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Building Tips and technical articles. => 1/2 A building. => Topic started by: Larry Renger on September 20, 2011, 06:28:29 PM
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I reworked a Wen-Mac just to see what it could be if properly tweaked. The details will be in a coming issue of 1/2A Flyer, so get out there and subscribe!!! VD~
I have not run it yet, but I expect it to be respectable, possibly on the lines of the Atwood Shriek. More after some running. y1
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Next issue of "Half A Flyer" is due out by October 10.
Larry
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Larry,
A friend of mine had a very good running Wen-Mac engine, until the crankshaft launched it's front half with prop still attached. Man was that hard to find in the grass! ;D
I don't remember the model number of that engine, but I'm pretty sure it was not the first or last model built.
Inspection revealed what appeared to be an earlier crack at the crank intake port that may have been there for a long time. The edges of the fracture were clean and new most of the way around, but on one side was a very dark area presumed to be an earlier crack.
I'm sure you smoothed the intake port in your crank to minimize the tendency for stress cracks, but would like to hear how it goes with some run time.
Bill
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Looking forward to the article. In the early 60's I had a Scientific Gulfhawk ( the built up wing, profile version ) with a wen mac that I flew almost daily after work. I still have the motor, maybe I can rehab it.
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Hey Larry,did I plant a wen Mac seed a few months back when I asked you about the needle valve? THE Picture answered my question about using the head as a clamp for Merlin glowplug . T.J.
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Possibly,l but it is the obvious thing to do with any wee engine that sports a removable fin unit and a miserable regular glow plug. See my various posts regarding the Brodak Mk 1 engines. H^^
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Hey Larry , do you think a reworked Wen Mac would have enough guts to pull an S4 space kaydet around the OTS pattern? It might be fun to try and beat a Smoothie with a Wen Mac powered plane! I was thinking about a Man Win to see what it can do. T.J.
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If I get, say 15K on that 6x3, I would say it has enough power. I was going to run it yesterday, but my test stand won't accept the engine. I need to radial mount it on something.
I was able to run a Cub .099. After a huge amount of evil black crud cleared out, it ended up pretty good. Turned a 6x5 power prop at 11K. Even with whatever was grinding itself to bits inside, it finally ran with a clear exhaust and still seems to have good fits. I was running 10% Nitro, and suspect that going to 30% would make a huge difference (Cubs have rather low compression designed in, so they can handle the Nitro well) I have 3 more of these and plan to run them all and compare performance.
This was the engine specified for the Wee Duper Zilch. I have my doubts that it would work very well. I want to build that model for OTS and Leprechaun, but will power it with a PAW .061. That engine should turn a 7x5 somewhere around 12K.
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Hi Larry,
Neat project! The early Wen-Mac case actually had a bushing in the case for the crank, also look for Mk. II-IV (?) cylinders that don't have the groove that runs around the inside the cylinder. The ones that do, are good for about 1/2 doz. runs before there shot. Your right on the fuel, lots of oil and nitro...I wonder if a 5.5"x3" wouldn't give you a little more RPM without giving up too much pull?
take care,
Mark
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Ok I think I have settled on a baby barnstormer if the engine checks out ok.T.J.
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Possibly,l but it is the obvious thing to do with any wee engine that sports a removable fin unit and a miserable regular glow plug. See my various posts regarding the Brodak Mk 1 engines. H^^
Hi Larry,
I gotta get some kind of small lathe (and learn how to use it! LOL!!) to fix those heads for the Merlin plug................... along with other stuff like venturii! ;D
Big Bear
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Look at Harbor Freight. They have a very nice small lathe at a good price.
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Look at Harbor Freight. They have a very nice small lathe at a good price.
Hi Larry,
That is something I have thought about, but I need to get all the hospital bills, and finish the chemo therapy before I go buying a lathe. ;D
Bill
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OOOG! Good luck with all that! :P
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aaa larry. Did you ever fly an Aero-mite? LL~
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No, I owned one as a kid, but we moved and it got trashed before I ever got to try it. I still had the engine for a while, but don't know if I ever ran it. Later I had a Wen-Mac with the spring starter on a 1/2A Snapper that was silked. Not enough power, too much weight! :'(
When going through the pile of engine parts, there were a couple of the spring start jobs. I took one apart. The front housing is mostly solid 3/16" thick steel! A bit of lathe work would cut a huge amount of weight out of the engine.
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Hey Larry,
How do engine's like this Wen Mac compare to the run of the mill Cox babe Bee 049? I think I have one of these, a couple of Ok's and a pretty clean Holland Hornet 049... Might need to try and clean em up and put em on something. For the ones that might be missing a needle and spray bar, is there a good substitute?
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I have some of the old style wen macs like that one. I picked out one that felt the best and ran it. I got 14500 rpm with 20% nitro and a 5x3 prop. The steel fin wen mac are more powerful to me.
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The engine ran, but not well. Don't know why. Not as good as a couple of stock ones that John Wright has. It seems to have a drag in it somewhere.
The Steel fin Wen-Macs have Cox style bypass porting rather than the type used in old Atwoods. LeRoy and his gang knew what they were doing! Decent airflow and clean combustion chambers combined with incredible quality control. Wiped out ALL the competitive brands eventually. >:D
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Larry, im not sure but I think you can install a OK Cub cylinder right on that old style Wen Mac . If so you could use the type cylinder that uses the standard cox glow head. S?P
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I gave the engine to John Wright to play with. End of experiment.