X-Virus-Scanned: clean according to Sophos on Logan.com From: "William Jepson" Received: from mail-ua0-f182.google.com ([209.85.217.182] verified) by logan.com (CommuniGate Pro SMTP 6.2c1) with ESMTPS id 9600839 for flyrotary@lancaironline.net; Thu, 23 Mar 2017 11:47:10 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.217.182; envelope-from=wrjjrs@gmail.com Received: by mail-ua0-f182.google.com with SMTP id u30so96860564uau.0 for ; Thu, 23 Mar 2017 08:47:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=6VMZzSzZYkHAX1K6aYtTOmNIR1UUljmSMN6qsFEHwX8=; b=Byw1HHTZ2ty7lParudbbtSmy/BUP5LK/7ku5Ip5eHm3E3C372Y0O+tK3ztZs02iCaS Nbd7+UeqPYaaR7l9Uqn9clyqP9C7K8YNPxZYAyPymdGKRzpD8mSelbYgwXYl6nKLmRzo 76mE1PwOErPldIUOg6zay2mt1L5To9U0oR2glGyqme2Ps8fUADtmx8v3YcIoPKrh9XlR CVEljkYy2SMOROGCEaczvxcunahuFBXo9t9/gRbFZWdO9tg8+3l07oqOr5ZC8IS4mVRd wie7mVZjM0Hd9ooFaMPnwdFCl8XLXX7PyTTyHI1BIorSYkpkrnuCgzRz7ZZKmAaaalTq 7aPw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=6VMZzSzZYkHAX1K6aYtTOmNIR1UUljmSMN6qsFEHwX8=; b=Zs67jANtwvfwMP3DVWxz5RgT9xF6qcUbbEGhCLFS11ywH1jnS+Y/QctUpjTSsmPRoo gp99ytfO/mhr38/Zx17iZXKxbZHXnrZtZZfjhlBQdlo/8UbejUSFLIVDcoHV7x2Uksjt OGB2f/VOomANBo2GFSdmKumzM32MhXwFx07+75JMPwtD19RJBcRFspiXAlHMwteUbCGg TdAfPL9V2ivxAFJ+1tYZpfNdaviO204HFzekfn4UUxVfRtkgggW+9wLWdisLVcshjqHT J3VPbcpCxzSAM82+yfG1wYLXcUs7OGgYzhONeLFWrYoTH6M7gS5yrzH7Qsp/lt85Jh5Y /3vA== X-Gm-Message-State: AFeK/H2Np7PBHk8Y32ZrIbnPiekGdxRYcSMN+NyxTz65kA1xTePYgxnJIO+Wfdu80BvNy8rYKCkJGa5ZbEF71g== X-Received: by 10.176.17.1 with SMTP id e1mr1331964uab.154.1490284014135; Thu, 23 Mar 2017 08:46:54 -0700 (PDT) MIME-Version: 1.0 Received: by 10.31.44.23 with HTTP; Thu, 23 Mar 2017 08:46:53 -0700 (PDT) Received: by 10.31.44.23 with HTTP; Thu, 23 Mar 2017 08:46:53 -0700 (PDT) In-Reply-To: References: Date: Thu, 23 Mar 2017 08:46:53 -0700 Message-ID: Subject: Re: [FlyRotary] Re: redrive options To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=f403045e3b8646f8c4054b67c958 --f403045e3b8646f8c4054b67c958 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Tracy, Paul had the photos on the newsletter. I don't think there was anything wrong 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 be a problem. I would love to be able to examine the gearbox to be sure of what happened. Since you evidently DIDN'T my guess is they felt what they were 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 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 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 wouldn'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 outside problems. The point of the discussion was not a critique of the parts involved, rather a cautionary tale to keep new rotary engine converting owners 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, > > This is the first I=E2=80=99ve heard of Dave=E2=80=99s gear drive havi= ng a burned > bearing. If Dave is around I=E2=80=99d like to know which bearing and an= y other > relevant information, operating RPM, turbo boost on the engine, etc. If > you have any details Bill, let me know. > > > > Tracy > > > > Sent from Mail for > Windows 10 > > > > *From: *William Jepson > *Sent: *Tuesday, March 21, 2017 8:13 PM > *To: *Rotary motors in aircraft > *Subject: *[FlyRotary] Re: redrive options > > > > 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 > ranges it was possible to incur damage due to second order vibrations tha= t > could be just as damaging. Sorry Charlie, but if you think their work was > an unnecessary 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 totally torched the internal bearings. Regarding the > transmission locked in gear, I wouldn't stand near the plane that was usi= ng > the gearbox regardless of the time he had on it. It was a disaster waitin= g > to happen. Everyone thinks this is easy. You can get away with it for a > while but if you want to use your engine at a significant HP level, for a > cross country flight that you intend to return from in the same plane, yo= u > MUST account for torsional vibration. The math isn't terribly tough nor a= re > the parts a lot heavier, but the close meshing gears and stiff model neve= r > had a problem. They had to properly support the pinion gear, and after th= at > the thing was bullet proof. That can't be said about any of the other > reduction boxes I have seen that are even close to the same weight. The > guys built a beautiful torsional dampener into a rotary e-shaft that work= ed > perfectly with a planetary, it just required too much expensive machining= . > Your comment about in resonance problems being regardless of power level = is > true. Fortunately you can usually transition the specific rpm without a l= ot > 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 problem. Automotive engines are built > pretty well today, but a broken gearbox, or drive belt, or torque > converter, or flex plate, or clutch disk can still spoil your whole day. > > Bill Jepson > > > > On Tue, Mar 21, 2017 at 2:15 PM, Charlie England < > flyrotary@lancaironline.net> wrote: > > Uh, that wasn't me. :-) > > But I've heard the case made that exactly what 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 matter much; stuf= f > 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 Mazda transmission as a reduction drive. > Worked great 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, > > 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 that the e-shaft on the rotary is so stiff. I have been > working with Steve Beckham 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 puls= es > 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 causin= g > the failure. That said Steve and Everett Hatch did a LOT of work to be su= re > their "stiff" model reduction drive placed all the frequencies above the > normal operating range. If you hit one of those frequencies with one of t= he > rubber couplings or the bushing-around-bolt dampers it will fail period. > Most of those systems try 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. Typically the energy in the system is low enough > to pass through that RPM without damage. Usually. But if not planned for > those pulses can be a disaster. > > Bill Jepson > > > > On Tue, Mar 21, 2017 at 10:40 AM, cozygirrrl > wrote: > > > > Rotary torque 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 > opposite, the rotary engine does not have the 4 bangs per prop revolution > of a traditional 4 cylinder aircraft engine which shows as a spiky positi= ve > and negative graph when plotted. > The output of the rotary is always positive torque in nature and > overlapping sinusoidal due to the two rotors when the output wave forms a= re > plotted, hence the smoothness of the rotary. When peak output is plotted = it > shows an always positive gentle wave. > > Chrissi > > CG Products > > www.CozyGirrrl.com > > > > > > > > -----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 > specifically=E2=80=8B mention the rotary. If they know anything they will= be > worried. > > Bill Jepson > > > > On Mar 20, 2017 3:48 PM, "drhyed" wrote: > > I had brief conversation with them last fall and they designed the gearbo= x > with the intention of offering higher horsepower options: > > > > "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 start. > > > Our intent is to do a 155 hp normally aspirated 2 liter and a 200 hp turb= o > version" > > > > I did not mention a rotary engine specifically though. > > > > > > 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 abou= t > whether they are legit, or whether the drive is suitable for a rotary. Th= e > web page claims 'good up to 225HP', but their target installations are > closer to half that, so.... > > > > http://www.aeromomentum.com/partslist.html > > > > Charlie > > > > > > > > > > > --f403045e3b8646f8c4054b67c958 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Tracy,
Paul had the photos on the newsle= tter. I don't think there was anything wrong with the drive. He was jus= t 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 w= as bright blue from what looked like over heat. There is also the possibili= ty that there was an oiling problem completely unrelated to the gearbox tha= t 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 problem. I would love to = be able to examine the gearbox to be sure of what happened. Since you evide= ntly DIDN'T my guess is they felt what they were 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 that was the year the Musta= ng 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.=C2= =A0 I have made clear when ever mentioning the incident that this was racin= g and the loads and forces are very unusual doing so. Having built many car= s for racing I can state things fail in places you wouldn't believe. (A= sk me about the battery cable failure I had on a formula C SCCA car sometim= e.) Also the causes of failures may be unrelated to the soundness of design= on the parts involved, and can be caused by other outside problems. The po= int of the discussion was not a critique of the parts involved, rather a ca= utionary tale to keep new rotary engine converting owners to be aware of th= e need to do careful assembly to prevent problems. Check with P.L. to see i= f he has the pictures of Dave's redrive stored somewhere.

Bill Jep= son

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

Hi Bill,

=C2=A0=C2=A0 Th= is is the first I=E2=80=99ve heard of Dave=E2=80=99s gear drive having a bu= rned bearing.=C2=A0 If Dave is around I=E2=80=99d like to know which bearin= g and any other relevant information, operating RPM, turbo boost on the eng= ine, 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: = Willia= m Jepson
Sent: Tuesday, March 21, 2017 8:13 PM
To: = Rotary mot= ors in aircraft
Subject: [FlyRotary] Re: redrive options

<= /div>

=C2=A0

Charlie,

No they build a complete gearb= ox using planetary gears first. (spur only so no end thrust) They found as = you ran the engine through various speed ranges it was possible to incur da= mage due to second order vibrations that could be just as damaging. Sorry C= harlie, but if you think their work was an unnecessary rabbit hole I won= 9;t be flying in your plane. That isn't intended to be insulting. I jus= t have seen the results of not handling these forces. Dave Lenard flew his = RV-6 behind Tracy's gearbox at Reno qualifying and totally torched the = internal bearings. Regarding the transmission locked in gear, 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 thinks this is ea= sy. You can get away with it for a while but if you want to use your engine= at a significant HP level, for a cross country flight that you intend to r= eturn from in the same plane, you MUST account for torsional vibration. The= math isn't terribly tough nor are the parts a lot heavier, but the clo= se 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 ca= n't be said about any of the other reduction boxes I have seen that are= even close to the same weight. The guys built a beautiful torsional dampen= er into a rotary e-shaft that worked perfectly with a planetary, it just re= quired too much expensive machining. Your comment about in resonance proble= ms being regardless of power level is true. Fortunately you can usually tra= nsition 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 thin= king 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 problem.= Automotive engines are built pretty well today, but a broken gearbox, or d= rive belt, or torque converter, or flex plate, or clutch disk can still spo= il your whole day.

Bill Jepson

=C2=A0

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

Uh, that wasn't me. :-)

B= ut I've heard the case made that exactly what you describe is what happ= ened (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 th= at *in resonance*, power level doesn't really matter much; stuff is goi= ng 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 & rp= m where their failure occurred. Doesn't it make you wonder if the resul= ts would have been the same?

One of our former members (since deceas= ed due to natural causes) flew successfully for years using a Mazda transmi= ssion as a reduction drive. Worked great until one day when the engine star= ted on only one rotor (1per-rev) & *at idle power* it destroyed the gea= rbox.

I can't help but wonder if that dyno incident took them do= wn an unnecessary rabbit hole of expensive zero-clearance gears & 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 ter= ms of torsional vibration though the rotary is a tough customer. Part of th= e problem is that the e-shaft on the rotary is so stiff. I have been workin= g with Steve Beckham 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 u= sed to test 600+ HP V8 piston engines. This is the torque pulses of the eng= ine, not out-of-balance. It is likely that in that case the rotary hit a am= plifying couple or harmonic frequency with the dyno causing the failure. Th= at said Steve and Everett Hatch did a LOT of work to be sure their "st= iff" model reduction drive placed all the frequencies above the normal= operating range. If you hit one of those frequencies with one of the rubbe= r couplings or the bushing-around-bolt dampers it will fail period. Most of= those systems try to push the first order frequency below the operating ra= nge. That is why you will often hear the engine shut down rattle with a pla= netary. Typically the energy in the system is low enough to pass through th= at RPM without damage. Usually. But if not planned for those pulses can be = a disaster.

Bill Jepson

=C2=A0

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

=C2=A0

=C2=A0<= u>

-----Original Message-----
From: William Jepson <flyrotary@la= ncaironline.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.= net>
Sent: Mon, Mar 20, 2017 7:02 pm
Subject: [FlyRotary] Re: = redrive options

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

Bill Jepson

=C2=A0

On Mar 20, 2017 3:48 PM, "drhyed" <flyrotary@lancaironline= .net> wrote:

I had= brief conversation with them last fall and they designed the gearbox with = the intention of offering higher horsepower options:

=C2=A0<= /p>

"We do have plans for = a higher horsepower engine.=C2=A0 When we designed our gearbox we intended = to do engines to about 225 hp from the start.


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

=C2=A0<= /p>

I did not mention a rotary = engine specifically though.

=C2=A0

=C2=A0

Jay


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

<= div>

These guys have been advertising= on ebay for a while. I have no idea about whether they are legit, or wheth= er 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....<= u>

=C2= =A0

=C2=A0

<= div>

Charlie

=C2=A0

=C2=A0<= u>

=C2=A0

= =C2=A0

=C2=A0

--f403045e3b8646f8c4054b67c958--