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Author Topic: High aspect-ratio A6's  (Read 1582 times)
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Olbill
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« Reply #25 on: February 15, 2019, 12:21:38 PM »

The 1/16" heat shrink tubing works nice and you can get it anywhere. Part I like is that it buts up against the hook and slightly covers it, keeps the rubber nice and centered, as the picture shows.

Yes, cocktail straws are also good, I bought a box of 1000 online for $5, pic below (multiple lifetime supply, I'd be happy to bring a few dozen to a contest if you want some!). These are the same as what you show, they go completely over the O-ring and hook, as in your picture, you can also do it without the O-ring if you like, pic below.

Either way you've got a nice stabilized front hookup that probably won't ever tangle in the air. A rear tangle will shorten your flight but a front tangle will stop it.
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raggedflyer
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« Reply #26 on: February 15, 2019, 12:44:02 PM »

I’ve achieved good results using a short length (7 - 10mm) of very thin wall silicone tube which also pushes over and confirms readily to the hook shape.
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Flyguy
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« Reply #27 on: February 15, 2019, 01:01:30 PM »

The 1/16" heat shrink tubing works nice and you can get it anywhere. Part I like is that it buts up against the hook and slightly covers it, keeps the rubber nice and centered, as the picture shows.

Yes, cocktail straws are also good, I bought a box of 1000 online for $5, pic below (multiple lifetime supply, I'd be happy to bring a few dozen to a contest if you want some!). These are the same as what you show, they go completely over the O-ring and hook, as in your picture, you can also do it without the O-ring if you like, pic below.

Either way you've got a nice stabilized front hookup that probably won't ever tangle in the air. A rear tangle will shorten your flight but a front tangle will stop it.

Most definitely, I learned that one the hard way - of course it falls off (without sleeve) on the flight that's your longest so far, which just 'dethermalizes' it right down! sleeve solves that problem.

Might as well make a few comments on the F1L prop testing this week. I made a Leo blade and set the pitch to 25p, did pretty thorough testing this time and put up 7 flights with it. Did OK, but the conclusion is the same as before - it requires heavier rubber to get it up there, and I really had to go to a much higher torque to get it up 28 feet! The part I didn't like was that, with the lower pitch, the RPM was higher, it was around 105 for most flights, whereas my other prop was down to 85. So the curvature might be too much for props with all the area in front of the spar, and lower pitch doesn't appear to solve the problem, as Olbill also found. But this may not be the case for symmetrical blades, given that Leo gets great times. In any case, I'm going back to the regular blade set at 26p and am just trying to make another prop that's as good as my first one, might take a few tries! Would be nice to start focusing more on the flying instead of testing new props every week!
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Flyguy
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« Reply #28 on: April 26, 2019, 01:15:27 PM »

Well I pretty much spent most of the indoor season experimenting with F1L props - different widths, different spars, different pitch, mounted on top of spar, mounted on bottom of spar, 14", 15", you name it! I've settled on the 15" 26p prop, I have one really good one and one almost as good one (after making over a dozen). I've been able to do around 13 1/2 min several times, with 13:42 being the best, so we'll have to pick it up from there next year. First photo is end of the season shot of one of my F1L's - I've gotten good at skimming the lights and didn't lose any planes this year, so I really didn't even need my second F1L! same thing for A6 - I pretty much flew only one of the two 24" A6s.

I've been neglecting the A6's lately, so for the last few sessions I thought I'd finally get around to some side by side comparisons of the 24" and 20", field shot below. I 'retired' the 20" pretty quickly last year because I had the 24" built, but lately I've been thinking that maybe I did that too quickly and should take another look at it. First thing that struck me was that it was very easy to trim, just climbs right up there, no problem with high torque at all. If I was doing high ceiling flying, I might stick with it since it looks easy to get it up to 100' (I wish we had Columbia!). The 24" on the other hand, is trickier to trim, particularly for the burst, and I noticed that Tom also had burst problems all season with his 22", so it's finicky. You can get it trimmed to deal with the burst and climb out, but it's trickier and everything has to be 'just right'. However and most important, I thought the 24" had a nicer cruise, a little slower, and for the few flights I got in, the 24" always had longer times than the 20". Plus I've only gotten to around 6:45 with the 20", even though I haven't flown it much, but have done over 7 min (top of 7:26) with the 24" a bunch of times. The other thing that convinced me is, for two very similar props, the 24" typically has RPM of 340 or lower (down to 320 or less) - but RPM's for the 20" were around 370, just reinforces my conclusion from watching them fly - the 24" flies slower.

So that's where it stands. As far as the high AR stuff goes, I'd recommend that if you want an easy to trim plane, or are doing high ceiling flying (Cat 3 or 4), the 20" is nice, really barrels up there with little trimming effort. However, for 'low' ceiling flying (Cat 1 or 2, and maybe high ceiling), I think the 24" flies a little slower and has the edge. Given that I only have 32' of flying space at Teaneck, I'll stick with the 24"!

I'm usually too focused on flying to get any indoor video, but I recently got part of an F1L flight and the 24" A6 flying last week: https://www.youtube.com/watch?v=6DHsLdXGOks
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Olbill
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« Reply #29 on: April 26, 2019, 02:42:06 PM »

Nice work and nice flights!
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Flyguy
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« Reply #30 on: April 26, 2019, 04:11:01 PM »

Thanks Bill! This is my first year with F1L and I'm really liking it, fun category, flies really nice. You need some twist for a lot of wash-in during high-torque bursts, but once you get it set it just pulls it's way right up there (not as tricky as the 24" A6!).

This is my second year with A6 and it's also a lot of fun, part I like is that it allows for a lot more design flexibility, so I spent last year experimenting with designs, and losing a lot of them as well! I've settled in on the design and will focus more on rubber/winding next year.

I'm thinking about building an F1R, takes me back a bit to my indoor roots. I kind of went backwards indoor-wise - I started years back with F1D (red and gold frames of microfilm all over the basement!) then moved on to EZB and minis - I just like the simpler stuff, plus I have space constraints. But it seems like the F1R is basically a bigger version of a ministick, and it looks like it might be fun (and I think I can do it boron-free as well but we'll see). Plus I still have my old fuselage and boom forms, tungsten, bracing wire, and other F1D stuff (from the 60's!). I think I'll start with a fixed prop (I'm old-fashioned), but another plus is that I have an F1R VP prop hub from Jonathan, so it will be fun to eventually play with that. But that's for the Fall, right now it's time again for the great outdoors!


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Flyguy
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« Reply #31 on: September 23, 2019, 09:39:30 PM »

A few people asked for plans for the 24" high aspect ratio A6, so I posted them in the Builders' Plan Gallery, it's a pdf file with 3 pages, photo of my latest one is below.

A few comments: it was easy to build the 20" version to the 1.2 g minimum, but it's a little trickier for the 24" A6. It's important that the wing is stiff, I'd recommend 5 lb for the wing LE, and lighter, like 4.5, for the TE, and 4lb or under for the stab/fin. I originally put the LE at a 45 degree angle for aerodynamic reasons, but my reasoning now is that the greatest benefit is in terms of stiffness - at 45, the 1/16 sq has the largest cross-section vertically and horizontally, so I think it's stiffer. So now I put all the LE's and TE's at 45 (even for the fin), the last wing seems pretty stiff and the climb under high power was really nice. First time out with the new one last week and it did 7:20.

I also changed the prop slightly in that I glue the two bass pieces at right angles, then when using a 45 degree blade it lies flat relative to the spar. Prop seems to work really well. The plans have some other details.
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Flyguy
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« Reply #32 on: September 24, 2019, 11:02:31 AM »

Oops I just noticed that the weights given on the plan are for the 20" version, I forgot to update them for the 24". The updated weights for the 24" version are shown in the plan photo below, sorry about that!

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