Author Topic: Atlas/Thor Vernier Engines  (Read 9907 times)

Offline Danderman

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Atlas/Thor Vernier Engines
« on: 09/13/2013 03:37 pm »
These 1,000 lb thrust engines were produced in the hundreds, and used on early versions of Atlas and Thor. Today, these are common collector's items, and also it is not uncommon for wannabe rocketeers to buy these from surplus outlets for use in amateur rockets.

I have encountered many of these in the hands of rocket groups planning to launch high altitude rockets, but actual flights are rare.

This topic is about the history, the characteristics and the usage of these engines.

Offline DMeader

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Re: Atlas/Thor Vernier Engines
« Reply #1 on: 09/13/2013 07:01 pm »
This topic is about the history, the characteristics and the usage of these engines.

Care to provide some?

Offline Danderman

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Re: Atlas/Thor Vernier Engines
« Reply #2 on: 09/14/2013 12:02 am »
http://heroicrelics.org/info/lr-101/lr-101.html

A real good start on the specifications for the engine.

What I am really interested in would be attempts to fly suborbital rockets with this thing.

Offline Julesverne

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Re: Atlas/Thor Vernier Engines
« Reply #3 on: 09/14/2013 04:56 am »
Bob Truax - he wanted such engines to power his Volksrocket.

Offline Danderman

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Re: Atlas/Thor Vernier Engines
« Reply #4 on: 09/14/2013 02:13 pm »
Bob Truax - he wanted such engines to power his Volksrocket.

Thanks for reminding me. The Volksrocket had 4 Atlas vernier engines. I have no idea how the rocket was supposed to maintain control, unless the 4 engines were allowed to gimbal.

Video of a static test firing:

http://neverworld.net/truax/video/VOLKSROCKET.WMV


« Last Edit: 09/14/2013 02:18 pm by Danderman »

Offline edkyle99

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Re: Atlas/Thor Vernier Engines
« Reply #5 on: 09/14/2013 04:17 pm »
My understanding is that the XLR-101 verniers were not fed by turbopumps on Atlas or Thor.  Their propellant feed appears to have come from the start tanks, which must mean that propellants were pressure fed to the engines.  Please correct me if I've interpreted things incorrectly!

 - Ed Kyle

Offline Danderman

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Re: Atlas/Thor Vernier Engines
« Reply #6 on: 09/14/2013 04:26 pm »
My understanding is that the XLR-101 verniers were not fed by turbopumps on Atlas or Thor.  Their propellant feed appears to have come from the start tanks, which must mean that propellants were pressure fed to the engines.  Please correct me if I've interpreted things incorrectly!

 - Ed Kyle

While the main engine is operating, these engines are fed by the main engine turbopump, as they perform roll control or other attitude control. When the main engine shuts down, the engines are fed  by residual tank pressure and perform vernier function. This means that ISP for these engines in their vernier function is very low, since the main prop tanks are pretty much empty during the period of vernier performance.


Offline Danderman

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Re: Atlas/Thor Vernier Engines
« Reply #7 on: 09/14/2013 04:32 pm »
http://rocket.sdsu.edu/rockets

This is the web site for the San Diego State University rocket team. The 2005 event was a rocket launch with a LR-101 powered rocket that suffered engine failure. There is a lot of info on the LR-101 on this page, and it basically tells the story that "free" rocket engines may not be affordable.

Offline Danderman

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« Last Edit: 09/14/2013 04:42 pm by Danderman »

Offline R7

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Re: Atlas/Thor Vernier Engines
« Reply #9 on: 09/14/2013 04:46 pm »
Flometrics used LR-101 to test their pistonless propellant pump concept.

http://web.archive.org/web/20090412003555/http://www.flometrics.com/rockets/rocket_pump/rocketpumptest.htm
AD·ASTRA·ASTRORVM·GRATIA

Offline Danderman

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Re: Atlas/Thor Vernier Engines
« Reply #10 on: 09/14/2013 06:10 pm »
Flometrics used LR-101 to test their pistonless propellant pump concept.

http://web.archive.org/web/20090412003555/http://www.flometrics.com/rockets/rocket_pump/rocketpumptest.htm

Since one of the functions of a turbopump is to provide for greater ISP than a pressure fed system, it would be interesting to learn what level of ISP was generated by the Flowmetrics test.

Offline edkyle99

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Re: Atlas/Thor Vernier Engines
« Reply #11 on: 09/15/2013 01:31 pm »
While the main engine is operating, these engines are fed by the main engine turbopump, as they perform roll control or other attitude control. When the main engine shuts down, the engines are fed  by residual tank pressure and perform vernier function. This means that ISP for these engines in their vernier function is very low, since the main prop tanks are pretty much empty during the period of vernier performance.

O.K., I see it now.  Those lines from the turbopump were kind of hidden on the drawing I had.  It was the same setup on Thor and Atlas. 

Without turbopump feed, thrust must also have been lower during the pure vernier phase.

 - Ed Kyle
« Last Edit: 09/15/2013 01:32 pm by edkyle99 »

Offline Danderman

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Re: Atlas/Thor Vernier Engines
« Reply #12 on: 09/15/2013 11:44 pm »


Without turbopump feed, thrust must also have been lower during the pure vernier phase.

 - Ed Kyle

Yes. Considerably lower.

Offline Danderman

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Re: Atlas/Thor Vernier Engines
« Reply #13 on: 09/17/2013 04:56 pm »
Later variants of the LR-101 were downrated to about 525 lbs of thrust. I don't know why.


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