hrrcflyer

Sorry to be a little off topic, but I think you guys need to go to one of Zor's posts and hit the little red hand at the bottom and block his posts like I did about a year ago. That way you won't have to put up with his BS............................[:'(]

Take care,
David

MTK

Hi BillS,

4 degrees downthrust is likely okay for certain models such as high wing, high lift undercambered foil. Keeps that type of model from zooming.

In the case of the Kougar tho, it is a symetrically foiled sport model intended for a wider flight envelope. Itwould be better if set-up with zero on stab and engine and just a triffle +incidence on wing. Everything will improve. Locating the CG at 25%-30% of the MAC would beanother adjustment I'd make.....

One thing I'd suggest regarding using shims under the soft wheels, you might consider not doing it that way. Reason is that any additional weight (adding the I Meter) will squish the soft foam and throw your measurements off. It would be better if you shimmed the fuse directly. The I meter will produce adequate results as long as you are certain the needle doesn't stick and model doesn't move when youinstall the meter.

If you have a large enough, known flat surface to work with, and IF (big IF) you are not satisfied with the results from an I meter, let me suggest using a non contact meter such as a Height Gauge. It requires that you locate the airfoil centers precisely and marking with a fine point pencil or marker. A Height Gauge requires a flat reference surface to work precisely. Properly used, it can produce and reproduce any fractional angular adjustment one needs. I developed this technique eons agoto set up my precision birds.

Regarding angles, here's a simple way to remember how much slope results in 1 degree.....just remember the digits 1 and 4.A 1/4" difference in 14" of span is equal to 1 degree. In other words, for a 14" prop, the right tip as measured from the fin post should be 1/4" shorter than the left, for 1 degree of right thrust. Few things we do come out exactly at 14" of course, but as a rule of thumbit should help you gauge accordingly

But again, in your application, the I meter is probably adequate

Zor

Bill,

It is always nice to read how someone proceeds (method) to accomplish a task.

Complementing your post ___

My dinner table is flat and horizontal. I sit my model on it with the main gear touching the table surface; no shims under the wheels. I then use anything suitable to make the reference line parallel to the table surface. We may call those items "shims" if we like.

I then make my measurements to an accuracy of 1/64 of an inch and make my calculations.
Results are the incidence of the main wing(s) and stabilizer and the decalage between the main wings of a biplane or sesquiplane and the longitudinal dihedral (decalage of main wings to stabilizer).

Any commercial instrument should be checked for accuracy. Even voltmeters have variations.
Example: It is often useful to know that accuracy when measuring battery packs voltage to guess its degree of charge. I always have a laugh looking at a thermometer with a digital readout with one decimal ( 1/10 of a degree) when the degree digit is 2 or 4 degrees out of reality.

Best to you from Zor

vicman

My Feedback: (10)

How have I been lucky enough to avoid your nonsense posts for 6 years?[&:]

karolh

How sure are you that the measuring device you are using to measure to within 1/64th inch is in fact an accurate measuring instrument as you seem to think that most anything that others use has some inbuilt inaccuracy .... just wondering so no need for you to answer.

sensei

Zor is the best!

vicman

My Feedback: (10)

The height gage post above is an excellent post. I have used that method in the past but had to move on to better tech once I started building V-tail racers.

Again off topic, I feel so dirty.[X(]

Zor

A 12 inches or 18 inches stainless steel rule accuracy depends only on the ability of the individual to read it.
I know many people that cannot read a regular ruler to 1 /16 of an inch.

We can calibrate measuring instruments to a satisfactory accuracy against a known referecnce.
So we can check the calibrationn of an incidence meter against a physical set up done by mathematics.

I certainly realize that many hobbyists just hate mathematics and evendislikepeople using them thus some comments in the last few postings.

My feelings are that calibration needs to be accurate only to a practical accuracy for the task being done.

Zor

vicman

My Feedback: (10)

I live in a 5 place decimal world to make a living and you are bragging about how smart you are operating within .016. I use a scale that reads .01 for a rough saw cut and make a good buck doing it. To translate your lunacy to someone trying to get an old model to trim right is out of the realm of reason. Listen to yourself and ask if Mr. Starrett his bad self didn't use a tolerance when making the best machinist scales ever.
Double talk aside you have not given a logical track to follow yet!

Step away from the keyboard and learn how to do a glue joint without 20X the amount of glue needed and learn that less is better, posting here included. Don't ask me to show you what I build either. Just look in your telescope (if you can believe it is accurate enough) at the space station. Yeah, I made parts for that too.


Edited to stop name calling. I should not have done that. Vic

Zor

Yes Bob, I built my own prop balancer andI can give a 15 x 8 two blade prop a hand (finger) fast kick and it will take over 5 minutes to stop turning. Just an indication of low support friction.

I also built a CG locator with two metal knife edge support; one on each side of the fuselage.
I can find the verical line on which the CG is located with an accuracy that is the ability to read a ruler.
This locator has sufficient contact area to avoid damaging the structure and finish at the points of support.
I also sometime use the string loop method as a back up.

I enjoy this type of activity and it does not bother anyone else.

Zor

Zor

vicman

Readers can judge the difference between us.

Zor

EJWash1

My Feedback: (3)

YES! Smart to stay out of deep waters.

EJWash1

My Feedback: (3)

Okay zor. Here's your chance to put your "ability to visualize" in regards to setting incidence as a builder to example.

Zor

A Height Gauge can be a simple ruler readable to an accuracy of 1/64 inchasI referred to in neaby postings.

Zor

Roguedog

Bill,

Make the wing incidence the same as the stab. Then adjust the engine thrust .

The followingis not a trick, but a sequece of flight tests to perfect your planes trim, incidence, CG, engine thrust etc. if you really want to correct the planes defeats. Use if needed.

Regardless of what the stated engine thrust, wing incidence and stab incidence say on the plansflight trimming is the only way perfect the planes flight characteristics.

If you already understand flight trimming addthis chart to you collection. If not the chart below will blow your mind as far as how much better your palne will fly. There are several Flight Trimming Charts or Guides available inthe forums and on the web.The static measuring offered on plans is great to get you started but the only accurate way to perfect your planes trimis through actual flying or "Flight Trimming."All that's required is to learn how to check your plane against one of the charts while flying it.

As an example i had purchased a Kaos of craigslist that was badly trimmed when built. Thefirewallhad 4 degrees of downthrust. The wing had +1.5 degree incidence on one side, and -1.8 on the other. The stab was misaligned badly as well with one tipbeing closer to wing than the other. I was told that the Kaos was not designed for knide edge flight but after using the chart below. I have a very well trimmed plane that acutually flies in knife edge with ease.

Too get it there I firsthad to cut off the stab with a razor saw to align it correctly to the wing and set it to 0 degree incidence. The wing was fixed by using my heat gun to shrink the Monokote alternately on each side. Then I startedthe flight trimming tests. Checked the CG first and got it nailed based on the tests.Next, was the decalage (incidence.) I had to adjust thewing incidence several times and it was finallyset at0 degrees, once again based on the tests.Next , through thetests the engine thrust was also set at0 degrees. I was also able to determing that indeed the Kaos did not have enough rudder area and stab height for knife egde flight. That was fixed by adding a 1"h x 4"L small triangle stab on the bottom of the fuse and 1" as well to thebottom of the rudder.

Here's the first one I ever used. It's from the Futaba 8uafs 8uaps 8uhfs 8uhps radio manual. It says Pattern Aircraft Flight Trimming Chart buttest 2 really applies to the Old Classic Pattern planes. Other thanthatall the other tests are usefull for all planes. Someoneelse said to start with CG and I agree so for the chart below start a No. 1, ignore No. 2, and switch tests 3 and 4so you start with CG than goto Decalage (incidence).

If your plane is flyable spend a day learning to fly the these sequencesto check out your planes flight characteristics against the chart before youmake any other changes to your plane.

Zor

Hi folks,

Here are simple calculations.

Not knowing the length of the stabilizer chord, I calculated for 4 chords.
3, 6, 9 and 12 inches.
The dimensions below can easily be interpolated for the actual measured chord of the stabilizer.

First assure that the referencel line is horizonal as practical as you can make it and parallel to the base surface upon which the ruler can sit on (vertical gauge device).

For a 1 (one) degree of incidence ___At left the chord ___ at right the difference between the leading edge and the trailing edge. The leading edge higher for positive incidence. All dimensions are inches.

3 ...... 0.0524
6 ...... 0.1047
9 ...... 0.1571
12 .... 0.2095

For a 2 1/2 (two and one half) degrees

3 ...... 0.1310
6 ...... 0.2620
9 ...... 0.3930
12 .... 0.5239

Above dimensions can be converted to sixty-fourth by multiplying them by 64
Example: 2 1/2 deg incidence and a 9" chord becomes0.3930 x 64 = 25.15 / 64 (use 25)
same in 32nd becomes 0.3930 x 32 = 12.58 (use 12 1/2 / 32nd).

Your accuracy is determined by the ruler reading. It is not difficult to even read 1/128 of an inch using a good steel ruler.

Zor


Edited to correct "pracical" to "practicle".

EJWash1

My Feedback: (3)

You have notwalked us through how to apply what you've come-up with to attaching my horizontal stab to my Waco - as I asked you to. How do I prepare the stabilizer platform surface using your calculations?

Zor

Vic,

I have no doubt you are a nice fellow but you have a tendency to exagerate or misjudge the proportions.
The photos in post #41 are components of an 11 lbs model that used less then 4 tubes of Sig-Ment glue. I proved to myself that the cured glue weight less than 4 ounces of weight. ( less than 2.27% of the flying weight ).

I regret that the exageration about the glue makes mewonder aboutthe rest of the posting.

Let us be realistic.

Zor

Edited to add the post #41 to ease the readers who may wish to see the pictures referred to.
End

EJWash1

My Feedback: (3)

zor, back to the thread topic. When can we expect your demonstration to back-up what you posted?

Zor

Hello readers,

Back to incidence measurements and method.

I am having fun figuring things out.
I am not addresiing to anyone that mainly enjoys being nasty to me.
It is in his nature and his postings do not bother me.
He is now acting as if he needs the knowledge and perhaps he does.

I made a drawing backing the calculations. I do not know how well it will show but I will find out after posting.

Iexpect that fellows can read a ruler to an accuracy of 1/64 of an inch and I showed how to convert decimals to fractions.

Le us see how the drawing appears.

Zor

EJWash1

My Feedback: (3)

...

karolh

You guys remind me of the story of the ram that kept butting his head against the dam in the hope of butting it down and in this senario Zor is the dam. In this particular instance he will never see your point of view and all you will end up with is a headache, so my advice is leave well alone.

EJWash1

My Feedback: (3)

Karolh,

karolh

Point taken and best of luck to you all, meanwhile I'll just be a silent observer.

BillS

Post #70. Which CAD program were you using?

Bill