Guys,

I purchased an Air Master Screw 11-7 3blade Pusher for testing on my 600 sq Excitation with an AXI 2826-10 motor. First, I checked the pitch and found it was under pitched and measured about 5.5 on one blade and 5.25 on the other two at the 75% station (this is were I check all my props and use it as a reference point). The prop is glass reinforced nylon so it heat pitches easily. I set all blades to 5.5 and balanced the prop. I needed to adjust the three blade spinner blade cutouts for the pusher so I did a quick prop test without the spinner. Rpm is set to 9000 and it pulled 36.9 amps. Once I finished the spinner I wanted to make sure it was running smooth so I did another test run. For grins I checked the amps and found it was 34.1 amps. It appears that a full spinner reduces the prop drag around the hub and the amp draw (the root of the blade doesn't add much to the pulling power of the prop) by 10%.

Best,            DennisT

I find it amazing to think that with electric stunt we can actually hear these differences. You can even hear the difference in a hard or soft corner, whereas with the wet setup the engine noise masks these things. Talking about spinners, another neat thing about electric, is the lack of motor vibration, so even a small out-of-balance problem on a spinner shows up easily. I find this especially noticeable if you have a slower run-up, or if you are setting the rpm manually. It's most interesting that the spnner makes a difference in noise and also current.

Keith R

Hi Dennis,
What was the change in battery consumption, if any?
Thanks,
Dean P.

Dennis,

Does the 3-blade prop make as much noise in corners as the 2-blade?  Does it make more noise in corners than flying level or doing round loops?

Dennis
 I flew today with the Master Airscrew  11x7 P and it works great, same result you have.
 My next Question is what kind of spinner did you use for the pusher 3 Blade prop?
  I also tryed the APC 13X4.5 EP and just could not get to work the way the 12X6 EP that I was using , But the 11X7 P  3 blade is Great and better than the 12X6 EP.      By the way the 3 blade prop is vary quiet, sounds like a fan.

Hi Larry,

Did you repitch the MAS 3 blade like Dennis did, or did you run it stock right out of the box?

BTW: TruTurn makes an excellent electric spinner. They can make them in 3 blade and will cut/modify them for any prop.

Rudy I ran the prop right out of the box , did not check the pitch, but will when I get a chance just to see what it's like. Will check on the spinner from Tru Turn. Thanks

Thanks Larry, that's good news. I'm lazy so I like "right out of the box". 

If it is any where near the APC 12 x 6 in performance and it is quieter and 1/2" more grd clearance, it sounds like a winner.

TruTurn spinners are beautiful. Not cheap, but worth every penny. 

Go to their web site for more E spinner info. :

http://www.truturn.com/cgi-bin/store/agora.cgi?p_id=tte122002b:13&ppinc=spinners130&exact_match=on

Click on the "special slotting" section on the right side of the page     

ALMOST LIKE CHROME

If you want yours to look almost like chrome here are a few hints to add to the their web site instructions:

2. If you want to make a spinner, or a landing gear, real shinny then here is the best way to do it:

        http://www.tru-turn.com/faq-29.htm

It is not the polishing that does it, it is the SANDING that gets the job done. Look at your spinner or LG with a magnifying glass and you will see how rough it really is. This has to be taken care of waaaay before polishing takes place. Polish alone will NEVER take down the rough mountains in the finish, it needs sandpaper. I have done three of my 5" spinners and 3 pair of LG and they all have come out looking almost like chrome.

If you do this, try these:  1. buy lot's of latex gloves and use them on both hands all the time during the process. If you don't do this you will wish you had! Please don't ask me how I know this.     2. work over a kitchen size garbage container WITH a liner in it, have a little water in a plastic container for the wet sanding part.  3. have a large roll of paper towels at your side. 4. wear OLD clothes, it's messy! and ..... BE PATIENT!

It is not hard to do, just messy and time consuming. I would NEVER do it if I could pay for it to be done. I would have gladly added another $50 to the cost of my $180 spinner to have it come already looking like chrome!!!! The LG is a little easier, and well worth the effort but still I would pay to have it done, it is not a "fun" job. But the results are very rewarding, and with a little auto wax applied after your done, the shine will last for years. 

Please let us know how you make out with your spinner. I have my MA 11x7 3B on order.

Regards, 

 

Dennis:
I used 65 ft lines eye to eye, lap time is 5.2 at 9K rpm plane is a ARF P-40 AXI 2826-10 TP 3900 4s Used about 2500 mAh  

Dennis :
 I just check the pitch on the 11x7P MAS and I got 7 pitch at tip and at station 8 on my Prather about 2" from tip it was 5 1/2 " pitch, will check balance next.

Larry,

First thing I do is clean off the mold flash lines on the edges of the blades. Next I check the blade lengths and true up as needed (I made a simple jig that Windy uses, it's a piece of 3/4" x 1 1/2" x 8" with a hold drilled and tapped for the 1/4" bolt. You then mark off blade lengths for the size prop you use. I then clamp a piece of scrap 1/2" sq  at the desired blade length and sand the tips so they just touch the block). Now you are ready to start balancing.

The way I have been doing it is place it on the balancer and see which blade falls toward the bottom, try it from both the left and right sides. I then sand on the face (I start with 320 grit) of that blade slowly, you will see it start to rotate up as the next heavy blade starts to drop lower. At that point I start to sand a little on the next heavy blade also. Three blades take a bit of work cause when you get the first blade to where it seems like it close you start the next heavy blade and find the first blade is still heavy. Once you get to this point you are close, take it slow and work back and forth between the two and at one point you will see one blade still hanging a little low. Once you bring it in you can then set the prop in any position and it will stay. You can then wet sand the blades with 600 and it will have a smooth finish. Odd thing is once it comes into balance minor sanding to clear up the surface doesn't seem to affect it.

Best,                     DennisT

Hi Gang,
I've always balanced 3-bladers by sanding or scraping on the heaviest blade until it balances perfectly with the lightest one. That means that both those blades will be UP at the same angle, and what used to be the middle-heavy blade now hangs vertically down. Then I shave the new heavy blade until it will sit still when released from the horizontal. I rarely have to repeat the process unless one blade was very light compared to the other two.

later,
Dean

Thank you guys for the Great info. on this prop. and balancing a 3B.   

Larry, did you really mean 6.2 sec/lap? Or is it 5.2 sec/lap? .... I fly my P-40 (same set up) at 5.0 sec/lap on 64 eye to eye lines using about 2,700 mAh/flight with very slow spool up and 9 extra laps at the end. Your Air Speed must be really sloooow? I don't see how you can keep it up in the overheads at that speed. Please tell us your secret. 

Regards, 

Woops! I must hit the 6 instead of the 5, yes it is 5.2 lap time..    

Bummer! .... I was hopeful that you found a new type of "Flux Capacitor" or "Beryllium Spheres" that would allow the slow, graceful flying that a 6.2 lap time would bring.   

Thanks for the bad news. 

I look forward to flying with you guys up there in the "civilized" part of CA in 2010. 

Warm Regards, 

Larry,

I did two things, first I sand down the area between the blades a bit (I used the medium size sanding drum). Second I sanded the posts inside the spinner so that they had about 1/64 wall left on the side that is near the hub. I was working with a 2" spinner, you need to work slow and sand the upper part of the posts almost flat, it does fit and runs true.

Best,         DennisT

Larry,

I balanced the prop first and then sanded the area between the blades on the hub after I got a clean fit. I checked the balance and mine was OK. Make sure the spinner engages the backplate smoothly. Once you have the correct clearance it will go it without forcing any of the side in. This is important because if you have to force the sides into the backplate slots it pushes the tip off center and the spinner will not run turn. Test it by simply spinning the prop with a good flip, if its off you will see the spinner wobble. The thing that caused mine to be off was clearance at the top of the hub line in the spinner, sanded somemore out of the posts (I found that I hadn't sanded deep enough down on one post, when down another 1/16" and all cleared, fit and no wobble.

Flew the three blade today in 15+ wind and turbulence off some trees. Compared to the IC guys I was going great. The ship seemed to penetrate going upwind really good. I wasn't waiting for the airplane to get through the up wind leg, it just flew around. Also didn't need to wait for the ship to regain speed before doing maneuvers. One thing I did notice was that it stayed out even when I positioned the maneuver off the wind (like were the wind rolled off the trees). It resisted the wind up very good. One thing I am still working on is selecting the CG location. On the first flight I had it where I had flown it with the big two blade and it turned pretty quick. On the second flight I moved the CG forward about 1/4" and it seemed better. I want to fly it there a few more times and then keep moving it forward until the turn gets soft then go back a bit.

Best,           DennisT

Dennis,
I didn't catch if you did post it, but do you have battery usage #'s (mAHr)  for 3 and 2 blade props---especially when your lap times are setup the same.

I just curious at what hit in consumption you take by going to 3 blades.

Guys,

OK, just finished charging two packs that were flown back to back. The three blade pack used 2545 mah (65%), the two blade pulled 2435 mah (62%)out of 3900 mah. I did some checking in my records and I did run a full 12x5.6 APCE P, it also had a lap time of 5.1 and pulled 2547 mah.

Best,                    DennisT