Kites & kiting

Turtle · September 10, 2013

Okay dokaly. Firstly, I may or may not actually complete a testable model. I have kiboshed before, and I will... kibosh... again. (Seinfeld; you either get these or you don't. ;) )

Nevertheless, it's still on like Donky Kong. :piratesword: Shall we make it a contest then? First one to build a working line monkey that covers 20ft of line forward and then reverse and stops? No kite needed there; just a clothes line will do.

There is a kite-specific design feature that is worth noting, which is the separating distance between leading & following end-pulleys. This separation damps twisting in the carriage, that is rotations around the vertical axis. Same reason for using a tube as I have been doing, rather than just an eye-bold to ride the line.

So I have the second end-pulley roughed out and together. I also cut the 2 main frame members from 1/2" X 1/2" doug-fir scraps from Matilda. Waste not, want not. :P I want to have the pulley stand proud of the frame in front & back so those high sides can do their work of guiding the line. In the photo the axles are 1/2" in from the ends.

I think next I need to experiment with one of the motors on a 9v battery as I have no idea of its RPM's. Neither do I know of any simple way to tell. How about y'all? Well, since I figure to use pulleys & belts the next thing to do is make a sheave to fit the motor. Then I can use the stand-in reel and drive it with a belt and get some idea of RPM.

:coffee_n_pc:

Turtle · September 10, 2013

All righty thens. New motor pulley/sheave/drum manufactured & installed. 1/4" sheet plastic of unknown kind. The effective diameter at the bottom of the grove is 5/8" . I found a Pulley and RPM calculator that may prove handy once I determine motor rpm. Well, if you're into that kind of sciency stuff, here it is. >> Pulley & RPM Calculator @ Culver Armature & Motor

:coffee_n_pc:

Turtle · September 10, 2013

A few theoretical calculations has me thinking a pulley train will be necessary. As I say I have seen this type of motor rated between 6,600 to 15000 rpm. As they are rated at 12v and I'm running at 9v I presume it will be slower. The motor runs steady and with good torque on the 9v battery. Steady running determined by ear, and torque assessed by trying to grab hold of the spinning pulley. :doh: As ususal, that's not the way for you to do it or you may end up like Little Monkey ***.. :rotfl:

I think for my setup the 3" pulley is as large as I should go because of space and wind, but I did calcs for 4" for comparison over a small range. Here's the scoop. :clue:

5/8" = 0.625"

@4000 rpm

3" = 833.33 rpm

4" = 625.00 rpm

@5000 rpm

3" = 1041.67 rpm

4" = 781.25 rpm

@6000 rpm

3" = 1250.00 rpm

4" = 937.50 rpm

@7000 rpm

3" = 1458.33 rpm

4" = 1093.75 rpm

:coffee_n_pc:

DFINITLYDISTRUBD · September 10, 2013

I think next I need to experiment with one of the motors on a 9v battery as I have no idea of its RPM's. Neither do I know of any simple way to tell. How about y'all?

Could mic it, determine its frequency, and compare to a known motor with the same number of armatures.

Turtle · September 10, 2013

Could mic it, determine its frequency, and compare to a known motor with the same number of armatures.

I'll get a vid with mics close. You can remix it! :lol: Problem here though is no known motors to compare. I think it's 5 on mine & I will count for sure. Still, I'm not certain that's a sure tell for rpm? Isn't rpm also a matter of wire diameter and number of windings on each armature?

Here's an e-bay listing & as you may see there is a wide range of rpm's in otherwise identical looking cases. >> e-bay 12 volt motors

Anyway, I can proceed without knowing the motor rpm since I know the max & min size of pulleys I want to use and the travel speed on the line that I want. Haven't done the calcs yet to see if I can get away with 2 'ranks' of step-down or if I will need a 3rd.

There is the problem of belts still. Prolly neoprene O-rings? Suggestions? For now I will be using rubber bands.

DFINITLYDISTRUBD · September 10, 2013

It all boils down to magnetic vibrations, and mechanical ones as well. Despite very similar engines an angle grinder has a very different motor sound than a drill.

The number of armatures determines the number of electrical field changes (I'd actually skip the mic and instead use a coil) three armatures at 1000 rpm has a different sound than five especially when looking only at the electrical noise generated. I'd wager on an osciloscope the electrical noise signature for the same RPM would look very different as well. @ 1000 RPM I'd expect the motors electrical noise to be in the 50hz range for three armatures, for five armatures in the neighborhood of 83hz.

Hrrrrrmmmmmm.....one could compare the sound to that of a tone generator set to a matching frequency and determine RPM fairly accuratlely......methinks.

Edited September 10, 2013 by DFINITLYDISTRUBD

Turtle · September 10, 2013

It all boils down to magnetic vibrations, and mechanical ones as well. Despite very similar engines an angle grinder has a very different motor sound than a drill.

The number of armatures determines the number of electrical field changes (I'd actually skip the mic and instead use a coil) three armatures at 1000 rpm has a different sound than five especially when looking only at the electrical noise generated. I'd wager on an osciloscope the electrical noise signature for the same RPM would look very different as well. @ 1000 RPM I'd expect the motors electrical noise to be in the 50hz range for three armatures, for five armatures in the neighborhood of 83hz.

Hrrrrrmmmmmm.....one could compare the sound to that of a tone generator set to a matching frequency and determine RPM fairly accuratlely......methinks.

Acknowledged all. :clue: Will get you the sound bite tomorrow. :cap:

Did some calcs. :smart: I earlier said 3mph, but when rock comes to roll that may be too fast. :dogwalk: Course this is all idealized and on a kite line the way gets steeper as you go.

Here's my notepad. Better check me. :read: :naughty: :kick:

1 mph = 1.46 ft/sec = 87 ft/min

1.5 mph = 2.2 ft/sec = 132 ft/min

2 mph = 2.9 ft/sec = 174 ft/min

2.5 mph = 3.6 ft/sec = 216 ft/min

2.5" drum [this is the final pulley that drives the line.]

2.5 * pi = 7.85" circumference

2 rpm = 15.7" = 1.3 fpm

3 rpm = 23.55" = 1.96 fpm

4 rpm = 31.4" = 2.61 fpm

5 rpm = 39.25" = 3.27 fpm

...

100 rpm = 785" = 65.4 fpm

120 rpm = 942" = 78.5 fpm

133 rpm = 87 fpm = 1 mph

Thoughts?

PS How bout I strap an Estes M engine on the back of this baby? : OMG: Whhhhooooooooosssshshshshshshhsh....... :doh:

Edited September 10, 2013 by Turtle

DFINITLYDISTRUBD · September 10, 2013

I think too fast would be determined by how much force the kite can sustain without coming down while the climber goes up...but further thinking finds me :doh:...um yeah, additional the force exerted by the climber will only matter during initial acceleration, after that ist all weight :doh:

I dunno, I'm sure you have the same thoughts regarding speed. You want it up the line reasonably quick so it will hopefully reach it's desired height before the wind changes it's mind, but at the same time really fast is fraught with technical issues and potential failures.

Slower there are the perils of good ol unpredictable wind and the carriage may never make it to it's destination before you find yourself racing to recover from a change in direction or velocity.

Faster requires less reduction and so less torque to unjam should the carriage bind on it's way up, slower has greater torque but could make a jamb worse just as easily as prevent it.

Faster allows for a smaller time window to get the kite aloft, the carriage up, and pics taken. Slower requires more time which may or may not be available and may prevent taking advantage of a little free time and good wind.

1 mph = 1.46 ft/sec = 87 ft/min1.5 mph = 2.2 ft/sec = 132 ft/min 2 mph = 2.9 ft/sec = 174 ft/min 2.5 mph = 3.6 ft/sec = 216 ft/min 2.5" drum [this is the final pulley that drives the line.] 2.5 * pi = 7.85" circumference 2 rpm = 15.7" = 1.3 fpm 3 rpm = 23.55" = 1.96 fpm 4 rpm = 31.4" = 2.61 fpm 5 rpm = 39.25" = 3.27 fpm ... 100 rpm = 785" = 65.4 fpm 120 rpm = 942" = 78.5 fpm 
133 rpm = 87 fpm = 1 mph

I'm assuming these numbers are line speed after reduction....

I'm thinking you will need two pulley reductions....unless you're using the gearmotor .

I'd recommend shooting for 3 m/ph. Not too fast, not too slow... off my head roughly 1000' feet of line in less than 5 minutes..still seems interminably long, but should be a reasonable and achievable goal...with at least a marginal degree of reliability. I think much faster will result in technical issues rearing their ugly heads with a good deal of frequency resulting in much aggravation for less reward.

DFINITLYDISTRUBD · September 10, 2013

You going to test the unit at close to vertical?...I figure ideally the carriage should be able to lift itself and it's payload, would be the easiest test to confirm it will reach it's destination once on the kite's line.

Turtle · September 10, 2013

snip...
I'm assuming these numbers are line speed after reduction....
I'm thinking you will need two pulley reductions....unless you're using the gearmotor .
I'd recommend shooting for 3 m/ph. Not too fast, not too slow... off my head roughly 1000' feet of line in less than 5 minutes..still seems interminably long, but should be a reasonable and achievable goal...with at least a marginal degree of reliability. I think much faster will result in technical issues rearing their ugly heads with a good deal of frequency resulting in much aggravation for less reward.

Yes; line-speed after reduction. What is this reward of which you speak? :rotfl:

You going to test the unit at close to vertical?...I figure ideally the carriage should be able to lift itself and it's payload, would be the easiest test to confirm it will reach it's destination once on the kite's line.

Will test vertical, horizontal, swinging line, jerking line, slacking line, etcetera. When the tough gets going, the going gets tough. :jab:

Here's vid of motor running on 9v with no load. :singer:

http://www.youtube.com/watch?v=YMoyu016yVw&feature=c4-overview&list=UUiDIgwwtUxDi7fxhELuBtxg

DFINITLYDISTRUBD · September 10, 2013

Judging by no load speed for 6 pole induction motors being close to the results for audio and rf created by a D/C motor I'ma run with it with the minor revision of using (hz X 60) divided by the number of armatures. for 3 I get 1340, which seems reasonable if that is a 12V motor running 9V, using the same math for 5 armatures yields 804 which seems way off. Assuming the resonance is the result of mechanical imbalance or that each rotation only produces 1 hz magnetic variation we skip division and get 4,020 rpm. Still looking for a proper formula...off to research D/C motor's...perhaps I can find a resource that specifies how the arms are powered per rotation.......Dangit it seemed simple enough......

Edit:

two different formulae are needed. one mechanical hz, one electrical hz.:doh: should have been obvious....seeing as the electrical noise of a motor is typically higher in frequency :doh:

Almost forgot for a brush type motor it appears only one arm is fully energized at a time. for odd number armatures, I'd expect two oppositely polarised armatures for even number armatures...still looking.

Edited September 10, 2013 by DFINITLYDISTRUBD

Turtle · September 10, 2013

I think too fast would be determined by how much force the kite can sustain without coming down while the climber goes up...but further thinking finds me :doh:...um yeah, additional the force exerted by the climber will only matter during initial acceleration, after that ist all weight :doh:

I dunno, I'm sure you have the same thoughts regarding speed. You want it up the line reasonably quick so it will hopefully reach it's desired height before the wind changes it's mind, but at the same time really fast is fraught with technical issues and potential failures.

Slower there are the perils of good ol unpredictable wind and the carriage may never make it to it's destination before you find yourself racing to recover from a change in direction or velocity.

Faster requires less reduction and so less torque to unjam should the carriage bind on it's way up, slower has greater torque but could make a jamb worse just as easily as prevent it.

Faster allows for a smaller time window to get the kite aloft, the carriage up, and pics taken. Slower requires more time which may or may not be available and may prevent taking advantage of a little free time and good wind.
...

Wanted to touch on these worries, for worries they be. :omg: Getting a machine to pull itself along a static string is one thing, and doing it on a dynamic kite line is quite another. I think the monkey needs -ultimately- an active control so it can be speeded up, slowed, stopped, reversed at the command of the flyer. Using my tube-followers I can tell you that the line & kite often need some time to re-stabilize to/with the changing line load. Not sure if radio or wire control will win out.

There is also the matter of wind-load on the monkey itself. Can/will the weight of an aerodynamic cover/body be justified by the turbulence it reduces? How the hell do i KNOW!? wHAT; AM i YOUR mOTHER? :rotfl:

I noticed in those e-bay adverts that some of these motors are actually rated at 18v, not that I necessarily shy away from using voltages above ratings. :lightning Anyway, if I use 2 9v batteries in series and add a rheostat I can vary the speed without changing the 'gearing'. :ideamaybenot: Can we say governor? :blink:

:piratesword: But I don't wanna be a pirate! ~JS

Turtle · September 10, 2013

Judging by no load speed for 6 pole induction motors being close to the results for audio and rf created by a D/C motor I'ma run with it with the minor revision of using (hz X 60) divided by the number of armatures. for 3 I get 1340, which seems reasonable if that is a 12V motor running 9V, using the same math for 5 armatures yields 804 which seems way off. Assuming the resonance is the result of mechanical imbalance or that each rotation only produces 1 hz magnetic variation we skip division and get 4,020 rpm. Still looking for a proper formula...off to research D/C motor's...perhaps I can find a resource that specifies how the arms are powered per rotation.......Dangit it seemed simple enough......

Edit:
two different formulae are needed. one mechanical hz, one electrical hz.:doh: should have been obvious:doh:

OK. Just checked and the motor has 3 armatures. :cap:

DFINITLYDISTRUBD · September 10, 2013

Well then that is good news, I'm confident that 1300-1400 or so rpm is reasonably accurate.

3 hz to one revolution, based on the models I've found so far, seems like it should right for ( 67 [hz] X 60 [seconds] ) / 3 [armatures] = 1340 [RPM].

still digging there's bound to be evidence of someone out there that has sorted the math out....after all it works for I/C engines ( [hz] X [time] ) / [cylinders] (cylinders divided by 2 for four stroke engines)

Example in reverse a single cylinder two stroke (1000 [rpm] ÷ 60 [seconds] ) ÷ 1 [cylinders] = 16.666666667 [hz]

Starting with a known approximate frequency and cylinder configuration (16×60) × 1 = 960 [rpm] of course divided by two if it were a four stroke.

What do you think mr turtle? Am I close enough? am i missing something?

Turtle · September 11, 2013

Well then that is good news, I'm confident that 1300-1400 or so rpm is reasonably accurate.
3 hz to one revolution, based on the models I've found so far, seems like it should right for ( 67 [hz] X 60 [seconds] ) / 3 [armatures] = 1340 [RPM].
still digging there's bound to be evidence of someone out there that has sorted the math out....after all it works for I/C engines ( [hz] X [time] ) / [cylinders] (cylinders divided by 2 for four stroke engines)
Example in reverse a single cylinder two stroke (1000 [rpm] ÷ 60 [seconds] ) ÷ 1 [cylinders] = 16.666666667 [hz]
Starting with a known approximate frequency and cylinder configuration (16×60) × 1 = 960 [rpm] of course divided by two if it were a four stroke.

What do you think mr turtle? Am I close enough? am i missing something?

I'll take you at your word. While I'm accustomed to listening to tools to determine cutting/operating speed, it's only in the sense of too slow, up-to-speed etcetera and not the actual rpm. I don't doubt for a minute that your skill is authentic considering your shop & musical experience. :thumbs_up

Time will tell as I manufacture & test the pulley train. Like my couple of box kites, this motor is 30 years old. I can see all manner of metal filings inside clinging to the magnetism and I can only imagine the bushings are worn as well. No worries as a good part of this is to use what I have on hand. Well, otherwise I would be going nowhere fast. :lol:

In the midst of a heat wave today and the next 3 if the forecasters have it right. Don't expect much productivity from me. :weather_hot: I would worry one of you could get ahead of me, but I think it unlikely anyone is trying. :jab:

Adieu! :coffee_n_pc:

DFINITLYDISTRUBD · September 11, 2013

LOl, just wasted several hours trying to set up an add for my truck on Fleabay...it needs to go, I need something efficient, capable of hauling wedding cakes regardless of weather, capable of hauling the kids and the grands, and most importantly fuel efficient. the only way I'm getting another vehicle is if I can get it gone....If it sells soon enough though I may skip 90% of the list and snap up a '66 mustang that has my eye, or a VW squareback that also has my attention, or maybe another bus if one turns up...The last on the list would be a winner for certain if I could find one for the right money and in reasonable decent serviceable condition.

One issue at a time.... right now I'm juggling two 1. I need a practical set of wheels, and 2. I need a job and C. I need those practical wheels as there's nothing local employment-wise and I'm not planning on riding lucky lucy in the snow this year...and would rather avoid riding to work in the rain...don't mind the wet but not being able to see sucks.

DFINITLYDISTRUBD · September 11, 2013

****ing idiots, yet another township meeting to try to block installing wind turbines on the hill. I'm surrounded by idiots. BTW I'm all for wind farms here. They mean jobs, tax revenue, hopefully cheaper power, and quite frankly I like think their neat, nifty, groovy, and downright cool.

There are a couple on a mountainside on the route down to my birthplace really really big ones...I always find my attention drawn to them...just too neat too ignore.

Back to the subject at hand:

I really hoped in all of your mathematical wizardry you would have either confirmed my simple formula or presented an alternative....oh well.

If that trike of yours had a speedo you could have driven the wheel noted the speed converted it to tire rpm based on tire circumference then calculated the reduction and got the answer for the motor under load. :P

No worries.

I've a feeling the speed of the device will be limited by the needed reduction to get the torque necessary for it to function and will either be ridiculously slow or right around the 3mph ideal.

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Kites & kiting

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