X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qw-out-2122.google.com ([74.125.92.24] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3684195 for flyrotary@lancaironline.net; Tue, 16 Jun 2009 11:17:29 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.92.24; envelope-from=rwstracy@gmail.com Received: by qw-out-2122.google.com with SMTP id 8so2248161qwh.25 for ; Tue, 16 Jun 2009 08:16:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to :content-type; bh=HGOAoHfz972tjzGZD87CcaF/CIsPP0WNnQeExUc7s0s=; b=mEge4GDqPWee4wqxVaJdcKp0ACms0TjNxtw9WoaRfUIY3t5nIWEIZunZZ3ddVrZDSs B2ZpkGKMgdY8lvoqPa6HtxTCVs9u/2AYqJDR/7xZ0l+T2SLU4jzLb5Isx4yCYNMG2TGg ULLu2sVv54c+GGpiNTvmgRQlQPpFm7GNZJcuE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=LuKuO87Sk4ARsXThdBMTH6cB8k5ee1Si2e4WSUa1nTvruuGU9dcBvvlwRN/0gm+WOx RH2DjFu1+xvbRC/G398Txy/EeuradHwrgwn+Cxk4OvyYQdbKizFEkaZVbpv3i0l5JOYE YGGC1232Lg0xLUyWJOnJz0h3cYREgTWJEPeNw= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.73.146 with SMTP id q18mr8509834qaj.312.1245165414004; Tue, 16 Jun 2009 08:16:54 -0700 (PDT) In-Reply-To: References: Date: Tue, 16 Jun 2009 11:16:53 -0400 X-Google-Sender-Auth: dd58d1f31affe936 Message-ID: <1b4b137c0906160816k5d94e29oc6c53051ac9d0aa5@mail.gmail.com> Subject: Re: [FlyRotary] Re: Not developing full power. From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015175cbaa2303a04046c78aa94 --0015175cbaa2303a04046c78aa94 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable 5400 static rpm with a fixed pitch prop on a 2.17 drive is not bad, assumin= g that the prop is appropriate for a 180 HP engine on your airframe. If so, 5400 is definitely flying power. Another clue is fuel flow. If you are burning 12 - 15 gph at static WOT, it's ready to fly. FWIW, when I used the 2.17 drive my static RPM was 5200. You don't want to have too high a static rpm because the top speed rpm in flight would allow prop over speed. I picked up 1200 rpm over static at top speed. That woul= d have given me 7200 if I had 6000 static. Prop Tip speed would have been supersonic (bad). Hope this makes sense. Tracy On Tue, Jun 16, 2009 at 9:52 AM, Bill Bradburry w= rote: > Steve, > > What results has your repaired muffler given you? > > It strikes me that you should be able to get over 6K static (and take off= ) > RPM with the 2.17 drive. That shouldn=92t change much with altitude I th= ink. > You will have less air for the engine to breathe, but it will be easier f= or > the prop to turn in the thinner air. You were getting about 5K on your t= ake > off and climb from Texas. Your climb rate was only about 400 fpm also. = You > lifted off at close to 1K feet at 6 minutes and reached close to 4K feet = at > 14 minutes. Lets say 3200 ft in 8 minutes. At higher altitudes I don=92= t > know if you could climb.?? Do you think all this was caused by the muffl= er? > > Your prop rpm was right in there with your indicated airspeed. Both were > about 148-149 mph at cruise. > > If you still have throttle left after the engine maxes out, I think that > indicates a problem of some kind. I encourage you to try and discover wh= at > causes it. One reason is that I am having the same situation! :>) My > static is around 5400 rpm max and there is still throttle left. I am sti= ll > working on my cooling, so I can not run the engine. But I don=92t think = I am > developing enough power to try to fly. > > Where did you get the data? > > > > Bill B > > > > > ------------------------------ > > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] *O= n > 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 i= t > until no further increase in rpm results even though there is normally ab= out > =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 st= ock > 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 R= PM > actually dropped slightly when advancing the throttle further. I thought= to > myself =93this is strange=94 and returned the throttle to its original s= etting > since things were running smoothly. > > > > 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 a= t > 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 myse= lf. > 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 a= re > 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 shape= d > baffle with a solid ring around its outside circumference to make it even > stiffer. We=92ll see how long that lasts. > > > > The recent discussion on not developing full power, especially Ed=92s > information on seeing almost 20 gph at max power settings at seal level g= ot > 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 unreason= able > considering the sophistication of my setup compared to Ed=92s. Looking b= ack > at the data log from the flight home from the Rotorfest, there were some > interesting observations concerning the departure from 40XS. That segmen= t > 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 throt= tle > 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. Wh= ile > some of you may have experienced some apprehension at such a pathetic pow= er > production level, it seemed normal to me since I usually operate at densi= ty > 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 remembe= r > 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 flywhe= el > 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 bloc= k > 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 i= n > the exit. I suspect that the exhaust gas carried the broken segment up t= he > slope where it could block part of the exit when operating at power level= s > 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 pressur= e > was responsible for the decrease in rpm upon fully opening the throttle i= n > stabilized flight, but I=92m not sure why such an effect would arise. > > > > For what it is worth=85 > > > > Steve Boese > > > --0015175cbaa2303a04046c78aa94 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable 5400 static rpm with a fixed pitch prop on a 2.17 drive is not bad, assumin= g that the prop is appropriate for a 180 HP engine on your airframe.=A0 If = so, 5400 is definitely flying power.=A0 Another clue is fuel flow.=A0 If yo= u are burning 12 - 15 gph at static WOT, it's ready to fly.

FWIW, when I used the 2.17 drive my static RPM was 5200.=A0 You don'= ;t want to have too high a static rpm because the top speed rpm in flight w= ould allow prop over speed.=A0 I picked up 1200 rpm over static at top spee= d.=A0 That would have given me 7200 if I had 6000 static.=A0 Prop Tip speed= would have been supersonic (bad).

Hope this makes sense.

Tracy=A0

On Tue, Jun 16, 2009 at 9:52 AM, Bill Bradburry <bbradburry@bellsouth.net><= /span> wrote:

Steve,

What results has your repaired muffler given you?=A0

It strikes me that you should be able to get over 6K static (and take off) RPM with the 2.17 drive.=A0 That shouldn=92t change much with altitude= I think.=A0 You will have less air for the engine to breathe, but it will be = easier for the prop to turn in the thinner air.=A0 You were getting about 5K on yo= ur take off and climb from Texas.=A0 Your climb rate was only about 400 fpm also.=A0 You lifted off at close to = 1K feet at 6 minutes and reached close to 4K feet at 14 minutes.=A0 Lets say 3= 200 ft in 8 minutes.=A0 At higher altitudes I don=92t know if you could climb.??= =A0 Do you think all this was caused by the muffler?

Your prop rpm was right in there with your indicated airspeed.=A0 Both w= ere about 148-149 mph at cruise. =A0

If you still have throttle left after the engine maxes=A0 out, I think that indicates a problem of some kind.=A0 I encourage you to try and discov= er what causes it.=A0 One reason is that I am having the same situation!=A0 :>)= =A0 My static is around 5400 rpm max and there is still throttle left.=A0 I am sti= ll working on my cooling, so I can not run the engine.=A0 But I don=92t think = I am developing enough power to try to fly.

Where did you get the data?

=A0

Bill B

=A0

=A0

From: Rotary motors in aircraft [mailto:fl= yrotary@lancaironline.net] On Behalf Of sboese
Sent: Monday, June 15, 200= 9 12:59 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: N= ot developing full power.

The following observations may be of interes= t in the light of recent discussions.=A0

=A0

On the flight to the resent Rotorf= est, I thought the exhaust noise level had increased at one point.=A0 This was jus= t chalked up to fatigue and the longer than normal time in flight since this = was the longest XC attempted to date.=A0 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.=A0 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 adjus= ts the metering pump stroke and advancing the throttle more than necessary res= ults in accumulation of oil in the sump.=A0 At one point when checking the throttle position, the RPM actually dropped slightly when advancing the throttle further.=A0 I thought to myself =93this is strange=94=A0 and returned the throttle to its original setting since things were running smoothly.

=A0

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.=A0 I attributed this to my normal operation at high density altitudes which results in reduced max power levels.=A0 I also described the construction of my =93bomb=94 to several people who were interested in it.=A0 I now realize that I didn=92t know what was in it myself.=A0 During the preflight before leaving the Rotorfest, I noticed a rattle in the muffler when checking its security to the belly of the plane.=A0 After returning to Laramie, I invest= igated the rattle further and the results are shown in the attached pictures.=A0 The fact that the center baffle broke is not surprising since it was simply a push fit into t= he shell and was vulnerable to flexing since it was flat.=A0 The repair uses a conical shaped baffle with a solid ring around its outside circumference to make it even stiffer.=A0 We=92ll see how long that lasts.

=A0

The recent discussion on not devel= oping full power, especially Ed=92s information on seeing almost 20 gph at max power settings at seal level got me thinking about my performance.=A0 I hav= e seen up to 16 gal/hr at 4500 ft DA on a rare excursion to that low an altitude.=A0 That didn=92t seem unreasonable considering the sophistication of my setup compared to Ed=92s.=A0 Looking back at the data log from the flight home from the Rotorfest, there were some interesti= ng observations concerning the departure from 40XS. =A0That segment of some of the data from the log is shown in the attached plots.

=A0

A couple of things in the data see= m to me to stand out.=A0 One is that I am recovering nearly full manifold pressure in the plenum at wide open throttle compared to ambient as shown in the dat= a of the manifold pressure before start-up and during runup and take off.=A0 Thi= s has always been the case.=A0 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.=A0 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.=A0 I am confident that the fuel flow readings are quite accurate since the fuel actually used for this trip matches the instrument readout v= ery well.=A0 While some of you may have experienced some apprehension at such a pathetic power production level, it seemed normal to me since I usually ope= rate at density altitude from 7000-10000 ft.=A0 Another thing I noticed in the data is the significant rpm drop when the prop unstalled just prior to liftoff.=A0 The rpm usually drops a little at that point but not nearly thi= s much.=A0 I remember noticing this on departure, but was otherwise occupied and didn=92t give much further thought at the time.=A0 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.=A0 This is about 20 degrees higher than normal even at the reduced fuel consumption le= vel during this time.=A0 Oil temperature showed a similar response.

=A0

After removing the muffler to inve= stigate the rattle, standing it on end would allow the broken segment to move to th= e area of the outlet and block some of the exhaust exit area.=A0 Laying it horizontally again would allow the broken segment to slide down the conical= end where it could not be seen in the exit.=A0 I suspect that the exhaust gas carried the broken segment up the slope where it could block part of the ex= it when operating at power levels above idle.=A0 Luckily, the blockage was not enough to prevent generating enough power to sustain flight.<= /p>

=A0

In any case, the data log is a rec= ord of the effect of increased back pressure on the performance of my NA 13B.=A0 Just as has been described in the recent discussions, the result was as expected: decreased max fuel consumption and decreased max power production.=A0 In addition, I saw increased coolant and oil temperatures.=A0 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.

=A0

For what it is worth=85

=A0

Steve Boese

= =A0


--0015175cbaa2303a04046c78aa94--