whether a prop produces "worthwhile" thrust at 0 forward
speed depends on your application.
Remember the Davis
DA-9 (??) or so, with Ken Schuggert (?) as the pilot? His prop was stalled up
to about 50 kts(?), idling down the runway (because it would make more thrust
idling than at rpm), until it started to bite..
Long take-off roll, but would go like stink once at speed.
For a CH-801, speed is of no concern, acceleration is everything -
static thrust IS getting interesting here!
Yes, I can agree that if we have a target
number to shoot for and we have a means to measure thrust, it would be
meaningful to measure thrust.
But unless you have something you can do
with the results, having the number does precious little.
I assume as a dyno it would be interesting to have a special static
prop to load the engine and eventually it can be used to compare
engines/mods/etc. with this one prop as a baseline. Whether this dyno prop has
any aviation use at all doesn't matter, it puts some serious load on the
engine. How to calibrate this prop is a different question, but just to see,
whether an engine runs better or worse than before it is good enough....
Revmaster has made hundreds of little
2100cc VW conversions over the past decades. Each one was run on a test stand
with just such a test club.
Specifically this one right here:
www.ContactMagazine.com/Issue80/TestClub.jpg
When they bolt it to a new engine, they
should see a certain RPM or there’s a problem.
""""snip"
Ok... I've seen countless little red biplanes hang from their
prop at airshows; certainly the prop is "stalled", and knowing that
the engine/prop combination can produce thrust to counter the gross weight in
order to allow the plane to hover is useful information to this small group of
pilots. But how many of us really need that info?
If that prop is stalled the bird comes down!! Just because the plane
has zero speed, does not mean the prop is stalled.
Ok, now you are splitting hairs. J You know what I meant. In fact, you used the same term in the
second line in the quoted message above to describe a prop that is in fact not
stalled. But if you are going to split hairs, some part of every prop is
stalled at almost every airspeed, except an Elippse, and that’s only when
the plane is going the designed speed at the designed RPM.
Pat