News:



  • July 05, 2025, 09:46:34 AM

Login with username, password and session length

Author Topic: Profile fuselage question  (Read 2714 times)

Offline Steven Kientz

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 680
Profile fuselage question
« on: July 23, 2008, 02:19:59 PM »
I was daydreaming at work today,easy to do if you work in a warehouse. Has anyone tried to offset a profile fuselage rather than it being perpendicular to the wing and tail assembly? Wouldn't this do away with engine and rudder offset? Would 2 degrees make the plane to hard to trim? Also, where would you measure the angle from? One end( nose or tail) to the other, or from TE to nose? Since we fly in 1/2 of a sphere( although I have tried to enlarge that, ie CRASH) I know there are differences when compared to full scale and Rc airplanes.Ialso assume the wing and stab need to be parallel? I'm sure someone has tried this.

Thanks

Steve
Steve Kientz
AMA 855912

Offline Jim Oliver

  • 25 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1414
Re: Profile fuselage question
« Reply #1 on: July 23, 2008, 02:50:35 PM »
Hey Steve,

Not to be a smart_______ (you fill in the blank), but get back to work!!  VD~

No more day dreaming!!  n~

Cheers,
Jim
Jim Oliver
AMA 18475

Offline Just One-eye

  • Another Old Fart
  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 198
Re: Profile fuselage question
« Reply #2 on: July 23, 2008, 03:04:31 PM »
Both engine and rudder deflection are unnecessary if the line rake angle and tip weight are correct.


Offline minnesotamodeler

  • 2014 Supporters
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2335
  • Me and my Chief Engineer
    • Minnesotamodeler
Re: Profile fuselage question
« Reply #3 on: July 23, 2008, 03:39:23 PM »
So you have (theoretically) just turned the wing/stab on the fuse, moving the LO guides back in the process...you'd have to move them forward a lot, I think.

I have a combat wing in which I angled the whole motor mount rather than the engine by itself.  Center ribs are angled too.  Didn't like it.  Not sure you can detect it in the pic.
--Ray 
Roseville MN (St. Paul suburb, Arctic Circle)
AMA902472

Offline phil c

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2480
Re: Profile fuselage question
« Reply #4 on: July 23, 2008, 04:27:57 PM »
A while back I built some slow combat planes using a plug in foam wing- it slid into the fuselage opening like an old AJ or Guillow's glider and was held in place by tape.  On occasion the tape would come loose and the fuselage slide off at an angle to the wing, sometimes as much as 20 degrees or more.  It made almost no difference in how the plane flew.  Sometimes the pilot couldn't even tell that the fuse had slipped.  These planes only had a token rudder, a lot like Hunt's Genesis, so the rudder really didn't come into play.  There wasn't any benefit either though, so I wouldn't bother.  Straight and solid is easier to build and troubleshoot.
phil Cartier

Offline john e. holliday

  • 25 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 22989
Re: Profile fuselage question
« Reply #5 on: July 24, 2008, 07:37:45 AM »
Back in the day of VooDoo's, Big Iron's and Winder's I always putin a couple of degrees of offset on the engine pods.  The whole center section was fiber glassed also.  Never worried about planes coming in at me.  I would never off set a full fuselage or profile fuselage airplane.  DOC Holliday
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
AMA 23530  Have fun as I have and I am still breaking a record.

Offline Steven Kientz

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 680
Re: Profile fuselage question
« Reply #6 on: July 24, 2008, 02:42:52 PM »
Was just curious,didn't know if it would be of any benefit or not. Difficult to think about flying(skidding) around a circle. Definitely easier to play with line rake .
I don't daydream at work to often, usually on my toes trying to avoid UNDER TRAINED FORKLIFT  DRIVERS. Can't call them operators, most are lucky to go from point A TO B without hitting something. Hope to change some of this soon, was just qualified as a forklift trainer.

keep the shiny side up,

Steve
Steve Kientz
AMA 855912

Offline Neville Legg

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 589
Re: Profile fuselage question
« Reply #7 on: July 25, 2008, 03:53:30 PM »
Charles Mackay designed a flying wing with the engine pointing about 30 degrees!! out to the line of flight! It was featured in Flying Models in the mid '60's, I think it was called the 'Monster'.  It was a large triangular wing with a small motor in it, flying on long lines, must have had a lot of drag? Can't remember how it flew!

Cheers   Neville
"I think, therefore I have problems"

(not) Descartes

Offline Larry Cunningham

  • Red Hot Lover
  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 855
  • Klaatu barada nikto my ass
    • Stephanie Miller
Re: Profile fuselage question
« Reply #8 on: July 25, 2008, 05:34:48 PM »
Both engine and rudder deflection are unnecessary if the line rake angle and tip weight are correct.


Definitely so. They actually fly best. It may be argued that the engine crankshaft centerline
being offset 1/2 the fuselage thickness from the center might induce a small couple which
tends to nose the ship toward the center of the circle, but I don't think it is measurable in
practice. The effects of drag and weight of the lines surely has a more important effect.

Flying on a tether affects drag and trim already.

L.

"Only learn to seize good fortune, for good fortune is always here." -Goethe
AMA 247439 - '09, '10, '11, '12 and '13 Supporter of this site..

Offline Steven Kientz

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 680
Re: Profile fuselage question
« Reply #9 on: July 26, 2008, 03:53:40 PM »
If I move the leadouts back on my Tutor II I should end up with more line tension, right? That pivots the plane towards the outside of the circle.

Steve
Steve Kientz
AMA 855912

Offline John Miller

  • 25 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1728
Re: Profile fuselage question
« Reply #10 on: July 26, 2008, 04:40:39 PM »
Try moving them forward until you start to lose line tension, then back them up about an 8yh. of an inch.
Getting a line on life. AMA 1601

Offline Larry Cunningham

  • Red Hot Lover
  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 855
  • Klaatu barada nikto my ass
    • Stephanie Miller
Re: Profile fuselage question
« Reply #11 on: July 27, 2008, 09:08:07 AM »
Moving the leadouts forward can help by better trimming the yaw for a circular path
and reducing drag, improving line tension by virtue of centrifugal force (I think). It seems
contrary to logic at first, but when you try it, you'll see.

Building the rudder flat, with just a hint of airfoil on the left side (a la original Nobler),
also seems to help line tension, probably for a similar reason. In fact, as demonstrated
by several prominent builders, a CL stunter doesn't need a rudder. I found out the truth
of that when I nicked the ground on an outside loop on stock Twister, with a (plan setting) large
amount of rudder deflection. The rudder popped off, the ship kept flying, and I immediately
noticed a major improvement in line tension and general flying trim. Afterwards, I cut the
rudder and glued it back straight and back on the ship, and it worked well.

Nature doesn't care about any "notions" of mine or yours, so be sure to see what actually
works. ;->

L.

"It is a capital mistake to theorize before one has data." -Arthur Conan Doyle
AMA 247439 - '09, '10, '11, '12 and '13 Supporter of this site..

Tags: