JRR
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[ame]https://youtube.com/watch?v=_uyvY0tDU4M[/ame]
Merlin V12
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JRR
Active Member
G'day Herbie
I bought all the castings and drawings from USA. I had it running 20 months later. Thanks for your nice comment.
I should have completed my address by adding Australia to it!
John
I bought all the castings and drawings from USA. I had it running 20 months later. Thanks for your nice comment.
I should have completed my address by adding Australia to it!
John
JRR,
My hat is off to anyone who has finished one of these. Your twenty month build time is really impressive. Are you using a spark ignition or glow plug? Is your supercharger functional and building boost? - Terry
My hat is off to anyone who has finished one of these. Your twenty month build time is really impressive. Are you using a spark ignition or glow plug? Is your supercharger functional and building boost? - Terry
JRR
Active Member
G' day Terry
I started building the oil pump first in March 2013 while waiting for the castings to arrive.It ran for the first time in November 2014. It is spark ignition and as for the supercharger it is turning at 30000 rpm but I cannot be sure if it is contributing any thing to the performance as I am not sure how to measure it, I suspect not much as it is too slow. I used the casting that was avaible for the crankshaft, that saved a bit of time.
I have to dismantle it soon to fix the water leaks from around the bottom of the sleeves and the last time I ran it , it passed a lot oil out from the exhaust pipes
I've had much enjoyment in that time but I am not expecting as much I this next phase!
John
I started building the oil pump first in March 2013 while waiting for the castings to arrive.It ran for the first time in November 2014. It is spark ignition and as for the supercharger it is turning at 30000 rpm but I cannot be sure if it is contributing any thing to the performance as I am not sure how to measure it, I suspect not much as it is too slow. I used the casting that was avaible for the crankshaft, that saved a bit of time.
I have to dismantle it soon to fix the water leaks from around the bottom of the sleeves and the last time I ran it , it passed a lot oil out from the exhaust pipes
I've had much enjoyment in that time but I am not expecting as much I this next phase!
John
JRR
Active Member
Terry I will try to down load some pictures
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Guess that's how it runs down under. 
JRR
Do you suspect the double o-ring seal design isn't adequate or do you recall any problems during fabrication? I'm concerned about all the coolant passages between the head and the cylinder block. Have you had leaks up there as well? Any tips or things you would have done differently if you were starting over? Thanks, - Terry
Do you suspect the double o-ring seal design isn't adequate or do you recall any problems during fabrication? I'm concerned about all the coolant passages between the head and the cylinder block. Have you had leaks up there as well? Any tips or things you would have done differently if you were starting over? Thanks, - Terry
JRR
Active Member
Greg, the compressor wheel or impeller is 3" in diam.
John
John
JRR
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Curious as to why prop speed matters on a model not mounted on an aircraft.
A 76mm radial flow compressor spinning 30,000 RPM will develop very little pressure. Compressor maps of the KKK K27 76mm compressor suggest it has a pressure ratio of 1.1 at 30kRPM and it's surge limit is 0.02m^3/s. At 3600 RPM flow through the engine is <0.013m^3/s so the compressor is very near the surge line for sure. The compressor might make ~0.1bar (1.5psi) of pressure.
Greg
Greg
JRR
Active Member
To satisfy your curiousity I need air flow through the radiator. A 3 blade prop would be the way to go but I have no information as how to build one.
I made a copy of the one I made for my 18 cyl Hodgson which moves a lot of air at 3000 rpm. It's diameter and pitch is 32" x 16". With the original gearing this only give me 1315rpm @ 3000. With the 40T/ 29T teeth I can get 2175 rpm.
Can you advise me as to what would be a suitable diameter and pitch for a 2 blade prop if I reinstall the original gearing?
John.
JRR
Active Member
r
I never held out much hope that a supercharger would serve any use at this size, I think it's only there so we can say " yes it has a supercharger" but it was interesting to make.
John
JRR,
Could you please tell me what you used for a carburetor? If I hadn't just completed the prop gear over the weekend I might have changed my reduction ratio. Do you think the overheating problem would be solved by a small electric fan blowing air through a small radiator tucked away under the engine? That's what I've been planning for mine when I get to that point. I think I read that some of the planes that used this engine had to have an auxiliary radiator (no fan) under the plane to control engine temperature during long idling times on the runway. - Terry
Could you please tell me what you used for a carburetor? If I hadn't just completed the prop gear over the weekend I might have changed my reduction ratio. Do you think the overheating problem would be solved by a small electric fan blowing air through a small radiator tucked away under the engine? That's what I've been planning for mine when I get to that point. I think I read that some of the planes that used this engine had to have an auxiliary radiator (no fan) under the plane to control engine temperature during long idling times on the runway. - Terry
JRR
Active Member
Yes , Wide open . How do you arrive at that figure? I'm out of my depth when it comes to the mathamatical part of this hobby.
John
