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(h224.112.131.174.dynamic.ip.windstream.net. [174.131.112.224]) by smtp.gmail.com with ESMTPSA id s28sm3543569qts.65.2017.03.23.09.34.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 23 Mar 2017 09:34:55 -0700 (PDT) Message-ID: <58d3f92f.9c24c80a.fd25a.3dcf@mx.google.com> MIME-Version: 1.0 To: "Bobby J. Hughes" Subject: RE: [FlyRotary] Re: redrive options Date: Thu, 23 Mar 2017 12:34:53 -0400 Importance: normal X-Priority: 3 In-Reply-To: References: Content-Type: multipart/alternative; boundary="_2A8E0DD6-89B7-4713-99F0-73379BF82B04_" --_2A8E0DD6-89B7-4713-99F0-73379BF82B04_ Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Thanks for the info Bill. Sounds like it was the input shaft thrust bearin= g that went out. That is without question the most highly stressed bearing= in the drive. All the others have easy jobs by comparison. That bearing = requires the cooling of the oil flow via a very small passage through the i= nput shaft. That=E2=80=99s why full oil pressure to the drive is important= . Now that you mention it I do recall Dave asking about the effects of =E2=80= =98T=E2=80=99ing the turbo oil supply on the same line as the drive. That = could potentially drop the pressure too much, especially on -4 lines which = the drive calls for. Tracy Sent from Mail for Windows 10 From: Bobby J. Hughes Sent: Thursday, March 23, 2017 12:13 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: redrive options IFRC the gearbox oil feed was shared with the turbo and had been operated t= hat way for several hundred hours prior to Reno. I think Dave posted the in= formation but I don=E2=80=99t see it in the archives. Hopefully Dave will c= hime in.=20 Bobby From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]=20 Sent: Thursday, March 23, 2017 11:47 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: redrive options Tracy, Paul had the photos on the newsletter. I don't think there was anything wro= ng with the drive. He was just way outside normal HP and load. Turbo 13B in= his RV-6. The bearing at the rear of the output shaft, not sure if it was = a thrust bearing or support, looked siezed. There was considerable amounts = of swarf and the outer ring was bright blue from what looked like over heat= . There is also the possibility that there was an oiling problem completely= unrelated to the gearbox that caused the failure. Since the planes are at = high revs and pulling some g-load on the course all the time oiling could b= e a problem. I would love to be able to examine the gearbox to be sure of w= hat happened. Since you evidently DIDN'T my guess is they felt what they we= re doing was abusive and caused the failure. They got another redrive from = someone else and changed it out that night. Dave never got to race it as th= at was the year the Mustang broke and went into the crowd. Dave was a milit= ary doctor and was quite heroic doing lifesaving work on many of the surviv= ors of the accident.=C2=A0 I have made clear when ever mentioning the incid= ent that this was racing and the loads and forces are very unusual doing so= . Having built many cars for racing I can state things fail in places you w= ouldn't believe. (Ask me about the battery cable failure I had on a formula= C SCCA car sometime.) Also the causes of failures may be unrelated to the = soundness of design on the parts involved, and can be caused by other outsi= de problems. The point of the discussion was not a critique of the parts in= volved, rather a cautionary tale to keep new rotary engine converting owner= s to be aware of the need to do careful assembly to prevent problems. Check= with P.L. to see if he has the pictures of Dave's redrive stored somewhere= . Bill Jepson On Mar 23, 2017 4:16 AM, "rwstracy" wrote: Hi Bill, =C2=A0=C2=A0 This is the first I=E2=80=99ve heard of Dave=E2=80=99s gear dr= ive having a burned bearing.=C2=A0 If Dave is around I=E2=80=99d like to kn= ow which bearing and any other relevant information, operating RPM, turbo b= oost on the engine, etc.=C2=A0 If you have any details Bill, let me know. =C2=A0 Tracy =C2=A0 Sent from Mail for Windows 10 =C2=A0 From: William Jepson Sent: Tuesday, March 21, 2017 8:13 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: redrive options =C2=A0 Charlie, No they build a complete gearbox using planetary gears first. (spur only so= no end thrust) They found as you ran the engine through various speed rang= es it was possible to incur damage due to second order vibrations that coul= d be just as damaging. Sorry Charlie, but if you think their work was an un= necessary rabbit hole I won't be flying in your plane. That isn't intended = to be insulting. I just have seen the results of not handling these forces.= Dave Lenard flew his RV-6 behind Tracy's gearbox at Reno qualifying and to= tally torched the internal bearings. Regarding the transmission locked in g= ear, I wouldn't stand near the plane that was using the gearbox regardless = of the time he had on it. It was a disaster waiting to happen. Everyone thi= nks this is easy. You can get away with it for a while but if you want to u= se your engine at a significant HP level, for a cross country flight that y= ou intend to return from in the same plane, you MUST account for torsional = vibration. The math isn't terribly tough nor are the parts a lot heavier, b= ut the close meshing gears and stiff model never had a problem. They had to= properly support the pinion gear, and after that the thing was bullet proo= f. That can't be said about any of the other reduction boxes I have seen th= at are even close to the same weight. The guys built a beautiful torsional = dampener into a rotary e-shaft that worked perfectly with a planetary, it j= ust required too much expensive machining. Your comment about in resonance = problems being regardless of power level is true. Fortunately you can usual= ly transition the specific rpm without a lot of damage, but if you spend an= y time there even at idle you are going to break parts. I am tired of peopl= e thinking an auto conversion is too easy and then dead sticking their plan= e in a field somewhere. (As a best case) The base engines are rarely the pr= oblem. Automotive engines are built pretty well today, but a broken gearbox= , or drive belt, or torque converter, or flex plate, or clutch disk can sti= ll spoil your whole day. Bill Jepson =C2=A0 On Tue, Mar 21, 2017 at 2:15 PM, Charlie England wrote: Uh, that wasn't me. :-) But I've heard the case made that exactly what you describe is what happene= d (dyno designed for V-8s at 4per-rev; twice the excitation frequency). I d= idn't stay in a Holiday Inn last night, but those who did tell me that *in = resonance*, power level doesn't really matter much; stuff is going to break= . I'd love to see that same driveshaft & dyno hooked to something like a bi= g 4cyl engine (2per-rev) capable of the same HP & rpm where their failure o= ccurred. Doesn't it make you wonder if the results would have been the same= ? One of our former members (since deceased due to natural causes) flew succe= ssfully for years using a Mazda transmission as a reduction drive. Worked g= reat until one day when the engine started on only one rotor (1per-rev) & *= at idle power* it destroyed the gearbox. I can't help but wonder if that dyno incident took them down an unnecessary= rabbit hole of expensive zero-clearance gears & extra weight. Charlie On 3/21/2017 3:51 PM, William Jepson wrote: Charlie,=20 In terms of simple vibration caused by out of balance you are correct. It t= erms of torsional vibration though the rotary is a tough customer. Part of = the problem is that the e-shaft on the rotary is so stiff. I have been work= ing with Steve Beckham from the original PowerSport. Steve told me about ho= w a 200 HP rotary just blew up the input shaft on a dyno that was regularly= used to test 600+ HP V8 piston engines. This is the torque pulses of the e= ngine, not out-of-balance. It is likely that in that case the rotary hit a = amplifying couple or harmonic frequency with the dyno causing the failure. = That said Steve and Everett Hatch did a LOT of work to be sure their "stiff= " model reduction drive placed all the frequencies above the normal operati= ng range. If you hit one of those frequencies with one of the rubber coupli= ngs or the bushing-around-bolt dampers it will fail period. Most of those s= ystems try to push the first order frequency below the operating range. Tha= t is why you will often hear the engine shut down rattle with a planetary. = Typically the energy in the system is low enough to pass through that RPM w= ithout damage. Usually. But if not planned for those pulses can be a disast= er. Bill Jepson =C2=A0 On Tue, Mar 21, 2017 at 10:40 AM, cozygirrrl = wrote: =C2=A0 Rotary torque pulses can be very destructive before buying anything specifi= cally=E2=80=8B mention the rotary. If they know anything they will be worri= ed. Bill Jepson =C2=A0 Somebody please correct me if I am wrong but I have understood the opposite= , the rotary engine does not have the 4 bangs per prop revolution of a trad= itional 4 cylinder aircraft engine which shows as a spiky positive and nega= tive graph when plotted.=20 The output of the rotary is always positive torque in nature and overlappin= g sinusoidal due to the two rotors when the output wave forms are plotted, = hence the smoothness of the rotary. When peak output is plotted it shows an= always positive gentle wave. Chrissi=20 CG Products=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=20 www.CozyGirrrl.com=20 =C2=A0 =C2=A0 =C2=A0 -----Original Message----- From: William Jepson To: Rotary motors in aircraft Sent: Mon, Mar 20, 2017 7:02 pm Subject: [FlyRotary] Re: redrive options Rotary torque pulses can be very destructive before buying anything specifi= cally=E2=80=8B mention the rotary. If they know anything they will be worri= ed. Bill Jepson =C2=A0 On Mar 20, 2017 3:48 PM, "drhyed" wrote: I had brief conversation with them last fall and they designed the gearbox = with the intention of offering higher horsepower options: =C2=A0 "We do have plans for a higher horsepower engine.=C2=A0 When we designed ou= r gearbox we intended to do engines to about 225 hp from the start. Our intent is to do a 155 hp normally aspirated 2 liter and a 200 hp turbo = version" =C2=A0 I did not mention a rotary engine specifically though. =C2=A0 =C2=A0 Jay On Mar 20, 2017, at 5:31 PM, Charlie England = wrote: These guys have been advertising on ebay for a while. I have no idea about = whether they are legit, or whether the drive is suitable for a rotary. The = web page claims 'good up to 225HP', but their target installations are clos= er to half that, so.... =C2=A0 http://www.aeromomentum.com/partslist.html =C2=A0 Charlie =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 --_2A8E0DD6-89B7-4713-99F0-73379BF82B04_ Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="utf-8"

Thanks for the info Bill.=C2=A0 Soun= ds like it was the input shaft thrust bearing that went out.=C2=A0 That is = without question the most highly stressed bearing in the drive.=C2=A0 All t= he others have easy jobs by comparison.=C2=A0 That bearing requires the coo= ling of the oil flow via a very small passage through the input shaft.=C2= =A0 That=E2=80=99s why full oil pressure to the drive is important.

 

Now that you men= tion it I do recall Dave asking about the effects of =E2=80=98T=E2=80=99ing= the turbo oil supply on the same line as the drive.=C2=A0 That could poten= tially drop the pressure too much, especially on -4 lines which the drive c= alls for.

 

Tracy

 

Se= nt from Mail for Windows 10

 

 

IFRC the gearbox oil feed was shared with the turbo and had been oper= ated that way for several hundred hours prior to Reno. I think Dave posted = the information but I don=E2=80=99t see it in the archives. Hopefully Dave = will chime in.

 

Bobby

 

 

=  

Fro= m: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
S= ent: Thursday, March 23, 2017 11:47 AM
To: Rotary motors in a= ircraft
Subject: [FlyRotary] Re: redrive options

 

Tracy,

Paul had t= he photos on the newsletter. I don't think there was anything wrong with th= e drive. He was just way outside normal HP and load. Turbo 13B in his RV-6.= The bearing at the rear of the output shaft, not sure if it was a thrust b= earing or support, looked siezed. There was considerable amounts of swarf a= nd the outer ring was bright blue from what looked like over heat. There is= also the possibility that there was an oiling problem completely unrelated= to the gearbox that caused the failure. Since the planes are at high revs = and pulling some g-load on the course all the time oiling could be a proble= m. I would love to be able to examine the gearbox to be sure of what happen= ed. Since you evidently DIDN'T my guess is they felt what they were doing w= as abusive and caused the failure. They got another redrive from someone el= se and changed it out that night. Dave never got to race it as that was the= year the Mustang broke and went into the crowd. Dave was a military doctor= and was quite heroic doing lifesaving work on many of the survivors of the= accident.  I have made clear when ever mentioning the incident that t= his was racing and the loads and forces are very unusual doing so. Having b= uilt many cars for racing I can state things fail in places you wouldn't be= lieve. (Ask me about the battery cable failure I had on a formula C SCCA ca= r sometime.) Also the causes of failures may be unrelated to the soundness = of design on the parts involved, and can be caused by other outside problem= s. The point of the discussion was not a critique of the parts involved, ra= ther a cautionary tale to keep new rotary engine converting owners to be aw= are of the need to do careful assembly to prevent problems. Check with P.L.= to see if he has the pictures of Dave's redrive stored somewhere.

 

On Mar 23,= 2017 4:16 AM, "rwstracy" <flyrotary@lancaironline.net> wrote:

Hi Bi= ll,

 

Tracy

 

Sent from Mail for = Windows 10

 

From: William Jepson
Sent: Tuesday, March = 21, 2017 8:13 PM
To: Rotary motors in aircraft
Subject: [FlyR= otary] Re: redrive options

 

Charlie,<= /span>

N= o they build a complete gearbox using planetary gears first. (spur only so = no end thrust) They found as you ran the engine through various speed range= s it was possible to incur damage due to second order vibrations that could= be just as damaging. Sorry Charlie, but if you think their work was an unn= ecessary rabbit hole I won't be flying in your plane. That isn't intended t= o be insulting. I just have seen the results of not handling these forces. = Dave Lenard flew his RV-6 behind Tracy's gearbox at Reno qualifying and tot= ally torched the internal bearings. Regarding the transmission locked in ge= ar, I wouldn't stand near the plane that was using the gearbox regardless o= f the time he had on it. It was a disaster waiting to happen. Everyone thin= ks this is easy. You can get away with it for a while but if you want to us= e your engine at a significant HP level, for a cross country flight that yo= u intend to return from in the same plane, you MUST account for torsional v= ibration. The math isn't terribly tough nor are the parts a lot heavier, bu= t the close meshing gears and stiff model never had a problem. They had to = properly support the pinion gear, and after that the thing was bullet proof= . That can't be said about any of the other reduction boxes I have seen tha= t are even close to the same weight. The guys built a beautiful torsional d= ampener into a rotary e-shaft that worked perfectly with a planetary, it ju= st required too much expensive machining. Your comment about in resonance p= roblems being regardless of power level is true. Fortunately you can usuall= y transition the specific rpm without a lot of damage, but if you spend any= time there even at idle you are going to break parts. I am tired of people= thinking an auto conversion is too easy and then dead sticking their plane= in a field somewhere. (As a best case) The base engines are rarely the pro= blem. Automotive engines are built pretty well today, but a broken gearbox,= or drive belt, or torque converter, or flex plate, or clutch disk can stil= l spoil your whole day.

Bill Jepson

<= /div>

=  

On Tue, Mar 21, 2017 at 2:15 PM, Charlie England <flyrotary@lanca= ironline.net> wrote:

= Uh, that wasn't me. :-)

But I've heard the case made that exactly wh= at you describe is what happened (dyno designed for V-8s at 4per-rev; twice= the excitation frequency). I didn't stay in a Holiday Inn last night, but = those who did tell me that *in resonance*, power level doesn't really matte= r much; stuff is going to break. I'd love to see that same driveshaft &= dyno hooked to something like a big 4cyl engine (2per-rev) capable of the = same HP & rpm where their failure occurred. Doesn't it make you wonder = if the results would have been the same?

One of our former members (= since deceased due to natural causes) flew successfully for years using a M= azda transmission as a reduction drive. Worked great until one day when the= engine started on only one rotor (1per-rev) & *at idle power* it destr= oyed the gearbox.

I can't help but wonder if that dyno incident took= them down an unnecessary rabbit hole of expensive zero-clearance gears &am= p; extra weight.

Charlie

=

On 3/21/2017 3:51 PM, William Jepson wrote:

Charlie,

In terms of simple= vibration caused by out of balance you are correct. It terms of torsional = vibration though the rotary is a tough customer. Part of the problem is tha= t the e-shaft on the rotary is so stiff. I have been working with Steve Bec= kham from the original PowerSport. Steve told me about how a 200 HP rotary = just blew up the input shaft on a dyno that was regularly used to test 600+= HP V8 piston engines. This is the torque pulses of the engine, not out-of-= balance. It is likely that in that case the rotary hit a amplifying couple = or harmonic frequency with the dyno causing the failure. That said Steve an= d Everett Hatch did a LOT of work to be sure their "stiff" model = reduction drive placed all the frequencies above the normal operating range= . If you hit one of those frequencies with one of the rubber couplings or t= he bushing-around-bolt dampers it will fail period. Most of those systems t= ry to push the first order frequency below the operating range. That is why= you will often hear the engine shut down rattle with a planetary. Typicall= y the energy in the system is low enough to pass through that RPM without d= amage. Usually. But if not planned for those pulses can be a disaster.=

Bill Jepson

On Tue, Mar 21, 2017 at 10:40 = AM, cozygirrrl <flyrotary@lancaironline.net> wrote:

 

Rotary tor= que pulses can be very destructive before buying anything specifically=E2= =80=8B mention the rotary. If they know anything they will be worried.

Bill Jepson

=

 

= Somebody please correct me if I am wrong but I have understood the opposit= e, the rotary engine does not have the 4 bangs per prop revolution of a tra= ditional 4 cylinder aircraft engine which shows as a spiky positive and neg= ative graph when plotted.
The output of the rotary is always positive t= orque in nature and overlapping sinusoidal due to the two rotors when the o= utput wave forms are plotted, hence the smoothness of the rotary. When peak= output is plotted it shows an always positive gentle wave.

Chrissi

= CG Products      

&n= bsp;<= /span>

 = ;

 

-----Original Message-----
From: William Jepson <flyrotary@lancai= ronline.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net<= /a>>
Sent: Mon, Mar 20, 2017 7:02 pm
Subject: [FlyRotary] Re: redr= ive options=

 

On Mar 20, 2017 3:48 PM, "drhyed" <flyrotary@lancair= online.net> wrote:I had brief conversation with them last fall and they designed th= e gearbox with the intention of offering higher horsepower options:<= span style=3D'font-family:"Times New Roman",serif'>

 

"We do have plans for a higher horsepower engine.  When we= designed our gearbox we intended to do engines to about 225 hp from the st= art.<= /span>


Our intent is to do a 155 hp n= ormally aspirated 2 liter and a 200 hp turbo version"

=

 

I= did not mention a rotary engine specifically though.

 

 <= /span>

Jay

<= br>On Mar 20, 2017, at 5:31 PM, Charlie England <flyrotary@lancaironline.net&g= t; wrote:

These guys have been advertising o= n ebay for a while. I have no idea about whether they are legit, or whether= the drive is suitable for a rotary. The web page claims 'good up to 225HP'= , but their target installations are closer to half that, so....

=

 

<= span style=3D'font-size:10.0pt;font-family:"Arial",sans-serif;color:black'>= ht= tp://www.aeromomentum.com/partslist.html

 Charlie=

<= /div>

 

 

 =

<= span style=3D'font-family:"Times New Roman",serif'> =

 

 

= --_2A8E0DD6-89B7-4713-99F0-73379BF82B04_--