Tri blade propellers

[martcerv]

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).

Thats comparing the props assuming you arent limited in prop size, I dont think there is any doubt that a 3 bladed prop is less efficiant then a 2 bladed prop when comparing a similar lift prop. 8x4.5 tri and 9x4.5 dual will give very similar lift and if you have the option of either then it would be silly to not go the larger dual bladed prop.

But then when looking at a heavy phantom 9x4.5 is still not quite as much lift as you want and 8x4.5 is really limited in lift. 9 inch blades are the max size we can use due to the frame size and design of the phantom. So we then get the choice of 9x5x3 or 9x5x2, I used 8x4x3 on the phantom and these are pretty useless as they were too small and flimsy with no noticeable advantage in lift over 8x4x2 or obviously 9x5x2 props so 8 inch triblades are going to lose over 9 inch dual blades of the same design and pitch.

The 9x5x3 props will be very similar in total lift as 10x4x2 props which is pretty common on a f450 using the same motors as a phantom. These would likely be a better prop then 9050x3 GWS and there are also more options in stiffer 10 inch props whilst we are very limited in the options when it comes to 9 inch triblades.

So using that video as an example it just shows what I think most people already know about dual blades and triblades in terms of efficiancy. But the problem is if your craft is too heavy to be easily lifted by the largest dual blades you can get and so going triblades will have an advantage and I think this is pretty clear in my use and many others that have also tried these particular props on a phantom.

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

I think thats exactly the point when you are limited in blade length then more blades will give you more thrust or lift. If size is no issue have a huge dual bladed prop like a regular heli but when length is limited and you need more lift then getting more blades is the only real option.

Now that v 4.0 firmware has altitude limits preset I will be able to fairly easily do a real world lift comparison of the props I have. I will simply set my altitude limit to maybe 100m and then on a calm day launch from ground to 100m and see how long each takes to get there at full throttle. This should show real world lift differences between props and I will also show throttle position needed to maintain a hover with each in manual mode. Having flown all my props I have a pretty clear idea of where they all are and as I fly lots in manual mode I can easily tell the lift differences between each by the amount of throttle needed to maintain level flight or a hover.

Some props like graupner 8x5's are the worst lift by a long way in my tests and I get less then half the flight time using those compared to stock DJI plastic 8045 props, this is easily seen in less lift and therefore though they may be the most efficiant props I have they get the worst performance and flight time due to very low lift of these. When I first tried those thats when I started realizing that a prop with more lift may end up giving more flight time and performance then what I was currently using. I then moved to 9x5 graupner clone carbons and 9045 carbon DJI clones. The 9045's are clearly better at providing lift but I really wanted to try a larger prop but 10 inches is impossible on the phantom and so I figured it cant hurt to try some triblades. I was unsure about the effect of reduced efficiency vs more lift would work but was quite surprised that the added lift still ended up giving longer flight times vs the more efficient but lower lift dual blades.

The 9x5 graupners are close to stock 8045 props and so I see very little reason in those too other then looking pretty cool. The 8 and 9 inch DJI clone carbon or nylon carbon props easily outdo the graupner profile props on a phantom and you do have a good choice in prop stiffness when using these. I havent flown the 9x7x3 props yet but being quite a bit heavier and higher pitch I dont think they will be that great on the phantom but will see once I test them.

I still prefer to fly 9050x3 GWS props but would love some stiffer versions of these which if well built I think would be a near perfect fit for a phantom. Even DJI has moved to 9 inch props for the vision and phantom v2 as they have realised the 8 inch props are not producing enough lift and using larger props will give better flight performance and battery life once you start upping the weight quite a bit.

 

[Dale Young]

Wind turbines cant be used as an example because they are catching wind instead of being powered to move wind. It isnt really a black science at all. Two blades are more effecient, but 3 blades provide better climb and acceleration. Most times , 3 blades or more are implemented for clearence issues. Since the tips of the prop cannot be allowed to go supersonic, more blades help govern the power available. Kinda like the gears in a transmission. I have planned for some time of fitting mine with 3 bladed props. BTW, Most times, 3 bladed props are quieter also.

 

[orgnoi1]

Interesting topic... one which I want to follow... tagging in

 

[jumanoc]

Tri-Blades provides a lot of climb and SPEED rates.
I tried these blue 9x5 TriBlades with a 2500 mAh vs. 9x5 dual blades, here some data, just for your information:

SCENARIO: Naked phantom, carrying 250 mW VTX and 520 mini cam FatShark FPV and i-GOT-u Data Logger. Calm wind, Normal (non slow) flight. ATTi mode for reach faster speed.

1) Dual Blades: Flight time 14 minutes, Max speed: 45 mph, max climb (ascend) rate: 7 mts/s, motors temp: warm-normal
2) Try -Blades: Flight time 10.5 minutes, Max speed: 58 mph, max climb (ascend) rate: 12 mts/s :shock: motors temp: warmer than dual..

Conclusion: As more climb/speed rates as less flight time and hotther motors, but speedy was shock in FPV goggles !

 

[boat chaser]

With 920 kv motors I get an extra 1:30s with the gws 9050 tri blades compared with any of the twin blades. What motors did you use for your testing jumanoc? Also the tri blades seem to work better if your phantom is over 1150g. My testing weight was 1246g.

 

[jumanoc]

With 920 kv motors I get an extra 1:30s with the gws 9050 tri blades compared with any of the twin blades. What motors did you use for your testing jumanoc? Also the tri blades seem to work better if your phantom is over 1150g. My testing weight was 1246g.

I'm still with stock motors (3 months ago I bought White Antigravity T-Motors and still waiting for a failure in stock motor for upgrade them :lol: ) My stock motors completed 247~ flights (6 minutes average) with gimbal dual camera, tests, agressive flying... only 2 had required to change the bearings !. I do a maintenance (cleaning, hearing for starnge sound, every 20 flight) balanced since begining.

My AUW is 1190 gr.

 

[boat chaser]

Sounds like you have the maintenance pretty sorted on the stock motors. I personally upgraded the motors for piece of mind, if a motor goes while you are in the air it will crash spectacularly. I'm putting together a 550 at the moment so I can avoid that particular problem. The white anti grav's are the same as mine and should give you more flight time with a heavy phantom but at the altitude you live at i'm not sure whether you will get the benefits I get at sea level. Would be interesting to find out your testing after installing the anti gravity motors. I use an infra red thermometer after every flight to check motor temps for irregularity so I can predict a possible motor failure. Any thing to prevent it from plummeting to the ground or water.

 

[jumanoc]

Sounds like you have the maintenance pretty sorted on the stock motors. I personally upgraded the motors for piece of mind, if a motor goes while you are in the air it will crash spectacularly. I'm putting together a 550 at the moment so I can avoid that particular problem. The white anti grav's are the same as mine and should give you more flight time with a heavy phantom but at the altitude you live at i'm not sure whether you will get the benefits I get at sea level. Would be interesting to find out your testing after installing the anti gravity motors. I use an infra red thermometer after every flight to check motor temps for irregularity so I can predict a possible motor failure. Any thing to prevent it from plummeting to the ground or water.

Not related to T-motors.... let's talk about a scenario with stocks motors only.

1) When is the "right time" for change the motors ? (after N flights ?, after a bump/ crash ?, when sounding strange ?)
2) Should I change all at once or one by one ?
3) A failure can occurs any time, even with just replaced new motors... so how do you know ?

My answers are: After landing, ALWAYS check each motor (hear it, turn manually... feel it, touch it for hot temp...) even if new motors in your bird.

 

[boat chaser]

Sounds like you have the maintenance pretty sorted on the stock motors. I personally upgraded the motors for piece of mind, if a motor goes while you are in the air it will crash spectacularly. I'm putting together a 550 at the moment so I can avoid that particular problem. The white anti grav's are the same as mine and should give you more flight time with a heavy phantom but at the altitude you live at i'm not sure whether you will get the benefits I get at sea level. Would be interesting to find out your testing after installing the anti gravity motors. I use an infra red thermometer after every flight to check motor temps for irregularity so I can predict a possible motor failure. Any thing to prevent it from plummeting to the ground or water.

Not related to T-motors.... let's talk about a scenario with stocks motors only.

1) When is the "right time" for change the motors ? (after N flights ?, after a bump/ crash ?, when sounding strange ?)
2) Should I change all at once or one by one ?
3) A failure can occurs any time, even with just replaced new motors... so how do you know ?

My answers are: After landing, ALWAYS check each motor (hear it, turn manually... feel it, touch it for hot temp...) even if new motors in your bird.

Let me know how you go with your new motors.

1) When damaged or when your 'upgrading'
2) if upgrading, all, they are different dimensions. If stock, replace problem motor with new.
3) you never know when your bird may drop out of the sky, to many reasons, electrical short, prop coming off , motor failure, battery problems. All you can do is try and prevent these things from occurring. Check connections, check prop nuts, monitor motors for balance, temp and abnormal noise, get a better battery charger so you can better monitor battery condition.

 

[miskatonic]

With 920 kv motors I get an extra 1:30s with the gws 9050 tri blades compared with any of the twin blades. What motors did you use for your testing jumanoc? Also the tri blades seem to work better if your phantom is over 1150g. My testing weight was 1246g.

I put GWS 9.5 tri-blades on today and was happy with the results. As far as I could tell the tri-blades were more efficient with a heavy load near the end of the flight. With two blade props what normally happens is the Phantom looses efficiency near the end of the flight. This can result in some sluggishness; eventually the Phantom will lose altitude. What I got was a smooth flight from take off to landing. There was no sluggishness and I had control all the way through the second voltage warning.

I have one serious concern with the quality of these blades. They are flimsy and I am not sure how long it will take before one breaks under the stress of flying. I wonder how difficult it would be to carbon re-enforce these blades so that the life of the blade is longer and they are better for filming. I also wonder why there are no carbon fiber tri-blades on the market currently.

 

[martcerv]

I have flown these props quite a bit and have pushed them to 120kmh with a 1.2kg phantom have done loops and all sorts of high g turns. Never had an issue in flight and when balanced properky can give jello free video with very smooth flight.

Having tried different triblades this profile works best, in a carbon prop they would be stiffer but thi carbon would likely break before these. Any impact with the ground tends to break these though and so I have gone through a few props. I did hit a tree very hard yesterday and bounced off it and continued flying. Only to hit the same tree harder next flight flipping over and breaking a blade lol.

I was pushing my luck squeezing through tiny gaps made it about 30 times through this one gap and failed twice.

 

[boat chaser]

crashes into feature walls in holiday apartments will break the tri blades, I have tried this.

 

[martcerv]

Was it a feature wall before it had a phantom embeded in it? I dont mind that they break on impact as this takes some load off the motors.

On my last few flights after hitting a tree pretty hard and flying out of it, I then made one more flight whuch I ended with hitting the same tree harder. I broke one prop on that crash and noticed asecond prop was cut about 70% through a blade. This may have been from the earlier crash or the final one I am not sure. I didnt notice this after inspecting the props for the last flight but almost missed it again when checking props at home and rebalancing the ones that were undamaged. If this happened the earlier incident and I flew with this prop it says a bit for its strength that it didnt break off with it hanging on by very little.

 

[Peter Patricelli]

OK, I am going to try an opposite tactic. I have bought two different sets of the GWS 9050 3 blades. With the first set in a timed standard hover carrying heavy load(364 gms) I only got about 4 minutes flight to first warning...a bit better than stock props but disappointing. Using 9 x 4.7 CF 2 blades I did much better. Unfortunately broke one of the 2 blade set, awaiting replacements, and suddenly I have a working Tarot gimbal. So suddenly I have lots of reasons to fly with a medium load. (Tarot = 180 gms, Hero 3 = 75 gms) After reading repeated glowing reports on the gws 9090-3's I ordered another set directly from GWS. Different color. Hmmmm....maybe. With that medium load, the 3 blades hit first warning at 4 minutes with a freshly charged battery.

Is anyone else NOT finding the 3 blades to be better (in terms of longer flight) with loads? I want to compare notes and see I I/we can determine what is souring our systems. I notice Jumanoc's speed to better but flight time to be worse. For me, I want flight time.

 

[martcerv]

Peter can you give your total fly weight as giving a load weight is hard to really compare to anything and I have no idea what your load weights add up to. I assume 800g + your weight but its much easier for anyone to get an idea if you simply give total weight as you fly including battery. My guess on your medium load is 800+180+75 for 1065g so this is quite a bit lighter then my light load of 1200g formally 1150g but just got a little fatter.

I have added 40g with the OSD and PMU upgrade and when flying with a filter which is most flights total is now 1215g for 2700 batt and 1201g with the 2200's. I havent flown my 3d setup for a while but that was just over 1300g.

I dont currently have a full set of 9x5 carbons as I broke a prop and never re ordered after getting better times and performance out of the gws 9050.

What different colour did you get I have only ever seen them in black are these the exact same props you are using?

http://www.multiwiicopter.com/products/sku-27

Do you have a link to the 9x5 carbons your using as I will give them a try on my setup, the ones I had were ok but I was getting better performance and time out of the GWS. Though I have to say I never simply hover around generally cover a few kilometers each flight.

With the OSD installed I can get a better indicator of whats going on with the battery and I always try to come back with at least 11v unloaded in the battery. Its quite interesting to see voltage drop under load and as the data is coming direct from the NAZA and I get very much the same figures when testing the battery voltage after the flights its safe to say the OSD data is very accurate.

 

[boat chaser]

It seems that upgrading the motors in conjunction with the use of these props and a heavier phantom will give you the best results. I understand the t-motor are a more efficient motor although they are also slightly heavier. It seems with the stock motors that you will get a speed and lift increase but no real filight time benefit. So i'm led to believe that the efficiency of the motor is the reason for the increased flight time over the stock motors. This is a pure assumption and I would appreciate others feedback.

Recently went to home made dual batt fpv and getting 14.5 mins - 15.5 till 2nd voltage. Haven't tested the twins with this setup (1388g).

 

[martcerv]

It is quite likely the t motors give the extra efficiancy but I am finding much less flight time with all other props against these especially when heavy. Its also the reason I first tried them because I found going heavy with other props I had way less lift and also shorter battery life. I havent flown them without a camera and fpv ever so lightest I have flown is 1150g with these.

I really want to know what peters actual weights are as when the phantom is lighter and not lift limited then its quite likely these props will not give any more flight time and could actually hurt this. But first battery level warning at 4 min is very odd as I have never been like that only if flying full speed manual acrobatic at 1300g would I get to first level in about 4 1/2 to 5 minutes. Flying light shouldn't give less battery time then flying heavy no matter how I look at it and with 2200 batteries at 1300g I still get well over his time to first battery warning flying hard not just hovering so its a bit odd.

I dont think there is any real doubt that a dual blade is more efficient then a triblade if they both give the same lift. So a 9x5x3 vs 10x4x2 should be similar lift but the dual setup would use less power. Comparing a 9x45 dual and 9x5x3 there will likely be a point where weight will favour one over the other as the dual blade runs out of lift and starts to chew battery. At lower weights this will likely be reversed and the reduced efficiency of the triblade would hurt its total flight time.

 

[martcerv]

I did my slowest flying with no wind trying out these props, using a 2700mah storm 30c battery and 1214g phantom mostly very slow flying around some kangaroos I got 11 min 10 seconds to 10.4v under load which was 11v with no load after landing. The best part of it was that the only footage I got on the SD card was me going "oh fu$%" when I turned it on after the flight thinking I was turning the camera off. :x I did get some pretty cool shots of the kangaroos but at least I know where they live now and will go back next week armed with a gimbal too.

This isnt my first time making this mistake since getting the OSD, I used to have the GoPro OSD on which would tell me if it was recording or not, now I turned that off and so if I forget to press record I dont know.

I do have a timer on the futaba radio and go by the voltage levels on the radio trying to bring it back with 11v accounting for the load voltage drop in flight.

 

[Driffill]

I decided to make the most of the good weather today and fly with the tri blades. I've had the phantom sitting with them on for a few days, and a friend came over late this afternoon and I mentioned I was thinking of flying it, he wanted to see it. As I got everything ready and walked out the front, I seen a few more mates walking past my court and they came down to watch as well.

I was caught out by the bystander to crashing ratio. The more people watching, the more likely you will crash, I had 4 friends standing with me. Plugged in the battery, had the gopro set up ready to go. I took a few steps back, and was explaining the led flashes to everyone and showing the OSD on the LCD. Pointed out I was waiting for the 20 green flashes to signal ready to go. Finally got the signal, I let it sit for a little bit more then fired up!

This it where it got interesting, on lifting off I had to correct a little as it tilted the the right a little, once I was off the ground when I went to let to into a hover, the phantom darted off to its right hand side, stupidly I tried to correct it but yaw-ed instead. Once I realised I was losing (ok, I had lost control!) I bough the throttle down to (crash) land it, but the time it came down it was over my neighbours fence (they know I'm a gizmo person, by the time I got to there door, there were calling me over the fence to ask if this thing that fell for the sky was mine).

Got it back, three props were broken (concrete landing) so I pointed out to my friends that a new set of blades and it'll be good to fly lol. The body had no damage, all legs and CF plates were still attached, even the gopro was still sitting nicely. So I said my goodbyes to my friends and came in to asses the damage and hopefully swap to stock props are try again (test if it was an internal issue or a bad prop fitting). As I went to remove the hub of a damaged prop, I felt the motor housing pull up with little force. I had lost the E clip off the bottom of the motor.

Ok, so not a major issue, crack open the shell, notice the video cables have come off the OSD, but that's an easy fix. Dig out the E clip and washer from in the body, remove the motor and go to fit the E clip (I've done it before, had the clean dirt out of the motors) as I'm squeezing the E clip on, I feel it give, but not the way it should. The E clip had broken into 3 pieces!

Anybody know where I can get some of these E clips? I've been asked to bring my heli to an event on the 27th of this month so I thought I had better test the tri blades as I didn't want to fly them first time over car and or people. I think I'll stick to the stock props for this event lol!

 

[martcerv]

Did you muck up the rotation by any chance on one of the props? probably hard to tell after breaking most of them. I did do it once and on takeoff it went one way and it tried to correct but realized I was losing and killed the motors. I had 3 CCW and 1 CW prop on which isn't a good mix, only broke the one there and had I launched faster it would have took off hard to one side possibly like yours.

Not sure where you can get the clips maybe try a hobby shop or Jaycar would be the first place to try.