Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[craig dickson]

 Hi Ian
It might be worth you opening up a new topic on this Zenoah build topic. That way if you need any advice etc it should come in volumes and will make for very interesting reading. I for one will contribute if I can add anything useful.
Just on the pictures, I am not familiar with the blue CNC mount shown. However the thing that does strike me is that the drive hardware shown is for submerged drive (including the coupling, and prop tube/shaft rudder etc). If you are intending to put the Zen in the Apache mono hull you will need surface drive components.
Oh by the way, I am glad to see the ports taped up to prevent dirt ingress during the build process.
Cheers
Craig

[spearfish99]

Hi Craig,
  Sorry to hijack your original posting anyway!
  Interestingly, the Apache hull that I have ( the one with holes all over the transom) actually has a flex shaft outer fitted to an under hull strut giving parallel drive and then holes for a Aeromarine rudder mounted on the centreline of the transom. It doesn't seem to have been intended for surface drive. Is there any particular reason that it should have to run surface drive? I am a bit old fashioned anyway and do like my bits on the bottom of the hull if I can get away with it
 The hardware in the photos came with the deal and was for the Huntsman hull. Given what was included, I was amazed that I was the only one to bid on it

[craig dickson]

 Hi Ian, no worries on the topic going off thread.
However, just to put the topic back on thread, I want to put a different twist to it:
I included a video clip earlier of my Zenoah powered Thunder being tested. What the clip did not show was the process of changing the props being tested. And I am an advocate of having very sharp propellers for best performance.
What was not shown was what happened when I removed one of the props using a thick cotton rag for safety.....or so I thought.
My thumb slipped off the smooth blade and into its leading edge as it suddenly came loose to take off. Thankfully my thumb nail stopped the cut going deeper than it did. The purpose of my contribution here is to demonstrate what happens in an instant when one’s concentration is lost for a split second. I learnt a lesson last Sunday.
The photo below shows my thumb nearly a week later and on the mend:
If you are using sharp propellers, please take care.

Cheers
Craig

[spearfish99]

OUCH!
  I don't think that sub surface props need to be as sharp as surface ones.

[Martin (Admin)]

Jumping Jehoshaphat Craig!
  Spoiler warning please!!!     

[martno1fan]

Hi Ian I sent you a pm about your gear.Basicly what you have is whats known as a dropped mount I think the design is from top secret ,very good mounts and yes has a built in coil mount for the grey coil.Header looks very short as its been cut,did it come with a tuned pipe ? if not you may need another header too as it looks a bit short.
Mart

[craig dickson]

Hi Ian
Just to add to Mart's comments: I do hope you are going to use a tuned pipe with your stock Zenoah as these motors perform surprisingly well with one. Just on the header length, I just measured my header on my Zen (measuring from the top along the centre going round the bend to the flange). Mine is 12.5 cm. I use the Prestwich Competition Pipe and this length is ideal for that.
Cheers
Craig

[spearfish99]

Hi Craig,
 Thanks very much for that. With the info from you and Mart, I should be well set once I start building.
  This evening, I moved the grey coil to the top of the mount on the built in mounting points. I have also ordered one of the Prestwich throttle bellcrank set ups so that I can have a linear throttle connection.
 Simply have to decide which hull to use. I addition to the Apaches, I have a Busby. I call it this as it is an unknown 54" hull bought from someone's widow in an estate sale. Called Busby after BT's advertising character of the 70's as it is large and very yellow!!!
 It has no holes in it, comes already fitted with 5" mounting rails and is quite a nice design. Tried to add a pic but my digital camera produces too big files for this site and I can't get them to shrink tonight for some reason

[craig dickson]

Hi Ian
It is a shame the photos wouldn't upload as I'd like to see the two boats. Just on the throttle bell crank the first photo here shows the Prestwich Bell Crank first used on my stock Zenoah. Their bell crank is very nicely made and of very good quality. The issue I had after several hours running was that the throttle butterfly had a tendency to stick in the open position and with this set up closing the throttle relies entirely on the strength of the return spring. So once stuck open I could not shut the throttle down.

To cure this I fitted a cruder bell crank in the horizontal plane with a home made alloy bracket bent at 90 degrees. This time there was a piano wire connection to the throttle arm (this time on a copy of a 644 carb). This proved a more reliable set up as the servo can close the throttle not relying alone upon the butterfly return spring should the butterfly stick at all.

Better still in my other boat the Prestwich bell crank is fitted off the engine mount to the side of the boat and with decent Dubro linkages for smoother connections (just visible top of photo). The advantage in this photo is that should the engine move slightly forward at full power on its mounts (if using a surface drive with big flexi gap at prop end) it will have less impact on the throttle position as the lever feeds in from the side. Also this set up keeps the linkage out of the way if using a belt to start the motor. Hopefully food for thought despite staying off topic

Cheers
Craig

[spearfish99]

Hi Craig
 Thanks for those. Certainly food for thought
 

[martno1fan]

Def go with option 2 in Craigs pics ,you def need a way to close the throttle and not have to rely on the return spring.You can also use nylon bellcranks as used on planes they work just fine.Doesnt take much to open and close the throttle.
Mart