REFLECTOR: Franklin engine noise?

[Hiroo Umeno]

Thanks to all that responded to my Franklin noise question.  It seems from the response I got that my engine is doing the "Normal Franklin thing".  Incidentally, I also did notice that the rpm drop on the mag-check was more than I am used to on a Lycoming (120rpm or so as opposed to 70 or so).  Since it stabilizes and continues to run, I figured it was fine but I am glad to hear that is normal.  I will check on the idle mixture.

It seems like I will need to re-set my yellow and red lines on the engine display.  Where do you guys have the yellow and red lines for the Franklin RPMs?

Hiroo


________________________________
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Michael Watson
Sent: Tuesday, March 20, 2007 11:25 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Franklin engine noise?

Hiroo,

I sent you a post on Sunday but for some reason it did not go through, so here goes.

As others have stated, the Franklin engine has a !0.5 to 1 compression ratio with a
high lift overlap cam like a dragster, which it sounds like at idle, it does not like
to idle under 950~1000 RPM. Adjust your idle stop screw for 950 RPM then adjust the
idle mixture screw to peak idle RPM which should result in an idle of close to 1000
RPM. This will prevent plug fouling at idle and taxi, but it is still recommended to lean
aggressively during taxi and hold.

If your idle is between 700 ~ 850 RPM, it will cause the canard to vibrate violently
and do nasty things to your engine mount rubbers.

Mag check drops are much higher then other aircraft engines

Climb at 26/2700 and cruse at 24/2550 ~2600 and always keep the RPM above
2450 unless landing.

Mike W.

On 3/20/07, Laurence Coen < lwcoen at hotmail.com<mailto:lwcoen at hotmail.com>> wrote:
Hiroo,

John is right, 600 RPM is too slow.  The recommended idle is in the range of 750 to 900 RPM.  The Franklin has a large valve overlap which works great at high RPM but is terrible at idle.  On engine start I have rough idle at 1000 RPM but by leaning immediately, the RPM will rise to as much as 1300 RPM and things smooth out a whole lot.  If you don't lean for ground operation you will foul your plugs.  My idle is set for 750 RPM but warm-up is 1100-1200 RPM.  750 RPM idle is still rough but 900 RPM makes things tough for short field landings.  As far as I'm concerned, landing is the only time you need to hit the idle stop.

Larry Coen
N136LC
SE/RG Franklin-IVO
----- Original Message -----
From: Hiroo Umeno<mailto:humeno at microsoft.com>
To: Velocity Aircraft Owners and Builders list<mailto:reflector at tvbf.org>
Sent: Monday, March 19, 2007 4:40 AM
Subject: REFLECTOR: Franklin engine noise?

I have a favor to ask for those who are flying a Franklin.

Would someone able to capture the engine startup, runup, and idling sound digitally?  It does not have to be "audio-phile" quality.  Some handheld device is fine but preferably with gain set low enough that it does not clip due to high sound pressure.

What I am looking for is...

Startup, running at 1000rpm, runup at 1700rpm, mag-check, then idle with throttle pulled all the way back.

I am convinced that my Franklin is "missing a beat" but I do not have any reference to compare against.

I finally got mine running again this weekend (changed the ignition harness) and it is back to its old trick of growling and shaking. The shaking is most pronounced when the throttle is pulled back all the way and the engine is idling at 600rpm or so.  You can see the canard tip bounce around ½" or so at the tip.  My wife thought that I had some bolts loose.

Hiroo


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--
Mike W
1997 Velocity Elite RG
Franklin /IVO Electric CS
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