X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from web83915.mail.sp1.yahoo.com ([69.147.92.125] verified) by logan.com (CommuniGate Pro SMTP 5.3.7) with SMTP id 4328126 for flyrotary@lancaironline.net; Thu, 27 May 2010 10:50:13 -0400 Received-SPF: none receiver=logan.com; client-ip=69.147.92.125; envelope-from=keltro@att.net Received: (qmail 45728 invoked by uid 60001); 27 May 2010 14:49:37 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=att.net; s=s1024; t=1274971776; bh=mF1Oshyug9BD1ABEN+isErrndqEIePiI3/rcED1yuio=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=IzjnMNguAVjjk+G2qCH97raeZjrNmb5NCsA3ZkSvYfCy73Xq1FlTDOouHiFjjGWacRz7dv+ooQbROefWsRs2duXzMXc+C1CXGEWQrpSWfuP4abUl0oXM+84fgItZp4MUor8H2A+63ADCOp0+O8UxKAMHImWgwpuRxZmHTm2FKxU= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=att.net; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=A5gaft3rzVlW4uRJIvpp8npHM+6oCYoINE0NGFubLVTO2ZB5ryYYKyzby0QqvdDJXOZuLHMZ7ZM269wy29dEQPoi+mJWFFcumC3P85nCy05XqzWtXzQNovkAlvm0zDA7+Vr4Zfa+lzJXXuQEYw6I3QHIS+i1C59uooCdLaBZvZQ=; Message-ID: <937052.45262.qm@web83915.mail.sp1.yahoo.com> X-YMail-OSG: PxjC9WUVM1kv4g2XKu5h2NSUP0xcYRIlwnxSOAgvebWa5YI 74MfxUBPGNSHRLQ5ydATe42ec4ruPj0.hmlDJYPrAIsb8jMiQ2uHujq9C49Q 8Ia_iqRx_RQbBldsvosruy9KFuHcqnw9AKpr0jn0JY8YNhzoSJmYecL.ZMPa WvwNHoJDwDjFSIjoabFnul361hfshxH6RLVkOD7s68cbH8P.6KqzqTjPId6. Y7XNHFx2YBA5wIrErJsFKnbG692GlYIlst9EHWpEAXAz.fcMIqs4CxrEdTzs J97N1R2i70YX3Gf5WYr65XGu6MUE7NQXn.OKRlH8QLeGhUKU6hmsHtyOVXyJ k2g0mWeUO9IlsCNlSrLo- Received: from [208.114.40.144] by web83915.mail.sp1.yahoo.com via HTTP; Thu, 27 May 2010 07:49:36 PDT X-Mailer: YahooMailRC/374.4 YahooMailWebService/0.8.103.269680 References: Date: Thu, 27 May 2010 07:49:36 -0700 (PDT) From: Kelly Troyer Subject: Re: [FlyRotary] Re: Rotary HP reviisted....now that I know more about it all...kinda. To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-2048935986-1274971776=:45262" --0-2048935986-1274971776=:45262 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Ed, =0A=C2=A0 In John's case the minimum pitch is 45 degrees.............Th= e "IVO" will not go "Flat" ("O" pitch)=C2=A0=0Abecause of mechanical stops = or go beyond 105 degrees for the same reason............=0AKelly Troyer=0A"= Dyke Delta"_13B ROTARY Engine=0A"RWS"_RD1C/EC2/EM2=0A"Mistral"_Backplate/Oi= l Manifold =0A=0A=0A=0A=0A________________________________=0AFrom: Ed Ander= son =0ATo: Rotary motors in aircraft =0ASent: Thu, May 27, 2010 9:31:11 AM=0ASubject: [FlyRota= ry] Re: Rotary HP reviisted....now that I know more about it all...kinda.= =0A=0A=0AGood point, John=0A=C2=A0=0ANothing like personal experience.=C2= =A0 I failed to take into consideration that the =E2=80=9Cminimum=E2=80=9D = pitch setting of the IVO prop may/could be optimum.=C2=A0 However, I would = not bet my life on it.=C2=A0 I don=E2=80=99t know the IVO prop, but it coul= d be that you can =E2=80=9Cset=E2=80=9D the minimum pitch limit such that y= ou will always generate sufficient thrust =E2=80=93 but you want to convinc= e yourself that your prop =E2=80=9CMinimum=E2=80=9D setting will provide su= fficient thrust for good take off performance.=C2=A0 Also the 70 kt marker = that John mentions is another method to check your thrust/acceleration.=C2= =A0 There no doubt many ways to make this check, just do one or more of the= m before flight.=0A=C2=A0=0AAlso David makes a good point, if you have the = =E2=80=9Cconstant speed=E2=80=9D module then the prop controller will autom= atically compensate for prop load.=C2=A0 But, again, I think you want to ch= eck that Minimum pitch condition.=0A=C2=A0=0AEd=0A=C2=A0=0AEd Anderson=0ARv= -6A N494BW Rotary Powered=0AMatthews, NC=0Aeanderson@carolina.rr.com=0Ahttp= ://www.andersonee.com=0Ahttp://www.dmack.net/mazda/index.html=0Ahttp://www.= flyrotary.com/=0Ahttp://members.cox.net/rogersda/rotary/configs.htm#N494BW= =0Ahttp://www.rotaryaviation.com/Rotorhead%20Truth.htm=0A=0A_______________= _________________=0A=0AFrom:Rotary motors in aircraft [mailto:flyrotary@lan= caironline.net] On Behalf Of John Slade=0ASent: Thursday, May 27, 2010 9:45= AM=0ATo: Rotary motors in aircraft=0ASubject: [FlyRotary] Re: Rotary HP re= viisted....now that I know more about it all...kinda.=0A=C2=A0=0AHi Ed, Chr= is, =0AThat all makes sense, but I can add something from experience with t= he IVO prop - The minimum pitch setting seems to optimum for take-off power= . When I changed from a big fixed pitch prop to an IVO at minimum pitch the= difference in acceleration was very marked. I have never taken off with th= e pitch at a higher setting than minimum, so I can't attest to the effect, = but if you forget to put the pitch on full fine on the downwind, a go-aroun= d is much less doable. =0A=0ASomething else about the IVO that might help, = Chris, is that when you throttle back on final the airplane will want to sl= ow down quite quickly. This is somewhat unexpected if you're used to a fixe= d pitch prop that tends to make the airplane float on final. The combinatio= n of fine pitch at idle, both rudders and the landing brake make a Cozy (or= Velocity I would think) come down like an elevator. =0A=0AOne way to check= that you have enough power would be to measure how much runway you use to = reach, say, 70kts. If it's more than 2000' I'd say you're under powered. Wi= th a turbo and an IVO the acceleration should feel like a good sports car, = and the increase from 70 kts to flying speed will only take a few seconds.= =0AMy 2c.=0AJohn=0A=0Ato Ed Anderson wrote: =0ANo easy answer =E2=80=93 to = all the nuances of producing power, Chris. =0A=C2=A0=0A200 HP is a possibil= ity depending on lots of factors (like your total induction system set up, = however, I believe that 180 HP is more in line with the likely maximum on t= he older 13B.=C2=A0 The Renesis a bit more/=0A=C2=A0=0AFuel flow is as much= an indication of power as anything short of a dyno and/or extensive aircra= ft performance numbers. =0A=C2=A0=0A=C2=A0RPM (in my opinion) =C2=A0has too= many variables =E2=80=93 like I have a 74x88 prop with a 2.85:1 gearbox = =C2=A0and can turn 6000-6200 rpm static =E2=80=93 does that mean I am makin= g more or less HP than you at 6200 rpm at 35=E2=80=9D Hg.=C2=A0 It all depe= nds on what prop load each of our engines are seeing at that rpm.=C2=A0 Gen= erally as a rough rule of thumb you can figure 10 hp per gallon/hour of fue= l flow.=C2=A0 So it you have a fuel flow of 16 gallon/hour then your engine= could be producing around 160 HP.=C2=A0 18 GPH =3D 180 HP, etc.=C2=A0 Now = your power won=E2=80=99t be more than that, but it could be less.=C2=A0 The= rotary can flow considerably more fuel without making useful power than a = piston engine, but it is a useful rule of thumb.=0A=C2=A0=0AI street ported= my 91 Turbo block myself using a Mazdatrix street port template.=C2=A0 I w= ent through 5 intake designs and several muffler experiments before finding= one that appear to give me the power I wanted.=C2=A0 On a cold morning wit= h OAT < 50F, I can get up to 6200 rpm and 18-20 GPH fuel flow with the 74x8= 8 prop.=C2=A0 So I feel I have my set up just about as good as its going to= get =E2=80=93 short of a forced induction system.=0A=C2=A0=0AWith your pro= p set at max =C2=A0fine pitch, you have reduced the prop load on your engin= e to a minimum =E2=80=93 that permits your rpm to be at a maximum =E2=80=93= but, that does NOT mean you are producing the power and more importantly -= the thrust needed for safe flight.=0A=C2=A0=0A=C2=A0Don=E2=80=99t be misle= ad by rpm.=C2=A0 As an extreme example to make my point, Without a prop (al= most no load) my engine will turn 5500 rpm at idle throttle setting =E2=80= =93 but I am only flowing something like 1.5 =E2=80=93 2 GPH which means pr= oducing something like 15-20 HP even though the rpm without prop is higher = than my static was when I had my old 68x72 with a 2.17:1 gear box.=C2=A0 = =C2=A0So even though the rpm is the same or slightly greater, the engine no= t making any where near the=C2=A0 150-160 HP I made with the prop on at the= same rpm.=C2=A0 Fuel flow is not a perfect indicator but much more useful = than RPM alone in estimating your power particularly with a variable pitch = prop.=0A=C2=A0=0AThis is important, Chris.=C2=A0 Years ago, there was a lon= g EZ builder who had a non-rotary auto engine who unfortunately ended his f= irst flight in a fatal crash into a cactus plant.=C2=A0 He understood the e= lectronics just fine, but did not understand the relationship between rpm a= nd thrust.=C2=A0 He set his adjustable pitch prop for maximum RPM =E2=80=93= which mean minimum prop load, which in his case mean minimum thrust.=C2=A0= He managed to get airborne with this limited thrust, but could not apparen= tly climb out of ground effect with the flight ending on impact with a cact= us. =0A=C2=A0=0A=C2=A0For example, you would get your highest rpm with a pr= op that absolutely no pitch which would produce minimum load on the engine = =E2=80=93 however, I think you would agree there would not be much =E2=80= =9Cpush/Pull=E2=80=9D by such a prop set up.=C2=A0 With a variable pitch pr= op, you need to find the optimum balance between rpm and thrust.=C2=A0 Too = much rpm could indicate too little pitch (and too little thrust), too low r= pm could indicate too much pitch (and too little thrust) =E2=80=93 neither = condition gives you maximum thrust.=C2=A0 =0A=C2=A0=0AThe only way I can th= ink of to find that optimum balance between rpm and thrust is to attach you= r airframe through a scale to an anchor.=C2=A0 Then measure the pull on the= scale at various rpm and prop pitch settings.=C2=A0 This should help you f= ind where combination of engine rpm and prop pitch provides maximum thrust = (at least maximum static thrust =E2=80=93 which is a good start).=C2=A0 Per= haps someone else can offer a better and easier method.=C2=A0 Yes, you shou= ld be able to get a feel during taxi test =E2=80=93 although some folks fro= wn on the idea of high-speed taxi test.=C2=A0 Theoretically you could use a= n accelerometer, some accurate speed measurements the weight of=C2=A0 your = aircraft and calculate the effective HP =E2=80=93 that has been done with a= utomobiles.=0A=C2=A0=0AIn cases were folks are using fixed pitch props=C2= =A0 with parameters similar to those used by others, you can make a compari= son and get a rough feel for engine performance based on RPM.=C2=A0 Unfortu= nately, with a variable pitch prop making such comparisons is more difficul= t and questionable.=C2=A0 Now if you can find someone using the same variab= le pitch prop you are using and compare your rpm and prop settings, that is= certainly something worth checking into.=0A=C2=A0=0AJust continue to ask t= hese kinds of questions and to think about the issues in producing power an= d thrust =E2=80=93 you=E2=80=99ll be ready.=0A=C2=A0=0AEd=0A=C2=A0=0A.=C2= =A0 =0A=C2=A0=0AEd Anderson=0ARv-6A N494BW Rotary Powered=0AMatthews, NC=0A= eanderson@carolina.rr.com=0Ahttp://www.andersonee.com=0Ahttp://www.dmack.ne= t/mazda/index.html=0Ahttp://www.flyrotary.com/=0Ahttp://members.cox.net/rog= ersda/rotary/configs.htm#N494BW=0Ahttp://www.rotaryaviation.com/Rotorhead%2= 0Truth.htm=0A=0A________________________________=0A=0AFrom:Rotary motors in= aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Chris Barber=0A= Sent: Wednesday, May 26, 2010 9:51 PM=0ATo: Rotary motors in aircraft=0ASub= ject: [FlyRotary] Rotary HP reviisted....now that I know more about it all.= ..kinda.=0A=C2=A0=0AI know this must have been discussed, but perhaps more = in passing or in some of Tracy 's literature (now=C2=A0kinda dated, especia= lly with some of the strides he continues to make), but what is the convent= ional wisdom as to rotary horsepower?=C2=A0 I know when I first started loo= king into it, oh many years ago, it seemed the impression I got was that yo= u could pretty easily achieve 200 hp, however, that is now a bit lower.=C2= =A0 Some of the tricks to get the higher HP was mild and medium porting, br= idge, "J" and "P" porting.=C2=A0 Then there was the option of turbo...the o= ne, in combination with a medium street port, I chose.=0A=C2=A0=0AWhat say = Ye?=0A=C2=A0=0AWhen started today, mine was turning about 6200 rpm at 35 MP= (with a 3 lb spring in the wastegate).....it surged forward against the ch= ocks and breaks.=C2=A0=C2=A0IVO prop full fine. Nice feel of power even if = it likes to heat up fast in 90 degree weather like this.=0A=C2=A0=0AAlso, I= think this was discussed before too, when I go=C2=A0WOT my engine=C2=A0dev= elops up to about 6250 rpm, but then drops a couple/few hundred rpm to usua= lly just under 6000....sometimes just above.=C2=A0 Thoughts?=C2=A0 Ed, (per= haps Al)it seems you may have chimed in before.=C2=A0 Regrettably, when I s= earch the=C2=A0archives I tend to get frustrated due to thread drift.=0A=C2= =A0=0AI heard a lot about porting when I was initially investigating all th= is and I chose to use a medium street port.=C2=A0 I let=C2=A0Mazdatrix do t= he work.=C2=A0 That being said, I have read all but nothing on others porti= ng their engines (other than a LOT from PL on P ports).=C2=A0 Since standar= d porting does not reportedly effect reliability, only, potentially low=C2= =A0low idle (I can idle as low as about 1300 rpm when warm smoothly) why is= it not discussed and/or utilized more?=0A=C2=A0=0AJust curious guys/gals.= =C2=A0 Discuss =0A=C2=A0=0AAll the best,=0A=C2=A0=0AChris Barber=0AHoust= on, GSOT=0A=0A________________________________=0A=0AFrom:Rotary motors in a= ircraft [flyrotary@lancaironline.net] on behalf of Ed Anderson [eanderson@c= arolina.rr.com]=0ASent: Wednesday, May 26, 2010 5:15 PM=0ATo: Rotary motors= in aircraft=0ASubject: [FlyRotary] Re: Emailing: 3 view w-10 003, first fl= ight=0AAlways loved the lines of a Tailwind =E2=80=93 in fact, I have the p= lans and license to build a W-10 sitting on my book shelf.=C2=A0 Unfortunat= ely, I doubt I=E2=80=99ll ever get around to it.=0A=C2=A0=0AOk with thermos= tat in the system holding it at 190F =E2=80=93 we really won=E2=80=99t know= how much reserve capacity you have in your cooling system until the power = goes up.=0A=C2=A0=0AI agree with George, 200HP out of an N/A 13B is really = pushing it.=C2=A0 I think 180HP is a more realistic expectation =E2=80=93 b= ut, hey you never know.=C2=A0 It amazing how power goes up when things come= together.=0A=C2=A0=0AEnjoy and fly safe. =0AEd Anderson=0ARv-6A N494BW Rot= ary Powered=0AMatthews, NC=0Aeanderson@carolina.rr.com=0Ahttp://www.anderso= nee.com=0Ahttp://www.dmack.net/mazda/index.html=0Ahttp://www.flyrotary.com/= =0Ahttp://members.cox.net/rogersda/rotary/configs.htm#N494BW=0Ahttp://www.r= otaryaviation.com/Rotorhead%20Truth.htm=0A=0A______________________________= __=0A=0AFrom:Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]= On Behalf Of John=0ASent: Wednesday, May 26, 2010 2:36 PM=0ATo: Rotary mot= ors in aircraft=0ASubject: [FlyRotary] Emailing: 3 view w-10 003, first fli= ght=0A=C2=A0=0AMy most humble thank you to flyrotary and all you fine folks= that have=C2=A0helped bring=C2=A0my project to flight.=C2=A0 Ed and many o= thers whom I won't try to name here because I would miss many.=C2=A0 The pl= ane is a Wittman Tailwind W-10, empty wt. is 981 and it is a tri-gear,=C2= =A0 Wt. is within 6 #'s of similar trikes w/ 0-320 engines.=C2=A0 I have th= e thermostat in the engine because most of the year it is not very hot, if = we get 50 days with the temperature over 70, we have had a hot summer, not = a lot of beach bunny activity.=C2=A0 7-1 I'll be 74 and have realized my dr= eam, now it's all gravy.=C2=A0 Again, thanks guys!!=C2=A0 JohnD=0AYour mess= age is ready to be sent with the following file or link attachments:=0A3 vi= ew w-10 003=0A=C2=A0=0A--=0A=0AHomepage: http://www.flyrotary.com/=0A=0AAr= chive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.ht= ml --0-2048935986-1274971776=:45262 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
=0A
Ed,
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  In John's case = the minimum pitch is 45 degrees.............The "IVO" will not go "Flat" ("= O" pitch) 
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because of mechanical stops or go beyond 105 d= egrees for the same reason............
=0A
 
Kelly Troye= r
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Back= plate/Oil Manifold =0A

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=0A
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=0ATo: Rotary motors in aircraft <= flyrotary@lancaironline.net>
Sen= t: Thu, May 27, 2010 9:31:11 AM
Subject: [FlyRotary] Re: Rotary HP reviisted....now that= I know more about it all...kinda.

=0A=0A=0A
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Good poi= nt, John

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Nothing like personal experience.  I failed to take into c= onsideration that the =E2=80=9Cminimum=E2=80=9D pitch setting of the IVO pr= op may/could be optimum.  However, I would not bet my life on it. = ; I don=E2=80=99t know the IVO prop, but it could be that you can =E2=80=9C= set=E2=80=9D the minimum pitch limit such that you will always generate suf= ficient thrust =E2=80=93 but you want to convince yourself that your prop = =E2=80=9CMinimum=E2=80=9D setting will provide sufficient thrust for good t= ake off performance.  Also the 70 kt marker that John mentions is anot= her method to check your thrust/acceleration.  There no doubt many way= s to make this check, just do one or more of them before flight.

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 =

=0A

Also Davi= d makes a good point, if you have the =E2=80=9Cconstant speed=E2=80=9D modu= le then the prop controller will automatically compensate for prop load.&nb= sp; But, again, I think you want to check that Minimum pitch condition.

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E= d

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&= nbsp;

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Fro= m: Rotary motors= in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of John Slade
Sent: Thursday, May 27, 2010 9:45 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Rotary H= P reviisted....now that I know more about it all...kinda.

= =0A

 

=0A

Hi Ed, Chris,
That all makes sense, but I can add = something from experience with the IVO prop - The minimum pitch setting see= ms to optimum for take-off power. When I changed from a big fixed pitch pro= p to an IVO at minimum pitch the difference in acceleration was very marked= . I have never taken off with the pitch at a higher setting than minimum, s= o I can't attest to the effect, but if you forget to put the pitch on full = fine on the downwind, a go-around is much less doable.

Something el= se about the IVO that might help, Chris, is that when you throttle back on = final the airplane will want to slow down quite quickly. This is somewhat u= nexpected if you're used to a fixed pitch prop that tends to make the airpl= ane float on final. The combination of fine pitch at idle, both rudders and= the landing brake make a Cozy (or Velocity I would think) come down like an elevator.

One way to check that you have enough power= would be to measure how much runway you use to reach, say, 70kts. If it's = more than 2000' I'd say you're under powered. With a turbo and an IVO the a= cceleration should feel like a good sports car, and the increase from 70 kt= s to flying speed will only take a few seconds.
My 2c.
John

to= Ed Anderson wrote:

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No easy answer =E2=80=93 to all the nuances of producin= g power, Chris.

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200 HP is a possibility depending on lots of factors (l= ike your total induction system set up, however, I believe that 180 HP is m= ore in line with the likely maximum on the older 13B.  The Renesis a b= it more/

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Fuel flow is as much an indication of power as anything short o= f a dyno and/or extensive aircraft performance numbers.

= =0A

 =

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 RPM (in my= opinion)  has too many variables =E2=80=93 like I have a 74x88 prop w= ith a 2.85:1 gearbox  and can turn 6000-6200 rpm static =E2=80=93 does= that mean I am making more or less HP than you at 6200 rpm at 35=E2=80=9D = Hg.  It all depends on what prop load each of our engines are seeing a= t that rpm.  Generally as a rough= rule of thumb you can figure 10 hp per gallon/hour of fuel flow= .  So it you have a fuel flow of 16 gallon/hour then your engine could= be producing around 160 HP.  18 GPH =3D 180 HP, etc.  Now your p= ower won=E2=80=99t be more than that, but it could be less.  The rotar= y can flow considerably more fuel without making useful power than a piston= engine, but it is a useful rule of thumb.

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I street ported my 91 Turbo blo= ck myself using a Mazdatrix street port template.  I went through 5 in= take designs and several muffler experiments before finding one that appear= to give me the power I wanted.  On a cold morning with OAT < 50F, = I can get up to 6200 rpm and 18-20 GPH fuel flow with the 74x88 prop. = So I feel I have my set up just about as good as its going to get =E2=80= =93 short of a forced induction system.

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With your prop set at max  fi= ne pitch, you have reduced the prop load on your engine to a minimum =E2=80= =93 that permits your rpm to be at a maximum =E2=80=93 but, that does NOT mean you are producing the p= ower and more importantly - the thrust= needed for safe flight.

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 Don=E2=80=99t be mislead by rpm.=   As an extreme example to make my point, Without a prop (almost no load) my engine will turn 550= 0 rpm at idle throttle setting =E2=80=93 but I am only flowing something li= ke 1.5 =E2=80=93 2 GPH which means producing something like 15-20 HP even t= hough the rpm without prop is higher than my static was when I had my old 6= 8x72 with a 2.17:1 gear box.   So even though the rpm is the same= or slightly greater, the engine not making any where near the  150-16= 0 HP I made with the prop on at the same rpm.  Fuel flow is not a perf= ect indicator but much more useful than RPM alone in estimating your power = particularly with a variable pitch prop.

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This is important, Chris. = Years ago, there was a long EZ builder who had a non-rotary auto engine wh= o unfortunately ended his first flight in a fatal crash into a cactus plant= .  He understood the electronics just fine, but did not understand the= relationship between rpm and thrust.  He set his adjustable pitch pro= p for maximum RPM =E2=80=93= which mean minimum prop load, which in his case mean minimum thr= ust.  He managed to get airborne with this limited thrust, = but could not apparently climb out of ground effect with the flight ending = on impact with a cactus.

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 For example, you would get your highest rp= m with a prop that absolutely no pitch which would produce minimum load on = the engine =E2=80=93 however, I think you would agree there would not be mu= ch =E2=80=9Cpush/Pull=E2=80=9D by such a prop set up.  With a variable= pitch prop, you need to find the optimum balance between rpm and thrust.&n= bsp; Too much rpm could indicate too little pitch (and too little thrust), = too low rpm could indicate too much pitch (and too little thrust) =E2=80=93= neither condition gives you maximum thrust. 

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The only way I can t= hink of to find that optimum balance between rpm and thrust is to attach yo= ur airframe through a scale to an anchor.  Then measure the pull on th= e scale at various rpm and prop pitch settings.  This should help you = find where combination of engine rpm and prop pitch provides maximum thrust= (at least maximum static thrust =E2=80=93 which is a good start).  Pe= rhaps someone else can offer a better and easier method.  Yes, you sho= uld be able to get a feel during taxi test =E2=80=93 although some folks fr= own on the idea of high-speed taxi test.  Theoretically you could use = an accelerometer, some accurate speed measurements the weight of  your= aircraft and calculate the effective HP =E2=80=93 that has been done with = automobiles.

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In cases were folks are using fixed pitch props  with pa= rameters similar to those used by others, you can make a comparison and get= a rough feel for engine performance based on RPM.  Unfortunately, wit= h a variable pitch prop making such comparisons is more difficult and quest= ionable.  Now if you can find someone using the same variable pitch pr= op you are using and compare your rpm and prop settings, that is certainly = something worth checking into.

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Just continue to ask these kinds of questio= ns and to think about the issues in producing power and thrust =E2=80=93 yo= u=E2=80=99ll be ready.

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Ed

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. 

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From: Rotary motors in ai= rcraft [mailto:flyrotary@= lancaironline.net] On Behalf Of Chris Barber
Sent:<= /B> Wednesday, May 26, 2010 9:51 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Rotary HP reviisted....now that I kn= ow more about it all...kinda.

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I know this must have been discussed, but perhaps mo= re in passing or in some of Tracy 's literature (now kinda dated, espe= cially with some of the strides he continues to make), but what is the conv= entional wisdom as to rotary horsepower?  I know when I first started = looking into it, oh many years ago, it seemed the impression I got was that= you could pretty easily achieve 200 hp, however, that is now a bit lower.&= nbsp; Some of the tricks to get the higher HP was mild and medium porting, = bridge, "J" and "P" porting.  Then there was the option of turbo...the= one, in combination with a medium street port, I chose.

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What say = Ye?

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When started today, mine was turning about 6200 rpm at 35 MP (= with a 3 lb spring in the wastegate).....it surged forward against the choc= ks and breaks.  IVO prop full fine. Nice feel of power even if it= likes to heat up fast in 90 degree weather like this.

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Also, I thi= nk this was discussed before too, when I go WOT my engine develop= s up to about 6250 rpm, but then drops a couple/few hundred rpm to usually = just under 6000....sometimes just above.  Thoughts?  Ed, (perhaps= Al)it seems you may have chimed in before.  Regrettably, when I searc= h the archives I tend to get frustrated due to thread drift.

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= I heard a lot about porting when I was initially investigating all this and= I chose to use a medium street port.  I let Mazdatrix do the wor= k.  That being said, I have read all but nothing on others porting the= ir engines (other than a LOT from PL on P ports).  Since standard port= ing does not reportedly effect reliability, only, potentially low low = idle (I can idle as low as about 1300 rpm when warm smoothly) why is it not= discussed and/or utilized more?

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Just curious guys/gals.  Dis= cuss <g>

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All the best,

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Chris Barber

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Houston, GSO= T

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From:<= SPAN style=3D"FONT-FAMILY: Tahoma; FONT-SIZE: 10pt"> Rotary motors in aircr= aft [flyrotary@lancairo= nline.net] on behalf of Ed Anderson [eanderson@carolina.rr.com]
Sent: Wednesday, May 26, 2010 5:15 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Emailing: = 3 view w-10 003, first flight

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Always loved the lines of = a Tailwind =E2=80=93 in fact, I have the plans and license to build a W-10 = sitting on my book shelf.  Unfortunately, I doubt I=E2=80=99ll ever ge= t around to it.

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 <= /SPAN>

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O= k with thermostat in the system holding it at 190F =E2=80=93 we really won= =E2=80=99t know how much reserve capacity you have in your cooling system u= ntil the power goes up.

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I agree with George, 200HP out of an N/A 13B is really pushing it.&nbs= p; I think 180HP is a more realistic expectation =E2=80=93 but, hey you nev= er know.  It amazing how power goes up when things come together.

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Enjoy and fly safe. <= /SPAN>

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Ed = Anderson

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Rv= -6A N494BW Rotary Powered

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Matthews, NC

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eanderson@c= arolina.rr.com

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<= A href=3D"http://www.andersonee.com/" rel=3Dnofollow target=3D_blank>http://www.andersonee.com

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http://www.dmack.net/mazda/= index.html

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http://www.flyrotary.com/

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http://members.cox.net/rog= ersda/rotary/configs.htm#N494BW

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http://www.rotaryaviation.com/Rot= orhead%20Truth.htm

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=0AFrom:<= /FONT> Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of John
Sent: Wednesday, May 26, 2010 2:36 PM
To: Rotary motors in aircraft
= Subject: [FlyRotary] Emaili= ng: 3 view w-10 003, first flight

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My most humble thank you to flyrotary and all you fine fol= ks that have helped bring my project to flight.  Ed and many= others whom I won't try to name here because I would miss many.  The = plane is a Wittman Tailwind W-10, empty wt. is 981 and it is a tri-gear,&nb= sp; Wt. is within 6 #'s of similar trikes w/ 0-320 engines.  I have th= e thermostat in the engine because most of the year it is not very hot, if = we get 50 days with the temperature over 70, we have had a hot summer, not = a lot of beach bunny activity.  7-1 I'll be 74 and have realized my dr= eam, now it's all gravy.  Again, thanks guys!!  JohnD

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