X-CGP-ClamAV-Result: CLEAN X-VirusScanner: Niversoft's CGPClamav Helper v1.23.0 (ClamAV engine v0.103.0) X-Junk-Score: 0 [] X-KAS-Score: 0 [] From: "Stephen Izett stephen.izett@gmail.com" Received: from mail-pj1-f50.google.com ([209.85.216.50] verified) by logan.com (CommuniGate Pro SMTP 6.3.5) with ESMTPS id 377401 for flyrotary@lancaironline.net; Wed, 20 Oct 2021 18:50:51 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.216.50; envelope-from=stephen.izett@gmail.com Received: by mail-pj1-f50.google.com with SMTP id gn3so3557239pjb.0 for ; Wed, 20 Oct 2021 15:50:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:mime-version:subject:date:references:to:in-reply-to:message-id; bh=TJPUOsEkyBUDzu8dz9kQ9oDbCnxreEyX49QFAJK+3xs=; b=O/JWUorFWBvooxufaBF/Jk+ROA8gcLDksQfrxqHKuvT+j1QI7GSL3jSxR7Q8kIWwOY NVD7d4NbkQzxdTpy/zkMAOjJlcKByxBqO6g5XnULRZnuHuPADfzjw3z9o1Rgajfy8Ya/ vkM1iL0Feti/ZBzzL9swNVIlUVbD0dKXG2wPt3eBWbB2ljLSSIrMabvYYGWnCXPmXgaS khI9m11vumOZJRTvsHPBPKxNB5MmG5P9VAWS4MzRFcV9Pi8RFSSztNtF03bEJagR5D1O Fv2ymStl3FF4vwSZPo1Moob13PqI5M8aTkb4bJfy0mRzKHcZb6VG6Tbdl1klJgjc27GK DaZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:mime-version:subject:date:references:to :in-reply-to:message-id; bh=TJPUOsEkyBUDzu8dz9kQ9oDbCnxreEyX49QFAJK+3xs=; b=V74vt7OtQ7hYHse2+EZmT+XmUZl5MWznqBRYpl0ZOAFeBZDAeHZC61bu1X889F2REy fWps88OpQx9MNPGojymTHfnro3ttnwZMfpLiGRurJ419OjNpEZDJFsExU4ULjtRVLuuX mcV7m8x9vJ/xe+DK7IN4YJwBH3K8wyDhDeoeaEoNLMJoayCVp5mhJrrL3tUwjCSDGHCq D5Ltw0ROlXOQGVIfBLViUhwFCRLSkia29ivGflTqQdyIOS3q3IIe1yILMG8KygkLwJZe oPkCKOdkavRjL3aF9RsGrk6BwR6JAVThCfZHnbktbNEPORW1FTuAY5s2iRJzcxyVyfZY ED/Q== X-Gm-Message-State: AOAM532EJyj/tC35xywV61oANQxImMUyH1d/WZAs5U/mkhB/bno6ZaMm CnxTeIuf6Xriw34KX1trckbsGkFWv9o= X-Google-Smtp-Source: ABdhPJx4St1oH9zvEQY/nm/FyjwoUyXrSIxtKBPW9y5tpeqk2eLXtiQrsbDD0d4+TPTvd3KIkly+Gw== X-Received: by 2002:a17:90b:3ecc:: with SMTP id rm12mr2036878pjb.48.1634770234681; Wed, 20 Oct 2021 15:50:34 -0700 (PDT) Return-Path: Received: from smtpclient.apple (220-235-107-222.dyn.iinet.net.au. [220.235.107.222]) by smtp.gmail.com with ESMTPSA id 73sm3423387pfv.125.2021.10.20.15.50.32 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Oct 2021 15:50:34 -0700 (PDT) Content-Type: multipart/alternative; boundary="Apple-Mail=_F8BE083E-50AF-4D90-B4C7-E35C0F21B1EA" Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.120.0.1.13\)) Subject: Re: [FlyRotary] Props and gear boxes Date: Thu, 21 Oct 2021 06:50:29 +0800 References: To: Rotary motors in aircraft In-Reply-To: Message-Id: <61AE31C9-BD3F-4B2E-9675-0526A4CF6248@gmail.com> X-Mailer: Apple Mail (2.3654.120.0.1.13) --Apple-Mail=_F8BE083E-50AF-4D90-B4C7-E35C0F21B1EA Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Thanks for the real prop knowledge and feedback Charlie and Ed. Ground clearance is another area I=E2=80=99m left wondering about after = hearing what Charlie has played with. I think I=E2=80=99ll have just over 6.7 inches when the 72=E2=80=9D MT = goes on. I wasn=E2=80=99t game to go for 74=E2=80=9D. What clearance does an RV-xA have with a 72=E2=80=9D prop? Steve Izett > On 21 Oct 2021, at 2:23 am, eanderson@carolina.rr.com = wrote: >=20 > When I had Tracy's 2.17 PSRU, I swung a 67 dia x 72 pitch prop. Climb = and cruise were fine but takeoff (especially from a short runway on a = hot day left something to be desired). =20 >=20 > When I got Tracy's 2.85 PSRU, I had a 76 x80 wood prop build by = Performance propellers. I flew a few times with it as such and while = performance was much better rpm was only around 5800. Plus the prop was = only a couple inches from the ground on my RV-6A Nose gear aircraft - = was concerned about landing of grass strips with possible mole holes. = So I had the diameter reduced to 74 Inches. That was what the doctor = ordered. >=20 > There was a considerable difference in aircraft performance = particularly during take off. With the new combination, I had to tap = the left brake to keep runway alignment (if I cobbed full power from a = standing start) until airspeed reached approx 40 mph at which time the = rudder authority became adequate to hold the nose down the runway. = Starting acceleration was considerably better with the new combination, = it literally push me back in the seat. Climbout improved up to around = 1700 fpm previous had been around 1000 fpm. >=20 > I had thought I would probably have to give up a few knots on the top = end, but it turned out I actually increased airspeed by approx 4 mph. = So it was really a win win for me. I could get up to around 6200-6250 = WOT at cruise, so apparently at high airspeed the prop/gearbox unloaded = the engine to pick up a few more HP. >=20 > It appears that for takeoff there is nothing better than the volume = (mass) of air your prop is able to push behind it. So even though the = prop turned slower with the 2.85, the much larger prop and the engine = increase from a take off rpm of around 56-5700 rpm to 6000 and the = increased torque pushed a much larger volume (mass) of air. >=20 > I really like the change the 2.85 gear box made possible - oh, yeah, = now the prop also turned in the conventional direction.=F0=9F=98=84 >=20 > Ed >=20 > ------ Original Message ------ > From: "Charlie England ceengland7@gmail.com = " > > To: "Rotary motors in aircraft" > > Sent: 10/20/2021 9:01:32 AM > Subject: [FlyRotary] Re: Ag Ops >=20 >> Hi Steve, >>=20 >> I can't claim any expertise, but I do have some experience with = various prop diameters on RVs. Van started out recommending 68" dia = props on the 2 seat RVs. My 1st RV4 had a Warnke 72x72. With 160 HP, it = had 1200-1500fpm climb and would cruise at 170 kts @ ~9.3 gph rich of = peak, ~75% power for a Lyc 160. The cruise matched Van's numbers, and = climb was at least as good, if not better than Van's numbers. After my = partner in the RV damaged the Warnke, I replaced it with a 68" from = another mfgr and the plane never performed as well in either cruise or = climb. At one point, I tried a 76" dia IVO. Climb was incredible, but = the plane would hit a wall at about 145-150 kts (known problem with = IVO's blades; they don't have enough twist for high speed operation). = Another data point: Van's current catalog lists a Hartzel 74" dia c/s = prop for the 2 seat a/c and the f/p props are in the 72" dia range. >>=20 >> My calculations on optimum dia & ratio for the Renesis are similar to = yours. If you start with the Lyc-standard 2700 prop rpm, with the = realization that 74" is not too large a diameter (for tip speed issues) = at 2700, then the optimum ratio would be determined by your desired max = engine rpm. With a controllable prop, you can give up a little bit in = diameter & get back low speed thrust by going to flatter pitch & more = HP. But if fixed pitch, I try for the largest dia I can safely fit on = the plane. With a typical fast 2 seat homebuilt, gear leg length, not = tip speed, will almost always be the limiting factor even at 2700+ rpm. = The bigger the diameter, the better the low speed mass flow (thrust), = and there will be little to no penalty at any cruise speed under the = 180-190 kt range (well above 200 mph).=20 >>=20 >> The above assumes a properly designed prop, of course. One reason to = desire that 2.4-2.5:1 ratio is that it gets prop rpm where the prop = carver is used to working, and we're much more likely to get a usable = prop on 1st try if he's in familiar territory. If you tell him, say, 200 = HP @ 2700 prop rpm & cruise at 75% will be 170 kts, he'll likely be able = to get it right, 1st try. If, on the other hand, you're telling him the = same HP & speed, but you want, for instance, 76" dia & 2300 prop rpm, = he's going to be guessing on how to carve the prop. >>=20 >> Bottom line: I fit the largest dia I can safely swing, regardless of = f/p or c/s (because low speed thrust will always improve with diameter = increases), knowing that ground clearance will be a problem long before = tip speed becomes an issue. If you haven't already bought the 72", I'd = be asking them for a 76" if they'll sell you one and you can safely = swing it on your plane. And be sure to tell them the actual rpm range = where it will operate. Their 'stock' 72" for a Lyc will be sub-optimal = turning in the ~2000 rpm range with a 2.85 drive, unless you intend to = really flog the engine hard all the time & pour a lot of fuel through = it. >>=20 >> FWIW, >>=20 >> Charlie >>=20 >> On Tue, Oct 19, 2021 at 7:38 PM Stephen Izett stephen.izett@gmail.com = > wrote: >> Hi Andrew >>=20 >> Continuing to fine tune the Renesis cooling system and aircraft. >> Completing a new exhaust system after a leaking gasket warped a = flange. >> Last flight temps max=E2=80=99d at 91C (196F) on takeoff with 20C = (68F)OAT and we got her up to 189knots but only 2600 feet due to cloud. >> Learning that increasing the IAS by ~10knots in climb has a = significant effect on cooling. >>=20 >> Also in the process of changing the current 66.5=E2=80=9D Airmasterto = for a 72=E2=80=9D MT prop. >> I only read after going with our gearbox/prop combination that Tracy = recommended only using the 2.85:1 with props of >=3D74=E2=80=9D >> For those with expertise in this area, is it true that we should = choose: >> 1. Largest prop dimeter with acceptable clearance >> 2. Target cruise tip speed of ~0.8-0.85 speed of sound for best = efficiency >> If this is correct then with a 72=E2=80=9D prop and a chosen engine = redline of 7500 RPM (4 port Renesis) a better gearbox ratio would be = ~2.5:1 >> The 2.85:1 would be better suited to a 74-76=E2=80=9D prop at that = redline. >>=20 >> Hope you have a great harvest and get back in the air soon Andrew. >>=20 >> Steve >>=20 >>=20 >>> On 20 Oct 2021, at 7:52 am, Andrew Martin andrew@martinag.com.au = > wrote: >>>=20 >>> Hi Steve, hows the Glasair going? I been away from flying for = awhile, hopefully back into it in new year. Did start mine recently = after it been sitting idle since feb 2020, So happy I persevered with = the mazda, it started & ran so sweet I contemplated doing a couple of = circuits but for the legalities. No MR and I need AFR first. >>>=20 >>> Neil, not sure I agree with your rotor setup proposal, ( not that = mine is better) can get some weird aerodynamics with intermeshing = rotors. >>> Whole thing of nurse cart & drone need to be a package, rotors will = never be stopped during refill so drone needs to land on roof of truck = or trailer for refill from underneath to keep blades clear of dumbasses = like me. >>> Truth be told, I dont think we can get anywhere near the efficiency = of a ground rig or Ag plane, we easily average 80 ha/hr each machine + = nurse cart, going to need a swarm of drones to get near this. But could = be a fun project. >>> Andrew >>>=20 >>> On Tue, 19 Oct. 2021, 9:07 am Stephen Izett stephen.izett@gmail.com = , > wrote: >>> Good to hear your voice Andrew. >>> My son-in-law in Kojonup would be very interested in what you guys = are talking about. >>>=20 >>> Cheers >>>=20 >>> Steve Izett >>>=20 >>>> =20 >>>>=20 >>>>=20 >>>=20 >>> --=20 >>> Regards Andrew Martin Martin Ag --Apple-Mail=_F8BE083E-50AF-4D90-B4C7-E35C0F21B1EA Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 Thanks for the real prop knowledge and feedback Charlie and = Ed.

Ground clearance = is another area I=E2=80=99m left wondering about after hearing what = Charlie has played with.
I think I=E2=80=99ll have = just over 6.7 inches when the 72=E2=80=9D MT goes on. I wasn=E2=80=99t = game to go for 74=E2=80=9D.
What clearance does an = RV-xA have with a 72=E2=80=9D prop?

Steve Izett






On 21 Oct 2021, at 2:23 am, eanderson@carolina.rr.com <flyrotary@lancaironline.net> wrote:

When I had Tracy's 2.17 PSRU, I swung = a 67 dia x 72 pitch prop.  Climb and cruise were fine but takeoff = (especially from a short runway on a hot day left something to be = desired).  

When I got Tracy's 2.85 PSRU, I had a 76 x80 wood prop = build by Performance propellers.  I flew a few times with it as = such and while performance was much better rpm was only around = 5800.  Plus the prop was only a couple inches from the ground on my = RV-6A Nose gear aircraft - was concerned about landing of grass strips = with possible mole holes.  So I had the diameter reduced to 74 = Inches.  That was what the doctor ordered.

There was a considerable difference = in aircraft performance particularly during take off.  With the new = combination, I had to tap the left brake to keep runway alignment (if I = cobbed full power from a standing start) until airspeed reached approx = 40 mph at which time the rudder authority became adequate to hold the = nose down the runway.  Starting acceleration was considerably = better with the new combination, it literally push me back in the = seat.  Climbout improved up to around 1700 fpm previous had been = around 1000 fpm.

I had thought I would probably have to give up a few = knots on the top end, but it turned out I actually increased airspeed by = approx 4 mph.  So it was really a win win for me.  I could get = up to around 6200-6250 WOT at cruise, so apparently at high airspeed the = prop/gearbox unloaded the engine to pick up a few more HP.

It appears that for takeoff there is = nothing better than the volume (mass) of air your prop is able to push = behind it.  So even though the prop turned slower with the 2.85, = the much larger prop and the engine increase from a take off rpm of = around 56-5700 rpm to 6000 and the increased torque pushed a much larger = volume (mass) of air.

I really like the change the 2.85 gear box made = possible - oh, yeah, now the prop also turned in the conventional = direction.=F0=9F=98=84

Ed

------ Original Message ------
From: "Charlie England ceengland7@gmail.com" = <flyrotary@lancaironline.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: 10/20/2021 9:01:32 AM
Subject: [FlyRotary] Re: Ag Ops

Hi Steve,

I can't claim any expertise, but I do have = some experience with various prop diameters on RVs. Van started out = recommending 68" dia props on the 2 seat RVs. My 1st RV4 had a Warnke = 72x72. With 160 HP, it had 1200-1500fpm climb and would cruise at 170 = kts @ ~9.3 gph rich of peak, ~75% power for a Lyc 160. The cruise = matched Van's numbers, and climb was at least as good, if not better = than Van's numbers. After my partner in the RV damaged the Warnke, I = replaced it with a 68" from another mfgr and the plane never performed = as well in either cruise or climb. At one point, I tried a 76" dia IVO. = Climb was incredible, but the plane would hit a wall = at about 145-150 kts (known problem with IVO's blades; they don't = have enough twist for high speed operation). Another data point: = Van's current catalog lists a Hartzel 74" dia c/s prop for the 2 seat = a/c and the f/p props are in the 72" dia range.

My calculations on optimum dia & ratio for the Renesis are = similar to yours. If you start with the Lyc-standard 2700 prop rpm, with = the realization that 74" is not too large a diameter (for tip speed = issues) at 2700, then the optimum ratio would be determined by your = desired max engine rpm. With a controllable prop, you can give up a = little bit in diameter & get back low speed thrust by going to = flatter pitch & more HP. But if fixed pitch, I try for the largest = dia I can safely fit on the plane. With a typical fast 2 seat homebuilt, = gear leg length, not tip speed, will almost always be the limiting = factor even at 2700+ rpm. The bigger the diameter, the better the low = speed mass flow (thrust), and there will be little to no penalty at any = cruise speed under the 180-190 kt range (well above 200 = mph). 

The above assumes a properly designed prop, = of course. One reason to desire that 2.4-2.5:1 ratio is that it gets = prop rpm where the prop carver is used to working, and we're much more = likely to get a usable prop on 1st try if he's in familiar territory. If = you tell him, say, 200 HP @ 2700 prop rpm & cruise at 75% will = be 170 kts, he'll likely be able to get it right, 1st try. If, on the = other hand, you're telling him the same HP & speed, but you want, = for instance, 76" dia & 2300 prop rpm, he's going to be guessing on = how to carve the prop.

Bottom line: I fit = the largest dia I can safely swing, regardless of f/p or c/s (because = low speed thrust will always improve with diameter increases), knowing = that ground clearance will be a problem long before tip speed becomes an = issue. If you haven't already bought the 72", I'd be asking them for a = 76" if they'll sell you one and you can safely swing it on your plane. = And be sure to tell them the actual rpm range where it will operate. = Their 'stock' 72" for a Lyc will be sub-optimal turning in the ~2000 rpm = range with a 2.85 drive, unless you intend to really flog the engine = hard all the time & pour a lot of fuel through it.

FWIW,

Charlie

On Tue, Oct = 19, 2021 at 7:38 PM Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
Hi Andrew

Continuing to fine tune = the Renesis cooling system and aircraft.
Completing = a new exhaust system after a leaking gasket warped a flange.
Last flight temps max=E2=80=99d at 91C (196F) on takeoff with = 20C (68F)OAT and we got her up to 189knots but only 2600 feet due to = cloud.
Learning that increasing the IAS by ~10knots = in climb has a significant effect on cooling.

Also in the process of changing the = current 66.5=E2=80=9D Airmasterto for a 72=E2=80=9D MT prop.
I only read after going with our gearbox/prop combination = that Tracy recommended only using the 2.85:1 with props of = >=3D74=E2=80=9D
For those with expertise in this = area, is it true that we should choose:
1. Largest = prop dimeter with acceptable clearance
2. Target = cruise tip speed of ~0.8-0.85 speed of sound for best = efficiency
If this is correct then with a 72=E2=80=9D= prop and a chosen engine redline of 7500 RPM (4 port Renesis) a better = gearbox ratio would be ~2.5:1
The 2.85:1 would be = better suited to a 74-76=E2=80=9D prop at that redline.

Hope you have a great = harvest and get back in the air soon Andrew.

Steve


On 20 Oct 2021, at 7:52 am, Andrew = Martin andrew@martinag.com.au <flyrotary@lancaironline.net> wrote:

Hi Steve, hows the Glasair going? I been away from = flying for awhile, hopefully back into it in new year. Did start mine = recently after it been sitting idle since feb 2020, So happy I = persevered with the mazda, it started & ran so sweet I contemplated = doing a couple of circuits but for the legalities. No MR and I need AFR = first.

Neil, not sure I agree with your rotor setup proposal, ( not = that mine is better) can get some weird aerodynamics with intermeshing = rotors.
Whole thing of nurse = cart & drone need to be a package, rotors will never be stopped = during refill so drone needs to land on roof of truck or trailer for = refill from underneath to keep blades clear of dumbasses like = me.
Truth be told, I dont think we can = get anywhere near the efficiency of a ground rig or Ag plane, we easily = average 80 ha/hr each machine + nurse cart, going to need a swarm of = drones to get near this. But could be a fun project.
Andrew

On Tue, 19 Oct. 2021, 9:07 am Stephen = Izett stephen.izett@gmail.com, <flyrotary@lancaironline.net> wrote:
Good to hear your voice = Andrew.
My son-in-law in Kojonup would be very interested = in what you guys are talking about.

Cheers

Steve Izett

 



-- 
Regards Andrew Martin Martin = Ag

= --Apple-Mail=_F8BE083E-50AF-4D90-B4C7-E35C0F21B1EA--