Tri blade propellers

Here is a basic flight test to show battery life in regular flying here in GPS ATTI and Manual modes this flight, I also fixed up some vibration issues I have been having after a crash a little while back. I had to replace one motor and as I did that I also did a proper motor balance for the first time. They werent that far off but I got them a little better and its probably the smoothest it has ever got.

Using default battery levels in NAZA I got 10 minutes flying my FPV setup with these triblades and a 2700mah battery all up weight was 1157g. Stability is pretty nice too and this wasnt just hovering as I flew around the neighborhood covering a couple km at least in the flight but I dont know exactly. Using a 2200mah battery I can do 8 1/2 minutes with this setup and it even lifts my 3D setup at around 1300g fairly easily with good run times only about a minute shorter with the same type of flying.

[youtube]http://www.youtube.com/watch?v=ShtVGPx09KA[/youtube]
 
Mine are GWS 9050x3 bought from here http://www.multiwiicopter.com/products/sku-27 as I am in Australia and these are 2 full sets pretty cheap. I have also seen them at Hobby King and other online stores but if you do order them make sure you are getting CW and CCW props as some places sell them as a pair but they are a pair in the same rotation.

For my motors I didnt have to do anything as I have round 5mm prop shafts and these have 5mm spacers that fit perfectly, for stock DJI motors you would need to ream them out to 8mm, a few other guys have done so and are using them on stock motors without issues.
 
Skylane765 said:
bumper said:
Sometimes it's necessary to eat crow (even though it doesn't taste all that good unless battered and deep fried :c)

Okay, I've ordered the GWS 9050 on eBay to test. Considering the testing other's have done, bigger prop "rules" may not apply.

BTW, after spending $10,500 for just one 2-blade MT prop for my Husky :shock: , these tri-blade props seem quite a good deal.

bumper
That is fixed pitch on the Husky? Try $35,000 for the 182T

No, the Husky A1-B has a constant speed prop, the $10.5K was the total and included an optional "chrome look" composite spinner.

BTW, just did a flight time test comparing these tri-blades

http://www.ebay.com/itm/350783228590?ss ... 1439.l2649

to these CF 2-blades

http://www.ebay.com/itm/281114870038?ss ... 1439.l2649

Same battery, similar conditions, still air, 70F, hovering at 4850' above seal level.

I wanted the 2-blade to win as it's easier to deal with in storage (fits in case), but it only got 8 minutes 5 seconds to self induced landing with red light flashing, while the tr-blade made it to 8 min 38 seconds. This was also no additional cargo or electrical load except for the FPV Tx, which wasn't powered, and the 120 ma LED headlight which was. Battery discharge limits were default.

So, the pain in the butt tri-blades are the best so-far. I may try to find a longer CF 2 blade with a bit more pitch for the altitudes I'm flying.

bumper
 
bumper said:
Skylane765 said:
bumper said:
Sometimes it's necessary to eat crow (even though it doesn't taste all that good unless battered and deep fried :c)

Okay, I've ordered the GWS 9050 on eBay to test. Considering the testing other's have done, bigger prop "rules" may not apply.

BTW, after spending $10,500 for just one 2-blade MT prop for my Husky :shock: , these tri-blade props seem quite a good deal.

bumper
That is fixed pitch on the Husky? Try $35,000 for the 182T

No, the Husky A1-B has a constant speed prop, the $10.5K was the total and included an optional "chrome look" composite spinner.

BTW, just did a flight time test comparing these tri-blades

http://www.ebay.com/itm/350783228590?ss ... 1439.l2649

to these CF 2-blades

http://www.ebay.com/itm/281114870038?ss ... 1439.l2649

Same battery, similar conditions, still air, 70F, hovering at 4850' above seal level.

I wanted the 2-blade to win as it's easier to deal with in storage (fits in case), but it only got 8 minutes 5 seconds to self induced landing with red light flashing, while the tr-blade made it to 8 min 38 seconds. This was also no additional cargo or electrical load except for the FPV Tx, which wasn't powered, and the 120 ma LED headlight which was. Battery discharge limits were default.

So, the pain in the butt tri-blades are the best so-far. I may try to find a longer CF 2 blade with a bit more pitch for the altitudes I'm flying.

bumper

I bought the same tri-blades. Didnt realize they needed to be notched or something to get them on. What did you use?
 
fizzviic said:
I ran across this yesterday on another site. Very interesting. Seems to contradict most thinking on the subject.

http://youtu.be/hYr3a8b85r4

Well done video. Unfortunately, there are a number of additonal prop design parameters that will skew the results. Basically, all else being equal (and it seldom is), the fewer the blades a prop has the more efficient. Efficiency also increases with diameter and with reduced RPM. Varieations in blade airfoil and tip design are a significant factors as well.

Bigger, slower turning, less blades, then throw in all the compromises necessary to make it fit and work!

bumper
 
fizzviic said:
I ran across this yesterday on another site. Very interesting. Seems to contradict most thinking on the subject.

http://youtu.be/hYr3a8b85r4
Although the author gets high marks for his apparatus, the experiment is rather poorly defined. He compares a 9" tri-blade to an 8" bi-blade. This really yields no useful conclusion. He should compare same diameter blades to determine what the thrust is for a given amperage draw (tri should be less thrust for the same current) as well as what is the max thrust achievable (tri should provide more thrust).
 
If the test is to compare max *static* thrust with the number of blades as the only variable, then diameter, pitch, and airfoil of the props under test will also need to be the same.

The engine, or motor, and prop combination will behave differently when static testing, or hovering, as compared to dynamic testing, with the craft moving. For a fixed pitch prop (not variable or constant speed) it takes more engine power to turn the prop when the craft static than when it's is moving.

In aircraft, just considering number of blades (all else the same), the fewer the blades the more efficient. So if that's the case (and it is!), why even have 3 or more blades? The answer is really simple in aircraft, during WWII as engine power increase in the effort to maintain air superiority, they quickly reached a practical prop length limit for ground clearance. Prop efficiency took a back seat to the need to harness more horsepower, thus 3 and more blades, wider paddles, and even counter-rotating props where used towards the end of the war.

Now in GA aircraft 300 hp and up is about the point where a 3 blade makes sense.

bumper
 
Yep. ..And it appears the the phantom is in a similar boat ( limited by ground clearance - or rather, nearby prop clearance). IOW, it wants more blade but cannot fit the optimal size with a 2 blade prop.
 
That's right, and at higher density altitude, one needs even "more prop" with the Phantom than when it's cooler and down closer to sea level. Going back to prop aircraft examples ('cause that's what I'm most familiar with) his would not necessarily be so apparent with a normally aspirated gas engine turning s prop, as the internal combustion engine loses about 3% power per thousand feet of altitude. Not so with an electic motor that doesn't care about altitude. So, almost like in WWII, we are looking for ways to harness the power efficiently and with limited clearance.

The 9 X 5 plastic 3 blades I tested were good, but I think due to their very flexible thin plastic blade design, give away some of the bite they would otherwise have as compared to a stiffer prop. Haven't been able to source cheapo 3-blade CF's, so have ordered some bigger CF 2-blade props, 9 X 4.7, and will see how those do. Summer time density altitude here is almost always over 7K and often over 9K feet on the valley floor.

bumper
 
I'm going to stick with the 9X5 tri-blades for now. My Phantom just seems to have (for lack of a better term) more zip!
 
So, would a carbon fiber TRI blade work better at lift? I'm
Not sure I've ever seen one that would work with the phantom.

On that note, the tri blades I purchased from ebay aren't notched like the stock. I know someone said I could just drill them out to fit and add the spacer, but without the notch doesn't it just spin inefficiently?
 
Glockindahaus said:
So, would a carbon fiber TRI blade work better at lift? I'm
Not sure I've ever seen one that would work with the phantom.

On that note, the tri blades I purchased from ebay aren't notched like the stock. I know someone said I could just drill them out to fit and add the spacer, but without the notch doesn't it just spin inefficiently?

you might have to add a spacer, but once you do that,. be sure to clamp it down good and it should work ok.
..and be sure to check the nuts prior to flying each time.
 
Glockindahaus said:
So, would a carbon fiber TRI blade work better at lift? I'm
Not sure I've ever seen one that would work with the phantom.

On that note, the tri blades I purchased from ebay aren't notched like the stock. I know someone said I could just drill them out to fit and add the spacer, but without the notch doesn't it just spin inefficiently?

you might have to add a spacer, but once you do that,. be sure to clamp it down good and it should work ok.
..and be sure to check the nuts prior to flying each time.
 
After installing the 8mm spacers in both props, I had to very carefully remove some material with half-round a modellers file. The fit was just too tight to even "force" them on the motor shafts. I filed until the fit was about the same tightness on the shafts as my stock props. To be safe, I put star washers under each prop nut. and the last item on my pre-flight checklist is "torque the prop nuts".
 
Glockindahaus said:
So, would a carbon fiber TRI blade work better at lift? I'm
Not sure I've ever seen one that would work with the phantom.

On that note, the tri blades I purchased from ebay aren't notched like the stock. I know someone said I could just drill them out to fit and add the spacer, but without the notch doesn't it just spin inefficiently?
If the cap nuts are tightened properly there should be no slip. It is a tight fit - so I let the nut push it onto the shaft rather than trying to push them on with my thumbs.
 

Members online

No members online now.

Forum statistics

Threads
143,066
Messages
1,467,358
Members
104,935
Latest member
Pauos31