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R-1340 "Wasp C" With Supercharger Control?

Sat May 19, 2018 3:37 pm

I was wondering if anyone here has any experience with R-1340-C engine installations (or other early Wasp engines) with supercharger/blower controls? The engine of course only had a single-stage supercharger/blower. I'm asking as I've found a few instances where aircraft with that engine installed have a supercharger/blower "On/Off" lever among the engine controls/throttle quadrant. One of these being the Lockheed Vega 5B "Winnie Mae" NR105W and another being the Amelia Earhart Lockheed Vega 5B NR7952 which made the solo trans-Atlantic flight. Both of these aircraft are described as having R-1340-C engines installed (to the -C1 spec in particular), with single-stage superchargers. I've never come across an aircraft where, with only a single-stage supercharger, there would be a control in the cockpit. Therefore, I'm curious to figure out what the purpose of the supercharger/blower lever may have been - especially being marked "On/Off" - such as in being able to engage/disengage the blower drive(?). I have read where, initially, the primary function of the blower was just to improve mixture distribution, prior to the modifications in the blower section gearing/ratio that would increase the performance of the engine as well.

Earhart's Vega:


"Winnie Mae":


The same setup can also be seen on Lindbergh's Lockheed Sirius:


The original Vega at the Henry Ford Museum also has the same supercharger/blower control: https://www.thehenryford.org/collection ... =gs-184974

Re: R-1340 "Wasp C" With Supercharger Control?

Fri Jun 01, 2018 9:41 am

John: I have a friend that is probably the formost expert on Lockheed singles. I’ll drop him a note when I get home later today and ask him. He might even pop in here, as I think he has been on the board before.

Re: R-1340 "Wasp C" With Supercharger Control?

Fri Jun 01, 2018 5:23 pm

That would be fantastic!

The closest I've ever gotten thus-far is there is mention of an on/off supercharger lever in a 1949 P&W engine manual, but it is in reference to a turbocharger/turbosupercharger setup, which I've never heard/seen reference to in the case of any Lockheed Vega.

Re: R-1340 "Wasp C" With Supercharger Control?

Mon Jun 04, 2018 1:14 pm

John: Here is what I got by from my friend:

Clueless here

The old parts books and op manuals discuss non floating and floating drives, talk about safety clutch on some - but make no mention at all if PIC had any control over such things

There were 5:1, 7:1 and 10:1 drives

I suppose its possible that one could NOT have impeller rotating at all? (normal aspiration)

After all, these were not high output engines like were being built 10/15 years later

I don't have any of my copies of Revolution in the Sky, by Allen, here at the house, but I think I can lay my hands on one over in storage this next weekend. It may have something on the controls in it.
Best I can do for now....

Re: R-1340 "Wasp C" With Supercharger Control?

Mon Jun 04, 2018 6:13 pm

Thank you, I appreciate it very much! I know it was a real transitional time period, the very late 20's/very early 30's, with these engines.

Re: R-1340 "Wasp C" With Supercharger Control?

Tue Jun 05, 2018 1:11 pm

Some radials, don't recall which, had an impeller for evening out the mixture distribution only, not supercharging.

Cvairwerks wrote:I suppose its possible that one could NOT have impeller rotating at all? (normal aspiration)

Re: R-1340 "Wasp C" With Supercharger Control?

Wed Jun 06, 2018 3:07 pm

John, just a guess here, but Wiley Post wore a pressure suit for his altitude records. It is likely that the pressure would have been derived through an engine-driven blower, and it would have to be separate from the stock supercharger. I guess one question that might be answerable was did Lindberg use a pressure suit at some point with his Sirius.

The quadrant has both a supercharger and "blower" control. We know what the superharger is for and by the way, I would bet they had something more than a standard single speed supercharger. Getting to 50,000 feet is no small task Especially as it appears they were using a fixed pitch prop! So, what is a blower for since it is not a supercharger? Either has to be a turbocharger or a compressor for the pressure suit. Or both.

Re: R-1340 "Wasp C" With Supercharger Control?

Thu Jul 12, 2018 8:46 am

[duplicate deleted]
Last edited by tailspin45 on Sat Jul 21, 2018 9:16 am, edited 2 times in total.

Re: R-1340 "Wasp C" With Supercharger Control?

Thu Jul 12, 2018 8:48 am

Just discovered this thread and have been puzzled by the "B" lever, too. There are some artists and magicians at wing42.com that are building a digital replica of the Vega 5C that will be the most authentic simulation ever created--they're even creating an algorithm that models heat transfer within the engine so that oil temps and CHT, etc, will respond to how hard the engine is pushed. Their thread on this topic is remarkably similar to what I'm reading here.

Our working theory is that the early 1340s had a mechanical clutch between the crank and supercharger that was later replaced by an internal spring clutch and then a leaf clutch typical of the WW2 1340s

I’m headed down to the San Diego Air & Space Museum this morning where the librarian found a 1929 R-1340-C manual. Dunno what it will reveal but report back here. Meanwhile, an engine guru at the New England Air Museum is going to inspect their rare 1340-A and let me know what he finds. I'll share that too, of course.

Our understanding is that Wiley Post's "Stratosphere" Vega had a mechanical supercharger sitting up above the engine with either a chain or belt drive. That, we assume, would be controlled by the second blower knob.

Re: R-1340 "Wasp C" With Supercharger Control?

Fri Jul 13, 2018 2:03 pm

Been searching for exactly the same information‚ so similar that I wonder, John, if we already know each other but by screen names (Tailspin45).

Anyhow, I found the answers, clearly spelled out in a 1929 P&W Wasp Series C Engine Manual the San Diego Air & Space Museum holds.

Went down yesterday and used iPhone to shoot some of the pages. The images are at http://forum.wing42.com/viewtopic.php?f=6&t=815

The early Wasps did indeed have a mechanical clutch. It was later replaced with an internal; spring-clutch and then by a leaf clutch.

As someone else here notes, Wiley Posts "Stratosphere" Vega also had an external, mechanically driven supercharger mounted up on the glare shield in front of the windscreen. There was a separate, second lever to engage that blower.

Off topic a bit, but Walter Bowe's Vega, Dolittle's in Shell Oil colors, flew for the first time since 1954 about a week ago! Woohoo!
Last edited by tailspin45 on Sun May 05, 2019 11:36 am, edited 1 time in total.
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