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Fuselage?? - 2/13/2008 3:48:18 PM   
rc flyer uk


 

Posts: 90
Joined: 1/19/2004
From: Whyteleafe, UNITED KINGDOM
Status: offline 		I am a third year aerospace engineering student and am currently designing and building a UAV.

The design is basically a traditional glider which has a pod slung under the CG to carry equipment.

I have already designed the wing, and have now come to deciding on the length of the fuselage and wing placement.

I am aware the fuselage is nothing more than a lever to mount flying surfaces on, and that the only consideration needed is for length of the fore or nose moment so the aircraft will ballance with no ballast! But was wondering if anyone could point me the direction of any information (websites, books, journals etc) as to the theroy of fuselage design as i have been unable to find anything! Also any information about wing placement would be gratefull!

Many Thanks

Rob
       Post #: 1

RE: Fuselage?? - 2/13/2008 7:10:22 PM   
Campgems


 

Posts: 1805
Joined: 2/18/2006
From: Arroyo Grande, CA, USA
Status: offline 		Rob, see if you can find some back issues of RC Model World magazine. It is a UK magazine and one of the best I've seen. They usualy have an article in each issue about gliders. They will give you a lot of construction ideas. Also the authors usually have their Emails included, so you could contact them.

Things to consider are the linkages to the tail surfaces. As you want to keep you weight as near to the CG as possible, you will want light weight linkages. As the strains in a glider are no where near those in powered planes, you can get by with some really light linkage. If you incorporate flying elevator and a counter blalanced rudder, the stress is reduced again.

I have three gliders now, and the all use a simple balsa box for the fuselage. A lot of the newer, sporty hand launch gliders are use carbon fiber tubes aft the wings.

Our club built and maintains a flying field on Cal Poly land that is used to support the schools Aero Space program. We get some interesting planes out there at times. There seems to be a lot of UAV interest now. The projects we've seen though are powered aircraft.

Don
WWW.Sloflyers.com

(in reply to rc flyer uk)
       Post #: 2

RE: Fuselage?? - 2/14/2008 1:47:33 AM   
iron eagel



Posts: 1212
Joined: 7/15/2004
From: Middleboro, MA, USA
Status: offline 		Rob,
There are several books that do have some basic information about fuselage design.
One is Andy Lennon's "Basics of R/c Model Aircraft Design". Another book worth having is Martin Simons' "Model Aircraft Aerodynamics" (which I have just started to read). And another that might contain helpful information (I just ordered) is one by Jack Norris and others that is a two for one deal "Propellers The first and final explanation/The Logic of flight".

Also check out: http://www.airfieldmodels.com
Lots of thoughts on building and design there.

My feeling is the that a lightweight, rigid structure, that puts drag reduction at the top of the list is probably the most important design considerations. Also second to this would be reduction of turbulent airflow caused by the wing fuselage junctions and interference drag.

It is my understanding that a round (from the front) elongated reflexed teardrop shape is the best choice for a low drag fuselage...


< Message edited by iron eagel -- 2/14/2008 1:49:24 AM >

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The Wrights never crashed, they only had hard landings. I 've had some hard landings myself. AMA EAA AOPA revver #185

(in reply to rc flyer uk)
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RE: Fuselage?? - 2/14/2008 2:57:03 AM   
HighPlains


 

Posts: 2640
Joined: 3/2/2003
From: Over da rainbow, KS, USA
Status: offline 		Rob, welcome to engineering now that you have finished basic math, physics and English classes. There seems to be very few books on fuselage design, in particular ones that concern themselfs on low drag. I doubt the books mentioned above have anything more than a mention in passing on the subject, yet finding material on airfoils is everywhere.

One book that I have found to have the entire aircraft covered is a little known work by Bruce Carmichael, call "Personal Aircraft Drag Reduction". Finding a copy might be difficult, since it was published by Mr. Carmichael and sold by him in the late '90's. As such, it is not a polished manuscript, but rather the result of a lifetimes work, and a somewhat difficult read. It does contain a huge volume of of references on each subject ranging from NACA studies from the 30's to articles in soaring magazines, so he tried to provide the entire body of work in drag reduction for the last 50-60 years. Much of the work of the Germans and British researchers is also referenced.

Edited to include:

I have found out that it is still available at the following:

http://www.aircraftspruce.com/pdf/2007Individual/Cat07688.pdf


A short article by Bruce Carmichael may be read here:

http://www.glidingmagazine.com/FeatureArticle.asp?id=289

< Message edited by HighPlains -- 2/14/2008 3:05:43 AM >

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In politics if you want anything said, ask a man. If you want anything done, ask a woman - Margaret Thatcher

(in reply to iron eagel)
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RE: Fuselage?? - 2/14/2008 3:34:14 AM   
combatpigg



Posts: 9593
Joined: 11/22/2003
From: arlington, WA, USA
Status: offline 		HP, thanks for sharing those articles. I'm going to have to make one of those wave gauges now, plus stock up on more sandpaper.

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Led Zeppelin is NOT "old fogie" music.

(in reply to HighPlains)
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RE: Fuselage?? - 2/14/2008 4:09:37 AM   
HighPlains


 

Posts: 2640
Joined: 3/2/2003
From: Over da rainbow, KS, USA
Status: offline 		CP, the first third to half of the airfoil means everything. Gauges for the airfoil nose profile really makes a difference too. Also take the wing outside and use a point source to illuminate the wing. (OK, I'm talking about the sun, but where you live that might be a problem. In most places it is a big yellow ball that appears in the sky. Google it, you will be surprised.)

Anyway, with the sun in the late or early sky, hold the wing between you and the sun and slowly rotate it watching the shadow move across the wing chord. It should move smoothly, if not, you have a flat spot.

Sanding blocks are the key to shaping the airfoil. The 3M rubber block works well, and I'd bet you got half a dozen.

_____________________________

In politics if you want anything said, ask a man. If you want anything done, ask a woman - Margaret Thatcher

(in reply to combatpigg)
       Post #: 6

RE: Fuselage?? - 2/14/2008 4:27:06 AM   
iron eagel



Posts: 1212
Joined: 7/15/2004
From: Middleboro, MA, USA
Status: offline 		High plains thanks for that info!

Looks like I am going to build one of those gauges myself, plus a lot of sanding....

< Message edited by iron eagel -- 2/14/2008 4:31:56 AM >

_____________________________

The Wrights never crashed, they only had hard landings. I 've had some hard landings myself. AMA EAA AOPA revver #185

(in reply to HighPlains)
       Post #: 7

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