I'm glad that I saw one engine work correctly the first time rather than sputter and stall half a dozen times like the original ones seem to do in the videos. This one is new, so that makes sense. The other original demonstrators must be all out of tune and not synchronized correctly. This is the way it is supposed to work. Thank you. Aarre
These are dry-sump engines, oil is kept in an oil tank. A scavenging pump draws oil from the engine, and pumps it to the tank. The oil pump that lubricates the engine draws from the tank. Some oil does seep past the rings on lower cylinders, which causes the traditional smoky-start of radials. Radials are generally turned several blades by hand before starting, to assure there's not enough oil in lower cylinders to cause a hydraulic lock, which could be very damaging to the engine.
A remarkable engine, a radial that gets 150 horsepower from a 3.6 liter displacement; back during World War II, radials of similar horsepower output had displacements of 7.2 liters or more (and were much heavier). I hope Rotec considers building higher-output engines in the future, as a 5 or 7 liter radial engine would be ideal for replacing the older radials in classic (or replica) cabin-class airplanes.
It was a total mystery to me how the valve timing in these engines worked... until I found the old Spirograph I played with when I was a kid. That unlocked the whole secret.
I can't believe you would take a perfectly good George Benson soundtrack and contaminate that great musical masterpiece with a CNC radial engine build.
A life time of playing with engines led to this realization of this project. Prototyped in 1999 and still in production today. Over 500 units sold. Its a geared engine with 3:2 planetary reduction. Cost around $22k usd.
Radials, what cool lookin' engines. Too bad Jacob's Aircraft isn't in my backyard anymore. I live in Pottstown PA., so they would have been just a few blocks from my place. They used to make the Shakey Jakes. My Dad said that he used to play around in their scrapyard.
The fuel pump, like with any engine just keeps the carburetor full of petrol. The carburetor then feeds the centre of the common intake plenum chamber. Within this chamber is a simple mixture distribution fan that spins at engine speed and its main purpose is to sling the fuel/air mixture evenly to all cylinders. You see with a radial engine some cylinders are low and some are high so the low ones would run rich and the high cylinders would run lean without the fan, which evens things out.
wow. amazing! I always think propellers are attached according to their number of cylinders arranged but in this video I can see only opposed type propeller with many cylinders. But it's still working which is so amazing
+smith thomas You mean a two-bladed prop? The propeller's static power absorption is determined by it's diameter, not just the number of blades. The prop is matched to the engine's power output at a given RPM, it's not just the number of blades versus the number of cylinders.
+nutnfan1 At the crankshaft speeds of direct-drive airplane engines, 4 valves per cylinder probably isn't needed. The volumetric efficiency is high enough at the speeds propellers run at. WW2 engines (Merlin for example) were geared to run at higher RPM than the prop to allow higher power output; for their bore and stroke, 4 valves were useful for these big cylinders to inhale more charge in less time (higher RPM) and produce more power. It's not needed on small bore & stroke civilian aircraft engines that run at moderate speeds and are intended for long life.
Cool process, it inspires me to build a 1/2-scale human-operated B24 or B25. Since it only needs to carry a pilot & maybe a passenger, 150 x 2 would be perfect for a cool twin-engine ride!
+John Benton Not quite, unless you consider 'ideal' to be as expensive as possible :) These powerplants certainly do run and are useful, but for this power level much simpler, less expensive examples will produce the same power while burning less fuel. These are 'nice-to-haves' moreso than being an ideal solution for small aircraft propulsion. At 150HP a four cylinder is more like it, six if you want something really fancy :)
There has to be more to engineering design and execution than simple economy. It's why I get up every day - in the hope of finding something unusual! My dream is to design and make a radial engine with OHCs. I stopped when I realised the amount of gearing involved.
Here is some good advise, ROTEC : Make the 3500CC concept model, a production engine for model airplane enthusiasts ! 1/4 scale aircraft are huge on the market. I myself would like to see one in action.
Hi, I'm bluiding my own engine. Can you tell me out off what kind of material the cilinders sleeves are made off? (specs) and what kind of heat treatment? Thanks
Actually, some of us came here to be educated and NOT listen to music. We could stand in an elevator for that. These guys have so much knowledge and have done so much hard work and they tell us nothing? This is a rather horrible format! Thanks for the effort and best of luck.
They just want to show us how cool they are, with a horrible interlaced video. Clearly as you can see, there is no place or room for the man testing the engine at the end of the video. Not even safety measurements for the poor guy.
If you knew what you were looking at, you should know the work and engineering that goes into making such an engine. The music reminds us that we're not (or shouldn't be) at work while watching work being done.
Superb! Nothing beats a hand built item, no matter what the item. . Woah! I hope that trailer is pinned to the ground. Otherwise there's gonna be a whole lot of grass cutting going on at very high speed!
My perception is that one con rod & it's big end run on the crank & the daughter con rods are effectively connected to that one rod, not directly onto the crank.It's not very beautiful, but it's very effective.....not sure it's well balanced or can be balanced well, but it's worked well enough for over a centuary.
The engine's own weight, it is mounted aft of the fulcrum created by the trailer's axles. It's also using a test stand propeller the pitch and twist is enough to get air over the cylinder heads to cool the engine but doesn't give it much thrust in a rearward vector while supplying a load for the engine.
I was wondering that too. Looks like a regular propeller to me, and would rotate it over the bricks if not secured at the trailer hitch. Maybe a stake at the hitch?
I didn't see anything related to the lubrication system (drilling the crank, oil pump, etc) on this video. But I assume it must have a dry sump system. I wonder if it uses as much oil per hour as most old radials.
wow thts really cool. I like how they basicly showed the construction f it from begining to end. just out of curiosity what would an engine that small fit on? like a little single engine or something? still really cool. I always have loved radials. even tho they are kinda dead. i like how they fit togeather so perfectly almost like a turbine really impressive :)
That is a good point. I remember seeing an experimental aircraft that had an all aluminum big block v8 mounted inverted with a dry sump oil system & gear box. If i remember it had a 6 bladed carbon fiber prop. The tail number was "420HP" as it was putting out 420hp. It sounded like a nitro drag car on take off! Sorry I didn't mean to sound like a jerk with my comment.
@delgaraulito Yeah, we worry more about reliability and so the compression ratios in aircraft engines are much lower than in cars. Ratios of 7:1 as opposed to 15:1 like in cars produce less power, but let the engine last longer between overhauls.
Benson's a great jazz musician; i saw him live twice Back in the Day. BUT, how 'bout some info on the engine including its intended applications? Are these built as replacements for vintage engines? I'm figuring it's 3.6 Liters, not 3600 cubic inches!
how much pressure does that super charger produce? or is that just to even the fuel mix to each cylinder? i'd think they would cast some of the large housings to save money.
but if it has fuel pumps then what's the point of having a single fan to disperse the fuel mixture? wouldn't each cylinder head have it's own intake from the carb just like a regular vehicle engine? or is that fan suppose to disperse the fuel mixture before it hits the carb?
