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McCulloch 32cc on a 85" 14.5lb Extra 330?

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Old 05-12-2006, 04:10 AM
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rangerfredbob
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Default McCulloch 32cc on a 85" 14.5lb Extra 330?

it's a KMP model I got for free that needs a bit of work and all hardware and stuff, and I have a McCulloch 32cc sitting around, here's the specs on the plane that I know (about all I know about it)

Weight :16.6 lbs
Fuselage length 78.5 inches
Wing Span 85 inches
Area 1424 sq. inches
Engine 3W-50cc, G-62, MVVS 58cc

the engines it lists are supposed to do 3D, which I'm not worried about as I just solo'd not too long ago... I've seen that the McCulloch's are supposed to be torqy and there's a bit out there on moding them, but I figured I'd ask those with more experience than those I know, but we're also planning on putting a Ryobi 31cc on a 60 something inch Cap 232... man that was a fairly simple conversion

btw, do the 28 and 32 have the same cranks? I have two 28's and the 32, if a 28 would fly the thing I'd almost rather use one of them, the 32 is on a nicer trimmer... but if the parts could be put on a 28 and be the same, that would work too. if this doesn't work, I'll keep looking for something in the 40's I guess...

Thoughts? opinions?

Thanks! getting excited...
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Old 05-15-2006, 12:47 AM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

no one has any opinions? I have the 32 stripped down to 4.5 pounds without trimming the flywheel or head yet.

I'd just like opinions on whether this engine will fly the plane and do basic things like loops and rolls and stuff, and anyone with experience with this engine conversion with specific tips on what's best or if I will need to modify the ports and stuff to fly like I'd like to, if it'd do that without modification I'd rather try it that way before messing with it...
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Old 05-15-2006, 04:24 AM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

I have one of these too, and would like to know more about these engines.
Scott said he has build a few of these. They ran good but were a little heavy.
But I'd like more info. on this engine.
By the way, I don't know which one I have. The 28 or the 32cc version.
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Old 05-15-2006, 09:44 AM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

It should fly, but its about 4lb to heavy. You will have around 12lb thrust. See if you can run down a Poulan 46 engine. It would make the plane more interesting.
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Old 05-15-2006, 01:02 PM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

I've got a Homelite chainsaw I could strip down, as far as I know it only needs a helicoil in the spark plug hole to get running... I should check what size it is. it is old though, so it might not be worth it

to see what size the McCulloch is, take off the muffler, it says the engine size right under the exhaust port on the head...

actully, this engine is right at the weight of a fully equipt Fuji 50cc (and should be after sheding weight and adding the prop adapter), so it could end up being closer to 16 pounds. before flight I'll turn the flywheel and possibly chuck the head in a lathe and get rid of some of it's fins, and some more trimming on the mag mount plate. I'll still be on the lookout for bigger engines, but this is what I got for now...
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Old 05-15-2006, 04:54 PM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

You said the airplane is designed for:

Engine 3W-50cc, G-62, MVVS 58cc
A 32cc engine is about half the displacement the design suggests. A half size engine is likely to be less than adequate.

Bill
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Old 05-15-2006, 06:58 PM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

yeah, but it's also supposed to hover and stuff with those, that's a long way off for me, and I can't afford the $450 price tag on most of them...

like I said, I'll keep my eyes open for deals on bigger engines, but if this one gets it off the ground and can cruise around I'd be happy for now...
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Old 06-03-2006, 03:01 AM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

it might change some opinions, but I did the math earlier today and give the plane a 14.5 pound RTF weight, unless all of the radio gear and fuel tank and stuff is more than 2 pounds... the bare plane with wings, tail, landing gear and cowl added to the engine that isn't done with it's diet all adds up to 12.5 pounds (including a bit to account for prop and adapter)

things it still needs to be ready to fly is a complete radio system, fuel tank, linkages, tires (main and tail, going with 4-6" pnumatic), little bit of paint on the cowl, and monocote to cover the bottom of the plane. we added up all of the components of a radio system and came up with just less than a pound, and figure about a pound for the rest, so that puts it at about 14.5 pounds
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Old 06-03-2006, 10:00 AM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

At 14.5lb things are much better. About all you can do is, do it and see if the way it flys works for you.
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Old 06-03-2006, 10:04 AM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

that's the plan, do it up with the engine stock, then modify it from there if needed, I've got a very experienced engine modifier that's pretty willing to help... first I'm going to try to chuck the jug into a lathe and turn it down some and other stuff with the block...
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Old 06-03-2006, 01:07 PM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

You can get more power out of the McCulloch if you convert it to gas/glow hybrid and use an APC 18x6W prop, you can also shed an extra pound off by eliminating the heavy flywheel and coil, I suggest that you replace the original heavy muffler for an aluminum one, if the plane is at 14.5 pounds it should fly good with the Mac converted to GAS/GLOW hybrid
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Old 06-04-2006, 09:24 PM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

I'm going to try regualr fuel mix first, going for budget and ease, and I just want to do that for now... might convert later.

I do have another question, what would be a good way to make the firewall? I didn't see the plane when it was put together before and don't have the instructions and don't have that much experience with planes yet, especially this size (my only other planes are 40 size nitro), the way I got the plane was with two sides with two laminated pieces of 1/8" ply and one piece of the 1/8" ply on the bottom, this has the side thrust built in, the bottom corners have basswood triangle stock. what I've done so far is made two plates of some 1/8" ply I have and glued them together then epoxied those in the plane. I bent and cut up some sheet metal into L brackets thinking of putting 6 of them on, two on each side and two on the bottom and using 6-32 nuts and screws, and epoxiing some balsa triangle stock between the brackets, does that sound ok? I'll try to get pics later... what should I do about the top? I was thinking just screwing down a piece of 1/8" ply to make an access pannel to the front part like fuel lines and stuff would be decent, but wanted to know if I should make it solid for structure...
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Old 06-04-2006, 10:19 PM
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Default RE: McCulloch 32cc on a 85" 17lb Extra 330?

ok, hopefully these show what I was talking about with the firewall earlier better than the text...
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Old 06-05-2006, 01:38 PM
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Default RE: McCulloch 32cc on a 85" 14.5lb Extra 330?

I realize I'm not a photographer, but any opinions on the firewall would be appreciated, I've looked around for pictures online, but haven't found anything all that helpful, and no pics of anything with firewall's like this, from what I saw when I was researching the plane it came with some aluminum angle stock that was apparently bolted to the sides and bolted to the firewall, which is kinda where I was going with the sheet metal (I know it probably looks flimsy, but I was going to put the bolts very close to the bend, it'll be sturdy, plus they're epoxied in place), and I was going to put the angle stock between the pieces too, that seems sturdy to me, but I'm not that experienced in modeling... especially not this size

all of the epoxy I've used has been 30 minute, so it's nice and tough...
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Old 06-05-2006, 02:36 PM
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Default RE: McCulloch 32cc on a 85" 14.5lb Extra 330?

Instead of using sheet metal, how about metal door screen?

It's light easy to work with. The epoxy will go right through it.
It should be as strong as 22 gauge sheet metal, easier to work with and lighter.

Just a thought
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Old 06-08-2006, 03:31 AM
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Default RE: McCulloch 32cc on a 85" 14.5lb Extra 330?

ok, conversion of the engine is about done, other than mounting the engine to the firewall and getting a RC plug and balancing the flywheel... machined out the prop adapter today and cut down the cooling fins about where I want them (basically made them round). the engine complete with prop adapter (minus prop and bolt) with carb, muffler and flywheel comes to about 4.3 pounds, add 3 for the fuse, 3.5 for wings and tail and a couple more for radio and other assorted hardware and you get somewhere around 13 pounds, I think the prop adapter ended up lighter than I expected, it'll probably end up closer to 14 lbs when all is said and done, but whatever... still better than I first thought

I think I'm going to fiberglass the firewall just to be sure, after putting the screws in and adding the triangle stock... overkill is always better. I'll figure out the final firewall ideas after the holes are drilled for the engine mount...
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Old 03-31-2019, 06:05 AM
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So did it fly?
If you kept it at 14 lb, it would have a CWL (cubic wing loading) of 7.2 which is light. Anything under a CWL of 7 is a floater
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Old 03-31-2019, 09:37 AM
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I had a few of these trimmer engines,and if I remember right you could take off the flywheel and remove the three screws holding the plate that has the ignition module on it and loose a little weight. You could then use an electronic ignition and find an aluminum muffler and have a pretty small and light engine.Here's a 28cc that had the plate and ignition module removed.I would have went with an electronic ignition and an aluminum muffler if I would have kept it.


Last edited by Tidnab; 03-31-2019 at 10:04 AM.
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