Discussion in 'The light stuff area' started by MadRocketScientist, Jun 19, 2009.
It looks great with both those engines mounted.
First up, a picture of the instrument panel as it stands.
I finally got my airspeed indicator. Aircraft spruce has recently put the prices of the swift airspeed indicators up but there were a couple that were the old price listed on the website. I picked up the 200Kt one for the old price but this has since increased. I think they might have forgotten to change the price. Anyway its here now!
I purchased the voltmeter to the left on Ebay, I have them in green, red and blue. I may go with the green yet. The
And secondly a short video testing the starter on the mounted engine.
Add fuel! Add fuel!
I had better attache the tuned pipe first or the neighbors wont like the noise
Today I made a nut... out of 2024.
The elevator pushrod has an adjustment with a locknut. On careful reading the plans this nut is made from 2024 aluminium. I made it on the CNC and the lathe and threaded it 1/4-28. Saves 3 grams over the steel nut.
The pictures tell the story.
Interesting thing I read recently about the Alodine 1201 that I didn't understand earlier. The 1201 is mixed so that it can alodine parts in the field and is designed to be brushed or dabbed onto the aluminium. To use it as a bath it needs to be thinned down 1 part Alodine to 2 parts distilled water. That explains all the 'fun' I was having trying to get an even finish on my parts without them going really dark and powdery in places. I really would prefer to be able to get the powder and mix my own but it seems to be next to impossible to buy here in NZ.
Purchased some 1/4-28 bolts today for testing with. They aren't the final bolts I will use for flying but I can now fit the club props to the new prop hubs. I put some of the bolts in the engines so the propellers are actually held on. There is still a list of things to do before I run an engine on the plane.
Making progress on the elevator setup.
Interestingly the amount of stick travel shown on the plans is more than needed to get the correct amount of elevator movement. The plans shows that the stick limits should be 28° forward and 20° aft (neutral is 5° forwards). I only need to have the limits at 25.5° forward and 17.5° aft to have the actual elevator travel of -9° and +4°. So 2.5° less each way. I was struggling to get more than the 17.5° rearward due to the stick contacting the spar box and the controls start binding past the 25° or so forwards. Thankfully it seems the plans measurements are slightly out and I have a large enough range of movement.
From vague memory I think Wayne had the same issues when building ZK-CRI, and ended up with extra elevator travel after adjusting the stick limits as per plans. However his website is no longer available, I guess I could see if it is on waywaybackmachine to check.
El cheapo angle gauge from ebay, seems to work okay but a bit slow to refresh.
A day or two ago I cut some more foam strips to make the stiffeners for in front of the spar box. Normally these hold apart the air vents on the floor but I am thinking of having the fresh air vent/s elsewhere instead. I will stick these stiffeners in place anyhow.
I sliced some of the divinycell down to 12x8mm.
Then glued on the 0.020" cap strips.
And eventually cut them to shape to fit into the lower fuselage.
Since I had the MIG welder out I started welding up the two halves for the expansion chamber for the exhaust. The welding is pretty rough
I can almost guarantee that water will leak somewhere and have to be rewelded! The metal is 0.6mm thick and I haven't done much MIG welding for ages. The waterblaster at work is being borrowed for the weekend so the earliest I can sort out the hose fittings and test this will be next week sometime.
I needed to make sure that the locking clip for the wing pin would also clear the stiffeners. That was when I remembered that the wing pin handles were hitting on the side frames of the spar box when fully inserted. I picked this up years ago but hadn't done anything about it.
I got out the torch and heated the wing pin handles and bent it up some more where the handles enter the wing pins. I then straitened out the Z bend in the handle.
Then I heated the handle slightly closer to the wing pin and bent it parallel to the rest of the handle.
I found a piece af aluminium the right width the check the Z bend.
Re-bent handles. I think I prefer to bend these handles cold and when they are still attached to the longer piece of tube. However heating them up did help me to recover this slight mistake.
I think everything is going to fit just fine.
Last picture from inside ZK-LBW, it seems the wing pin locking clip was made slightly differently to the plans but came in handy as a comparison.
Looks cool MadRocketScientist !
How wide is the wing ( chord ) in Cri Cri ?
4900mm span, 626mm chord (wing + flapperon) 480mm chord for the wing alone. Mine will have a little less span due to the non standard wingtips.
Awesome 480 mm main wing.
I asked around for a pipe fitting for on the expansion chamber and found a short bit of water pipe. I welded it onto the chamber and after a few rounds of hunting the leaks, I partially inflated it with the hose. Looking forward to Monday for a better attempt with the 2000psi waterblaster. 60psi made a good start.
do you get all the air out? I think a grease gun puts out more pressure.
"A high-pressure grease gun delivers pressure up to 15,000 psi. " Google
if you need that much. that is a lot of grease to fill up your pipe.
Fill it with kerosene. If there is a hole, it will find it. Pressurized that much and it might hurt someone.
Yes I filled it with water first! I intend to live a bit longer... I did think about the grease gun but as soon as it springs a leak I couldn't pump it fast enough to keep up any sort of pressure. Some use an old grease gun submerged in water for poor mans hydroforming. I will see how things go with the 2000psi waterblaster and go from there.
Hydroforming with a pressure washer? Been taking lessons from Furze?
He is one among many... yes
For angle adjustment on my 3 blade prop I downloaded an inclinonmeter onto my phone. Free app and works accurately enough on a 500 mph tip speed.
Just a thought.
I have a friend who did the same thing for the flying surfaces on his piper cub.
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