Sent: Wed, 19 Sep 2007 1:16 pm=20 Subject: [FlyRotary] Re: Strange Ignition?=20 I do not believe that is a significant factor, either, Al. After = all, we're suppose to do our ignition checks on the ground before take = off {:>). My understanding is that best power on the 13B has ignition = timing between 25-28 deg BTDC, so not surprising that the 20B would fall = in that range also. Sounds reasonable to me.=20 Ed ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Wednesday, September 19, 2007 3:08 PM Subject: [FlyRotary] Re: Strange Ignition?=20 =20 I wondered if perhaps one issue was that I was doing the = ignition check static, on the ground; where the combination of RPM and = MAP would be different than in the air. But on checking with Tracy 's = spreadsheet on the timing settings, over a fairly broad range above = about 4900 the timing is (should be) in the range of 26 to 28 degrees = BTDC. Al -------------------------------------------------------------------------= - Email and AIM finally together. You've gotta check out free AOL = Mail! =20 -------------------------------------------------------------------------= --- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.487 / Virus Database: 269.13.22/1015 - Release Date: = 18/09/2007 11:53 AM ------=_NextPart_000_0011_01C7FAF4.E55E1160 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

George, if you are talking about the ignition = sequence for=20 a two rotor, there is a combustion event every 180 degrees of the e = shaft=20 rotation. So one complete cycle of a rotor face =3D 180 deg of e = shaft=20 rotation. 6 faces * 180 =3D 1080 deg e shaft rotation for all = six faces=20 to fire.

The six faces are therefore 180 deg apart = (eshaft=20 reference). IF face #1 of rotor #1 fires at 25 deg BTDC then the = next face=20 on rotor #2 will fire 180 degrees later, then 180 degrees later the face = #2 on=20 the #1 rotor will fire. Then 180 degrees later the #2 face on rotor #2 = will fire=20 etc.

So to answer your question, ALL Faces fire the = leading=20 spark plug 25Deg BTDC for their respective=20 cycle. But if you want to know where the nth face fires = relative=20 to the first face firing, the answer is the nth rotor face = fires at=20 (n-1)*180 deg + 25Deg later - where=20 n is the face number in question. Remember the = firing faces=20 will alternate from rotor to rotor.

So the second face, n=3D 2 fires at = (2-1)*180 + 25 =3D=20 205 deg (using the first face firing at 25 BTDC). The third face, = n=3D 3=20 fires at (3-1)*180 + 25 =3D 360+25 =3D 385 deg.

The sixth face n=3D 6 fires at (6-1)*180 + 25 = =3D 925 deg and=20 if we go back to that first face, we have n =3D1 so (1-1)*180+ 25 =3D = (0)*180 + 25 =3D=20 25 Deg BTDC or back where we started. This is just for the leading = plug,=20 but you can do it for the trailing plug.

So if the 1st face TDC point is used as a=20 reference and was on the number one rotor, then the 2nd face to=20 fire will be on the number two rotor. So number one rotor = will fire n=20 =3D 1,3,5 and rotor number two will fire 2, 4, 6. (even and odds = alternating of=20 course)

Number one rotor will have firing events at 25, = 385 and=20 745 degs, number two rotor will have firing events at 205, 565 and 925 = degrees=20 of e shaft rotation.

That is if I have not screwed things up = somewhere along=20 the line

Ed.

----- Original Message ----- =

From:=20 George=20 Lendich
To: Rotary motors in = aircraft

Sent: Wednesday, September 19, = 2007 6:30=20 PM

Subject: [FlyRotary] Re: = TDC

Can someone answer this questions, = if the=20 timing is set at 25 degrees BTDC and the leading fires at 25 degrees = BTDC=20 and the Trailing fires 15 degrees later (10 degrees BTDC) - when = does the=20 third spark event fire, is that another 15 degrees with the = leading=20 firing again?

The pulley end keyway points = to 9.00 at=20 TDC ( plug sides) on the housing closest to the pulleys ( = Front/=20 our rear) - is this what is referred to as No1 housing?

George (down = under)

<snip>

In a message dated 04/26/2005 12:00 Central Daylight Time, = Lehanover=20 writes:

<< In a message dated 04/25/2005 07:00 Central Daylight = Time, jwvoto@itlnet.net writes:

I can look into the spark plug hole and see the apex seal go by, = so are=20 you calling apex seal crossing leading plug TDC?

There are a number of gags to locate TDC close enough to get the = engine=20 to run.

(1)

Remove one spark plug from number one housing. Screw a length of = hose=20 into the plug hole. Put your tongue on the end of the hose. Gently = turn over=20 the engine. When you get a null, where there is no pressure and no = suction=20 on your tongue, that's TDC. Good to within a few degrees.

(2)

Or,

Bend up a piece of welding filler rod so as to make a pointer = that can=20 touch a flywheel (flexplate) tooth. Bolt or clamp the wire to the = rear=20 iron.

Take both plugs out of number two rotor housing.

Turn the engine until you see an apex seal in the center of the = trailing=20 plug hole.

Bend the filler rod so that it points to the center of a flywheel = tooth.=20 Put a white paint drop on that tooth.

Turn the engine in the running direction, until that same apex = seal=20 appears in the center of the leading plug hole.

Put a paint drop on the tooth the rod is now pointing at.

Count the teeth between the paint dots. Divide by 2.

The point half way between the two paint dots is TDC in the = number one=20 housing.

Good to within a few degrees.

Also, you can count the total number of teeth and divide that = number into=20 360 to get the number of degrees per tooth. Paint the correct tooth = yellow=20 and make the rod a permanent piece, for setting accurate timing in = an easy=20 to see location.

(3)

Or,

(Similar to above)

Take both plugs out of number one.

Turn engine in running direction until an apex seal appears in = the=20 trailing plug hole.

Gently turn the engine backwards until an apex seal appears in = the=20 leading plug hole.

Half way between those two events is TDC. With practice, accurate = enough=20 to do by just feel and rocking back and forth by hand and to find = TDC within=20 a few degrees, or close enough to drop in the distributor and have = the=20 engine fire instantly and run fine.

(4)

If you used grease or Vaseline on the side seals, you can have a = plug=20 prepared with the center knocked out of it and a plug in place with = a piece=20 of brake line soldered through the center. Screw this special plug = into the=20 bottom plug hole. Push a length of plastic tubing over the piece of = brake=20 tubing. Pour auto trans fluid through the top plug hole. Reinstall = the top=20 plug. Hold the hose in the vertical. Turn the engine until the fluid = level=20 nulls.

That's TDC number one with a degree.

(5)

The flywheel end counter weight is centered between the plugs on = number=20 two rotor housing. That's TDC number one within about 10 degrees. = But you=20 can get good at it, and get more accurate.

(6)

If you have the front pulley bolt and washer off, looking from = the front=20

pulley end,

the keyway in the 9:00 O'clock position is TDC number one within = a few=20

degrees.

My TDC rig is for setting up port timings and requires a = disassembled=20

engine, so that won't help you. Good for inside of one degree. =

(6)

Quick and dirty.

Take out either plug from number one housing.

Wet a finger. Hold it gently over the empty plug hole. Turn the = engine in=20

the running direction. When the air quits pushing past your = finger,=20 that's TDC

within 10 degrees or less.

Lynn E. Hanover

<snip>

On 9/19/07, bmears9413@aol.com <bmears9413@aol.com> = wrote:=20
Changing=20 the subject a bit, I want to make sure i have my motor on TDC to = set my=20 timing marks on the flywheel. This is my plan, tell me what you = think. I'm=20 building a fitting to screw in the spark plug hole, and running a = vacuum=20 line to a small suringe (like a insulin suringe). I can eyeball = the rotor=20 location close to TDC, the install this contraption and rotate the = motor=20 so the suringe moves out to the end and starts back in. then back = the=20 motor up again till the suringe tops out. I figure that outa be = and=20 accurate TDC. Whadda ya think???

Bob Mears
Supermarine=20 Spitfire

-----Original Message-----
From: Ed = Anderson <eanderson@carolina.rr.com >
To: Rotary = motors in=20 aircraft <flyrotary@lancaironline.net>
Sent: Wed, = 19 Sep=20 2007 1:16 pm
Subject: [FlyRotary] Re: Strange Ignition? =

I do not believe that is a significant = factor,=20 either, Al. After all, we're suppose to do our ignition = checks on=20 the ground before take off {:>). My understanding is that = best=20 power on the 13B has ignition timing between 25-28 deg BTDC, so = not=20 surprising that the 20B would fall in that range also. = Sounds=20 reasonable to me.

Ed

----- Original Message ----- =

From: Al = Gietzen

To: Rotary motors in=20 aircraft

Sent: Wednesday, = September 19, 2007=20 3:08 PM

Subject: [FlyRotary] Re: = Strange=20 Ignition?

I = wondered if=20 perhaps one issue was that I was doing the ignition check = static, on the=20 ground; where the combination of RPM and MAP would be different = than in=20 the air. But on checking with Tracy 's = spreadsheet on the timing settings, over a fairly broad range = above=20 about 4900 the timing is (should be) in the range of 26 to 28 = degrees=20 BTDC.

Al

Email and AIM finally together. You've gotta check out free AOL = Mail!

No virus found in this incoming message.
Checked by AVG = Free=20 Edition.
Version: 7.5.487 / Virus Database: 269.13.22/1015 - = Release=20 Date: 18/09/2007 11:53 = AM

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