Aerodynamics Discuss the physics of flight revolving around the aerodynamics and design of aircraft.

***** Seal This! *****

Reply

Old 02-25-2002, 11:30 PM
  #1  
LDaba
Senior Member
Thread Starter
My Feedback: (2)
 
LDaba's Avatar
 
Join Date: Feb 2002
Location: Queens, NY
Posts: 183
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default ***** Seal This! *****

I want to seal the gap of the control surfaces on my next project. I've heard that this will improve control efficiency. Do I reduce the recommended throws? And if so how much? Does anyone have experience with this method?Thanks in advance & Happy landings Tony
LDaba is offline  
Reply With Quote
Old 02-26-2002, 02:40 AM
  #2  
Mike James
Senior Member
 
Mike James's Avatar
 
Join Date: Jan 2002
Location: Anchorage, AK
Posts: 2,565
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Gap sealing

It's a great idea, unless your model is a scale project, and seals would make it look "wrong".

On sport/aerobatic planes I've built, flown without, then with seals, the difference was obvious from the first flight. I seal the surfaces on all my planes now. I wouldn't worry about reducing the throws until you fly it and see the difference.

You could:

1. Seal the gap with a bit of clear tape on the underside of the surfaces, or

2. Use Monokote, during the covering process, to seal the gaps, or

3. Run a thin bead of silicone into the gap

I've used all the above methods (more info on my web site) and they all work. I think you'll like the improved response, especially noticeable in roll rates.

Happy flying!
Mike James is offline  
Reply With Quote
Old 02-26-2002, 07:16 PM
  #3  
Jazzy
 
Join Date: Jan 2002
Location: Fort Walton Beach, FL
Posts: 1,217
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default ***** Seal This! *****

Is it noticable even if the gap is around 2mm or 1/16"?
I'm thinkin' about tryin' it.

Jeff

(Alright, 2mm is a bit much. Does 1mm sound better?)
Jazzy is offline  
Reply With Quote
Old 02-26-2002, 07:30 PM
  #4  
Mike James
Senior Member
 
Mike James's Avatar
 
Join Date: Jan 2002
Location: Anchorage, AK
Posts: 2,565
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Gaps

Every model is different, but on ALL of mine, sealing the gaps made the plane more responsive, and less prone to flutter.
Mike James is offline  
Reply With Quote
Old 02-26-2002, 08:23 PM
  #5  
Jazzy
 
Join Date: Jan 2002
Location: Fort Walton Beach, FL
Posts: 1,217
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default ***** Seal This! *****

Thanks. Will it reduce rudder flutter too? (Say that one really fast a couple times)
Sounds like this would be a good candidate for Tips & Techniques.
Something like: 'How To Reduce Flutter'.
Just a thought.

Jeff
Jazzy is offline  
Reply With Quote
Old 02-26-2002, 08:50 PM
  #6  
Chris300s
Senior Member
My Feedback: (1)
 
Join Date: Dec 2001
Location: Mount Clemens, MI
Posts: 309
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default ***** Seal This! *****

Mike is right on about the how to's.
I would estimate the response from gap sealing to increase 75% at full throttle and 150% at take off and landing. Gap seals are particularly effective at near stall velocities and high angles of attack.
You're dealing with areas of pressure so any gap will allow the pressure to equalize and reduce effectiveness. Additionally, large enough gaps may cause the airflow to separate resulting in loss of lift (tip stalling).
Gap seals may reduce flutter by reducing the turbulance over the surface, but not always. the biggest benefits of gap sealing are authority at landing and take off, increased roll rates and effectiveness in 3D. You'll have a machine that stalls slower, lifts off quick and responds much more crisply. The only downside is that your sluggich ailerons won't be hiding wing warps and binding linkages anymore. Many acro machines have enough authority to counter engine torque with the ailerons at 0 airspeed! On propwash alone they can roll right.
Chris300s is offline  
Reply With Quote
Old 02-26-2002, 09:10 PM
  #7  
Jazzy
 
Join Date: Jan 2002
Location: Fort Walton Beach, FL
Posts: 1,217
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default ***** Seal This! *****

Thanks guys.
After taking a moment to visualize in active 3 dimensions in my mind, I understand the how and why advantages of gap-sealing.
The pressure thing cued it all into place.

Thanks again,
Jeff
Jazzy is offline  
Reply With Quote
Old 02-27-2002, 02:28 AM
  #8  
LDaba
Senior Member
Thread Starter
My Feedback: (2)
 
LDaba's Avatar
 
Join Date: Feb 2002
Location: Queens, NY
Posts: 183
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default ***** Seal This! *****

Wow, what great info, thanks. I'm building a sport aerobatic plane and will definitely seal the control surface gap. The retained contol authority at lower speeds is a big plus.
Happy landings Tony
LDaba is offline  
Reply With Quote
Old 02-27-2002, 10:51 AM
  #9  
Cactus.
Senior Member
My Feedback: (1)
 
Cactus.'s Avatar
 
Join Date: Dec 2001
Location: CamborneCornwall, UNITED KINGDOM
Posts: 6,136
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default ***** Seal This! *****

I normally top hinge my surfaces, or side hinge on rudder, it gives me that seal and i can run tape along the top easily, if the hinge is already center hinged, then i get them as close as possible, i'd be horrorfied by a 2mm gap, you could post letters though that!
Its amazing how many of the fast planes on our field have had their flutter cured JUST by taping up the gaps, even if they are tiny
Cactus. is offline  
Reply With Quote
Old 02-27-2002, 01:48 PM
  #10  
Mark Hansen
Member
 
Join Date: Jan 2002
Location: Harwinton, CT
Posts: 32
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default ***** Seal This! *****

Using the silicon works - Just enought to seal the gap? Doesn't bind the action ? Mark
Mark Hansen is offline  
Reply With Quote

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

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service