SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
This thread is privately moderated by peterangus, who may elect to delete unwanted replies.
Old Jul 31, 2009, 10:39 AM
Registered User
peterangus's Avatar
Blackpool, Great Britain (UK)
Joined Dec 2003
1,342 Posts
Discussion
Power-to-weight ratio for the complete power train

BLOG 002
I have done a study, with interesting results, which are shown in graph 1. The motor data is taken from graph 2. The computation is shown in the table.

By "complete power train" I mean motor+prop+ESC+wiring+battery.

Please note the % no-load speed at which the best power-to-weight ratio occurs. 70%NLS for a 5 minute WOT motor run. 74%NLS for a 10 minute run. 78%NLS for a 20 minute run. 80%NLS fof a 40 minute run.

Note that peak efficiency is not a good operating point unless you are into long motor runs.

Graph 3 shows an example of how the data translates into powertrain weight for a particular application.
Name: bor.jpg
Views: 361
Size: 77.8 KB
Description: GRAPH 2

Name: ptwt.jpg
Views: 352
Size: 97.4 KB
Description:

Name: ptw2.jpg
Views: 380
Size: 79.8 KB
Description: GRAPH 1

Name: ptweight.jpg
Views: 184
Size: 43.9 KB
Description: GRAPH 3
peterangus is offline Find More Posts by peterangus
Last edited by peterangus; Dec 03, 2013 at 06:08 AM.
Reply With Quote
Sign up now
to remove ads between posts
Old Jan 03, 2010, 03:44 PM
Registered User
Fourdan's Avatar
Antony (France)
Joined Sep 2003
2,915 Posts
Hi Peter
Good presentation
I remark that for your 70%NLS
the ratio PowerIn/motorWeight is 3W/g
(150W In for 50g motor)
It is my upper limit, generally
Louis
Fourdan is offline Find More Posts by Fourdan
Reply With Quote
Reply

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Thrust/weight ratio for seaplane SaulOhio Waterplanes 1 Jun 17, 2007 01:51 PM
Discussion Rule of Thumb for Power to Weight Ratio darkmask Foamies (Kits) 2 Jun 12, 2006 01:54 PM
Best power to weight ratio for a smaller DF 66tbird Electric Ducted Fan Jet Talk 0 Mar 16, 2005 11:32 AM
wing loading/ power to weight ratio to ROW barn buster 50 Electric Plane Talk 0 Jun 20, 2003 10:52 PM
Gear drives effect on power/weight ratio Shakey Jake Power Systems 6 Mar 17, 2002 09:25 AM