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: " eanderson@carolina.rr.com" Received: from [47.43.26.135] (HELO p-impout004.msg.pkvw.co.charter.net) by logan.com (CommuniGate Pro SMTP 6.3.5) with ESMTPS id 376857 for flyrotary@lancaironline.net; Wed, 20 Oct 2021 14:23:17 -0400 Received-SPF: pass receiver=logan.com; client-ip=47.43.26.135; envelope-from=eanderson@carolina.rr.com Received: from [127.0.0.1] ([66.26.212.217]) by cmsmtp with ESMTP id dGEtmle44UVrzdGEumOTO7; Wed, 20 Oct 2021 18:23:00 +0000 X-Authority-Analysis: v=2.4 cv=Ztool/3G c=1 sm=1 tr=0 ts=61705e84 a=WcvdwKkRgKsaRaJ9Bx4DbQ==:117 a=WcvdwKkRgKsaRaJ9Bx4DbQ==:17 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=eRLigfuSAAAA:8 a=et1uWwYMo8GWBUmg_u4A:9 a=QEXdDO2ut3YA:10 a=4PR2P7QzAAAA:8 a=-k2w48aTycaZ82prP9AA:9 a=NA8hOL-pmxns4kRp:21 a=frz4AuCg-hUA:10 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=BfhXYjFvZD4iae-mNffo:22 a=4dqwQCo7Po2mVW515mGf:22 To: "Rotary motors in aircraft" Subject: Props and gear boxes Date: Wed, 20 Oct 2021 18:23:00 +0000 Message-Id: In-Reply-To: References: Reply-To: eanderson@carolina.rr.com User-Agent: eM_Client/8.2.1509.0 Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="------=_MBD721955E-B167-414D-9B27-7112B546B004" X-CMAE-Envelope: MS4xfASSGnObY7UlrkHEWEUA9x4Ck/9tjT20kJfGlZfx8W3q14ejm9pKuvt0heuLZzuFCbwjx+0z4D0uQhUbFDYwg9hklLD1JXREDbNaD6/oOL8XmsRTgxOO V5k/z1caxdLS7XHciyFOg10O1SVCdlX49iqY+Nghs4LJGkHyMUwRkIALnEEnHWruKTAM1ibwqj1TpC0tfJxjkDS74QZFWK7vnrU= --------=_MBD721955E-B167-414D-9B27-7112B546B004 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable When I had Tracy's 2.17 PSRU, I swung a 67 dia x 72 pitch prop. Climb=20 and cruise were fine but takeoff (especially from a short runway on a=20 hot day left something to be desired). When I got Tracy's 2.85 PSRU, I had a 76 x80 wood prop build by=20 Performance propellers. I flew a few times with it as such and while=20 performance was much better rpm was only around 5800. Plus the prop was=20 only a couple inches from the ground on my RV-6A Nose gear aircraft -=20 was concerned about landing of grass strips with possible mole holes. =20 So I had the diameter reduced to 74 Inches. That was what the doctor=20 ordered. There was a considerable difference in aircraft performance particularly=20 during take off. With the new combination, I had to tap the left brake=20 to keep runway alignment (if I cobbed full power from a standing start)=20 until airspeed reached approx 40 mph at which time the rudder authority=20 became adequate to hold the nose down the runway. Starting acceleration=20 was considerably better with the new combination, it literally push me=20 back in the seat. Climbout improved up to around 1700 fpm previous had=20 been around 1000 fpm. I had thought I would probably have to give up a few knots on the top=20 end, but it turned out I actually increased airspeed by approx 4 mph. =20 So it was really a win win for me. I could get up to around 6200-6250=20 WOT at cruise, so apparently at high airspeed the prop/gearbox unloaded=20 the engine to pick up a few more HP. It appears that for takeoff there is nothing better than the volume=20 (mass) of air your prop is able to push behind it. So even though the=20 prop turned slower with the 2.85, the much larger prop and the engine=20 increase from a take off rpm of around 56-5700 rpm to 6000 and the=20 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=20 the prop also turned in the conventional direction.=F0=9F=98=84 Ed ------ Original Message ------ From: "Charlie England ceengland7@gmail.com"=20 To: "Rotary motors in aircraft" 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=20 >prop diameters on RVs. Van started out recommending 68" dia props on=20 >the 2 seat RVs. My 1st RV4 had a Warnke 72x72. With 160 HP, it had=20 >1200-1500fpm climb and would cruise at 170 kts @ ~9.3 gph rich of peak,=20 >~75% power for a Lyc 160. The cruise matched Van's numbers, and climb=20 >was at least as good, if not better than Van's numbers. After my=20 >partner in the RV damaged the Warnke, I replaced it with a 68" from=20 >another mfgr and the plane never performed as well in either cruise or=20 >climb. At one point, I tried a 76" dia IVO. Climb was incredible, but=20 >the plane would hit a wall at about 145-150 kts (known problem with=20 >IVO's blades; they don't have enough twist for high speed operation).=20 >Another data point: Van's current catalog lists a Hartzel 74" dia c/s=20 >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=20 >yours. If you start with the Lyc-standard 2700 prop rpm, with the=20 >realization that 74" is not too large a diameter (for tip speed issues)=20 >at 2700, then the optimum ratio would be determined by your desired max=20 >engine rpm. With a controllable prop, you can give up a little bit in=20 >diameter & get back low speed thrust by going to flatter pitch & more=20 >HP. But if fixed pitch, I try for the largest dia I can safely fit on=20 >the plane. With a typical fast 2 seat homebuilt, gear leg length, not=20 >tip speed, will almost always be the limiting factor even at 2700+ rpm.=20 >The bigger the diameter, the better the low speed mass flow (thrust),=20 >and there will be little to no penalty at any cruise speed under the=20 >180-190 kt range (well above 200 mph). > >The above assumes a properly designed prop, of course. One reason to=20 >desire that 2.4-2.5:1 ratio is that it gets prop rpm where the prop=20 >carver is used to working, and we're much more likely to get a usable=20 >prop on 1st try if he's in familiar territory. If you tell him, say,=20 >200 HP @ 2700 prop rpm & cruise at 75% will be 170 kts, he'll likely be=20 >able to get it right, 1st try. If, on the other hand, you're telling=20 >him the same HP & speed, but you want, for instance, 76" dia & 2300=20 >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=20 >f/p or c/s (because low speed thrust will always improve with diameter=20 >increases), knowing that ground clearance will be a problem long before=20 >tip speed becomes an issue. If you haven't already bought the 72", I'd=20 >be asking them for a 76" if they'll sell you one and you can safely=20 >swing it on your plane. And be sure to tell them the actual rpm range=20 >where it will operate. Their 'stock' 72" for a Lyc will be sub-optimal=20 >turning in the ~2000 rpm range with a 2.85 drive, unless you intend to=20 >really flog the engine hard all the time & pour a lot of fuel through=20 >it. > >FWIW, > >Charlie > >On Tue, Oct 19, 2021 at 7:38 PM Stephen Izett stephen.izett@gmail.com=20 > wrote: >>Hi Andrew >> >>Continuing to fine tune the Renesis cooling system and aircraft. >>Completing a new exhaust system after a leaking gasket warped a=20 >>flange. >>Last flight temps max=E2=80=99d at 91C (196F) on takeoff with 20C (68F)OA= T and=20 >>we got her up to 189knots but only 2600 feet due to cloud. >>Learning that increasing the IAS by ~10knots in climb has a=20 >>significant effect on cooling. >> >>Also in the process of changing the current 66.5=E2=80=9D Airmasterto for = a=20 >>72=E2=80=9D MT prop. >>I only read after going with our gearbox/prop combination that Tracy=20 >>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=20 >>choose: >>1. Largest prop dimeter with acceptable clearance >>2. Target cruise tip speed of ~0.8-0.85 speed of sound for best=20 >>efficiency >>If this is correct then with a 72=E2=80=9D prop and a chosen engine redli= ne of=20 >>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 redlin= e. >> >>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=20 >>> wrote: >>> >>>Hi Steve, hows the Glasair going? I been away from flying for awhile,=20 >>>hopefully back into it in new year. Did start mine recently after it=20 >>>been sitting idle since feb 2020, So happy I persevered with the=20 >>>mazda, it started & ran so sweet I contemplated doing a couple of=20 >>>circuits but for the legalities. No MR and I need AFR first. >>> >>>Neil, not sure I agree with your rotor setup proposal, ( not that=20 >>>mine is better) can get some weird aerodynamics with intermeshing=20 >>>rotors. >>>Whole thing of nurse cart & drone need to be a package, rotors will=20 >>>never be stopped during refill so drone needs to land on roof of=20 >>>truck or trailer for refill from underneath to keep blades clear of=20 >>>dumbasses like me. >>>Truth be told, I dont think we can get anywhere near the efficiency=20 >>>of a ground rig or Ag plane, we easily average 80 ha/hr each machine=20 >>>+ nurse cart, going to need a swarm of drones to get near this. But=20 >>>could be a fun project. >>>Andrew >>> >>>On Tue, 19 Oct. 2021, 9:07 am Stephen Izett stephen.izett@gmail.com,=20 >>> wrote: >>>>Good to hear your voice Andrew. >>>>My son-in-law in Kojonup would be very interested in what you guys=20 >>>>are talking about. >>>> >>>>Cheers >>>> >>>>Steve Izett >>>> >>>>> >>>>>>> >>>>>>> >>>> >>>-- >>>Regards Andrew Martin Martin Ag >> --------=_MBD721955E-B167-414D-9B27-7112B546B004 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
When I had Tracy's 2.= 17 PSRU, I swung a 67 dia x 72 pitch prop.=C2=A0 Climb and cruise were fine = but takeoff (especially from a short runway on a hot day left something to = be desired).=C2=A0=C2=A0

When I got Tracy's 2.8= 5 PSRU, I had a 76 x80 wood prop build by Performance propellers.=C2=A0 I f= lew a few times with it as such and while performance was much better rpm w= as only around 5800.=C2=A0 Plus the prop was only a couple inches from the= ground on my RV-6A Nose gear aircraft - was concerned about landing of gras= s strips with possible mole holes.=C2=A0 So I had the diameter reduced to 7= 4 Inches.=C2=A0 That was what the doctor ordered.

There was a considerable difference in aircraft performance particularly= during take off.=C2=A0 With the new combination, I had to tap the left brak= e to keep runway alignment (if I cobbed full power from a standing start) u= ntil airspeed reached approx 40 mph at which time the rudder authority beca= me adequate to hold the nose down the runway.=C2=A0 Starting acceleration w= as considerably better with the new combination, it literally push me back= in the seat.=C2=A0 Climbout improved up to around 1700 fpm previous had bee= n around 1000 fpm.

I had thought I would probabl= y have to give up a few knots on the top end, but it turned out I actually= increased airspeed by approx 4 mph.=C2=A0 So it was really a win win for me= .=C2=A0 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 b= etter than the volume (mass) of air your prop is able to push behind it.=C2= =A0 So even though the prop turned slower with the 2.85, the much larger pr= op and the engine increase from a take off rpm of around 56-5700 rpm to 600= 0 and the increased torque pushed a much larger volume (mass) of air.
=

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

Ed

------ Original Message ------
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 pr= op diameters on RVs. Van started out recommending 68" dia props on the 2 se= at RVs. My 1st RV4 had a Warnke 72x72. With 160 HP, it had 1200-1500fpm cli= mb and would cruise at 170 kts=C2=A0@ ~9.3 gph rich of peak, ~75% power for = a Lyc 160. The cruise matched Van's numbers, and climb was at least as goo= d, 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 per= formed as well in either cruise or climb. At one point, I tried a 76" dia I= VO. Climb was incredible, but the plane would=C2=A0hit a=C2=A0wall at=C2=A0= about 145-150 kts (known problem with IVO's blades; they don't have enough= =C2=A0twist for high speed operation). Another data point: Van's current ca= talog 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 realiz= ation 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 & ge= t back low speed thrust by going to flatter pitch & more HP. But if fix= ed pitch, I try for the largest dia I can safely fit on the plane. With a t= ypical fast 2 seat homebuilt, gear leg length, not tip speed, will almost a= lways be the limiting factor even at 2700+ rpm. The bigger the diameter, th= e better the low speed mass flow (thrust), and there will be little to no p= enalty at any cruise speed under the 180-190 kt range (well above 200 mph).= =C2=A0

The above assume= s 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, an= d we're much more likely to get a usable prop on 1st try if he's in familia= r territory. If you tell him, say, 200 HP=C2=A0@ 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 wan= t, 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 bec= omes an issue. If you haven't already bought the 72", I'd be asking them fo= r 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 wi= th a 2.85 drive, unless you intend to really flog the engine hard all the t= ime & 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 t= o 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 w= e got her up to 189knots but only 2600 feet due to cloud.
Learnin= g that increasing the IAS by ~10knots in climb has a significant effect on= cooling.

Also in the process of changing the cur= rent 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 o= nly using the 2.85:1 with props of >=3D74=E2=80=9D
For those w= ith expertise in this area, is it true that we should choose:
1.= Largest prop dimeter with acceptable clearance
2. Target cruise t= ip 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 a= ir soon Andrew.

Steve


On 20 Oct 2021, a= t 7:52 am, Andrew Martin andrew@m= artinag.com.au <flyro= tary@lancaironline.net> wrote:

Hi Steve, hows the Glasair going? I been away from flying for awhil= e, hopefully back into it in new year. Did start mine recently after it bee= n sitting idle since feb 2020, So happy I persevered with the mazda, it sta= rted & ran so sweet I contemplated doing a couple of circuits but for t= he 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 rot= ors.
Whole thing of nurse cart & drone nee= d to be a package, rotors will never be stopped during refill so drone need= s to land on roof of truck or trailer for refill from underneath to keep bl= ades clear of dumbasses like me.
Truth be told, I do= nt think we can get anywhere near the efficiency of a ground rig or Ag plan= e, we easily average 80 ha/hr each machine + nurse cart, going to need a sw= arm 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@lancairon= line.net> wrote:
Good to hear your voic= e Andrew.
My son-in-law in Kojonup would be very interested in what you = guys are talking about.

Cheers

=
Steve Izett

=C2=A0



--
Regards Andrew Martin Martin Ag

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