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Old Nov 11, 2012, 12:14 PM
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Terry Rigden's Avatar
UK, Bedworth
Joined Apr 2004
2,753 Posts
Thanks for the advice guys. How do I go about dynamic balancing ? I'm hoping for a quiet vibration free installation so I can get video under power without the jello effect.

I'm considering using a folding prop to help with the glide but setting on up as a pusher does not look pretty any one got experience with the improvement on the glide vs the poorer performance under power with a folder ?

Regards

Terry
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Old Nov 11, 2012, 01:10 PM
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NightRunner417's Avatar
USA, FL, Fort Myers
Joined Nov 2010
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Set your plane up with a full pack with a battery alarm on it so you can fool around with it freely and not have to worry about taking too long. Make up some kind of a secure "bench" affair to hold the plane steady, because you're going to be going anywhere from barely spinning the prop to going all the way to WOT and back again. I've done this mostly by just holding the plane down during opening the throttle, to placing dumbbell weights along the sides and a heavy box against the nose. Whatever holds it still SAFELY is what you want. You're going to be spinning that prop at high RPM, and buddy they can hurt ya.

I'd probably do it something like this: Take all hardware off the motor, connect the power to the plane, activate your TX, and throttle up smoothly from zero to WOT, listening to the motor and watching the shaft. An ungeared outrunner should be very low noise and sound very clean and whiney with little or no rasp or buzzing. If you see any vibration, and it may be very slight, start there by using a permanent marker to jusssst barely touch the spinning bell housing or motor shaft. Stop the motor and have a look. If your mark is uniform around the shaft or housing, then you're ok there and you can move on. If not, if it's heavy to JUST one side, then wipe it off with alcohol and a cotton ball and test it again. You want a repeatable test for this - a mark that is always in the same spot, thus showing an imbalance. If you can't get it to keep showing up, then stop and move on. Otherwise, weight the housing on the THIN side of the ink mark, with a tiny bit of cellophane tape. Keep repeating the test this way, very patiently, till the mark is coming out even, or reasonably even. Save "perfect" for the propeller adjustments.

Now, put your adapter on and if you have a nut for it, screw it down tight so you can see the adapter spin WITHOUT the prop. You just want to see if you've got a bad adapter, one with a bend in the stud. If you turn one up, you can use the marker technique and VERY careful tap-hammering on the adapter to try to bend it straight. Don't sweat it if it's not working out - it's ridiculously picky work and may not be possible to get it right.

The propeller is THE MOST contributing factor by a long shot, most of the time. Plastic props are generally molded like abject crap and even the APCs are always bloody WRONG. Some of the cheap HobbyKing stuff can be surprisingly on target, or absolutely terrible, as can any of the makes I've worked with (APC and EMP).

First, as I said before, make absolutely sure that your prop fits your adapter snugly before you even tighten it down. The "precision insert" is the key to this, usually. If it's loose at all, you're going to have endless balance issues, so pick the insert that is the tightest, and bore it out slightly if you have to in order to get it to fit. Now, take it off the adapter, put it on a balancer, and do the balancing by adding tape wherever needed. Once you've done that, tighten the prop onto the adapter, on the motor, watch your fingers, and fire up the throttle CAREFULLY so you don't have an accident. Ramp it up slowly and watch for a vibration. If you catch one coming on, then VERY CAREFULLY take advantage and mark the cone, nut, or tip portion of the adapter by touching the marker tip to the SIDE of it while the prop is spinning and vibrating. Cut the throttle and have a look. What will result is a mark that shows you exactly what angle the balance is out in. Now, you have a handy guide to where to add weight to - to the exact OPPOSITE direction of the mark. If you for instance see your mark at 3 o'clock on the side of the adapter nut, then you need to add weight to the prop at 9 o'clock, see?

If that means adding weight to a blade, then lucky you! Simply add tape, bits at a time and SMOOTHLY over the lighter blade of the prop, and keep repeating the test, erasing your old ink marks and making new to show the results of your efforts.

If the angle of weighting is between blades, then you've got a hub centering problem that will require weighting the hub itself. Again, weight to the OPPOSITE angle of the ink mark. I do this by carefully rubbing a tiny drop of CA on the side of the propeller hub, and then tacking down a tiny tab of regular note or typing paper. I keep doing this until my ink marks start coming up in line with the blade tips when I run the test. Then I turn my attention toward weighting the lighter blade, and generally, it's done and over pretty quickly and I'm finished.

If you're having success, you'll actually HEAR it in the motor system. It will start to sound less and less buzzy, and more and more "sweet"... like the high pitched whine of a jet engine, sort of. When it's in good balance, you'll be amazed at the clean sound of it and you'll never forget it.

You may end up having to compromise if you have a bad resonant vibration, meaning one that shows up dramatically worse at a certain RPM range. You may be able to tone it down, but not stop it, and that's really coming down to how stiff and unyielding your mount and foam are. You may be able to reinforce and stop it. I wasn't able to on my old EZ, but then too I didn't try very hard because I didn't intend to keep the plane anyways.

Two things to note:

1) You can also do this by placing a bright light behind the motor and prop from your point of view and watching for vibration, then experimenting with tape placement just basically from gut instinct, repeating the observations until you get it right. I used to do it that way till I had the marker epiphany.

2) Lots of people put all kinds of attention into making vibration dampening mountings for their jello-prone cameras. This is a bad solution to the problem and only covers it up, while the unbalanced motor/prop system is continually vibration-damaging the whole plane. Only resort to efforts to damp the camera itself if you simply CAN'T get rid of the actual source of vibration.

Edit:Phoo... now THAT is a long post!

Rick NR417
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Old Nov 11, 2012, 05:58 PM
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Terry Rigden's Avatar
UK, Bedworth
Joined Apr 2004
2,753 Posts
Nick

Thanks for the detailed instructions which I have printed out ready for a balancing session in the morning. I'll let you know how it goes

Regards

Terry
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Old Nov 11, 2012, 08:24 PM
Fly Like A Thing Posessed!
NightRunner417's Avatar
USA, FL, Fort Myers
Joined Nov 2010
1,777 Posts
Terry,

You're welcome... You inspired me actually to finally take a look at mine, following my own instructions. As it happens, I have a bent rotor-mount prop adapter - apparently damaged in my last crash. I may continue trying to bend it back but I went ahead and ordered two more from HeadsUpRC anyway, just to be better prepared. I canceled some of the vibration anyway by lining up the prop blades to match the angle of the bend and then taping the opposing blade. It's a dirty hack but it reduced it to the point I shouldn't even be able to see jello at all now in the HD recordings. It'll do till I get a replacement or fix this one up better.

Rick NR417
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Old Nov 12, 2012, 10:11 AM
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Terry Rigden's Avatar
UK, Bedworth
Joined Apr 2004
2,753 Posts
Fixed !

Gents thanks for all the help and advice on my vibration problem.

I tried to source an aluminium mount but they are hard to get over here so I cut out the cracked foaqm and put in a couple of ply braces from the motor mount down to the thicker part of the fuselage. Then I jammed Depron into the gaps and sanded it to shape. (see pictures)

Then I set about tackling the vibration at source, following Nick's instructions I set up a test fixture and set about balancing things.

The motor was pretty good but the original collet I was using was slightly too small and wasnt going fully onto the shaft. So I swapped it out for the right one. Then I checked the prop fit on the shaft and it was slightly loose. So changed to another collet with a larger shaft and carefully reamed the prop to suit. Then I checked the washer and found that running off centre too so I left it off. I then balanced the prop, it wasnt far out and I prefer to sand down the heavy blade after having had tape partially come off in the past.

Finally fire it up on the test rig and lo and behold its much quieter and vibration is much reduced. No visible flexing in the motor nacelle I couldn't get any consistency in the marks on the case and getting that close to a prop at 15K rpm is scary so I've left it at that. But since fixing the problem I've got a good 300 rpm extra .

RESULT !http://static.rcgroups.com/forums/im...es/biggrin.gif

The new motor/ esc combination is quite a bit lighter but even with the addition of a 15g flight stabiliser I have saved 38 grams on the AUW so now its just 570g ready to go. Add in the extra thrust from the prop going round 3000 rpm faster I'm hoping for a reasonable rate of climb. And if thats not enough I have room for a bigger prop .

The current set up is as follows

Battery 1800mAh 2S lipo
ESC Funfly 18A
Motor Turnigy D2826-6 2200Kv 50gr
Prop 6x3
Static measurements
Current 14.75A
Voltage 7.3V
RPM 15300

I also tried a 7x4 but the current was over 20 A so I shut down, also a 7x3 folder but I have worried about the blade retention system.

So if it ever stops raining I will test it with the 6x3.

Regards

Terry
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Old Nov 12, 2012, 12:01 PM
Fly Like A Thing Posessed!
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USA, FL, Fort Myers
Joined Nov 2010
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Quote:
Originally Posted by Terry Rigden View Post
Gents thanks for all the help and advice on my vibration problem.

Finally fire it up on the test rig and lo and behold its much quieter and vibration is much reduced. No visible flexing in the motor nacelle I couldn't get any consistency in the marks on the case and getting that close to a prop at 15K rpm is scary so I've left it at that. But since fixing the problem I've got a good 300 rpm extra.

So if it ever stops raining I will test it with the 6x3.

Regards

Terry
Glad it worked out for ya in the end. I was thinking about it this morning when I again flew with my powered paraglider friends, but despite my bent adapter I only show just a little jello on takeoff (very high power WOT burst) and the rest of the HD recording was flat as glass other than the very turbulent conditions at the field. It'll work for the time being, but to reduce vibrational damage and other such effects I just really want to get it taken care of eventually.

Had a FUN time out there. The PPG people were fewer this time - only two of the pros present, and two of the girls who are still learning - plus the conditions kept them mostly occupied with training the girls on how to manipulate their wings on the ground in the fairly strong wind. Thus, I had the field mostly to myself and I used it HARD for proximity practice. Came away with some great video but I tapped the HD keycam's battery out before I was done for the day so I missed a lot too. By the third pack, I was flying like a maniac about a foot or two above ground/weeds/earth moving machinery/etc, fun times despite the crazy turbulence. I noted a ground speed differential against vs. with the wind of almost 30mph at times - she was pretty rowdy out there. The plane flew GREAT and no crashing or weird behavior, and this time I pulled off two very nice landings in front of the audience. :-)

Working up a vid but it's going to be a short-ish music vid type so it's going to be some processing work.

Rick NR417
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Old Nov 12, 2012, 03:45 PM
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Terry Rigden's Avatar
UK, Bedworth
Joined Apr 2004
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Rick

Glad you had a good days flying , none for me it P****ed down with rain all day, Wednesday is looking hopeful. I'll also be testing the Orange RX flight stabiliser, two new things at once might not be the best idea but I'll start off with the gains turned right down. I'm hoping that the stabiliser will iron out the bumps so videos taken in windy weather wont make my audience feel travel sick.

Regards

Terry
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Old Nov 12, 2012, 04:07 PM
Fly Like A Thing Posessed!
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USA, FL, Fort Myers
Joined Nov 2010
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Terry,

I think you'll do fine... Like you said just start out with low gain, get some decent accident-insurance altitude, and then try cranking it up. I don't think that fooling with a prop and fooling with a stabilizer in the same day is at all crazy an idea... I've done much worse.

Speaking of which, I did get to do some better testing with my gyros today in the crazy turbulent conditions. I have a roll gyro on the ailerons and a pitch gyro on the elevator, with gain for both on receiver channel 6 for on the fly adjusting. I found that if I cut the gain entirely, she was very loose and wobbly in a slow, drifty kind of way. If I turned them up too high, then she seemed tight but very prone to oscillation on each gust-hit. If I turned them down to about midway, she was as "just right" as I could hope for, with a slight oscillation on each shove but still easy enough to control that I kept getting better at ground scraping even as the winds got more agressive over the course of the morning. Never had any problems with weird stall behavior, though I probably was never going that slow to start with. I overshot one landing in a BIG way, and ended up floating down into the wind nice and soft... and the other landings were maybe not perfectly spot on but I did almost land at the one woman's feet, lol. Pretty good. Knowing what I do now, and given my flying style, I'd probably never be happy without at least some kind of basic stabilization. If nothing else, it does seem to "raise the bar" with respect to what kind of weather one can fly in, and when you live in a windy place, that's a nice thing. :-)

I'm also daydreaming a LOT lately about getting a CC3D controller board for my quad so I can take advantage of MUCH improved flight stability there as well.

Looking forward to seeing how that Orange RX works for you!

Rick NR417
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Old Nov 13, 2012, 05:54 PM
Fly Like A Thing Posessed!
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USA, FL, Fort Myers
Joined Nov 2010
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Yesterday morning at "C Field". Windy as hell, crazy turbulent. Didn't stop me, lol.

11-12-12: Low-n-Fast At "C Field" (4 min 31 sec)



Rick NR417
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Old Nov 14, 2012, 12:23 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
Joined Nov 2008
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Quote:
Originally Posted by NightRunner417 View Post
Yesterday morning at "C Field". Windy as hell, crazy turbulent. Didn't stop me....
'Course, Crazy Horst would have flown under the arm of the digger.............

Really cool video, Rick. Thoroughly enjoyed it!
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Old Nov 14, 2012, 08:54 AM
Circa:1946
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Rick

Nice video.
I guess you know, but try not to land or crash too
close to one of those borrow pits.

If a Gator is near, your plane will be gone in a blur.

Regards
Jimmy
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Old Nov 14, 2012, 09:46 AM
Why so serious?
2500GENE's Avatar
United States, FL, Cape Coral
Joined Dec 2007
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Quote:
Originally Posted by Colonel Blink View Post
'Course, Crazy Horst would have flown under the arm of the digger.............

Really cool video, Rick. Thoroughly enjoyed it!
Forget the digger, I was waiting for hit to try through the pipe.
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Old Nov 14, 2012, 09:49 AM
Why so serious?
2500GENE's Avatar
United States, FL, Cape Coral
Joined Dec 2007
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Quote:
Originally Posted by Riverratss View Post
Rick

Nice video.
I guess you know, but try not to land or crash too
close to one of those borrow pits.

If a Gator is near your plane will be gone in a blur.

Regards
Jimmy
Yeah, and stop scaring the Palms on fly-bys...
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Old Nov 14, 2012, 10:44 AM
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UK, Bedworth
Joined Apr 2004
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Brusless conversion test flight

Rick

Nice video Looks like an "interesting" place to fly.

Anyway I test flew my Mk1 Estar with its new brushless motor and the flight stabiliser.

Well teh motor is a great sucsess the flight stabiliser I've not made up my mind yet, at least it did no harm.

I cant measure the rate of climb but it is now adequate, it takes about 12-15 seconds at partial throttle to reach as high as I want to go whereas with the standard motor it took at least 30 seconds at full chat to get there. This means I will be able to fly from smaller more confined fields.

My set up is as follows

Motor Turnigy D2828-6
ESC Funfly 18
Battery gensace 2S 1800
Prop 6x3
AUW 570grams

On the ground this set up pulled about 13-14amps and spun the prop at about 15000 rpm drawing about 100W

As for the Orange Rx flight stabiliser it seems to slow servo response which isnt a big issue with this model but I didnt see a great improvement in stability either. I started with the gains set fairly low then turned them up slightly for each flight. To test I would deliberately stall the model then see how it recovered hands off. Before I fitted the stabiliser it would stall twice more before returning to stable flight. And that what happened the first two flights. then I turned up the gain a little more and it took 3 cycles to return to stable flight.

I also did some tight turns without compensating with up elevator the model would dive in all cases. The on board video I took doesn't seem any smoother than before I fitted the stabiliser but it was a calm day

I'll need to do more tests but so far I'm unimpressed by the flight stabiliser

Terry
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Old Nov 14, 2012, 11:33 AM
Fly Like A Thing Posessed!
NightRunner417's Avatar
USA, FL, Fort Myers
Joined Nov 2010
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Quote:
Originally Posted by Colonel Blink View Post
'Course, Crazy Horst would have flown under the arm of the digger.............

Really cool video, Rick. Thoroughly enjoyed it!
Quote:
Originally Posted by 2500GENE View Post
Forget the digger, I was waiting for hit to try through the pipe.
Quote:
Originally Posted by 2500GENE View Post
Yeah, and stop scaring the Palms on fly-bys...
Quote:
Originally Posted by Riverratss View Post
Rick

Nice video.
I guess you know, but try not to land or crash too
close to one of those borrow pits.

If a Gator is near, your plane will be gone in a blur.

Regards
Jimmy
Thanks, you guys. Lol Gene, that's not a frightened palm... that's a Rasta Palm yelling, "Eyyy mon don git that flyan ting in me gangaaaa!"
Also... Lol one of my friends on Facebook also told me he was waiting for me to try flying through the pipes, lol. Maybe next time. Did y'all notice that there was apparently someone INSIDE one of the pipes? That had to be an interesting experience... X-D

Jimmy, lol it's funny you should say. When I first got there, all four of my paraglider friends were standing around talking and looking at the lake to the north side. There was a little one peeking up above the water, apparently watching the blackbirds that were all over the shore. I laughed and told them that he's probably waiting for the BIGGER birds to arrive on the scene. Just was a little guy, probably 3 - 4' long.

Quote:
Originally Posted by Terry Rigden View Post
Rick

Nice video Looks like an "interesting" place to fly.
The on board video I took doesn't seem any smoother than before I fitted the stabiliser but it was a calm day

I'll need to do more tests but so far I'm unimpressed by the flight stabiliser

Terry
Hi Terry, glad your motor and prop combo worked out well. About that stabilizer - you probably won't see much effect on a calm day because unless it's some other model, it's just a 3 axis gyro. My experience is that calm days don't really do anything for gyros on a plane, and vice versa. They're going to do basically nothing of course when there is input happening, and then if there's nothing to push the plane around, they'll sit there still doing pretty much nothing. It's when it gets turbulent that they really start to react.

I did some testing to see just what effect they actually have, on the morning I shot that video. If I turn the gain down to nothing, then the plane feels really loose and rolly... It's still very responsive, of course, but the gusts caused her to sway around quite a lot. If I then turned it up to maximum, it felt wild and jittery... oscillating to the gusting and over correcting. I found that the best setting was midway, which gave a good compromise of sane amounts of counter correction but still gave that "ok that's far enough" kind of gust-induced motion blocking. The video is still a bit wobbly, but I feel that without an expensive stabilizer that also has accellerometers, sky/ground sensing, etc, that's just something I'll have to put up with. I'm not going there because I may soon have a Zephyr to build up and that's going to cost me some to get it airborne.

Try it again but in some real wind... I'm talking like 10-15mph plus some turbulence. I think you'll find that when you set the gain right, you can handle her a WHOLE lot better in the rough stuff than without. It may in fact lift your weather
limitations a bit. I know I feel safer flying in rougher weather since adding my gyros and my videos are almost always more stable because it's almost always windy here. They're for "girls" that want more rigid control when the wind is strong enough to push the pilot around on the ground and still come away with usable video. :-)

BTW absolute YES on the interesting factor of my flying area. It was interesting enough back when I used that area to learn on my first RC plane, a Skyartec Skyfun. Now that it's open again and has become a construction zone, it's definitely #1 on my list of "interesting places". :-)

Rick NR417
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