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

Yes. That would be correct. The fact is though most dynos run tractor props so they can provide air to the heat exchangers. We have run Steve's for over an hour to test heated operation power and for that you need a good radiator and oil cooler.

Bill Jepson

Bill are you in the Portland area?

Paul Lamar

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