Calling all bookworms... :)

[Gyro-nut]

Hello all,
I'm hoping to gain some insight into the formulas I would need to calculate the hang angle of the gyro (or more specifically, the CG limits in inches from the datum).
Here's what I have thus far:
Empty weight: 538 lbs
Empty Weight CG (datum at the nose of the aircraft): 95"

The only W&B criteria is 9 degress +/- 2 degrees nose down.
With me in the front (195 lbs); it's right around 10.5 degrees nose down with a 50.5" arm
The passenger seat is very close to the CG, so weight there doesn't effect it by much. Arm of 87"

What I would like to calculate is the actual limits in inches based off the current data.... I'm speculating there is a formula that would calculate the hang angle and allow me to back into the CG limits for my W&B sheet.

Hope this all makes sense.

Jim A.

 

[bryancobb]

That formula you are seeking will be different for each aircraft, so you have to determine CG Limits, experimentally.
If you occupy the front seat while it's hanging, your assistant could add aft tail weight until you have 9 Deg. nose down. Then
calculate how much total takeoff-moment that is. Then take away some of the tail weight away until you have 11Deg. nose down and calculate
that total takeoff-moment. Then lastly, put all the tail weight back on and continue adding until you have 7 Deg. nose down and calculate that total takeoff-moment.
After you fill out the table below before each flight, the total takeoff moment ...
MUST FALL BETWEEN THE 7 DEG. AND THE 11 DEG. HANGING MOMENTS WHEN YOU WAS IN THE FRONT SEAT

 

[Gyro-nut]

That formula you are seeking will be different for each aircraft, so you have to determine CG Limits, experimentally.
If you occupy the front seat while it's hanging, your assistant could add aft tail weight until you have 9 Deg. nose down. Then
calculate how much total takeoff-moment that is. Then take away some of the tail weight away until you have 11Deg. nose down and calculate
that total takeoff-moment. Then lastly, put all the tail weight back on and continue adding until you have 7 Deg. nose down and calculate that total takeoff-moment.
After you fill out the table below before each flight, the total takeoff moment ...
MUST FALL BETWEEN THE 7 DEG. AND THE 11 DEG. HANGING MOMENTS WHEN YOU WAS IN THE FRONT SEAT
View attachment 1159979

That was my initial thought as well, but I figured there had to be a formula out there that could calculate the hang angle (sin/cos) based on the distance/weight/CG/arm/etc... I'll be quite surprised if there isn't.

 

[GyroChuck]

Found this from the old forum. Not sure if this is what you are looking for.

 

[Gyro-nut]

Thank you Chuck, but my PC apparently can't run the file.
I unzipped the file, but it's not compatible with my version of windows I guess

 

[GyroChuck]

Thank you Chuck, but my PC apparently can't run the file.
I unzipped the file, but it's not compatible with my version of windows I guess

That was the wrong file. This is a zipped excel file. Hopefully this one will work. By the way how is Dan doing on my engine.

 

[Gyro-nut]

We are doing well on the engine. Last weekend we got the connecting rods, pistons, and heads all put together.
We may need to make a new engine mount, but we'll know more once we get the accessories put on.

 

[Gyro-nut]

Chuck, the second file was good to verify my original calculation (CG was within 1/4" based on my original calculation), but it doesn't help me figure out the limits of the CG fore and aft with the angle being 7-11 degrees nose down.
The angle used on this spreadsheet is assisting to calculate the vertical CG only. I don't see a way based on this info to determine the limits.
Thank you for the sheet though; it did validate my previous hang test