How do I use this thing (incidence meter)

[Wyatt]

Hi,
I just got some new toys.A incidence meter ,deflection meter,CG manchine
and a prop balancer.I know how to use all but the incidence meter I got it use no info on it.But would take all the info I can get on all.
Thrust and prop size is something else I`m having trouble understanding.
Thanks
Wyatt

[Ollie]

There are three aerodynamically significant angles. They are the decalage ( angle between the wing chord line and the tail chord line), the angle between the thrust line and the wing chord line and the angle between the thrust line and the horizontal tail chord line.

Incidence is the angle between the chord line of a flying surface and some arbitrary reference line. Because the reference line is arbitrary it may not have much aerodynamic significance unless it coresponds to one of the three aerodynamically significant directions mentioned above. The purpose of an arbitrary reference line is to make it easier to measure the angles between the three aerodynamically significant directions.

The incidence meter has a built in horizontal reference direction provided by a bubble level so that the incidence meter can be used to measure the three aerodynamically significant directions with the aircraft oriented at any arbitrary pitch attitude.

To use the incidence meter, just measure the three significant directions relative to the built in reference and subtract them one from another in pairs to get the three significant angles.

If you are working from plans that use an arbitrary reference line, then block the aircraft up so that the arbitrary reference line corresponding to the plans is horizontal and matches the built in reference of the incidence meter.

Thrust is a force. It can be produced by a propeller that is spinning at a some RPM and flying at some airspeed. The actual value of thrust varies with RPM, prop diameter, prop pitch, porp airfoil, prop blade area, prop chord at each diameter station and aircraft air speed. Static thrust is a lot easier to measure than to calculate. As a practical matter dynamic thrust can only be estimated.

Prop size is roughly specified by two numbers, diameter and pitch. The meaning of diameter is self evident and easily measured directly. The meaning of pitch is the distance that the prop moves ahead in one revolution. Unfortunately the type of pitch specified is usually measured to a reference line tangent to the bottom of the prop airfoil. The second type of pitch is the geometric pitch which is defined by reference of the prop airfoil chord line. The third kind of pitch is the zero thrust pitch which is referenced to the zero lift angle of attack of the prop airfoil. The three types of pitch can differ from each other so much that it is necessary to know the differences to get any sort of accurate idea of why different sizes and manufacturers of props perform the way they do.

[omega blood]

http://www.rcgroups.com/forums/showpost.php?p=1295237&postcount=88

[omega blood]

http://www.rcgroups.com/forums/showpost.php?p=1863581&postcount=6

[Wyatt]

Wow I like it, :D
I see now. It makes sence. Nice plane too.How do you line it up for thrust?

Oillie thanks for all the info.I`ve been tring to find this out for awhile.The last few days I have been asking alot of question .On a few other sites as well.WOW alot of info has come my way. :)
My next "step" is to set down and burn this in to my brain.I`m proud of myself today. Cut all my ribs for the wing on the secound plane.While I was waitting.I thinkin the morning I will finish (or get alot done) on the first.Its ready to set the wing. :eek:
I`m looking forward to flying it.I`m sure my W.W.W.II will be a nicer plane.I`m getting the hang of things. :rolleyes: Wyatts Wild Wings
But I guess I`ll have to post a picture when I`m done.(how do you do that)? :confused:

[omega blood]

Wow I like it, :D
I see now. It makes sence. Nice plane too.How do you line it up for thrust?



I have meter like the one on the picture. If you look at the scale where you read it, to the bottom left there is a notch. Slide in the notch were the prop would go follow the same direction as above for reading the thrust angle and adjust acordingly.

[Wyatt]

Hi,
Well I got it lined out.After I got started the hands on thing started working.It went together realy well.All cross measurments and angle are the same.All the ,chord,and stab.all set at the same level as the thrust.
It went together to good not to have it right.But I could have made a mistake?I set the plane up on a table.And got it where the fuse set level useing a level.My fuse is squared and flat sided.My thrust angle seems to be the same.Then I crossed measured the distance from the RT. wing tip to the left stab. ,,,Left wing tip to the RT. stab. Then the distance from the center of the spinner to the wings tips.
Then I put the incidence meter on the wing,(closer to the fuse ,my wing is flat and has no wash out).I spaced the wing to where the levels matched the one on the fuse and the one on the stab.It didn`t take mush.
This is how I would do a car on a frame rack (many years of exper.)But cars don`t fly.Some wants to .So I explaned what I did in HILLBILLY terms.DO YA THINK I DID IT RIGHT? It does look like it all lined out.
The next stage is to the balancing stand.I seen where to balance I should not have the plane fueled.I have a 8 oz. tank in the front of the plane. These seems to me to this would make a big differnce in the Balancing.??? I still have to build my landing gear.And finish my canopy.
Then FIRE THIS MOTHER UP .......I need to build a engine stand for breaking in.But this is anothe thread.I wished I took pics. w`ll I was doing this.It look like I knew what I was doing. :) :) :) :) :) :) :) :)