Lift the Wankel/battery powertrain from a Mazda to use in an airplane?

Piston-powered airplanes subject pilot and passengers to unpleasant vibration. Battery-electric airplanes have minimal range.

There have been some successful applications of Wankel rotary engines in aircraft. The homebuilt folks have had some success with Mazda RX-7/RX-8 engines. Here’s an article from EAA’s Sport Aviation in 2002:

While incredibly reliable in automotive use, car engines haven’t done well running at high power settings all day every day in airplanes. The aviation-specific rotary engines thus far, such as Diamond’s AE50R, are low power engines designed for self-launching gliders and UAVs.

What if the smooth rotary engine were used to generate electricity buffered through a battery pack? Then it wouldn’t matter if the engine failed more often than 1930s-style Continental and Lycoming piston engines. An engine failure would mean using a 20-minute battery reserve to land. Is there a mass-market low-cost battery+Wankel combination available? Yes! From “The Hybrid Wankel Rotary-Powered Mazda MX-30 R-EV Is Finally Here. Here’s How It Works” (Autopian, January 2023):

For starters, the engine doesn’t drive the wheels. It only serves as a generator connected to a motor/generator unit to send power to the battery pack. The battery pack then provides juice to an electric motor which powers the wheels. This means that despite burning gasoline, the MX-30 R-EV should theoretically have the seamless power delivery of an EV, and it should be able to keep the Wankel engine at its “sweet spot” for efficiency for a significant portion of its on-time.

As for deeper details on that rotary engine, there’s the presence of direct injection, something never attempted before on a production rotary engine. The side housings are aluminum and coated with plasma for low weight and friction management respectively, all while being just 80 mm wide. For the sake of longevity, the apex seals are 25 percent wider than the ones on an RX-8’s RENESIS engine, clocking in at 2.5 mm. The result is 73.7 horsepower from just 830 cc of displacement. Curiously, although rotary engines love to rev, Mazda claims that peak power hits at just 4,700 RPM. That might sound weird for a high-revving Wankel, but it should translate to very low noise.

At 214 pounds, it looks like this engine is fairly heavy for its horsepower (a little heavier than an 80 hp aluminum piston engine), but given the high efficiency of electric drive maybe this would still work out well for a 2-seater.

Readers: Where’s the flaw in this path toward aircraft powered by a mass-market powertrain?


Full post, including comments

How did Hurricane Fiona, a Category 1 storm, knock out Puerto Rico’s power?

A few media-following friends in the Northeast have been checking in, concerned that Hurricane Fiona, which knocked out power in Puerto Rico, is also trashing our neighborhood. They are reassured to learn that Puerto Rico is 1,000 miles from Palm Beach County, but it has made me wonder… given that (1) Fiona is only a Category 1 storm, (2) Puerto Rico can expect something similar every year or two (history), and (3) the power grid in Puerto Rico was recently rebuilt to the latest standards (after the 2017 Category 5 Hurricane Irma), why were the reported 85 mph winds enough to take the system out?

Is it simply impossible to make above-ground lines robust enough to handle 85 mph winds? Is the problem that trees will inevitably come down and break the lines even if the lines wouldn’t have been blown down? (But a newly engineered grid should be able to handle quite a few individual tree impacts because the power would be routed around the cut line.)

From state-sponsored NPR in 2021:

It’s been four years since Hurricane Maria devastated Puerto Rico’s electric power grid. Yet even after billions of dollars were allocated by the federal government to repair it, the island’s energy infrastructure is still in terrible shape. Blackouts continued this summer as the two entities responsible for operating the grid pointed fingers at each other over who is to blame. One of those two entities is Luma, a private company that was awarded a contract last year to distribute electricity around the island. The other is the Puerto Rico Electric Power Authority, known as PREPA, which used to be in charge of the whole system and now continues to operate the power plants.

The restoration process is very bureaucratic because you have Luma going through FEMA’s process, going through the Puerto Rico Energy Bureau’s process. And you also have Luma going through federal process and going through Puerto Rican process. And you know what? There’s not a single work already done with reconstruction funds. They’re still planning and designing. So this will take a lot of years before we see something better.

An IEEE article from 2018 doesn’t explain any of the engineering or technical details:

This past December, I traveled to Puerto Rico to report on this massive undertaking. I found contradictions everywhere I went. I saw utility workers fanned out across the island, yet progress remained excruciatingly slow. I met rank-and-file PREPA employees working flat out to restore power, yet each day brought a new report of fumbles at the utility’s top levels. And I heard many smart and exciting ideas for how to build a modern, resilient grid in Puerto Rico, even as the urgent need to restore power meant resurrecting the vulnerable existing system.

KSUA to TJSJ (skyvector):

Are we going to see “I stand with Puerto Rico” Facebook profile images? Or will people stick with this one:

Full post, including comments

Audible’s tale of an engineering hero: The Man Who Knew the Way to the Moon

It is rare for engineering to be the subject of literature and entertainment and even rarer for an engineer to be the subject. Audible’s The Man Who Knew the Way to the Moon is a welcome outlier. Although I was once a proud Fortran programmer at NASA’s Goddard Space Flight Center (the Pioneer Venus project), I hadn’t realized that the original idea for the moon landing was to fly a huge vehicle and enough fuel for the return trip straight to the lunar surface. Audible’s work is about John Houbolt, who fought the conventional thinking and endured all of the bureaucratic infighting to promote the idea of a small vehicle that would land on the moon, thus requiring only a tiny fraction of the fuel to get back to Earth. After escaping the moon’s gravity, the small vehicle would rendezvous with a bigger spacecraft in lunar orbit (“lunar orbit rendezvous” or “LOR”) and then the astronauts could all go home.

Trigger warning: the book implies that members of the 2SLGBTQQIA+ community, engineers of color, and engineers who identify as “women” played no role in getting astronauts to the moon.


Full post, including comments

Is 5G a total fraud?

Mobile phone service back in Maskachusetts was generally terrible, whether the iPhone 12 Pro Max indicated “LTE” or “5G” up at the top right. I attributed this to hills generating multipath and the righteous demanding that cell towers be built in someone else’s town.

We’re living in Florida, though, where a municipal landfill is the only hill, and the government encourages any kind of useful infrastructure. I think that all of the preconditions for awesome mobile data service have been fulfilled:

  • I’m fully vaccinated and so is our golden retriever, Mindy the Crippler
  • The Verizon bill is on autopay
  • the iPhone usually shows 3 or 4 bars of 5G
  • there are no tall buildings or hills around

Yet the service simply doesn’t work. It can take minutes to send a single photo via iMessage, for example. Looking up stuff on Google can be impossible. Navigating via Google Maps results in an “offline” display, even when the phone shows 3 bars of 5G.

Could it be that there is a working LTE service in most locations, but the phone sees 5G and latches onto it even when the 5G radios are simply broken? I’ve experimented with telling the phone to use LTE only, but that didn’t seem to help. Sometimes the Verizon network yields impressive numbers on a Speedtest, comparable to high quality home broadband circa 2010, but for any given request it is unpredictable whether it will take a fraction of a second or minutes.

Is this issue unique to my iPhone 12 and it will be #ProblemSolved when I upgrade to the glorious world of iPhone 13? Or are other folks having similar issues (3 or 4 bars of coverage yet it is tough to download an ordinary web page)?

Waiting for a page to load on 5G:


Full post, including comments

Should the Nord Stream pipeline be considered an engineering wonder?

The seafloor pipeline from Russia to Germany has been in the news lately (see “U.S. urges Ukraine to stay quiet on Russian pipeline” (Politico): “The Biden administration is asking an unhappy Ukraine not to make waves, as it nears Russia-Germany pipeline agreement.”; I guess Joe Biden finally found a pipeline that he could love! (compare to “Keystone pipeline canceled after Biden had permit blocked” (USA Today)).

I wouldn’t have thought that a 760-mile seafloor pipeline could be done as a practical engineering matter. From Gazprom:

The outside surface of pipes has a special anti-corrosion concrete coating. The concrete coating is made of high-density iron ore, which is crushed, mixed with cement, and put on pipes. As a result, pipes are wrapped in spiral reinforcement, which is filled with concrete, and then treated with steam in special tunnels for 24 hours. The concrete coating helps meet several challenges at once. Firstly, it keeps the pipeline on the seabed, preventing it from drifting off with undercurrents. Secondly, it serves as insulation, protecting the trunkline from outside mechanical damage.

The genius of Russian engineering? Wikipedia says that it was actually the Italians who figured out how to do this:

On 19 March 2007, Nord Stream AG hired Italian company Snamprogetti, a subsidiary of Saipem, for detailed design engineering of the pipeline. A letter of intent for construction works was signed with Saipem on 17 September 2007 and the contract was concluded on 24 June 2008

Readers: Should we be awed that this is working at all? Is the best analogy the Portuguese and other early European trips around the Horn of Africa to India and China? It is tough to believe that the sea voyage was actually more efficient than the overland one, but a lot of middlemen were cut out.

(My Ukrainian friends are not fans of this Biden Administration decision, but it won’t cost Uncle Joe any votes because these non-virtuous immigrants to the U.S. already disliked Biden/Harris for their Bigger Government policies.)


  • “The Security Implications of Nord Stream 2 for Ukraine, Poland, and Germany” (Wilson Center): … repairing the current Ukrainian-Polish pipeline would cost around €6 billion. The construction of Nord Stream 2, however, would cost €10 billion. Experts believe that Nord Stream 2 is diverting gas from the preexisting Ukrainian-Polish pipeline, meaning Europeans will receive the same amount of gas, if from a different source. … completion of the pipeline would see the European continent increase its dependence on Russian gas. If tensions were to rise between Europe and Russia, Russia could turn off the pipeline, leaving millions of Europeans without gas. Second, Europe’s reliance on Russian gas would present Russia with the leverage to further meddle in the affairs of its neighbors without consequence. Third, the new pipeline would divert the flow of gas from Ukraine and Poland, leaving these two countries to face a substantial revenue loss. They would also be forced to pay higher gas prices.
Full post, including comments

Why don’t smartphones have PLB capability?

A friend was recently involved in a helicopter rescue effort described in “‘Not knowing is so hard.’ Hiker rescued after 5 days without food in California forest”:

A hiker was rescued from a canyon in a California forest after going missing for five days without food and little water, officials said.

George “Dave” Null, 58, went missing in the Angeles National Forest May 15, according to a news release from the Los Angeles County Sheriff’s Department. It took a massive search effort, involving at least five agencies, to find him, the sheriff’s department said.

Null was spotted at creek base Wednesday evening while a helicopter crew searched Bear Creek in the canyon east of Triple Rock, according to the Montrose Search and Rescue Team.

This made me wonder why smartphones don’t have a personal locator beacon capability. Coronapanic has proven that there is no limit to our risk-aversion. Why wouldn’t we engineer slightly thicker phones with a fold-out antenna and a guaranteed dedicated power reserve that can be used as a PLB when we’ve gotten lost, e.g., on the way to or from the vaccine booster clinic or the P100 mask store?

The obvious disadvantage of this approach is that the phone becomes slightly bulkier and heavier. But if we’re willing to wear masks all the time and take non-FDA-approved vaccines why aren’t we willing to carry a slightly heavier phone if it could save just one life?


Full post, including comments

Soundproofing for an air conditioner/heat pump (success story)

We had a Princess and the Pea situation in our house in which a moderately quiet A/C condenser next to a bedroom was deemed too loud, especially when clicking on. This is a high-end Carrier-built unit, so it is somewhat louder than a Japanese split-system, but quieter than almost anything else U.S.-built.

We were able to eliminate the annoyance with a blanket from Acoustical Solutions that we hung on the wall adjacent to the condensers (quilted part facing the A/C unit; smooth part against the wall). We also wrapped one that was roughly the same height as the condenser around the side so as to block transmission to a window. It would be a lot more attractive it we built a wooden hutch around it, but it is highly functional just hung on a metal fence U-post (less than $10 from any hardware store).

We bought the ABBC-13 two-inch thick “AudioSeal” blankets, one 96″x54″ (custom made to have the grommets on the long side) and one 54″x54″. Total cost, including shipping and Maskachusetts sales tax, was $890. We’ve had them outdoors through one New England winter and they still look good.

Leaving this here in case anyone is searching for a similar solution.

Full post, including comments

The Ever Given’s interaction with the Suez Canal

“The bank effect and the big boat blocking the Suez” (FT, mostly paywalled, but the link might work because I’ve included a Facebook ID) is interesting and reveals some similarities to Queen Elizabeth 2‘s grounding off Cape Cod, in which the ship dug a 9′ hole in the water by traveling at 25 knots. Some excerpts:

The canal has been getting wider and deeper over time…

But it is not so wide/deep that displaced water can be ignored.

Is it time to read Parting the Desert: The Creation of the Suez Canal? (Remember that the Pharaohs who purportedly oppressed the Jews built this first!)


Full post, including comments

The Brave New World of Human-carrying Drones will have the same dashboard as the old world

“Joby Picks Garmin G3000 For eVTOL” (Avweb) suggests that the exciting new world of drones, which I hope will have enough software intelligence to prevent flying into obstacles (see New York helicopter crash: why not robot intelligence? and Aviation weather reports at the time of Kobe Bryant crash), will have the same dashboard as today’s business jets: a Garmin G3000 (seemingly way more complex than it needs to be).

I’m wondering if this will extend the life of traditional flight schools using traditional trainer airplanes and helicopters. If a lot of our skills translate into the Super Drone world (I’m hopeful that “eVTOL” is not the final term for this category of aircraft), perhaps folks with standard pilot certificates will still have a role to play.

Here’s what the G3000 looks like inside a Cirrus Vision Jet (three touch screens on the bottom that control the two non-touch screens on top):

Full post, including comments

Why not heated furniture to fight coronaplague?

In their righteous muscular efforts to “control” coronavirus, some state governors and city mayors have ordered restaurants shut down, except for outdoor dining. In response, restaurants have built four-sided tents filled with CO2-emitting propane heaters. It is unclear why this is different from being indoors, other than the lack of a real HVAC system. The tent sides are necessary, though, because otherwise the propane heat will blow away.

Why not heat the customers instead of the air?

Back in 2010, I wrote Heated Furniture to Save Energy?

A lot of cars have heated seats. When the seat heater is on, most drivers will set the interior temperature 3-7 degrees lower than with the seat heater off. Why not apply the same technology to houses?

Imagine being at home in a 65-degree house. Even in a T-shirt and jeans, it would probably be comfortable to walk around, stir a pot on the stove, carry laundry, scrub and clean, walk on a treadmill while typing on a computer (as I’m doing now!). However, if one were to sit down and read a book, it would begin to seem cold. Why not install heat in all of the seats and beds of the house? And sensors to turn the heat on and off automatically? In a lot of ways, this would be more comfortable than a current house because the air temperature would be set for actively moving around while the seat temperature would be set for sedentary activities.

There is a fine line between brilliant and stupid, of course, but could it be that coronaplague has pushed this idea over the line?

A Dutch company, sit & heat, seems to have thought of this: heated cushions that can fit into a standard frame. Serta makes a chair-shaped electric quilt (could not survive outdoors) for only $64. A plastic chair with a built-in 750-watt heater is $900 (Galanter & Jones; they have sofas too at roughly $6,000 and claim they are “cast stone”).

If heated chairs were mass-produced in Asia, presumably the cost per chair would be only about $100 more than a regular outdoor chair. That should be affordable for a restaurant.


Full post, including comments