X-Virus-Scanned: clean according to Sophos on Logan.com From: "Charlie England" Received: from mail-pg0-f50.google.com ([74.125.83.50] verified) by logan.com (CommuniGate Pro SMTP 6.2c1) with ESMTPS id 9596159 for flyrotary@lancaironline.net; Wed, 22 Mar 2017 09:21:17 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.83.50; envelope-from=ceengland7@gmail.com Received: by mail-pg0-f50.google.com with SMTP id 21so75299885pgg.1 for ; Wed, 22 Mar 2017 06:21:17 -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=gmZ/LO664KoVpKPQk3X5GxrOg3WmSbUKFaE9cXGGMQg=; b=myfPfHN3nmSu3/Ledvr39A1dRdDxvJ3LwEUyMObwa1VXyt2PkSCz3To4XN97ITX3on Ez2OseNh4ZitDBnOdDsZr8dL+5ib0O4Z/KGKtFdiPYXD5F6H6eMuqsUU+K4GL6WdRor0 M4x+vLAkbaC/FMM1AlD23CjTxfqb1tULIu3NloQYWN5uNzRDuFX0Zo+NRywRo0+TzX0W bR5P1+eGVTykRUyK/g1Ptn288nSHz8zg/7PkFmAXnU3r2LzSjeQY04KXO89pxQ/ZJ03i fAPKDYGEXBL5PRz8LBORl7fcdeNA2Ngmv09orTl7ztsRtLUeLx4AtQAiAICQrYH66Fwe cN+A== 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=gmZ/LO664KoVpKPQk3X5GxrOg3WmSbUKFaE9cXGGMQg=; b=PEpytRL9xdOEX4Nkp5Rt426fEWWA7WJmsChc5z0CdksS0dOOl2Nt1FqLJ+XAciRAhp 0gxQ+z6F5JJjTH4AygfyzF0Ta6tS+j7kXLtM4J/uzjb35ZuwUbChJbCjA2Udv2Keb8R8 v6xqamd8tdP8eUS8JsIlgYFTp/BoXl8zA/x2Gu1SmrF0YSF114aBG6uunz5HuW33LCB7 yeeiZ9A/CdDX29klXW2J9EndXq8iZ36AgjOLQoF3787b8+orRc1iSXXBwF3O0+4CxHHr fReE1ryRROTY1e1Ill1jGp8yO1Z74TXjLITpDK8sjrncaup8Le3MUZhj4yhpfGgcS60S YGAA== X-Gm-Message-State: AFeK/H1ERDYkqp6jj7qZSUMu2fe+KlTdgQ3rvtl25sDax7cbk+LTKtf+tzPCvRjNBt75EeTGGN0+U0D+/NJQUw== X-Received: by 10.84.231.193 with SMTP id g1mr42735783pln.1.1490188859030; Wed, 22 Mar 2017 06:20:59 -0700 (PDT) MIME-Version: 1.0 Received: by 10.100.128.83 with HTTP; Wed, 22 Mar 2017 06:20:58 -0700 (PDT) In-Reply-To: References: Date: Wed, 22 Mar 2017 08:20:58 -0500 Message-ID: Subject: Re: [FlyRotary] Re: redrive options To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=f403045fdd9697420f054b51a137 --f403045fdd9697420f054b51a137 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable I'm sorry if I gave the impression that their work wasn't valuable. It was, I'm glad it was done, and I hate that the drive 'disappeared' for so long. I'm glad it's being revived, too. And I agree that designing/building a safe, reliable gearbox is by far the toughest thing to do to make *any* alternative engine work on an a/c. But to say that a 'soft' system won't work with a rotary simply because *they* didn't get it to work flies in the face of what engineers tell us, and also in the face of empirical evidence. I don't doubt that they had all the problems you describe. But designing around *every conceivable* configuration & condition is pretty difficult, and often, not required. The trick is to know where the issues lie, and be sure that they're avoided in operation. You mention Dave Leonard torching RWS bearings, but fail to mention the torched bearings in the Powersport time to climb attempt at Sun N Fun a couple of decades ago. I don't consider either incident relevant to the discussion, since both were outside of normal operating parameters and neither involved torsional resonance issues. Throwing out such examples just muddy the waters of legitimate research. (BTW, I don't want to fly a car transmission, either, but the point is, it worked for hundreds of hours without any problems until one day it got operated in a condition far outside normal conditions.) Consider the certified world. Many (most?) certified aluminum constant speed props on certified a/c engines (hundreds of thousands in operation for decades) have placarded yellow arcs on the tach where the engine cannot be operated continuously, and they're there because of resonance issues. The Sensenich fixed pitch aluminum prop for 160 HP Lycs on RV-x's (thousands in operation) is placarded against operation above 2600 rpm, also due to *high frequency* resonance issues (engine is designed to operate at 2700 rpm continuously for 75% power at altitude). All have been demonstrated to fail if operated incorrectly, but because they're operated in compliance with posted restrictions they're safe. The Powersport research was a for-profit operation, so for good reason (for them), the full body of research has, to my knowledge, never been published. If it was published, we might see any number of factors that show their earlier designs could be operated safely by simply avoiding continuous operation at resonance points, or avoiding the use of heavy metal props, or changing the compliance of the soft coupler, or adding mass to the flywheel, or...etc etc. Charlie On Tue, Mar 21, 2017 at 7:13 PM, William Jepson wrote: > 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; stu= ff >> 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. I= t >> 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 wa= s >> regularly used to test 600+ HP V8 piston engines. This is the torque pul= ses >> 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 causi= ng >> the failure. That said Steve and Everett Hatch did a LOT of work to be s= ure >> 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 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 enoug= h >> 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 wi= ll 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 revoluti= on >>> of a traditional 4 cylinder aircraft engine which shows as a spiky posi= tive >>> 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= are >>> plotted, hence the smoothness of the rotary. When peak output is plotte= d 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 wi= ll 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 >>> gearbox 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 >>> turbo version" >>> >>> I did not mention a rotary engine specifically though. >>> >>> >>> Jay >>> >>> On Mar 20, 2017, at 5:31 PM, Charlie England < >>> flyrotary@lancaironline.net> 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 closer to half that, so.... >>> >>> http://www.aeromomentum.com/partslist.html >>> >>> Charlie >>> >>> >> >> > --f403045fdd9697420f054b51a137 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
I'm sorry if I gave the impression that their work was= n't valuable. It was, I'm glad it was done, and I hate that the dri= ve 'disappeared' for so long. I'm glad it's being revived, = too. And I agree that designing/building a safe, reliable gearbox is by far= the toughest thing to do to make *any* alternative engine work on an a/c.<= div>
But to say that a 'soft' system won't work w= ith a rotary simply because *they* didn't get it to work flies in the f= ace of what engineers tell us, and also in the face of empirical evidence. = I don't doubt that they had all the problems you describe. But designin= g around *every conceivable* configuration =C2=A0& condition is pretty = difficult, and often, not required. The trick is to know where the issues l= ie, and be sure that they're avoided in operation.=C2=A0

=
You mention Dave Leonard torching RWS bearings, but fail to ment= ion the torched bearings in the Powersport time to climb attempt at Sun N F= un a couple of decades ago. I don't consider either incident relevant t= o the discussion, since both were outside of normal operating parameters an= d neither involved torsional resonance issues. Throwing out such examples j= ust muddy the waters of legitimate research. (BTW, I don't want to fly = a car transmission, either, but the point is, it worked for hundreds of hou= rs without any problems until one day it got operated in a condition far ou= tside normal conditions.)

Consider the certified w= orld. Many (most?) certified aluminum constant speed props on certified a/c= engines (hundreds of thousands in operation for decades) have placarded ye= llow arcs on the tach where the engine cannot be operated continuously, and= they're there because of resonance issues. The Sensenich fixed pitch a= luminum prop for 160 HP Lycs on RV-x's (thousands in operation) is plac= arded against operation above 2600 rpm, also due to *high frequency* resona= nce issues (engine is designed to operate at 2700 rpm continuously for 75% = power at altitude). All have been demonstrated to fail if operated incorrec= tly, but because they're operated in compliance with posted restriction= s they're safe.

The Powersport research was a = for-profit operation, so for good reason (for them), the full body of resea= rch has, to my knowledge, never been published. If it was published, we mig= ht see any number of factors that show their earlier designs could be opera= ted safely by simply avoiding continuous operation at resonance points, or = avoiding the use of heavy metal props, or changing the compliance of the so= ft coupler, or adding mass to the flywheel, or...etc etc.

Charlie



On Tue, Mar 21, 2017 at 7:13 PM, Wi= lliam Jepson <flyrotary@lancaironline.net> wrote:<= br>
Charlie,
No they bui= ld a complete gearbox using planetary gears first. (spur only so no end thr= ust) They found as you ran the engine through various speed ranges it was p= ossible to incur damage due to second order vibrations that could be just a= s damaging. Sorry Charlie, but if you think their work was an unnecessary r= abbit 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. Da= ve Lenard flew his RV-6 behind Tracy's gearbox at Reno qualifying and t= otally torched the internal bearings. Regarding the transmission locked in = gear, I wouldn't stand near the plane that was using the gearbox regard= less of the time he had on it. It was a disaster waiting to happen. Everyon= e 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 t= hat you intend to return from in the same plane, you MUST account for torsi= onal vibration. The math isn't terribly tough nor are the parts a lot h= eavier, but the close meshing gears and stiff model never had a problem. Th= ey had to properly support the pinion gear, and after that the thing was bu= llet 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 beautif= ul torsional dampener into a rotary e-shaft that worked perfectly with a pl= anetary, 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 lot of damage, but if= you spend any time there even at idle you are going to break parts. I am t= ired of people thinking an auto conversion is too easy and then dead sticki= ng 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 b= roken 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:
=20 =20 =20
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; 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 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 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 and Everett Hatch did a LOT of work to be sure their "stiff" model reduction drive placed all the freq= uencies above the normal operating range. If you hit one of those frequencies with one of the 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 <flyrotary@lancaironline.net> 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 positive 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 are plotted, hence the smoothness of the rotary. When peak output is plotted it shows an always positive gentle wave.

Chrissi
CG Products=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0
=C2=A0


-----Original Message-----
From: William Jepson <flyrotary@lancaironline.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 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" <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:

"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 normally aspirated 2 liter and a 200 hp turbo version"

I did not mention a rotary engine specifically though.


Jay

On Mar 20, 2017, at 5:31 PM, Charlie England <flyrotary= @lancaironline.net> 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 closer to half that, so....


Charlie





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