VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-12
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Closed Thread
 
Thread Tools Search this Thread Display Modes
  #1  
Old 08-03-2017, 11:26 AM
AlanTN AlanTN is offline
 
Join Date: Apr 2011
Location: Linden, TN
Posts: 73
Default Which Range Numbers are Real?

Van's says about the RV-12: "It is what we say it is and does what we say it does, and we have the test data to prove it!"
I have two questions that perhaps Scott can answer:
1. There seems to be a significant disagreement between the range numbers previously posted for the RV-12 with the 912ULS, (which are 555 miles at 7500 feet and 5500 rpm and 614 miles at 7500 feet and 5000 rpm) and the currently posted numbers, (which are 433 miles at 7500 feet and 5500 rpm and 435 miles at 7500 feet and 5000 rpm). Which set of numbers actually matches the test data?
2. The numbers for the RV-12 with the 912iS are listed as 630 miles at 7500 feet and 5500 rpm and 605 miles at 7500 feet and 5000 rpm. Is it reasonable that flying with a lower power setting would actually reduce the range, and is there test data to support these numbers?
My thoughts about all this are that the original numbers for the RV-12 are probably correct, and the actual numbers for the RV-12iS are probably substantially higher than shown on Van's website. Can someone from Van's throw some light on this?
__________________
Alan Bishop
Mechanical Engineer
PPL since '66
  #2  
Old 08-03-2017, 11:29 AM
DaleB's Avatar
DaleB DaleB is offline
 
Join Date: Sep 2012
Location: Omaha, NE (KMLE)
Posts: 1,688
Default

For my 912ULS equipped RV-12 to get 555 miles, I'd need to be high enough I could glide the last hundred or so.
__________________
Dale
Omaha, NE
RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
Fisher Celebrity (under construction)
Previous RV-7 project (sold)
-=VAF=- 2017 dues paid
  #3  
Old 08-03-2017, 11:40 AM
Bruce Russell Bruce Russell is offline
 
Join Date: Jul 2008
Location: Clayton, GA
Posts: 175
Default

I agree with Dale. I have operated two different RV-12's with the 912ULS and 450 is the number.
__________________
Bruce Russell
Clayton, GA

Simultaneous Repeat Offender
  #4  
Old 08-03-2017, 11:43 AM
vic syracuse vic syracuse is offline
Super Moderator
 
Join Date: May 2005
Location: Locust Grove, GA
Posts: 2,005
Default

Yes, the new IS engine is actually about 25% MORE efficient at cruise power settings. There is even a detent on the throttle quadrant for the best economy position. At power settings less than that, it does become less fuel efficient than the UL engine.

Vic
__________________
Vic Syracuse

Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, DAR, A&P, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
EAA Homebuilt Council
Van's East Coast Representative
Mallards Landing, GA (GA04)
  #5  
Old 08-03-2017, 11:47 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 698
Default

Iíve never pushed it that far, but doing the math it looks like 450 is good with 3 gal remaining.

(17G/5GPH)130MPH = 442 Miles
__________________
-
Jim Stricker
Hinckley, Ohio
PPL - 1970
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC 7/12 Bought Flying 10/2015 with 48TT - Hobbs now 306
  #6  
Old 08-03-2017, 12:40 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 6,873
Default

Quote:
Originally Posted by AlanTN View Post
Van's says about the RV-12: "It is what we say it is and does what we say it does, and we have the test data to prove it!"
I have two questions that perhaps Scott can answer:
Not ignoring you, but Scott has learned not to answer questions that are presented in this manor.......
__________________
Any opinions expressed in this message are my own and not necessarily those of my employer.

Scott McDaniels
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
  #7  
Old 08-03-2017, 03:03 PM
AlanTN AlanTN is offline
 
Join Date: Apr 2011
Location: Linden, TN
Posts: 73
Default

Quote:
Originally Posted by rvbuilder2002 View Post
Not ignoring you, but Scott has learned not to answer questions that are presented in this manor.......
Scott, I do not mean any disrespect to you or to Van's. I am a Mechanical Engineer with some training in aircraft design and experience running a high speed wind test facility. I like Van's. I have been to this forum and Van's website hundreds of times over the last several years. I think the RV-12iS is a brilliant design.
As a prospective builder of this aircraft I just would like to know how the original data was derived and what has changed. The reason I used the quote is that it suggests to me that I can count on the numbers, and now they are not the same. Can you help me through this?
__________________
Alan Bishop
Mechanical Engineer
PPL since '66
  #8  
Old 08-03-2017, 04:00 PM
rgmwa rgmwa is offline
 
Join Date: Feb 2010
Location: Perth, Western Australia
Posts: 1,535
Default

The numbers listed in the POH (Rev 12) for the ULS are 482 nm at 7500'/5500rpm, and 534nm at 7500'/5000rpm. These equate to 555 and 614 statute miles respectively. It would be reasonable to expect the POH numbers to be correct.
__________________
rgmwa
120346
  #9  
Old 08-03-2017, 05:27 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 6,873
Default

Quote:
Originally Posted by AlanTN View Post
Scott, I do not mean any disrespect to you or to Van's. I am a Mechanical Engineer with some training in aircraft design and experience running a high speed wind test facility. I like Van's. I have been to this forum and Van's website hundreds of times over the last several years. I think the RV-12iS is a brilliant design.
As a prospective builder of this aircraft I just would like to know how the original data was derived and what has changed. The reason I used the quote is that it suggests to me that I can count on the numbers, and now they are not the same. Can you help me through this?
My (limited, I admit) understanding of the written English language is that when quotation marks are used it implies that that exact phrase has been heard used.

Yes, Van's does say that all published data is valid to the highest accuracy possible with no embellishment. and backed up with test results (and to the best we can it is), but I don't think it has every been said the way you quoted it (I bit snarky but I may have read something into it that wasn't intended).

Anyway, to answer your questions....

A lot of flight testing was recently done. Some with the ULS and iS prototypes flying side by side (climb tests while ballasted to same weights, cross country, etc).
The performance values currently on the web site and in the brochures are based on that testing.
The reason for differences when comparing to the previously publish data for the ULS airplane can not be established. The person who developed that data no longer woks at Van's and the used are inconclusive to determine where the error was induced. I am certain it was not intentional.

The reported reduced range at a slower engine speed is based on the test data available at this time (proof it is not being manipulated, since it doesn't totally make sense).
The iS airplane is still rather new. As more experience is gained perhaps an understanding will develop that will explain it, but it is likely related to the control software mapping for the engine.

As has already been published, the iS airplane, with the propeller pitch setting currently being used (which is .4 degrees courser that the setting on the ULS) climbs 100 FPM faster at Vy compared to the ULS (and at a higher RPM), when at the same weight.
The two airplanes flew together for the entire trip to OSH and back. With the iS airplane at the max. eco mode throttle setting and the ULS throttled to right at 5480-5500 RPM, the TAS is matched at 120 Kts but at the final fuel stop headed to OSH, the ULS airplane had used 60 Gal for the trip and the iS airplane had used 45 Gal.

Side note - All of the published range figures on the web site are absolute range (the point that you would run out of fuel).
It is taken for granted that pilots are (should be) capable of planning their own reserves with the FAA requirements.
__________________
Any opinions expressed in this message are my own and not necessarily those of my employer.

Scott McDaniels
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")

Last edited by rvbuilder2002 : 08-03-2017 at 05:33 PM. Reason: Added side note
  #10  
Old 08-03-2017, 07:58 PM
AlanTN AlanTN is offline
 
Join Date: Apr 2011
Location: Linden, TN
Posts: 73
Default

Scott, I copied and pasted the quote in question from the 3rd paragraph under the general information tab for the RV-12. It has been there for most, if not all of the time that the RV-12 has existed. I only used it because it speaks of 'test data' which support what the RV-12 is and does. And, obviously, the new numbers are dramatically different from those in the POH. Of course you don't know me, and written communications are always subject to misinterpretation, so I understand.

I am not totally sure what you are saying in the paragraph where the word 'differences' is used. If you could check what you said, perhaps it could be clearer. (I will edit this out)

It sounds like you are saying that the data in the Cruise Performance table in the POH based upon Van's flight tests of the RV-12 are not documented in writing in Van's records with dates, conditions and methods used. Is there adequate engineering documentation for all the other numbers supplied in the POH?
__________________
Alan Bishop
Mechanical Engineer
PPL since '66
Closed Thread


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 03:01 PM.


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.