Notices
Ask the Expert Sal - Electric Airplane Advice Here is your chance to ASK SAL, the expert for all your electric flight related questions. If you are not Sal, please do not answer questions in this forum.

Power setup sanity check

Old 05-15-2007, 07:59 PM
  #1  
Junior Member
Thread Starter
 
Join Date: Mar 2006
Location: Andrews AFB, MD
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
Default Power setup sanity check

Sal,

I try to keep this brief, but I was hoping you'd ring in on a sanity check for my electric power setup I have planned.
My project is a ducted fantrainer 600 designed by Paul Willenborg and was featured in MAN back in Jan 1990.
See my photo of scratch build to date.
The target weight I have is about 26 ounces without battery.
I have a brushless outrunner E-Flite 400 Ducted fan motor 3500KV
E-Flite 40 AMP brushless ESC
Prop will be a cut down Cox pusher 5" X 3-1/2" cut down to 4-5/16"
Wing Area is 195 SQIN
Wing Span is 36-1/2'
Length is 34-3/4"
I'm plannning on a Li-Po battery probably 3S rated somewhere just around or slighlty above 2000 Mah

Is any of this "marginal", I'm not looking to burn holes in the sky, but am hoping this setup will give me at least 7-10 minutes flying with a little throttle/power management.

Apprecaite your time and expertise here.

Steve
Attached Thumbnails Click image for larger version

Name:	Rp44271.jpg
Views:	19
Size:	48.9 KB
ID:	685296  
Old 05-15-2007, 09:56 PM
  #2  
Senior Member
 
Join Date: Aug 2002
Location: Williston, VT,
Posts: 218
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Power setup sanity check

are you using the system as a pusher or a ducted fan? Why not use the suggested ducted fan use dby the designer?
Old 05-16-2007, 07:07 PM
  #3  
Junior Member
Thread Starter
 
Join Date: Mar 2006
Location: Andrews AFB, MD
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Power setup sanity check

To answer your question it's a pusher configured inside a duct.
The original design by Paul Willenborg used a Cox .049 in a pusher config, within the duct/shroud
as a cheap way to learn jet/fan flight. The full scale bird was just that a way to train jet jockeys without the cost of jet.
I'm using the E-Flite 400 as a pusher in the same config, mounted at aft end of fuse with a pusher prop. I thought about doing a mod and putting the motor behind the prop but I didn't like the idea and how the change may affect flight characteristics. Anyway I understand and have read up on as much electric info as I can..just wanted someone with some expertise to give me a ballpark on whether this project will fly. I attached a 3 view of the full scale bird so you can see the duct with the pusher config. Thanks again for your time and expertise.

R/
Steve
Attached Thumbnails Click image for larger version

Name:	Ol31256.gif
Views:	28
Size:	20.6 KB
ID:	685816  
Attached Images   
Old 05-24-2007, 11:42 AM
  #4  
Senior Member
 
Join Date: Aug 2002
Location: Williston, VT,
Posts: 218
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Power setup sanity check

The outrunner will be operating around 35,000 RPM. That seems too high for the motor to handle. Most Outrinners cannot go above 20,000 RPM

Based on an inrunner motror with similar Kv you would get in the vicinity of 28 ounces of thrust. I would think around 27-30 amps with 110 mph prop speed. Does that sound good to you for this airplane?

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On


Thread Tools
Search this Thread

Contact Us - Manage Preferences Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.