A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Soaring
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Electric Duct Fan (EDF) Self-Launch Glider?



 
 
Thread Tools Display Modes
  #1  
Old January 18th 11, 02:07 AM posted to rec.aviation.soaring
Bruce Hoult
external usenet poster
 
Posts: 961
Default Electric Duct Fan (EDF) Self-Launch Glider?

On Jan 18, 11:20*am, CLewis95 wrote:
This EDF approach may never compete commercially or performance wise
with Jet Turbine or current conventional gas or electric prop
systems ... I'm just curious if adapting small EDF's could achieve the
very limited goals in my proposed scenario.

- 60lbs Thrust
- 10 minute duration (no reserve)
- Climb from 1,000' MSL to 1,500' AGL
- Using Paved Runway
- No taxi .. prepositioned on runway
- No tailwind component

While certainly not a feasible commercial solution .. it would be a
really neat experiment


It seems to me to be far too little thrust to be useful, except as a
sustainer.

Back in 2000 I ran some calculations for various thrust levels for
glider takeoff using engines of a type where the thrust doesn't vary
with speed (i.e. rockets and, to a large extent, jets):

http://groups.google.com/group/rec.a...484c08689379af

At the time I was not aware of any jet or rocket-power gliders, but
there are now quite a number. I concluded that anything from 100 kg to
250 kg (220 - 550 lbf) of thrust looked very usable.

I see the "BonusJet" in fact has 240 lbf of thrust on a two seat
glider.

Bob Carlton has 225 lbf on his Super Salto. His earlier Silent had
twin 45 lbf engines for 90 lbf total. It obviously worked, but the
videos I've seen make the takeoff look pretty anaemic. I can only
imagine what it would be like with only 60 lbf!

I think these machines verify that my calculations in 2000 were in the
ballpark.

My constant thrust calculations are not as relevant to a prop or
ducted fan where the static thrust is quite a bit higher than the
thrust at 50 or 60 knots, and they're really starting to drop off
after 100 knots.

One conclusion that will still be relevant is that you use less total
energy for the launch if you have a reasonable level of thrust. WIth
low thrust you spend so much more time dragging the aircraft through
the air that you use a lot more energy in total -- my figures showed
17% more fuel needed with 50 kgf (110 lbf) of thrust compared to 100
kgf (220 lbf). WIth only 60 lbf available it would be a lot higher
again, because you'd be using a substantial proportion of the
available thrust just to fly straight and level. 120 lbf for 5
minutes or 180 lbf for 3m20 would be much more useful than 60 lbf for
10 minutes.
 




Thread Tools
Display Modes

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

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Electric motor for hang glider Legend Length Home Built 11 August 27th 09 02:14 AM
Thor Agena launch vehicle with the SERT-2 (Space Electric Rocket Test-2) 700204 9139576.jpg [email protected] Aviation Photos 0 April 12th 07 01:47 AM
Electric Glider Mal Soaring 20 November 2nd 05 10:46 PM
Electric self-launch sailplane CH Soaring 2 September 14th 03 01:49 AM
Glider rocket launch Jim Culp Soaring 1 September 7th 03 07:18 PM


All times are GMT +1. The time now is 07:21 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 AviationBanter.
The comments are property of their posters.