi Phil, like the idea of internal position of elevator servo, bit cannot see from photo how it is attached to elevator horn ? Cheers

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