Badan Vertigo 2M Build Thread!!

[Cosmith]

At the top I did a 6mm overlap so that the cowl completely covered overtop of F2. Then the hatch butted up against and was flush with the cowl.

Just a tip though in terms of build sequence...
* The fuse is built... so next build the hatch and get the fuse and hatch sanded nice
* then mount your motor where it should go.
* mount your cowl ring
* finally... fit the cowl so that it centers on the motor shaft, overlaps the fuse sides / bottom and comes out perfectly flush with the hatch and butts up to it (which also means the cowl overlaps F2 completely).

The cowl should be the last thing to be done. You may have to trim the TE of the cowl to make all this work. You may even have to build up the cowl ring a bit as required. The cowl is simply a cosmetic shroud and the hatch/fuse/motor placement is far more important.

Thanks...I have been working on the stabs and wings at the same time, was just trying to keep myself busy while glue was drying and was anxious to get it looking like a plane. What is your method for mounting the motor/engine in terms of getting the output centered?

[tbrum]

Here are a few pictures to show the cowl just overlapping F2 and butting up flush against the hatch.

There are more pictures in post #353-357

[tbrum]

Thanks...I have been working on the stabs and wings at the same time, was just trying to keep myself busy while glue was drying and was anxious to get it looking like a plane. What is your method for mounting the motor/engine in terms of getting the output centered?

WARNING... the post below contains ugly trigonometry. Many slept or drank through this in highschool/university/college, so please skip if this makes you sick

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Cory.... I have some pictures of the motor mounting in post #105/106, however I'll summarize...

1) Find the center of the firewall, F1, make crosshairs at center
2) Since there is no vertical trust angle, your motor will be mounted on the vertical centerline
3) Measure how much angle is in the firewall... I beleive it was 2deg, but please check.
4) Slip the cowl on and measure length of motor + standoff to get to spinner backplate.
5) Use Trigonometry with this length and angle of firewall to figure out the offset required from the horizontal centerline.
6) Install motor.


Trigonometry... Soh-Cah-Toh.

Use the Soh... Sin(firewall angle) = (offset distance) / (distance from spinner backplate to firewall)

Solve for offset distance.... offset distance = (distance from spinner backplate to firewall) x sin(firewall angle)

Plug in the 2 variables in your calculator and this will tell you the offset from the centerline of the firewall to mount your motor/standoff.

[tbrum]

An example helps... here's assuming a 2deg thrust angle and a 7.5" length of motor and standoff.

Excuse my scribbling... just something rough....

[akabek]

Cory, another option you can try is to first mount the engine. Place some tape in 3-4 positions around the fuselage so you mark off reference points where the cowl ends on the fuselage. Take the cowl off and measure the distance between where the ring is mounted on the firewall and the marks on the tape. Using those measurements tack the ring to the canopy with 2-3 dabs of CA. Then test fit the cowl. When you have it right you can hysol it in. If you need to adjust the ring it does not take much to brake the small CA joints.

[tkbig]

Well, I don't think I slept through trig in high school but it was definitely relegated to the "what the H*** will I ever use this for and relegated to the forgotten file. LOL

My low tech method is to mark the off set angle on a piece of paper using a protractor. Extend the lines as required for the distance from the back plate to the firewall and then just measure the distance between the lines at that point. Probably not as accurate as Trevor's method but seems to work for me. I just get a headache now at the mention of "sine", "cosine" etc.

[Pschulte]

Great explanation for figuring out the offset.

[tbrum]

I just get a headache now at the mention of "sine", "cosine" etc.

LOL. I get those headaches also. Had a persistent headache for 5-years in University but now I know why.. I got one drawing up my example

Thanks for describing your way of drawing out the solution

[Cosmith]

Hey guys, this place is awesome!

I just did Terry's drawing method...I'm getting a 6mm offset using 2 degree angle at 17mm from firewall to back of spinner. Is this in the ballpark of your measurements Trevor? Does 6mm sound reasonable?

Thanks again!

[tbrum]

Sure does!!!