Inverted Fans...

[mchristyuk]

Ok.. this has been bugging me for a while now..

What is going on with the craze of new models having cooling fans mounted upside down with the governor pickup on the clutch bell??

A typical helicopter fan works by sucking COLD air from the centre opening of the shroud and then directing that down over the rather HOT engine beneath..

As soon as you mount it upside down you've ruined it!.. the fan is now sucking HOT air up from the engine.. and then blowing it back down on to the engine...

Because the fan is now upside down you have to mount the governor magnet elsewhere.. with the clutch bell being the only realistic option..

The problem with that is as soon as your clutch wears and starts to slip a little the governor will add throttle and make the situation worse.

Even the new Vibe 50 looks guilty of this and that at least has the fan on the right way up! When I get mine I'll be cutting the shroud and mounting the sensor/magnet where it ought to be!

Rant over

Mark

[Ade_Law]

the idea is when you hot start you dont suck clutch dust into the engine.

i would rather have a cooler engine and just do your pre flights properly :-)

Ade

[mchristyuk]

Ade,

Exactly

I've had a few hot starts.. and never had a problem ingesting clutch liner into the engine..

Hot start.. happens once every 100 flights?

Cool running engine?.. every flight please!

Mark

[BobJ]

Hi

There are a couple of reasons, the main two are firstly the air gets drawn up over the crankcase which shouldn't be to hot, this cools the crankcase and then it gets blasted at a higher speed over the hot cylinder head.

Having the sensor mounted away from the engine means it isn't subjected to so much heat and vibration ( I have never had to replace a sensor on my Synergies yet!) and is generally easier to mount, I know that fitting some makes of sensors in the 600 N is a pain but the GV-1 sensor was easy and I expect Align's new govenor will be like wise.

Cheers
Bob J

[ChrisB]

Initially i thought the 600N sensor mounting was a right pain,but once you have sussed how to mount it,its fine

Both my 600N belt and Pro are giving excellent service with no sensor or engine cooling issues,in fact my Hypers backplates are cool to the touch after flight using magnum 30

The idea of a magnet on the clutch bell is crap,,thats why i assume,Align put theirs on the fan as per normal

[Disc]

Initially i thought the 600N sensor mounting was a right pain,but once you have sussed how to mount it,its fine

Both my 600N belt and Pro are giving excellent service with no sensor or engine cooling issues,in fact my Hypers backplates are cool to the touch after flight using magnum 30

Ah but who's fans are in those machines the soft putty one's or....

[ChrisB]

Ah but who's fans are in those machines the soft putty one's or....

My Pro has the G Force ally fan as the plastic one was no good,the Belt one has the original plastic fan and has done several gallons trouble free...

Align have updated the fan,so i assume that problem is no more..

[SRH990]

I've got the Align metal fan in mine together with an RL20 and Smart Carb, my 50 Hyper runs at just the right temperature and has very good power, cooling doesn't seem to be an issue at all.