Ok I am building the four star 60 and have run across a question. I am getting ready to place my engine on the firewall following the vertical and horizontal thrust lines. Problem is when I center the engine both thrust lines the throttle arm sits above the firewall. So my question is, is it ok to lower the horizontal thrust line to fit the engine on the firewall and keep the vertical thrust line centered. Or do I need a smaller engine? Thanks.

lucius

Umm, that seems a bit odd. What engine are you using? I wouldn't alter the thrustline if you can avoid it. Gotta be some other way to deal with throttle linkage issues. Can you post a pic?

-Rep

here are the pictures with the mounts centered on the lines. This is my first build so I just want to make sure. I am using ys .91

thanks

first picture is fully open and the second is fully closed.

Here's a good way to deal with alignment problems and also the way throttle on 4strokes is too close to the firewall.
I use extra servo arms as these bellcranks.

Rotate the throttle arm so the travel forward and back is even, then bend a wire as in the image below

Lucious- I may be way off on this, but studying your pic & comparing to my 4star & plans, your mount looks about a half inch higher than mine. (assuming you're using the stock sig mount of course) Are you sure you have the topside of the mounting beams lined up w/ horizontal line & not the bottom? I'm showing the top of the mount should be about at the red arrow in pic.

Here's my 4Star60 with a Saito 91 mounted. The mount is a Hayes AL60. That same mount has been used to mount an OS 61 FX, OS91 FX, Super Tiger G90 and a YS110. The mount location is consistent with the thrust line. Yea, pulled the cowl cheeks off so that it would be easier to use the plane as an engine mule.

The only issue with the different engines has been the throttle control. Iuse 2-56 wire thru some sort of tube. No problems. In some cases the throttle carb arm needed to be rotated or the carb mounted in reverse of "as delivered" - swapping the high speed throttle from the left to right or right to left - what ever was needed to be able to safely access the tuning adjustments when the prop was turning.

I am not sure if I am using the top or the bottom. Is there a way to tell shich is which because they it looks symmetrical to me. <div class="vsc" pved="0CD8QkgowAQ" sig="PHJ"><h3 class="r"></h3></div>

I think your crankshaft center will line up with the upper edge of the engine mounting beams and not with the center of the engine mount.

Yes, i believe the mounts are symmetrical so it doesn't really matter which way you mount them. Just make sure that the surface facing upward, (the surface that the engine sits on) is lined up on the horizontal line. Check out your F-1 cross-section on the plans.


-Rep

If you mount your engine upright, on top of the rail (red arrow orientation), then the mount should be aligned so that the raised bit pointed to by the red horizontal arrow should be aligned with the firewall "center line". If you mount the engine inverted, on bottom side of the rail (yellow orientation), then the mount should be aligned so that the raised bit pointed to by the yellow horizontal line should be aligned with the firewall "center line".

Yea, yea - clear as mud.

Thanks SeamusG:

I think that is where I was going wrong. I was thinking I was supposed to mount the mounts the the horiz line in the middle of the two raised lines. Thanks for your help.

Lucius - the center of the crank shaft of both 2 &amp; 4 stroke glow engines is at the bottom surface of the crankcase mount. You're just trying to align the crank with the thrust link. Mounting the engine with the crankshaft aligned a little below or above won't affect the flight characteristics. But ya gotta make it look GOOD!