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Tantrum1

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SO we pulled the trigger on a new shop tool a couple weeks ago. We purchased a Sienci Labs 30 X 30 Longmill CNC router kit. Its arrived, but I haven't had a chance to assemble it yet but hoping to start assembly this weekend coming. the plan is to use it to build the remaining molds for the smaller parts that I will be needing soon. I was able to justify it, cause I've been outsourcing my cnc work to a local cabinet maker with a 5 X 10 machine, but I was supplying the files and the material and then paying his shop rate. So with the quote I got for the next 3 parts I need to have done, it pretty much has paid for itself. I will end up doing other stuff also. Might try to turn it into a little side hussle to help support my airplane building affliction! I will post pics, once its up and running.
 

Jay Kempf

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You will love your new toy. Have been running mine pretty hard lately doing composite tooling. Always more to learn. But easy to be productive after a little deep dive into Mach3/4 and how to run steppers. Look into Fusion360 for tool paths. Very nice and the Edu version is free for now.
 

Tantrum1

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So here's a pic of one of my first attempts at a custom monogramed head rest for my racer. Didn't turn out he way I wanted it to however I learned a lot! My next attempt will be better! I'm loving my LongMill!
 

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BJC

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Looks like fun. Wrt floorboards and headrests, what is your projected empty weight?


BJC
 

Tantrum1

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BJC,

Minimum empty weight for Formula 1 is 500 lbs. Realistically for me, I won't be all that close to that, cause theres no way I can justify to my wife that I'm building an aircraft to only fly 1 week a year hahahaha. As it sits right now on the gear, engine, fuselage, tail, fuel/oil system and wings it comes in at 460 lbs. So realistically my target weight is 550lbs empty. the floor boards are thin and of varying thickness. The floor boards under my feet are 2ply carbon and are just to give my heels something to rest on when flying and the the floor board under the seat is reinforced with 1/16" plywood. and the floor board in between the 2 is 3 layers of 2X2 twill and 1 ply of biaxial carbon. They work pretty good. I will weight them and post the total weight of floor boards as soon as I get a chance.
 

BJC

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Thanks:

I was curious about whether or not you were shooting for 500 Lbs.

You can remove stuff when you go racing.


BJC
 

Victor Bravo

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That extra 50 pounds over minimum weight could well be the difference between finishing first and fifth. 50 pounds in a 2.5G turn is 125 pounds of "weight", and if the L/D of the airplane in that turn is 5 to 1 then you are making 25 pounds more drag than an identical airplane that weighs 50 pounds less. Some of our brighter guys here can figure out how many horsepower it takes to overcome 25 pounds of drag at 250 MPH... I'm guessing 3 or 4.

As a data point, I remember that Jon Sharp removed all of the instruments from his panel except for the oil temperature when he raced Aero Magic and Nemesis. Oil temp was the one thing that would allow him to estimate several different factors (oil quantity, oil pressure, oil flow, cooling system, CHT, etc.) that would serve as justification for pulling off of the race course. His reasoning for this was that the weight of the other three or five instruments, a few pounds of gauges, was causing him to lose half a horsepower or something.
 

pictsidhe

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25lbs of drag at 250mph and 75% efficient prop is 25hp. That is significant. Make that fat removeable!

Alternate panels seems a good idea to me.
A blinking red light set to go off with multiple different errors would be lightest.
 
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rv7charlie

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25lbs of drag at 250mph and 75% efficient prop is 25hp. That is significant. Make that fat removeable!

Alternate panels seems a good idea to me.
A blinking red light set to go off with multiple different errors would be lightest.
Whoa; you guys are not trying to say that 25 lbs of weight is 25 lbs of drag, are you? (That ain't so...)
 

Victor Bravo

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Whoa; you guys are not trying to say that 25 lbs of weight is 25 lbs of drag, are you? (That ain't so...)

I ain't got the engineering chops to do it accurately, but remember my example was in a 2.5G racing turn (which is slightly more than 50% of the time), and a wild guess at the airplane's achieved L/D during that turn. In level 1G flight, a 12 to 1 L/D aircraft would generate (added) drag equivalent to 1/12th of that 50 pounds of extra weight.
 

pictsidhe

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For
e=0.9,
b=20ft
g=2.5
V=250mph
STP

Induced drag is 2lb higher if gross increases from 700 to 750lb: 2hp
Induced drag is proportional to the square of load, so higher gs see a heavier penalty. Parasitic drag will also increase a bit.
At speeds well above best glide, increasing weight will increase the L/D, even though drag increases. There will probably be slightly more parasitic drag, but less than the proportion of weight increase. That isn't so easy to estimate. Using the base airfoil L/D, maybe around 50, might be in the ballpark. So , total drag increase, 3lb for an equivalent power of 3hp.
 
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Tantrum1

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Hey guys, thanks for all your comments! Believe me when I say "I have thought and considered all of what you mentioned" the entire time i've been building this. 550lbs is my target weight for finished airplane in "sport flying trim". I'm not a wealthy man and am building on a budget (some of which has been over budget) and I don't own another aircraft. So I am building this to be able to race in the gold division of Formula 1 but also be able to fly it locally to fly-ins, and such. So some concessions needed to be made. However once its finished and flying, there are definitely places in the aircraft that could shed some weight for race week.
However all this being said my biggest weight reduction for race week is going to be myself. I've been working hard to drop some weight, At the beginning of this Covid crap I was 198 lbs, I'm down to 187, and am aim for the 165-170lb mark. So that in itself will help make a difference.
Thanks for all the advice, it doesn't go unnoticed!
Mark
 

Riggerrob

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Congrats!
The ideal EAA Chapter includes a welder, an electrician, a painter, a CNC specialist, etc. who share their expertise to help complete each others' airplanes.
You are also correct about the profitability of a side-gig CNCing parts for hot-rodders, antique airplanes, antique cars, antique boats, etc.
I have used my 3D printer to make replacement buttons, a replacement drawer kitchen drawer slide, a guitar piece, etc. long after originals were out of production.
 
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