What did you do on your airplane project today?

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Kyle Boatright

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Installed the other entry/exit step. Re-bled the brakes (I think my brake bleeding system was entrapping tiny air bubbles which became bigger bubbles - hopefully I'm past that.) Installed some interior panels. Fired up the main bus for the first time. Disassembled, diagnosed, and fixed a problem with the left door latch. Finished installing the door latch warning system. Installed the wingwalks. Cleaned up some wiring. Realized I'd mis-wired the flap switch. Found the appropriate diagram and will fix it tomorrow evening.

I continue to smell fuel in the cabin, but can't find the leak if there is one. There are no obvious pools, drips, or blue stains, so I've been wiping all of the fittings and lines with white paper towels to see if I get a blue transfer from any of them. Nope. But the fuel smell lingers. I'm open to suggestions.
 
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Mark Z

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We struggled getting the rigging right in our -12s. Many of the Vans builders (who built a straight airplane) were successful tweaking the trailing edges of their airplanes. Good luck. 👍
 

Toobuilder

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Agreed about the vent. RVs are known for a fuel smell with certain flight attitudes and tank fill configurations. Maybe plug the vent, pop the caps, and see if the cockpit smell goes away after a few days.
 

Kyle Boatright

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I don’t know anything about the -10’s fuel system, but the smell of fuel in the cockpit plus no leaks, makes me wonder about the vent system.


BJC

On the -10, the vent is a line that starts at the top of the outboard end of the tank, runs inboard, then simply has a turn-down that exits through the bottom of the wing root fairing. It never enters the cabin proper, nor does it have any sort of a P-trap. But I'll recheck it and everything else tomorrow evening. Maybe its just a lingering smell from the couple of ounces of fuel that leaked inside the fuselage the first time I added fuel. We'll see.
 

J.L. Frusha

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I went back to the original patent drawings and started over, after scaling the drawings to a true-scale JN-4D.

The battle begins again...
 

Toobuilder

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Flew the Rocket today with the new rig. Still has a heavy right wing but when the ailerons are held in the centered position (TE of flaps and tips lined up with aileron), its straight as an arrow - no roll. Let go of the stick however, and the ailerons quickly snap to about 1/2 inch into a right roll. Since the mechanical and positional rig is spot on, there must be an asymetric aerodynamic load driving the ailerons. The new aileron has not had the folded TE bent/squeezed any beyond the initial bench assembly, so I think thats next. I hope that does it, because I really do not want to add a tab or wedge.

Kind of a timely problem to have for me... My employer has elected to send me all the way to Mojave to attend National Test Pilot School for their "Introduction into Fixed Wing Stability" short course, and today was day one. Maybe I can make a class project out of it!
 
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Victor Bravo

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there must be an asymetric aerodynamic load driving the aiilerons.

Right roll would be the opposite of what you'd instinctively expect for a "prop outflow swirl" to be pushing down on an ailerton, but on your airplane the prop diameter is a fair percentage of the span, so the swirl bouncing off of something and creating a counterintuitive effect is not out of the question IMHO.

Swirl creating some wierd spanwise flow at the trailing edge and "sucking" one aileron upwards?

Is this problem occurring to the same level at all alphas and airspeeds?

Downward half of prop swirl at mid-span of starboard wing, where that downward component is adding energy to another entrained vortex slightly outboard, and the "up" part of that secondary vortex further outboard is sucking the right aileron upward??? (this is reaching pretty far into the bizarre...)
 
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Tiger Tim

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The RagWing RW9 is closer, though that engine mount sure looks high.
The RW9 looks to carry its engine quite a bit higher to me, but in any case fabricating a mount that holds the engine a couple inches lower is a lot easier than starting from zero on a whole airplane design.
 

J.L. Frusha

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Do you really want it to be structurally closer, especially if you're aiming at Part 103? We've learned a thing or two since the twenties.

A ladder truss frame is a ladder truss frame. The shape of the frame determines the shape of the aircraft.

Can I change the structural design and still maintain the shape? Possibly. However, doing so may not make for a lighter airframe.

A large part of the struggle is weight and balance. First, I have to eliminate the rear cockpit of the Jenny and move the fuselage forward to meet part of the weight change.

Stick and fabric I can do and do light. I know that. I can make simple steel connectors, fashioned after the original JN-4 design. Wings can use reinforced foam ribs - not a problem.

The strut system of the S-2 'wireless' Speed Scout, plus a couple of mono-struts to make the 2-bay wing structure is easy enough. (No miles of wire and turnbuckles to fight with, either.

I can jig-up the bottom longerons while 'wet' with preservative, pre-shaping them in the necessary curve. Standard operating procedure. They can dry while I build the wings, vertical and horizontal stabilizers, rudder and elevator. No big deal.

The hard part of the weight and balance is extending the firewall-forward, to put the CG where it needs to be, to counter balance the fat guy and the rest of the structure.
 

J.L. Frusha

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OK, I admit self-doubt, which created the urgent feeling of needing a redesign of the structure.

I can do this and may have to extend the nose a tad, without screwing up the rest, to get the weight and balance exactly where I want it.

I'm a picky [email protected]$%@%# and a perfectionist. "It HAS to be 'right' from the git-go."

Build and adjust I can do.

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J.L. Frusha

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Hot ****! I figured it out!

Shortening the fuselage 94 inches, as called for, removes almost as much weight aft of the CG as dropping 400 lbs. of engine and coolant from the front.

I was overlooking the obvious.
 

Pops

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Flew the Rocket today with the new rig. Still has a heavy right wing but when the ailerons are held in the centered position (TE of flaps and tips lined up with aileron), its straight as an arrow - no roll. Let go of the stick however, and the ailerons quickly snap to about 1/2 inch into a right roll. Since the mechanical and positional rig is spot on, there must be an asymetric aerodynamic load driving the ailerons. The new aileron has not had the folded TE bent/squeezed any beyond the initial bench assembly, so I think thats next. I hope that does it, because I really do not want to add a tab or wedge.

Kind of a timely problem to have for me... My employer has elected to send me all the way to Mojave to attend National Test Pilot School for their "Introduction into Fixed Wing Stability" short course, and today was day one. Maybe I can make a class project out of it!

On the Falconar F-12 I had to have a small trim tab on a aileron for a heavy wing. Double checked and found a flap that was not perfect. Built a new flap and that took about 1/2 of the heaviness away. Re- adjusted the tab. Then a few years latter I decided to add gap seals. On the test flight after installing, the other wing was heavy. Removed the trim tab and everything was OK. Maybe the airflow thru the aileron gaps were different. I don't know.
 
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