X-Virus-Scanned: clean according to Sophos on Logan.com From: "Charlie England" Received: from mail-pf0-f173.google.com ([209.85.192.173] verified) by logan.com (CommuniGate Pro SMTP 6.2c1) with ESMTPS id 9598122 for flyrotary@lancaironline.net; Wed, 22 Mar 2017 15:22:07 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.192.173; envelope-from=ceengland7@gmail.com Received: by mail-pf0-f173.google.com with SMTP id 20so47899561pfk.2 for ; Wed, 22 Mar 2017 12:22:07 -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=fNx7u4W2b4FOG5zUJdBrdLZLwc8V8Oz7uPOCrAz+BCY=; b=NA4EHCOMCbEy8XoDKzlvBD79+KuxOt3Yfu0y8VZyQfN1OuxM/ahNgMJQaBseQ2UnPP gJRmcj1jYWsKClqTlycs0GGLZfOAbidBz+TfHGxL73dm6Hac0ZWSvv27lZZA3PqEpP1S ACTjWk5rXC0w/zljSFxgGXsn+OVvA4vzLZBwWAsoIggnOCpVMRoD2lMvi4ODQoososR4 e9aBcpJvpjA32mmmtZbylMld5qa8RXQsQf8VOw0PFyrBfnJm0NHHXEQxZzF4aIsifK5G D+Wc/jKK0RQ3lcrc+zEAPssmDkcc82BhhKgcricmrgln/QFqVOaSv/mUVQBzGCwW6nii o1VQ== 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=fNx7u4W2b4FOG5zUJdBrdLZLwc8V8Oz7uPOCrAz+BCY=; b=fsTRwPZdvEZD3LIPYcYBM3X4RumU+6IBMqA41WnfP1SF5OZN+k1xb2rA7bHL9O5HQB tSSxemKl8+d7DcaZceX0MdS2I4D98H7Pb8tH6SsHp4wWZpTINz2c3bavZpewySupCSKf lXBm4OlymxEyci7fyyejq+0uJC24/7j67Kxif8H+cx7VUcgFCSso4++YpM0iQL9rzTl+ UBhRmR/aHBbaLLq/uSPR0QoYmNxnMexpvDGebuOvYVeQO7ZW84VYuiwhHj+nF417t11v xZu+vmqkRsxRTJ7OBe66476l90wlXlF0BnZXgdlICet8qVAOmowiLMVQRm/h52ApLI5x /raw== X-Gm-Message-State: AFeK/H0A3/d5KnCh/xbRhG9PXJnD1uw1Wr8InSaepCGbFs7YWb4515f4gTTPnm36+cHTdKO9h4c24YC2LscH8w== X-Received: by 10.99.173.6 with SMTP id g6mr44271371pgf.75.1490210509582; Wed, 22 Mar 2017 12:21:49 -0700 (PDT) MIME-Version: 1.0 Received: by 10.100.128.83 with HTTP; Wed, 22 Mar 2017 12:21:48 -0700 (PDT) In-Reply-To: References: Date: Wed, 22 Mar 2017 14:21:48 -0500 Message-ID: Subject: Re: [FlyRotary] Re: redrive options To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=94eb2c1bef26107ca3054b56acf4 --94eb2c1bef26107ca3054b56acf4 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable I really hope you don't go silent; I'm grateful for your input. However, some of the things you've said in earlier posts seemed to say, at least when I read them, that nothing but the close tolerance stiff system would work, and I fear that others will read them the same way. I'm glad to know that I've been wrong about how you feel about other designs and I'm truly sorry if I offended; that wasn't my intent. I certainly wasn't advocating the use of car transmissions in a/c. I only mentioned it as an extreme example of what one might get away with, if resonance is avoided (and the system isn't simply overpowered). That particular builder was just fortunate enough to avoid danger points in flight, by luck; not design. Just out of curiosity, how many of the Powersport drives are flying on rotaries now? Any idea on number of hours on the highest time unit? Charlie On Wed, Mar 22, 2017 at 1:41 PM, William Jepson wrote: > OK, I first want to mention my reason for involvement in ANY gearbox > design. I want to use if for myself. I'm building an RV-10 which will > require a safe gearbox with 300 HP (so there is some legitimate headroom = on > the 260 HP rating.) My siting of examples is relevant only because I want > people to be aware that there are forces here that aren't obvious. Even > good engineering requires scrutiny. Tracy's gearbox was a good effort, an= d > designed to a lower price. Used within normal power ranges it is fine. > Powersport's earlier efforts had excellent design, but before they did > pinion end support even their efforts had some failures. That is my POINT= , > not an obfuscation. Every time the car transmission example is brought up > it totally muddies the waters. We don't know what power ranges or RPMs > the owner/pilot used to keep it running. > I have no concern whatsoever for who builds a gearbox. I would love to > be able to buy one from someone. I have no concern which model, soft or > stiff they use. I don't and didn't say a soft system wouldn't work. I onl= y > am saying that it requires just as much consideration of the forces > involved as a stiff system. I also don't like to have the need to cross o= ne > of the resonance ranges every time I start or stop my engine. Look up the > BD-5 they did a soft system that worked well in operation, but found that > they could sometimes "hang" the system while turning it over on the > electric starter! I HAVE ONLY 1 MOTIVATION HERE. I DON'T WANT PEOPLE > DISCOUNTING TORSIONAL VIBRATION FORCES AND HAVING FAILURES THAT MIGHT CAU= SE > THEM TO CRASH. I have no profit motive as I may never find it practical t= o > produce anything as a sideline to my "regular" job. If I did it would onl= y > be to defray the cost of building my own. I am hoping that I can be a > repository for some of the Powersport knowledge for Steve so it won't get > wasted or thrown away. Every time I discuss this stuff someone wants to > discount it. Or say some guy just ran a car transmission locked in gear > what's the big deal? At this point I am considering going silent and neve= r > commenting again. I would have far fewer problems to deal with. > Bill Jepson > > On Wed, Mar 22, 2017 at 6:20 AM, Charlie England < > flyrotary@lancaironline.net> wrote: > >> 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 s= o >> long. I'm glad it's being revived, too. And I agree that designing/build= ing >> 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 avoi= ded >> 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 ho= urs >> 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 can= not >> 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 be= en >> demonstrated to fail if operated incorrectly, but because they're operat= ed >> 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 m= ass >> to the flywheel, or...etc etc. >> >> Charlie >> >> >> >> On Tue, Mar 21, 2017 at 7:13 PM, William Jepson < >> flyrotary@lancaironline.net> wrote: >> >>> Charlie, >>> No they build a complete gearbox using planetary gears first. (spur onl= y >>> so no end thrust) They found as you ran the engine through various spee= d >>> ranges it was possible to incur damage due to second order vibrations t= hat >>> could be just as damaging. Sorry Charlie, but if you think their work w= as >>> 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 u= sing >>> the gearbox regardless of the time he had on it. It was a disaster wait= ing >>> 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, = you >>> MUST account for torsional vibration. The math isn't terribly tough nor= are >>> the parts a lot heavier, but the close meshing gears and stiff model ne= ver >>> 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 that are even close to the same weight. The >>> guys built a beautiful torsional dampener into a rotary e-shaft that wo= rked >>> perfectly with a planetary, it just required too much expensive machini= ng. >>> Your comment about in resonance problems being regardless of power leve= l 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 t= o >>> break parts. I am tired of people thinking an auto conversion is too ea= sy >>> and then dead sticking their plane in a field somewhere. (As a best cas= e) >>> 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 d= id >>>> tell me that *in resonance*, power level doesn't really matter much; s= tuff >>>> 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 & r= pm >>>> where their failure occurred. Doesn't it make you wonder if the result= s >>>> 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 weig= ht. >>>> >>>> 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 b= een >>>> 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 p= ulses >>>> 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 cau= sing >>>> 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 t= he >>>> normal operating range. If you hit one of those frequencies with one o= f the >>>> rubber couplings or the bushing-around-bolt dampers it will fail perio= d. >>>> 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 eno= ugh >>>> to pass through that RPM without damage. Usually. But if not planned f= or >>>> 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 revolu= tion >>>>> of a traditional 4 cylinder aircraft engine which shows as a spiky po= sitive >>>>> 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 for= ms are >>>>> plotted, hence the smoothness of the rotary. When peak output is plot= ted 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 >>>>> 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 >>>>> >>>>> >>>> >>>> >>> >> > --94eb2c1bef26107ca3054b56acf4 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
I really hope you don't go silent; I'm grateful fo= r your input. However, some of the things you've said in earlier posts = seemed to say, at least when I read them, that nothing but the close tolera= nce stiff system would work, and I fear that others will read them the same= way. I'm glad to know that I've been wrong about how you feel abou= t other designs and I'm truly sorry if I offended; that wasn't my i= ntent.

I certainly wasn't advocating the use of car = transmissions in a/c. I only mentioned it as an extreme example of what one= might get away with, if resonance is avoided (and the system isn't sim= ply overpowered). That particular builder was just fortunate enough to avoi= d danger points in flight, by luck; not design.=C2=A0

<= div>Just out of curiosity, how many of the Powersport drives are flying on = rotaries now? Any idea on number of hours on the highest time unit?

Charlie




On Wed, Mar 22, 2017 at 1:41 P= M, William Jepson <flyrotary@lancaironline.net> wr= ote:
= OK, I first want to mention my reason for involvement in ANY gearbox design= . I want to use if for myself. I'm building an RV-10 which will require= a safe gearbox with 300 HP (so there is some legitimate headroom on the 26= 0 HP rating.) My siting of examples is relevant only because I want people = to be aware that there are forces here that aren't obvious. Even good e= ngineering requires scrutiny. Tracy's gearbox was a good effort, and de= signed to a lower price. Used within normal power ranges it is fine. Powersport's earlier eff= orts had excellent design, but before they did pinion end support even thei= r efforts had some failures. That is my POINT, not an obfuscation. Every ti= me the car transmission example is brought up it totally muddies the waters= . We don't know what power ranges or RPMs the owner/pilot used to keep it running.=C2=A0
= =C2=A0 I have no concern whatsoever for who builds a gearbox. I would love = to be able to buy one from someone. I have no concern which model, soft or = stiff they use. I don't and didn't say a soft system wouldn't w= ork. I only am saying that it requires just as much consideration of the fo= rces involved as a stiff system. I also don't like to have the need to = cross one of the resonance ranges every time I start or stop my engine. Loo= k up the BD-5 they did= a soft system that worked well in operation, but found that they could som= etimes "hang" the system while turning it over on the electric st= arter!=C2=A0 I HAVE ONLY 1 MOTIVATION HERE. I DON'T WANT PEOPLE DISCOUN= TING TORSIONAL VIBRATION FORCES AND HAVING FAILURES THAT MIGHT CAUSE THEM T= O CRASH. I have no profit motive as I may never find it practical to produc= e anything as a sideline to my "regular" job. If I did it would o= nly be to defray the cost of building my own. I am hoping that I can be a r= epository for some of the Pow= ersport knowledge for Steve so it won't get wasted or thrown awa= y. Every time I discuss this stuff someone wants to discount it. Or say som= e guy just ran a car transmission locked in gear what's the big deal? A= t this point I am considering going silent and never commenting again. I wo= uld have far fewer problems to deal with.=C2=A0
Bill Jepson

On Wed, Mar 22, 2017 at 6:20 AM, = Charlie England <flyrotary@lancaironline.net> wrot= e:
I&= #39;m sorry if I gave the impression that their work wasn't valuable. I= t 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 th= at 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 enginee= rs tell us, and also in the face of empirical evidence. I don't doubt t= hat they had all the problems you describe. But designing around *every con= ceivable* configuration =C2=A0& condition is pretty difficult, and ofte= n, not required. The trick is to know where the issues lie, and be sure tha= t they're avoided in operation.=C2=A0

You ment= ion Dave Leonard torching RWS bearings, but fail to mention the torched bea= rings in the Powersport time to climb attempt at Sun N Fun a couple of deca= des ago. I don't consider either incident relevant to the discussion, s= ince both were outside of normal operating parameters and neither involved = torsional resonance issues. Throwing out such examples just muddy the water= s 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 prob= lems until one day it got operated in a condition far outside normal condit= ions.)

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 ta= ch where the engine cannot be operated continuously, and they're there = because of resonance issues. The Sensenich fixed pitch aluminum prop for 16= 0 HP Lycs on RV-x's (thousands in operation) is placarded against opera= tion 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 th= ey're operated in compliance with posted restrictions they're safe.=

The Powersport research was a for-profit operatio= n, so for good reason (for them), the full body of research has, to my know= ledge, never been published. If it was published, we might see any number o= f factors that show their earlier designs could be operated safely by simpl= y avoiding continuous operation at resonance points, or avoiding the use of= heavy metal props, or changing the compliance of the soft coupler, or addi= ng mass to the flywheel, or...etc etc.

Charlie



On Tue, Mar 21, 2017 a= t 7:13 PM, William Jepson <flyrotary@lancaironline.net> wrote:
Charlie,
No they build a complete gearbox using planetary gear= s first. (spur only so no end thrust) They found as you ran the engine thro= ugh various speed ranges it was possible to incur damage due to second orde= r vibrations that could be just as damaging. Sorry Charlie, but if you thin= k their work was an unnecessary rabbit hole I won't be flying in your p= lane. 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. Rega= rding 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 di= saster waiting to happen. Everyone thinks this is easy. You can get away wi= th it for a while but if you want to use your engine at a significant HP le= vel, for a cross country flight that you intend to return from in the same = plane, you MUST account for torsional vibration. The math isn't terribl= y tough nor are the parts a lot heavier, but the close meshing gears and st= iff 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 a= ny 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-shaf= t that worked perfectly with a planetary, it just required too much expensi= ve machining. Your comment about in resonance problems being regardless of = power level is true. Fortunately you can usually transition the specific rp= m 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 problem. Automotive engines are= built pretty well today, but a broken gearbox, or drive belt, or torque co= nverter, 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 <fl= yrotary@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







--94eb2c1bef26107ca3054b56acf4--