Another BH Macchi C200 - placemarker

Just ignore the philistines Rob, I'd give my left one for that engine!

as kkw said ignore the quorn munchers :evil: its a proper aircraft that needs an oily in it not something that goes brrrrr [badass] . Are you flatting her by the way

The motive power is irrelavant, if it swings a prop, it works for me, but the laser is a thing of beuty, crafted from bar stock, no castings at all, from an engineering point of view, its a masterpiece of metal bashing

"Are you flatting her" - Geoff, I think I'll have to put a coat of satin clear on, if only to protect the vinyl and to seal the edges down.
"its a masterpiece of metal bashing " crafted yes, but bashing? Morris Marinas may have been bashed into shape, and at Lucas we could justifiably have been accussed of bashing out starters, but this isanother league entirely.
I am puzzled by the sleeve nut though. There's a stock hex nut and shaped prop washer, but then there's that sleeve nut with another larger washer. What puzzles me is what sort of prop it could be meant for as it would have to have a hub about 40mm thick for the nut to clamp down on it. I'd have preferred the usual style of nut + locknut supplied with most brands of 4 stroke.

When you are in production hi presicion engineering, as i am, then yes, its crafting, fairynuff the stuff we do can be considered art work, as is the laser

regarding the sleeve nut, i think there are 2 sets of washers and nuts on there, an 8mm, with standard nut and washer( black washers up against the prop driver) the others a 10mm for bigger wood props, just a guess,

there are two nuts Alan, but the larger sleeve nut isn't counterbored to screw down over the plain part of the crank so the prop hub would need to be more than 32mm thick - the wooden props I've got are nowhere near that.

alan cantwell wrote: The motive power is irrelavant, if it swings a prop, it works for me, but the laser is a thing of beuty, crafted from bar stock, no castings at all, from an engineering point of view, its a masterpiece of metal bashing

Just having a bit of fun Alan no harm meant. Dont tell anyone but ive got some electric models to :ohmy:

Geoff, my comment was not aimed at you, it was aimed at the usual detractor from all forms of power,

Rob, i had a look on the laser web site, baffles me too, the sleeve nut is looks like its drilled and tapped to accept a spinner bolt, but that aint reet good when the prop wont clamp, give Laser a bell, see what they are playing at

I'll drop Jon an email, he's pretty helpfull.
The immediate question is which way up to mount the engine -
Upright it will just about fit, but I will need to cut holes for the needles. I had pictured it mounted upright with no cutouts and remote needle assemblies but the carbs are 1/4" too high for that. Because of the offset to allow for downthrust it's going to be a tight fit getting the rocker covers in. However upright allows me to get some sound deadening extensions on the exhausts and I can get the tank within about 1 1/2" of the carbs, still low but apparently acceptable with a Laser.
Inverted the exhaust would exit straight out of the bottom of the cowl - though I miay be able to angle them enough - need to play more! The tank would end up about 2" above the carbs. At least it would self-prime
I'm guessing the supplied tank is about 16-18oz, should be enough, so I've drilled the bung for a second feed pipe.

One trick i have done with my laser installs, is secure a brass pipe into the airlfow, run it front to back, directly into the carb intake, seems to run better when its not picking up hot air from the firewall, i would also blank the HUGE hole off at the front, and have cooling air ducted over the cylinders, and out the bottom,

interesting idea on the carb Alan, it could be done with the gaps between dummy cylinders suitably ducted, central gap back to the carbs, gap each side to a cylinder each.
I need a 1" spacer between engine and bulkhead but this is upright (ignore the exhaust) and the top of the rockers is very close to the line of the cowl



or inverted there's more room for exhaust ducting than I first thought and more clearance for the rockers, plus the needles will be out of sight underneath:

either way, I've opened up the tank bay top and bottom, with extra liteply bracing to keep it rigid:

4 layers of 1/4" birch ply epoxied together and lovingly crafted into a mounting ring suitable for a Laser


Now i just hope I got my sums right for the bulkhead to prop-driver length :whistle:

seems a shame that the work of art a laser engine is should be covered up.my onl saito is on show in a red zephyr,now where is it stored

Can't be helped Steve, it's there to serve a purpose.
I looked out of the kitchen window this morning to see the trees bending in strong gusts, rain falling that looked on the verge of being snow and a generally unhealthy looking day so I elected not to go flying and get the engine installation sorted instead.
I have just discovered that I have no 5mm captive nuts. 4mm - yes. 6mm - yes again. Even 3mm, but not one 5mm so that bit of fettling will have to wait a couple of days.
Hey ho, maybe I'll start the tail end instead.