SE5as and castor oil

Now that I have learnt what the 'tuning forks' were and how they worked and what dying pilots actually sang on the way down, can anyone tell me if castor oil was used in the Hispano Suiza or Viper engines in the SE5 or SE5a? Or any non-rotary engine?
In his novel 'Goshawk Squadron' Robinson has his pilots suffering the laxative problems from the castor oil in their SE5as. Was this literary license or indifferent research? Castor oil was used in the rotary engines for a specific reason, did the radials need it too or was there just alot of castor oil available?

[Darryl]

Hi Bruce,

There are far wiser minds than mine here but it is my understanding is that, as you say, Castor Oil was used in rotaries for a specific reason (I seem to recall because it didn't desolve into the fuel or break down with heat, but I could be wrong.) Inline engines used regular oils and had a normal oil tank with a circulating system. Rotaries used a "total loss" basis and for this reason didn't need to be 'run up' for as long as inlines to circulate the oil and get it to correct temperature and hence viscosity.

Derrick is an excellent fiction writer but tends to bend the facts to achieve that. He made a lot of enemies in the ex fighter pilot community with "Piece of Cake", even though IMHO it was a good read.

regards

Darryl

Only rotaries used castor oil. In-line engines used a distillate of crude petroleum. See "Aviation Engines" by Victor Page, 1919 edition, page 206 under heading Properties of Cylinder Oils. The reason for using castor oil in rotaries is also explained.

[jc]

the caster oil was only used in the wolseley-adder 200 hp/hispano-suizas. they had crankshaft problems and reduction gear failers.they thought caster oil was the fix,but it didn't help.they couldn't run them up past 1750rpms. the french, what can you say.

"It is usually found that maximum torque occurs at lower revolution speed than maximum horse-power."Quote from "Aero Engines" by G. A. Burls, London, 1916. Although some racing engines reached much greater rev's, this was always accompanied by reduction gears to the tractor screw. Normal airscrews of the day cavitated at much over 1,000 to 1.200 rpm. It was not until 1939 when variable pitch props were added to the Martin B-10 bomber that rpm could be run up without a tradeoff in power.

As the French might say 'Les huiles n'est pas les huiles.'
On the subject of airscrews of the day and reduction gears...Was the sole purpose of the gears to maintain max. torque and minimise cavitation (I had to look that up)?
I read briefly of research done at the time on different types of airscrews, designs and woods used, what did this research come up with in terms of optimum performance? If all this is too technical (and I'm not a teknishun)could someone direct me to relevant material?
Funny, I really only expected a simple yes/no answer to my original question. Thanks to all for the imput. Bruce.

[Darryl]

Bruce,

The size of a propellor is limited to that which keeps the tips below the speed of sound. The reason is that if they exceeded this, the resultant shockwave would tear the engine from its mountings. Not nice, ask Max Immelmann about the experience ( a reincarnation of him *must* be on this forum somewhere*G*).
At the same time, the area of the prop must be sufficient to fully utilise the torque of the engine or you are carrying 'dead' weight. So here is the dillema: We need a large, relatively slow revolving prop to use the 'grunt' off a massive inline but we can't make it too long. Solution, gear the beggar down.

Once again, I am quite sure the aerodynamics people can explain it better than this.

regards

Darryl
(Penny Dreadful Historian and successful completer of 'Pilot 101' )

Darryl: I don't know how we got into this, but I think we are on the verge of solving one of WW-I's great myths. But first, I found that variable pitch props were common in 1928 (Page's Modern Aircraft, 1928}Next, I called Aberdeen Proving Ground and foud out what the speed of sound is.
1120.27 feet per second, given 59 degrees ambient, 78 percent relative humidity and at sea level.
Given a prop length of 6.0479 ft and an rpm of 1200, a prop blade would describe a 19 foot circle, a blade tip going past a given point 1200 times a minute.Speed of sound translates to 1120.27 X 60, or 67,216 feet per minute.19X1200 is only 22,800 fpm. But, 67,216 divided by 19 is 3537 revs per minute to put the blade tips through the sound barrier. When the blade tips pass the sound barrier, the resulting noise should be about like small arms bullets passing close by.
Isn't it more likely that he threw a propeller tip, due to centrifugal force, and the resulting imbalance caused terrible vibration that shook loose the engine mounts? They applied copper or other sheet metal to the blade tips to re-enforce them. If he threw just the sheet metal tip it would vibrate the engine loose. What do you think?

[Brad]

Hi I didn't really see when this thread turned to the question of gear reductions. But I have some experience with airport noise and know that a cessna 206 prop regularly exceeds the speed of sound on takeoff and the solution is to reduce power to 2550 squared. (from 2800) the extra rpm is pretty much wasted making noise anyway. At the OHTM we fly a 1923 Fokker C4. which is gear reducted from 1900 rpm to 1100 rpm at full power I belive that is mostly because thats where that engine delivers the most power and no relation to the speed of sound. To the original oil question our hissos use regular oil and the rotary uses caster oil because it is vegetable based and it was hoped would not be diluted by the fuel as it mixed in the crankcase. Mineral oil has been used in rotaries without problem but the caster turned out to be a very good lubricant( there were some sticking piston valves it was blamed for though) In fact many old rotaries have been found perfectly preserved, by only the oil last run through them. VBR Brad

A kind-of-related question. I've always assumed that the brand "Castrol" derived from castor oil--that is was the first commercial substitute for castor oil. Am I correct in this?