Paul et al,


     The recent TTC engine run postings, turbo compound threads, and my own
     efforts have started me thinking about an engine test stand and the
     features/performance it should demonstrate.


     Obviously a control/instrument panel would incorporate some of the basic parameters like...


      oil pressure

      oil temp

      engine (coolant) temp

      exhaust temp

      manifold pressure

      air/fuel ratio

      rpm

      throttle position

      fuel flow/totalizer

      time

      hobbs


      throttle

      mixture

      ignition



     What other controls/measurements should be incorporated on a basic level?


     What about on a more advanced, special situation level (e.g. waste
   gate position when testing turbos)?


     Should it be easily transportable?


     And what about safety features (fire extinguishers, kill switches,
   etc.)? What do you suggested?


     Ideally a data acquisition and control system would collect, log, and
   display the data. I use National Instruments LabVIEW software and
   hardware (along with other manufacturers like Omega, Interface, Banner,
   etc.) for such at work. But it looks like other solutions are available
   through some of the systems discussed in postings here. Personally I'd
   prefer to use something available and proven in order to get to the
   engine testing instead of debugging I/O systems (even though I do that a
   lot with NI LabVIEW!!). What is available and what are your thoughts on
   that?  There are many automotive type test stands out there for basic
   run in testing. But I would expect an aircraft test stand to measure
   torque and thrust for a prop generated load. Not too many (none???) out
   there that I saw, but please let me know about any that you know of.


     Is there any sort of "standard" test prop that would be suited for
   initial or comparative testing?


     A DIY stand seems more practical from a cost and achieving desired
   capability standpoint.


     Therefore, what would be a good upper limit of each value to start
   sizing a stand?


      Max engine torque = ?

      Max engine thrust = ?


     Obviously the answers to my questions are very subjective with many
   variables and personal preferences that could affect the answers. At
   this point I'm just looking for some rough initial numbers for the upper
   limits and capabilities that "amateur home builder" folks like us might
   like to see a stand incorporate.


     I think the TTC engine might be representative of such performance
   limits? Yes? No?


     And what are the thrust and torque goals for TTC?


     Is anyone else interested in building such a stand?


     So put on your thinking caps, let your imagination run wild, and let
   me now your thoughts on this matter.


     Looking forward to your responses!


     Warm Regards to All,

     Brad Chubb



     Be careful optimizing thrust. The best static thrust is not the best
   prop pitch for an
     airplane.  Here are some prop dyno ideas.



     Airplanes fly on HP.


      HP = Torque  X RPM / 5252


     If you measure the torque and of course the RPM you know the HP.


     An aircraft engine will increase the RPM until the prop torque
   requirements are met.


     Paul Lamar



   Please note that almost every item mentioned is on the dyno Steve and
   Everett built. One other thing to mention is the flow straightening fins
   behind the prop. They found that the torque readings were being effected
   by prop swirl until they put them on. Only important if you are
   interested in very accurate HP readings. Most of the time relative
   readings are good enough. Get your baseline and you can tell if what you
   did helped or hurt your performance. For someone looking to build a dyno
   I would suggest looking for a used airboat prop in good shape if testing
   for high power. They are usually designed for large V8 power and will
   work for 200+ HP

   Bill Jepson


   Brad,
   Try advertising for an existing test stand no longer being used.
   It may not be perfect, but it is a start.

   Milo


Am I to understand then that a pusher propeller would not affect the torque reading or not
as much as a tractor prop?

Dale Davies

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