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Hagerty Employee

Smithology: 15 simple rules for dating my 1930s French propeller car

The following owner's-manual text was uncovered in a barn in Europe in the year 2000, next to the ruins of the only surviving French Helicron automobile. That text has been translated and excerpted below from the original French.
Advanced Driver

Zut alors!
Intermediate Driver

Reading the initial prose, I'm thinking I don't know where the period owner's manual ends and the Smith begins. Are you sure it never actually existed?
Intermediate Driver

La vie est courte et tu vas mourir.
Duc le Marquis de Gheeyootine
Advanced Driver

Sam puts his life on the line, a potential sacrifice to his art. I urge other readers to enjoy his presence among us whilst we can.

40 hp and you couldn't get up that hill?

Man, that thing would clear the crosswalks...
New Driver

There is a similar "car" on display at the Museum of Arts and Industries in Paris, France. I'll see if I can find my photos of it.
Intermediate Driver

According to the dash plate, the car originally came with a 3 horse power (unless HP meant hippo power back then) engine. I imagine with the current 40 horse power engine the safety margins are reduced 15 fold. Before the disclaimer, I was thinking that these French really have a sense of humor. After viewing the car, I still do.
Intermediate Driver

I doubt that it was 3 horsepower. 3 hp is just the model number. 40 hp is scarcely adaquate. 3 would go nowhere.

The 3 horsepower is probably accurate, but TAXABLE horsepower. I don't know the origin of the chart I came across, but it gives a 2000-2006 4.0L Wrangler six (190 hp) a taxable rating of 36 HP -- about 20% of the real rating. The 190 HP is GROSS, not the old pre 1972 NET rating, which would be ~240-245 HP, 15% if using 240. So that makes the original engine ~20 HP. For comparison a 1932 Ford Model B four (3.29L, 201 CID) put out 50 HP.

From Wikipedia:
The Cheval Fiscal, often abbreviated to CV from "chevaux-vapeur" (literally 'steam horses') in tax law, is used for the issuing of French registration certificates known as "grey cards" (cartes grises). It is an administrative unit originally calculated partly from the power of the engine and used to calculate the amount of tax that may be due at the time of registration.

The Citroën 2CV (two tax horsepower) was the car that kept such a name for the longest time.

Its use in France dates from 1 January 1913. It was updated in 1956, with further revisions in 1978 and a new emission-based system introduced in 1998.

It was originally defined using the following formula:

C V = n × D 2 × L × ω × K {\displaystyle CV=n\times D^{2}\times L\times \omega \times K} {\displaystyle CV=n\times D^{2}\times L\times \omega \times K}


n {\displaystyle n} n is the number of cylinders,
D {\displaystyle D} D is the cylinder bore in centimeters,
L {\displaystyle L} L is the stroke in centimeters,
ω {\displaystyle \omega } \omega is the engine speed in revolutions per second,
K {\displaystyle K} K is a coefficient depending on the number of cylinders (single-cylinder engine : 0.00020; two-cylinder engine : 0.00017; four-cylinder engine: 0.00015; six-or-more-cylinder engine: 0.00013)
Advanced Driver

Thanks for beating me to it!

“3 h.p.” probably is a transposition from “3CV” (3 “chevaux vapeur”, or “steam horsepower”): the mighty Citroën 2CV, named after its “2 Chevaux Vapeur” had 9 mechanical h.p., not 2 — so “3 chevaux vapeur” would be more than 9 h.p., but it is not an arithmetic progression.

You can scroll down to the French formula used before 1956 here:

Such a crazy car. Talk about alternative transportation.

I loved it! Sam gets himself into a 40hp monster and drives it. Many Blessings to the restorers and Lane Museum. Yes, I'll try to go this Summer and see this marvel.
Intermediate Driver

Must be a trip to drive, Hills Bad!, maybe you could put wings on it to fly over hills?

Call me a skeptic, but has the French to English translation been embellished a bit by the author?
Another very entertaining article by Monsieur Smith.

It's French. That explains a lot.
New Driver

We loved our visit to the Lane Museum in 2020 (just before the lockdown) and the Helicron was not by any means the only quirky car in the collection! As for this delightful article.... I'm channelling Bruce McCall, the maniac behind "Zany Afternoons."

Anybody who mentions Bruce McCall (in a good way) automatically gets my "like"! Fantastically funny man!

Around the same time a German inventor demonstrated a monorail train that was suspended from a track instead of riding on it. This thing was driven by a huge propeller at the rear. It was no more successful than this car.

With rear steering, no question the designers were aircraft devotees. "Hellicron" indeed!

While evidence tends to suggest that more than one of these were built, I really can't see how this can get to, let alone past, the prototype stage without revealing some fairly glaring flaws

And this obviously was conceived before the day of the plastic handle bag

I would not have been able to get through this manual without tossing in the Isadora Duncan quote. "Well, so long -- I'm bound for glory!" That business with the scarf must have happened all the time.
Advanced Driver

It is notable that Mrs.Eugenia P. O'Halloran of Keokuk, Iowa, was a good friend of the wife of the esteemed Mayor Shinn of River City, Iowa, Eulalie Mackecknie Shinn. And contrary to this screed, Eulalie Mackecknie Shinn, the wife of Mayor Shinn, stated that during the 76 Trombone incident in River City, it was Mrs. Eugenia P. O'Halloran's famous pies that fueled the festivities, including when the dancers, led by Mr. Washburn, did the Shapoopie, at Tommy's request.
Intermediate Driver

For a taste of the experience (for those living or travelling on the West Coast, I suggest you take a look at Mr. Nieman has his Pratt and Whitney aircraft engine on view in lovely St. Helena, California.

Spectacular!!! Vive la France!

That design seems the best candidate for a flying car!

That was a really interesting way to go about making a car that you didn't have to shift manually.