Sting Airplane Performance with DUC Swirl Propeller
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- Опубликовано: 26 сен 2024
- Take-off, climb, and cruise performance of the Sting light-sport airplane with the DUC Swirl propeller.
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Outfitting my Sting Sport airplane with this propeller was the single most important thing I have done to improve performance and overall flying enjoyment in the 3.5 years (1,200 hours) I have owned the airplane!
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Soundtrack: "Bollywood Dreams (Vocal Version)," by agcnf_media. Royalty-free license purchased through pond5.com
Loved this video, and the camera angle you use for the in-cockpit 1st person view. Keep these type of videos coming!
Yeah, the cardboard box strapped to the chest isn't exactly high tech, but it worked--way back when I did this video!
Note in the video that 120 SNL (straight-n-level) knots airspeed (the light-sport airplane speed limit) at 2,500 MSL, is achieved at 5,200 RPM. Maximum sustained cruising RPM for this Rotax 912ULS engine is 5,500, which, if you want to ignore speed limits, would pull the airplane at about 130 knots. And if you were to bury the throttle, SNL, you could pull about 140 knots! All this, with a pitch setting that gives the takeoff climbout performance shown in the video!
I saw the same prop on an Aerospool WT9 Dynamic here at VCB.
great video, lots of useful info!
Thanks, Dudu!--As the former and first owner of this wonderful little airplane, you should know!
I did notice a significant reduction in rpm as the plane left the ground. I have a Duc too and I am seeing 5380 on take off roll and then 5200 climbing,
Those are good numbers. Currently, with 3,050 hours on the engine, at sea level, 65 F, I get 5170 rpm on climb-outs, pitched at 23.3 degrees. And this beauty of a Sting, with lots of life left in it, and thousands of dollars in spare parts, is currently for sale (not listed, yet) at $38K. Pass the word. Thank you.
In the three years of Sting ownership, I have not changed the setting on the blades of the wood comp which was set by the prior owner's mechanic. Two of the three blades were replaced prior to my delivery so I am on almost new blades. Do you notice any loss of thrust on go round or climb rates, from low to max power settings.
The short answer is no--as long as you throttle up smoothly and slowly (~2-5 seconds). Just don't jam the throttle straight on. The blades need time to bite--then they bite even more! See my "downside" comment, below, also.
Very nice! So that had a pretty significant improvement then... Just gonna take some time to settle in with it, then?
Roger that...
The Duc Swirl is a piece of work. I have the wood comp OEM on my '06 still. What is the cost of change?
Aircraft Spruce cost~$2,000 for prop and all-carbon hub; Not sure of cost through Sportair USA. Any needed spacer, spinner, and bolts, add a bit to that. I was able to use my old spacer and spinner, and only needed 6 new, slightly longer M8 bolts. I would never bolt either of the two old, Woodcomp props I have--back on.
Sting Flight...At least not now that I've seen what a smooooth rocket the DUC turns the Sting into!
Sting Flight There is a downside to this prop that everyone should understand, however: Cavitation if you power up too quickly! You need to smoothly and gradually apply power during your takeoff roll; jamming the throttle on is counterproductive, leaving the airplane just sitting...Also, that's why Short Field procedures with brakes on/power up/then brakes off, are also counterproductive.
what type of attitude indicators do you have?
they show a pretty steep bank when you're turning while taxiing onto the runway.
that doesn't seem ideal...
They are both Tru-Traks. The upper one, tied to the GPS & Auto-pilot is not functional until the airplane lifts off and/or hits a certain speed on roll-out.
I'm not sure that you understand that once an aircraft is off the ground, the headwind disappears relative to the ground. Your climb angle will be affected by the headwind because that is vertical climb relative to the distance you cover over the ground, which is less (the distance) due to the headwind. Feet per minute is relative to time, which cannot change due to headwind, only due to a change in angle of attack or airspeed. If you couldn't see outside of the aircraft, you would not even notice an increase in climb angle because you would have nothing on the ground to confuse your brain.
In other words, a constant wind can never affect climb rate per time (FPM) no matter where it is coming from.
Glass Cockpit Aviat
I put a new DUC Flash propeller on my Sting S3, but am not sure the pitch is set correctly. I only get 4960 rpm on takeoff and climb, suggesting it is too coarse, yet the cruise performance (100kts @ 5000 rpm, 116kts @ 5400 rpm) would suggest the pitch is too fine. Any suggestions?
Brent Oster I haven't tried the Flash. But, with my Swirl, I get 5100-5200 on climb-out at 60 kts. The steeper the climb-out, the more rpm it pulls. Whether this is due to "bitting" more air, or cavitation, I don't know. But I know the Swirl is very sensitive to all three blades being perfectly the same pitch; In my opinion, achieving this necessitates a good digital protractor--not just a simple "level" protractor. Also, on my Sting Sport, I found the perfect pitch to be 22.3 degrees, not the 23 DUC recommended. I would check the climb-out at 60 kts and if I was still under 5000 I might try some adjustments to pitch--and re-check all blades are the same. Don't forget, temperature, altitude and humidity come into play, too.
Sting Flight PS: Setting pitch requires carefully measuring and marking where you place the digital protractor, because even tiny changes of location along the blades give different measures of pitch, due to the twist of these blades along their length. I mark the measure points of all three blades first, with masking tape, before even thinking of putting the protractor up there. And I clamp the protractor onto each blade, never just holding it against the blade for a measurement!
Sting Flight Sorry, I'm getting too carried away, here. I need to put all this into a video! I've been meaning to for a long time. Now's the time! I'm going to get to work on it. Contact me direct (drdehave) at hotmail.com if you want to discuss this further.
Sting Flight One more thing: There is a definite break-in period with these all carbon props. They loosen up and perform better after some time. For mine, it was about 300 hours, before I felt it was fully broken in. And I noticed gradual improvement all the way to this milestone.
+Brent Oster +Sting Flight I have a new Sting S4 (60 hours) with the DUC Flash. With the prop set to 23 degrees, at 5260 rpm I get 106 kts TAS. I've consulted with a mechanic who is also a DUC dealer who told me that in his opinion the Swirl is a much better prop. That said, the Flash has a 2000 hour TBO and I believe the Swirl is 800. Haven't decided with to do yet but I'm leaning toward moving the prop to 24.5 degrees. If that doesn't work, I'll likely get a Swirl.
Two minor downsides to this prop that I did not have time to include in the video: 1.It tends to cavitate in the static position (thus, standard "short-field" TO practice, running engine up, with brakes on, is actually counterproductive; you need instead to "roll" onto the RW); and 2. There is a definite "break-in" period, of about 25-50 hours.