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Old Aug 04, 2009, 08:26 PM
EDF Nut
carl rich's Avatar
Cincinnati
Joined Jan 2006
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Data
DS-51 tested and compared to Midi

DS-51 tested w/ Lehner 1950-11 motor, 1140Kv, 350g, 74mm long, 36mm diam.
Test used 9" long exhaust cone w/ exhaust diameter of 74mm +/_ 1mm. Just grabbed same cone had been using for recent Midi fan tests. Inlet ring is modified Midi ring to fit nicely.
Spin 75 ESC with Frequency and Timing each set to 8, 10s 3250mAh 40C ThunderPower LiPos heated to 90F. Resistance is so low on these new packs that heating may not make much difference.

Data collected at 4 times per second. Graph is mean of many readings and not usually the absolute peak current, rpm, etc, but very close.

Maximum readings are;
41.9V dropping to 38.08, 64.46A, 128.3 oz (8lbs 0.3oz) 2479W, 43,025 RPM,

Efflux with tube being held in the center by my trusty clamping post read 186mph. Could have been blocked a little by the center cone being dead ahead of it 5 inches or so. Retested and used my hand to move the tube around the opening to find max airspeed. Efflux 197mph.

For comparison... Similar watts from LiPos going to different motors / Midi fan from previous tests. Believe I have some other tests out there in the same ballpark but not enough time to search for them.

ARC 36-55-2.5, 1100kv motor 55mm long, 8.2 oz with connectors
11s 7700ma 105F,
45.98v - 41.3v, 60.3A, 121.2 oz T, 2517.5 W, 39,575 rpm, 950kv under load, 193mph eflux

ARC 36-75-1 1680kv 75mm long motor, 12.7 oz w/ connectors
7s 7700ma 106F, 29.1v-26.1v, 94.4A, 118.3oz T, 2475 W, 39,225 rpm, 1501 kv under load, 194 mph eflux

36-60-1500 Motor, 85HV ESC, Wemotech Midi Fan, 74mm exhaust diameter and thrust tube extends 9.25" beyond rear of fan, Medusa's Power Analyzer Plus system
8s 3850 Thunder Power Extreme pack heated to 105F before testing (cold in my work area).
Volts Amps Thrust oz Watts RPM
29.3 81.8 127.4 (7lbs 15.4oz) 2429W 38525 RPM
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Old Aug 04, 2009, 09:50 PM
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Braintree, Essex
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Good work Carl
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Old Aug 04, 2009, 09:56 PM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
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so it would seem the midi is close ....can you test the midi with the same motor as the DS-51?
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Old Aug 05, 2009, 12:28 AM
DELTAS RULE
corsair nut's Avatar
tehachapi, CA
Joined Jan 2006
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looks to me that given the same watts, the 2 fans are basically identical in performace. so much for the old saying that the midi falls short of the ds in the upper watt ranges...i mlove my midi. it has been dead smooth, and i havnt had to touch it in over 50 flights between the 1,5Y and the 2Y ive used in it.
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Old Aug 05, 2009, 01:16 AM
smug in granny panties
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NorCal Silicon Valley
Joined Aug 2002
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yeah for sure! only reason midi fell short was cause it just didn't reach the higher power levels. Now the field is more even. But if we look we realize it''s the same all the way up for fans, given watt levels can attain similar results depite what fan it is cause it just takes a certain amount of power to move a certain amount of air. Only modifier is drastic differences in efficiency.

Barry


Barry
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Old Aug 05, 2009, 03:18 AM
Julian T
Fleet, UK
Joined Jun 2005
519 Posts
Interesting results Carl. Does beg the question if the DS 51 is worth the extra. Looks good though That timing is pretty hard on the Lehner - I use 0 to 2 degrees on Lehner and Hacker 2 pole motors and have found current draw drops with virtually no impact on output.

Julian
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Old Aug 05, 2009, 03:31 AM
Team White Llama!
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Maybe compare to HET 9305 next?
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Old Aug 05, 2009, 03:33 AM
smug in granny panties
monkamarm2000's Avatar
NorCal Silicon Valley
Joined Aug 2002
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I would say yes cause then with new cells and motors coming out the stronger Carbon rotor should attain even higher levels now. Wouldn't be too surprised to see close to 4kw high rpm DS setups happening in our future. But Midi is still bang for the buck and performance out for what goes in the best fan ever made.

Barry
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Old Aug 05, 2009, 05:16 AM
EDF Nut
carl rich's Avatar
Cincinnati
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Without letting the cat out of the bag too much I will mention that at a lower watt input level the DS seemed to perform better than the Midi. Details in RC Sport Flyer next issue.

Would be interesting to see what happens w/ much more power. Around 3500w. This set up was in my Eliminator and begged for testing. Time becoming more precious. Twins due in about 2 weeks. Putting the DS back in the Eli to fly. Have to be ready for E-Jets.
For what it is worth the DS rotor seems sooo light weight and thin that it just seems there must be an advantage. It's also very rigid. I hope to do more testing in the future. Maybe backing off the timing would lower the current / watts and then it's more efficient at these higher input levels? Too late now. Fan back in Eli, nearly. It sounds fantastic in flight. Not many high power EDF sounds I don't like.
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Old Aug 05, 2009, 09:06 AM
DELTAS RULE
corsair nut's Avatar
tehachapi, CA
Joined Jan 2006
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to me, the DS sounds kinda anoying. the midi has a real sweet sound when its installed correctly, and running smooth. the differance in performace dosnt justify the cost, other than the weight of the unit itself...but a few oz extra in the larger jets...honestly...does it make a differance?

it would be interesting to see what the differance would be in less than perfect duting too, or which works better with limited FSA on the inlet.
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Last edited by corsair nut; Aug 05, 2009 at 09:18 AM.
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Old Aug 05, 2009, 09:20 AM
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I think all fans are broadly similar, construction and reliability still count for something.

I have an idea that each fan motor combo has a certain 'Sweet' spot in RPM, current draw etc. where it is at its peak. Say on a DS75 with a Neu 1527 2.5D thats around 4,100 Watts, below that the thrust drops in a step, above that the amps climb by a step, the step up and down is in the largest proportion at this point than at any other point in the range.

Of course, its easier to tell if you plot a precise liniar graph and of course my measuring kit is not needle sharp. But as a general observation I think this is true.
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Old Aug 05, 2009, 12:59 PM
EDF rules... :)
AirX's Avatar
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Quote:
Originally Posted by corsair nut
looks to me that given the same watts, the 2 fans are basically identical in performace.
I have been saying that for years...

Eric B.
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Old Aug 05, 2009, 01:26 PM
Official Boat Bum
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United States, NV, Reno
Joined Mar 2000
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I've not really heard a Midi sound "silky smooth", to my ears, even when they have been painstakingly balanced. While the DS sounds more shrill, they run "butter smooth" out of the box.

But then again, here we go with the sound thing again. All EDF's sound like motors and rotors, 'cause that's what they are, and nothing wrong with that. They all sound pretty similarly to me, give or take, within the range of pitch diversity. But I am happy to see so many get satisfaction out of the Midi, it's a great value for the money and that's one of the biggest challenges these days.
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Old Aug 05, 2009, 09:18 PM
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Mokena,Illinois -United States
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At what power level does the midi's blades start to flatten out at? What is the max it can handle watt wise vs. a shubi fan? I would think the shubi will handle higher power without self destructing.
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Old Aug 05, 2009, 10:18 PM
Registered EDF abuser
Scarey's Avatar
Michigan
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Quote:
Originally Posted by lavochkin
At what power level does the midi's blades start to flatten out at? What is the max it can handle watt wise vs. a shubi fan? I would think the shubi will handle higher power without self destructing.
The MIDI has been pushed close to 4Kw without destruction.

Scarey
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