Go Back  RCU Forums > RC Airplanes > Aerodynamics
 Thrust Line >

Thrust Line

Community
Search
Notices
Aerodynamics Discuss the physics of flight revolving around the aerodynamics and design of aircraft.

Thrust Line

Thread Tools
 
Search this Thread
 
Old 11-30-2009 | 02:30 PM
  #1  
trooper-rat's Avatar
Thread Starter
Junior Member
My Feedback: (4)
 
Joined: Jul 2009
Posts: 17
Likes: 0
Received 0 Likes on 0 Posts
From: Apex, NC
Default Thrust Line

Hello All,

I am completing a Bud Nosen Citabria my father started about 15 years ago. With today's engines, fuel choices, and power applications, the opportunities are limitless as to what
"CAN" be done and what I wish to do.

~cutting to the chase~ I wish to put a 30cc gasser on the aircraft. Albeit, in order to use the aforementioned engine, thecenterline of engine will place the prop shaft at 1/4" above the thrustline of the plans in order to mount the engine within the cowling and aligning the propshaft cut out.

My delima: How catastrophic would this be? The plans also call for (0) zero degree down and/or (0)zero degreeright thrust.

Thank you for your time,
Scott
Old 11-30-2009 | 04:47 PM
  #2  
Senior Member
 
Joined: Dec 2001
Posts: 7,769
Likes: 0
Received 6 Likes on 5 Posts
From: FL
Default RE: Thrust Line

I doubt that it will make a measurable difference in flight characteristics.
Old 11-30-2009 | 06:22 PM
  #3  
Senior Member
 
Joined: Oct 2005
Posts: 11,517
Likes: 0
Received 2 Likes on 2 Posts
From: Near Pfafftown NC
Default RE: Thrust Line

ORIGINAL: trooper-rat
in order to use the aforementioned engine, the centerline of engine will place the prop shaft at 1/4'' above the thrustline of the plans in order to mount the engine within the cowling and aligning the propshaft cut out.

The prop shaft of the engine decides where the engine is mounted.

If the prop shaft is 1/4" too high, mount the engine 1/4" lower.

Whatever............ 1/4" higher or lower won't cause any aero problems. Might not show anything at all.
Old 11-30-2009 | 09:53 PM
  #4  
MTK
Senior Member
 
Joined: May 2004
Posts: 5,386
Likes: 0
Received 1 Like on 1 Post
From: Whippany, NJ
Default RE: Thrust Line


ORIGINAL: trooper-rat

Hello All,

I am completing a Bud Nosen Citabria my father started about 15 years ago. With today's engines, fuel choices, and power applications, the opportunities are limitless as to what
''CAN'' be done and what I wish to do.

~cutting to the chase~ I wish to put a 30cc gasser on the aircraft. Albeit, in order to use the aforementioned engine, the centerline of engine will place the prop shaft at 1/4'' above the thrustline of the plans in order to mount the engine within the cowling and aligning the propshaft cut out.

My delima: How catastrophic would this be? The plans also call for (0) zero degree down and/or (0) zero degree right thrust.

Thank you for your time,
Scott
The Citabria is a high winged sort of aerobatic platform. On this model, 1/4" either high or low won't make much difference....you may want to reduce the dihedral a degree or two, if it has any at all.

On more thoroughbred low winged aerobats at around 1.2 size, 1/4" higher thrust vector will in essence result in a lower wing position relative to thrust, meaning you would likely get a little adverse roll coupling with applied rudder for the given dihedral.

Your Citabria should not exhibit much change with any command

MattK
Old 11-30-2009 | 10:04 PM
  #5  
trooper-rat's Avatar
Thread Starter
Junior Member
My Feedback: (4)
 
Joined: Jul 2009
Posts: 17
Likes: 0
Received 0 Likes on 0 Posts
From: Apex, NC
Default RE: Thrust Line

Thanks everyone for your input. I didn't think the thrustline would be too serious, but I wanted to hear it from others to enforce my decision to continue with the engine choice.

I apprieciate these forums andits members more and more daily!!
Old 12-02-2009 | 05:10 PM
  #6  
rmh's Avatar
rmh
Senior Member
 
Joined: Dec 2001
Posts: 12,630
Likes: 0
Received 4 Likes on 4 Posts
From: , UT
Default RE: Thrust Line

ORIGINAL: trooper-rat

Thanks everyone for your input. I didn't think the thrustline would be too serious, but I wanted to hear it from others to enforce my decision to continue with the engine choice.

I apprieciate these forums and its members more and more daily!!
Some guys put a lot of work into thrust line settings.
Of all th basic settings this one is most tolerant of it's placement or angle
Why?
the speed of the airframe (the models) dictates the actual angle of wing, stab and thrust.
so any setting is a moving target
Where thrust lines really get fussy are setups where the engine is very high above (or far below)the vertical center of drag.
The reason is pretty obvious - the force (thrust is working on a longer moment arm
Old 12-02-2009 | 07:37 PM
  #7  
trooper-rat's Avatar
Thread Starter
Junior Member
My Feedback: (4)
 
Joined: Jul 2009
Posts: 17
Likes: 0
Received 0 Likes on 0 Posts
From: Apex, NC
Default RE: Thrust Line

The thrust line on this kit runs from F1 through the fuse to the exact corner of the empenage at the base of the vertical fin (mounting point of the tail wheel). Again, this will only raise that line about a 1/4" through the entire fuse without any change inlength on the plans. This is not being built as a airbatic (citabria) aircraft. I will be flying this bird in its the most docile regime due to its importance and scale. authenticity.

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



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

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.