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 » Rotorcraft
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Dumb Question

Thread Tools Display Modes
Old December 22nd 06, 02:24 AM posted to rec.aviation.rotorcraft
Stefan Lörchner
external usenet poster
Posts: 8
Default Dumb Question

Why should a ducted fan/rotor not be capable of working in autorotation?
I never heard about that and cannot find a reason.

How could it? With a duct around it, would you not have to descend straight
down? And if you did, would the rotational mass of a rotor that small in

Straight down can be a possibility. But if you can fly the thing, you
can also tilt the thrust vectors. So just tilt it so that the airflow
matches airspeed like in a heli.

diameter, and designed to work at such a high rpm, store enough energy in
free fall, to stop your descent when you applied collective to land?

That's a design issue since it is not free fall. Otherwise it wouldn't
be autorotation. The rotors/fans would of course have a windmilling
braking effect. And certainly, the inertia has to be sufficient to allow
smooth and preferably save touchdown as should be the case in every

Smaller and faster rotors are less effective and therefore need more
descent rate (more power). That's fact, too. Compare the sink rate in
autorotation of a Hughes 500 and a R44 (or the HV diagrams).

Old December 24th 06, 07:46 PM posted to rec.aviation.rotorcraft
external usenet poster
Posts: 37
Default Dumb Question

Stefan Lörchner wrote:
But an interesting question is why nobody ever tried a supersonic rotor.
Maybe it's easier to fold or stop the rotor than to make it strong
enough and still efficient for sub- and supersonic speeds.

Retreating blade stall.



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
DUMB ROOKIE QUESTION Travis Beach Soaring 10 November 7th 06 08:28 PM
stupid question JaKoB General Aviation 2 November 9th 04 10:48 AM
A question on Airworthiness Inspection Dave S Home Built 1 August 10th 04 05:07 AM
Dumb Transponder Question! John P Owning 2 March 30th 04 01:26 AM
Partnership Question Harry Gordon Owning 4 August 16th 03 11:23 PM

All times are GMT +1. The time now is 11:13 PM.

Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
Copyright ©2004-2022 AviationBanter.
The comments are property of their posters.