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CriCri MC-15 in NZ

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MadRocketScientist

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May 16, 2009
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Canterbury, New Zealand, Earth, Milky Way Galaxy.
I am guessing under 1000 of actual building, I estimate I have averaged around an hour a day of building for the last year, hard to say exactly though. The CAD conversion of the plans has taken about the same amount of time,

I am strongly in favor of the ZDZ210B2 RV engines although I will most likely convert them to dual ignition.

Shannon.
 

litespeed

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May 21, 2008
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Sydney
ZDZ are a good engine and should prove good with twin ignition- the czechs really know their stuff.

So about 2000 hours including all the CAD and CNC?
 

Starman

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May 16, 2009
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High in the Andes Mountains
I'm looking at two stroke engines and prices now and the ZDZ engines look like contenders, I need two of them with at least 20hp each and 30hp is nicer, but the top two cylinder ZDZ engine has 22 hp so that looks pretty good. Which one are you going to use?

I'm curious about how you add dual ignition, does this also mean you also put dual spark plugs in the cylinder head? Is spark plug fouling a major two stroke concern like it was in the good old days?
 

MadRocketScientist

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Yes you put another spark plug in each head. I think two stroke plug fouling will always bee an issue. Larger aviation engines aren't two stroke and they also use dual ignition and plugs. When you are flying the less there is to ruin your day the better.

So about 2000 hours including all the CAD and CNC?
Possibly but I am hopeful that it will come in under that.

Shannon.
 

MadRocketScientist

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Canterbury, New Zealand, Earth, Milky Way Galaxy.
Recut the upper nose skin today, I misaligned it by 1mm when I first installed it and it has been giving me greif when trying to line things up. I also messed up the flange by stretching it too much and using a too big radius on the former when flanging it.

I CNC cut a new skin and former and the skin fits perfectly. I left out predrilling the holes that I had already drilled to 3/32 so that they would still line up when drilled in the skin. That means some of the holes are 1mm out of correct position. You will have to look close to spot them (I hope:gig:)

I have left a sharp edge on the former for the flanging. Preliminary testing seems to indicate that it won't need much of a radius to get the correct one on the flange. I will also take things a lot more carefully when forming the flange to avoid stretching the metal more than necessary.

The last pic shows the two formers on top of each other the top one has the radius on it. The new one seem to form the bend a lot better. I will know for sure once the flange is formed. The old skin would also be able to be used on another CriCri (if I build another) as the holes in it are still in the correct positions. The flange may be repairable.

Shannon.
 

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MadRocketScientist

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Canterbury, New Zealand, Earth, Milky Way Galaxy.
Formed the new flange in the upper skin, leaving a sharp edge on the MDF allows the metal to form its own radius. Much better than the first one. The flanging made the skin bow upwards so I used a hammer and dolly to stretch the flange somewhat. I takes a reasonable amount of time to get the flange just right with a lot of test fittings on the fuselage. I stretched mine too much (again:ermm:) so it will have an odd flute or two on the inside. The front skin is a lot better than it was and the cowl fits. Now all the holes in the fuselage frames line up like they are supposed too:).

Shannon
 

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MadRocketScientist

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Canterbury, New Zealand, Earth, Milky Way Galaxy.
Not much to report on build progress although I did manage to get a parts list in excel format completed. I have also cut a nose gear steering bracket (401 08-10) out of acrylic to test the concept and fit. The welded one was proving to be too hard to get aligned when welding. I will cut one out of 2024 once I have machined the excess metal from the nose gear tube.

Some pics of the test bracket.

Shannon.
 

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danmcgee

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Did not realize the administrator was across the pond, but now able to post. Great build log Shannon, I am following it with great anticipation of my own build and post my log here as well.

Dan
 

MadRocketScientist

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Cut out an MDF welding jig for my engine mounts on the CNC, I still need to drill the ends of the large tubes to fit the short bolt tubes. I 'could' have made something simpler but I have this machine:gig:

Shannon.
 

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danmcgee

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Shannon, you just keep comming up with these great ideas on how to do something simpler, and right the first time. You are saving me alot of time and effort when I start my build. Have someone on the hook now for the house so hopefully I can sell this one so I can get another down here were my new job is and get to my own building.

Great work Shannon, Great work.

Dan
 

revkev6

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massachusetts
I've been looking at two stroke engines to see what looks best to buy and I can't recall seeing any that have two plug heads. Of course reliability doesn't matter for PPGs.

the newer snowmobile engines used in arctic cats are dual plug. their 800cc twin cylinder fuel injected motor has proven EXTREMELY reliable in a sled. I know of a guy in alaska that has been looking to install one in a kitfox(I think) they make between 140-150hp at 7200rpm and rev up to about 9k rpm. peak torque is in the 5-7k rpm range. I think it would work great derated to similar RPM as a rotax.

btw, this motor uses a flawless batteryless EFI.
 

danmcgee

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Virgina/ USA
Hey Shannon, could you post some pics on how the wing spars are put together? I can't tell if the web is on both sides or if there is just an overlap of 2 webs inside. Or just e-mail me a e-drawing that has them broken out so I can understand the intent.

danmcgee40@gmail.com it can take up to 24 mb.

Thanks in advance.

Dan
 

danmcgee

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Ok maybe I have answered my own guestion here Shannon, let me know if I am right. Part 100-04 is a doubler only at the coneection end under the seat and extends only to the point of taper and part 100-03 runs the whole length of the spar to the wing tip.

Is that correct?

Dan
 

Starman

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High in the Andes Mountains
the newer snowmobile engines used in arctic cats are dual plug. their 800cc twin cylinder fuel injected motor has proven EXTREMELY reliable in a sled. I know of a guy in alaska that has been looking to install one in a kitfox(I think) they make between 140-150hp at 7200rpm and rev up to about 9k rpm. peak torque is in the 5-7k rpm range. I think it would work great derated to similar RPM as a rotax.

btw, this motor uses a flawless batteryless EFI.
That sounds pretty good, I'm off on another wild goose chase :)

Do you have any idea how much one of those units weighs or costs? New? From a wreck? I guess you don't get too many snowmobile wrecks compared to car wrecks :ponder:
 

revkev6

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massachusetts
That sounds pretty good, I'm off on another wild goose chase :)

Do you have any idea how much one of those units weighs or costs? New? From a wreck? I guess you don't get too many snowmobile wrecks compared to car wrecks :ponder:
You're talking about an off road vehicle that weighs about 500lbs has 150hp and travels on snow and ice exclusively, nahhhh they never wreck lol.

to be honest I haven't looked at the cost of them. they are relatively new, having come out in 2006 or 2007. If you came up with a complete used snowmobile that was in good shape, took what you wanted and parted out the rest you could probably make out ok. there is also a 1000cc version, but I'm not sure about it's reliability. It might very well be just as good as the 800.
 
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