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Building Tips and technical articles. => Building techniques => Topic started by: Ty Marcucci on July 07, 2013, 01:57:57 PM

Title: How to make an intake in a cowl.
Post by: Ty Marcucci on July 07, 2013, 01:57:57 PM
This is for my Volunteer.
Title: Re: How to make an intake in a cowl.
Post by: Allan Perret on July 08, 2013, 07:32:30 AM
This is for my Volunteer.
So how did you install the ply ring, and what is thickness of ply ?
Title: Re: How to make an intake in a cowl.
Post by: Allan Perret on July 08, 2013, 04:07:43 PM
The 1/64th ply ring was a lazer cut item in the Volunteer kit. I placed it according to the plans. I used fast setting  super glue to apply it, glued my finger as well, fun.
This "idea" of the ply ring comes from two sources that I know of, Bob Hunt and Walter Umland. I have used it before and it made making the inlet hole much easier and truer, er, accurate.. Not sure "truer" is even a word. LL~Did spell check and it is a word.
OK, this is what I don't understand.  The ply ring is glued onto the flat face of the cowl block.  When you sand in the normal contour won't you end up sanding all the way thru the ply ?
Title: Re: How to make an intake in a cowl.
Post by: GregArdill on July 15, 2013, 05:07:04 PM
Can you tell me why your air intake is that big?

By most cowl theories I've heard you need to have the outlet 2-3 times larger than the intake to get good airflow over the engine.

With an intake that big you could actually have the air coming back out of it.

Greg
Title: Re: How to make an intake in a cowl.
Post by: GregArdill on July 17, 2013, 01:20:04 AM
Hi Greg. Well, it's in the kit, the original has it that large and it works. I'm not going to question Jim Lynch nor  his designs.  D>K


I generally respect anyone who designs a successful model, but I've heard of instances where the design, doesn't translate in to an accurate representation by the kit manufacturer.

Does the original have such a large inlet?

If so and it works I'm happy to leave it at that.

Greg
Title: Re: How to make an intake in a cowl.
Post by: john e. holliday on July 17, 2013, 08:11:59 AM
Yes, some designers did have large intakes on their cowls.  What was not shown most times was the exit portions of the cowls.   Ask Dave Trible if he remembers the one he spent time on just to have it explode while doing first flight of plane.   Plane sped up about 5 mph once that happened. 
Title: Re: How to make an intake in a cowl.
Post by: builditright on July 17, 2013, 09:57:46 AM
I generally respect anyone who designs a successful model, but I've heard of instances where the design, doesn't translate in to an accurate representation by the kit manufacturer.

Does the original have such a large inlet?

If so and it works I'm happy to leave it at that.

Greg


Hi Greg,

 in the past that generally was the case with many kits however, with the kits I make I try to reproduce each kit as close to exact as it was designed
externally and make any/all mods only to the inside of the model for better/modern construction methods.

One of the great things about my Volunteer kit is the designer (Jim Lynch) was involved from the conception of the kit on to building
the kit prototype.