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 [47.43.26.132] (HELO p-impout001.msg.pkvw.co.charter.net) by logan.com (CommuniGate Pro SMTP 6.3.5) with ESMTPS id 378632 for flyrotary@lancaironline.net; Thu, 21 Oct 2021 10:38:01 -0400 Received-SPF: pass receiver=logan.com; client-ip=47.43.26.132; envelope-from=eanderson@carolina.rr.com Received: from [127.0.0.1] ([66.26.212.217]) by cmsmtp with ESMTP id dZCQmT2X8ciyGdZCRmwj0E; Thu, 21 Oct 2021 14:37:43 +0000 X-Authority-Analysis: v=2.4 cv=GPfNrsBK c=1 sm=1 tr=0 ts=61717b37 a=WcvdwKkRgKsaRaJ9Bx4DbQ==:117 a=WcvdwKkRgKsaRaJ9Bx4DbQ==:17 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=ayC55rCoAAAA:8 a=eRLigfuSAAAA:8 a=2UDvpDbrmzFmwC-BIFoA:9 a=QEXdDO2ut3YA:10 a=4PR2P7QzAAAA:8 a=HIh0QKzSHmp5pnBNKxsA:9 a=7bvK6i6Syqau-voh:21 a=frz4AuCg-hUA:10 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=B_RyunTPg8udlmYm5Cu2:22 a=BfhXYjFvZD4iae-mNffo:22 a=4dqwQCo7Po2mVW515mGf:22 To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Props and gear boxes Date: Thu, 21 Oct 2021 14:37:42 +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="------=_MB99547E41-5F0C-4E73-BA63-08DB127B8E96" X-CMAE-Envelope: MS4xfP9SYCtoqd9n6IwsSuqpQoJccUdUwzSozfar6zbLqmf3EJj4qpKq9fgYv+Ezcg0/S81r4G/t7aclW8ZSSAA8NCmgI+xiwZ0j4baVSH1Rf+8eKBb8xuaS qNQyy9TgVcwN3kOb/c8RI1H/al5MOOCR5QshHGcajOGYYmAPnckSV8zvVpz4Mix1yWN+5SkWgKx2YeI3vLWDM/Fsti6RfYlZp3I= --------=_MB99547E41-5F0C-4E73-BA63-08DB127B8E96 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Clearance for a RV-xA would probably vary a bit. But in my case with a 74" dia prop (cut down from 76) I had 4-5"=20 clearance depending on fuel/passenger/baggage load. I did tend to keep=20 the stick back on my belly button whenever taxing especially on=20 non-paved areas. Mostly make full flair landings with nose gear=20 touching after main gear. Made it a point not to keep the nose gear off=20 too long to preclude it from slamming down as airspeed died off. Ed ------ Original Message ------ From: "Stephen Izett stephen.izett@gmail.com"=20 To: "Rotary motors in aircraft" Sent: 10/20/2021 3:50:29 PM Subject: [FlyRotary] Re: Props and gear boxes >Thanks for the real prop knowledge and feedback Charlie and Ed. > >Ground clearance is another area I=E2=80=99m left wondering about after he= aring=20 >what Charlie has played with. >I think I=E2=80=99ll have just over 6.7 inches when the 72=E2=80=9D MT goe= s on. I=20 >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=20 >> wrote: >> >>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=20 >>was only a couple inches from the ground on my RV-6A Nose gear=20 >>aircraft - was concerned about landing of grass strips with possible=20 >>mole holes. So I had the diameter reduced to 74 Inches. That was=20 >>what the doctor ordered. >> >>There was a considerable difference in aircraft performance=20 >>particularly during take off. With the new combination, I had to tap=20 >>the left brake to keep runway alignment (if I cobbed full power from a=20 >>standing start) until airspeed reached approx 40 mph at which time the=20 >>rudder authority became adequate to hold the nose down the runway. =20 >>Starting acceleration was considerably better with the new=20 >>combination, it literally push me back in the seat. Climbout improved=20 >>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=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=20 >>unloaded 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,=20 >>now 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=20 >>>various prop diameters on RVs. Van started out recommending 68" dia=20 >>>props on the 2 seat RVs. My 1st RV4 had a Warnke 72x72. With 160 HP,=20 >>>it had 1200-1500fpm climb and would cruise at 170 kts @ ~9.3 gph rich=20 >>>of peak, ~75% power for a Lyc 160. The cruise matched Van's numbers,=20 >>>and climb was at least as good, if not better than Van's numbers.=20 >>>After my partner in the RV damaged the Warnke, I replaced it with a=20 >>>68" from another mfgr and the plane never performed as well in either=20 >>>cruise or climb. At one point, I tried a 76" dia IVO. Climb was=20 >>>incredible, but the plane would hit a wall at about 145-150 kts=20 >>>(known problem with IVO's blades; they don't have enough twist for=20 >>>high speed operation). Another data point: Van's current catalog=20 >>>lists a Hartzel 74" dia c/s prop for the 2 seat a/c and the f/p props=20 >>>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=20 >>>issues) at 2700, then the optimum ratio would be determined by your=20 >>>desired max engine rpm. With a controllable prop, you can give up a=20 >>>little bit in diameter & get back low speed thrust by going to=20 >>>flatter pitch & more HP. But if fixed pitch, I try for the largest=20 >>>dia I can safely fit on the plane. With a typical fast 2 seat=20 >>>homebuilt, gear leg length, not tip speed, will almost always be the=20 >>>limiting factor even at 2700+ rpm. The bigger the diameter, the=20 >>>better the low speed mass flow (thrust), and there will be little to=20 >>>no penalty at any cruise speed under the 180-190 kt range (well above=20 >>>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=20 >>>be able to get it right, 1st try. If, on the other hand, you're=20 >>>telling him the same HP & speed, but you want, for instance, 76" dia=20 >>>& 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=20 >>>f/p or c/s (because low speed thrust will always improve with=20 >>>diameter increases), knowing that ground clearance will be a problem=20 >>>long before tip speed becomes an issue. If you haven't already bought=20 >>>the 72", I'd be asking them for a 76" if they'll sell you one and you=20 >>>can safely swing it on your plane. And be sure to tell them the=20 >>>actual rpm range where it will operate. Their 'stock' 72" for a Lyc=20 >>>will be sub-optimal turning in the ~2000 rpm range with a 2.85 drive,=20 >>>unless you intend to really flog the engine hard all the time & pour=20 >>>a lot of fuel through 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)= OAT=20 >>>>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=20 >>>>significant effect on cooling. >>>> >>>>Also in the process of changing the current 66.5=E2=80=9D Airmasterto f= or 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 red= line=20 >>>>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 redl= ine. >>>> >>>>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=20 >>>>>awhile, hopefully back into it in new year. Did start mine recently=20 >>>>>after it been sitting idle since feb 2020, So happy I persevered=20 >>>>>with the mazda, it started & ran so sweet I contemplated doing a=20 >>>>>couple of circuits but for the legalities. No MR and I need AFR=20 >>>>>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=20 >>>>>machine + nurse cart, going to need a swarm of drones to get near=20 >>>>>this. But could be a fun project. >>>>>Andrew >>>>> >>>>>On Tue, 19 Oct. 2021, 9:07 am Stephen Izett=20 >>>>>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=20 >>>>>>are talking about. >>>>>> >>>>>>Cheers >>>>>> >>>>>>Steve Izett >>>>>> >>>>>>> >>>>>>>>> >>>>>>>>> >>>>>> >>>>>-- >>>>>Regards Andrew Martin Martin Ag > --------=_MB99547E41-5F0C-4E73-BA63-08DB127B8E96 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Clearance for a RV-xA = would probably vary a bit.=C2=A0=C2=A0

But in m= y case with a 74" dia prop (cut down from 76) I had 4-5" clearance dependin= g on fuel/passenger/baggage load.=C2=A0 I did tend to keep the stick back o= n my belly button whenever taxing especially on non-paved areas.=C2=A0 Most= ly make full flair landings with nose gear touching after main gear.=C2=A0= Made it a point not to keep the nose gear off too long to preclude it from= slamming down as airspeed died off.

Ed

------ Original Message ------
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: 10/20/2021 3:50:29 PM
Subject: [FlyRotary] Re: Props and gear boxes

Thanks for the real prop knowledge and feedback Charlie and Ed.

Ground clearance is another ar= ea I=E2=80=99m left wondering about after hearing what Charlie has played w= ith.
I think I=E2=80=99ll have just over 6.7 inches wh= en 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 Ize= tt






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

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 2.85 PSRU, I had a 76 x= 80 wood prop build by Performance propellers.=C2=A0 I flew a few times with = it as such and while performance was much better rpm was only around 5800.= =C2=A0 Plus the prop was only a couple inches from the ground on my RV-6A N= ose gear aircraft - was concerned about landing of grass strips with possib= le mole holes.=C2=A0 So I had the diameter reduced to 74 Inches.=C2=A0 That = was what the doctor ordered.

There was a considerable difference in aircraft performance parti= cularly during take off.=C2=A0 With the new combination, I had to tap the l= eft 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 author= ity became adequate to hold the nose down the runway.=C2=A0 Starting accele= ration was 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 been around 1000 fpm.

I had thought I would probably have to give up a few knots on the to= p 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 unloade= d 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.=C2=A0 So eve= n 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 conventi= onal direction.=F0=9F=98=84

Ed

------ Or= iginal Message ------
From: "Charlie England=C2=A0ceengland7@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 expertis= e, but I do have some experience with various prop diameters on RVs. Van st= arted out recommending 68" dia props on the 2 seat RVs. My 1st RV4 had a Wa= rnke 72x72. With 160 HP, it had 1200-1500fpm climb and would cruise at 170= kts=C2=A0@ ~9.3 gph rich of peak, ~75% power for a Lyc 160. The cruise matc= hed 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 cr= uise or climb. At one point, I tried a 76" dia IVO. Climb was incredible, b= ut the plane would=C2=A0hit a=C2=A0wall at=C2=A0about 145-150 kts (known pr= oblem with IVO's blades; they don't have enough=C2=A0twist for high speed o= peration). Another data point: Van's current catalog lists a Hartzel 74" di= a c/s prop for the 2 seat a/c and the f/p props are in the 72" dia range.

My calcul= ations 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 opti= mum ratio would be determined by your desired max engine rpm. With a contro= llable prop, you can give up a little bit in diameter & get back low sp= eed thrust by going to flatter pitch & more HP. But if fixed pitch, I t= ry 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).=C2=A0
<= div class=3D"gmail_default" style=3D"font-size: small;">
The above assu= mes 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 famil= iar territory. If you tell him, say, 200 HP=C2=A0@ 2700 prop rpm & crui= se at 75% will be 170 kts, he'll likely be able to get it right, 1st try. I= f, on the other hand, you're telling him the same HP & speed, but you w= ant, for instance, 76" dia & 2300 prop rpm, he's going to be guessing o= n how to carve the prop.

Bottom line: I fit the largest dia I can safely swing, reg= ardless of f/p or c/s (because low speed thrust will always improve with di= ameter increases), knowing that ground clearance will be a problem long bef= ore 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 i= t on your plane. And be sure to tell them the actual rpm range where it wil= l 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 engi= ne hard all the time & pour a lot of fuel through it.

FWIW,

Charlie
On Tue, Oct 19, 2021 at 7:38 PM Stephen Izett=C2=A0stephen.izett@gmail.com=C2=A0<= /span><flyrota= ry@lancaironline.net> wrote:
Hi Andrew<= div class=3D"">
Continuing to fine tu= ne 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 af= ter going with our gearbox/prop combination that Tracy recommended only usi= ng the 2.85:1 with props of >=3D74=E2=80=9D
For tho= se 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 eff= iciency
If this is correct then with a 72=E2=80=9D pro= p 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 suit= ed 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 M= artin=C2=A0andrew@martinag.com.au=C2=A0<flyrotary@lancaironline.net> wrote:
<= /div>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 s= itting idle since feb 2020, So happy I persevered with the mazda, it starte= d & 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 yo= ur rotor setup proposal, ( not that mine is better) can get some weird aero= dynamics with intermeshing rotors.
= Whole thing of nurse cart & drone need to be a package, rotors will nev= er be stopped during refill so drone needs to land on roof of truck or trai= ler for refill from underneath to keep blades clear of dumbasses like me.
Truth be told, I dont think we can get any= where 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 ne= ar this. But could be a fun project.
Andr= ew

On = Tue, 19 Oct. 2021, 9:07 am Stephen Izett=C2=A0stephen.izett@gmail.com, <fly= rotary@lancaironline.net> wrote:
Good t= o hear your voice Andrew.
My son-in-law in Kojonup would be= very interested in what you guys are talking about.
Cheers

Steve Izett
<= br class=3D"" />
=C2=A0


=
=
--=C2=A0
Regards Andrew Martin Martin Ag

--------=_MB99547E41-5F0C-4E73-BA63-08DB127B8E96--