Thread Tools
Jan 28, 2018, 06:49 AM
The best in EDF since 2005
Extreme_RC's Avatar
Thread OP
Quote:
Originally Posted by Arngeir Blakseth
I have done tests with a Neu 1920 1Y 510kV which is basically the same motor as HET now is offering. It worked very well on 18S in a Dynamax, have also tested it in a TJ 120 shroud with a 11-blade cut down Ramtec rotor and if I remember correctly that was a 8.5kW setup. So 18S on a full diameter Ramtec may be a bit hot.
Yes its more likely going to be a 16s setup, time will tell, Tony and I will get to testing it soon enough. Appreciate your info Arngeir, always welcome!
Latest blog entry: Extreme RC AUSTRALIA
Sign up now
to remove ads between posts
Jan 28, 2018, 08:43 AM
Registered User
EDF Crazy's Avatar
Quote:
Originally Posted by Arngeir Blakseth
FSA of the Ramtec and Dynamax is very close to each other. The hub diameter is almost the same (+/- 1 mm) and the shroud ID is also very close, no surprise as they are both sold as 5" fans. (127mm). So comparing the performance of these two fan units to each other is a fair apples to apples comparison as far as I can see.
Then why have I heard the dynamax is closer to a 120mm fan on many occasions? If this isnt the case then why does the dynamax use a much smaller thrust tube outlet diameter? 3.75" If I recall, and performance figures seem to me to be closer to a 120mm fan. surely it cant be so inefficient. Just looking for clarification.
Jan 28, 2018, 09:06 AM
****member
Arngeir Blakseth's Avatar
Why people say that I don't know. I have owned both fans and they are very similar in dimensions.

As far as outlet diameter on the thrust tube, that largely comes down to rotor/stator design, fans are designed differently and the Dynamax fan can tolerate a smaller outlet diameter than other fans. It can be as small as 3.375" is what I have heard, but going a bit larger will give more thrust with the trade off being less efflux speed. A Ramtec fan is not happy with such a small outlet diameter, it is happier closer to 4".
Jan 28, 2018, 09:15 AM
Registered User
EDF Crazy's Avatar
Quote:
Originally Posted by Extreme_RC
I don't see you posting up your discoveries on the JF130 in the PAR Dynamax thread...
Correct, but I didnt see Par post things to 'ponder over' about other fans performances as a comparison to his product like you did in this thread. Seems like your attacking his product.


Quote:
Originally Posted by Extreme_RC
fact is the 10Ah 14s pack is lighter loaded
Only because your drawing 7555 watts from the 14s pack and the other 8400w, almost 900w more , so of course a higher c loading is being drawn from the other pack.

If you were to draw 7555w from both packs the 18s pack would have a lower draw on it.


Quote:
Originally Posted by Extreme_RC
w/h is not an indication of flight time.
Um.... its an indication of total energy. so is directly connected to duration.
Last edited by EDF Crazy; Jan 28, 2018 at 09:34 AM.
Jan 28, 2018, 12:29 PM
Registered User
erh7771's Avatar
Quote:
Originally Posted by Extreme_RC
...Oh yeah I imagine this fan will do 30lb easily straight out of the box, we just need to choose a motor and set it up...
I mistakenly hooked together a 16s cell config and did 26 lbs with the HET 590kv so 30 lbs un-modded is very achievable,

Even 26 lbs will fly tons of turbine sized jets on 10 ah + packs which are not expensive these days

Quote:
Motor mounts are no issue as mentioned, in fact I will be asking Tony next week about knocking me up a 56mm version so I can test some other motors, I just need to know what the bolt pattern is on the TP motors, 25mm or 30mm? As I wont be able to get one in my hands for a little while.
NICE !!!

I'm in for one of these as soon as he has one
Jan 28, 2018, 01:35 PM
Registered User
Thanks Mark

So I think my question is whats the largest motor I can fit in the aluminum shrouds
Jan 28, 2018, 04:34 PM
The best in EDF since 2005
Extreme_RC's Avatar
Thread OP
Quote:
Originally Posted by Air Head
Thanks Mark
So I think my question is whats the largest motor I can fit in the aluminum shrouds
50mm if they are my shrouds! You need to clarify which shroud you have, my original CNC machined housings started off at 45mm in the first batch, very long time ago, then went to 50mm for the last 3 years.

The current housing is the Ramtec original GRP molded shroud with all alloy stator and motor housing assembly internally, so the current housing 'can' be modified on the CNC program to increase the diameter of the motor section and decrease the length of the stators.
Latest blog entry: Extreme RC AUSTRALIA
Jan 28, 2018, 04:55 PM
The best in EDF since 2005
Extreme_RC's Avatar
Thread OP
Quote:
Originally Posted by EDF Crazy
Correct, but I didnt see Par post things to 'ponder over' about other fans performances as a comparison to his product like you did in this thread. Seems like your attacking his product.
I am questioning his figures, I did so in his thread and got flamed by all the fanboys, there is too much blind excitement and not enough understanding of the figures being posted. First thing he did when I questioned the g/w figures was to attack me personally & accuse me of selling him unbalanced fans, then when it was proved he never purchased anything from me he brushed it under the table rather than man up that he lied. I however am NOT attacking anything, I am comparing 2 like products.

Quote:
Only because your drawing 7555 watts from the 14s pack and the other 8400w, almost 900w more , so of course a higher c loading is being drawn from the other pack.
If you were to draw 7555w from both packs the 18s pack would have a lower draw on it.
And that's the whole point isn't it! If you were drawing 7555w from the Dynamax setup you wouldn't be making 22lb of thrust so the comparison would be pointless, the whole point is the Dynamax is using 900w more to make the same amount of thrust LOL.

Quote:
Um.... its an indication of total energy. so is directly connected to duration.
Yes it is an indication of energy, but it does not guarantee more flight time and is not the governing factor in this example...the figures quite clearly show the setup running the smaller w/h has longer duration
Latest blog entry: Extreme RC AUSTRALIA
Jan 28, 2018, 05:49 PM
Registered User
EDF Crazy's Avatar
Quote:
Originally Posted by Extreme_RC
And that's the whole point isn't it! If you were drawing 7555w from the Dynamax setup you wouldn't be making 22lb of thrust so the comparison would be pointless, the whole point is the Dynamax is using 900w more to make the same amount of thrust LOL.
I fully understood this but people reading might not have.

One thing I would like to see tho is the Eflux velocities of these different fans at different wattage level increments. Because if we look at just thrust then the Jetfan is winning hands down. If these fans are all well designed then there can only be a very small % of efficiency between them, and correct me if im wrong the the way I see it if comparing all three fans at a set wattage, the Jetfan is producing the most thrust and the least eflux, the dynamax the least thrust and the most eflux and the ramtec is a happy medium with eflux and thrust?
As long as your not generating much heat in your motor then that energy must be doing something , and i personally would like to see the full picture for comparison.
Jan 28, 2018, 06:00 PM
world's slowest builder
Air-Jon's Avatar
It's good to hear the Ramtec is still getting attention. I think we all recognize it's a great fan. The biggest bummer is that few MFGs are making airframes like the old ICDF airframes. The end of YA was a big hit. Many Turbine airframes are pretty useless for EDF and the inlets are too small for the size of the airframe for ducted fan use. JTM and sky e master and BVM are the only MFGs making composite EDFs in this business range...and JTM seems to be slowly moving toward the turbine world.

There are still many old ICDF kits to be built waiting for these fans though.

I will say that comparing test results between two different test fixtures is absolutely useless.

Unless the fans are tested in the same test cell...there is no point. I know this from being a test technician for 20 years. Have said this to Par too.

At these power levels, 900watts delta is in the noise without proper calibration. I would say absolute accuracy is optimisticly +/- 500w.

I think the best all around setup for the ICDF airframes would be a lightweight yet reliable 7kw (50mm) 18s, 22lbs thrust sustained system. This way you can use 3 inexpensive 5000 to 6000 30c mAh packs. Amps kept at 100A or less. These aren't same packs everyone already has to fly their smaller 6s foamy jets.

The 18s voltage issue should not be an issue. For anyone who values life, you should treat all DC voltages above 40V the same. All life threatening under the right (wrong) conditions.

Once the next leak in battery tech hits the market, I believe large EDF models will be all the rage. Until then, we just do the best we can, but will always take a back seat to the turbines. I guess I'm one of the rare ones who does not get turned on much by the noise and the mess of diesel fuel... I think EDF sounds so much better. Some people just have to make as much noise as possible. I like the sound of silence. I do envy the turbine guys flight time though....and the ability to totally disregard intake area.
Last edited by Air-Jon; Jan 28, 2018 at 06:32 PM.
Jan 28, 2018, 06:22 PM
Registered User
I'm sorry for asking the same question. let me put it this way

Whats the largest 50mm diameter motor available or recommended. (I'm just not familiar with these fan motors). Looking for the most power I can get to fit in the 50mm aluminum shrouds. I have some Big Screamer motors but have some reluctance to use them.
Jan 28, 2018, 06:34 PM
The best in EDF since 2005
Extreme_RC's Avatar
Thread OP
Quote:
Originally Posted by Air Head
I'm sorry for asking the same question. let me put it this way
Whats the largest 50mm diameter motor available or recommended. (I'm just not familiar with these fan motors). Looking for the most power I can get to fit in the 50mm aluminum shrouds. I have some Big Screamer motors but have some reluctance to use them.
LOL well that's more clear to me anyway I am only familiar with the HET 800 series from hands on, there are other 50mm motors out there like neu and certainly other Asian made motors, but I haven't had the time to do a lot of investigating so I am sure others could better answer this for you. The new 800-83-510 should be a good 16s motor with the alloy housing and ramtec rotor, it will theoretically take the most power due to being the largest mass in the range.
Latest blog entry: Extreme RC AUSTRALIA
Jan 28, 2018, 06:41 PM
The best in EDF since 2005
Extreme_RC's Avatar
Thread OP
Quote:
Originally Posted by Air-Jon
I will say that comparing test results between two different test fixtures is absolutely useless. Unless the fans are tested in the same test cell...there is no point. I know this from being a test technician for 20 years. Have said this to Par too.
I respectfully disagree with you on this, I have seen customers around the world rig up test stands from all manner of materials, as well as commercially made ones, and end up with the same figures that I have published, this is from 64mm right up to the 127mm fans.

I honestly don't think there is a lot of discrepancy in results published based on my experience of over 10 years testing just fans on various test stands, starting with wooden vertical ones onto scales with the smaller fans! Retesting 70mm combos on my current zero friction test stand I am seeing the same basic numbers that I first got in a vertical stand sitting on a set of 20kg bench scales.
Latest blog entry: Extreme RC AUSTRALIA
Jan 28, 2018, 07:04 PM
****member
Arngeir Blakseth's Avatar
Quote:
Originally Posted by Air Head
I'm sorry for asking the same question. let me put it this way

Whats the largest 50mm diameter motor available or recommended. (I'm just not familiar with these fan motors). Looking for the most power I can get to fit in the 50mm aluminum shrouds. I have some Big Screamer motors but have some reluctance to use them.
Neu 1925 1Y but it has a 400kV so will need maybe 22S in a Ramtec. I'm not aware of anyone that has tested such a combo though so what it can and will do is not known.
Jan 28, 2018, 07:30 PM
world's slowest builder
Air-Jon's Avatar
Thrust is the easiest measurement to get right but still likely to have some error. Voltage measuring circuits are also quite accurate these days. Currnet readings are the most difficult to measure correctly. Weather you are using a shunt or and inductive meter, 5 to 10% error is very likely. Now multiply that error by the voltage being used and the errors can grow quickly. So wattage measurements are pretty rough unless using calibrated and fixed equipment. You can disagree all you like, It's not an opinion, it's a know fact in the test and measurement world.

So if you are talking about Thrust/watts ratio at anything in decimal point range, you are kidding yourself if you are thinking it's accurate and universal.

Fan RPM, vs. thrust output and efflux for 100% FSA inlet outlet should be a known fact for any fan...with a standardized inlet lip. If someone would just measure this on a calibrated stand for each fan...nobody would need a thrust stand, just a good tachometer. Then if the community settled on a calibrated shunt to use for current measurement, we could talk much more real numbers around the world.

Then much is thrown all out the window because we put these fan in deeply ducted airframes....with non optimal ducting....and it's all wasted. Its likely different brands of fan handle the effects of ducting differently...as some have pointed out with how certain fans tolerate the back pressure of the exhaust ducting differently.
Last edited by Air-Jon; Jan 28, 2018 at 07:43 PM.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
New Product EXTREME CNC ALLOY 70, 80, 90mm & 127mm FANS / RAMTEC /JETFAN / CS 70mm Extreme_RC Electric Ducted Fan Jet Talk 67 Jul 18, 2019 12:39 AM
New Product Extreme 127mm Alloy Ramtec with the new 5075 inrunner! Extreme_RC Electric Ducted Fan Jet Talk 97 Jan 09, 2013 05:24 PM
Discussion Extreme's new 50mm inrunner in the Alloy Ramtec 127mm fan! Extreme_RC Australia 1 Aug 23, 2012 02:26 AM
New Product EXTREME RC's CNC Alloy fans - 64, 70, 90, 100, 120 & 127mm!! Extreme_RC Australia 23 Aug 24, 2011 12:39 AM
Yippee! Extreme RC's CNC Alloy 64-127mm Ducted Fans & Jet models discussion thread Extreme_RC Electric Ducted Fan Jet Talk 145 Jul 23, 2011 03:14 AM