X-Virus-Scanned: clean according to Sophos on Logan.com From: "James R. Osborn" Received: from mail-pa0-f42.google.com ([209.85.220.42] verified) by logan.com (CommuniGate Pro SMTP 6.1.7) with ESMTPS id 8175393 for flyrotary@lancaironline.net; Thu, 19 Nov 2015 12:37:13 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.220.42; envelope-from=rxcited@gmail.com Received: by pabfh17 with SMTP id fh17so90231911pab.0 for ; Thu, 19 Nov 2015 09:36:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=content-type:mime-version:subject:from:in-reply-to:date :content-transfer-encoding:message-id:references:to; bh=gdS8lGGsjMXecGTfmWfRTGc83UmxJZOgExl+IuOUx0E=; b=J3Jtiryvlh+D34brFscTp2wC3VqmJMhMkWn81LE4wfM2XBiYWNxHI5mBkmbt5hj2Yp xdiARIe4c1/15TBdUzHygGiO74m15+6UCj4Aob042vmua9eiwWwkDubDhY+RDJ0gms8r 2JJUOwxAmbZkcZfeap5/Y6Z/yzUN1YJaLuTKo/WgkA52obzro4A1n7EcNBdyYgrdY00r ua5c+t3/eqkZIkFi7Jc2P0eJMO8ZBV+fF2xgZB+ahTY6Z4PzZmWocTbkmncOxqeZMy86 EDhAzvhH/X9SORGYO8cSb5DN9riFYBzvpiGAYNA+VJfW83LMInSmKO7xZqR6gGv1bpSb aIBg== X-Received: by 10.66.158.129 with SMTP id wu1mr12414797pab.146.1447954615436; Thu, 19 Nov 2015 09:36:55 -0800 (PST) Return-Path: Received: from ?IPv6:2620:83:8001:24::1:1c35? ([2620:83:8001:24::1:1c35]) by smtp.gmail.com with ESMTPSA id vk10sm11888323pbc.66.2015.11.19.09.36.54 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 19 Nov 2015 09:36:54 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) Subject: Re: [FlyRotary] 20B with RD-1C Prop Options In-Reply-To: Date: Thu, 19 Nov 2015 09:36:56 -0800 Content-Transfer-Encoding: quoted-printable Message-Id: References: To: Rotary motors in aircraft X-Mailer: Apple Mail (2.2104) Hi Jeff, Yes no time pressure at all. This will be a test stand development. We don=E2=80=99t know the full providence of this motor. It appears = that it has been rebuilt and there is rumor that Bruce Turrentine was = involved with that. He has a reputation, but I don=E2=80=99t know if it = true he rebuilt it or wishful thinking. And I don=E2=80=99t know what = kind of porting was done - it looks more like just cleanup than porting = from the outside inspection, but I wouldn=E2=80=99t know for sure until = and if I take it apart. I am not too afraid of rebuilding it as I have plenty of 13B experience. = But if the numbers seemed acceptable, I was thinking I would try avoid = it. Peak HP considerations aside (as Bobby mentioned), I am inclined to = go PP if I tear it apart - I always wanted one! This would eliminate = unknown factors about porting altogether too. =E2=80=94 James > On Nov 19, 2015, at 5:03 AM, Jeff Whaley = wrote: >=20 > My gut feeling is if you are confident in the engine's history then = run the engine for several hours and retest the compression numbers. > Don't know where your engine came from, how long it has been sitting, = or what preservation treatment it received. In general terms it is = always best to overhaul an automotive engine prior to installation in an = aircraft. My guess is if you are building an RV10, you are still a long = way from actually flying? - If that is true you will have plenty of time = to perform an overhaul - it takes about 1-2 weeks real time. > Jeff >=20 > -----Original Message----- > From: James R. Osborn [mailto:flyrotary@lancaironline.net] > Sent: Wednesday, November 18, 2015 9:05 PM > Subject: Re: 20B with RD-1C Prop Options >=20 > So I finally got a dynamic pressure test done on this 20B. Here is = what I got: >=20 > Front: 105-125-105 > Center: 105-101-87 > Rear: 130-125-120 >=20 > This is in PSI and was done with all spark plugs out except the rotor = being tested. That one got one spark plug and the compression fitting = with pressure transducer attached in the other. I used the RD-1C = installed, but not engaged - I bolted up the flex plate without the = adapter and bolted up the RD-1C with a starter to be able to crank it = over. So the redrive was not slowing things down when I cranked it = over. Then I recorded the pressure wave on a laptop and looked at three = bumps in a row. I did this a few times for each rotor with a pause in = between and took the highest readings of any three successive peaks to = estimate the health of the three faces on each rotor. >=20 > My understanding is that higher numbers are better and the same = numbers across all faces in the motor is better. I am unclear what an = unacceptable low number might be. The actual values you get are = dependent on a number of factors including how fast you are cranking = (how well charged your battery is, how beefy the cables are, what kind = of porting, other losses like the PSRU if it were engaged, etc.) and if = the motor is broken in or not. I don=E2=80=99t know if this motor was = broken in, or if any seals were replaced. It looks clean inside and = there is evidence of porting, but I don=E2=80=99t know exactly what = (this is a side port configuration motor). >=20 > When I lost a side seal on my 13B REW in my RX-7, I got something like = 118-120-50 on the rotor that had the problem. So that was clearly not = good. When I rebuilt that motor that time, I had the plates ground as = they were beyond the wear limit and I used all new side and corner seals = and springs. After that rebuild, I got uniformly 120 to 130 on all = faces which I think is very good. >=20 > So, what do you guys think of my 20B numbers? Is that low face on the = Center rotor bad enough to warrant tearing the motor completely apart? = If I decide to do that, I might very well go PP. Though Bobby at least = thinks that is a bad idea due to noise and tuning difficulties with the = PP. Or I could just live with it with these numbers, go side port, and = break it in and start checking this periodically to see if there is any = improvement or further deterioration. >=20 > Thoughts or opinions? >=20 > =E2=80=94 James >=20 >> On Oct 29, 2015, at 1:22 PM, James R. Osborn = wrote: >>=20 >> Hi guys, >>=20 >> So I am going to be building an RV-10. I sourced Bobby=E2=80=99s = spare 20B / RD-1C combo and my plan is to work on the motor first, kind = of bass-ackward but that is what I am doing. My plan is to build a = motor/mount test stand and work everything out on the ground before I = ever put it in an airframe. I plan to set it up NA using the existing = side port configuration. I don=E2=80=99t know if it is ported - I am = going to attempt to determine this by inspection without cracking it = open and doing a dynamic compression test to evaluate the health of the = motor. If it is necessary to entirely rebuild the motor, I would = probably go PP. So I am thinking the target HP as it is would be in the = 275 HP range and probably 325 HP if it ends up being a PP. How do these = numbers sound to you all? >>=20 >> I will be looking for a way to dyno it, hopefully borrow one to get = some data. But I was also thinking about just getting an appropriate = fixed pitch prop and working through the bugs based on static run ups. = I like the idea of a three blade prop. I like the idea of optimizing = for cruise at 75%, say 5800 rpm which would put full throttle at 7733 = rpm on the 20B. At 5800 rpm, the prop would be spinning 2035 rpm and at = full throttle 2713 rpm (using the 2.85 ratio RD-1C PSRU). Do all these = numbers sound about right? >>=20 >> If so, then how do I choose a prop that will result in 2713 rpm = static run up at full throttle, but be tuned for efficiency at 2035 rpm = cruise? I am assuming at these reasonable RPMs that it will be a larger = swing and the three blade makes sense - what do you think? Is there a = convenient way to find props out there that will work at the target full = throttle HP of 275 or 325? Also if you guys have any good resources to = learn about how to figure these things out (books, web pages, online = calculators, etc.) that would be great! >>=20 >> Another option might be to go with something like the IVOPROP Magnum, = either ground adjustable or electric inflight adjustable. What do you = guys think of these? Would the adjustability really help me adapt to = however my power plant turns out? Would the extra complexity be worth = it? For the ground adjustable one, I am thinking the process would be: = 1. select the =E2=80=9Ccorrect=E2=80=9D swing (how?) and go for three = blades, 2) use ground adjustability and work up to THE pitch while I = tune the motor until I achieve full throttle static run up around 7700 = RPM. Will this result in a reasonably efficient setting for 75% cruise? = Am I thinking about this clearly? All opinions are welcome. >>=20 >> There=E2=80=99s a lot for you to chew on! >>=20 >> =E2=80=94 James >>=20 >=20 > This message, and the documents attached hereto, is intended only for = the addressee and may contain privileged or confidential information. = Any unauthorized disclosure is strictly prohibited. If you have received = this message in error, please notify us immediately so that we may = correct our internal records. Please then delete the original message. = Thank you. >=20 > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html