X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.3.3) with ESMTP id 4154322 for flyrotary@lancaironline.net; Sat, 06 Mar 2010 06:11:39 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.0 c=1 a=hCNxu-qUHAUA:10 a=ayC55rCoAAAA:8 a=arxwEM4EAAAA:8 a=QdXCYpuVAAAA:8 a=7g1VtSJxAAAA:8 a=ekHE3smAAAAA:20 a=UretUmmEAAAA:8 a=Ia-xEzejAAAA:8 a=nUuTZ29dAAAA:8 a=KNMvZf3fChRQbMq1P9UA:9 a=-ArM8LhD38p_WMYXo2oA:7 a=sFr0t22ARQ371oW1vucGC9AzJjAA:4 a=wPNLvfGTeEIA:10 a=1vhyWl4Y8LcA:10 a=EzXvWhQp4_cA:10 a=R7HqDBVStYJosDE0:21 a=sPYYr-FQ6OMy12jB:21 a=SSmOFEACAAAA:8 a=1PdRdCFvw6n-V-BQJM4A:9 a=sN6gUixrSgn86w91LuEA:7 a=cnw5RfvqQZDr9ldGdVDYC4oRv7EA:4 a=fYeKLouQMIs6kkPJ:21 a=PXV102xdYpF_1AKW:21 X-Cloudmark-Score: 0 X-Originating-IP: 75.191.186.236 Received: from [75.191.186.236] ([75.191.186.236:3579] helo=computername) by cdptpa-oedge02.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id 57/92-22814-648329B4; Sat, 06 Mar 2010 11:11:03 +0000 From: "Ed Anderson" Message-ID: <57.92.22814.648329B4@cdptpa-omtalb.mail.rr.com> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: TB size, Travel and Power Date: Sat, 6 Mar 2010 06:11:11 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01CABCF3.D1B18F70" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 In-Reply-To: Thread-Index: Acq87jWKxOJpIw+vSt2GOxrSlWoW0QAKQugA X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_0006_01CABCF3.D1B18F70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable You=92re correct, Mike. Perhaps I should have explicitly stated that the = air density I was mentioning is the air density at the intake port =96 by = saying manifold air density =96 I left some vagueness on where in the manifold = I was referring to. However =96 it really doesn=92t matter what you measure = or where you measure it =96 the engine doesn=92t know nor care. What = matters is the actual manifold pressure/air density in the intake manifold at the intake port as that is what shoves the mixture into the combustion = chamber (plus a little help from inertia of the air mass flow and FAW waves and = just a few other things). The point is regardless of what your TB intake = design is like once you reach ambient pressure/air density in the intake = manifold (or as close as your are going to it get due to TB or intake losses), that=92s it. You have maxed out on power regardless of Throttle plate position or where you are measuring it. =20 If you are measuring ambient right after the TB but something less in = the intake manifold next to the intake port =96 then as you suggested that = would be a reflection of intake losses. But regardless you still have = manifold pressure/air density =3D Ambient Pressure/density - intake loss. As you = know, intake loss may be caused by such things as air filter, throttle body partial throttle, intake runner loses, port intake losses and others = such as interaction of FAW inside the intake. But again the engine doesn=92t = know or care =96 all it knows is the air density at the manifold intake port. = Once that is ambient or as close as the intake losses permit then additional throttle opening will not do anything for you. Now this all refers to a =93Normal=94 intake set up. There are things that you can do to change = this - like turbo charging or using Dynamic Effect Intake design. =20 Yes, a well designed DIE/DEI intake manifold temporarily results in a localized high pressure region at the intake port for a few milliseconds = =96 what happens is the extremely powerful (but very short duration) pulse generated in the intake when a intake port opened by the exhaust gas pressure still present due to the intake/exhaust overlap case of the old 13B. This pulse then hit the opposite end of the intake (the other = rotor=92s intake ports) and locality pressurize the area of the intake port just = as that rotor was closing the intake port. =20 Reversion is a well known engine process, whereby as the piston/rotor = moves from its maximum volume area on intake into the compression stroke =96 = some of the intake charge previously drawn into the combustion chamber is forced = out before the port closes. Estimates I have seen puts this =93lost=94 = charge at around 15% of the total intake charge. Perhaps just a coincident, but = that turns out to be the % power increase at 6000 rpm that the Mazda = engineers reported using the DIE intake on the older 13B. The Renesis also makes = use of the DIE effect, but it is different in several aspects =96 Dennis has worked all of that out. =20 The DIE effect does not in itself directly increase the density in the combustion chamber =96 but if timed right =96 arrives at the intake port = just as its starting to close and in effect stops or minimizes this revision = effect. So I guess since the end result is there is more air inside the same = volume =96 it has the effect of retaining the combustion chamber air density = rather than having it drop due to Revision. But, if you have a normal = manifold pressure sensor even at the intake port =96 you would probably not see = any increase in pressure =96 its over in a few milliseconds. Now with = special sensors you can indeed detect the temporary increase in localized = pressure there. =20 But, my original intention was simply to try to explain =96 perhaps = poorly =96 how you can get throttle travel without an increase in power and why. = And some of the factors that can cause that effect which are many. But, the = two dominate factors are rpm (load on the engine) and volumetric efficiency. I am certainly in agreement with the desire for all the power you can = get =96 even if I only use it for take off {:>). Just need to examine the = situation so you make the correct decisions about what is needed to obtain more = power =96 and when/how you can tell that is the most power you are going to = make. Once you trim the prop that is an irrevocable decision =96 so you want = to make as certain as you can that it is the best one. Ok, I=92ll let it rest {:>) Best Regards 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 Mike Wills Sent: Saturday, March 06, 2010 12:30 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: TB size, Travel and Power =20 Ed, =20 I hear what your saying (and I get it). Here's the thing, and I admit I = may have a misunderstanding here. Your explanation applies if you are = measuring manifold pressure essentially at the rotor face. If you measure MP = closer to the TB as I do unfortunately, it is possible to see ambient at full = throttle but have restrictions in the intake tract that would result in less than ambient at the rotor face. Conversely (and again theory - I'm open to = being shown wrong here), a properly designed DIE manifold would show ambient = MP measured at the TB and greater than ambient measured at the rotor face. =20 I accept that by trimming the prop I can lighten the load and gain some = HP (though some here seem to think that HP will increase linearly with RPM = to infinity and I don=92t buy that either). But as you alluded to in your previous, there's some potential for mistake in trimming any prop until = you are quite sure that you are not HP limited by something other than load. = And I'm not sure yet. Just a feeling based on the fact that I'm using a cut = down RX-7 TB that=92s maxed out about 1/3 short of fully open. And honestly I = still havent dug any deeper because the airplane is flying well and has good performance. But sooner or later I'm going to want to get more than the 5700RPM I'm currently getting - I want all the performance that=92s = there. =20 Mike Wills =20 From: Ed Anderson=20 Sent: Friday, March 05, 2010 6:36 PM To: Rotary motors in aircraft=20 Subject: [FlyRotary] TB size, Travel and Power =20 I am apparently not doing a very good job making the point about the relationship between throttle body size, throttle travel and engine = power clear. So here is another try at it - using extreme examples and no = math. Let=92s assume your volumetric efficiency is 100% (no losses). =20 IF you put a =BD =94 dia TB on you engine. You could have it wide open = and your engine (under normal prop load) probably wouldn=92t turn 4000 rpm. That = is because even wide open, the =BD=94 dia TB restricts airflow sufficiently = - that the manifold air density never approaches the ambient air density. = Since we know that the engine power is directly proportional to the density of = air in the combustion chamber =96 and this density is limited in this case to = less than ambient, you engine is not going to produce much power, certainly = not full power. So this bit of information tells us =93Bigger Lithium = Crystals, Scotty!!=94 =96 i.e try a larger throttle body.=20 =20 Now if you keep enlarging the diameter of the TB you would find that at fully open -your engine would be producing more power than it was, but perhaps still not the maximum power it is capable of. This is because = the air density in the manifold has increase due to the less restrictive = flow, but is still below ambient. This is due to the better, but still restrictive effect of the TB size on the air flow. Now if you continued enlarging the TB size, you would reach a point where with the TB just reaching fully open - your manifold air density is exactly ambient and = your engine is producing all the power it is going to. =20 Now if you enlarge the TB even further, you will simply find that you = can cause the manifold pressure (air density) to reach ambient without = opening the TB fully. Its simply large enough that all the air the engine can = use (ambient air density point) is met at partial throttle opening. In = fact , you can certainly continue to advance the throttle thereby opening the throttle plate even more =96 but, you are not going to increase the air density in the manifold and therefore you will not produce any = additional power for that additional throttle travel. =20 Bigger Throttle body=92s result in more power only up to the point the = airflow they permit causes manifold air density to reach ambient. Beyond that point, the only thing they do is provide frustration =96 by having all = that throttle travel remaining which does nothing to produce more power {:>). =20 Now if you can somehow lighten the load on your engine, then engine can turn faster providing more =93suction=94 on the manifold volume reducing = the air density below ambient, now opening your =93oversize=94 TB a bit more = will produce more power because you are increasing the airflow again to the = point where the equilibrium point between ambient air density in the manifold = and rpm is again reached. Lighten the load further and you can again = increase engine power by opening your TB more. Etc, etc. =20 =20 Ah, ain=92t this hobby wonderful {:>)=20 =20 =20 Ed =20 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 __________ 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_0006_01CABCF3.D1B18F70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

You’re correct, Mike. Perhaps = I should have explicitly stated that the air density I was mentioning is = the air density at the intake port – by saying manifold air density = – I left some vagueness on where in the manifold I was referring to.=A0 = =A0=A0However – it really doesn’t matter what you measure or where you measure it = – the engine doesn’t know nor care.=A0 What matters is the actual = manifold pressure/air density in the intake manifold at the intake port as that = is what shoves the mixture into the combustion chamber (plus a little help from = inertia of the air mass flow and FAW waves and just a few other things).=A0 The = point is regardless of what your TB intake design is like once you reach ambient = pressure/air density in the intake manifold (or as close as your are going to it = =A0get due to TB or intake losses), that’s it.=A0 You have maxed out on power = regardless of Throttle plate position or where you are measuring = it.

 

If you are measuring ambient right = after the TB but something less in the intake manifold next to the intake port – then as you suggested that would be a reflection of intake = losses. =A0But regardless you still have manifold pressure/air density =3D Ambient Pressure/density - intake loss. As you know, =A0intake loss may be = caused by such things as air filter, throttle body partial throttle, intake runner = loses, port intake losses and others such as interaction of FAW inside the = intake.=A0 But again the engine doesn’t know or care – all it knows is the = air density at the manifold intake port. Once that is ambient or as close as = the intake losses permit then additional throttle opening will not do = anything for you.=A0 Now this all refers to a “Normal” intake set up.=A0 There are things that you can do to change this - like = turbo charging =A0or using Dynamic Effect Intake = design.

 

Yes, a well designed DIE/DEI intake manifold temporarily results in a localized high pressure region at the = intake port for a few milliseconds – what happens is the extremely = powerful (but very short duration) pulse generated in the intake when a intake port = opened by the exhaust gas pressure still present due to the intake/exhaust overlap = case of the old 13B.=A0 This pulse then hit the opposite end of the intake = (the other rotor’s intake ports) and locality pressurize the area of the = intake port just as that =A0rotor was closing the intake = port.

 

Reversion is a well known engine = process, whereby as the piston/rotor moves from its maximum volume area on intake = into the compression stroke – some of the intake charge previously = drawn into the combustion chamber is forced out before the port closes.=A0 = Estimates I have seen puts this “lost” charge at around 15% of the total = intake charge. Perhaps just a coincident, but =A0that turns out to be the % = power increase at 6000 rpm that the Mazda engineers reported using the DIE = intake on the older 13B.=A0 The Renesis also makes use of the DIE effect, but it = is different in several aspects – Dennis has worked all of that = out.

 

The DIE effect does not in itself = directly increase the density in the combustion chamber – but if timed = right – arrives at the intake port just as its starting to close and in effect = stops or minimizes this revision effect. So I guess since the end result is there = is more air inside the same volume – it has the effect of retaining = the combustion chamber air density rather than having it drop due to = Revision.=A0 =A0But, =A0if you have a normal manifold pressure sensor even at the intake port = – you would probably not see any increase in pressure – its over in = a few milliseconds.=A0 Now with special sensors you can indeed detect the = temporary increase in localized pressure there.

 

But, my original intention was = simply to try to explain – perhaps poorly – how you can get throttle = travel without an increase in power and why.=A0 And some of the factors that = can cause that effect which are many.=A0 But, the two dominate factors are rpm = (load on the engine) and volumetric efficiency.

I am certainly in agreement with the = desire for all the power you can get – even if I only use it for take off = {:>).=A0 Just need to examine the situation so you make the correct decisions = about what is needed to obtain more power – and when/how you can tell that is = the most power you are going to make.=A0 Once you trim the prop that is an irrevocable decision – so you want to make as certain as you can = that it is the best one.

Ok, I’ll let it rest = {:>)

Best Regards

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.r= otaryaviation.com/Rotorhead%20Truth.htm

From: = Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On Behalf Of Mike = Wills
Sent: Saturday, March 06, = 2010 12:30 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = TB size, Travel and Power

 

Ed,

 

 I hear what your saying (and I get = it). Here's the thing, and I admit I may have a misunderstanding here. Your explanation applies if you are measuring manifold pressure = essentially at the rotor face. If you measure MP closer to the TB as I do = unfortunately, it is possible to see ambient at full throttle but have restrictions in = the intake tract that would result in less than ambient at the rotor face. Conversely (and again theory - I'm open to being shown wrong here), a = properly designed DIE manifold would show ambient MP measured at the TB and = greater than ambient measured at the rotor face.

 

I accept that by trimming the prop I can lighten = the load and gain some HP (though some here seem to think that HP will increase = linearly with RPM to infinity and I don’t buy that either). But as you = alluded to in your previous, there's some potential for mistake in trimming = any prop until you are quite sure that you are not HP limited by something other = than load. And I'm not sure yet. Just a feeling based on the fact that I'm = using a cut down RX-7 TB that’s maxed out about 1/3 short of fully open. = And honestly I still havent dug any deeper because the airplane is flying = well and has good performance. But sooner or later I'm going to want to get = more than the 5700RPM I'm currently getting - I want all the performance that’s there.

 

Mike Wills

 

From: Ed Anderson

Sent: Friday, March 05, 2010 6:36 PM

Subject: [FlyRotary] TB size, Travel and Power

 

I am apparently not doing a very good job making the = point about the relationship between throttle body size, throttle travel and = engine power clear.  So here is another try at it - using extreme examples = and no math.  Let’s assume your volumetric efficiency is 100% (no = losses).

 

IF you put a =BD ” dia TB on you engine.  = You could have it wide open and your engine (under normal prop load) probably wouldn’t turn 4000 rpm.  That is because even wide open, the =BD” dia TB restricts airflow sufficiently - that the manifold air = density never approaches the ambient air density.  Since we know that the = engine power is directly proportional to the density of air in the combustion = chamber – and this density is limited in this case to less than ambient, = you engine is not going to produce much power, certainly not full = power.  So this bit of information tells us “Bigger Lithium Crystals, Scotty!!” – i.e  try a larger throttle body. =

 

Now if you keep enlarging the diameter of the TB you = would find that at fully open -your engine would be producing more power than = it was, but perhaps still not the maximum power it is capable of.  This is = because the air density in the manifold has increase due to the less restrictive = flow, but is still below ambient.  This is due to the better, but still restrictive effect of the TB size on the air flow.  Now if you = continued enlarging the TB size, you would reach a point where with the TB just = reaching fully open - your manifold air density is exactly ambient and your = engine is producing all the power it is going to.

 

Now if you enlarge the TB even further, you will = simply find that you can cause the manifold pressure (air density) to reach ambient = without opening the TB fully.  Its simply large enough that all the air the = engine can use (ambient air density point)  is met at partial throttle = opening.  In fact , you can certainly continue to advance the throttle thereby = opening the throttle plate even more – but, you are not going to increase = the air density in the manifold and therefore you will not produce any = additional power for that additional throttle travel.

 

Bigger Throttle body’s result in more power = only up to the point the airflow they permit causes manifold air density to reach ambient.  Beyond that point, the only thing they do is provide = frustration – by having all that throttle travel remaining which does nothing = to produce more power {:>).

 

Now if you can somehow  lighten the load on your engine, then engine can turn faster providing more “suction” = on the manifold volume reducing the air density below ambient, now opening your “oversize” TB a bit more will produce more power because you = are increasing the airflow again to the point where the equilibrium point = between ambient air density in the manifold and rpm is again reached.  = Lighten the load further and you can again increase engine power by opening your TB = more. Etc, etc.

 

 

Ah, ain’t this hobby wonderful {:>) =

 

 

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.r= otaryaviation.com/Rotorhead%20Truth.htm

 



__________ 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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