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Building Tips and technical articles. => Building techniques => Topic started by: Ken Culbertson on March 04, 2018, 04:06:26 PM

Title: OS46FX Profile
Post by: Ken Culbertson on March 04, 2018, 04:06:26 PM
I am building a profile testbed to get things right before building a real airplane and I have a question on component weights.  This beast will be powered by an OS46FX which is HEAVY but powerful.  I am not the scientific type so I need some help answering a weight distribution question.  By nature I build light.  My .35 size planes were always under 40oz.  Now I am in a totally different world and I don't know what things should weigh. 
I don't like adding weight to get the CG right although it is almost always necessary. 

The finished stab weighs in at 80 grams unfinished.  I plan to use Monocoat so the finish will not be too heavy.  Is this heavy for a stab on a plane this size (620 sq")?  Is it better to add strength to the tail and fuselage knowing that I have a 14 oz of lead in the nose already.
Title: Re: OS46FX Profile
Post by: john e. holliday on March 04, 2018, 05:18:28 PM
Sit down and start reading through the posts of the build threads on this forum.   Yes it will take time and as for me a couple of pots of coffee to read them. VD~
Title: Re: OS46FX Profile
Post by: Ken Culbertson on March 04, 2018, 06:58:21 PM
Sit down and start reading through the posts of the build threads on this forum.   Yes it will take time and as for me a couple of pots of coffee to read them. VD~

Been there, done that, ran out of coffee.  That is why I posed the question.  Very few people use the FX.  Most everything I found was for the LA and absolutely nothing on the  concept of intentionally building a heavy rear end instead of adding tail weight.
Title: Re: OS46FX Profile
Post by: john e. holliday on March 04, 2018, 07:56:48 PM
Well one way is to move the engine back on the mounts.  Granted you may have to cut into the leading edge of the wing for a fuel tank.   D>K

Also adding a longer fuselage for the tail surfaces shouldn't hurt that much.   In fact it will give the elevator more power to maneuver. D>K
Title: Re: OS46FX Profile
Post by: Roger Vizioli on March 05, 2018, 09:53:39 AM
Well one way is to move the engine back on the mounts.  Granted you may have to cut into the leading edge of the wing for a fuel tank.   D>K

Also adding a longer fuselage for the tail surfaces shouldn't hurt that much.   In fact it will give the elevator more power to maneuver. D>K

John, Ken.
When faced with cutting in to leading edge for tank space on a few profiles, I have mounted the tank on the inboard side of the fuselage to eliminate weakening the LE. Have flown most of the pattern with this configuration , no fuel feed problems. Comments anyone?
Roger V.
Title: Re: OS46FX Profile
Post by: Dane Martin on March 05, 2018, 10:12:10 AM
I run nearly all my profiles with the tank inboard.