glennb2006

Hi there,

I am wondering if anyone here can help me out please, I am into marine modelling, and run several Zenoah 26cc engines, PUM version. I am wondering does anyone here know what parts are required (along with a supplier who has them in stock would be great!) to fit an aero prop onto these motors?

I am trying to set up a test bench so I can test run them after working on them, just nice to know they are going to be right before fitting into boats, I am thinking an aero prop is the easiest way to get some load onto the motor under test.

If anyone can advise on size of prop would be good too. (Bear in mind these motors run in excess of 17000RPM.

Cheers.

Glenn

arobatx

www.horizonhobby.com or www.bennettbuilt.com have the prop hubs. Us airplane guys run the engine around 9000rpms, and helicopter guys run em about 10000rpm, so I have no suggestion for you to get the same load, at the same RPM, for your tests between the bench and the boat. ( I assume you'll be pumping water through the water jacket on the cylinder)

glennb2006

Hi Chad,

thanks for the links, I'll give them a go. Yes, I will run water through from a header bottle, gravity should be fine to cool the cylinder and pipe.

Glenn

pe reivers

A 16x8 menz-s prop would load the engine to 3.7hp at 10,000 rpm.
That seems about right for a 26cc boat engine on healthy breathing mufler.

glennb2006

Thanks Pe,

I'll factor that prop. into whatever I end up getting. Hitting blanks so far with Horizon refusing to ship outside USA. I am hoping (in fact I know) the engines I am dealing with are over 5 HP.

I'll get there in the end though.

Goedenacht. Dank je.


Glenn

pe reivers

Be careful.
5hp will need the engine to run over 14,000 rpm. Not all props will allow that without exploding. Tip speed should not exceed Mach 0.8

Whistling Death

glennb2006
Check out Tony Clarke over in Germany.
http://www.toni-clark.com/index_en.htm
You should have no trouble getting what ever you need from them for any Zenoah engine.
Too bad they don't have a distributor here in the US because I'd love to have a couple of their 90 degree carburetor intakes.

glennb2006

Thanks for that, glad you said it too, the engines when tuned will run in excess of 18000RPM when flat out, more with light loading.

Glenn

pe reivers

If you want to go up in rpm, Use an 11/11 prop, which will have a load of about 4.5 hp at 16,000 and 13540 rpm at Mach 0.6 tip speed

Antique

My Feedback: (4)

Try that on your Chinese "el cheapo" 26..Wear a shield or don't stand too close...Zenoahs have been doing that BEFORE the new wave of Chinese engines were a gleam in somone's eye...[>:]

glennb2006

Thanks Pe,

I appreciate your input. All I am trying to do here is have a bench run set up so I can:

1. Know the engine starts and runs OK
2. Put a little time on the engine under load
3. Hopefully be able to have some comparison on outputs with different pipe lengths.

I was not aware of issues with prop tip speed approaching Mach.

I am now. Might have to look at allternatives.


Thanks again though - all input is welcomed.

Glenn

pe reivers

It will work. Good luck.