Mounting the DA 50??
 

Hi,
I am a bit perplexed on how to acurately mount the DA 50 on the H9 CAP. The center is marked on the FW and I have measured the distance between the standoffs. Before I start drilling and cutting, how did you do this?

Thanks.

Joe ;)

RE: Mounting the DA 50??
 

Any pictures?

Joe !~)

RE: Mounting the DA 50??
 

Joe,

A couple things to consider. You want to have the center of the prop shaft exit the center of the cowling. To do this you need to know a few things. First, does the firewall have any right thrust built in. Next, how much distance is there from the firewall to the front of the cowl. If you want to have the engine mounted with some right thrust (and your firewall doesn't have any built in) you'll need to either get some standoffs with the correct angle, or you can get a few metal washers to shim the standoffs you have. Now that you know the amount of right thrust you can figure out the distance that you need to offset the rear of the engine (if you don't offset the rear of the engine the prop shaft will end up right of center). To figure out the rear offset you need to know 2 things: the overall length of the engine from firewall to the front of the drive hub (leaving a little gap between the prop and cowl), and the angle of right thrust you want. Use the tangent of the angle multiplied by the length. Tan(angle) x length. Now you can draw a reference line on the firewall. The line will be drawn on the left side of the actual center line (when viewed from the top/rear of the plane) and offset by the amount you just calculated. Now you need to draw a line perpendicular to your reference line at the thrust line. This is probably in the manual for the plane and probably measured down from the top edge of the firewall.

The rest is easy. Just measure the distance between centers of the bolt holes in your standoffs (noting the orientation that you want to mount the engine, inverted/upright, etc.). Measure off your reference lines on the firewall and draw new lines that are half the distance of the bolt centers. Do this for both the horizontal and vertical bolt spacing. The intersections of your lines will be the spot you drill for mounting bolts.

If you measured correctly, all the bolts will line up perfect and the prop will be in the center of the cowl.

Hope this is easier to understand than it was to put into words?

Ben

RE: Mounting the DA 50??
 

Here's a little offset calculator. It works very well

http://www.gsal.org/tools/offset_calc.htm



This works also:
If you can stand the plane upright and secure it, set the engine on the firewall, put the cowl on and line the shaft up with the cowl opening. Carefully remove the cowl and mark your standoff locations on the firewall.
This is sometimes easier said than done, but if you don't have the elevators and rudder on yet it is pretty easy.

RE: Mounting the DA 50??
 

Thanks guys. I have figure out the bolt spacing and made a jig of sorts. I think it will work. The right thrust and off center is already marked and I'll go with what is already there. Thanks Jemo for the standing the plane up idea. I have done that with a 40 size plane and it worked good.
I will check back and let you know how it comes out!

Joe :D

RE: Mounting the DA 50??
 

It mounted up easy! I still have to creatively slice a piece off the firewall so the pitts will fit. I'll do so glass and angle stock as I go, I can not believe the copression this thing has when I turn it over by hand. This could be fun!!

Joe !~)