Tired Old Man
Posts: 11571
Joined: 2/25/2002
From: Central, CA, USA
Status: offline
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I don't want to argue the point. I agree that a lot of people seem to need to have a thrust angle built into a plane for them to be able to fly better. The problem with that is now you have a plane that to be trimmed as well as possible requires that a lot of extra input is required to offset the built in angles. That can leave you with a plane that cannot be trimed out adequately in the opposite direction when the transimitter runs out of trim availability.
There are also a lot of people that prefer a zero-zero airframe to make it more predictable and easier to trim for various attitudes and power settings. If you check around the group that always seems to be bring home the bacon at contests you just might find that a lot of them start with a zero-zero airplane and adjust the trim settings at the transmitter over many flights to get them the way they need to be. The thrust angles that are built into many of todays arf are a compromise. Then again, if you received an Edge without any thrust angle at all then there was a minor error in the positioning of a part in a jig. No biggie since a good flyer or a good builder will adjust thrust angles to suit their particular needs with any plane they assemble or build.
Personally, I'd prefer that every plane was built with a zero-zero thrust angle, but I suppose that up to 1 degree down and 1-1/2 degree right would help a few people out. I don't think that should be for everyone but people get upset if they don't have it.
As for "soft" firewalls, unless you use a composite or metal for a firewall any type of wood will eventually compress under the pressure of small radius post mounts. Some woods will clearly compress more or less than others. Woods that compress the least over a period of time are also a lot heavier than what's currently used in most arfs on the market. Spreading the pressure loads of post type motor mounts with a large fender washer under the post is an easy and smart way to avoid wood compression for a longer period of time. Adding a coat of thinned epoxy prior to mounting an engine makes the wood last even longer. Using a heat gun to help thinned epoxy soak into the firewall makes it even harder.
We get a little too wrapped up in requiring a perfect appearance for a mounted engine that's generally hidden inside a cowl and forget that there are factors other than winning an internal beauty contest that are also important. It also ends up costing people a lot more money to assemble their planes by having to buy special length, color anodized motor mounts when a simple wood block drilled for the hole spacing would actually be a lot lighter, reduce airframe vibration, reduce firewall compression, are cheaper, lighter, and generally already availible in the shops of the airplane owner.
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If you can''''t fix it with a hammer, you have an electrical problem.
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All Forums >> RC Airplanes >> Giant Scale Aircraft - 3D & Aerobatic >> WildHare R/C Support >> RE: 50cc Edge V2 has landed 
RE: 50cc Edge V2 has landed - 
My Edge had zero offset in the firewall. I ended up pulling the old firewall out and moved the new one to the end of the motor box to help shorten the standoffs. I put 1/4" RH thrust in it. Looking at the prop...the side of the box on the right is 1/4" longer than the one on the left. After that I ended up shimming 1 
