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Marty d's CH-701 build log


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No Hank...they are super thin and if they were hard alu lines them maybe ok but you have a lot of vibrations in and around the engine....I dont know Hank it just doesnt sit right with my brain about using that...give me the correct rubber style lined reinforced hose any day..also for ICP its a way or further reducing build weight too

 

ICP still quotes the empty weight of a Savannah S to be 286 kg plus or minus 10%. In other words, a range of 257.4 kg to 314.6 kg. See the picture of the official plaque for my plane.

 

The 286 kg mass is close to the Zenith CH701 planes the earlier Savannahs were derived from.

 

I have never heard of anyone completing a Savannah S at 257.4 kg: not even the unpainted, fixed seat, two-tank, non-extended baggage variant fitted with an 80 hp Rotax as they have in Europe. I have heard of quite a number of people completing their Savannah S around the upper end of the range of 314.6 kg.

 

Perhaps these fuel lines are on of ICP's measures to reduce weight closer to the more realistic officially quoted weight?

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Marty Glassing is easy..just messy. Must get all the air out of the weave thats all so use the ribbed rollers. You probably need to cut some 10mm ply and cut out to match the curves on the outside the

It's been a while...   Fortunately @wideblueyonder just lent me some cowl moulds, so this is inspiring me to get back into it.   I bolted the engine back on temporarily to test fit

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So try #2... got the jig made up today and strapped the muffler to it. (Upside down, obviously, in the photo below). Screwed the outlet stubs to their equivalent positions.

Also made up a protractor to help with cutting the angles in the donuts.

 

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  • 3 weeks later...

Hey folks,

 

I need some advice... again...

 

The muffler pipes are all cut out and assembled on the jig ready for welding (dropped it off to the welder yesterday).

 

BUT I told him to hold off on welding the exhaust pipe to the muffler until I got some advice.

 

Firstly - it IS welded, isn't it? I've seen some installations with a longer stub coming out of the muffler that the exhaust pushes over and is clamped with hose clamp and held on with springs. But my muffler has the short stub, no spring holders, and the exhaust pipe is the same diameter as the stub so no way it's going over it.

 

Secondly - the angle. I've tried to look at as many 701 pics as possible but they're good at hiding the exhaust. I've seen a couple which seem to show the exhaust coming back under the firewall at a fairly shallow angle, I reckon about 30 degrees or less from horizontal.

 

I think where mine is mounted I may even be able to get 20 degrees or less, as shown below. Question is - is it better to have it angled that far?

 

Thanks!

 

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Well your muffler has lugs on it that appear to take springs. My Jab 3.3 muffler is just a push in fit for all 6 pipes and 2 springs per side. That makes it easy to remove when required and it has never leaked, moved or vibrated when assembled

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Well your muffler has lugs on it that appear to take springs. My Jab 3.3 muffler is just a push in fit for all 6 pipes and 2 springs per side. That makes it easy to remove when required and it has never leaked, moved or vibrated when assembled

 

It has lugs for the pipes from the exhaust ports in the engine, but it doesn't have lugs for the actual exhaust pipe.

 

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I see. My exhaust pipe is welded on to the muffler. It is straight so that makes it easier and also the cabin heat jacket fits around that pipe so if the exhaust was clamped there is the possibility of carbon monoxide leaking in to the cabin via the cabin heater.

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I decided to box up the engine until the plane's painted - almost finished whipping up the box this morning. I've also ordered a couple of electric pet blankets (about 20w, 12v with transformer) - one for under the engine and the other one for under our new puppy which will be coming home in 3 weeks!

 

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I'm surprised you didn't get more informed thoughts on your tailpipe attachment.

The only comment I would make is that in a hard climb or a steep approach, the airflow round the cowl is quite different than when in cruise. (In the Sav what I see is rising airbox temperature, which indicates that the the airbox is taking significant air from under the cowl, instead of via the naca scoop on the top.) I would expect that exhaust fumes would also take a quite different route in those modes, and to be aware of that when positioning the tailpipe.

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  • 2 months later...

It's been a while...

 

Fortunately @wideblueyonder just lent me some cowl moulds, so this is inspiring me to get back into it.

 

I bolted the engine back on temporarily to test fit the mould.  I got some advice from the Fibreglass Shop in Hobart that the moulds are too thin and need beefing up, so the first job (while on the plane to maintain shape) will be to add wooden strips and fibreglass them on to the outsides of the moulds.  After that will be some more smoothing to the insides (surfboard filler epoxy was suggested, with sanding down to 1500 grit), then on to making the cowls.

I've never fibreglassed anything before, so hopefully beefing up the moulds will be good practise, and as always - if you have any advice gained from experience, please tell me!

 

 

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Marty Glassing is easy..just messy. Must get all the air out of the weave thats all so use the ribbed rollers. You probably need to cut some 10mm ply and cut out to match the curves on the outside then glass those onto the outside of the cowls to make them hold their shape..then your good to go. A tip though is to make those supports all level so you can lay the mold on them and they are solid on the ground as you layup the glass. The only other thingis good canuba way first and many coats then spar on your release agaent then go to town glassing and make sure you squeeze as much loose resin out of the weave. Have a look at Mike Patey's Youtube channel...carbon fibre and normal glass there is really no difference in the way he does his layup..although he prepregs everything because he can but the old way is fine with a brush

 

 

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  • 1 month later...

Got the welded up exhaust tubes back from the welder a couple of weeks ago, only just got an hour to test fit.  I also bought a threaded stud and 8 new lock nuts from Bert Flood, but for this fit just used the original nuts.

 

It's gone on mostly ok but the ball of one of the long pipes is not quite seating.  Not sure whether to get the welder to cut and insert a very short length to make it a bit longer - any advice??

 

Sorry about the darkness of the photo - need some more light in the shed!

 

Firstmount.jpg

 

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Having a stab at a fix, and depending on how short it is, say 6mm.  You could consider cutting the pipe. Then fit the pipe back on with the ends located, into head and muffler. With a gap presented you could steel epoxy some steel rod ( serious, No laughing) to just under 180 degrees around the pipes, like a splint and also tie wire around them to hold in place.  Then you can remove and have your welder slide in an insert and weld it half way round.  Then remove the steel epoxy and rods, clean and prep and weld that bit.  It is like being held in a jig.  I say this because it seems your taking the job to the welder not doing it in sitsu.

 

other wise you may need to have the one pipe sliding adjustable and clamp at it’s correct length.

 

the pipes need to be perfect length for a solid firm fit.

 

disregard if you get a better suggestion.

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