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.






VAF on Twitter:
@VansAirForceNet


Go Back   VAF Forums > Main > Safety
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #11  
Old 08-17-2022, 12:07 PM
jrs14855 jrs14855 is offline
 
Join Date: Apr 2008
Location: Lake Havasu City AZ
Posts: 2,944
Default Poem

Aviation Courtesy starts out with a rather macabre poem about "Ace". If anyone remembers this being in Sport Aviation I would like to know.
Reply With Quote
  #12  
Old 08-17-2022, 12:44 PM
RV8JD's Avatar
RV8JD RV8JD is offline
 
Join Date: Jan 2005
Posts: 745
Default

Quote:
Originally Posted by jrs14855 View Post
For anyone with limited aerobatic experience planning aerobatics in an RV, Van's An Aerobatic Epistle is a must read. That also took me to a lengthy article by Van and others that was submitted for publication in Sport Aviation. I don't know if it was ever published. "Aviation Courtesy"
The difference between the aerobatic RV's when compared to many other aerobatic aircraft is the wider range between stall and Vne, Epistle details how easy it is to impose a load of 20 G's on an RV by yanking on the stick at or near Vne.
Links to several articles on RV aerobatics:

An article by Van himself, "An Aerobatic Epistle":
https://drive.google.com/file/d/16-I...ew?usp=sharing

Another article by Van himself on competition aerobatics, "IAC Aerobatics in RVs". It includes a good addendum on preparing your RV for aerobatics by Ron Schreck:
https://drive.google.com/file/d/1AGr...ew?usp=sharing

An article by Budd Davisson:
https://drive.google.com/file/d/1USX...ew?usp=sharing

And note the "Aerobatics" section on Van's website:
https://www.vansaircraft.com/flying-an-rv/
__________________
Carl N.
RV-8
KAWO
Reply With Quote
  #13  
Old 08-17-2022, 12:54 PM
rv8ch's Avatar
rv8ch rv8ch is offline
 
Join Date: Feb 2005
Location: LSGY
Posts: 5,116
Default

Quote:
Originally Posted by jrs14855 View Post
For anyone with limited aerobatic experience planning aerobatics in an RV, Van's An Aerobatic Epistle is a must read. That also took me to a lengthy article by Van and others that was submitted for publication in Sport Aviation. I don't know if it was ever published. "Aviation Courtesy"
The difference between the aerobatic RV's when compared to many other aerobatic aircraft is the wider range between stall and Vne, Epistle details how easy it is to impose a load of 20 G's on an RV by yanking on the stick at or near Vne.
I tool the liberty of stealing the excellent "Aviation Courtesy" article and reposting it on my website:

http://www.rv8.ch/aviation-courtesy/
__________________
Mickey Coggins

http://www.rv8.ch/help-people-in-ukraine/
Reply With Quote
  #14  
Old 08-17-2022, 02:46 PM
Roadjunkie1's Avatar
Roadjunkie1 Roadjunkie1 is offline
 
Join Date: Jun 2017
Location: Erie, Colorado
Posts: 415
Default

There was a post a while ago, possibly referring to a Kitplanes article, about the most common cause of RV-4 wings parting company with the airplane. As I remember, it was pilots newly acquiring an RV-4, not builders, that would execute a fast low pass with a zooming pull-up. Easy to overstress any airplane. The RV series is very responsive without being twitchy but even SMALL stick inputs can results in LARGE changes in attitude. Pull the stick back half an inch at cruise and see how fast you are suddenly at another altitude.

Ya'll be careful out there now.....
__________________
Michael
RV-4 2860 SuzieQ
1946 C-90-8 J-3 Cub
The adventure begins when things stop going as planned - Glen Heggstad
Exempt but still a happy Subscriber! 2022-2023
Reply With Quote
  #15  
Old 08-17-2022, 03:38 PM
RV8JD's Avatar
RV8JD RV8JD is offline
 
Join Date: Jan 2005
Posts: 745
Default

Quote:
Originally Posted by Roadjunkie1 View Post
There was a post a while ago, possibly referring to a Kitplanes article, about the most common cause of RV-4 wings parting company with the airplane. As I remember, it was pilots newly acquiring an RV-4, not builders, that would execute a fast low pass with a zooming pull-up. Easy to overstress any airplane. The RV series is very responsive without being twitchy but even SMALL stick inputs can results in LARGE changes in attitude. Pull the stick back half an inch at cruise and see how fast you are suddenly at another altitude.

Ya'll be careful out there now.....
The RV-7/7As are not coming apart in-flight because of wing failures.
__________________
Carl N.
RV-8
KAWO

Last edited by RV8JD : 08-17-2022 at 03:43 PM.
Reply With Quote
  #16  
Old 08-17-2022, 05:28 PM
RV8JD's Avatar
RV8JD RV8JD is offline
 
Join Date: Jan 2005
Posts: 745
Default

I believe the RV-7/7A is safe if it is operated strictly within Vanís operating envelope (airspeed, weight, and load factor limits), the rudder is properly balanced, and the jam nuts on the control surface hinges are always tight.

The problem appears to be that there are small rudder strength margins and small fin/rudder flutter margins outside that envelope when equipped with the -9/-7 rudder. Note that RV-8s are not coming apart in-flight with the same regularity and for the same reason that RV-7s are. And I don't think RV-8 pilots are any better or more careful than RV-7 pilots.

Based on the in-depth investigations of two RV-7s coming apart in-flight (by the Canadian and New Zealand safety authorities) and evidence of the others that have come apart in-flight, if I had an RV-7/7A it would have an RV-8 rudder on it instead of the RV-9 rudder that came with the kits since mid-2002. Note that the -9 rudder was designed for an airplane that has a Vne of 210 MPH, whereas the -7 has a Vne of 230 MPH. Now, of course, those speeds are designated as TAS values.

For the reasons given below, the -8 rudder would provide larger strength and flutter margins in case of an inadvertent excursion outside the published flight envelope:
- The -8 rudder has thicker skins (0.020") than the -9/-7 rudder (0.016"), making the -8 rudder stronger and stiffer.

- The -8 rudder has a folded trailing edge, which makes the -8 rudder stiffer and stronger than the riveted trailing edge of the -9/-7 rudder.

- The -8 rudder has less area than the -9/-7 rudder, creating smaller unsteady (oscillatory) aerodynamic forces (which are an important item in the flutter equation) than the larger -9/-7 rudder.
Part of the problem (but I don't believe it's the whole problem) may be that Van's has never issued a Service Bulletin or Service Letter for the older RV models (including the -7s) stating that Van's changed the definition of Vne from IAS to TAS. They did put out an SL for the RV-14, and they put out a POH revision for the RV-12s, but nothing for the older RVs. It's disappointing that Van's has not issued an SB or SL addressing their change of that critical safety-of-flight information. Many RV pilots are unaware that Vne is now in terms of TAS, instead of IAS. At higher altitudes RV pilots may operate above Vne without realizing it.

Van's did publish this article, "Flying High and Fast", on high horsepower and the concern about IAS vs TAS, flutter, and operating at higher altitudes. But it is not an acceptable substitute for an SB or SL for each model stating the new definition of Vne is in terms of TAS, since an SB or SL would reach a much wider audience of pilots and builders.

It does seem that more and more folks are putting -8 rudders on their -7s, and thatís a good thing, IMO.
__________________
Carl N.
RV-8
KAWO

Last edited by RV8JD : 01-15-2023 at 08:48 PM.
Reply With Quote
  #17  
Old 08-17-2022, 05:28 PM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 6,452
Default

I'd submit that 7s are not failing at all if built properly and flown within the prescribed limits.

Other RV types have had stab failures from coarse elevator input and wing failures too as I recall doing high speed stuff.

From a similar 2012 thread - "my suggestion would be to fly the plane within it's design limits- thousands of hours of "field testing" would suggest that the designs are pretty safe if you do that.
Terry, CFI
RV9A N323TP"
__________________

Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 462.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
https://www.youtube.com/channel/UCiy...g2GvQfelECCGoQ



Last edited by rv6ejguy : 08-17-2022 at 05:42 PM.
Reply With Quote
  #18  
Old 08-17-2022, 05:50 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 1,459
Default

Quote:
Originally Posted by RV8JD View Post

It does seem that more and more folks are putting -8 rudders on their -7s, and thatís a good thing, IMO.
If I had a -7, thatís what I would do.. especially because that -9 rudder feels just too big and stiff. Those folded trailing edges feel sweeter. Isnít the vertical different too? Like the -7 crowd would need to change the stab and the rudder together? I thought the -8 balance tab was smaller and doesnít fit the -7 stab..
__________________
Tom
Las Vegas
RV-4 flyingÖ
RV-8 empenage finished 10-2020

Wings Started.. 11-2020
Reply With Quote
  #19  
Old 08-17-2022, 05:54 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 8,699
Default

Quote:
Originally Posted by RV8JD View Post

Part of the problem (but I don't believe it's the whole problem) may be that Van's has never issued a Service Bulletin or Service Letter for the older RV models (including the -7s) stating that Van's changed the definition of Vne from IAS to TAS. They did put out an SL for the RV-14, and they put out a POH revision for the RV-12s, but nothing for the older RVs. It's disappointing that Van's has not issued an SB or SL addressing their change of that critical safety-of-flight information. Many RV pilots are unaware that Vne is now in terms of TASÖ
+1. Since this is so different from the way normal (part 23) aircraft limitations are expressed, I too am disappointed in the way this information has (or has not) been disseminated. IMHO itís a black mark for an otherwise excellent company.
Reply With Quote
  #20  
Old 08-17-2022, 06:04 PM
N942R N942R is offline
 
Join Date: May 2010
Location: Taylor, AZ
Posts: 38
Default

The RV 7 rudder is originally designed for the rv9 which has a significantly lower maneuvering and VNE speeds...
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 02:33 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.