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Old Apr 15, 2010, 09:06 PM
Dave North
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USA, CA, San Jose
Joined Apr 2004
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Termination Error?

I'm fairly sure I made a termination error on my last 36 delta half parallel. I just redid it with the full transit method and got Rm = 055, Kv = 806 and Io = 1.38. The first time I did this wind using the adjacent tooth transit, I got Rm = 055, Kv = 895, Io = 3.19 using the same test equipment.

Something was wrong with that first one.

The Full Parallel results are still unknown and useless. My assumption of some termination error on the 42Y was probably incorrect. When I was unwinding it, the wire on one of the teeth was cleanly fractured. Cheap junk! So basically I was testing 11 teeth plus some unknown arc.

So, lots of turns, a decent motor, and no conclusive lessons learned except that when you put a bunch of wire on a big motor, it's easy for things to go wrong.


Dave
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Old Apr 16, 2010, 12:46 AM
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Originally Posted by jackerbes View Post
The SpaFFFnutz is a righteous flier for the DAT-750, mine is using a Great Planes Power Flow 10 x 4.5 slow fly prop.

Jack
Jack, sounds fun... a 96" spaffnutz. A pusher project would eliminate my worries about the shaft. Besides, I've been waiting for the opportunity to make full use of FFF's 48" dimension, and got a lot of FFF and full size servos collecting dust. Might finally find a good home for the enormous 4s4800 lipo my uncle gave me years ago.

I see you're using a123's.

Kev <- jealous of the a123's
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Old Apr 16, 2010, 12:59 AM
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Originally Posted by timocharis View Post
...the wire on one of the teeth was cleanly fractured. Cheap junk!

So, lots of turns, a decent motor, and no conclusive lessons learned except that when you put a bunch of wire on a big motor, it's easy for things to go wrong.


Dave
Dave, cheap wire? I bet you wish you used MD wire after that. DT750 are a joy to work with though, so I understand the attraction. Might get the more out of some other motors, but the $$$ and the sharp corners can be quite an obstacle.

Kev
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Old Apr 16, 2010, 07:23 AM
Jack
USA, ME, Ellsworth
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Originally Posted by Truglodite View Post
Jack, sounds fun... a 96" spaffnutz. A pusher project would eliminate my worries about the shaft. Besides, I've been waiting for the opportunity to make full use of FFF's 48" dimension, and got a lot of FFF and full size servos collecting dust. Might finally find a good home for the enormous 4s4800 lipo my uncle gave me years ago.
What a great idea! A twin engined SpaFFFnutz with two DAT-750's. The character or stiffness of the coro/FFF hybid is kind of interesting.

I made sure the wrapped around FFF in the KFm strips and the center filler panels were well bonded to the coro with full contact when I PU'ed them on byt not skimping on the prep work on the coro.

That gave a wing that had some flexibility in it but but none of the flex was localized at all. It just drew one smooth curve from tip to tip when I weighted the center and picked it up by the tips.

In flight, I never noticed that I was inducing any visible flexing or stresses that worried me. Even in the wildest maneuvers. The weak spots in that first build are the ones where I am adding the skewers to the coro at the prop slot in the build thread I've got going now. That build is a little stalled unfortunately as I'm nursing a bad knee and badly pre-occupied by my most recent addiction, a Blu Sail II glider.

I had some flutter in the elevons until I moved the servos out to put the horns almost in the center. If you buy a full 4' x 8' sheet of 4mm coro and do something similar to the SpaFFFnutz I think I see a real beautiful flier there with the KFm4 airfoils. And if you wanted to stagger the steps a little in a sort of KFm7 fashion it would give a wider line of stiffening on the coro/FFF joint at the steps.


Quote:
I see you're using a123's.
Yep, I got started with the 1100's and liked them and went to 2300's too. I really like the cells and seem to build things that work OK with them. I still use some LiPOs too but when a plane can handle the weight the A123's get the nod.

The 1100's are the more expensive A123's to get now but I got a good supply when they were cheap. The 2300 A123's are down around $7 a cell pretty reliably now. Here is eight brand new 2300's for $40 and they'll ship two of them for $10 so that is about $5.65 per cell delivered.

http://www.toolking.com/dewalt-dc928...n-nano-battery

The price there just dropped $10 in the last few days!

If you can add one "S" to any LiPO's you are using now and handle a weight of 28 to 32 grams per cell per 1000 mAh of capacity, A123 may be an option. They are tough, recharge fast, and long lived has been the bottom line for me.

Feel free to PM me if I can be of any help on the any of this.

Quote:
Kev <- jealous of the a123's
My prescription for a medication is acquisition.

Jack
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Old Apr 16, 2010, 09:54 AM
Dave North
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USA, CA, San Jose
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Originally Posted by Truglodite View Post
Dave, cheap wire? I bet you wish you used MD wire after that.
Yes and no. Yes in that it hasn't ever done anything like this in my experience. No in that it's a bit thicker than Consolidated and probably would not have fit with 42 turns. So I'm not sure it would have been possible. Though what the heck, maybe someday I'll try it.


Dave
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Old Apr 23, 2010, 03:21 AM
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Is anybody able to find these in stock?

I've been hunting, but I've not come across anything yet!
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Old Apr 23, 2010, 04:27 AM
Jack
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I bought a few about two weeks ago from R2Hobbies in Hong Kong:

http://www.r2hobbies.com/eng/proddet...=rcps81529_750

They were $10.32 each. They were polite, quick to reply to an email, and coherent in English. Had the motors in 10-12 days.

Jack
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Old Apr 23, 2010, 04:52 AM
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Unfortunately they seem to be out of stock now, I'll keep looking for an alternative
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Old Apr 23, 2010, 06:55 AM
Jack
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Email them and ask them about it, they were shown as out of stock when I found them listed there and I sent an email to them and asked when they would have them again. I got a reply within a day that they were back in stock. I ordered five of them and they filled the order and shipped immediately.

The shipping on five DAT-750's and a couple of other small items was about $17 or so the motors cost me about $13-$14 in the door. I was a little concerned about finding them and maybe their going out of production or something so I "stocked up" a little as this is a motor I will use quite a bit.

I have a thing about the rampant stupidity in the customer service department at Hobby King, they will not get any more of my business if I can find other dealers who do a better job. I seem to have better luck with the Hong Kong and Taiwan based dealers than I do with the guys on the mainland. I know many here love Hobby King and have never had a problem with them, that has not been my luck.

Jack
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Old Apr 23, 2010, 08:28 PM
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Originally Posted by jackerbes View Post
Email them and ask them about it, they were shown as out of stock when I found them listed there and I sent an email to them and asked when they would have them again. I got a reply within a day that they were back in stock. I ordered five of them and they filled the order and shipped immediately.

The shipping on five DAT-750's and a couple of other small items was about $17 or so the motors cost me about $13-$14 in the door. I was a little concerned about finding them and maybe their going out of production or something so I "stocked up" a little as this is a motor I will use quite a bit.

I have a thing about the rampant stupidity in the customer service department at Hobby King, they will not get any more of my business if I can find other dealers who do a better job. I seem to have better luck with the Hong Kong and Taiwan based dealers than I do with the guys on the mainland. I know many here love Hobby King and have never had a problem with them, that has not been my luck.

Jack
Thanks, sounds like good news. I've been perusing that website and I've found they've got some pretty competitive prices on some other things too!

I'll shoot them and email now.
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Old Apr 27, 2010, 02:59 AM
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Quote:
Originally Posted by jackerbes View Post
I have a thing about the rampant stupidity in the customer service department at Hobby King, they will not get any more of my business if I can find other dealers who do a better job. I seem to have better luck with the Hong Kong and Taiwan based dealers than I do with the guys on the mainland. I know many here love Hobby King and have never had a problem with them, that has not been my luck.

Jack
I've come to think of HK as the old stand by, but the past few months I have to agree they've been horrible in many ways. If popular items being constantly out of stock and delayed shipping isn't annoying enough, the "red whine" on the front page will do it. A special box to display weak excuses for lack of service and anecdotes about improvements they're making? I'd rather receive a rose in the mail. Really though, the poorly planned (or poorly managed?) "new warehouse" BS is getting old... I wish they'd jus' git 'er dun!

Kev
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Old Apr 28, 2010, 04:24 AM
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Originally Posted by Truglodite View Post
I've come to think of HK as the old stand by, but the past few months I have to agree they've been horrible in many ways. If popular items being constantly out of stock and delayed shipping isn't annoying enough, the "red whine" on the front page will do it. A special box to display weak excuses for lack of service and anecdotes about improvements they're making? I'd rather receive a rose in the mail. Really though, the poorly planned (or poorly managed?) "new warehouse" BS is getting old... I wish they'd jus' git 'er dun!

Kev
From our perspective in the supply chains, the world is changing. No longer are people reaching for their credit cards and buying because they can, they are buying sparingly and only when they must.

This means the economics of holding stock that may not shift that fast are biassed entirely towards only ordering what you know you can sell, and sell pretty sharpish.

To put it another way, the conflict is between poor delivery and service, and expensive pricing. Both absent are unlikely to make for a viable business model.

Its invidious. People ignore the stock position in favour of keen pricing when buying, and then complain about the service quality when the goods don't arrive yesterday.

If you don't quote cheap you don't get the deal: If you don't JIT the operation, you lose money.
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Old Apr 28, 2010, 06:12 AM
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V1 has hit the nail squarley on it's head with

" If you don't quote cheap you don't get the deal: If you don't JIT the operation, you lose money"

I have had good service from HK so far and whilst it is a nuisance having to wait for backordered parts, my experience is that they are fairly quick to re-stock.

On one occasion they even called up and asked if I wanted to drop one item from the order (a single prop as I recall) so that they could ship the rest to avoid a delay.

Their pricing is such that a small delay is well worth a few minor problems, and I have found that their packaging and shipping to be excellent, well tracked and reliable.

just my two 'penneth. Sparks
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Old Apr 28, 2010, 07:51 AM
5,200 Led Lighted Bike-Bob P.
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I just got a notification that the Hex DT-700 is back in stock. They may have the Hex DT70's also. I have a "Wish List" and they are now notifying me of items in my wish list when they come back in stock. Nice feature. By the way, I have had 28 orders with HK over the past few years and I never had a problem with them. It is about being patient. That is what works. I buy needed items that I need faster elsware.
Happy Flights
**Neons** Bob

Update: Just looked at stock and the 700's show 10+ motors. The 750's show BK Back
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Last edited by **neons**; Apr 28, 2010 at 11:52 AM. Reason: Update
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Old Apr 29, 2010, 08:45 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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One of the guys over on my SpaFFFnutz build thread is in the UK and was looking for one of these motor, he found them for sale on eBay from a Hong Kong seller. They are a little less than $15 shipped to the U.S.

The ones I got out of Hong Kong come in a black box, have a Turborix Brushless Motors label on them, and come with three 3.5mm bullet connectors (plugs and sockets) and shrink tube.

Jack
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