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HelicopterTurbine Helicopters › custom mechanics for Wren 54 - questions
09-06-2009 02:00 PM  8 years agoPost 1
U.S.U.L

rrApprentice

Poland

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Hi

I'm interested in building custom mechanics for Wren 54 gas turbine with stock Wren gearbox.

I spent whole week reading and searching this forum but there are still a lot of things i don't quite understand and want to ask You:

1) On Wren's website the gearbox output starts from 4300 rpm - is that the idle rpm?
I would like to use HD clutch from century predator.
While it is designed for nitro engine which idles at 2000rpm i realize it will engage too early causing the rotor to rotate at turbine idle...

2) Is there any other solution to disengage 2-stage turbine output from rotor at idle?

3) I would like to build custom frame and mounts for it - can i use second stages's flange as a main support point for mounting it leaving gas turbine hanging unsupported?

4) Is it possible to mount it so the gearbox output is facing down instead of up?(i've seen one sph5 mounted like this)

5) Is it possible to mount it backward direction(turbine inlet facing tail rotor). Can i reverse the exhaust so it would not catch too much air(should i expect problems with this) in FF flight? Is Wren selling straight 90 deg exhaust?

6) What is the diameter of threaded gearbox output shaft?

7) Is Wren 54 gearbox output turning CW or CCW? Possible to reverse?

8) Where can i buy 15mm diameter mainshaft and 3 bladed rotorhead for it? I know vario XLC and rotortech Zealous II uses one, are there any other alternatives?

I will be really grateful for Your help!

Tomasz Patan - Revoflite

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09-09-2009 03:33 AM  8 years agoPost 2
Doug C

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Northern CA

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U.S.U.L.

I own a Predator Max 90 with the Wren 54 conversion and I will try to answer some of your questions as they apply to mine.

1) On Wren's website the gearbox output starts from 4300 rpm - is that the idle rpm?
--> that is Turbine RPM, 43,000 not 4,300

I would like to use HD clutch from century predator.
--> that is what it is designed for...

While it is designed for nitro engine which idles at 2000rpm i realize it will engage too early causing the rotor to rotate at turbine idle...
--> works like a champ on mine, at Turbine idle (around 45K rpm) the 2nd stage is not moving the rotor blades, movement starts around 50K Turbine rpm.

2) Is there any other solution to disengage 2-stage turbine output from rotor at idle?
--> NO

3) I would like to build custom frame and mounts for it - can i use second stages's flange as a main support point for mounting it leaving gas turbine hanging unsupported?
--> NO, the turbine must be supported, the weight will snap the 2nd stage.

4) Is it possible to mount it so the gearbox output is facing down instead of up?(i've seen one sph5 mounted like this)
--> YES, according to other threads in this group, it is not a problem for the new version 2nd stage gearbox

5) Is it possible to mount it backward direction(turbine inlet facing tail rotor).
--> yes, the turbine doesn't care which way it is pointing

Can i reverse the exhaust so it would not catch too much air(should i expect problems with this) in FF flight? Is Wren selling straight 90 deg exhaust?
--> would require a custom exhaust setup

6) What is the diameter of threaded gearbox output shaft?
--> 5/16-24, same as the OS .91 family of engines

7) Is Wren 54 gearbox output turning CW or CCW? Possible to reverse?
--> Don't know, never looked, but the 2nd stage turbine wheel is what dictates rotation and that would have to be changed if you wanted to change direction

8) Where can i buy 15mm diameter mainshaft and 3 bladed rotorhead for it?
--> No idea, maybe someone else can answer.

I know vario XLC and rotortech Zealous II uses one, are there any other alternatives?
--> see above

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09-09-2009 04:19 PM  8 years agoPost 3
Doug C

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Northern CA

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CORRECTION

I may be in error on the prop nut size, it could be the metric equal of 5/16-24 US, OS states the Prop Shaft threaded area on their engines is 5/16-24.

Regards,

Doug C

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09-09-2009 10:17 PM  8 years agoPost 4
U.S.U.L

rrApprentice

Poland

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Thank You Doug!

I want to be able to lift 10kg camera and i guess that the clutch for predator conversion may not be enough.

Do You have any idea where i can get more suited clutch for this task?

Tomasz Patan - Revoflite

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09-09-2009 10:49 PM  8 years agoPost 5
Doug C

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Northern CA

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Other folks on RunRyder can answer in more details but mine has no problem lifting 20 lbs into the air.. It is iffy with the stock 720mm blades but with 810's (which I am using) or the bigger 850s, it will lift a truck

The Wren 54 is way more power then the Predator airframe needs,

Regards,

Doug C

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09-09-2009 11:19 PM  8 years agoPost 6
Bell Bloke

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UK

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I too can confirm that a stock Wren Predator with the standard clutch will easily run around with 20lbs on is back all day long

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09-10-2009 01:52 AM  8 years agoPost 7
heliman53

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Charleston, Sc

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With a two stage turbine you don't really need a clutch, nice to have sure but not absolutely needed. Craig B

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09-10-2009 09:54 AM  8 years agoPost 8
U.S.U.L

rrApprentice

Poland

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I really need a clutch system to disengage main rotor from turbine especially as it is going to be a video/film camera ship.

Actually the AUW should be around 25kg(55lbs).

What about century v2 HD clutch? http://www.centuryheli.com/products...m?prtnm=CN1006A

The most improtant question for me is if it will engage on Wren 54 idle rpm?
Is it direct fit to gearbox shaft?

Tomasz Patan - Revoflite

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09-10-2009 08:00 PM  8 years agoPost 9
Bell Bloke

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UK

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On both of my Predators the blades creep round at about 45rpm when the engine is at idle. The clutch shoes are attached to the output shaft of the gearbox on the second stage. It is possible to put yoour hand on the head button and stop the blades whilst the engine is running but I'm told by Wren that this is not recommended for long periods. I often hold the head at idle for 30 seconds or so whilst I check my data logger.

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09-10-2009 08:43 PM  8 years agoPost 10
U.S.U.L

rrApprentice

Poland

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On both of my Predators the blades creep round at about 45rpm when the engine is at idle.
That is a bad news, i hoped it wound not engage

Do the rest of You have same experience with wren/predator conversion and HD clutch engaging at idle?

I'm going to use 3-bladed rotorhead on 12mm diameter mainshaft and ~1m blades.

Tomasz Patan - Revoflite

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09-10-2009 09:19 PM  8 years agoPost 11
Bell Bloke

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UK

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Mine is the standard clutch, the clutch you listed may be fine.
I assume you are making your own extended boom?
How were you going to approach the 12mm mainshaft conversion? The frames are quite narrow and bigger bearings needs a bit of thought. You could step down to a 10mm shaft as you go into the main gear auto hub.

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09-10-2009 10:12 PM  8 years agoPost 12
U.S.U.L

rrApprentice

Poland

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I hope You are right, still i'm interested what other Wren 54/HD predator clutch owners would say about that issue.

Answering Your questions: I'm making custom G10 frame and mechanics with turbine behind the main shaft and camera head in front. Double mod1 maingear with fixed hub, XLC tailboom, bevel gears, various Vario bits, etc

BTW, what is the diameter of threaded pinion part that goes into the clutch bell?

Tomasz Patan - Revoflite

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09-10-2009 11:18 PM  8 years agoPost 13
Bell Bloke

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UK

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Threaded pininion size, I'm not sure on that one, sorry.

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09-11-2009 12:56 AM  8 years agoPost 14
Doug C

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Northern CA

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Guys,

My Wren is set at 42K idle and with that rpm, my rotor head is not moving

The following vid was over a year ago just as I finished assembly and before the rest of the mods such as boom, blades, canopy, etc and you can see the blades don't move at idle

http://www.youtube.com/watch?v=KR_XtkNoRr4

Doug C

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09-12-2009 10:09 AM  8 years agoPost 15
KIM JOHNS

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CORNWALL

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HI U.S.U.L

on my raptor 90 turbine the idle is set at 38k and my rotor never

moves. i could put it to 40k and it still would not move,

the predator 90 should not move at 40k and if it dont move at 40k

put it to 42k even 43k if it dont move. problem solved.

cheer kim

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09-12-2009 10:30 AM  8 years agoPost 16
U.S.U.L

rrApprentice

Poland

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Thanks Guys!

I didn't even know that there is a possibility to alter idle rpm.

One more question:
What type of gas do You use to start the turbine, how the container looks and where can i get one?

Tomasz Patan - Revoflite

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09-12-2009 06:15 PM  8 years agoPost 17
Doug C

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Northern CA

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What type of gas do You use to start the turbine,
--> initial startup uses a Butane/Propane mixture, then shifts to kerosene, start process is controlled by ECU

how the container looks
--> small aluminum pressure can.

where can i get one?
--> they come with the Turbine when new, otherwise can be purchased from Wren or 3rd party website.

Doug C

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09-12-2009 09:22 PM  8 years agoPost 18
U.S.U.L

rrApprentice

Poland

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Thanks Doug.

Is this ok for refilling onboard gas container?
http://www.toolstation.com/images/l...ebbig/42276.jpg

Tomasz Patan - Revoflite

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09-13-2009 05:04 PM  8 years agoPost 19
Doug C

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Northern CA

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I am not familiar with that brand, maybe Bell Bloke, MattJen, or others from the Euro side of the Atlantic can answer

Doug C

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09-13-2009 05:18 PM  8 years agoPost 20
Bell Bloke

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UK

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Hi again, I just use any old propane/butane mix I can get my hands on at the local hardware store.

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HelicopterTurbine Helicopters › custom mechanics for Wren 54 - questions
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