VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.


Go Back   VAF Forums > Model Specific > RV-8/8A
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #11  
Old 11-19-2021, 09:39 AM
Dan 57's Avatar
Dan 57 Dan 57 is offline
 
Join Date: Sep 2018
Location: LSZF
Posts: 963
Default

would I buy a car with only one gear? Think not...
Having a total performance RV with a speed ratio of 3.67 (factory figure for the 180HP version) and a FP prop just doesn't do justice to the design. Guess financing a every square inch available glass panel was prioritised, choices choices
__________________
- ain't the Destination, but the Journey -

www.aerofun.ch

RV-6.9 #25685, slider, O-360-A3A (carb/dual Lightspeed II), MTV-12-B, HB-YLL owner & lover
RV-4 #2062 HB-YVZ airframe builder
Reply With Quote
  #12  
Old 11-19-2021, 10:12 AM
Ralph Inkster Ralph Inkster is offline
 
Join Date: Feb 2008
Location: Calgary, Alberta
Posts: 1,773
Default

Quote:
Originally Posted by YvesCH View Post
My specs are:

Engine: Superior IO-360-M2S with dual PMag

Prop: Catto 3 blade, 68" diameter, 76" pitch

75% Power:
@3000ft: 2510rpm / IAS 156kts / TAS 165kts / 24.4" MP / 8.9 usg/hr
@6000ft: 2610rpm / IAS 159kts / TAS 174kts / 22.8" MP / 9.1 usg/hr

55% Power:
@3000ft: 2220rpm / IAS 136kts / TAS 144kts / 20.1" MP / 6.8 usg/hr
@6000ft: 2220rpm / IAS 134kts / TAS 152kts / 19.1" MP / 7.1 usg/hr

Those are measured values of my flight testing... But not yet lean of peak.

Then also the climb performance as well as takeoff and landing performance. But they were done when I did not yet had to much experience (below 30 T/O and LDGs in total) thus they may could be improved.


Regards,

Yves Heller
I think Yves gave an excellent response (including documented results) to the original posters question.

But the question begs asking "What is CRUISE speed?" when applying it to a fixed pitch prop. Is it W/O throttle, Partial throttle, % power, max rpm at ? altitude?? Seems everyone has a different definition of what CRUISE is.
__________________
Ralph
built a few RVs, rebuilt a few more, hot rodded more, & maintained/updated a big bunch more

Last edited by Ralph Inkster : 11-19-2021 at 02:14 PM.
Reply With Quote
  #13  
Old 11-19-2021, 11:31 AM
YvesCH YvesCH is offline
 
Join Date: Feb 2015
Location: Basel, Switzerland
Posts: 254
Default

Thanks Ralph.

Yes its somehow important that we all talk about the same thing to compare.
Such as is speed messured in mph or kts and indicated or true? And also as you mentioned at what setting.. Otherwise its quite difficult to compare.
__________________
-----------------------------------
Yves - Basel, Switzerland
RV-8 #83458 HB-YUA
Donation 2020 done
Reply With Quote
  #14  
Old 11-19-2021, 07:21 PM
David Z David Z is offline
 
Join Date: Aug 2010
Location: Thunder Bay Ontario
Posts: 892
Default

A properly pitched FP prop for top speed or other specific configuration has two advantages. Weight is the obvious one, and no prop governor. I'm sure the governor isn't taking huge amounts of power, but it's not zero either. It would be interesting to know it's exact requirement.
__________________
RV8
Empennage Passed Pre-close Inspection
Wings mostly done
Fuselage assembly, it's a riveting job!
83126
Dash 8 day job is financing the RV8
Donation till September 2022
Reply With Quote
  #15  
Old 11-20-2021, 07:15 AM
Scott Hersha Scott Hersha is offline
 
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 2,208
Default

Actual cruise numbers: RV4 rather than RV8, but relatively similar - O-360, standard compression, fixed pitch Sensenich carbon fiber prop pitched for 2700 at wide open throttle, so cruise setting I guess. In the pic below, 2560 RPM, 19.7”, 64% power, 9,500 feet, 8.8 gph, 172 KTAS. This is not at wide open throttle. WOT at this altitude would still give me 2700 RPM.

Click image for larger version

Name:	24DF0CE3-4C1F-4600-BEA3-9536772D081F.jpg
Views:	236
Size:	358.0 KB
ID:	18489
__________________
SH
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019/sold2021
RV6/Used kit purchased 2021 building
Cincinnati, OH/KHAO
JAN2022

Last edited by Scott Hersha : 11-20-2021 at 07:19 AM.
Reply With Quote
  #16  
Old 12-02-2021, 07:57 AM
PhatRV PhatRV is offline
 
Join Date: Mar 2018
Location: Buena Park, California
Posts: 785
Default

Quote:
Originally Posted by Scott Hersha View Post
Actual cruise numbers: RV4 rather than RV8, but relatively similar - O-360, standard compression, fixed pitch Sensenich carbon fiber prop pitched for 2700 at wide open throttle, so cruise setting I guess. In the pic below, 2560 RPM, 19.7”, 64% power, 9,500 feet, 8.8 gph, 172 KTAS. This is not at wide open throttle. WOT at this altitude would still give me 2700 RPM.

Attachment 18489
I can't wait to fly my to be finished RV8. The flight school rental barely files faster than 100kts.
__________________
RV8 standard build: 90% completed (90% to go)
Waiting to install wings to fuselage.
Days to Final Installation: 999
Days to AWC: 999
Days to First Flight: 999

Donation paid through 2022
Reply With Quote
  #17  
Old 12-02-2021, 12:21 PM
gasman gasman is offline
 
Join Date: Mar 2007
Location: Sonoma County
Posts: 4,346
Default

Quote:
Originally Posted by David Z View Post
A properly pitched FP prop for top speed or other specific configuration has two advantages. Weight is the obvious one, and no prop governor. I'm sure the governor isn't taking huge amounts of power, but it's not zero either. It would be interesting to know it's exact requirement.
Also, a C/S prop is the most expensive single item on your aircraft to maintain, if maintained i.a.w. the manufacturer.
__________________
VAF #897 Warren Moretti
2021 =VAF= Dues PAID
Reply With Quote
  #18  
Old 12-02-2021, 12:24 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 2,175
Default Yup

Quote:
Originally Posted by gasman View Post
Also, a C/S prop is the most expensive single item on your aircraft to maintain, if maintained i.a.w. the manufacturer.
Yup, this is why I went with fixed pitch Catto. Except for showing off on climb out, my flying doesnt entail 500 foot strips with 150’ trees at each end. But I am sure once I visit Johnson Creek with my new plane, that will change. ( Bring on the -15!)
__________________
John S

WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

Dues paid 2022, worth every penny

RV9A- Status:
98% done, 2% left to go
Structure done (less gear)
Electrical/Panel done
Firewall Forward 95% done
Fiberglass 70%
www.pilotjohnsrv9.blogspot.com
Reply With Quote
  #19  
Old 12-03-2021, 06:11 PM
brad walton brad walton is offline
 
Join Date: Jul 2007
Location: Cypress, TX
Posts: 538
Default

Cross country cruise in RV8 with Superior IO360 and Catto 3 blade I get 162 ktas at 2460 rpm and 8.2 gph at 5000 density altitude. 2700 rpm equals 178 ktas, more if I'm willing to exceed 2700 rpm. First photo is 178 ktas at 16000 density altitude. Second shows 30 + statute mpg at about 12000 density altitude. Don't buy the one gear thing. My turf airfield is at 155 feet msl and when I'm light, I can go from standstill to 1500 feet in one minute, more when temps are cool and less in hot summer temps
Attached Thumbnails
Click image for larger version

Name:	0620141308a.jpg
Views:	101
Size:	368.2 KB
ID:	19073  Click image for larger version

Name:	0620141322.jpg
Views:	90
Size:	274.3 KB
ID:	19074  

Last edited by brad walton : 12-03-2021 at 06:22 PM.
Reply With Quote
  #20  
Old 12-03-2021, 08:05 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 1,146
Default

Quote:
Originally Posted by brad walton View Post
Cross country cruise in RV8 with Superior IO360 and Catto 3 blade I get 162 ktas at 2460 rpm and 8.2 gph at 5000 density altitude. 2700 rpm equals 178 ktas, more if I'm willing to exceed 2700 rpm. First photo is 178 ktas at 16000 density altitude. Second shows 30 + statute mpg at about 12000 density altitude. Don't buy the one gear thing. My turf airfield is at 155 feet msl and when I'm light, I can go from standstill to 1500 feet in one minute, more when temps are cool and less in hot summer temps
What do you mean “Don’t buy the one gear thing”? Are you talking about fixed pitch props fly like you only have one gear? Because they do! A CS prop totally transforms the plane! It climbs better and lands shorter, and makes formation much easier.. but fixed or CS, they all cruise fast and are a blast to fly either way, but don’t knock CS on the RV.. it’s really the way to go on a -8 imo.
__________________
Tom
Las Vegas
RV-4 flying…
RV-8 empenage finished 10-2020

Wings Started.. 11-2020
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 05:37 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.