Recently Turnigy has resleased a series of props that look very much like knock offs of apc props. Since the apc 12X6E thin electric prop has been a mainstay prop I thought I would compare the two. Unfortunately the pusher version is backordered but I was able to order a tractor version and compared it to the apc 12X6 E thin electric in the tractor version. The following is what I found.

Prop profiles are the same. You can lay them right over one another and looking at the blade face they are identical. In cross section they are very close. I did not mic them because I do not have the tool. But they look very similar except the Turnigy prop arc aft towards the tip a bit when viewed from the leading edge.

The materials are clearly different. This was where I was concerned. I have other Turnigy props that have turned out to be profile knock offs of apc's and there were clear differences in materials. The first is that the Turnigy is somewhat clear. Its an amber color and you can see thru it when it gets thin enough, like about midway between leading and trailing edges whereas the apc is totally gray opaque. There is no hint of anything but resin in the Turnigy. No type of fibers are apparent though there may be. I have not fractured the prop yet to evaluate the material and will not do that until I have flown it. But after flying it and having my flying partner Rick Sawicki fly and evaluate it as well I will then flex it to destruction and see what the cross section of the material looks like. If you have ever broken an apc prop you know there is not a clean break like you used to see in for instance a top flite nylon prop break but rather a very ragged cross section with the impression of many fibers running span wise in the blade.  I cannot detect anything like that in this prop. You look thru it much like the old nylon props.

Pitch seems to be very close to the apc. The only variances I noted were because of the aft curve of the blade.

The hubs are different. The turnigy just has a small hole drilled in it as a pilot hole for what ever you want to open it up to. I have tried with other turnigy props of the same material to use a reamer to enlarge this hole but its too small for the reamer to work thru. You have to drill it with a drill press first. Not an always predictable task but doable. The tunigy hub in thinner however, than even the apc thin electric. As you know the apc electrics have been changed to include a thicker hub this year. The apc hub is 10.66 mm thick. The Turnigy hub is 9.5 mm thick.

The real story however is in the flex patterns of the two props. locking the prop in a vice at the hub and then applying equal weights to the blade tips towards what would be the rear of the airplane as mounted, the Turnigy prop shows very much more flex to the same load. Way more than 50% more. It is easily bent so the tip is perpendicular to the blades axis. The apc deflect back to an angle of about 20 to 25 degrees from blade axis with the same load. Also the flex pattern is quite different. The Turnigy begins easily discernable flex at about 1.5 inches from the center of the hub. The apc does not present clearly visable flexing till 3 inches out from the hub. I am not here to argue advantage of one flex pattern to another, I think that would require testing. But I am saying there is considerable difference. I have done some carbon fiber testing with electrics but only with glow props which I do not think are anywhere near an apples vs apples test. I think I'd have to see comparison of say a normal apc vs a carbon fiber prop of same design and size.

As to weights the apc weighed in at 23 grams. I used a new prop out of the package without a shim for the prop hub. The Turnigy weighs 21 grams and that is with the hub only drilled to about 1.5 mm diameter.

So clearly from a static perspective there are clear differences. I will do flight tests and report on these when Rick and I can get together so we have multiple inputs from the handle on multiple planes and observer observations in flight performance from outside the circle and tests on multiple airframes. He and I routinely fly a total of about 6 or 7 planes on the 12x6 size props so we can view it over quite a range of airframes.

 Hope this gives some basis for others to decide on testing or not and as a baseline. If you are going to test the Turnigy please see if you get similar flex patterns to what I reported here. The flex was not suprising to me as I have used smaller turnigy electric props in rc and seen the flex patterns before. Interestingly I have not found the flexibility of these props to increase their resistance to crash damage.

bob branch

Wynn

I don't think weight has all that much to do with it. The prop shape and the thrust it produces and the amount am amps it consumes to me are the keys in electric. The year the governor systems did not work I tested a lot of props to try to find something that worked. Nothing I could find in wood compared to the apc thin electrics as far as amp draw. I could get more thrust for a given amps with the apc thin electrics than anything else and really, nothing else even came close. That was a number of years back now. I still have a good stash of thin electrics both in tractor and pusher configurations. One of the things I look for is performance per amount of amps required for the pattern. That is why I gravitated to the axi 2826/12 power system and why I like the apc thin E so much. I don't come wanting for anything in flight performance with them either. But I am planning on testing different props this year since the new apc wide pusher does require additional rpm and amps. Its still acceptable but I don't like going in that direction when its worked so well for me to go in the other. Like anything else in stunt your mileage may differ. I'd really like to see people post current draw data on different props in their planes. I think we are still shooting in the dark on electric props. We need more hard data. I'm looking forward to trying the JXF props. Thanks,

bob branch

Wynn

Where did you get the corbon copy of the thin 12X6 and is it a pusher or tractor? I would really like to see a comparison of the turnigy, the apc, and the carbon flown together on the same plane with the same flier and rpm, amp draw, lap times and performance impression. That would give us a really good basis to work from. Noodle to very stiff. I don't think we can just accept the results we see from glow props because we do not have the power pulses that glow does. I think the thinness of the blades has a lot to do with the apc's efficiency. But as we have seen from different iterations of props apc has made for us there are still lots of variables in the airfoil of the props.

bob

Wynn

Where did you get the corbon copy of the thin 12X6 and is it a pusher or tractor? I would really like to see a comparison of the turnigy, the apc, and the carbon flown together on the same plane with the same flier and rpm, amp draw, lap times and performance impression. That would give us a really good basis to work from. Noodle to very stiff. I don't think we can just accept the results we see from glow props because we do not have the power pulses that glow does. I think the thinness of the blades has a lot to do with the apc's efficiency. But as we have seen from different iterations of props apc has made for us there are still lots of variables in the airfoil of the props.

bob

Bob ,   Bob Whitney made the APC 12 x 6 pushers - they are OK as far as moulding goes - a little rough - but very usable - they balanced up nicely and seem to be a nice prop.    I am starting the process of making my own ones - trying to get a nice smooth finish to them.