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HomeAircraftHelicopterGasser Model RC HelicoptersOther › Electric Fan on a Gasser
04-07-2010 01:33 PM  8 years agoPost 21
brw0513

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Brisbane, Australia

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I'd really like to do a test to compare the air delivery of a radial fan (say a Radikal fan at 10,000rpm) against an axial fan like the SUNON unit I mentioned earlier. Just not sure how to do it nor how to measure results.

Is there such a thing as a "cfm meter"?

I'm thinking about this stuff because I'm going to put a Zenoah 20cc engine into a Blitz Avro airframe. My current thought is to use a Radikal fan and shroud since it is easy (in theory of course) to mate it with the Avro driveline. But theory and reality are sometimes different, so an alternative such as a dc fan to provide air flow is my Plan B. Pros and cons of course.

Ian B

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04-07-2010 01:50 PM  8 years agoPost 22
rotaryfalcon

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S.E. USA

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If we are looking at the same type of fan, a small axial fan in a square frame, I am afraid it just wont have the capacity. 23cfm is not a lot. Next time your computer fan is on hold your hand back there and see. I have a friend flying a 4 stroke with a small EDF stuck through the front of the fan shroud just above the head, cools very well. You dont need a very big one as they move a TON of air. If you dont have a gen. I would not fly with out a seperate battery for the fan. The 700 Rex setup sounds ideal as there is a way to regulate the fan. Its easy enough to experiment with though with an on/off switch. Your run time would be reduced though over regulated as the fan is WTFO. Still will tell what you want or dont want to know.

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04-07-2010 03:21 PM  8 years agoPost 23
shawmcky

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Isle of Wight,United Kingdom

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Yep ,the regulated ,controlled system with a generator.
described sounds like the way to go rather than have the fan running at full tilt all the time.

Team- unbiased opinion.K.I.S.S principle upheld here

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04-07-2010 03:24 PM  8 years agoPost 24
shawmcky

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Isle of Wight,United Kingdom

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How do the large scale guys get on
with gas powered heavy helicopters on summer days for cooling?The temps inside the fuselage must get very high as some of these models are in excess of 30 pounds.

Team- unbiased opinion.K.I.S.S principle upheld here

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04-07-2010 03:29 PM  8 years agoPost 25
copperclad

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NY

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On my old Trex 700g 26cc gx gasser i removed the cooling fan "predator" and installed a GWS EDF intergrated with the Carbsmart controller with a esc. As the engine would warm the edf would turn on and ramp up or down depending on the engine temp. Everything was set through the carbsmart interface.This system provided better engine temps with diffrent loads and outside temps.Also it would shut off after the engine would cool down. And yes it provided a big increase in power and allowed the engine to respond faster and rev higher due to the lack of spinning that monster predator fan. Remember this is the same reason why they did away with mechnical fans on cars years ago. People told me here on Runryder that i was crazy and didn't know what i was talking about. But they never tried it for themselves. You will need a manual reset limit switch embedded in the head in case the edf fan craps out. Or you can use the venom temperature failsafe unit, that will cut your throttle to a preset position if the engine gets to hot. Im still debating on converting my MD500 scale Radikal to this system because it worked really well on the Trex700g. I was using a 2s 5000mah pack to power the servos,ignition,and edf. I think the jewel would work great for this. The edf only uses 8-10amps. Also the heli sounded cooler than sh@t, when the edf would ramp up
Hi SkySurfer

great post , very interesting information , thanks for posting

.

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04-07-2010 03:56 PM  8 years agoPost 26
Justin Stuart (RIP)

rrMaster

Plano, Texas

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Couldn't you use the crankcase pressure to drive a Perry oscillating pump to pump coolant through the PUM head to a small radiator? Maybe the coolant flow rate wouldn't be sufficient using only crankcase pressure and a diaphragm pump?

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04-07-2010 04:31 PM  8 years agoPost 27
Machinehead01

rrVeteran

Lower Michigan

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Yes it works..
I have use the perry style pump to run water through my weedeater boat. My boat is clutched and can sit and idle all day with just the lake water from the pump passing through. The trick would be to get a good enough radiator. I have seen a cut down automotive transmission cooler work on a water cooled go kart.

Tom

"You judge according to the flesh; I am not judging anyone."

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04-07-2010 05:19 PM  8 years agoPost 28
rotaryfalcon

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S.E. USA

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I had already thought of water cooling for my 4 stroke, as suggested by a member here, I guess wrapping aluminum coils around the cylinder and head and using a perry pump to a form of radiator would work, but weight, something a heli needs to avoid, is probably going to, be an issue. I had thought of making a rad. out of aluminum tubing amd placing it on the boom braces in the down wash of the rotor, but the weight and complexity just didnt seem worth the end result, which is probably poor cooling(for this appilcation).

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04-07-2010 05:21 PM  8 years agoPost 29
Justin Stuart (RIP)

rrMaster

Plano, Texas

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What if you used something less dense like Ether for the coolant instead of water/ethylene glycol. Or maybe even Freon?

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04-07-2010 07:10 PM  8 years agoPost 30
Markus

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Montreal

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http://www.frozencpu.com/products/2...30c95s157#blank

We could use maybe a computer radiator cooling system...?

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04-07-2010 07:14 PM  8 years agoPost 31
shawmcky

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Isle of Wight,United Kingdom

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Looks just right
even got mounting points for an axial cooling fan

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04-07-2010 07:26 PM  8 years agoPost 32
rotaryfalcon

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S.E. USA

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Thats unbelievebly cool!(on pun)

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04-07-2010 07:36 PM  8 years agoPost 33
Justin Stuart (RIP)

rrMaster

Plano, Texas

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If you pulled off the metal fan and shroud, replaced the Zenoah PUH head with a PUM head, added a small radiator, oscillating pump, coolant, and electric fan. How much extra weight are we talking here?

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04-08-2010 05:20 AM  8 years agoPost 34
SkySurfer

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usa

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hadn't been thinking so grand but there is no reason why the fan couldn't be arranged to be variable speed with some form of safety net back-up. It might also be a good option to simply have different fan speeds for each flight condition.
Plug the 3wire that comes from the ESC into the servo port of the carbsmart. The carbsmart will send a signal to the esc and will vary the efd speed according to engine temperature. Also with the carbsmart controller, you can set the high and low limits that you want the edf to run. This system saves alot of power and offers better temperature
management, compaired to running the edf off of a "Y" connecter on channel 3. When you start the heli the edf will be off till the engine reaches temperature. Then the fan will slowly start to ramp up to cool the engine. Also by having the EDF system, there is no heat soak when shutting off the motor or using the throttle hold switch. The EDF will start to ramp down and then shut off after the engine cools down. I purchased the GWS EDF fan and Esc for about $40. I had the Carbsmart controller already. The total system was maybe $100. My Trex 700g was not able to tic toc with the mechanical fan. But once i removed the fan and went with edf setup, it could. There is no doubt in my mind that it added at least 10-20% more power. The weight of the extra battery didn't matter that much. I didn't even need a cooling shroud on the engine, because the edf put out so much airflow. I'll post a diagram of how to wire it.

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04-08-2010 05:22 AM  8 years agoPost 35
SkySurfer

rrApprentice

usa

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If you pulled off the metal fan and shroud, replaced the Zenoah PUH head with a PUM head, added a small radiator, oscillating pump, coolant, and electric fan. How much extra weight are we talking here?
Theres no need for liquid cooling. A edf alone provides enough cooling for the job.

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04-08-2010 05:48 AM  8 years agoPost 36
SkySurfer

rrApprentice

usa

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Here you go

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04-08-2010 06:02 AM  8 years agoPost 37
SkySurfer

rrApprentice

usa

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I used this fan, witch provides a insane amount of airflow @7.2 volts. I almost thought that the amount of airflow coming from this was going to affect the heli's hover. But i dialed it down on the CSM pot screw. I also changed the motor to a brushless for extra reliability. FYI only uses 3.39 amps FLA

http://www3.towerhobbies.com/cgi-bi...p?&I=LXHHP1&P=7

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04-08-2010 10:14 AM  8 years agoPost 38
brw0513

rrApprentice

Brisbane, Australia

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Thanks for sharing SkySurfer.

Did you make a custom shroud to channel the air over the cylinder head or was the output from the EDF just directed over the head?

Ian B

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04-08-2010 11:56 AM  8 years agoPost 39
SkySurfer

rrApprentice

usa

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EDF was over the head.

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04-10-2010 02:09 PM  8 years agoPost 40
Dilbeck

rrElite Veteran

Springdale Arkansas

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Its about time somebody started addressing the cooling of a nitro engine. The cooler the leaner = more power.

Clint

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