Remanufacturing A Rotary Airplane Engine

If someone tells you they have seen a rotary engine, the chances are that you will immediately think of a Wankel engine, as you might find in some of the more exotic Mazda sports cars. But there is another rotary engine that has a prior claim to the name, and it can be found as the power unit for many early-twentieth-century aircraft. In these rotary engines the cylinders are arranged radially around a stationary crankshaft, and it is the engine itself that rotates. They have the advantage of extreme simplicity, smooth power, and a low parts count, at the expense of total loss lubrication, a relatively large rotating mass, and some difficulty in controlling their power. These rotary engines were largely obsolete by the 1920s, but  recent upsurge of interest in WW1-era aircraft has led to the creation of a small demand for them. New Zealand based Classic Aero Machining Service have stepped in to fill that gap and are remanufacturing the Gnome radial engine, the most numerous design of that era.

For anyone with an interest in internal combustion engines, the Gnome is a fascinating study. It’s a nine-cylinder design that runs a four-stroke Otto cycle, but instead of the two or more valves you might be familiar with from your motor vehicle it has only a single valve. The so-called Monosoupape design uses its valve for both fuel and exhaust, opening it on the inlet stroke as well as the exhaust stroke. The simplicity of a single valve and no carburetor is thus offset by a difficulty in varying its power , so rotary engines would frequently reduce the number of firing cylinders in lieu of throttling back.

The CAMS Gnome is a faithful copy of the original, but with modern metallurgy and the addition of an electronic ignition system. The original castor oil is still used — it seems classic aviation buffs like the smell — but becuase it is notorious for leaving sticky deposits in the engine they are evaluating modern alternatives. They have some technical details on their website, and there’s a good chance you my hear one of their engines one day at an air show near you.

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Three Engines for Every Lada

If you don’t live in a former Eastern Bloc country, odds are that you’ve never seen a Lada driving around your neighborhood. This car is ubiquitous in Russia and its neighboring countries, though, and for good reason: price. Lada gave many people access to affordable transportation who otherwise would have been walking, but this low price means that it’s a great platform for some excellent car hacks as well.

The guys at [Garage 54], an auto shop in Russia, outfitted one of these discount classics with two extra engines. This goes beyond normal bolt-on modifications you typically see to get modest horsepower gains from a daily driver. The crew had to weld a frame extending out of the front of the car to hold all the extra weight, plus fabricate all the parts needed to get the crankshafts on each engine to connect to each other. After that, it was the “simple” job of tuning the engines to all behave with one another.

This video is really worth watching, as the car was also upgraded with a dually setup on the back with studded tires for extra grip on their ice track. Odds are pretty good that this car isn’t street legal so this is likely the only place they’ll be able to drive it. Other things can be built out of Ladas as well, like lawn mowers for example.

Thanks to [g_alan_e] for the tip!

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This Monowheel Is Bright Orange, And We Want One

Monowheels are a singular form of transport. Like electric scooters and the Segway, they are remarkably impractical for getting from point A to point B, are expensive to build or buy, and make you look faintly silly as you ride them down the street. However, we’d be hard pressed to find a member of the Hackaday team that wouldn’t at least want a go on one for half an hour. [MakeItExtreme] felt the same way, and built one of their own.

The build starts with a tube bender, used to form 40mm tubing into a continuous circle to form the main wheel. Teflon is then turned to produce several rollers that interface the main wheel to the inner frame. Several small motorbike tyres were cut apart to create the tread to provide some decent grip. Power comes courtesy of a 110cc four stroke engine, allowing this thing to go just fast enough to get the rider seriously injured in the event of an accident. The team reports stability is poor at low speed, but remarkably good once above 30 km/h.

The team did a great job, and we particularly enjoy the bright orange paint scheme and fetching decals that really finish it off well. The monowheel concept is remarkably similar to the diwheel, which we’ve seen applied to old Fords with somewhat terrifying results. Video after the break.

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Building The World’s Smallest Jet Turbine By Hand

There are very few machines as complex to build as a turbojet engine. The turbine blades on a commercial airliner are grown from a single crystal of metal. The engineering tolerances are crazy, and everything spins really, really fast. All of these problems aren’t a concern for [Igor], who’s building what will probably end up being the world’s smallest turbojet engine. He’s doing it in his home shop, and a lot of the work is being done by hand. We don’t know the Russian translation for ‘hold my beer’, but [Igor] certainly does.

The design of this turbojet — as far as we can tell — is a centrifugal flow turbine, or something that’s not terribly different than the projects we’ve seen that turn the turbocharger from a diesel engine into a jet. The innovation here is using a lathe to machine the compressor stages by mounting an end mill to the headstock and the compressor blank on the cross slide, in a rotary table. It’s weird, but you really can’t argue with something that looks like it’ll work.

[Igor] has made a name for himself by creating some crazy contraptions. The most impressive, by far, is a gigantic remote controlled plane, powered by a handmade jet engine. This is an enormous fiberglass plane with a homebrew engine that spins at 90,000 RPM and doesn’t fly apart. That’s impressive by any measure.

[Igor] is posting a lot of his build process on YouTube and Instagram, including heat treating the compressor stages with a blowtorch. This is an amazing project, and even if this tiny turbine will be able to self-sustain, that’s an amazing accomplishment. You can check out a few more videos from [Igor] below.

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JB Weld – Strong Enough To Repair a Connecting Rod?

JB Weld is a particularly popular brand of epoxy, and features in many legends. “My cousin’s neighbour’s dog trainer’s grandpa once repaired a Sherman tank barrel in France with that stuff!” they’ll say. Thankfully, with the advent of new media, there’s a wealth of content out there of people putting these wild and interesting claims to the test. As the venerable Grace Hopper once said, “One accurate measurement is worth a thousand expert opinions“, so it’s great to see these experiments happening.

[Project Farm] is one of them, this time attempting to repair a connecting rod in a small engine with the sticky stuff. The connecting rod under test is from a typical Briggs and Stratton engine, and is very much the worse for wear, having broken into approximately 5 pieces. First, the pieces are cleaned with a solvent and allowed to properly dry, before they’re reassembled piece by piece with lashings of two-part epoxy. Proper technique is used, with the epoxy being given plenty of time to cure.

The result? Sadly, poor — the rod disintegrates in mere seconds, completely unable to hold together despite the JB Weld’s best efforts. It’s a fantastic material, yes – but it can’t do everything. Perhaps it could be used to cast a cylinder head instead?

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Results of 3D-Printed Cylinder Head Testing Fail to Surprise

It’s the suburbanista’s weekend nightmare: you’re almost done with the weekly chores, taking the last few passes with the lawn mower, when you hear a pop and bang. The cylinder head on your mower just blew, and you’re out of commission. Or are you? You’ve got a 3D printer – couldn’t it save the day?

If this bench test of plastic cylinder heads is any indication, it’s possible – just as long as you’ve only got 40 seconds of mowing left to do. [Project Farm] has been running all sorts of tests on different materials as field-expedient cylinder heads for small gasoline engines, using everything from JB Weld epoxy to a slab of walnut. For this test, two chunky heads were printed, one from ABS, of the thermochromic variety apparently, the other in PLA. The test went pretty much as expected for something made of thermoplastic exposed to burning gasoline at high pressure, although ABS was the clear winner with two 40-second runs. The PLA only lasted half as long before the spark plug threads melted and the plug blew out. A gasket printed from flexible filament was also tested, with predictably awful results.

As bad as all this was, it still shows that 3D-printed parts are surprisingly tough. Each part was able to perform decently under a compression test, showing that they can stand up to pressure as long as there’s no heat. If nothing else, it was a learning experience. And as an aside, the cylinder heads were printed by [Terry] from the RedNeckCanadians YouTube channel. That video is worth a watch, if just for a few tips on making a 3D-printed copy of an object. Continue reading “Results of 3D-Printed Cylinder Head Testing Fail to Surprise”

Out Of Batteries For Your Torch? Just Use A Mini Nitro Engine

We can certainly relate to an incomplete project sowing the seed for a better one, and that’s just what happened in [JohnnyQ90]’s latest video. He initially set out to create an air compressor powered by a nitro engine, and partially succeeded – air was compressed, but not nearly enough to be useful.

Instead, he changed tack and decided to use the 1 cc engine to make a small electric generator. [JohnnyQ90] is, of course, no stranger to the nitro engine, having previously brought us the micro chainsaw conversion, and nitro powered rotary tool. This time round, the build is a conceptually simple task: connect an engine to a DC motor and you’re done. But physically implementing it in an elegant way is a different story, and this is always where [JohnnyQ90] shines; we never get tired of watching him produce precision parts on the lathe. A fuel tank is made from a modified Zippo can and, courtesy of a CNC milled fan and 3D printed shroud, the motor air cools itself.

Towards the end of the video, [JohnnyQ90] plays with the throttle a little, causing the bulb connected to the generator to brighten accordingly. It might be fun to control the throttle with a servo and try to regulate the voltage on the output under different load conditions.

We love novel ways of creating electricity; previously we’ve written about how to generate power from a coke can, as well as this 120 W thermoelectric generator (TEG) setup.

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