Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
December 12, 2018, 10:44:13 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: 1 ... 24 25 26 27 28 29 30 [31]   Go Down
Print
Author Topic: Let's talk E20  (Read 59378 times)
0 Members and 1 Guest are viewing this topic.
PaulBrad
Gold Member
*****

Kudos: 36
Offline Offline

United States United States

Posts: 324


WWW

Ignore
« Reply #750 on: September 22, 2018, 07:29:12 PM »

As George has noted, there are a variety of ways to stop your E20 prop. Ralph did look at alternative methods. The issue was prop run down time. The goal was to get the prop to stop quickly and reliably every time. The use of magnets in a bar rather than a strip of material that is attracted to a magnet provided a more positive prop brake. When the motor is shut off the prop stops almost immediately regardless of the slip stream strength.

Paul Bradley
Logged
Ralph B
Nickel Member
*

Kudos: 0
Offline Offline

United States United States

Posts: 1



Ignore
« Reply #751 on: September 22, 2018, 11:21:25 PM »

As Paul pointed out I went with the magnetic brake for it's ability to stop the prop quickly during my experiments with his 3D printed folding prop. The folder operated reliably with the magnetic brake and I used it at the 2017 US Nationals. Late last year I tried the 65 mm RJX or King Kong prop and retained the magnetic brake. I got a little better climb on the RJX and found the glide to be as good as the folder. That is what I used at the US National this year.

I use a home made prop adapter on my models. I start with a commercial brass threaded push rod end that is then drilled out to fit the 1MM motor shaft. The brass comes with a 1/32" through hole from the package. I machine an aluminum back plate for the prop that gets bonded to the brass with red Loctite. After cutting the adapter to it's final length I machine a small aluminum spinner to retain the prop and magnet bar. Adjusting the stopped position of the prop is very easy with this arrangement. The prop hub is drilled out to slip on to the prop adapter and the hub is also machined flat on the front and back sides. The prop adapter is bonded to the motor shaft with red Loctite. The attached photos probably make more sense than my description. The motor mount in the photos was cut from an old Horizon 4-Site gearbox. It has since been replaced with a 3D printed part but the function is exactly the same. The magnet in the motor mount is 1/8" X 1/16". The magnets on the prop bar are 1/16" X 1/16". I know what you are thinking and yes this does add a few tenths of a gram of weight but it's on the nose and can be offset with the battery placement. Two of my three E20 models needed some ballast to reach the 30 gram minimum weight so the extra weight of the prop adapter and magnets were not an issue. The model I flew at the last two Nats weighed 31.4 grams. I have not had an opportunity to fully trim out the lighter models yet.

Ralph Bradley
Attached files Thumbnail(s):
Re: Let's talk E20
Re: Let's talk E20
Re: Let's talk E20
Re: Let's talk E20
Re: Let's talk E20
Re: Let's talk E20
Logged
raggedflyer
Bronze Member
***

Kudos: 1
Offline Offline

United Kingdom United Kingdom

Posts: 65



Ignore
« Reply #752 on: September 23, 2018, 12:33:28 PM »

Thanks Ralph, I enjoyed the explanation.
Logged
Yak 52
Titanium Member
*******

Kudos: 58
Offline Offline

United Kingdom United Kingdom

Posts: 2,285


Free Flight Vagrant



Ignore
« Reply #753 on: September 23, 2018, 04:46:29 PM »

Interesting stuff about the magnet prop stopper, the pre-determined stop position sounds useful.
My electric circuit solution works as planned but I need to tune the timings a little...

Jon
Logged
FF Bruce
Gold Member
*****

Kudos: 13
Offline Offline

United States United States

Posts: 463



Ignore
« Reply #754 on: October 02, 2018, 11:14:46 PM »

Well the 2018 flying season in the Northwest ended last weekend. We had three contest E-20 was flown at each meet. Had a told of 9 different fliers and I ended up with the highest total time. Was able to get three maxes at each meet and won one fly off. At this last meet I was the only max out, many had 2 maxes but came up short on there third flight. As with most Free Flight it came down to picking the right time to fly. All the E-20's had good climbs,most are built up balsa and tissue but we have had a few all foam models. One was what I'll call a ultra high thrust with the motor about 1 1/2'' above the wing, it was very impressive. We all had fun and now look forward to next year.
Logged
wcstoddart
Bronze Member
***

Kudos: 1
Offline Offline

United States United States

Posts: 12



Ignore
« Reply #755 on: October 04, 2018, 10:06:18 AM »

FF Bruce

Congratulations on your E20 contest results.

Please provide contact information or further details on the "all foam" and "ultra high thrust" line E20 designs.

Chris
Logged
flytyer96
Bronze Member
***

Kudos: 3
Offline Offline

United States United States

Posts: 23



Ignore
« Reply #756 on: December 04, 2018, 11:08:44 AM »

Well, I'm starting to make some progress on Mini-E #2. Ya, I'm a slow builder. Thought I'd post some pics of the build.
Attached files Thumbnail(s):
Re: Let's talk E20
Re: Let's talk E20
Re: Let's talk E20
Re: Let's talk E20
Re: Let's talk E20
Logged
PaulBrad
Gold Member
*****

Kudos: 36
Offline Offline

United States United States

Posts: 324


WWW

Ignore
« Reply #757 on: December 04, 2018, 09:35:17 PM »

Your new Mini-E is looking good. I look forward to seeing the finished model.

Paul Bradley
Logged
flytyer96
Bronze Member
***

Kudos: 3
Offline Offline

United States United States

Posts: 23



Ignore
« Reply #758 on: December 06, 2018, 10:55:08 AM »

Thanks, Paul.

Attached is a pic of the horizontal stab. If I keep going at this rate, I should be able to "maiden" by the end of the year.

John
Attached files Thumbnail(s):
Re: Let's talk E20
Logged
FF Bruce
Gold Member
*****

Kudos: 13
Offline Offline

United States United States

Posts: 463



Ignore
« Reply #759 on: December 06, 2018, 09:23:28 PM »

You look like you know what you are doing. Nice job, I love flying mine must have a couple hundred flights on it.
Logged
flytyer96
Bronze Member
***

Kudos: 3
Offline Offline

United States United States

Posts: 23



Ignore
« Reply #760 on: December 06, 2018, 10:36:29 PM »

Thanks, Bruce. I know I sure enjoyed flying mine during the short time I had it. Hopefully I will still have this one for next years Nats.

John
Logged
Pappy
Bronze Member
***

Kudos: 6
Offline Offline

United States United States

Posts: 98



Ignore
« Reply #761 on: December 10, 2018, 04:12:16 PM »

Tachometer sensor test set up for a planned E-20 power train analyzer.
The goal is to evaluate motor and battery performance over 20 second
and 10 second intervals. It is apparent that not all E-20 motors and
batteries are created equal. Hopefully the analyzer will help pick out
the best motors and batteries on hand before each E-20 contest.
The “ticks” on the scope in the photo indicate the test motor was turning
about 14,500 RPM on a somewhat discharged battery. Initial RPM is typically
16,300 using a freshly charged battery with a stock motor and prop.

 -Pappy
Attached files Thumbnail(s):
Re: Let's talk E20
Logged
Pages: 1 ... 24 25 26 27 28 29 30 [31]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!