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About LohringMiller

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  • Birthday 03/05/1943

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    Eugene, OR

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  1. LohringMiller

    Esc overhead

    I run 8S on a stock Castle Phoenix 200 controller with water cooling. It works very well. I'm sure it could stand 300 amps without problems. Lohring Miller
  2. LohringMiller

    Engine observation and question

    I planned to make it a side exhaust engine, but the red coil would probably need to be repositioned. It could be rear exhaust. I will need an adapter plate because there's no way the Zenoah cylinder bolts will work. A square bolt pattern would allow side or rear exhaust positioning. The piston would need to be different for each. I also planned to use a 55 mm rod to give more room for the intake port. It's possible to run a boost port between the intake port sections. That might be even better if I can get enough area in all the ports. So far I draw a design, run the simulation and then redraw things to see what I can improve. Building something will be the real test but is a lot more time consuming. If you're talking about the FOS and sleeve valve engines, there are a couple of pictures below. Note the similarities. Both cylinders were designed to run on the same crankcase also pictured. I don't know how they worked but here's a video of the sleeve valve engine running. Lohring Miller
  3. We ran 2 5000 mah 4S packs in series for the two lap trials. Four 4S packs were used for heat racing. The Current NAMBA 1/8 scale rules only allow 6000 mah and 8S. That should be enough for a race with the propeller diameter rule limiting current. A race lasts less than 2 minutes so that's all the battery you need. I would consider 800 to 900 KV motors on 8S. The TP motor is available with this KV. The prop will determine run time. A smaller prop will run longer but slower than a 57 mm prop.
  4. LohringMiller

    Engine observation and question

    " Electricity has no soul. It'll be the death of motor sports. Might as well just play a video game. " I'm sure most horse owners felt that around 1900 about the IC engine. I think their argument was better since they're talking about animals vs machines. Here we're only talking about different machines. You obviously haven't driven an electric car or raced electric boats. I have an electric car and race electric boats. In the past I've raced both model and full size IC engine powered boats. Electrics now have higher performance than similar IC powered vehicles. Having said that, I'm working on an add on cylinder for Zenoahs. I would 3D print the model in a suitable plastic and investment cast it in aluminum. It's a fun project in pushing the limits. A steam powered RC SAW boat would be a similar project. I wouldn't expect either to be more than a fun hobby project to see what could be done with some old ideas. Lohring Miller
  5. LohringMiller

    Titanium Propellers

    That sounds like a good alloy. I picked tool steel because that's what I can harden easily. Air hardening tool steels don't change shape much with hardening either. I still think grinding after hardening would be good. My former partner, Mike Bontoft, used his CNC mill to grind a square on a Zenoah crankshaft . He had a 10,000 rpm spindle. At the time we tried making a propeller but had issues with my 3D modeling program and Gibbs Cam not working together. Keep on working on the props. It's one of the best areas for improvement. Jim Schaefer at ABC has been working with the electric racers on his latest designs. They are more efficient at converting engine power to thrust than earlier designs. However, his bronze alloys can't be thinned as much as steel alloys can. Titanium is great for corrosion resistance but that's not a problem in model boating. All you need to do is clean and apply oil after running. That's standard with our model's steel shafting. Really high performance props have been made with cast chrome cobalt alloys. Dental labs have been very accurately casting them with fancy vacuum melting equipment for decades. These days 3D printing is starting to replace casting, though. I believe cast chrome cobalt is the the prop alloy Joerg used for his close to 200 mph record runs. Some finishing is still needed, though. Lohring Miller
  6. LohringMiller

    Steps, Vents and Shingles

    Most outboard tunnels plane on their transom with the sponsons for stability in the turns. I wouldn't expect any help from shingles in the straights. Our SAW outboard tunnel ran more like a conventional hydro with the transom mostly out at high speeds. The heavy outboard still holds the transom down. Lohring Miller
  7. LohringMiller

    Engine observation and question

    I'm also an old fart who loves the sound of IC piston engines. I remember this and this from my youth and the sound of 1200 hp a few years ago. However I think the future of engines like these is around the same as piston steam engines in the 20th century. Steam still uses turbines and many large piston IC engines have also been replaced by turbines. Smaller piston engines are being replaced by electric motors. My lawn mower, leaf blower, and weedeater are now electric. The next generation will be battery powered. Inside the house there haven't been IC engines for a long time. The king of modern two stroke scavengine is the Aprilia 125. Most engine developers use variations on that 5 transfer design. It's possible to shape the power curve with variations on the port angles using the right pipe. A newer scheme, I call the FOS system, uses 360 degree exhaust porting over 360 degree transfers. This should allow much better breathing at high rpm. Earlier attempts were the Rolls Royce Crecy that used a sleeve valve to get a similar result. The difference is the scavenging pattern. The FOS design forces a loop pattern that results in a rising central column that loops at the head to flow down the cylinder wall and out the exhaust. The Crecy system may leave some of the cylinder unscavenged without careful intake port design. The limitations were mechanical in the Crecy and might also be mechanical in smaller engines. A motorcycle size sleeve valve two stroke has been built, but I haven't heard how well it worked. I believe it's waiting on a pipe design. He has also built a FOS style cylinder for the same crankcase. Below are some drawings of the FOS system. Lohring Miller
  8. LohringMiller

    Titanium Propellers

    What 3D modeling program are you using? I've been doing parametric propeller designs in Fusion 360. So far I can model propellers with the number of blades, pitch, rake, cup, blade thickness, blade area, and hub size as variables. Progressive pitch would be my next step. My plan was to 3D print the pattern and investment cast it. However, machining the prop should allow thinner blades. You would need to support one side with a low melting alloy while machining the other side. Grinding should work even better. Material strength is what allows thinner blades. I would consider an air hardening tool steel for SAW props. We ran knife blade rudders with a considerable speed improvement over aluminum rudders. A long time ago I built a jig to machine propellers on a conventional mill. It used tracing on a sheet metal pattern to get the blade shape. It gets clamped in the milling vise at an angle to generate rake. I haven't used it to actually make a propeller, but it was a good exercise in understanding propeller geometry. Lohrig Miller
  9. LohringMiller

    Steps, Vents and Shingles

    The goal of these efforts is to reduce contact with the water to reduce drag. Stability in monos and especially tunnels is also an issue. I believe the old Prather tunnel needed its step for stability in turns. Our attempts on reducing water contact were air traps. We used air trap sponsons on all our later gas hydros. It was one of Mike's off the wall ideas that added 2 to 3 mph over conventional sponsons at 100+mph when we bolted a set on. They seem to be at their best with heavy boats. I've tried them on a P limited rigger with mixed results. A non trip is needed for heat racing boats.
  10. LohringMiller

    Engine observation and question

    The American model engine makers often built engines as a sideline to their main business. Also, after World War II there was a huge interest in model airplanes. That made a much larger market for engines than exists today. If you think of the nitro engine as one of several ways to power a vehicle, more modern power plants have taken over. Small model boats and airplanes are being increasingly powered with electric motors. Larger models use industrial style gasoline engines. Both are mass produced for many other uses, keeping costs down. The change I see is increasing use of electric power as battery and ESC costs keep coming down. Already 7.5 cc size boats can be powered with a 6S battery power plant at a cost similar to a nitro engine and its fuel. Smaller electric models are already less expensive. This is only going to continue. Lohring Miller
  11. LohringMiller

    Engine observation and question

    The secret, especially in larger engines, is scavenging and breathing. The secret at the model level is friction reduction, especially in the piston and liner fit. As you scale down an engine the power producing displacement decreases as the cube of the scale. Surface areas decrease as the square of the scale, a much slower reduction. That scaling helps a lot with port and heat dissipating areas, but not with friction. Friction losses depend to some degree on the surface areas of the rubbing parts, a larger fraction of the displacement in model engines. Larger two strokes' rpm is usually limited by breathing, but model engine rpm is often limited by inertia and the rod big end bearing. Scavenging plays a part, but isn't as critical. The best scavenging comparison I have is the difference between the M&D modified Zenoah cylinder and their cast cylinder. Both are nearly identical except in the transfer passages. The cast cylinder doesn't have an ideal shape, but does have an inner wall. Quickdraws have even better scavenging but may be limited by their piston port intake. Tuned pipes have the biggest influence on scavenging compared to all these other factors. For that reason, I bet relatively poor transfer shapes can be overcome with carefully fitted ABC or AAC piston and liner construction and the right pipe for the application. Lohring Miller
  12. I wrote an article on nitro to electric conversion. The boat still holds the NAMBA 1/8 scale and T hydro two lap records. See http://namba.com/content/library/propwash/2012/November/#/18/ Lohring Miller
  13. LohringMiller

    Engine observation and question

    Almost all the American innovators in model engine design are long gone. Quickdraw are the only people I can think of these days. The only new developments in larger modern two strokes involve fuel injection, mostly to control emissions. Except for model cars, power in models has gone to low cost, industrial style, gasoline engines and electric motors. Unless you have a source for low cost manufacturing, I wouldn't expect anything new at the model level. Jim has pretty much covered where the state of the art has been for years. Lohring Miller
  14. LohringMiller

    NAMBA and IMPBA Hall of Fame

    One of the criteria for inclusion in the NAMBA hall of fame is contributing to the hobby including making boats and parts. Quite a few members have built well known hulls. Length of membership in NAMBA and positions held at the regional and national levels are other factors. Lohring Miller
  15. LohringMiller

    Carbon-carbon Pistons

    I keep thinking that carbon epoxy engine blocks might be possible. You would need metal for the working parts. Heat is the major issue. Even high temp epoxies are only good to around 600 degrees. Brian Buaas has been building carbon epoxy tuned pipes for nitro engines. Maybe that experience could be valuable. Lohring Miller