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View Full Version : WARP DRIVE: Square or Taper Tip



SkySteve
01-10-2015, 06:05 PM
OK, boys and girls, I need your input. I'm currently running a 3 blade square tip WD in front of my 912 80 hp Rotax, but I'm thinking very seriously about sending the blades to WD to have them cut the blades into Taper Tips and add Nickel leading edges. I'm thinking I'll get higher RPMs for stronger/shorter take off and an increase in cruise as well. Am I thinking smart or foolish? Let the opinions roll ...

Av8r3400
01-10-2015, 06:25 PM
From everything that I have read, a 68", three blade, square tip, Warp Drive prop exceeds the MMOI* rating on a Rotax gearbox. Tapering the tips, including the nickel edge, brings it back to the acceptable, yet still at the max, rating.


*MMOI - Mass Moment of Inertia.

http://www.aviasport.com/Rotax/Documentacion_4T/Instrucciones/Ingles/11ul91.pdf

http://www.eaavideo.org/video.aspx?v=2010764613001

Dave S
01-10-2015, 07:36 PM
Steve,

FWIW - I have used a tapered tip nickle edge warp from the beginning on our plane - and, the nickle edge has done quite well for durability.

The Nickle edge was primarily designed for float planes to reduce the erosive effects of water spray on the prop - I ended up with the nickle edges simply because it came with the prop I got - but I do like it - so far no nicking or dents other than inconsequential/minor.

Sincerely,
Dave S
KF 7 Trigear

WWhunter
01-11-2015, 08:16 AM
What are your thoughts on a 2-blade verses 3-blade?
Reason for the inquiry is I had a 2 blade Warp Drive taper tip on my 912 but it seemed to have a high frequncy 'buzz/vibration' at higher RPM. I got very good performance from the prop but changed out to a 3-blade.
Now that I have a Kitfox that needs a prop I was thinking of using it due to everyone's suggestion to sh!tcan the GSC.

SkySteve
01-11-2015, 10:20 AM
When I was looking for a new prop several years ago my A&P told me I would get better performance (for my application) from a three blade. It has done a great job. I fly with a guy who flies a Bearhawk with a 2 blade. He has just changed over to a 3 blade MT prop. Most of our landings/take offs are off airport.

WWhunter
01-11-2015, 10:28 AM
Steve, I have heard both sides of the 2-blade/3-blade arguement. Generally floatplane guys say that a 2 blade has more 'pull' and the 3-blade guys states smoother running and more speed due to less disk area. Heck, I am a lowly GA guy that is just in search of more info.
I know I did lose a little in T/O performance when I went to a 3 blade but, oh....my engine is so much smoother now. The difference wasn't huge but definitely noticable.
The other reason I swapped out was the fact that I will be installing the floats (eventually) and need a prop for seaplane use. The Warp, although a taper tip, was without the leading edge protection. I bought a Whirlwind with nickle leading edge and am happy with it on my RANS.
The WD is like new with very few hours on it so I may as well find a use for it. I'd lose too much trying to resell it.

SkySteve
01-11-2015, 02:13 PM
WWhunter,
I have heard both sides of the same argument, too. I am NOT a prop guy nor an engineer so I have no idea what the truth is. My best guess is...it depends. That's why I just went with what my A&P said. I'm happy. Still rather ignorant, but happy.

jrevens
01-11-2015, 02:55 PM
Theoretically, the fewer the number of blades the greater the efficiency. I think it has to do mainly with how much "disturbed" air each blade encounters from the blade that precedes it. It was well known by model builders that the most efficient set-up was a single blade prop with a relatively small counterweight on the other side of the hub. There are many other considerations of course. Propeller ground and/or structure clearance while still being able to utilize existing horsepower is one issue. I believe that under ideal conditions and everything else being equal, the best 2-bladed prop for a particular situation will outperform the best 3-bladed one based strictly on available thrust. I'm going to use a 3-blader for esthetics, ground clearance, and perhaps some other minor benefits.

SkySteve
01-11-2015, 03:03 PM
John,
Your point about ground clearance is probably one my A&P was considering as I am flying a tri gear off airport.

So, any additional opinions regarding the Square tip vrs the Taper tip? Going, going, almost gone.

JimS
01-11-2015, 03:42 PM
I'll jump in with my 2 cents.
Updated my Model 4 to a 80 HP UL with the wide tip Warp (replaced my 582). Had a vibration I didn't like from about 4000rpm on up and then I read an artical by Paul Lipps (?) where he detailed the lost performance of wide tips on props. (Reno racers run a lot of his props). Anyway, I sent mine back to Warp, had the tips tapered, got rid of 80 % of that nasty vibration, and got a bit better performance to boot.
JimS

Norm
01-13-2015, 08:04 PM
Is it a two blade or three blade warp.

JimS
01-14-2015, 06:05 PM
It's a CHREE Blade. (FAA controller talk):D 3 blade for the rest of us.

JimS

Norm
01-15-2015, 06:20 AM
Thanks for reply. I have a two blade that has much better performance than my IVO but with a nasty vibration I won't live with, I have considered sending it back to have it tapered.

SkySteve
01-19-2015, 09:13 PM
Shipped my square tip Warp Drive to Iowa to have it cut to Tapper Tip and install nickel leading edges. Looks like I'm grounded for about 3 weeks.
:( , then :D

DesertFox4
01-19-2015, 10:04 PM
Sorry to hear that Steve. If I had a spare Ivo, I'd send it to you or better yet, come down and fly with me.

SkySteve
01-20-2015, 06:39 AM
Thanks, DF4. Both sound like great options.

SkySteve
02-03-2015, 05:00 PM
Received by newly cut Warp Drive Taper Tip propeller yesterday. Installed it today. I set it at the same pitch as before I had it cut and did a run up. I gained 300 RPM Wide Open Throttle. The weather was crappy and time was short so I didn't test it yet. Within the next few days I'll do some take offs and cruise testing and let you know how it goes. So far, it does exactly what Daryl at Warp Drive said it would do. :)

kitfox5v
02-03-2015, 05:44 PM
Steve,
What pitch are you running and what engine?

Thanks Eddie;)

SkySteve
02-03-2015, 07:08 PM
The engine question is easier than than pitch. The engine is a Rotax 912A. 80 HP. The pitch is 11 degrees at the tip. I checked it at the inside edge of the nickel leading edge, closest to the attach point and it is 22 degrees there. I hear all kinds of pitch degrees and have never really understood at which point people are setting pitch. My plane is 660# empty and I have 8.00x6.00 tires. Before the tapper tip I could get off the ground, on pavement, with just me and full fuel in an easy 300 ft. It would cruise at 100 mph but preferred 90-95 mph. My Wide Open Throttle during run up was 4,800 rpm. Now it's 5,100+. If I can get a nice cruise at 95-98 mph I will take a little pitch out for shorter take off.

kitfoxnick
02-03-2015, 08:20 PM
If I can get a nice cruise at 95-98 mph I will take a little pitch out for shorter take off.
I think you should be able to get that. I have mine set at 11.5 deg at the tip. My model 4 is a long wing taildragger has 26" bush wheels, and I see 105 at 5200rpm 96-98 at 4800.

SkySteve
02-03-2015, 09:33 PM
Thanks, Nick. Good info.

av8rps
02-04-2015, 09:13 AM
I think you should be able to get that. I have mine set at 11.5 deg at the tip. My model 4 is a long wing taildragger has 26" bush wheels, and I see 105 at 5200rpm 96-98 at 4800.
But Steve's Kitfox uses the older, much slower airfoil. So he will probably never get a high cruise speed like your Model 4. I was actually surprised to hear he was getting a cruise speed as high as he does.

SkySteve
02-04-2015, 11:55 AM
Hey there, av8rps. Watch who you're calling O-L-D!! :) I've set my VNE at 100 mph and may have exceeded that a few times. No flutter, but I wouldn't want to push it past that. But you are right, ol' 85DD is a cruisin' maniac!! :eek:

DesertFox4
02-04-2015, 05:33 PM
Something for Steve- just in case you hadn't seen it before. That Warp prop would work nicely on this rig.;)

8407

SkySteve
02-04-2015, 06:00 PM
DF4, Now that's a good areoplane! Some lucky guy has probably hung a tapper tip warp drive on it by now! And, no, I haven't seen that. Thanks!!

DesertFox4
02-04-2015, 08:13 PM
Thought you might like that Steve. That little airplane sold a ton of kits.:)

It think it would look good with some Aerocet 1100 amphibs. Just a thought.

SkySteve
02-04-2015, 09:52 PM
You just might be right, just might be:

http://i237.photobucket.com/albums/ff12/KitfoxSteve/85DD/21bf6549.jpg (http://s237.photobucket.com/user/KitfoxSteve/media/85DD/21bf6549.jpg.html)

http://i237.photobucket.com/albums/ff12/KitfoxSteve/85DD/1952B88B-F4F2-42C1-882B-8D1988DBA355-1579-0000014C2D8B5153.jpg (http://s237.photobucket.com/user/KitfoxSteve/media/85DD/1952B88B-F4F2-42C1-882B-8D1988DBA355-1579-0000014C2D8B5153.jpg.html)

SkySteve
02-11-2015, 07:17 PM
I was able to fly the new Warp Drive Taper Tip propeller today. I installed it at 11 degrees measured at the blade tip, same as with the square tip. On the ground run up, the rpms increased 300 rpm, from 4850 to 5150. My plan was to do several stop and goes but there was just too much traffic today, so I did several T&G's then some straight and level flight away from and back to the airport. Take off was very smooth and seemed to be shorter than normal but I was only able to make one take off from a stop. During several T&G's I noticed it was difficult to slow the plane down on final. I usually come over the fence about 50 mph with a touch down speed between 38-40 mph. Today I had a hard time slowing down over the fence much below 60-70 mph, resulting in float at the threshold where I normally touch down. When I left the airport the wind picked up a bit and was choppy, but I did notice that with a little power added, the prop spooled up quickly, taking me over 100 mph in just a moment. Much faster spool up than with the square tip. I finally found some smooth air to test cruise speed (just me on board and 1/2 tanks of fuel [about 6 gals]). I normally like to cruise at 5300 rpm which gives me 93-95 mph with a 3.5-3.7gph fuel burn. With the square tip I can get 98-100 mph at 5400-5500 rpm at 4.2-4.5 gph fuel burn. Today I also cruised at 5300 rpm which gave a 98 mph cruise speed on the Airspeed Indicator and GPS. Fuel burn was 3.7 gph. All in all I'm pretty happy with the results. I'll try again tomorrow or the next day to get more data.

Dave S
02-11-2015, 08:28 PM
Steve,

Sounds like a great first experience with your re-configured prop.

Early on I had a similar deal with the plane's reluctance to slow down on short final. Diddling with the pitch changes that but not necessarily in agreement with optimum climb or cruise. Originally I the set the idle speed at 1800 on the ground - that gave me approx 2300 rpm with the throttle closed & gliding @ 65 mph. I set back the ground idle 200 RPM and that resulted in 2100 rpm @ 65 mph glide with the throttle closed and allowed the plane to slow down over the threshold more easily. I then adjust the throttle on rollout so the RPM ends up @ 1800 when I stop.

Thinking what this has to do with is if the speed is low (like 65) the prop is still either 1) making some thrust at a "normal" idle speed for a particular prop pitch or 2) not producing enough drag at a "normal" idle speed for a particular prop pitch. By reducing the RPM some of the thrust goes away or the drag increases. I have thought about coming up with some sort of measurement system to determine what the "zero thrust" @ RPM & MPH would be for a particular pitch; but, haven't figured out any novel way to measure that yet.:confused:

Sincerely,

Dave S
KF7 Trigear
912ULS Warp Drive Tapered

SkySteve
02-11-2015, 08:53 PM
Dave,
Good thoughts. I have my idle set slow, also. I can't remember right now what it is set at, but I think i set it all the way back to 1100 rpm. Of course, I only use that on final to slow down. I normally idle at 1700-1800 rpm on the ground. I'm thinking the propeller mass has been reduced enough that I'm not as draggy as I used to be on final. On final I use the stick (attitude) to control speed and the throttle to control rate of descent, adjusting throttle on the glide slope to hit my predetermined touch down spot. I'm thinking my hand muscle memory may be over-riding my brain! I'll work on it within the next couple of days and see what I can do. Thanks for your input. It caused me to think again.

jtpitkin06
02-28-2015, 09:44 AM
Something for Steve- just in case you hadn't seen it before. That Warp prop would work nicely on this rig.;)

8407

Interesting that the aircraft in the Private Pilot magazine ad has outlived VHS, BETA and "reader service cards".

John Pitkin