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140% ft edge build thread!

The Hangar

Well-known member
#1
Alrighty guys, I’m actually doing it! Although I do want to build a true “monster edge” with a monster radial and such, I’m going to be starting with a 140% edge. I’ll be using two 9g servos in each control surface, and I’ll be using a rimfire .15 electric motor with a 12x6 prop. I’ll be doubling up the tail feathers and making a bevel on either side and using the two paper layers touching each other as a hinge. I don’t plan on adding landing gear to keep the weight down.

Here are the plans blown up to 140%
 

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The Hangar

Well-known member
#8
I think so. If you compare the P 47. Its got a wide and long cowl out front. Mine has plenty of giddy up
Ok, thanks! The stock edge has a 6 inch cowl and I was able to fly it with a 9x5 on 3s fine. When you do the math, there is 3.5 inches of exposed prop vs 3 inches of exposed prop, but to get the same ratio I’d have to have 4.2 inches of exposed prop on the big one. (Sorry if that didn’t make sense - I didn’t explain it well...) I could probably push it to a 13 inch prop if I wanted, but on the site it’s only rated up to a 11x7... With a 12x6 the motor is barely warm to the touch after a 15 minute flight with quite a bit of full throttle.
 

Figure9

Well-known member
#9
Ok, thanks! The stock edge has a 6 inch cowl and I was able to fly it with a 9x5 on 3s fine. When you do the math, there is 3.5 inches of exposed prop vs 3 inches of exposed prop, but to get the same ratio I’d have to have 4.2 inches of exposed prop on the big one. (Sorry if that didn’t make sense - I didn’t explain it well...) I could probably push it to a 13 inch prop if I wanted, but on the site it’s only rated up to a 11x7... With a 12x6 the motor is barely warm to the touch after a 15 minute flight with quite a bit of full throttle.
I suspect the highest efficiency from a prop is produced toward the outside portion anyway. Years ago a Gee Bee Model Z Racer replica was built at Flabob. I often wondered how the heck it could fly since it seemed most of the prop was blocked by the cowling over the Wasp Jr.
 

BATTLEAXE

Well-known member
#10
I suspect the highest efficiency from a prop is produced toward the outside portion anyway. Years ago a Gee Bee Model Z Racer replica was built at Flabob. I often wondered how the heck it could fly since it seemed most of the prop was blocked by the cowling over the Wasp Jr.
Looks at any Rare Bear and you will se that it has a fat fuse and a small prop, less then half the prop washes out past the fuse. And it's a fast plane. Plus it will be the ESC that limits you before the motor does, that rimfire, if you read the manual, will say it is rated up to a 18" slow-fly prop
 

The Hangar

Well-known member
#12
So the more I think about it, I won't be able to pull this off within the next 9 days of build-ruary, so I'm gonna set it aside for the next week and a half then finish this thing up!
 

The Hangar

Well-known member
#13
So the more I think about it, I won't be able to pull this off within the next 9 days of build-ruary, so I'm gonna set it aside for the next week and a half then finish this thing up!
Plus I just don't feel like cutting out another edge - I just cut out most of a standard edge earlier this week and it is intense... :LOL::p