News:



  • May 01, 2024, 04:07:04 PM

Login with username, password and session length

« previous next »
Pages: [1]   Go Down

Author Topic: 12.75 x 4.5CFEP  (Read 2029 times)

Offline Jeff Traxler

  • T-Bone
  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 645
12.75 x 4.5CFEP
« on: July 08, 2017, 09:57:22 AM »
Here is another one of my prop experiments.12.75x4.5 CFEP with droop tips.Trying to cut down on vortex drag at the tip to save a few MAH.On the bench it is using about 3% less MAH in static tests than the same prop without the droop tips.The weather has been too crappy to fly it yet but Monday looks like the day
Logged
If you wanna sing the blues(Fly Stunt) you gotta pay your dues and "I know it don't come easy"

Offline Jeff Traxler

  • T-Bone
  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 645
Re: 12.75 x 4.5CFEP
« Reply #1 on: July 08, 2017, 09:59:24 AM »
I'm using 1K 3 oz. CF cloth on the front and back of the blades for stiffness.
Logged
If you wanna sing the blues(Fly Stunt) you gotta pay your dues and "I know it don't come easy"

Offline Jeff Traxler

  • T-Bone
  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 645
Re: 12.75 x 4.5CFEP
« Reply #2 on: July 08, 2017, 10:00:06 AM »
Front view
Logged
If you wanna sing the blues(Fly Stunt) you gotta pay your dues and "I know it don't come easy"

Offline Jeff Traxler

  • T-Bone
  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 645
Re: 12.75 x 4.5CFEP
« Reply #3 on: July 08, 2017, 10:00:48 AM »
one more......
Logged
If you wanna sing the blues(Fly Stunt) you gotta pay your dues and "I know it don't come easy"

Online Dennis Adamisin

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4342
Re: 12.75 x 4.5CFEP
« Reply #4 on: July 08, 2017, 10:43:24 PM »
Looks GREAT

I am flying the prototype Brodak SV-11 ARF Electric with an APC 13x4.5EP.  Great combo but that prop is much more flexible than yours.  I'm thinking your new 12.75x4.5CFEP is going to be a solid upgrade.  Bring one to Muncie for me!


Logged
Denny Adamisin
Fort Wayne, IN

As I've grown older, I've learned that pleasing everyone is impossible, but pissing everyone off is a piece of cake!

Offline Jeff Traxler

  • T-Bone
  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 645
Re: 12.75 x 4.5CFEP
« Reply #5 on: July 09, 2017, 06:38:49 AM »
Dennis,Already have one with your name on it.Do you need an 8MM hole?I am making those and 1/4".Trax
Logged
If you wanna sing the blues(Fly Stunt) you gotta pay your dues and "I know it don't come easy"

Online Dennis Adamisin

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4342
Re: 12.75 x 4.5CFEP
« Reply #6 on: July 10, 2017, 07:40:05 AM »
Quote from: Jeff Traxler on July 09, 2017, 06:38:49 AM
Dennis,Already have one with your name on it.Do you need an 8MM hole?I am making those and 1/4".Trax
Yes, the "normal" 5mm collet style adapter...
Logged
Denny Adamisin
Fort Wayne, IN

As I've grown older, I've learned that pleasing everyone is impossible, but pissing everyone off is a piece of cake!

Offline TDM

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 844
Re: 12.75 x 4.5CFEP
« Reply #7 on: July 10, 2017, 08:21:54 AM »
Shouldn't the tip sweep up instead of drooping? I am thinking winglets here but i might be wrong.
Logged
Each goal you meet is a moment of happiness
Happiness is the harmony between what you think and what you do. Mahatma Gandhi

Offline Jeff Traxler

  • T-Bone
  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 645
Re: 12.75 x 4.5CFEP
« Reply #8 on: July 10, 2017, 10:56:10 AM »
I borrowed the idea from the prop on one of the full size aircraft I built.The original Witcomb(????) winglet went above and below the airfoil.Don't know weather it's better or worse below but it is a good starting point.
Logged
If you wanna sing the blues(Fly Stunt) you gotta pay your dues and "I know it don't come easy"

Online Dennis Adamisin

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4342
Re: 12.75 x 4.5CFEP
« Reply #9 on: July 10, 2017, 02:03:09 PM »
Quote from: Traian Dorin Morosanu on July 10, 2017, 08:21:54 AM
Shouldn't the tip sweep up instead of drooping? I am thinking winglets here but i might be wrong.

Google Hartzell Q-Tip propellers.
Logged
Denny Adamisin
Fort Wayne, IN

As I've grown older, I've learned that pleasing everyone is impossible, but pissing everyone off is a piece of cake!

Offline Igor Burger

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 2166
Re: 12.75 x 4.5CFEP
« Reply #10 on: July 10, 2017, 04:28:27 PM »
This is Beringer's prop from 2006:

 
Logged

Offline TDM

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 844
Re: 12.75 x 4.5CFEP
« Reply #11 on: July 11, 2017, 08:14:25 AM »
One simple test is to run the prop stock then cut of and reshape tip without the tip geometry and compare to see if there is any difference in between the two.
If my goal was to reduce vortex I would go in this direction.
Logged
Each goal you meet is a moment of happiness
Happiness is the harmony between what you think and what you do. Mahatma Gandhi

Offline Jeff Traxler

  • T-Bone
  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 645
Re: 12.75 x 4.5CFEP
« Reply #12 on: July 12, 2017, 07:19:34 AM »
These tips have more of an objective than just reducing tip vortex.On full size aircraft they help with climb performance.They also help with spillage of thrust from centrifical force and lower prop noise(Not that that matters for E power).The wind and rain took a small break yesterday and I finally got to fly it.Very pleased with the few flights I got in and it performed better than I had hoped.Not used to having my airplane come out of the squares with such authority #^ #^ #^
Logged
If you wanna sing the blues(Fly Stunt) you gotta pay your dues and "I know it don't come easy"

Offline TDM

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 844
Re: 12.75 x 4.5CFEP
« Reply #13 on: July 12, 2017, 02:55:49 PM »
Just looking at your prop instinctively i think it will help with traction (climb performance).
An interesting experiment would be to compare 3 props identical in most ways. One prop same diameter as yours minus the curved tip, one prop more diameter, and the existing one.
What i am wondering is if perhaps more diameter would get the job done as the curved tip.
Since we run electric and can monitor battery usage we can ID for the same power consumption per flight what is more beneficial more diameter of less diameter with curved tips.
Also what is the difference between same diameter curved tips versus same diameter no tips.

Please in no way I am trying to talk you out of it or talk bad about it I am more interested towards data gathering and perhaps push this idea even farther.
How did you develop the tip shape?
Traian
Logged
Each goal you meet is a moment of happiness
Happiness is the harmony between what you think and what you do. Mahatma Gandhi

Offline Jeff Traxler

  • T-Bone
  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 645
Re: 12.75 x 4.5CFEP
« Reply #14 on: July 12, 2017, 07:29:12 PM »
Traian,Did you see the photo in my earlier post of the prop tip from my homebuilt?I used to work for a guy that makes a lot of props for homebuilt experimental aircraft as well as a couple NASA wind tunnel fans and got the idea from that experience.This prop is the first I have tried with these tips and wasn't really sure if I could get them out of the mold or how stiff the tips would be.So far so good on those two.The tips are VERY rigid and didn't look to be changing shape during static tests.I plan on flying a lot in Muncie next week and have a few for others to try and see how they like them.Hope to put one on the new ARF SV-11 Dennis Adamisin has and get his 2 cents worth as well.I'll post more info after I return home.
Logged
If you wanna sing the blues(Fly Stunt) you gotta pay your dues and "I know it don't come easy"

Advertise Here
Pages: [1]   Go Up
« previous next »
Tags:
 


Advertise Here