Curtiss OX-5 Engine

eng15Ever since Arthur and his Knights of the Round Table noticed that certain swords were far superior to others, there have always been certain products which have achieved “cult” status. In the computer world, probably the best example of this is the Apple Macintosh. Even aircraft engines have their cult models, and none deserves this designation more than the Curtiss OX-5 (shown at left.)The OX-5 was first introduced in 1915, the first mass-produced aircraft engine. Even then, it was mainly restricted to training aircraft because of its relatively low 90 hp rating. With its open valving arrangement (they have to be lubricated by hand, which limits their life) it requires very diligent maintenance. The quality of its components varied wildly both because of variations at the Curtiss factory and because the engine was licensed to other manufacturers over which Curtiss had little control.

Chet and the OX-5; Langley Day 1933

In spite of these limitations, the OX-5 has earned a place in the affection of aviators that few other engines can match. Part of the reason was that it achieved its rated horsepower at 1400 rpm, which enabled the use of large, efficient propellers, making good use of its power. Chet was an OX-5 devotee from the time he first flew a plane with one 10 May 1928 at Congressional Airport; he was a member of the OX-5 Club of America. Moreover Chet promoted the engine through his air shows, and it was here that Chet ran afoul of the “higher-ups” of aviation in his day.

In the process of organising the 1933 Langley Day, he got into a dispute with the administration of the National Aeronautic Association over the inclusion of two events:

  • A “slow race” of pilots from College Park to Bowie Race Track and back, and
  • A race of airplanes powered by the OX-5 engines.

On 5 May 1933–two days before Langley Day–the N.A.A.’s board voted to sanction the entire event provided these two event were eliminated as “unnecessarily dangerous and contrary to the best interests of aviation.” Chet fired back that the NAA officials were “swivel-chair, broomstick pilots,” and went on as follows:

Members of the contest committee of the N.A.A. waited until yesterday to state their conditions on which their body would sanction our local meet. And as yet I have received no official word from them of what they feel we must do to comply with their rules…I have had no co-operation from the National Aeronautic Association and have had nothing but destructive criticism and meddling…no other course could be taken but to hold the program as planned.

I bitterly resent the treatment accorded by the National Aeronautic Association. Our program has been public knowledge for weeks and it is gross injustice for them to attempt to dictate policies at the eleventh hour.

Our program is safe and our rules have been examined and approved by officials of the aeronautics branch of the Department of Commerce, several of whom are serving as race officials tomorrow. I for one consider that the safety of the air is vested in the Department of Commerce and I am willing to abide by the decision of its officials. If the N.A.A. does not choose to sanction our air meet, the meet will go on without sanction, as it has been planned.

Chet even threatened to have N.A.A. officials who tried to stop the event removed from the field. Fortunately neither accident nor rowdy N.A.A. official marred the event.

This confrontation doubtless hardened Chet as a fan of this venerable power plant, which he put to verse as a dialogue between the OX-5 and the “Hisso” (Hispano-Suiza) engine:

PRIDE

Said the OX to the Hisso, “You’re taking my place,”
The Hisso backfired, “There’s a horsepower race.”
Said the OX to the Hisso, “That could be the rub,
But I’ll lay you a wager, there’ll never be a club
Named after you to perpetuate fame”,
And the Hispano-Suiza said, “What’s in a name?”
“Well it’s this, Mr. Hisso, let me predict
That before thirty years I’ll have you tricked,
Your pilots will scramble to get real alive
And join with the oldsters in the Club OX-5.
Maybe I was made with the size of my bore
Measuring in inches the number of four,
Eight rods and eight pistons gave a reasonable poke,
Five inches of travel was the length of my stroke.
My barrels were cast iron, my jacket Monel,
My overhead valve action oft went to hell,
My carburetor jets wouldn’t handle the dew,
And the magneto couplings were really P.U.
But I had forced lubrication in the lowor rotunda,
And thoroughly wet I weighed 375 punda.
Point sixty pounds fuel per brake horsepower hour burned
To rotate the propeller – egad, how I churned!
Revolutions per minute peaked at fourteen oh oh,
Thirty years from this date this will be rather slow
But come what may, I’m proud of my time
I truly believe I’ve kept aviation in rhyme.

So, old Mr. Hisso, you really ain’t smart
You’ll probably end up in a junk dealer’s cart,
But I’m going to live on in the memory of those
Who by the seat of their pants and the sense of their nose
Crossed the mountains and valleys, rivers and plains,
In the darndest contraptions they called aeroplanes,
They were loyal and brave, some dead, some alive,
But they’re welcome to join in that Club OX-5.

I. WILBY SHOTT

Chet was right about one thing–I’m not aware of a Hisso club anywhere!

OX-5 Specifications (in prose)

Configuration 8-cylinder, water-cooled 90 degree Vee
Output 90 hp @ 1,400 RPM
Weight, lbs 390
Displacement, in3 503
Bore x Stroke, in. 4.0 x 5.0
Compression Ratio 4.9:1
Mean Effective Pressure, psi 100
Specific Weight, lb/hp 4.33
Specific Output, hp/in3 0.18
Cruise Fuel Consumption, gal/hr at 75% power 8.0
Cruise Specific Fuel Consumption, lb/hp/hr at 75% power 0.53
Cruise Oil Consumption, gal/hr at 75% power 0.5
Cruise Specific Oil Consumption, lb/hp/hr at 75% power 0.042
Six-hour mission specific weight, lb/hp/hr (engine, fuel and oil at 75% power) 1.53 lb/hp/hr
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