B-lever

General information about Wing42's Lockheed Vega.
Jarek
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B-lever

Post by Jarek » 29 Jun 2018, 20:50

Hats off to Otmar! It looks he was right from very beginning. Fortunately I was able to get answer from people familiar with vintage Lockheeds. All sources confirm that B is for Blower.
Maybe this B lever controlled some type of wet (yielding) clutch for the supercharger's impeller. This clutch type only existed on early R-1340 Wasp engine models - from A to C.
It was a subject of several improvements over time (maybe it was not so reliable) as P&W increased number of friction plates in the clutch pack. 4 plates were used on -A, 6 on -C and even 8 plates on some -D models.

Then this mechanism was eliminated and completely replaced by spring-based torsional damper invented by P&W, in principle similar to one that we have on clutch discs in modern cars. This spring-based clutch was used in models -H and above with no option to disconnect impeller.

In addition to that, with wide introduction of controllable propellers, 4-lever quadrant with B-lever was replaced by 3-lever quadrant with Prop control function.

To confirm this we would need to find some very early R-1340 model in some museum and ask for more information there.

Following this, 2 engine performance models are needed which seems like a real challenge.
Last edited by Jarek on 30 Jun 2018, 03:38, edited 1 time in total.

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Tailspin45
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Re: B-lever

Post by Tailspin45 » 29 Jun 2018, 22:05

Bravo for Otmar! Good work!
To confirm this we would need to find some very early R-1340 model in some museum and ask for more information there.
I've written to Nick Hurley, curator at the New England Air Museum and to Covington Engines and asked if they can help.

Will advise as soon as I hear back.

R-1340-A
Image

R-1340-C
Image
Last edited by Tailspin45 on 29 Jun 2018, 23:33, edited 1 time in total.
Blue skies and tailwinds - Tailspin Tommy (aka Tom)

Jarek
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Re: B-lever

Post by Jarek » 29 Jun 2018, 23:29

Wasp engine designer was Andy Willgoos. First prototype was built in 1925. His patent for such clutch concept is here:
https://patentimages.storage.googleapis ... 632526.pdf

Here is his patent of supercharger drive mechanism that he filled in 1931. But in this one, there is no external control of the clutch anymore. Pressure between plates is controlled by a nut.
https://patentimages.storage.googleapis ... 951045.pdf

Anyway I think we are closer and closer to solve this mystery. However it looks like this control mechanism was applicable to quite limited number of airplanes.

To mention other important names - construction team was managed Frederick Brant Rentschler and chief engineer was George Mead. Before moving to Pratt&Whitney, these guys worked for Wright, so this somehow could explain similar setup seen on Lindberg's Sirius with Wright Cyclone.

Jarek
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Re: B-lever

Post by Jarek » 30 Jun 2018, 03:35

There is another possibility - in 1926 Wasp was tested on Wright Apache XF3W aircraft and set multiple altitude records.
This aircraft was equipped with NACA Roots-type supercharger:
https://airandspace.si.edu/collection-o ... ude-flight
acting as 1st stage for the internal supercharger. Control valve was used there to regulate pressure. Well, the question is if Lockheed adopted the same concept on their late '20 models... This concept seems to be much more reliable than some clutch-control mechanism which could break easily.

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Tailspin45
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Re: B-lever

Post by Tailspin45 » 30 Jun 2018, 05:56

Strikes me as a rare install for specially purpose, not typical IOW. JUst a hunch
Blue skies and tailwinds - Tailspin Tommy (aka Tom)

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Tailspin45
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A preliminary investigation of supercharging an air-cooled engine in flight (1929)

Post by Tailspin45 » 06 Jul 2018, 23:10

This report presents the results of preliminary tests made on the effects of supercharging an air-cooled engine under airplane flight conditions. Service training airplanes were used in the investigation equipped with production types of Wright J engines. A N.A.C.A. Roots type supercharger was driven from the rear of the engine. In addition to measuring those quantities that would enable the determination of the climb performance, measurements were made of the cylinder-head temperatures and the carburetor pressures and temperatures. The supercharging equipment was not removed from the airplane when making flights without supercharging, but a by-pass valve, which controlled the amount of supercharging by returning to the atmosphere the surplus air delivered by the supercharger, was left full open. With the supercharger so geared that ground-level pressure could be maintained to 18,500 feet, it was found that the absolute ceiling was increased from 19,400 to 32,600 feet, that the time to climb to 16,000 feet was decreased from 32 to 16 minutes, and that this amount of supercharging apparently did not injure the engine. (author)

http://naca.central.cranfield.ac.uk/rep ... rt-283.pdf
Blue skies and tailwinds - Tailspin Tommy (aka Tom)

Jarek
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Re: B-lever

Post by Jarek » 10 Jul 2018, 00:03

Confirmed 100% - this is supercharger control lever based on data from year 1931. The question now is what was controlled...

A quote from "Flight" magazine, April 3th 1931:

"On the left side of the cockpit are situated the tail plane stabiliser control, the Exide battery box, wobble fuel pump, gas cocks, and engine controls, including throttle, spark, mixture and supercharger levers. At the base of the throttle control quadrant is located the air blast control lever".
Last edited by Jarek on 14 Jul 2018, 10:00, edited 2 times in total.

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Tailspin45
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Re: B-lever

Post by Tailspin45 » 10 Jul 2018, 00:23

Jarek wrote:
10 Jul 2018, 00:03
Confirmed 100% - this is supercharger control lever based on data from year 1931. The question now is what was controlled...
Keep in mind the test aircraft was specially configured to allow variable boost. It was a production configuration

Jarek
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Re: B-lever

Post by Jarek » 14 Jul 2018, 10:36

I did some research on "air blast" term, where it was used in the past. It appears in old instructions for extreme weather operation - like before starting engine use "hot air blast" to heat it up. So it was a Blower (German term Gebläse). This would nicely correspond to engine diagrams that we have from Tom's visit in the San Diego museum. We have 4 control levers there - Throttle/Mixture/Spark and Mixture Heater - device which redirects air heated by exhaust pipes back to the air scoop. Clearly, a lever to control amount of this air is referenced there.

If this is just basic carburetor heater (standard equipment on these engines), it would be a perfect match. But why first quoted sentence from my previous post gives reference to supercharger?

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Tailspin45
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Re: B-lever

Post by Tailspin45 » 14 Jul 2018, 15:07

I wasn't responding to your question about air blast, sorry. My comment was regarding your statement that the NACA document confirmed 100% that the B lever was for supercharger control. I just wanted to caution against basing conclusions on that document alone because the installation was designed to allow experimentation with different boost levels and thus was a special installation not typical of production models.

In any case, after reading the 1929 P&W manual for 1340-C series engines, I'm convinced that the throttle quadrant on the Vega 5C would not have a 'B' lever, because the 1340-SC1 would have had the newer internal clutch that did not have a mechanical control.

That said, your finding that air blast probably was carburetor heat makes perfect sense, especially if there is no other control for such.

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