Marty d's CH-701 build log

[Marty_d]

I bought the Unbrako 12.9 rated 35mm x M10 bolts for the other 3 mounting points (the big 110mm was in the engine - thanks for pointing that out M61!) plus a heap of 0.006" shim washers to pack between engine and ring mount.

 

I've put the engine on - good to see the plane sitting on its wheels without the tail end being propped up or suspended from the ceiling! - but haven't yet Loctited or torqued the engine bolts on.

 

This is because, while 3 of the bolts are accessible with a straight 8mm hex key on a socket mounting, the fourth one (top port) is shielded by the rear cylinder because, obviously, they're offset.

 

So I need to buy a long socket hex key with a ball head to put that one in, because I need to go in at an angle and clear the cylinder.

 

Do you think there's a shop in southern Tasmania that has one in stock?!

 

But anyway - here's some pics of her with the engine on.  That 3 degree offset is quite obvious when you look at the front end, but I did run a stringline from the fuselage centreline to the prop hub and it appears to end up in the middle.  (Thanks SketchUp!)

 

Heading out this afternoon to buy a bit of 3M type stuff to cover the instrument panel.  I was thinking a carbon fibre look.

 

 

 

 

[Marty_d]

First time I've had a chance to do anything on the plane today (blame my wife for wanting some fencing!)

 

As per the post about the water pump pipe position, I heated it up with a heat gun and used a dowel insert to gently turn the pipe. It worked fine (thanks for your advice everyone!) but guess what, even with the new angle there's bugger all clearance between the pipe and the engine mount - not enough for the thickness of the rubber tube that goes on it.

So after all that, it'll be an order to Bert Flood for an 85 degree one.

 

The only other thing I did was mount the Bing carbies and the conical air filters on the back of them.

 

Meanwhile, I got an email today from my mate Chris in Canberra - he's just finished his scratch-built 750. (He's not on this site). B&stard has only taken 2 years to do the whole thing!!

(My excuse is that his kids have grown up and left home. Mine are still very much underfoot!)

[kgwilson]

Apparently about half of the builds started never get finished. Usually a flurry of activity then dribs and drabs until nothing. Yours shows progress every time. I took about 2 years till 90% complete and the last 90% took another 2 1/2 years. Scratch building is a very satisfying experience. Some of the kits supplied these days are basically just assembly with almost everything pre bent, pre drilled and even wings complete & skinned etc. How they meet the 51% rule beats me. You don't build these, you just put them together. That last pic from 18 Dec bears a striking resemblance to a Ford T-bucket. (No offence intended)

[eightyknots]

Which aircraft did you build, KG?

[Marty_d]

That last pic from 18 Dec bears a striking resemblance to a Ford T-bucket. (No offence intended)

You're right, it does! (None taken).

[kgwilson]

Which aircraft did you build, KG?

The one in my Avatar.

[rgmwa]

Has anyone used the 912 with that setup (air filters straight off the carbs)? Most installations seem to use an airbox. Any advice either way? I'm not too concerned about the reputed 4% power gain from the airbox, a 100HP motor in a 701 has bags of power anyway.

 

In the RV-12 the filters are straight off the carb.

[kgwilson]

What do Rotax recommend? With a Jab 3300 an airbox feeding through a cobra head into the carb provides optimum airflow which is easily adjusted for each bank of cylinders. In your case you have a carb for each bank anyway so that negates that issue. Individual filters probably cost more but then you don't need an airbox. A Ryco A360 element costs $15.50 & I just replaced one after 100 hours. The original was still perfect but replacement is mandatory. Flying in a dusty environment like it has been out west will require replacement a lot more frequently.

[jetboy]

The airbox on the 912S is not just to run better it keeps the carbs from falling off

[Marty_d]

Ok, finally got a few hours down the shed this long weekend.

 

First, a pic of the carbies and air cleaners on. Bit confused about your post Jetboy - are you saying they'll vibrate themselves off?

 

 

 

Next - got stuck into the top window and windscreen - bit the bullet and cut the windscreen to shape.

I think it's worked pretty well - tight turn around the wing root corners but the people I bought the polycarb from said you can bend it as tight as you want.

 

The front aluminium fairing is 0.025" 6061-T6 which is why it has the cutouts to facilitate the curve. I have heard via IBob about someone in NZ who used a non-tempered alloy to form a fairing, but I thought I'd try with what I had and not too displeased with the result.

 

 

 

[onetrack]

Woo-Hoo! BIG photos! - and an engine and windscreen, both in position!! Is there spittle all over the inside of the windscreen, from you sitting in the LH seat and making, Vrrroom!, Vrrroom!, Vrrroom!, noises??

[Marty_d]

Woo-Hoo! BIG photos! - and an engine and windscreen, both in position!! Is there spittle all over the inside of the windscreen, from you sitting in the LH seat and making, Vrrroom!, Vrrroom!, Vrrroom!, noises??

Thanks!

 

No... I sat there and pretended I was in the circuit when I first installed seats and Y-stick. To be honest I didn't even sit in it today. Maybe I was worried it'd look like I'd wandered into IMC.

[jetboy]

• #410
  

Ok, finally got a few hours down the shed this long weekend.

 

First, a pic of the carbies and air cleaners on. Bit confused about your post Jetboy - are you saying they'll vibrate themselves off?

 

 

Yes Marty I have seen installations where the carb has fallen off, not once, not twice, but four times on the same engine and each time care was taken to fit the clamp correctly. Rotax have a few SBs out on this issue and supply a better clamp system now.

 

Then finally one of the club planes was doing touch & gos and just sputtered to a halt mid runway and had to be pushed off the strip - one of the carbs fell off. Especially prone with those pod filters, extra lockwire might be an answer. In the olden days with the 503 we went to the dual K&n filter so eack carb could hold the other on via the filter.

[bexrbetter]

 

First, a pic of the carbies and air cleaners on. Bit confused about your post Jetboy - are you saying they'll vibrate themselves off?

 

 

Firstly, great job Marty, although I didn't realise you were going straight to IFR flying, brave man.

 

I first trained as an Apprentice Motorcycle Mechanic in the 70s, and when I took a 'slip in' carby off like yours, I would just grab it and a couple of wiggles later it was out without loosening the clamp. For racing we would always run tie wire from the carbs to holes in the cylinder fins as a safety backup.

[Marty_d]

Did a bit on the instrument panel last night and today.

 

I will be pulling everything out again to paint/wrap (possibly after I pick up a radio) - but just wanted to see it all in place.

 

Will also get better M4 screws, possibly Allen head in black - these are just from Bunnings Aerospace for a test fit.

 

Talking of which - colours? I was thinking of a carbon fibre type wrap, but my wife said she thought white would be better. What do you folks have?

 

[IBob]

I've got a light gray, Marty. It's kinda traditional, but works for me.

[Kyle Communications]

Mine is hammertone grey...no glare seems to be fine...not sure I like bright colours on the dash but Bob's looks fine with the darker surround

[M61A1]

Mine is hammertone grey...no glare seems to be fine...not sure I like bright colours on the dash but Bob's looks fine with the darker surround

I got matte black. Great for when you’re on NVGs. Does get a bit warm though in Qld summer.

[Marty_d]

Thanks guys! That Sav one looks a lot taller than the 701 - plenty of space vertically.

 

Hmmm... light grey... matt finish... undercoat is light grey and matt! "Bridgewater Mist" as a work colleague poetically named it...

[Marty_d]

Mine is hammertone grey...no glare seems to be fine...not sure I like bright colours on the dash but Bob's looks fine with the darker surround

 

I like that hammertone Mark - how's that applied?

[Marty_d]

I got matte black. Great for when you’re on NVGs. Does get a bit warm though in Qld summer.

 

Why would you ever (legally) need NVG's in a recreational aircraft...?

[Kyle Communications]

The Hammertone I just did with a can of hammertone spraypaint

[Kyle Communications]

NVG..because he can :)

[M61A1]

undercoat is light grey and matt!

When I was at Amberley, it was known as "Ipswich Racing Grey".

[M61A1]

NVG..because he can :)

I wish....at $250k a pop for a Top Owl helmet, they'd get very upset if I borrowed on.....ITARS and all.