Author Topic: New 13 x 5.5 EP - DROP THE "W" (Read 1975 times)

Dennis Adamisin · « **on:** July 19, 2011, 04:39:39 PM »

I receved the dozen prototypes of the new 13x5.5WEP (Wide [/s] Electric Pusher) and have sent 10 of them out to evaluators. I asked them:

* Get RPM seting for the new prop versus the thin 13x4.5P and/or the thick blade 13x4.5P
* Get a comparison on battery usage
* To get back QUICKLY so we can share results with the forum and order the inital samples.

Until the results are in I will not be soliciting orders, but upon successful test results I am going to ask (beg, grovel) all who are interested to buy some!

Stay tuned...

Keith Renecle · « **Reply #1 on:** July 19, 2011, 11:26:06 PM »

Hi Dennis,

That is going to be interesting. Did APC manage to send you any of the modified 12 x 6 props yet? Just curious.

Keith R

Crist Rigotti · « **Reply #2 on:** July 20, 2011, 07:29:00 PM »

I received my samples today. After inserting the correct ring into the back of the hub and balancing here are my initial findings.

The WEP prop came pretty close to being balanced. Didn't take much sanding on the "inches" side to balance it. BTW, I just checked all of my 13x4.5EP props that have been balanced and all have the same "inches" side sanded.

I am comparing all 3 versions of the 13x4.5EP props. The thin hubbed version, the thick hubbed version, and the WEP 5.5 version.
After balancing the WEP, I weighed them:
Thin hub = 25g
Thick hub = 31g
WEP = 33g

Then I measured the hub thickness:
Thin hub = .352"
Thick hub = .394"
WEP = .413"

Then I measured the blade width at the widest part (2.5" from the center of the hub):
Thin hub = 1.119"
Thick hub = 1.119"
WEP = 1.119"

That is not a typo. The WEP blade width is exactly the same as the others. Here I thought that the WEP was supposed to be a wide blade? Doesn't look like it is. I've included 2 pictures of the blade width.

The 3rd picture shows the thickness of the hubs and the blades. The thin hub prop in on the bottom, the thick hub prop is in the middle, and the 5.5 WEP prop is on top.

It's too windy to fly tonight but tomorrow I should be able to get some preliminary flights in and data log them for some hard facts.

Andrew Borgogna · « **Reply #3 on:** July 22, 2011, 09:57:35 AM »

Guys
What is the application you are aiming at for this prop, and what prop does it replace?
Andy

Darkstar1 · « **Reply #4 on:** July 22, 2011, 10:04:50 AM »

Wish I had some of those props now. I have a whole week of 5-10 MPH wind and damn near 100deg temps

were cookin here.

Dennis Toth · « **Reply #5 on:** July 22, 2011, 12:08:55 PM »

Crist,
Looks like the difference in between the WEP and the normal is that the WEP has a slight curve to the trailing edge as it progresses to the tip adding a little blade area a little further out. Would be interesting to do a tracing of the WEP then add the normal EP to see were the difference is. Do all hubs have the same undercamber in them? Will be interesting to see the difference in Amp load.

Best, DennisT

Crist Rigotti · « **Reply #6 on:** July 23, 2011, 11:03:40 AM »

The baldes are the same.

Dennis Adamisin · « **Reply #7 on:** July 24, 2011, 08:04:01 PM »

More dimensional info. Big thanks to my brother Dave who has a reverse pitch gauge he was able to measure the pitch. While he was at it he measured the blade width and thickness. Crists's post had made some comparisons, here's some data. The comparisons are between the "old" thin blade version of the 13x4.5EP and the "new" 13x5.5WEP.

* In keeping with APC's new design philosophy, the new prop has a substantially different airfoil than before. The undercamber is all but gone and the prop is thicker under the leading edge, raising the leading chord line quite a bit. Since the pitch gauge treats all props as flat backed, that means that the pitch measured on the new prop is actually a little bit higher than shown here. Thus the pitch comparison is shaded by that. The new prop has a undercambered "cuff" in the inner blade stations, that serves to shade the pitch measurements somewhat lower there. Confusing isn't it? Still it is pretty easy to see the new prop is clearly higher pitched. (See table & attached graph)

* One surprise is that the "wide" blade is only .040" wider on average than the older prop - not much to talk about there. (See table & attached graph)

* The new blade is thicker and substantially stiffer than the old. This is why it also weighs some 9 grams more. However blade flex was the only negative that anyone ever shared about the thin blade 13x4.5 - they probably will not have that complaint against the new prop. (See table & attached graph)

Of course the proof is in the flying. there are six evaluators out there, so far two have reported back with positive reviews of the new prop - but I want to hold of saying too much until the others check in too.

My apologies for the sloppy plain text table!

   13.4.5EP 13x5.5WEP 13.4.5EP 13x5.5WEP 13.4.5EP 13x5.5WEP
Station Radius Pitch Pitch Width Width Thickness Thickness
   2 1.272 5 6.8 0.891 0.913 0.119 0.223
   3   1.666 5.5 5.75 1.005 1.043 0.107 0.204
   4   2.06 5.4 5.8 1.085 1.129 0.113 0.177
   5   2.454 5.4 6.25 1.117 1.165 0.116 0.156
   6   2.848 5.4 6.25 1.11 1.16 0.112 0.145
   7   3.242 5.4 6.25 1.069 1.127 0.108 0.137
   8   3.636 5.5 6.25 1.006 1.068 0.108 0.124
   9   4.03 5.6 6 0.924 0.97 0.093 0.116
   10   4.424 5.9 6 0.834 0.875 0.087 0.104
   11   4.818 6.2 6.2 0.727 0.757 0.077 0.092
   12   5.212 0.634 0.66 0.067 0.078
   13   5.606 0.535 0.554 0.058 0.064

Crist Rigotti · « **Reply #8 on:** July 24, 2011, 08:13:16 PM »

Dennis,
Put in a bunch of flights today. I'm compiling the data. Then I'll send it off to you.

Dennis Adamisin · « **Reply #9 on:** July 27, 2011, 04:37:57 PM »

When I gave APC the parameters for the new prop the resulting design is a normal APC planform. It really is not a Wide. I discussed this with APC and they agreed; the new prop will drop the W and will just be a 13x5.5EP. The props will be listed and labeled without the "W" however we can expect that first samples will still have the W molded in. This will change with subsequent production batches.

Crist Rigotti · « **Reply #10 on:** July 27, 2011, 05:35:19 PM »

Dennis,
Should we sand off the "W" on our test props just to avoid confusion?

Dave Adamisin · « **Reply #11 on:** July 27, 2011, 10:27:09 PM »

Quote from: Crist Rigotti on July 27, 2011, 05:35:19 PM

Dennis,
Should we sand off the "W" on our test props just to avoid confusion?

Probably not, it's kinda like that matress tag......

WhittleN · « **Reply #12 on:** July 28, 2011, 07:38:28 AM »

Crist
Live on the wild side - sand it off. The prop police won't get you. What could the max sentence be?
BTW Crist received the props you sent me - thank you very much. I owe you.
Regards
Norm

Dean Pappas · « **Reply #13 on:** July 28, 2011, 08:01:37 AM »

I'll bet you pulled the tags off of pillows, too!

Dean P.

WhittleN · « **Reply #14 on:** July 28, 2011, 08:23:22 AM »

Dean
I have wild man streak in me too (between Heart Attacks). All them tags are gone. Even the ones in the Hospital.
Norm

Mark Scarborough · « **Reply #15 on:** July 28, 2011, 08:26:18 AM »

take the tags off the mattress, put them on the pillows, take the tags off the pillows and put them on the couch cushions,, then I take the couch cushion tags and put them on the mattress, lets see them figure THAT mess out muah ha ha,,
oh isn't this about props or something?

WhittleN · « **Reply #16 on:** July 28, 2011, 08:40:06 AM »

Oh, we have already established that Dennis isn't getting any of the props he sent us back. With or without the "W". They are staying on our airplanes. Dennis will publish the info we sent him. I'm sure it will come out very positive.

Norm

Crist Rigotti · « **Reply #17 on:** July 28, 2011, 09:17:39 AM »

Quote from: WhittleN on July 28, 2011, 08:40:06 AM

Oh, we have already established that Dennis isn't getting any of the props he sent us back. With or without the "W". They are staying on our airplanes. Dennis will publish the info we sent him. I'm sure it will come out very positive.

Norm

You got that right! They are staying put!

Dean Pappas · « **Reply #18 on:** July 28, 2011, 11:51:06 AM »

As far as I can tell, there are two reasons Bob is goinf to remove the new prop:
1) we agree that he needs to do some A/B testing at slower lap times, and
2) after that's done he wants to see if more stiffness is better by adding some carbon.

Dean P.

Dean Pappas · « **Reply #19 on:** July 28, 2011, 11:52:22 AM »

Quote from: Mark Scarborough on July 28, 2011, 08:26:18 AM

take the tags off the mattress, put them on the pillows, take the tags off the pillows and put them on the couch cushions,, then I take the couch cushion tags and put them on the mattress, lets see them figure THAT mess out muah ha ha,,
oh isn't this about props or something?

Kaptain Kaos strikes again!

Dennis Adamisin · « **Reply #20 on:** July 28, 2011, 03:51:01 PM »

I think SNL did a skit on the "Tag Police". Also watch out for the Killer Bees and especially...

LANDSHARK!!!

Mark Scarborough · « **Reply #21 on:** July 28, 2011, 06:59:54 PM »

Quote from: Dennis Adamisin on July 28, 2011, 03:51:01 PM

I think SNL did a skit on the "Tag Police". Also watch out for the Killer Bees and especially...

LANDSHARK!!!

Ok now your dating us,, I remember all to clearly those sketchs,, LOL,,

Dean Pappas · « **Reply #22 on:** July 29, 2011, 10:50:26 AM »

I thought that the SNL skit was an homage to the old Robert Klein routine.

Dean

Author Topic: New 13 x 5.5 EP - DROP THE "W" (Read 1975 times)

Dave Adamisin