THE HISPANO-SUIZA V-8 718 & 1127c.i. CRANKSHAFT PROBLEMS

[m9a3r5i7o2n]

Starting the Hisso is usually a fairly straightforward procedure, although if the engine is hot and the magnetos are weak you can wear out your prop-swinger in no time as the big V-8 obstinately refuses to fire up. Normally, you give the engine a couple of shots of prime, call, "Switch off!" to your helper, and wait while the propeller is turned through three or four revolutions. Then the booster mag comes into play. This is a small, hand-cranked magneto at the lower right corner of the instrument panel that sends extra current to the spark plugs for starting. If the engine is juiced up just right, and the propeller is in just the right position, you can put the mag switch to Both, crank the little handle on the booster mag, and the engine will start instantaneously. Usually this doesn't work, and you have to call the prop-swinger back to his task. You call, "Contact!", wait until after you see him start to swing, never before, and then start to crank the booster. Hopefully the Hisso catches and settles into a low, rumbling idle. It will idle below the last mark on the tachometer, but it's better to bump it up to 650 rpm or so to keep some cooling air moving through the radiator. This is especially true when the engine is warm, like in between rides.
M.L. Anderson

From; PilotWeb

[m9a3r5i7o2n]

Yesterday I was going thru some old threads and one of them was about TORQUE, HORSEPOWER AND R.P.M. this struck me as an odd thing to question but then as I thot more about it occurred to me that the Torque the old engines needed to get any Horsepower at all at the R.P.M. that they ran at, must have required a lot of torque and therefore the engines must have been more heavily loaded than I thot before. The following is the result of that thinking. Notice the heavy torque needed to get 220 horsepower out of a Hispano-Suiza at 2100 r.p.m.

HORSEPOWER = Lbs. FT. TORQUE x R.P.M. DIVIDED BY 5252
220 HP = 550.2 Ft. Lbs x 2100 DIVIDED BY 5252 = 220 HP. O.K.

Lbs. FT. TORQUE = ( HORSEPOWER DIVIDED BY R.P.M.) x 5252
(220/2100) x 5252 = 550.2 FT. LBS TORQUE O.K.

R.P. M. = 5252/LBS. FT. TORQUE x HORSEPOWER
R.P.M. = 5252/550.2 x 220 = 2100 r.p.m. O.K.

5252 IS A CONSTANT!!!!

One of the things that may easily confuse many people is the use of a torque figure/number to describe the maximum Torque output at a much lower figure than the maximum horsepower output. I believe that this was used originally to show the power band in automobiles and to show the engines tractability in daily usage. This would be true especially before the use of Hydraulic torque converters plus three and four speed mechanical gearing. This has little or no use in an aviation engine because an aviation engine is rarely used at its maximum torque figure unless it happens to be the r.p.m. that the engine puts out its maximum useable h.p. Just ask yourself how many times have you seen maximum torque called out on an aircraft engine. I cannot recall a single case!

Yours, M.L. Anderson

[shackleton]

[ After 1932 the amount of 180 degree crankshaft engines built is very small. I believe the 1939 Mercedes V-8 for the Tripoli race were 90 degree crankshaft.

Yours, M.L. Anderson[/quote]

The Mercedes W165 that won the Tripoli Grand Prix had a V8 engine

90 degree V8
1495 cc
over square bore 64mm stroke 48mm
4 Over head camshafts
power output 263 - 278 bhp @ 8250 rpm

[Dan_San_Abbott]

M. L. Anderson:
I was curious on how the Constant Factor of 5252 was determined? I have found this thread the most interesting I have read on the Forum.
In a discussion with Lee Branch, several years ago he informed me that the reduction gear story was a cover-up for the real problem, which was, the failure of copper oil feed pipe to the reduction gears. He said that Hispano-Suiza had covered up their real problem, which was a design error!
Blue skies,
Dan-San

[jumpinjan]

Dan,
Watt stated that 33,000 foot pounds per minute of work was equivalent to the power of one horse, or, one horsepower.
Visualize an engine crankshaft turning a one pound weight on a 1 foot radius. Rotate that weight for one full revolution against a one pound resistance. The engine moved it a total of 6.2832 feet (Pi * a two foot circle), and, incidently, we have done 6.2832 foot pounds of work in one cycle.
Watt said that 33,000 foot pounds of work per minute is one HP. If we divide the 6.2832 foot pounds of work we've done per revolution of that weight into 33,000 foot pounds, we come up with the fact that one foot pound of torque at 5252.1 rpm is equal to 33,000 foot pounds per minute of work, and is the equivalent of one horsepower.
Horsepower = (Torque ft/lbs) * RPM/5252
Jan

[m9a3r5i7o2n]

To Jan;

I'm happy that you explained it as I left it out of my post. I wrote from the place where I found it on the Internet when I became interested in a post that one person didn't know about the relationship of torque, horsepower and R.P.M.

I was somewhat surprised at the amount of torque it required to make the horsepower of 220 at 2100 r.p.m..
It certainly added to my belief that the Hispano-Suiza 718 c.i. engine was right at the edge of its design strength with the mistake of the unbalanced crankshaft, failure to put a Oil Pressure Relief Valve on the Lubricating system and several other items that aren’t as important as they were.

Were you as surprised as I? I would be pleased if you were to check my figures as it really staggered me when first I saw it.

Yours, M.L Anderson

[Butch]

Ellic Somer used to have several geared Hisso engines. He had the gears analyzed and the verdict was that they had mismatched pitches. I can find out more later but Ellic was sure that they were made by two different factories and simply ate each other up.
Pete

[m9a3r5i7o2n]

Pete; This would not surprise me one bit with all the other things that were going on to get these engines in the field and we must always remember that a huge amount of war profits were involved. The adage follow the money applied then just as now.

The old method of making sets of gears/pinions in the first part of the century was the making of gears in the same shop as the pinions, sometimes with the machines standing side by side and testing them on machines and placing them in boxes or wired together as matching pairs.

Also the sets should be marked as to the maker, with the manufacturers name or a mark of some sort stamped on the part before any machining was done and then the heat treating and or stress relieving in the manner required for that particular type of gear/pinion was done.

Also the stamping of gears/pinions/idler wheels is a dangerous method of marking as the old stamps were not rounded as later stamps were to prevent stress risers at the stamping area. Parts should have been Serialized!

Also lets talk about the use of a helical gear/pinion instead of a straight tooth wheel set. In my opinion this was a big mistake of Birkigt. He failed to put an Oil Pressure Relief Valve in the engine and then he put in Helical Gear/Pinion set. Not very good thinking I don’t think. Putting Helical gear/pinion into an engine with an exhaust about two three feet from the Pilots ears was not very good thinking in my view. Not even in 1915/1918.

Helical gears are usually used to lower noise of the straight tooth gear/pinion and sometimes to promote smoothness of engagement which is not a real requirement of a
propeller setup.

Of course maybe he was very tired as the making of this engine and then taking on the chore of the 1127 c.i. was really too much I believe. But then he was the only man that had the foresight to do the 718 c.i. engine and quite likely the only man to see it thru even if he hadn’t of taken on the task of the 1127 c.i. engine.
Yours, M.L. Anderson

[m9a3r5i7o2n]

shackleton; If you are really interested in this engine you really should get the book entitled:”Quicksilver”, by Cameron C. Earl ISBN 0 11 290550 1.

It even has pictures of the Tripoli engine on page #131, even has a drawing of the 90 degree crankshaft. Magnificent book on one of my favorite engines.
Yours, M.L. Anderson

[m9a3r5i7o2n]

To illustrate the torque delivered to the propeller with the reducer box engine 2,000/1,333 (1 to .6665 ratio) and the engine used was the Hispano-Suiza 8BcD 238 horsepower at 2,240 r.p.m. Propeller r.p.m. = 1492 r.p.m. torque at engine is 558 lbs ft. torque and at the propeller is 837.3 lbs ft. torque.

The 8Beb engine, probably the best engine Hispano-Suiza produced, was 238h.p at 2,240 r.p.m. same as above but the reducer box was 2,000/1,500 (1 to .75 ratio) same engine torque at 558 lbs. ft. but torque at propeller 744 lbs ft.

The engine above had 3 important changes such as the bigger oil pump with Pressure Relief Valve and a Flexible magneto coupling.

M.L. Anderson