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Indoor Free Flight Forum => A-6, P-24 => Topic started by: Flyguy on January 30, 2019, 06:20:20 PM



Title: High aspect-ratio A6's
Post by: Flyguy on January 30, 2019, 06:20:20 PM
Thought I'd post a few things on my A6 progress, started in the 'trying to get back into indoor' thread. Some other club members are also thinking of or are building high AR A6's, so I'll try to get some other pics as well; I also know a few people here mentioned trying it, feel free to post if you like.

I'm continuing this year with my 24" A6, AR of 19.2; I built a second one, though I'm flying a lot more carefully this year! The pictures show my second A6 (same as the first one), came out pretty much on target at 1.19g, like the first one. The first one has consistently done 6:30+ (max of 6:53) the last few flying sessions, so I've been trying to break the '7 min barrier'. I won't lie - I'm pretty excited about today's results.

Flying was a little tricky because the air was choppy, thanks to the record cold, nevertheless the first test flight was 5:47 (20' altitude) followed by a full flight (up to 32') of 7:00 min, finally! I was celebrating that flight and thought I'd squeeze in one last (third) flight (had to leave early today), and that one was 7:26, woohoo! Neither flight went above 32 feet - I've learned the hard way (last year) that going above that is the kiss of death at this site, so I stay below the lights these days if possible. So I'm very happy, though I think that might be approaching the limit at this site (I thought 7 min was), though maybe on a day with a little warmer air... plus I should probably pay attention to the rubber quality, I'm just using whatever I have on hand, can't really do much else (any way to get the legendary 99 or 06 stuff? I pretty much just have 2018). Of course I'll keep doing a little experimenting, but I'm very happy to finally shatter that 7 min barrier that has been haunting me! The high AR A6 seems to have potential.


Title: Re: High aspect-ratio A6's
Post by: Flyguy on January 31, 2019, 11:51:37 AM
I'm making the prop shafts a little differently these days. For the first way, I get some 3/16" x .032 bass strips from the local art store. I then drilled a .012 hole in the center - I have a block I made a few cuts in and I use the one that seems to give the straightest hole, it's a little tricky and you need magnifying glasses, but with a few tries I could get a few good ones, i.e., goes in in the center and comes out at the center. Then I left a 1/32" hub in the center and sanded the rest down to .021, that part is a pain and takes a little time, you have to be careful and check frequently. The only good part is that when done, you can then slice off three 1/16" spars that are ready to go. The top prop in the pics below show this type of spar, you can see that it's been drilled in the center.

Recently I found that you can buy .021" bass strips on the net by doing a search on 'scale lumber', so I tried the overlap approach that Olbill uses. In this case, all you have to do is cut two strips. I then fully form the front wire, including the 90 bend at the front. Then I lightly push the wire on the bass so that it makes a small indent. Then I lay the wire on one strip, put a dot of white glue on it, and then put the other strip overlapping on top, I put it against a ruler to keep it straight and weigh it down, and bango you're done. When dry, I hit the front of the wire with some thinned ambroid. Part I like about this approach is that it's easy and fast, no lengthy sanding! Bottom prop in the pics shows this type of prop.

I've flown dozens of flights with both types of spars and haven't noticed any difference as of yet (the 7:26 flight used the overlapping spar).



Title: Re: High aspect-ratio A6's
Post by: Olbill on January 31, 2019, 11:57:09 AM
Impressive work and results!

I make almost all props with separate spars joined at the middle. It's very easy to get matching properties with the spar halves this way. The only exception is my carbon rod LPP spar that has to be made in one piece.


Title: Re: High aspect-ratio A6's
Post by: Flyguy on January 31, 2019, 12:25:47 PM
Thanks Bill, yes I agree that you can get nice matching using the spar halves, though the one piece A6 spars also seem to work nice, its just that I always go for the laziest approach, so my sanding one piece A6 spars days are over!

The one I'm still debating about though is for F1L. I like that you can match the two halves by weight, along with flex, so I've made a few that way. However sometimes I get a really nice straight strip and so I've made a few where it's just one piece, tapered towards the tips. The top spar in the photo below is an example, the bottom spar is actually two pieces, but you can't see it because I wrap the middle with a little white tissue at the end, didn't do that for the top spar yet. You can still check each 'half' for thickness and flex, but not for weight. Both ways are just as easy in this case, because you're sanding the spars either way. I like that the one piece approach saves a gluing step, but either way in this case seems good. Haven't noticed any differences flying-wise so far, either way these high-flaring F1L props are tricky!


Title: Re: High aspect-ratio A6's
Post by: Olbill on January 31, 2019, 01:28:56 PM
I just got a Leo F1L pitch block from Mike Kirda. I'm going to reform some symmetrical blades on the new block and see how that compares to my flaring props.


Title: Re: High aspect-ratio A6's
Post by: Olbill on January 31, 2019, 01:41:16 PM
How about bringing your models to Kibbie this year? Don Slusarczyk (Cat 2 record holder) and I will be there along with Andrew Tagliafico and maybe a few other A-6 fliers.


Title: Re: High aspect-ratio A6's
Post by: Olbill on January 31, 2019, 02:26:58 PM
There's one other advantage to separate prop spars for F1L. The grain direction in the spars will make them stiffer in one direction than the other. When you build with separate spar halves you can orient the grain in the same direction in both spars.


Title: Re: High aspect-ratio A6's
Post by: Flyguy on January 31, 2019, 06:36:53 PM
I just got a Leo F1L pitch block from Mike Kirda. I'm going to reform some symmetrical blades on the new block and see how that compares to my flaring props.


We're on the same track, I got Leo's pitch block from Mike a few weeks back and have made two props with it so far, talked with Mike about it a little. All my area is in front of the blade, picture below, you can see that the blades have a lot of curvature. The block is 23p, then I set the blades rotated up to 28p and compared that to a 28p prop and I thought it was good. However the best prop I have so far was formed on a 28 block and set at 26p, so who knows, and they are all actually pretty close - I've been consistently doing, in Cat II, over 12 min with either Leo's prop or my other props, so I don't have any verdict at this point, I'll continue to do some tests. Bill - it would be extremely interesting to hear your results when you try it, though it's probably different for symmetrical blades, but please post on that, I've been wondering about it myself and was thinking of starting a thread on that reporting what I found.


Title: Re: High aspect-ratio A6's
Post by: Flyguy on January 31, 2019, 06:49:37 PM
How about bringing your models to Kibbie this year? Don Slusarczyk (Cat 2 record holder) and I will be there along with Andrew Tagliafico and maybe a few other A-6 fliers.

That sounds like fun, but I'd have to make a box to carry the planes on a flight, which I've been thinking about but I'm not sure I'm at that point yet. I have thought about maybe Kent state, another Cat 2 site (like Teaneck, but higher) that's only a 7 hour something drive, have to see if anyone else here is interested in going. The tempting part about that one is it's hard not to think that if the A6 does almost 7 1/2 min with a strict 32 ft. limitation (and so-so rubber), like last week, then maybe it can get up around the 8 min range with an extra 10' of climbing space like at Kent!


Title: Re: High aspect-ratio A6's
Post by: Olbill on January 31, 2019, 07:58:13 PM
I'll be at Kent also. I haven't done as well at Kent as at Rantoul which is a good bit lower. I'm not sure why that is. For awhile I had the Cat 2 record set at Kent; then I broke it at Rantoul and then Don broke mine at Rantoul. I would expect Don to be over 8 minutes at Kent.

Part of my problem is that I can't steer so the model has to do its thing without my help. The lights at Kent are really bad about snagging models so I usually try to do safe flights there. My winning flight last year probably hit 10 times but still was only about 7 1/2 minutes.

I don't know if you do Facebook. Nick Aikman had an interesting answer to someone who was suggesting that some bad blocks of balsa that he recently got could be used for A6's. He posted a picture of your model and said something to the effect that good wood was just as important in a high quality A6 as in any other kind of model.


Title: Re: High aspect-ratio A6's
Post by: Olbill on January 31, 2019, 08:02:51 PM

We're on the same track, I got Leo's pitch block from Mike a few weeks back and have made two props with it so far, talked with Mike about it a little. All my area is in front of the blade, picture below, you can see that the blades have a lot of curvature. The block is 23p, then I set the blades rotated up to 28p and compared that to a 28p prop and I thought it was good.


I've never been successful running pitch that high. Maybe there's something magic about Leo's prop that makes it perform at higher pitch.

My new prop had a setback today when I couldn't find a good set of old prop spars. Tomorrow I'm going to have to taper a piece of wood and try to remember how to make F1L prop spars.


Title: Re: High aspect-ratio A6's
Post by: Flyguy on January 31, 2019, 08:14:53 PM
I'll be at Kent also. I haven't done as well at Kent as at Rantoul which is a good bit lower. I'm not sure why that is. For awhile I had the Cat 2 record set at Kent; then I broke it at Rantoul and then Don broke mine at Rantoul. I would expect Don to be over 8 minutes at Kent.

Part of my problem is that I can't steer so the model has to do its thing without my help. The lights at Kent are really bad about snagging models so I usually try to do safe flights there. My winning flight last year probably hit 10 times but still was only about 7 1/2 minutes.

I don't know if you do Facebook. Nick Aikman had an interesting answer to someone who was suggesting that some bad blocks of balsa that he recently got could be used for A6's. He posted a picture of your model and said something to the effect that good wood was just as important in a high quality A6 as in any other kind of model.

Cool, let me see if I can get there. Kent lights sound the same as Teaneck - real killers and you're gone if you hit them, that's why I stay below 32'. Steering isn't a problem since I don't do that either, but floor space is pretty tight at Teaneck so I make fairly tight circles; looks like there's more floor space at Kent.

No I don't do Facebook, damnit, that's neat about Nick, yes I'm using his balsa for the A6's (that's probably why some of them were underweight)! Hey does that mean that I get ahead on the queue if I put in another balsa order?  ;)



Title: Re: High aspect-ratio A6's
Post by: Flyguy on January 31, 2019, 09:30:52 PM

We're on the same track, I got Leo's pitch block from Mike a few weeks back and have made two props with it so far, talked with Mike about it a little. All my area is in front of the blade, picture below, you can see that the blades have a lot of curvature. The block is 23p, then I set the blades rotated up to 28p and compared that to a 28p prop and I thought it was good.


I've never been successful running pitch that high. Maybe there's something magic about Leo's prop that makes it perform at higher pitch.

My new prop had a setback today when I couldn't find a good set of old prop spars. Tomorrow I'm going to have to taper a piece of wood and try to remember how to make F1L prop spars.

Yes that's what I thought as well - it climbed higher at a lower torque, so I thought wow the increased curvature helps since the 28 p 'Leo' version was better than the other 28 p I had, although the 28 pitch still seemed to be a little too high. So the next Leo prop I made was 26 p and I had high hopes for that one, but it was surprisingly a bust, however I think the real problem in that case was that the spar for that prop was too flexible, the high curvature probably emphasized that problem, so the verdict is out, I'll make another one.




Title: Re: High aspect-ratio A6's
Post by: Olbill on February 02, 2019, 06:30:11 PM
Sorry to be off topic again - but to finish the F1L prop info I flew my new Leo style prop today at 24p and 22p. It got better times at each reduction in pitch but generally horrible times. Best was 7:54 at St. Lukes where I've done 14 in the past. Then I removed all the blade area behind the spar on one of my new flaring props and set it to 22p. I . This did 7:51. It would have been more but I had to relaunch after a wall hit. I used the same motor for all 7 of my flights with the last 3 or 4 being close to max winds.

Both of my new stabs are garbage. Will have to try again on the stabs to get under 100mg without warps.

Edited


Title: Re: High aspect-ratio A6's
Post by: Flyguy on February 02, 2019, 07:30:45 PM
Sorry to be off topic again - but to finish the F1L prop info I flew my new Leo style prop today at 26p, 24p and 22p. It got better times at each reduction in pitch but generally horrible times. Best was 7:54 at St. Lukes where I've done 14 in the past. Then I removed all the blade area behind the spar on one of my new flaring props and set it to 22p. I . This did 7:51. It would have been more but I had to relaunch after a wall hit. I used the same motor for all 7 of my flights with the last 3 or 4 being close to max winds.

Both of my new stabs are garbage. Will have to try again on the stabs to get under 100mg without warps.

That's OK on the off topic, should have put 'with a little F1L' in the title (can't edit titles right?), this is very interesting info. That was quick for tests! Sounds overall like your experience was similar to mine. Another problem is that you might need slightly heavier rubber for the Leo prop, seems like all that curvature increases the drag, but I'm not sure based on my own tests because -

-here's what happened with my first test a few weeks back. I had a 15" prop with a 24p blade set to 28, did some flights with that, then did some flights with a Leo blade of 23 set to 28. Had to wind first prop to high torque of .30 and got 12:50, height of 32' no touch, rpm of 92 (the required high torque is why I think that 28p is too much and I've gone down to 26). Next flight was with Leo prop, same rubber but wound to much lower torque of 0.20. Surprise was that it did 12:31, 32' no touch, rpm of 86. That's why I had high hopes with the Leo 26 the following week, but it had problems, though again I think that was a spar problem.

I made a new 27p prop, picture below, with the difference that the spar is now in front of the blade, we'll see how that does. I'm also going to give the Leo blade another shot, you can see in the photo the Leo block and the first Leo blade drying on the pitch block, 25 p this time. Wish I had more time to test all these props! Thanks again Bill for the info, I might go down to 22 on the Leo based on what you said.


Title: Re: High aspect-ratio A6's
Post by: Olbill on February 02, 2019, 08:12:56 PM
I just formed my blades with the tip 7 1/2" from the left edge of the block. I'm not sure how you would form the blades at a different pitch. Move them on the form? I actually didn't ask Mike what the pitch of the block is.

Today's motor was 1.4g x 18". It's pretty ridiculous for an 8 minute flight but at 13 or 14 minutes it's in the ballpark.

I was back to twisting the MS before launch in order to get an initial turn. I forgot on the last flight and hit the opposite wall. (launch torque .23 in-oz). West Baden, Kent and Kibbie will be easier but if the model doesn't wake up soon it won't be making the trips.


Title: Re: High aspect-ratio A6's
Post by: Flyguy on February 02, 2019, 08:51:02 PM
You form the blades the usual way at whatever the pitch is, the Leo block is 23 p, so you just form 23 p blades. However, when setting the blades on the prop spar, you rotate them up to a higher pitch. So instead of setting them at the usual angle for 23 p, which is 42.5 degrees at 4 inches, I set them at a higher angle. Leo mentions increasing the angle by 7 degrees, but 7.5 degrees will give you the same angle (50 degrees) at 4" as for a 30p prop. I was wondering about this myself and made the graph below, which helps to understand it. The Y axis shows the prop angle and the X axis shows the distance from the center in inches. The solid curve shows the blade angles for a 30 pitch prop. The dotted curve shows a 23 pitch prop where the angle of the blade was rotated up by 7.5 degrees at 4 inches, which gives 50 degrees at 4 inches, same as a 30 p prop (I did mine at 28p). First, the plot shows that having a lower pitch means that the angles vary more, the line is more 'curvy'. Second, compared to the straight 30p prop, the 23 prop 'rotated up' to 30 p has higher angles towards the middle and also a little towards the tip. So, 'rotating up' in essence adds a little 'wash-in' at the center and tips.

I was wondering about that because I know that F1D people have added wash-out to the tips, not wash-in. You can kind of do that by 'rotating down' - e.g., form the blade on a 28 p block and lower the angle to that of 26 p at 4 inches, that's what I did, that's the best one so far but I'm still working on it.

Holy cow, 1.4 gram at 18" that's huge! that encourages me not to be scared of trying some higher rubber weights, right now my motors for the 28 p props are 1.3 g at 20" and that seems heavy, my 13+min flight was on a 1.2 g motor. I have a long way to go on F1L because I just started flying it this season, whereas I had last year with A6 to make lots of mistakes and learn something!




Title: Re: High aspect-ratio A6's
Post by: Olbill on February 02, 2019, 10:53:37 PM
I guess I misunderstood what you were saying about what pitch the blades were formed at. Anyway, my models have a really hard time launching at higher torques. I guess I need to build a copy of Leo's model and give up on mine.

Fun fact about Leo unless he's changed recently - he uses 1g of rubber on his F1L. I think it's some sort of religious belief. I used to try to convince him to use more but getting beat sometimes changes my viewpoints.

The reason (in my opinion) for washing out the tips on VP prop blades is so when they are at extremely high pitch the tips will still give some thrust. For my F1M the prop blades at the root at launch are pretty much perpendicular to the direction of rotation. Most of the prop is stalled but still has enough thrust to keep the model in the air.


Title: Re: High aspect-ratio A6's
Post by: Flyguy on February 02, 2019, 11:20:25 PM
So far I've been OK at the higher torques, it chugs around at a near stall for a bit until a little torque burns off and then takes off. I see I spaced out above and gave my A6 motor sizes, forgot we were talking about F1L! The F1L sizes I've been using are 15" at 1.3g for 28 p and at 1.2 g for 26p, though I'm still in the early stages on this. You're 18" motor is pretty long!

Fun fact about Leo unless he's changed recently - he uses 1g of rubber on his F1L. I think it's some sort of religious belief. I used to try to convince him to use more but getting beat sometimes changes my viewpoints.

Yes that's damn light! I was using a 1 g motor when I was using a 14" prop with a 28 pitch, but went heavier for the 15" prop, also 28 p. But Leo's prop is symmetrical and mine has all the area in front of the blade, so that's another reason why I think I need heavier rubber, like at least 1.2g. I've been looking at both the 'going slightly heavier' and 'going slightly lighter' routes but I don't see any clear winners - nice example is that I have two flights both exactly 12:50 one with a 1.3 g motor and 28 p prop and one with a 1.2 g motor and a 26 p prop, and so? indoor is difficult!

The reason (in my opinion) for washing out the tips on VP prop blades is so when they are at extremely high pitch the tips will still give some thrust. For my F1M the prop blades at the root at launch are pretty much perpendicular to the direction of rotation. Most of the prop is stalled but still has enough thrust to keep the model in the air.

Yes agreed and that makes perfect sense, pretty much the same reason you use washout in the tips of a wing. But I don't know, you can convince yourself of anything if you argue long enough, I was thinking for example that, for Leo's prop, maybe the higher angle near the hub slows down the prop but the relatively lower pitch in the middle of the blade keeps it flying? (a variation on the washout argument). In any case I thought I knew something about props but these days I'm thinking I'm lost in the woods! I need to get in more flying time so I can try these things and see what happens, frustrating to wait a whole week to only be able to get a few precious hours!



Title: Re: High aspect-ratio A6's
Post by: Flyguy on February 08, 2019, 12:05:27 PM
I need to get in more flying time so I can try these things and see what happens, frustrating to wait a whole week to only be able to get a few precious hours!

Speaking of frustrating, there was an accident this week and the bus was delayed for over an hour, so I barely had time to run in, get a few flights, and race out (I have to get back by 1). Did set a new high time for my F1L of 13:42, but it only went up 28 ft., which leaves 5 feet to spare, would have been nice to get in another flight with a little higher torque! in any case it's looking good, the 26p prop seems to be good, though as usual I have some others to test, will report back on that later.

Getting back to A6's, below is a photo of my flying buddy Tom Juell's high aspect ratio A6. Beautiful work (as usual), came in close to target weight. He's since built another wing that's lighter and I think it's now around 1.19 g. He had some problems with it turning the wrong way for a few sessions, I think due to the tips, but he's since fixed it and also has another wing version with some polyhedral. Flew nice this week and did a respectable 5:30.



Title: Re: High aspect-ratio A6's
Post by: Flyguy on February 14, 2019, 09:35:28 PM
Just a quick note on how I'm doing A6 motors these days, not saying it's the best or only way, just saying this is how I do it. My bias was that, back in my heydays of indoor flying in the 60-70's, I never used O-rings for either my ministicks or EZB's, didn't need them, so that's my bias. So I was initially doing that with A6 as well, however I had some cases (with maybe only 200 winds left) where the motor slipped off the front hook (I've never had that problem with the rear), so I started using O-rings. However, I found that just using an O-ring alone for the front doesn't solve this problem, you have to use an O-ring and a sleeve. Eventually I started thinking why even bother with the O-ring, just use the sleeve, and that has worked really really nice, no problems at all. For the 'sleeves' I've used 1/16" heat shrink tubing and slightly larger sip straws, I like the heat-shrink tubing the best. I can just tie all the motors and then slip on the sleeves, I leave them back a bit on the motor, first pic is motors lubed and ready to go. Then I wind the motor, attach it to the hook, and slide the sleeve up against and slightly over the hook (the sip straws go up more since they are larger), second pic shows fully wound 20" motor (on a 6" stick!) with sleeve ready to go. I've been doing this on my F1L motors as well, keeps the rubber nice and centered and so far I've never had any problems.


Title: Re: High aspect-ratio A6's
Post by: Olbill on February 14, 2019, 10:11:26 PM
i guess I'm more fumble fingered than most but I'd never get the motor hooked up without o-rings.


Title: Re: High aspect-ratio A6's
Post by: Flyguy on February 14, 2019, 10:22:01 PM
I kind of was the opposite on this - the pennyplane size O-rings are easy to get on, but the small f1d ones I have were a real pain in the neck with fully wound motors, difficult to get on, at least for me. I thought it was easier to just let out a few winds and hook on, since that's what I'm used to doing anyway. The other thing I like is that you have to put on the O-ring when you tie up the motor, but not with the sleeve approach, you can add it later (with a little wire puller). But of course you can also leave on the O-ring and do the same thing with the sleeve. Given that I'm admittedly not an O-ring person, I'm glad the sleeve-only thing seems to be working!


Title: Re: High aspect-ratio A6's
Post by: Olbill on February 15, 2019, 01:19:55 AM
I'm sure I've posted this before. Now I use cocktail straws for sleeves instead of the red polyimide sleeve. The only place I could get the polyimide was from Ray Harlan. He would give me a few short scraps of it when I saw him at contests.


Title: Re: High aspect-ratio A6's
Post by: Flyguy on February 15, 2019, 12:11:52 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.


Title: Re: High aspect-ratio A6's
Post by: Olbill 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.


Title: Re: High aspect-ratio A6's
Post by: raggedflyer 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.


Title: Re: High aspect-ratio A6's
Post by: Flyguy 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!


Title: Re: High aspect-ratio A6's
Post by: Flyguy 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


Title: Re: High aspect-ratio A6's
Post by: Olbill on April 26, 2019, 02:42:06 PM
Nice work and nice flights!


Title: Re: High aspect-ratio A6's
Post by: Flyguy 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!




Title: Re: High aspect-ratio A6's
Post by: Flyguy 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.


Title: Re: High aspect-ratio A6's
Post by: Flyguy 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!