X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-qy0-f204.google.com ([209.85.221.204] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3684329 for flyrotary@lancaironline.net; Tue, 16 Jun 2009 13:10:01 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.221.204; envelope-from=rwstracy@gmail.com Received: by qyk42 with SMTP id 42so5803548qyk.7 for ; Tue, 16 Jun 2009 10:09:24 -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=2aMZ7uDrKLxCqbNy5WIQ+gXfytmNe6B8fmMDapTK0Ok=; b=K2gJm4TRbUSj3vH//okYpXEn9tFipFAHV3hTQV/JoCFeQDyyKdnRS9kMcKOzUy6MTA JvprzQlEeiPWLie+f0E9O1KqvdIn/69OPsxy95i/vB1J9ZLEEVtRVpPnyZ9vGpR4oCYN PV6/8A9B2BbLyl9ExVzzt/jwH9RVXdXMToS/Q= 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=v25hR4lgsVuIvffNj1qDeqEIf6uxRRh+y43ONtE1qDqTRmp6Z8syPmYGBIz1fG0MA1 m91dWNdxZFYS+F8PDvy7jK3YmCZjCz4KQy45v8v9Z8MfE684NYs2riQmB7X8eg9n1oMI KoYRVHr58R4OnCRxl7DM0HHRTmDYy37Inu590= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.73.146 with SMTP id q18mr8663810qaj.312.1245172164893; Tue, 16 Jun 2009 10:09:24 -0700 (PDT) In-Reply-To: References: Date: Tue, 16 Jun 2009 13:09:24 -0400 X-Google-Sender-Auth: 3a4b3b27477fce0e Message-ID: <1b4b137c0906161009k75d63d70k861f8ca54499d8c1@mail.gmail.com> Subject: Re: [FlyRotary] Re: Not developing full power. From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015175cbaa2929e68046c7a3cb9 --0015175cbaa2929e68046c7a3cb9 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable 10 - 11 GPH is little low for those conditions and 400 fpm is very low for an RV at sea level. I'm using your numbers here because I didn't see Steve's reported numbers or conditions when measured. See my previous comments about the 2/3 throttle position. Do these these numbers apply to Steve's partially blocked exhaust condition? That would explain a lot this. That being the case, I wouldn't try to conclude anything until the known problem was resolved. Tracy On Tue, Jun 16, 2009 at 11:41 AM, Bill Bradburry wrote: > Tracy, > > I got my mind backwards again! The 2.17 is like maybe running in third > gear, while the 2.85 is like running in second. The RPM would be lower f= or > the 2.17. > > But what do you think about his fuel flow of 10-11 gph and the climb rate > of 400? Do those seem really low for 1000 MSL? > > What do you think about the 2/3 use of the throttle? > > > > Bill B > > > ------------------------------ > > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] *O= n > Behalf Of *Tracy Crook > *Sent:* Tuesday, June 16, 2009 11:17 AM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Not developing full power. > > 5400 static rpm with a fixed pitch prop on a 2.17 drive is not bad, > assuming that the prop is appropriate for a 180 HP engine on your airfram= e. > If so, 5400 is definitely flying power. Another clue is fuel flow. If y= ou > 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 allo= w > prop over speed. I picked up 1200 rpm over static at top speed. That wo= uld > 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 > wrote: > > 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 > > > > > --0015175cbaa2929e68046c7a3cb9 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable 10 - 11 GPH is little low for those conditions and 400 fpm is very low for = an RV at sea level.=A0 I'm using your numbers here because I didn't= see Steve's reported numbers or conditions when measured. =A0 See my p= revious comments about the 2/3=A0 throttle position.

Do these these numbers apply to Steve's partially blocked exhaust c= ondition?=A0 That would explain a lot this.=A0 That being the case, I would= n't try to conclude anything until the known problem was resolved.
<= br> Tracy

On Tue, Jun 16, 2009 at 11:41 AM, = Bill Bradburry <bbradburry@bellsouth.net> wrote:

Tracy,

I got my mind backwards again!=A0 The 2.17 is like maybe running in thir= d gear, while the 2.85 is like running in second.=A0 The RPM would be lower f= or the 2.17.=A0

But what do you think about his fuel flow of 10-11 gph and the climb rate of 400?=A0 Do those seem really low for 1000 MSL?

What do you think about the 2/3 use of the throttle?

=A0

Bill B

=A0

From: Rotary motors in aircraft [mailto:fl= yrotary@lancaironline.net] On Behalf Of Tracy Crook
Sent: Tuesday, June 16, 20= 09 11:17 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: N= ot developing full power.

5400 static rpm with a fixed pitch prop on a 2.17 drive is not bad, assuming 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 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.=A0 You don't w= ant to have too high a static rpm because the top speed rpm in flight would all= ow prop over speed.=A0 I picked up 1200 rpm over static at top speed.=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> = 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 5= K on your 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 sa= y 3200 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?<= /p>

Your prop rpm was right in there with your indicated airspeed.=A0 Both were 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 discover 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 still 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:flyrotary@lancaironlin= e.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 just chalked up to fatigue and the longer than normal time in flight since this was the longes= t 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. Sin= ce I use the stock oil metering pump, the throttle position adjusts the metering pump stroke a= nd advancing the throttle more than necessary results in accumulation of oil i= n 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 norma= l operation at high density altitudes which results in reduced max power leve= ls.=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 investigated 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 the 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 have 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 interesting 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 data of the manifold pres= sure before start-up and during runup and take off.=A0 This 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 lift= off.=A0 The rpm usually drops a little at that point but not nearly this 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 the area of th= e 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 th= e broken segment up the slope where it could block part of the exit 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 bee= n 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 pressur= e 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

=A0


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