Matronics Email Lists Forum Index Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

thrustline

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> Kolb-List
View previous topic :: View next topic  
Author Message
phcpilot



Joined: 24 May 2016
Posts: 16

PostPosted: Tue Oct 05, 2021 3:20 am    Post subject: thrustline Reply with quote

Re:: 10:48:03 PM PST USSubject: Re: Reducing power on take off versus thrust line.From: "chic" <gcechini(at)msn.com (gcechini(at)msn.com)>Okay, so I am a little confused here..... If I raise (just) the rear of the engineon my Firestar 2 for more prop clearance off the boom tube, am I adding positivelyor negatively to the thrust

Raising just the back motor mount so that the thrustline points lower at the front is down thrust which results in an in flight nose up force..


- The Matronics Kolb-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Kolb-List
Back to top
View user's profile Send private message
Richard Pike



Joined: 09 Jan 2006
Posts: 1649
Location: Blountville, Tennessee

PostPosted: Tue Oct 05, 2021 6:48 am    Post subject: Re: thrustline Reply with quote

Correct.
Don't know what you call it, but picture progressively lowering the rear motor mount (pretend that prop length is not a problem) and you can see that eventually your thrust line is going to want to make the airplane just do outside loops. Obvious exaggeration, but you get the idea.
When I went from a 68" prop to a 72" prop, I had to raise the engine to get prop clearance, and also ended up adding two extra washers under the rear motor mounts, working on trim. So the rear of the engine is now about 1/8" higher than the front. But subject to change.


- The Matronics Kolb-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Kolb-List

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.
Back to top
View user's profile Send private message Send e-mail Visit poster's website
neilsenrm(at)gmail.com
Guest





PostPosted: Tue Oct 05, 2021 7:56 am    Post subject: thrustline Reply with quote

I am concerned people might not understand the negative impact of using thrust to counter power induced pitch changes.
First, your effective thrust will be reduced. The impact is related to total thrust and the amount of change of thrust line. 
Second, the down thrust needs to be countered by increasing the angle of attack of the wings which adds drag and increased stall speed.
What is the total impact? Really hard to say but just grabbing an unrealistic number out of the air does a disservice to our readers. There have been a lot of smart people designing and building Kolb airplanes for a lot of years. If it was beneficial and that easy everyone would be flying our planes that way from the very start.
Rick Neilsen
Redrive VW Powered MKIIIC
On Tue, Oct 5, 2021 at 7:22 AM Peter Cowan <cowan.phc(at)gmail.com (cowan.phc(at)gmail.com)> wrote:

Quote:
Re:: 10:48:03 PM PST USSubject: Kolb-List: Re: Reducing power on take off versus thrust line.From: "chic" <gcechini(at)msn.com (gcechini(at)msn.com)>Okay, so I am a little confused here..... If I raise (just) the rear of the engineon my Firestar 2 for more prop clearance off the boom tube, am I adding positivelyor negatively to the thrust

Raising just the back motor mount so that the thrustline points lower at the front is down thrust which results in an in flight nose up force..



- The Matronics Kolb-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Kolb-List
Back to top
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> Kolb-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group