X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.122] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3684342 for flyrotary@lancaironline.net; Tue, 16 Jun 2009 13:09:06 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.122; envelope-from=eanderson@carolina.rr.com Received: from computername ([75.191.186.236]) by cdptpa-omta02.mail.rr.com with ESMTP id <20090616170827315.LAXF22702@cdptpa-omta02.mail.rr.com> for ; Tue, 16 Jun 2009 17:08:27 +0000 From: "Ed Anderson" To: "'Rotary motors in aircraft'" Subject: 10-11 GPH = Re: Not developing full power. Date: Tue, 16 Jun 2009 13:08:35 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0003_01C9EE83.8E951070" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: AcnumQxEIcN57Xy1QTyjGw/Rzt4bIAACnrDQ In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Message-Id: <20090616170827315.LAXF22702@cdptpa-omta02.mail.rr.com> This is a multi-part message in MIME format. ------=_NextPart_000_0003_01C9EE83.8E951070 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable =20 I agree with Tracy, when I had a 2.17:1 and a 68x72 prop producing = 5200-5400 static gave plenty of power for an RV-6A to fly on. Top speed was 196 = MPH TAS and ROC loaded was around 900-1100 fpm. Going to the 2.85 and a = much larger prop 74x88 gave me a static of 6000-6200 and greatly added oomph = to take off acceleration and climbout. =20 However, 10-11 GPH equates to around 100-110 HP which seems low for 1000 = MSL =96 assuming that was WOT. But, some folks may pull back on power to = prevent overheating after takeoff. =20 =20 If you=92re fuel flow is accurate then that puts a top end limit on your = power being produced =96 but not necessarily a lower limit as the rotor will = past through considerably more fuel without bogging than a piston engine. So = you may be showing 20 gph =96 which if was producing power would give you = close to 200HP =96 however, you could be producing less HP and simply blowing = fuel through the engine. But, fuel flow, manifold pressure and engine rpm = are three primary factors in estimating HP. =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 Bill Bradburry Sent: Tuesday, June 16, 2009 11:42 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Not developing full power. =20 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 = for the 2.17.=20 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? =20 Bill B =20 _____ =20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On 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 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 = would have given me 7200 if I had 6000 static. Prop Tip speed would have been supersonic (bad). Hope this makes sense. Tracy =20 On Tue, Jun 16, 2009 at 9:52 AM, Bill Bradburry = wrote: Steve, What results has your repaired muffler given you? =20 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 = think. You will have less air for the engine to breathe, but it will be easier = for the prop to turn in the thinner air. You were getting about 5K on your = take 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=92t know if you could climb.?? Do you think all this was caused by the = muffler? Your prop rpm was right in there with your indicated airspeed. Both = were about 148-149 mph at cruise. =20 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 = what 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 = still 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? =20 Bill B =20 =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. 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 =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_0003_01C9EE83.8E951070 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

 

I agree with Tracy, when I had a 2.17:1 and a = 68x72 prop producing 5200-5400 static gave plenty of power for an RV-6A to fly = on.=A0 Top speed was 196 MPH TAS and ROC loaded was around 900-1100 fpm.=A0 Going = to the 2.85 and a much larger prop 74x88 gave me a static of 6000-6200 and = greatly added oomph to take off acceleration and = climbout.

 

However, 10-11 GPH equates to = around 100-110 HP which seems low for 1000 MSL – assuming that was = WOT.=A0 But, some folks may pull back on power to prevent overheating after = takeoff.=A0

 

If you’re fuel flow is = accurate then that puts a top end limit on your power being produced – but not necessarily a lower limit as the rotor will past through considerably = more fuel without bogging than a piston engine.=A0 So you may be showing 20 gph = – which if was producing power would give you close to 200HP – = however, you could be producing less HP and simply blowing fuel through the = engine.=A0 But, fuel flow, manifold pressure and engine rpm are three primary factors in estimating HP.

 

Ed

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Bradburry
Sent: Tuesday, June 16, = 2009 11:42 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Not developing full power.

 

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 for 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] On 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 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 would 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 <bbradburry@bellsouth.net>= 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’t change much with altitude I think.  You will have less air for the = engine to breathe, but it will be easier for the prop to turn in the thinner air.  You were getting about 5K on your take 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’t know if you could climb.??  Do you think all this was caused by the = muffler?

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 what 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 still working on my cooling, so I can not run the engine.  But I don’t 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] 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

------=_NextPart_000_0003_01C9EE83.8E951070--