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Fri Jun 06, 2008 8:04 pm PostPost subject:
Mr.Entropy
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Well, the close-door buttons in my office building work. The problem I have with them is that the symbol for "close doors" looks like doors that are open, while the symbol for "open doors" looks more like doors that are closed.

A related point of interest: What exacty do the floor displays show you? In my office, the number changes to "n" at precisely the moment when you can no longer press a button to make the elevator stop at foor n. When the elevator is moving quickly, this is long before you actually get to the nth floor.
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Fri Jun 06, 2008 8:33 pm PostPost subject:
alsetalokin
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Errmm...I think the point of the article had more to do with logical fallacies, specifically the "post hoc, ergo propter hoc" one, as well as other pitfalls into which the scientific thinker might fall...

But one thing I have noticed in my travels: Elevator maintenance companies are almost always located in single-story buildings...
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Fri Jun 06, 2008 9:33 pm PostPost subject:
Mr.Entropy
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Yes, I know, but I have a strange unrelated interest in the complexities of elevator control software.
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Fri Jun 06, 2008 10:20 pm PostPost subject:
alsetalokin
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Software?
Elevators are controlled by software???
You mean, people willingly lock themselves into a tiny metal box that is then hurtled many hundreds of meters skyward, or earthward, at ridiculous v and dv/dt, and the damn things are controlled by software??
No wonder I prefer climbing stairs. Or staying on the ground.
http://www.youtube.com/watch?v=0wp-Dbb2CO4&feature=related
1:24-2:14
Crying or Very sad
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Sat Jun 07, 2008 2:56 am PostPost subject:
Harvey
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I can totally relate to that. When first learning the Advance Flight Model of the Su-25T it would take enormous (3-5 seconds) quanities of time to mentally acknowledge that the behaviour you were countering was in fact the auto controls rather than turbulence. Because of the airfoil delays the autopilot would always overcorrect and end up in a rollover. This was expecially problematic when flying autopilot and dropping a major ordinance from just one wing.

I'm also reminded of a friend who's flown choppers for years. He was called in to help diagnose an apparent problem with the blackhawk during autorotation. The setup as called out in the flight manual would pitch the nose up nearly 45. Every pilot that ran the simulation did exactly what the real pilot did. Dolphined it 3 times and impacted nose pitched 40+ down. On re-reading the procedure in the manual he asked if he could try that again and they let him. This time, instead of pushing the nose down during the inherent up pitch he let it ride. The craft hung tail low and autogyro'd the wings up to a substantial speed while bleeding of airspeed and decending at a moderately quick pace. About 50 feet above the ground the natural dynamics of the craft leveled out and the wing speed was fast enough it landed the last 50 feet with a velvet touch. He said its counter intuitive to be looking at the stars while doing a controlled crash into the ground - but thats what that bird calls for.

When ever I think of elevator buttons I can't help but laugh at George Wallace's stupid tax. He says anytime you see someone press a button already lit, charge them a buck stupid tax. If they pay the dollar, charge them another five. Mr. Green

I've know for years that the door close button is disabled on most elevators. Interestingly, some even seem to ignore the door open button which leads people to triggering the fail safe on the doors instead. What would happen if that switch failed to work? Shocked
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Sat Jun 07, 2008 3:29 am PostPost subject:
Harvey
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[quote"Yadaraf"] Question Question Question
alsetalokin wrote:

Errmm...I think the point of the article had more to do with logical fallacies, specifically the "post hoc, ergo propter hoc" one, as well as other pitfalls into which the scientific thinker might fall...


In other words, any strange occurances observed next friday will have nothing to do with previous occurances that happened on the 13th. Mr. Green

http://www.steorn.com/forum/comments.php?DiscussionID=59025&Focus=2208933#Item_35 Shocked


Last edited by Harvey on Sat Jun 07, 2008 8:43 am; edited 1 time in total
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Sat Jun 07, 2008 7:10 am PostPost subject:
Yadaraf
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Harvey wrote:

Errmm...I think the point of the article had more to do with logical fallacies, specifically the "post hoc, ergo propter hoc" one, as well as other pitfalls into which the scientific thinker might fall...


In other words, any strange occurances observed next friday will have nothing to do with previous occurances that happened on the 13th. Mr. Green

http://www.steorn.com/forum/comments.php?DiscussionID=59025&Focus=2208933#Item_35 Shocked[/quote]
Harvey,

That is kind of spooky ...

In the meantime, speaking of logical fallacies ...


Three students check into a hotel and pay $195 for one room, thus, spending $65 each. The desk attendant was told by the manager that he made a mistake, and that the room cost only $170, so he had to refund $25 to the three students. The attendant figured that the students couldn't divide the $25 into three equal parts, so he -- the crooked attendant -- kept $13 for himself and gave $12 to them to divide three ways. The students were happy because the room now cost them $195-$12 = $183, and each would only have to spend $61, thus saving $4 each. Now, if the students spend $183 for the room and the crooked attendant took $13 from them, this amounts to $13 + $183 = $196, and not the original $195. What's the deal with the extra dollar?

EDIT: modifed statement

Cheers Smile
Yada ...
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Sat Jun 07, 2008 8:49 am PostPost subject:
Harvey
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LOL, must be inflation. When I was young the room was 30 dollars on special for 25. The bell hop couldn't divide the five evenly so he pocketed 2 and refunded 3. Since each of the students originally paid 10 and got back 1, they each paid 9 dollars for the room. If you add the 2 dollars the bell hop kept you get 29 dollars. Where'd the other dollar go? Wink

Edit: PS, Al wrote that, not us Wink I fixed my quote.

The answer is 42. (HGTTG)

(and this number 1.452380952380952380952380952381)

Oh...and 3 Very Happy


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Sat Jun 07, 2008 8:51 am PostPost subject:
billgates
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Yadaraf wrote:
The room actually costs $13 + $183 = $196, and not the original $195. What's the deal with the extra dollar?


The room actually costs 170+13 to students (those 13 dollars were stealed by the attendant), the original room costs 170+13+12 (12 were refunded to students by the attendant).

What's the problem? Wink

btw where's the whipmag thread? Rolling Eyes
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Sat Jun 07, 2008 9:01 am PostPost subject:
Harvey
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Geeze Bill, that was no fun Rolling Eyes
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Sat Jun 07, 2008 9:09 am PostPost subject:
Harvey
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Quote:

btw where's the whipmag thread?


Here?
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Sat Jun 07, 2008 4:52 pm PostPost subject:
alsetalokin
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Sometimes that silly manual is right, after all.
My helicopter experience is R/C only, but I'm a high-time glider guider and taildragger driver; I've been over 32,000 MSL in the Sierra lee wave in one of these and I used to give acro demos in one of these, at a gliderport in the Mojave, where there were frequent strong crosswinds on interfacing with the ground. In a sailplane the normal technique in crosswinds is to touchdown in a slip; the upwind wing can almost be rolling on the ground and the pilot tries to keep the wing low so the wind doesn't get under it. When we took delivery of the Lark, everybody who flew it wound up weathervaning and groundlooping into the wind on landing, and some takeoffs were even aborted. I took a look at the poorly translated manual, and sure enough, the description of crosswind landings read like a misprint, so most of our pilots ignored it and did what they were used to, which didn't work. The flight manual says to execute crosswind landings wings level, and then bank away from the wind as the glider slows during the rollout. This technique would be disastrous in most gliders at our airport; on a good wave day crosswind components could easily exceed 30 knots. But I tried it in the Lark--rollout straight as an arrow and no tendency to weathervane or groundloop. The huge vertical fin required a bank in the opposite direction to keep the aircraft from weathervaning.
"Fully aerobatic" according to the manual, I would give acro demo rides during which I would take passengers through mild loops and barrel rolls and spins, but one day I wanted to see exactly what it was capable of, so I stuffed the line boy into the rear seat as ballast, towed up, and tried to roll it on tow...that didn't work, but after release, I did three continuous aileron rolls, and as we passed thru inverted on the third roll, the canopy popped open!! I managed to grab the rail with one hand while popping the speed brakes with the other and completing the now rather dishy roll with my knees on the stick...I couldn't get the line boy to ride with me any more after that...can't imagine why not, we didn't break anything, and all the sand and dirt and loose hardware got blown out of the cockpit, so he didn't have to clean it...
That ship could do a really neat vertical reversement, ponderoulsy wallowing thru the accelerated stall, standing motionless on its tail for a looonngg half-second, then falling off into the opposite turn...and it is really something to see a glider that big do a full snap roll...especially from inside!!
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Sat Jun 07, 2008 5:06 pm PostPost subject:
Yadaraf
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billgates wrote:
Yadaraf wrote:
The room actually costs $13 + $183 = $196, and not the original $195. What's the deal with the extra dollar?


The room actually costs 170+13 to students (those 13 dollars were stealed by the attendant), the original room costs 170+13+12 (12 were refunded to students by the attendant).

What's the problem? Wink

btw where's the whipmag thread? Rolling Eyes

billgates,

We were talking about holes in logic and also the duality of AGW and GW, when I recalled the duality of the hotel problem and $195 vs $196. Note that I could have stated the problem better by asking "how much did the students spend" instead of what the room costs.

Rework the problem, but have the crook steal only $1 instead of $13. The point is that when there is little difference between two observations (as with $12 vs $13) some of us can fall into traps of illogic. IMHO one way to shed light on the nature of AGW and GW might be to focus on what makes these two phenomeon different, rather than what makes them similar.

Cheers Smile
Yada ..
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Sat Jun 07, 2008 5:57 pm PostPost subject:
Harvey
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alsetalokin wrote:

...That ship could do a really neat vertical reversement, ponderoulsy wallowing thru the accelerated stall, standing motionless on its tail for a looonngg half-second, then falling off into the opposite turn...


We had a guy in LOMAC that could do that with a Mig-29 - he would open the canopy at the top and get it closed back up before the tail slide started. When ever I tried that I always lost the canopy. Primarily because it would always hammerhead on me.

FL30 Shocked Two questions: Hypoxia and Temperature inversion
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Sat Jun 07, 2008 6:55 pm PostPost subject:
alsetalokin
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"FL30 Shocked Two questions: Hypoxia and Temperature inversion"

Diluter-demand system in the aircraft and a 5-minute bailout bottle on the 'chute harness,
and
Damnnnnn collllddddddddd---polyprop longjohns, USAF cold-weather flight suit, electric socks, gloves, balaclava, etc.

(you forgot to mention ATC clearance to go above 18,000 MSL--obtained from Edwards ARTCC on an as-needed basis--the "wave window" it's called)
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Sat Jun 07, 2008 8:46 pm PostPost subject:
Harvey
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Awesome.

Funny, I never pictured a glider having a Mode-C transponder but I guess to ride the wave its necessary. Mr. Green
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Sat Jun 07, 2008 9:36 pm PostPost subject:
alsetalokin
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Nowadays pretty much so. Back then (mid 80's) you could get the controllers at EAFB to clear an altitude block, as long as they could paint you as a raw target. In the wave, your groundspeeds are typically really really low, like near zero sometimes, unless you are going crosscountry, in which case you won't be wasting time climbing to ridiculous altitudes anyway...so as long as you stayed in the "window" with a block clearance, and they could paint you, you were OK.
I did get "intercepted" once, just at the floor of the PCA with no clearance (well, maybe a few hundred feet into it)...I was watching the sunset thru the Tehachapi Pass, when an F4 came mushing by, flaps down, lights on, and as I cleared for the split-s in the other direction, I saw his wingman, 7 oclock high and half a mile, ready to shoot me down...They were just kidding, though; in those days we had a lot of fun, between the glider guiders, the parachute school, the test pilots at NWC China Lake, Edwards AFB, Fort Irwin tank-busters screwing around in Warthogs and OV-10s, the civilian operations at Mojave (Rutan and others). The famous skydiving short, "Proof", was shot there in those days--I'm the actual pilot of the stripped-out Skyhawk that was used in that movie (which also made it into the minor Major Motion Picture "Fandango")---my 15 minutes of fame, although I didn't actually get any credit for it...
It's a miracle I survived, come to think of it...
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Sat Jun 07, 2008 11:46 pm PostPost subject:
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hehe, I can relate to the Phantom full flaps mushing by - one of my favorite exercises in the LOMAC F-15 was to try and get it below 98knts level flight. Very Happy

Idea Gotta watch the movie now Smile

I wonder what it is that binds flying, electronics, music and art in so many through time. It's a special thread I think, that weaves through the likes of Da Vinci, Galileo and even Roger Waters. Sometimes we have a strong urge to fly but no where to fly to. Creativity.

Cool

EDIT: Wow, watched the movie Shocked Thats some hairy flying down the runway - and that ground buzz Exclamation Exclamation nice recovery. I'd never qualify for stunt work - my spare tire is in the way of the saftey chute Sad
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Sun Jun 08, 2008 6:41 am PostPost subject:
alsetalokin
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Heh...I used to wear a Security 150 thinpack, I doubt if I could buckle the harness now...
The low-level looks good, but my favorite part is the split-s. They asked me to "peel off dramatically"...so I did. I think the cameraman almost fell out of the little Grumman trainer they were shooting from.
That 172 was a rental! The guys rented it for a week from an FBO in southern CA, flew it up to the desert, stripped out the interior and painted it with that psychedelic paint job--tempera paint mixed with dishsoap--at the end of the shoot, they hosed it off, stripped out the Jimi Hendrix posters and the fuzzy dice, slapped the interior back into it and flew it home. Just an ordinary cross country rental...I bet the owners don't know to this day what that poor old Skyhawk has been through...
Mr. Green
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Sun Jun 08, 2008 7:32 am PostPost subject:
Harvey
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LOL! I loved rollout, very fluid. And I loved the seven independent landings at the end.

Well, as long as it wasn't good 'ol 2285 Echo - I'd fall out lauughing if it was the same one I trained in Smile. The last time I talked to Larry he said they retired her for general flights and are just using her for instrument training now. If it is the same frame its been inverted a few times over the years. Some students have problems with unusual attitudes Wink

Yep, I'm afraid in my current condition I would either not have full rudder control or wouldn't be able to clear the yoke for TO rotation even with a thinpack. I'd have to lose 100 pounds to get back to my premarital weight. Sad (prolly should start working on that b4 its 2 l8 )

Cheers on the 15 minutes - its always good to enjoy your work Smile


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Mon Jun 09, 2008 9:14 pm PostPost subject:
Yadaraf
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hmmmm ...

I wonder if Al buys stuff from Canadian Scientific.

.. like N35 magnets: http://www.canadascientific.com/navigation/detail.asp?MySessionID=161-596595440&id=N35.250.500

Cheers Smile
Yada ..
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Mon Jun 09, 2008 10:20 pm PostPost subject:
alsetalokin
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The lab has on occasion made a purchase from them, but not recently, and I don't remember what we bought--probably glassware.
Toronto Surplus is where we buy a lot of our vintage electronic test equipment, and we have another supplier that we call "Uncle Sid" who comes up with optics and a lot of other very strange stuff, but my rotor magnets came from Active Surplus in Toronto.
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Mon Jun 09, 2008 11:55 pm PostPost subject:
overconfident
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I was thinking of ordering some of these N38s from SuperMagnetMan:
http://www.supermagnetman.net/product_info.php?cPath=30&products_id=115
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Tue Jun 10, 2008 12:31 am PostPost subject:
Yadaraf
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overconfident wrote:
I was thinking of ordering some of these N38s from SuperMagnetMan:
http://www.supermagnetman.net/product_info.php?cPath=30&products_id=115

OC,

I just posted about surplus N35's from K&J. They're 9/16" instead of 1/2", but should be interesting to try. The 12% extended length might have an interesting affect on the exhibited phenomena. (Here's the post redux.)

.. N35 surplus: http://www.kjmagnetics.com/proddetail.asp?prod=ZD49

Cheers Smile
Yada ..
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Tue Jun 10, 2008 12:32 am PostPost subject:
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Hi All, I just got 10 of those a few days ago, they seem mesureably weaker than
the N42s that I have from KJ Magnetics Very Happy
I wonder how well a digital pocket scale would work to mesure relative magnet strength? Sit it on a steel plate?
Great another thing to buy for this project Laughing
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it seems a shame, the walrus said, to play them such a trick
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Tue Jun 10, 2008 12:40 am PostPost subject:
Yadaraf
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Gent wrote:
Hi All, I just got 10 of those a few days ago, they seem mesureably weaker than
the N42s that I have from KJ Magnetics Very Happy
I wonder how well a digital pocket scale would work to mesure relative magnet strength? Sit it on a steel plate?
Great another thing to buy for this project Laughing

gent,

IMHO, whatever you do, don't set it on a steel plate. Below are some notes that I have.

B (flux density): This is the measurement (in Gauss or Tesla) you get when you use a gaussmeter at the surface of a magnet. The reading is completely dependant on the distance from the surface, the shape of the magnet, the exact location measured, the thickness of the probe and of the magnet's plating. Steel behind a magnet will increase the measured 'B' significantly. Not a very good way to compare magnets, since B varies so much depending on measurement techniques.

Br (residual flux density): The maximum flux a magnet can produce, measured only in a closed magnetic circuit. Our figures for each magnet are provided to us by the magnet manufacturer. They are a good way to compare magnet strength...but keep in mind that a magnet in a closed magnetic circuit is not doing any good for anything except test measurements.

B-H Curve: Also called a "hysteresis loop," this graph shows how a magnetic material performs as it is brought to saturation, demagnetized, saturated in the opposite direction, then demagnetized again by an external field. The second quadrant of the graph is the most important in actual use--the point where the curve crosses the B axis is Br, and the point where it crosses the H axis is Hc (see below). The product of Br and Hc is BHmax. If we have these measurements available, they are provided to us by the magnet manufacturer--very complicated and expensive equipment is needed to plot a B-H curve.

Magnet Quality (BHmax): The quality of magnetic materials is best stated by the Maximum Energy Product (BHmax), measured in MegaGauss Oersted (MGOe). This is because the size and shape of a magnet and the material behind it (such as iron) have a large effect on the measured field strength at the surface, as does the exact location at which it measured. All of our Nickel-plated NdFeB magnets are grade N35 (BHmax=35 MGOe) and all of our Gold-plated NdFeB magnets are grade N45 (BHmax=45 MGOe). This gives about a 5% difference in strength, and a 150% difference in cost...it is wise to balance your magnet strength needs by cost too. Other magnets are measured the same way -- a grade 8 ferrite magnet (grade CCool has BHmax=8 MGOe.

Coercivity (Hc): This measures a magnet's resistance to demagnetization. It is the external magnetic field strength required to magnetize, de-magnetize or re-magnetize a material, also measured in Gauss or Tesla.

EDIT: ..Q: When you say you got "10 of those" are you referring to the 9/16" surplus N35s?

Cheers Smile
Yada ..
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Tue Jun 10, 2008 12:47 am PostPost subject:
Gent
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Hi all, Thanks for the info Wink
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it seems a shame, the walrus said, to play them such a trick
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Tue Jun 10, 2008 1:43 am PostPost subject:
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Yadaraf wrote:

... All of our Nickel-plated NdFeB magnets are grade N35 (BHmax=35 MGOe) and all of our Gold-plated NdFeB magnets are grade N45 (BHmax=45 MGOe) ...


I thought our NdFeB magnets were N42's Mr. Green
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Tue Jun 10, 2008 2:21 am PostPost subject:
Yadaraf
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Harvey wrote:
Yadaraf wrote:

... All of our Nickel-plated NdFeB magnets are grade N35 (BHmax=35 MGOe) and all of our Gold-plated NdFeB magnets are grade N45 (BHmax=45 MGOe) ...


I thought our NdFeB magnets were N42's Mr. Green

Harvey,

I believe Al said on Dec 27th that he used N35 generic. However, later he wasn't certain, and so performed a repel test from which he measured a separation of 30.5 mm. Because this distance is in between N35 (28.5 mm) and N42 (34 mm), as reported by another investigator, it begs the question:

... Is Al using N38s?

If we could place "known" N35 magnets in Al's rotor, we'd have the answer to our question. Because we cannot, however, we have to try every magnet grade between N35 and N42. Some magnet vendors have a minumium order of $50 and others are unbelievably expensive. Thus, I've ordered some surplus N35's for testing. I think OC will be ordering N38's. Lastly, I need to measure Al's rotor magnets -- via pixel counting, of course -- to see if they are in fact 0.500." I'll do that tonight. I'm headed out for run right now.

Cheers Smile
Yada ..
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Tue Jun 10, 2008 5:47 am PostPost subject:
Harvey
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LOL, you are no doubt correct there. Smile

I found it humorous that the quoted note made it look like "All of our Nickel-plated NdFeB magnets are" a particular grade Mr. Green

No worries. Wink

ummm, I think (grade CCool should be ( grade C8 ) Smile

Cheers
Cool
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