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Old Jul 25, 2014, 04:49 PM
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United States, MA, Webster
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Quote:
Originally Posted by Colonel Blink View Post
EZ2s are quieter than EZ1s....
I am no expert on this, but I think there is a logical progression on motor speed that has invoked quite a change in prop noise. The original EZ* had a "Cheapo Speed 400" brushed motor, which was a common power source for aircraft of this size / weight. As folks replaced them with brushless motors, they tended to use motors of around the same RPM .. usually around 2200 Kv.

As time has gone by, many have discovered that a lower Kv motor with a higher pitch prop will work as well or better. Certainly, as you reduce Kv., to say 1100, and thus the speed of the prop, the tip speed of the prop gets slowed down, resulting in a substantial reduction in prop noise.

Just my two cents ..

Russ
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Old Jul 26, 2014, 11:43 AM
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Martin7182's Avatar
Bussum, Netherlands
Joined Oct 2009
741 Posts
You're right Russ, but I think higher pitch is less efficient. I don't care that the EZ* makes some noise. You can't have it all. For FPV is is ideal because the from the nose you have a clear view.

Martin
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Old Jul 26, 2014, 09:19 PM
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United States, MA, Webster
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Originally Posted by Martin7182 View Post
You're right Russ, but I think higher pitch is less efficient. I don't care that the EZ* makes some noise. You can't have it all. For FPV is is ideal because the from the nose you have a clear view.

Martin
Hi, Martin:

Again, I am not a propeller engineer .. but many have found a "sweet spot" with lower motor / prop speed and slightly increased pitch .. also true for helicopters and quads. Some side-effects are lower vibration and quieter performance .. and occasionally more flight time !

Meanwhile .. YES .. the EZ*, with it's pusher power system is fabulous for AP / AV and FPV .. no doubt.

Russ
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Old Jul 29, 2014, 03:34 PM
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Terry Rigden's Avatar
UK, Bedworth
Joined Apr 2004
2,571 Posts
Getting some of it back

Just had a call from the farmer, he has found the motor and battery but the rest went up the bailer. I'm relieved the battery has been found not that it will be any good but it can now be disposed of properly and won't start a fire. I had visions of a bailer or barn going up in flames.
I'll go and fetch the remains Thursday who knows I might even get the servos if the centre section has survived. No mention of the camera but being small and black I didnt have much hope, pity there was probably good footage on the card.

Terry
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Old Jul 30, 2014, 06:22 AM
Circa:1946
Riverratss's Avatar
Joined Jun 2008
148 Posts
Terry

At least you have and end to the story!
Sorry for the loss.

Regards
Jimmy
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Old Jul 30, 2014, 11:06 AM
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United States, WV, Calhoun
Joined Nov 2004
509 Posts
Quote:
Originally Posted by Colonel Blink View Post
EZ2s are quieter than EZ1s....
Since I am using the same motor and prop on my EZ2 as I did on my EZ1 it makes the same amount of noise. And it sounds like a very large bee that is mad - noisy. The Mega 16/15/4 or 16/15/3 with a standard 6 x 4 or 6 x 3 prop makes for a sporty setup on either EZ.

You asked earlier about the throws on the EZ2. They are pretty extreme. But to get good rolls you need to keep the speed up.

I really like the EZ2.

Todd
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Old Jul 31, 2014, 10:58 AM
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UK, Bedworth
Joined Apr 2004
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Just got back from the 3 hr round trip to the farm for the remains of my E star I got the motor and prop, esc and the bit of the fusealge above the wing and the battery.
Now I was expecting to have to dump the battery but it looks undamaged and read 8.18 v with each cell at 4.09v. I slowly discharged it (@3C) to 3.85v / cell and it stayed in balance. I suspect it got disconnected in the crash but it has been rained on a few times in the two weeks since the crash plus lots of sun. . It doesnt look physically damaged , I suspect going down in tall crop dissipated the impact.

So I'm wondering whether to give it a recharge at the bottom of the garden and see how it reacts to that. Any ideas , warnings or other advice?

Terry
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Old Jul 31, 2014, 03:28 PM
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United States, MA, Webster
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Quote:
Originally Posted by Terry Rigden View Post
Just got back from the 3 hr round trip to the farm for the remains of my E star I got the motor and prop, esc and the bit of the fusealge above the wing and the battery.
Now I was expecting to have to dump the battery but it looks undamaged and read 8.18 v with each cell at 4.09v. I slowly discharged it (@3C) to 3.85v / cell and it stayed in balance. I suspect it got disconnected in the crash but it has been rained on a few times in the two weeks since the crash plus lots of sun. . It doesnt look physically damaged , I suspect going down in tall crop dissipated the impact.

So I'm wondering whether to give it a recharge at the bottom of the garden and see how it reacts to that. Any ideas , warnings or other advice?

Terry
ASSUMING there is no obvious damage to the pack, I would charge it back to 7.4 v, check the balance, then discharge back to 3.85 v/ cell, check for balance again. If all seems well, charge it full, in a safe place, and "give it a go", as you folks over in the UK seem to say.

My thoughts,

Russ
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Old Jul 31, 2014, 03:34 PM
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Terry Rigden's Avatar
UK, Bedworth
Joined Apr 2004
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Russ

I presume you meant charge to 8.4v, yes I'll give that a go and at just 1C charge rate. Not sure whether to watch it carefully or stay well away.

I'm leaving it at 3.85v/ cell for a while to see if it stays in balance.

Terry
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Old Jul 31, 2014, 04:18 PM
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United States, MA, Webster
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Quote:
Originally Posted by Terry Rigden View Post
Russ

I presume you meant charge to 8.4v, yes I'll give that a go and at just 1C charge rate. Not sure whether to watch it carefully or stay well away.

I'm leaving it at 3.85v/ cell for a while to see if it stays in balance.

Terry
Well, actually I meant to not charge it to capacity after the first discharge .. do it in two steps to monitor low and high voltage cell balance.

As you earlier stated, with a tall field, the pack probably didn't hit the ground at all .. it may have got to the ground as the harvester went by ?!? if the pack did get disconnected from the ESC, and there are no obvious slices / punctures / dents in the pack, and with the voltage measurements you made, the pack is probably O.K. The jury is out on the rain, though ..

Russ
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