X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.123] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3683202 for flyrotary@lancaironline.net; Mon, 15 Jun 2009 14:15:55 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.123; envelope-from=eanderson@carolina.rr.com Received: from computername ([75.191.186.236]) by cdptpa-omta01.mail.rr.com with ESMTP id <20090615181518840.YPL26718@cdptpa-omta01.mail.rr.com> for ; Mon, 15 Jun 2009 18:15:18 +0000 From: "Ed Anderson" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Not developing full power. Date: Mon, 15 Jun 2009 14:15:24 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0000_01C9EDC3.B9F61E50" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: Acnt2sbBwoQRnBbfQm+rSiPEFFFXhwACITuA In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Message-Id: <20090615181518840.YPL26718@cdptpa-omta01.mail.rr.com> This is a multi-part message in MIME format. ------=_NextPart_000_0000_01C9EDC3.B9F61E50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Glad to hear that your =93block=94 muffler did not cause any = =93incident=94 on your way home. The Archer Test bed for the Mistral engine had to make a = force landing because of a muffler blockage, engine continue to run, but could = not develop sufficient power =96 took the wings off the aircraft hitting = trees, but Pilot walked away OK. =20 When I was experimenting with mufflers, I had one design that looked = very promising =96 multiple discs inside the tube with blades bent on the = outside perimeter. Theory was the shock wave would see solid metal but the = exhaust gases would turn and flow around the blades. Noise was very much = reduced and power was initially quite good =96 that is until several of the = discs broke loose and started wind milling on a steel rod in the center = holding them all in place. EGT climbed from a nominal 1550F to over 1700 on = that rotor (have separate header and muffler for each rotor) and power = dropped of considerably. Oil and coolant temperatures did increase but less than happened to you =96 I presume at least in part because only one rotor = had its exhaust gas hindered in my case the other one could get rid of its = exhaust gas heat. =20 One on-looker told me later it sounded like I had a turbine =96 I guess = those spinning wheels modulated the exhaust gas. =20 I decided after than point to not use any muffler where parts could come loose and block the exhaust flow =96 with my turbo ports, its not a = question of IF but WHEN. If anything is perpendicular to the shock wave it is = sooner or later going to be pounded into pieces (more likely sooner). =20 If I should see any less than 15 gph on take off with my installation, I would probably abort the take off to see what is wrong. 16-17 gph is = the nominal with 18-20 on cold days (loves that dense air). However, based = on your comment it would seem your intake is doing the job very nicely if = your manifold pressure is near ambient at WOT. =20 Great to finally meet you, Steve. Enjoy meeting your wife, Carmen, and = hope you both make it back to this neck of the woods again.=20 =20 Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm =20 _____ =20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of sboese Sent: Monday, June 15, 2009 12:59 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Not developing full power. =20 The following observations may be of interest in the light of recent discussions. =20 =20 On the flight to the resent Rotorfest, I thought the exhaust noise level = had increased at one point. This was just chalked up to fatigue and the = longer than normal time in flight since this was the longest XC attempted to = date. My usual procedure for adjusting throttle position is to advance it = until no further increase in rpm results even though there is normally about =BC = of the total travel still available. My throttle body is a cut down Mazda one = with two openings as described in Tracy=92s guide. Since I use the stock oil metering pump, the throttle position adjusts the metering pump stroke = and advancing the throttle more than necessary results in accumulation of = oil in the sump. At one point when checking the throttle position, the RPM actually dropped slightly when advancing the throttle further. I = thought to myself =93this is strange=94 and returned the throttle to its original = setting since things were running smoothly. =20 At the Rotorfest, I listened with interest to Mark=92s presentation on = muffler lifetime or lack thereof, wondering why my first attempt at a muffler = had survived so long. I attributed this to my normal operation at high = density altitudes which results in reduced max power levels. I also described = the construction of my =93bomb=94 to several people who were interested in = it. I now realize that I didn=92t know what was in it myself. During the = preflight before leaving the Rotorfest, I noticed a rattle in the muffler when checking its security to the belly of the plane. After returning to Laramie, I investigated the rattle further and the results are shown in = the attached pictures. The fact that the center baffle broke is not = surprising since it was simply a push fit into the shell and was vulnerable to = flexing since it was flat. The repair uses a conical shaped baffle with a solid ring around its outside circumference to make it even stiffer. We=92ll = see how long that lasts. =20 The recent discussion on not developing full power, especially Ed=92s information on seeing almost 20 gph at max power settings at seal level = got me thinking about my performance. I have seen up to 16 gal/hr at 4500 = ft DA on a rare excursion to that low an altitude. That didn=92t seem = unreasonable considering the sophistication of my setup compared to Ed=92s. Looking = back at the data log from the flight home from the Rotorfest, there were some interesting observations concerning the departure from 40XS. That = segment of some of the data from the log is shown in the attached plots. =20 A couple of things in the data seem to me to stand out. One is that I = am recovering nearly full manifold pressure in the plenum at wide open = throttle compared to ambient as shown in the data of the manifold pressure before start-up and during runup and take off. This has always been the case. = The second thing that stands out is that I was only using between 10 and 11 gal/hr at wide open throttle with the mixture adjusted for max power. I didn=92t look at the fuel flow reading during runup or take off and only noticed these low values when examining the data log recently. I am confident that the fuel flow readings are quite accurate since the fuel actually used for this trip matches the instrument readout very well. = While some of you may have experienced some apprehension at such a pathetic = power production level, it seemed normal to me since I usually operate at = density altitude from 7000-10000 ft. Another thing I noticed in the data is the significant rpm drop when the prop unstalled just prior to liftoff. The = rpm usually drops a little at that point but not nearly this much. I = remember noticing this on departure, but was otherwise occupied and didn=92t give = much further thought at the time. Not shown in the plots is the coolant temperature which reached 225 degrees at the stock location in the = flywheel end iron at 8 minutes into the log. This is about 20 degrees higher = than normal even at the reduced fuel consumption level during this time. Oil temperature showed a similar response. =20 After removing the muffler to investigate the rattle, standing it on end would allow the broken segment to move to the area of the outlet and = block some of the exhaust exit area. Laying it horizontally again would allow = the broken segment to slide down the conical end where it could not be seen = in the exit. I suspect that the exhaust gas carried the broken segment up = the slope where it could block part of the exit when operating at power = levels above idle. Luckily, the blockage was not enough to prevent generating enough power to sustain flight. =20 In any case, the data log is a record of the effect of increased back pressure on the performance of my NA 13B. Just as has been described in = the recent discussions, the result was as expected: decreased max fuel consumption and decreased max power production. In addition, I saw increased coolant and oil temperatures. Maybe the increased back = pressure was responsible for the decrease in rpm upon fully opening the throttle = in stabilized flight, but I=92m not sure why such an effect would arise. =20 For what it is worth=85 =20 Steve Boese =20 __________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------=_NextPart_000_0000_01C9EDC3.B9F61E50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Glad to hear that your = “block” muffler did not cause any “incident” on your way home.=A0 = The Archer Test bed for the Mistral engine had to make a force landing because of a = muffler blockage, engine continue to run, but could not develop sufficient power = – took the wings off the aircraft hitting trees, but Pilot walked away = OK.

 

When I was experimenting with = mufflers, I had one design that looked very promising – multiple discs inside = the tube with blades bent on the outside perimeter.=A0 Theory was the shock = wave would see solid metal but the exhaust gases would turn and flow around = the blades.=A0 Noise was very much reduced and power was initially quite = good – that is until several of the discs broke loose and started wind milling = on a steel rod in the center holding them all in place.=A0 EGT climbed from a = nominal 1550F to over 1700 on that rotor (have separate header and muffler for = each rotor) and power dropped of considerably. =A0Oil and coolant = temperatures did increase but less than happened to you – I presume at least in = part because only one rotor had its exhaust gas hindered in my case the other = one could get rid of its exhaust gas heat.

 

=A0One on-looker told me later it = sounded like I had a turbine – I guess those spinning wheels modulated the exhaust gas.

 

I decided after than point to not = use any muffler where parts could come loose and block the exhaust flow – with my = turbo ports, its not a question of IF but WHEN. If anything is perpendicular = to the shock wave it is sooner or later going to be pounded into pieces (more = likely sooner).

 

If I should see any less than 15 = gph on take off with my installation, I would probably abort the take off to = see what is wrong.=A0 16-17 gph is the nominal with 18-20 on cold days (loves = that dense air).=A0 However, based on your comment it would seem your intake is = doing the job very nicely if your manifold pressure is near ambient at = WOT.

 

Great to finally meet you, = Steve.=A0 Enjoy meeting your wife, Carmen, and hope you both make it back to this neck = of the woods again.

 

Ed

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of sboese
Sent: Monday, June 15, = 2009 12:59 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Not developing full power.

 

=

The following observations may be = of interest in the light of recent discussions.  =

 

On the flight to the resent = Rotorfest, I thought the exhaust noise level had increased at one point.  This = was just chalked up to fatigue and the longer than normal time in flight since = this was the longest XC attempted to date.  My usual procedure for adjusting throttle position is to advance it until no further increase in rpm = results even though there is normally about =BC of the total travel still available.  My throttle body is a cut down Mazda one with two = openings as described in Tracy’s guide. Since I use the stock oil metering pump, the throttle position = adjusts the metering pump stroke and advancing the throttle more than necessary = results in accumulation of oil in the sump.  At one point when checking the throttle position, the RPM actually dropped slightly when advancing the throttle further.  I thought to myself “this is = strange”  and returned the throttle to its original setting since things were = running smoothly.

 

At the Rotorfest, I listened with = interest to Mark’s presentation on muffler lifetime or lack thereof, = wondering why my first attempt at a muffler had survived so long.  I attributed = this to my normal operation at high density altitudes which results in reduced = max power levels.  I also described the construction of my = “bomb” to several people who were interested in it.  I now realize that I didn’t know what was in it myself.  During the preflight = before leaving the Rotorfest, I noticed a rattle in the muffler when checking its = security to the belly of the plane.  After returning to Laramie, I investigated the rattle = further and the results are shown in the attached pictures.  The fact that = the center baffle broke is not surprising since it was simply a push fit = into the shell and was vulnerable to flexing since it was flat.  The repair = uses a conical shaped baffle with a solid ring around its outside circumference = to make it even stiffer.  We’ll see how long that = lasts.

 

The recent discussion on not = developing full power, especially Ed’s information on seeing almost 20 gph at = max power settings at seal level got me thinking about my performance.  = I have seen up to 16 gal/hr at 4500 ft DA on a rare excursion to that low an altitude.  That didn’t seem unreasonable considering the sophistication of my setup compared to Ed’s.  Looking back at = the data log from the flight home from the Rotorfest, there were some = interesting observations concerning the departure from 40XS.  That segment of = some of the data from the log is shown in the attached = plots.

 

A couple of things in the data seem = to me to stand out.  One is that I am recovering nearly full manifold = pressure in the plenum at wide open throttle compared to ambient as shown in the = data of the manifold pressure before start-up and during runup and take = off.  This has always been the case.  The second thing that stands out is that = I was only using between 10 and 11 gal/hr at wide open throttle with the = mixture adjusted for max power.  I didn’t look at the fuel flow reading during = runup or take off and only noticed these low values when examining the data = log recently.  I am confident that the fuel flow readings are quite = accurate since the fuel actually used for this trip matches the instrument = readout very well.  While some of you may have experienced some apprehension at = such a pathetic power production level, it seemed normal to me since I usually = operate at density altitude from 7000-10000 ft.  Another thing I noticed in = the data is the significant rpm drop when the prop unstalled just prior to liftoff.  The rpm usually drops a little at that point but not = nearly this much.  I remember noticing this on departure, but was otherwise = occupied and didn’t give much further thought at the time.  Not shown = in the plots is the coolant temperature which reached 225 degrees at the stock location in the flywheel end iron at 8 minutes into the log.  This = is about 20 degrees higher than normal even at the reduced fuel consumption = level during this time.  Oil temperature showed a similar = response.

 

After removing the muffler to = investigate the rattle, standing it on end would allow the broken segment to move to = the area of the outlet and block some of the exhaust exit area.  Laying = it horizontally again would allow the broken segment to slide down the = conical end where it could not be seen in the exit.  I suspect that the exhaust = gas carried the broken segment up the slope where it could block part of the = exit when operating at power levels above idle.  Luckily, the blockage = was not enough to prevent generating enough power to sustain = flight.

 

In any case, the data log is a = record of the effect of increased back pressure on the performance of my NA = 13B.  Just as has been described in the recent discussions, the result was as expected: decreased max fuel consumption and decreased max power production.  In addition, I saw increased coolant and oil temperatures.  Maybe the increased back pressure was responsible = for the decrease in rpm upon fully opening the throttle in stabilized flight, but = I’m not sure why such an effect would arise.

 

For what it is = worth…

 

Steve = Boese

 



__________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

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