Yes, heard of it. Never paid any real attention to it though.
Ran the engine on the old RV-3 without wings -- even with prop. Yes, it'll wobble on the gear legs and tires, but I really don't see how the wings would make a difference. in fact, with wings you'll have more momentum, putting more stress on the fuselage forward of main wing spars to the firewall as opposed to having all of the fuselage turn freely.

Is the idea that the inertia of the tail and rear of the fuselage could introduce twist in the fuselage that otherwise would somewhat be absorbed by the wings and limited to forward of the main wing spar?

Finn

On 5/25/2020 4:43 PM, Charlie England ceengland7@gmail.com wrote:

Forgot to mention this...

I suppose you've heard the RV lore about twisting the fuselage by running without the wings attached. No one that's complained about it has documented all conditions when it supposedly happened, but I wonder if they had the tail on and no wings. In any case, I can't imagine it being an issue when running without a prop.

Charlie

On 5/25/2020 3:38 PM, Charlie England ceengland7@gmail.com wrote:

If the regulator has a MAP port and it's connected to the intake, then fuel pressure should vary with MAP. That's supposed to keep fuel flow proportional to airflow. But MAP is absolute; fuel pressure measurement will depend on the type of sensor (relative to atmospheric, or absolute).

I wouldn't attach any significance to bubbles in the return line; the regulator is venting (spitting) fuel through what can be a tiny slit, into the relatively free air of the return line.

Charlie

On 5/25/2020 2:57 PM, Finn Lassen finn.lassen@verizon.net wrote:

Don't have the wings on. Ran from a 6 gallon jug next to the fuselage. Can use a transparent line for the fuel return to inspect for bubbles.

How is the fuel pressure regulator supposed to work? Looks like the fuel pressure dropped a bit as MAP dropped. Is that the way it's supposed to work?

Finn

On 5/25/2020 8:59 AM, Charlie England ceengland7@gmail.com wrote:

On Sun, May 24, 2020 at 10:34 PM Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

Good point. From the log I think it was running lean. I'm temporarily using a narrow band O2 sensor. I think I'll hook a multimeter directly to it to bypass any errors from sensor to EC3 and EC3 to EM3 and its display. And I have to read the EC3 manual  :)

Those o-rings were a bad idea. If I'd had a mill and could have milled recesses to retain them from expanding out under pressure they might work. But an o-ring between two flat surfaces is probably bad design. If sucking air, won't I see that in the return line as bubbles?

You won't if you use proper fuel line. ;-) The big issue is loss of power if it starts sucking air at a critical time. I've got a couple of friends who fly big-Continental powered Globe Swifts. They've both had forced landings (one of them multiple times) before they found that the ancient flex lines feeding the fuel pump had dried out and were porous to air but not fuel. Never leaked fuel, but would intermittently suck air and cause engine stoppage.

Charlie

Finn


On 5/24/2020 10:56 PM, Charlie England ceengland7@gmail.com wrote:

Congrats on 1st run. Doubt that the issue is no prop; they idle ok in the car without one. ;-)

Don't neglect the input side; those pumps will suck air even better than fuel.

Charlie

On 5/24/2020 9:01 PM, Finn Lassen finn.lassen@verizon.net wrote:

Probably too early to give you that. (Used 8.10 and PICkit2).

Ran for the first time today (no prop).

Over speeding not an issue. Ran like a Harley :( 
No sure if because no prop or because not tuned yet or if something else wrong.

Zero RPM readout on EM3. I must have misunderstood the instructions or the program. I thought the EM3 got RPM from the EC3, so I didn't wire the tach input to the EM3.
EM3 shows "NOP" until EC3 is turned on. Then shows "0".

Only did a couple of runs. Fuel pumps started leaking badly around O-rings when I adjusted fuel pressure up to 37psi (engine not running). Pooled up in fuselage. Need to fix before I try running again. Gas is cheap, but not that cheap. I'll try copper washers on the pressure (output) side instead of the o-rings.

Yes, I know, not pretty. Threaded the output fitting at an angle :(
Too lazy to redo the output block.
I also need to bend a new input tube without a kink.

Max oil pressure only about 50 psi, hopefully because of low RPM.
Forgot to turn on master switch so alternator didn't come on-line.
Didn't log the run where that worked.

Anyhow, can now say I've run the engine :)

Finn

On 5/22/2020 6:12 AM, Stephen Izett stephen.izett@gmail.com wrote:

Great work Finn
Could I get the MPLABs version your using and any more info for the build.
I could build and program and confirm the burn but the EC3 ran like a dog.

Steve

On 22 May 2020, at 9:16 am, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

Well, after several hours of Murphy working overtime, I finally was able to get the wiring on my EC3 chip programming board right, chips programmed and EC3 installed.

Flux capacitor fluxing, injectors clicking and spark plug firing.

Time to get the wheels on and roll it out and start the engine.

Oh, wait, guess I need to finish and install the prop :(

Finn


On 5/21/2020 9:23 AM, Finn Lassen finn.lassen@verizon.net wrote:

1) Without prop any vibration will be from engine and PSRU and can inspect engine (leaks, etc.) with no fear of prop.

2) With prop less chance of over rev and some cooling air through rads and oil cooler.

What do you think?

Finn



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