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1 degree of incidence or none - 9/24/2007 10:44:28 PM   
AEROMASTER RCU


 

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From: FARMERSVILLE , TX, USA
Status: offline 		WHILE BUILDING THE TOPFLIGHT STINSON RELIANT SR-9 THE OLD INCIDENCE PROBLEM CAME UP AND ON THE PLANS IT SAID TO SET IT UP WITH +1 DEGREE INCIDENCE.SHOULD IT BE THAT CLOSE? I MEAN AFTER ALL IT IS JUST A MODEL AND I DON'T THINK THAT IF YOU MISS IT +OR- A DEGREE IT WILL CHANGE ANYTHING.
I WILL SAY THAT I ORDERED THE HORIZON HOBBY DIGITAL INCIDENCE METER AND BRACKETS TO MOUNT ON THE WING AND WITH MY LUCK THE METER DID NOT WORK SO I HAD TO SEND IT BACK.
AT THIS POINT I NEEDED TO GET ON WITH THE SET UP OF THE WING SO I USED A TRANSIT TO SET IT UP AND NOW I AM WITHIN .008 OF BEING ON 0 DEGREES.
BOY,WHAT A OVER KILL !


IF YOU USE ENOUGH GLUE!!!!
AEROMASTER RCU
       Post #: 1

RE: 1 degree of incidence or none - 9/24/2007 11:43:46 PM   
Mike Connor



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Joined: 1/10/2002
From: Tulsa, OK, USA
Status: offline 		If it calls for incidence there is probably a reason. I would set it close and trim can take care of the rest. It may be a difference of flying good and flying very good.

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RE: 1 degree of incidence or none - 9/25/2007 5:11:34 AM   
AUTiger


 

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Joined: 12/13/2004
From: Franklin, TN, USA
Status: offline 		Wing incidence is typically determined through wind tunnel testing and is designed to minimize drag at a certain operating condition (i.e. cruise flight). It's typically determined through wind tunnel testing. and for GA or Homebuilts is usually around 2 deg. and 1 deg. for transport aircraft.

Because your model is based on the real model, I'm assuming that the wing incidence is only specified because that's what the full scale aircraft uses. Like Mike Connor said, just try to get it as close to 1 deg. as possible (if you're gonna build it, might as well build it right). Within reason, you shouldn't notice any difference in flight characteristics if you're only a degree or so off.

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RE: 1 degree of incidence or none - 9/25/2007 3:46:52 PM   
Bax


 

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From: Champaign, IL, USA
Status: offline 		With models, a good designer will build and fly it and try different setups to see which works the best. Exact scale positioning is secondary, especially in "Sport Scale" models. Flying characteristics are paramount. The 1 degree angle of incidence of the wing on the Top Flite Stinson Reliant was determined by flight testing. A fiddle here, an adjustment there, and the model was flying as the designer wanted it to fly. Get the different flight surfaces as close to the specifications as possible, and your model will fly as intended by the designer.

One degree DOES make a difference between flying "OK" and flying "Great".

< Message edited by Bax -- 9/25/2007 3:47:04 PM >

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RE: 1 degree of incidence or none - 9/25/2007 6:35:33 PM   
AEROMASTER RCU


 

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From: FARMERSVILLE , TX, USA
Status: offline 		THANKS FOR ALL OF YOUR INPUT (ALL OF YOU).THE ONLY THING WITH A WING TUBE AND BOLTED TO THE FUSE,YOU CAN'T CHANGE THE INCIDENCE AFTER YOU HAVE BOLTED THE WINGS TO THE FUSE,SO I AM HOPING THAT THE + .018 WILL FIGURE OUT TO BE ABOUT 1 DEGREE.
LIKE I SAID I HAD TO USE A MACHINIST TRANSIT BECAUSE MY OTHER TOOL WAS DEFECTIVE.


AEROMASTER RCU

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RE: 1 degree of incidence or none - 9/25/2007 10:39:38 PM   
da Rock



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quote:

ORIGINAL: AEROMASTER RCU
THE ONLY THING WITH A WING TUBE AND BOLTED TO THE FUSE,YOU CAN'T CHANGE THE INCIDENCE AFTER YOU HAVE BOLTED THE WINGS TO THE FUSE,


Actually, you can. Move the bolt hole. It's actually pretty easy.

With a round wood rasp, file the hole toward the way you want it moved. Check the incidence as you go until you've got that perfect. Then fill the useless part of the hole with anything. Epoxying in some scrap wood works. You don't have to be neat because after the epoxy cures, you clean the hole up to be nice and pretty. The wood rasp does a good job of this too.

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RE: 1 degree of incidence or none - 9/25/2007 11:25:22 PM   
AEROMASTER RCU


 

Posts: 8
Joined: 1/8/2002
From: FARMERSVILLE , TX, USA
Status: offline 		THANKS FOR YOUR INPUT

AEROMASTER RCU

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RE: 1 degree of incidence or none - 9/25/2007 11:37:03 PM   
Mike Connor



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quote:

ORIGINAL: AEROMASTER RCU

....SO I AM HOPING THAT THE + .018 WILL FIGURE OUT TO BE ABOUT 1 DEGREE...
AEROMASTER RCU

Is the + .018 inches or degrees? Not sure I understand what you are saying but raising the front or back of a 14" cord wing 1/4" would change the incidence about 1 degree according to my CAD program

Edit - Change 1/8" to 1/4"

< Message edited by Mike Connor -- 9/25/2007 11:40:55 PM >

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RE: 1 degree of incidence or none - 9/26/2007 12:32:13 AM   
fredsedno


 

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From: Winchendon, MA, USA
Status: offline 		Gentlemen,
If my trigonometry is still correct :the sine of 1* for 1" length is .0174 thousandths or for a 14" chord[14x.0174] which would be .2436, just about 1/4" [.250]

still not the sharpest tack in the box,Fredsedno

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RE: 1 degree of incidence or none - 9/26/2007 2:21:51 AM   
Mike Connor



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quote:

ORIGINAL: fredsedno

Gentlemen,
If my trigonometry is still correct :the sine of 1* for 1" length is .0174 thousandths or for a 14" chord[14x.0174] which would be .2436, just about 1/4" [.250]

still not the sharpest tack in the box,Fredsedno

Did you just repeat what I just said or am I not the sharpest tack in the box?

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RE: 1 degree of incidence or none - 9/26/2007 2:55:54 AM   
da Rock



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From: western, NC, USA
Status: offline 		Yup.
So it's probably right, right.

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RE: 1 degree of incidence or none - 9/26/2007 1:47:13 PM   
beepee


 

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From: Dubai, UNITED ARAB EMIRATES
Status: offline 		One degree of variance in the wing incidence will not affect flight enough to notice for a sport flyer. One degree of variance in the relative incidences of the horizontal stabilizer and the wing will make a difference. If you can vary the tail incidence, just keep its relationship with the wing consistent with the plans and you should be fine.

Bedford

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RE: 1 degree of incidence or none - 9/26/2007 2:47:28 PM   
AEROMASTER RCU


 

Posts: 8
Joined: 1/8/2002
From: FARMERSVILLE , TX, USA
Status: offline 		MIKE;
THE MEASUREMENT IS 18 THOUSANDS BECAUSE I HAVE A BRUNSON 75 H MACHINIST TRANSIT THAT WAS USED IN THE AIRCRAFT INDUSTRIES AND HAS A ADJUSTABLE DIAL IN THOUSANDS. I GUESS THAT IS A OVER KILL BUT I HAD THIS AND I DID NOT HAVE A INCIDENCE METER.

THE HORIZ.STAB WAS ZERO WHEN I DID THE MEASURMENT AND THE HORIZON INCIDENCE MOUNTING BRACKETS WERE USED TO SET A SCALE ON TO GET THE MEASURMENT.
BETTER THAN GUESSING!
AEROMASTER RCU

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RE: 1 degree of incidence or none - 9/26/2007 4:07:38 PM   
Mike Connor



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From: Tulsa, OK, USA
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quote:

ORIGINAL: AEROMASTER RCU

MIKE;
THE MEASUREMENT IS 18 THOUSANDS BECAUSE I HAVE A BRUNSON 75 H MACHINIST TRANSIT THAT WAS USED IN THE AIRCRAFT INDUSTRIES AND HAS A ADJUSTABLE DIAL IN THOUSANDS. I GUESS THAT IS A OVER KILL BUT I HAD THIS AND I DID NOT HAVE A INCIDENCE METER.

THE HORIZ.STAB WAS ZERO WHEN I DID THE MEASURMENT AND THE HORIZON INCIDENCE MOUNTING BRACKETS WERE USED TO SET A SCALE ON TO GET THE MEASURMENT.
BETTER THAN GUESSING!
AEROMASTER RCU

It sounds to me like you have an excellent incidence meter. With fredsedno's #.s and your transit you should be able to set it perfect.

beepee,
Wouldn't changing the incidence in relationship to the fuse also change the incidence in relationship to the H-Stab? Maybe I am not understanding you.

< Message edited by Mike Connor -- 9/26/2007 4:08:28 PM >

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RE: 1 degree of incidence or none - 9/26/2007 7:12:20 PM   
Flypaper 2



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From: Kingston, ON, CANADA
Status: offline 		I think it has a lot to do with keeping the fuse. centre line in line with the line of flight. Probably determined to be at cruising speed. Line of flight would be the least drag. I've seen a few planes flying set at 0 incidence and they look like they're flying up hill. I imagine wing loading has a lot to do with it too. Remember seeing movies of B 17s flying in formation and looking out the windscreen at the guy next to you and seeing the wing incidence of his plane. Mind you he's carrying a few tons of bombs. Just a few observations.
Gord

< Message edited by Flypaper 2 -- 9/26/2007 7:13:07 PM >

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RE: 1 degree of incidence or none - 9/26/2007 9:50:11 PM   
fredsedno


 

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From: Winchendon, MA, USA
Status: offline 		Nah, I,m not the sharpest tack.
Never heard of the Brunton you mention,however, I did spend 42 yrs.manufacturing& assisting in tooling Boeing,Grumman, G.E.,Utica Forge,Pratt&Whitney, etc. Routinely worked to 5 decimal places. Sine of 1*[.01745] was obtained from Wolf&Phelps Machinists Hand Book.
As was stated above, .018 is plenty close enough.

Yup,not the sharpest tack[me],Fredsedno

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