VansAirForceForums  
Home > VansAirForceForums

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

- Today's Posts | Insert Pics


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

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 11-08-2018, 09:49 PM
Gt-401 Gt-401 is offline
 
Join Date: Oct 2012
Location: Wray CO
Posts: 74
Default Flap extension speeds for the Rocket.

Iíve got about 150 hrs on my new to me rocket since I got it a little over a year ago. I have been flying it with the same flap extension speed as the RV-4. Now that I am flying it IFR more and more, I am wondering if anyone has beefed up the flaps to allow for a higher extension speed. It sure would be nice if I could get approach flaps in at 100 or even 120 KTAS
Reply With Quote
  #2  
Old 11-09-2018, 07:28 AM
Mel's Avatar
Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
Posts: 10,124
Default

Flaps are the only control surfaces that get extended into the airstream and stay there. All other control surfaces extend into the airstream only momentarily. Flaps carry some pretty extreme loads. I wouldn't try expanding on the designer's limits without doing some extensive engineering.
__________________
Mel Asberry..DAR since last century
A&P/EAA Tech Counselor/Flight Advisor/Nat'l Test Pilot School
Specializing in Amateur-Built and Light-Sport Aircraft
<rvmel(at)icloud.com>
North Texas (8TA5)
RV-6 Flying since 1993, 172hp O-320, 3-Blade Catto (since 2003)
Legend Cub purchased 12/2017
FRIEND of the RV-1
Eagle's Nest Mentor
Recipient of Wright Brothers "Master Pilot" Award

Last edited by Mel : 11-09-2018 at 07:47 AM.
Reply With Quote
  #3  
Old 11-09-2018, 10:11 AM
F1Boss's Avatar
F1Boss F1Boss is offline
 
Join Date: Aug 2006
Location: Taylor Texas
Posts: 693
Default it's OK

You can drop the flaps about an inch at 120KIAS - just look at flap speeds on a C210 or similar - certain speeds are OK for various angles. Same applies here.

If you have the Rube Goldberg setup under the floor, you might need to change to the F1/RV8 style system to keep things from bending...that short length of 1/4" threaded rod might not survive, along with the actuator rods.
__________________
Best,
Mark

"Not everyone needs a Rocket. Some folks, however, shouldn't live life without one.
You know who you are."
Budd Davisson, 1997
Reply With Quote
  #4  
Old 11-09-2018, 10:16 AM
vetterman vetterman is offline
 
Join Date: Oct 2006
Location: TX
Posts: 39
Default Rocket

I assure you. It isnít a Rube Goldberg setup under the floor.
Reply With Quote
  #5  
Old 11-09-2018, 12:03 PM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 4,098
Default

I removed the Rube Goldberg mess under the floor and went with an RV-8 style primarily to address the poor geometry. In the process I reduced complexity and weight and as a bonus the existing linear actuator is now capable of exerting more force at the flap attachment points without bending or stalling. The Rocket flaps are smaller and have closer rib pitch than RV-4, so should be stiffer in torsion. All that said I have no idea where the LIMFAC is on this system but I've busted published limits from time to time without damage.
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI instalation in work
RV-8 - Flying
1940 Taylorcraft BL-65 -flying
Reply With Quote
  #6  
Old 11-09-2018, 06:46 PM
Gt-401 Gt-401 is offline
 
Join Date: Oct 2012
Location: Wray CO
Posts: 74
Default Is there a weak link built in?

Is there an intensional weak spot in the flap mechanism that is meant to bend or shear to keep from damaging more important parts, like for example a clutch on the motor, or maybe a breaker that would pop if to high a load was applied to the flaps? Leading to my next question, is the flap motor powerful enough to bend stuff if it is active at too high a speed?
Reply With Quote
  #7  
Old 11-09-2018, 07:46 PM
rocketbob's Avatar
rocketbob rocketbob is offline
 
Join Date: Jun 2006
Location: 8I3
Posts: 3,033
Default

My opinion is the weak point in the flap system is the torsional load on the main tube in the flap weldment. I believe the main tube would bend before anything breaks.

That said, I redesigned and implemented a "rube goldberg" flap drive completely hidden under the floor. "out of sight, out of mind."

The goal was to have no holes open in the floorboards which allow smoke and cold air to come in, and be easily accessible for maintenance.

I'd venture to guess its at least 3x more rigid than the stock RV-4/rocket setup. There are four spherical bushings supporting the main tube. The mechanical advantage of the linear actuator is also improved.

Titanium components were fabricated to keep the weight down.

If interested I can post a video of it in operation.
__________________
Bob Japundza CFI A&PIA
N55BC RV-6 borrowed, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.

Last edited by rocketbob : 11-10-2018 at 08:26 AM.
Reply With Quote
  #8  
Old 11-09-2018, 08:33 PM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 4,098
Default

Quote:
Originally Posted by rocketbob View Post
...If interested I can post a video of it in operation.
Post a link, please!

The "Rube Goldberg" aspect of the original design include (IMHO): transmitting a high load through 90 degrees of change using high friction nylon pillow blocks; a walking beam that has such poor bearing support that the linear actuator needs a nylon sliding support to keep the whole mess from carving an arc through the aluminum on the bottom of the fuselage; poor mechanical advantage on the too small torque tube; heavy, solid rod linkage in several places; and using stud mounted heim joints at the flaps instead of spacers and through bolts.

Other than that, its a great system!
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI instalation in work
RV-8 - Flying
1940 Taylorcraft BL-65 -flying
Reply With Quote
  #9  
Old 11-09-2018, 09:15 PM
rocketbob's Avatar
rocketbob rocketbob is offline
 
Join Date: Jun 2006
Location: 8I3
Posts: 3,033
Default

https://photos.app.goo.gl/AF5hgkqcfEKZebk7A
__________________
Bob Japundza CFI A&PIA
N55BC RV-6 borrowed, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
Reply With Quote
  #10  
Old 11-10-2018, 08:14 AM
smokyray's Avatar
smokyray smokyray is offline
 
Join Date: Jan 2005
Location: TX32
Posts: 1,748
Default Yours is not to question...

Quote:
Originally Posted by Gt-401 View Post
I’ve got about 150 hrs on my new to me rocket since I got it a little over a year ago. I have been flying it with the same flap extension speed as the RV-4. Now that I am flying it IFR more and more, I am wondering if anyone has beefed up the flaps to allow for a higher extension speed. It sure would be nice if I could get approach flaps in at 100 or even 120 KTAS
First answer: WHY? My manual flaps on my HR2 were extended at either half or full or "pilot's choice" by pressing the button and pulling slightly.
You might try your prop in a flatter pitch, different power setting and be happy with it.
As mentioned by Mel, Flaps get enough abuse as it is...adhere to the RV4 max extension speeds and they will last a long time...
V/R
Smokey
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 12:16 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.