Cross-category Static Thrust Competition
There will be a cross-category Static Thrust Competition at:
April 3-6,
Bensen Days, 40th Annual
Wauchula Fl
Static thrust competition - Gyros, Trikes, PPCs, Airboats, PPCs, FW welcome
http://www.bensendays.us.com
http://www.bensendays.net.
In preparation, I Static Thrust tested my four trikes today. My gyro is at another airport and I will test it later. Here are my results:
Rotax 277, 58” PowerFin, 2-blade = 200.2 lbs
Rotax 447, 68” Ivo, 2-blade = 300.6 lbs
Rotax 503, 70” PowerFin, 3-blade = 400.7 lbs
Continental A75, Warp Drive, 3-blade = 350.3 lbs
In summary, I was very happy with the Rotaxs but did not expect a lot out of the A-75.Warp. I've been shopping for a better prop for a while.
Out of curiosity, what are your results?
I’m posted this to try to generate some interest for a Static Thrust Competition at B-Days.
Typically you compete with others with the same engine…the props, carbs, re-drives and engine compression are the key variables.
Although static thrust does not tell the whole story, the resulting data does tell part of the story…plus this is great fun.
Comments
Can you tell us how you set up the test?
In response to a question:
We will use a “Y” bridle with each rope end making two wraps at or near each axle and use a bowline knot. This avoids any potential damage or rope slippage. FW use the tail wheel or mains (with tricycle gear), like the other aircraft. Never had a problem.
It’s expected to see 200lbs to 900lbs. We can go to 1,200 for any unlikely person fortunate enough to have that kind of thrust.
Also note the dynamometer has a memory needle so you never need to get beside or behind the prop. The pilot can be in or out of the aircraft, whichever is easier to manipulate the throttle and switches.
I do mine by myself outside the aircraft with my hands on the throttle and near the switches.
Wow, this is cool. Can't wait to see the results. How much does prop pitch play into the equation? Do you re-pitch for the static comp? or just test in the configuration you fly?
you know what else would be interesting would be to get a sound meter to award the quietest thrust winner also. So many airports are noise sensitive.
Hope some electric trikes / planes show up to the comp!! ;)
I have my stock configuration of 80HP Rotax 912 UL with an Arplast 3 blade prop- not sure what the prop diameter is.
Hey good idea, the organizers just polled the forum for activities and comps. Quietest...yes. Mine won't win that’s for sure. I test them as I fly them. I'm in search of empirical data…and the “perfect ride.”
Just looking around on the googlesphere and WOW Those dynamo meters are some spendy beasts. Is there such thing as an affordable one?
@MontyStone showed one once he rigged up with a simple weight scale meter with a memory needle on it. It was great low tech ingenuity.
Monty replied by email to me: "hi xc, the scale was a game scale, $20 on internet, i made the 'tell-tale out of scraps. it works good. i was surprised to find that it took 50# thrust on damp grass just to get my trike to roll (no eng). on blacktop it ' only'took 25# to move it. also the readings varied greatly with max rpms versus cruise."
I always do mine on concrete or wood planks. Plus obstructions in the back have an affect...free vortex in the flow field, etc.... essentially OGE (Out of Ground Effect) compression type phenomenon.
Looking forward to the results of this comp April 3-6. Let us know what happens CBurg
Click on Image to view
By the time static thrust testing took place at 11am Saturday morning, warm temperatures had pushed the density altitude to 6,400 feet. Six participants submitted their machines for testing. The results (in pounds of thrust, top of page) include an estimate ("ISA") of equivalent thrust at sea level under standard conditions (15oC, barometer 29.92).
http://www.utahrotorcraft.org/WR/Western_Rotorcraft_2013_07_hires.pdf
Contributed by @Cburg