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Old Dec 05, 2012, 10:40 PM
Extreme CNC Alloy EDF
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I read pretty good, you said;
"Ok so how do you explain the lower amount of amps your getting??? Everyone that is a large EDF enthusiest knows that the Ramtec has always been an amp hog!"
"thrust for thrust just saying it doesn't seem to add up amps or performance."

So what doesnt add up? Explain the lower amps? Efficiency I suppose Amp hog? maybe if its not set up right.

Now you say you had to pull high amps to get 20lb on 12s, well guess what, no one would be surprised! You gotta pull high amps to get 20lb on 12s with any fan.

I get 20.9lb thrust at 141.4A on 14s, with a Sunrise 200A controller the fan runs nice, affordable setup too. Your choice of fans is completely personal, no one is going to argue with you on that, but that wont change the figures I am achieving nor the confirmation of such by customers already flying the fan.
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Old Dec 05, 2012, 11:06 PM
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We needed 190 plus amps to get 20lbs of thrust on the Ramtec, 150 on the Dynamax, DS-94 152 amps to get 22lbs.

Again this is on 12s, I can run 2 6s 8000mah packs and get decent flight time with out dealing with higher amp controllers and 3 batteries to fly.

I gave you credit for your 115 amp setup with 17lbs that is nice! My interests are different since I want to stick with 12s and get close to 20lbs...
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Old Dec 05, 2012, 11:28 PM
deltas are cool
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i think the kv si right in the sweet spot ...most guys that ran the Ramtec early on on EDf tried using the same motors that the dynamax was using ,hence they got tagged as amp hogs ...it pays to play around with motors to find the right one i give you guys credit for trying different set ups . i have a 800 motor on order to make a 115mm fan for my BVM fury.
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Old Dec 06, 2012, 01:47 AM
Extreme CNC Alloy EDF
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I have run the Dynamax also, done a few fans with Scorpion 4035-630Kv motors for customers, I have seen 100.5A/4370W for 6.6kg thrust.
I have also run the HET 700-98-670 and seen 97.5A/4425W and 6.8kg thrust.

I also had a motor custom made for me by the old Hacker factory to suit my Ramtec fan, a 4035-560Kv outrunner, it produced 6.5kg thrust at 96.8A/4200W with the Ramtec rotor. Looking at these figures there is no difference in these 2 rotors if correctly matched to motors.

What motor did you use in the 150A 12s system to produce 9+kg thrust with a dynamax rotor? thats gotta be around 6600w right? how about posting up some details for us.
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Old Dec 06, 2012, 09:13 AM
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Quote:
Originally Posted by Extreme_RC View Post
I have run the Dynamax also, done a few fans with Scorpion 4035-630Kv motors for customers, I have seen 100.5A/4370W for 6.6kg thrust.
I have also run the HET 700-98-670 and seen 97.5A/4425W and 6.8kg thrust.

I also had a motor custom made for me by the old Hacker factory to suit my Ramtec fan, a 4035-560Kv outrunner, it produced 6.5kg thrust at 96.8A/4200W with the Ramtec rotor. Looking at these figures there is no difference in these 2 rotors if correctly matched to motors.

What motor did you use in the 150A 12s system to produce 9+kg thrust with a dynamax rotor? thats gotta be around 6600w right? how about posting up some details for us.

It's a prototype motor we tested for a manufacture, can't offer any details on it unless they decide to go with it.
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Old Dec 06, 2012, 09:16 AM
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It's interesting how often I hear people say they only get 4300-4500 on the 4035-630, I know of about 4 of those including mine that are at 5000-5400 at 115 amps. 12s 30c 5800 mah's.
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Old Dec 06, 2012, 09:27 AM
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^^
Brian:

Me too. I am getting 5300-5600 watts on my Dynamax/Scorpion 4035-630KV setup on 12S (turnigy 6000 mah Nanotechs) at 120 amps.

Ed
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Old Dec 06, 2012, 09:42 AM
Pursuit of Happiness
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Back in oct. 2009 I was getting 98 amps, 4200 watts, 12 lbs 6 oz installed thrust in my TJ A-4 with the Dynamax/4035-630 KV scorpion. 3.5 inch tail pipe (90mm)

I was only running 12s 30c 5000 mah TP packs.... I'm sure newer and better packs are part of the reason. Every year they seem to get better. Add to that different ducting, thrust tube size, elevations and weather..... hard to see the same numbers

http://www.rcgroups.com/forums/showt...1126285&page=4
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Old Dec 06, 2012, 09:57 AM
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Quote:
Originally Posted by bri6672 View Post
It's interesting how often I hear people say they only get 4300-4500 on the 4035-630, I know of about 4 of those including mine that are at 5000-5400 at 115 amps. 12s 30c 5800 mah's.
Bri, I think it has a lot to do with the motor and also some fluid dynamics...

I haven't seen vids of but shube and BVM claim 20lbs of thrust at 5000 watts...

Maybe also how light the rotor is has something to do with watts to thrust...I really don't believe EDF is using watt efficiently but we haven't had almost 100 years on EDFs like turbines have had...

good times
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Old Dec 06, 2012, 10:00 AM
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Originally Posted by Extreme_RC View Post
...Now you say you had to pull high amps to get 20lb on 12s, well guess what, no one would be surprised! You gotta pull high amps to get 20lb on 12s with any fan....
+1 on 20lbs with one fan....

If weight and space are avialbe, 2 fans are more efficent than one IMHE
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Old Dec 06, 2012, 11:14 AM
Pursuit of Happiness
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The other huge problem with thrust numbers is how those numbers were had.

I've seen pictures of Daniel Schubeler and BVM's thrust stands, they look like scientific equipment..... high end bearings, aluminum, and expensive strain gauges. Now Stu and myself use homemade stands with fish scale and hardware store parts.... installed numbers are even less accureate. Wheel resistance, unlevel ground, awkward postion to use a fish scale or whatever you use
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Old Dec 06, 2012, 12:30 PM
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The other huge problem with thrust numbers is how those numbers were had.

I've seen pictures of Daniel Schubeler and BVM's thrust stands, they look like scientific equipment..... high end bearings, aluminum, and expensive strain gauges. Now Stu and myself use homemade stands with fish scale and hardware store parts.... installed numbers are even less accureate. Wheel resistance, unlevel ground, awkward postion to use a fish scale or whatever you use
veritcal thrust stands seem like the best homebrew...no moving parts...use a blast shild and long servo wires for safty.

Can't test installed ducting thrust with them though...
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Old Dec 06, 2012, 02:51 PM
Extreme CNC Alloy EDF
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Australia
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Quote:
Originally Posted by bri6672 View Post
It's interesting how often I hear people say they only get 4300-4500 on the 4035-630, I know of about 4 of those including mine that are at 5000-5400 at 115 amps. 12s 30c 5800 mah's.
Whats most interesting is I post ALL relevant data, amps, watts, and THRUST. So I am getting X thrust at X watts. Easily verifiable by others with similar readings, and has been verified in the past by guys on this forum.

Now I also state clearly what packs I am using, and they are 2 yr old 30-35c packs, nothing special, dont get time to pull new ones out of stock as I never have stock long enough and my packs are still flying my planes fine.

If I hooked up a new pair of 6000mah 40c packs I would certainly get a lot more thrust and a corresponding increase in consumption.

By the way you are not getting 5000 watts, you are consuming 5000 watts, whether that consumption is being converted into rotating speed and thrust is a different question altogether.
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Old Dec 06, 2012, 03:42 PM
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Quote:
Originally Posted by Extreme_RC View Post

By the way you are not getting 5000 watts, you are consuming 5000 watts, whether that consumption is being converted into rotating speed and thrust is a different question altogether.

115 amps 5300 watts and 16lbs of thrust with a 10" long 3 3/8 diameter thrust tube, forgot to measure the efflux thou.... Is that better?
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Old Dec 06, 2012, 05:01 PM
Extreme CNC Alloy EDF
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Australia
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Originally Posted by bri6672 View Post
115 amps 5300 watts and 16lbs of thrust with a 10" long 3 3/8 diameter thrust tube, forgot to measure the efflux thou.... Is that better?
This is a Dynamax 127mm (5") fan unit? 5300w to get 7.3kg thrust doesnt sound all that efficient, I see 7.7kg at 4800w with the Ramtec setup. I will roll up a thrust tube 100mm diameter (80% FSA) and test it to see what sort of amp increase we get.

As for your thrust tube, you sure on the size? 3 & 3/8 inch is about 86mm, that seems extremely small, 80% FSA for a fan with 125mm rotor and a 57mm hub is 100mm.
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