Rimfire motors - Page 2 - RC Groups
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Sep 09, 2007, 08:52 PM
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Dr Kiwi's Avatar
Quote:
Originally Posted by Diogenes2you
Plus ca change, c'est la meme chose, eh?

I agree! Just toss a coin! Or, go where your pocket will be happiest.

If you really are on a tight budget you can probably get an even cheaper HXT motor from UH which might or might not do the job just as well [but are you enough of a gambler?].
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Sep 09, 2007, 10:34 PM
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Which one will likely last longer?
Sep 10, 2007, 09:19 AM
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Reversed the Propshaft


OK, I decided to reverse the shaft in my Rimfire 28-30-950, so that the spring keeper and thrust washer would prevent the shaft from moving forward. So I did it and the motor is back in the model.

The only thing that I don't like about this fix is that there isn't anything holding the shaft in the stator now, except the magnetic field. I'd feel better about it if there was a positive lock, as there was in the original configuration. The keeper and thrust washer that are now at the rear of the motor performed this function before. When the motor is running, the thrust from the prop acts to keep things together but I still don't like it much. We'll just have to see how it works out as time goes by. I wonder if I've voided the warranty.

CR

P. S.: I forgot to mention that I had to move the cowl back a bit to clear the prop. This is because there's not as much shaft sticking out of the motor now. It was either move the cowl back or space the motor forward.
Last edited by Charley38; Sep 10, 2007 at 09:23 AM. Reason: Added text
Sep 10, 2007, 09:55 AM
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Ask Electrifly if the warranty is void, or take a look at the papers that came with it. It appears that the only free lunch is with the Axi, or is that not so, Dr.?

addition: it appears the worst that will happen is that you must pay 50% of the "then current list price" if you make a modification within two years (what happens after that?) that Electrifly determines to be "the cause" of "damage" ("This warranty does not cover damage caused by abuse, misuse, alteration or accident.")

put yourself in electrifly's shoes-this is an alteration, so if there is some damage to repair, you may wind up spending 50% more over the long term should you turn the shaft around.
Last edited by Diogenes2you; Sep 10, 2007 at 10:06 AM.
Sep 10, 2007, 10:01 AM
Registered User
Dr Kiwi's Avatar
Quote:
Originally Posted by Charley38
OK, I decided to reverse the shaft in my Rimfire 28-30-950, so that the spring keeper and thrust washer would prevent the shaft from moving forward. So I did it and the motor is back in the model.

The only thing that I don't like about this fix is that there isn't anything holding the shaft in the stator now, except the magnetic field. I'd feel better about it if there was a positive lock, as there was in the original configuration. The keeper and thrust washer that are now at the rear of the motor performed this function before. When the motor is running, the thrust from the prop acts to keep things together but I still don't like it much. We'll just have to see how it works out as time goes by. I wonder if I've voided the warranty.

CR

.
But unless you run the motor in reverse, where can the bell and shaft go? - with the prop on they can only go forward.
Sep 10, 2007, 10:04 AM
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Dr Kiwi's Avatar
Quote:
Originally Posted by Diogenes2you
Ask Electrifly if the warranty is void, or take a look at the papers that came with it. It appears that the only free lunch is with the Axi, or is that not so, Dr.?
I don't know the terms of Axi's warranties (nor Electrifly's). I do know that H-L will replace any Axi, outside the warranty period, for 50% of the new price. I have done that witth a 2212/34 which failed.
Sep 10, 2007, 10:12 AM
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Quote:
Originally Posted by Dr Kiwi
But unless you run the motor in reverse, where can the bell and shaft go? - with the prop on they can only go forward.
But won't that damage the model "if" it happens? And, if the alteration is made and damage occurs to the model, you pay 50% of "then" retail and get what?
Sep 10, 2007, 10:14 AM
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Quote:
Originally Posted by Dr Kiwi
I agree! Just toss a coin! Or, go where your pocket will be happiest.

If you really are on a tight budget you can probably get an even cheaper HXT motor from UH which might or might not do the job just as well [but are you enough of a gambler?].
No, I'd rather be certain up front rather than have other damage or the inconvenience of waiting for a replacement. It seems that for a novice like me the 50% would be better spent up front on a sure thing. This is what I meant by "free lunch" though I don't mean anything is free, just "more free" from worry or inconvenience, etc.
Sep 10, 2007, 12:11 PM
Registered User
Quote:
Originally Posted by Dr Kiwi
But unless you run the motor in reverse, where can the bell and shaft go? - with the prop on they can only go forward.
Unless there's a nose-over with the motor at low or zero RPM. Things like that are a fact of life in RC flying, no matter how good the pilot is, especially in the GP WWI fighters. This fix makes the motor more vulnerable to damage from that sort of thing. We'll see how it works out.

CR
Sep 10, 2007, 01:05 PM
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Fourdan's Avatar
Hi
My contribution
Starting from Phil results post#1:
---
The Rimfire 28-20-1000 (41g) and the Komodo KH2208-9 (1020Kv, 41g) seem close enough donít they?
9x5 GWS HD:
Rimfire: 10.9v, 8.40A, 91W, 7740rpm, 36.6mph, 597g, 21.02oz, 6.56g/W, 85rpm/W
Komodo: 10.9v, 10.25A, 111W, 8340rpm, 39.5mph, 719g, 25.32oz, 6.48g/W, 75rpm/W

---
I can deduce with the Badcock Prop calculator giving Pout(@prop)
Rimfire , GWS 9x5HD 7740 rpm Pin= 91.56 W Pout = 62.6 W Eff = 68.37%
Komodo GWS 9x5HD 8340 rpm Pin=111.73 W Pout = 78.4 W Eff = 70.17%
Conclusions (same voltage)
1) Komodo Kv is higher
2) Komodo Peakeff is slightly better, even at a higher current
Note that different software gives different Pout(@ prop)
9x5 GWS HD @ 7740 W
1) Badcock Pout = 62.6 W
2) D-Calc Pout = 58.4 W
3) Scorpion Calc Pout = 66.3 W
So I have selected Badcock in the middle range
I have to make other measurements on the GWS 9x5 to try to put the most probable coefficient Kpower on Scorpion Calc v2.27
Louis
Sep 10, 2007, 01:54 PM
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Dr Kiwi's Avatar
Quote:
Originally Posted by Charley38
Unless there's a nose-over with the motor at low or zero RPM. Things like that are a fact of life in RC flying, no matter how good the pilot is, especially in the GP WWI fighters. This fix makes the motor more vulnerable to damage from that sort of thing. We'll see how it works out.

CR
I'm having trouble seeing where the problem is - if you nose in, the adapter and prop are going to hit first, and maybe the shaft + bell moves back a mm or two until the back of the collet hits the mount plate. Unless the prop and adapter come off in flight, then you nose the bare shaft into the ground... then I suppose the shaft + bell could be pushed back 9mm until the tip of the shaft was flush with the mount...... even then, how is the motor getting damaged?
Sep 10, 2007, 02:50 PM
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Why not spend the 50% up front on a motor that need not be altered?

I guess my point is this-as I'm buying a motor, I think I'll buy one that does not need alteration, but, if I had one that does, I should expect to pay to have it repaired if my alteration causes the damage I want repaired.

I'm not saying this very well, but I think I'm better off buying a motor that does not have to be altered rather than risking the shaft problem and the fight over who altered or caused what and what it costs to repair, ship, etc.
Last edited by Diogenes2you; Sep 10, 2007 at 02:58 PM.
Sep 10, 2007, 07:27 PM
Balsa to the Wall
Chuck's Avatar
Quote:
Originally Posted by Diogenes2you
Why not spend the 50% up front on a motor that need not be altered?

I guess my point is this-as I'm buying a motor, I think I'll buy one that does not need alteration, but, if I had one that does, I should expect to pay to have it repaired if my alteration causes the damage I want repaired.

I'm not saying this very well, but I think I'm better off buying a motor that does not have to be altered rather than risking the shaft problem and the fight over who altered or caused what and what it costs to repair, ship, etc.
Sometimes you gets what you pays for. I don't personally know anyone who has had a problem with an AXI motor. But they are expensive, by the time you pay extra for the prop adapter and mount.

Chuck
Sep 10, 2007, 07:56 PM
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Quote:
Originally Posted by Chuck
Sometimes you gets what you pays for. I don't personally know anyone who has had a problem with an AXI motor. But they are expensive, by the time you pay extra for the prop adapter and mount.

Chuck
Kind of my point, and I agree-if you might wind up with paying for repairs because you alterned the $45 Rimfire, why not add 50% up front and buy the Axi? (Yes, I'm sure another few bucks are required but the point is the same-if you are buying, buy "RIGHT" but if you already have one that should be "altered," keep in mind it will cost you money (50% of the list price) if you need repairs, later.

I guess the sum of all this is all this hue and cry about a "fix" seems misplaced-spend the money on something that doesn't need to be "fixed" and which carries a full warranty because it doesn't need to be fixed. And, if you can get an Axi replacement after two years for 50%, gee, that's a no brainer in terms of a long term investment!
Last edited by Diogenes2you; Sep 11, 2007 at 09:53 AM.
Sep 11, 2007, 06:16 PM
Registered User
Quote:
Originally Posted by Dr Kiwi
I'm having trouble seeing where the problem is - if you nose in, the adapter and prop are going to hit first, and maybe the shaft + bell moves back a mm or two until the back of the collet hits the mount plate. Unless the prop and adapter come off in flight, then you nose the bare shaft into the ground... then I suppose the shaft + bell could be pushed back 9mm until the tip of the shaft was flush with the mount...... even then, how is the motor getting damaged?
What collet? There isn't enough shaft sticking out to use the collet and the prop adapter. The adapter won't hit the mount plate, it will go back all the way to the motor housing. It's apparent that you're ignorant of how the motor mounts in the GP WWI warbirds.

In any event, no matter how much you try to help salvage the Rimfire reputation, it's obvious that this motor has flaws. No one is going to buy one of these if they know about it. I certainly wouldn't; I just decided to try the fix rather than return the motor to Tower for a refund.

Enough,

CR


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