X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mu-out-0910.google.com ([209.85.134.190] verified) by logan.com (CommuniGate Pro SMTP 5.2c4) with ESMTP id 2639130 for flyrotary@lancaironline.net; Thu, 10 Jan 2008 09:28:49 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.134.190; envelope-from=rotary.thjakits@gmail.com Received: by mu-out-0910.google.com with SMTP id w8so328147mue.4 for ; Thu, 10 Jan 2008 06:28:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; bh=nmVAntnOKb3c6UoB2fxpL/GTnYmQoiK53XP4ZCccxgM=; b=X/c2VDyYD5zajlFIcCdOG96XUACNMvbbFADDxlrftBsDQMotwWmX3IHew7QyXIXmkr3gRBMp1iYTDqOmQzHFO/ja4yXMdbmbu+r2EliWXowHzSC3v3+0lh29l9C8z5O5jw2tLJhoos51+vsxm73pPiNTeE8VrtSifknLuhz9wgw= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=QsZof8MrB0dRoYm23TDuIECF5Zp5YtMZIMjrxUneK9cUfXAcGc1qncPVlatzW8ImiN1ZWhIuQOuN9Cu3JkcPMNui0KMn4cNsK6kPfwhcLx1ZlunsRNmdqg1Bo885zkk00WZVpOn4SY0vYsNM3eEk7KFzMpcXJklsRtbVkl6ehoY= Received: by 10.78.123.4 with SMTP id v4mr2273391huc.18.1199975287669; Thu, 10 Jan 2008 06:28:07 -0800 (PST) Received: by 10.78.190.14 with HTTP; Thu, 10 Jan 2008 06:28:07 -0800 (PST) Message-ID: <63163d560801100628p686888fdi86995a80eb5a5068@mail.gmail.com> Date: Thu, 10 Jan 2008 09:28:07 -0500 From: "Thomas Jakits" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Magic Vapor Cycle Engines In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_10133_33293781.1199975287661" References: ------=_Part_10133_33293781.1199975287661 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline I have to rethink this.... Always thought, if youput the whole package onthe dyno it measures "what you get", like a chassis dyno, what you get is rearwheel-power minus slip.... What I want is a dyno to do my own little experiments, mainly motorcycle engine oriented (BMW airhead). I understand that with a generator I need the efficiency numbers for that specific gen. On the other hand I am not really in need of exact numbers. It doesn't matter if I have 70hp or 71 or 72,5 as long as the numbers are consistent. The idea is to see a change in specification/modification show up on the dyno... It has to be somehow lowcost!! Thanks for the posts! Thomas PS: Keep it coming if ideas appear! On Jan 7, 2008 9:36 AM, Ernest Christley wrote: > Charlie England wrote: > > Hi Thomas, > > > > If I understand your question, I think the assumptions might be > > reversed. My understanding is that any dyno, whether water brake, > > prop-loaded (air brake), etc. that uses the scale/lever technique is > > actually measuring raw engine torque. If you want to measure the > > losses in the gearbox and/or prop, you would measure thrust, convert > > to HP & compare to HP calculated from torque/rpm. > > If you are proposing measuring the output of a generator, you would be > > ignoring the losses in the inefficiency of the generator. That would > > be the equivalent of measuring only thrust in the previous example. > > > > If I'm in error, hopefully someone more knowledgeable will jump in. > > > > Charlie > > > > > > Thomas Jakits wrote: > >> Ooh yes! Pleease! > >> thjakits@gmail.com > >> > >> Thank you very much! > >> > >> Question to a possible "DIY/cheapo"-dyno: > >> I saw various plans/models where one bolts up the > >> engine/PSRU/club-prop and measures power via rpm x momentum (via > >> bathroomscale/lever). This gives me the overall hp - incl any losses > >> from the PSRU and inefficiencies fomr the prop. > >> What a about a pure engine-dyno? Drive a waterpump/generator (where > >> do I get a cheap 300kw generator??) ??? > >> > Maybe use a prop bolted directly to the output shaft. That gets around > the gearbox losses. A ducted fan would also be a little safer. Maybe > Perry can convert his old ducts and fans into a dyno business? > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > ------=_Part_10133_33293781.1199975287661 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline
I have to rethink this....
Always thought, if youput the whole package onthe dyno it measures "what you get", like a chassis dyno, what you get is rearwheel-power minus slip....
 
What I want is a dyno to do my own little experiments, mainly motorcycle engine oriented (BMW airhead).
I understand that with a generator I need the efficiency numbers for that specific gen.
On the other hand I am not really in need of exact numbers. It doesn't matter if I have 70hp or 71 or 72,5 as long as the numbers are consistent. The idea is to see a change in specification/modification show up on the dyno...
 
It has to be somehow lowcost!!
 
Thanks for the posts!
 
Thomas
 
PS: Keep it coming if ideas appear!

On Jan 7, 2008 9:36 AM, Ernest Christley <echristley@nc.rr.com> wrote:
Charlie England wrote:
> Hi Thomas,
>
> If I understand your question, I think the assumptions might be
> reversed. My understanding is that any dyno, whether water brake,
> prop-loaded (air brake), etc. that uses the scale/lever technique is
> actually measuring raw engine torque. If you want to measure the
> losses in the gearbox and/or prop, you would measure thrust, convert
> to HP & compare to HP calculated from torque/rpm.
> If you are proposing measuring the output of a generator, you would be
> ignoring the losses in the inefficiency of the generator. That would
> be the equivalent of measuring only thrust in the previous example.
>
> If I'm in error, hopefully someone more knowledgeable will jump in.
>
> Charlie
>
>
> Thomas Jakits wrote:
>> Ooh yes! Pleease!
>> thjakits@gmail.com <mailto:thjakits@gmail.com >
>>
>> Thank you very much!
>>
>> Question to a possible "DIY/cheapo"-dyno:
>> I saw various plans/models where one bolts up the
>> engine/PSRU/club-prop and measures power via rpm x momentum (via
>> bathroomscale/lever). This gives me the overall hp - incl any losses
>> from the PSRU and inefficiencies fomr the prop.
>> What a about a pure engine-dyno? Drive a waterpump/generator (where
>> do I get a cheap 300kw generator??) ???
>>
Maybe use a prop bolted directly to the output shaft.  That gets around
the gearbox losses.  A ducted fan would also be a little safer.  Maybe
Perry can convert his old ducts and fans into a dyno business?

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