VansAirForceForums  
Home > VansAirForceForums

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

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-7/7A
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-03-2018, 11:52 PM
mfleming's Avatar
mfleming mfleming is online now
 
Join Date: Sep 2016
Location: Joseph, Oregon
Posts: 127
Question WD-409 Tailspring weldment Fit Problem

The WD-409 tail spring weldment on my Quick Build fuselage is not fitting very well.

Having to shim the WD-409 seems to be a common solution to having a gap between the bulkheads and the weldment.

My fit problem doesn't seem to be able to be fixed with a shim (maybe).

What I'm seeing is that the F-712 aft most bulkhead is concave.

The weldment flange fits up hard against the aft bulkhead in the center of the flange but there is a significant gap on either side of center. I checked the flatness of the F-712 bulkhead with a straightedge and sure enough, its off by the same amount as the gaps.

I suppose I could remove the bulkhead and try and flatten it out somehow and then add a shim.

Any thoughts would be appreciated.

Here's a photo of the situation:

__________________
Michael Fleming
Joseph, OR
sagriver at icloud dot com

RV-7 Slider #74572
Empennage (sans fiberglass)
Ailerons and flaps complete.
Wings done (sans fiberglass)
Started on QB fuselage
Donated 2017
Reply With Quote
  #2  
Old 02-04-2018, 05:31 AM
AndyWW AndyWW is online now
 
Join Date: Jan 2015
Location: Englefield Green UK
Posts: 48
Default

I have almost exactly the same problem! Mine is slow build, but the problem (at least for me) seems to actually be the WD-409 and not the bulkhead or aft fuselage geometry. Try carefully measuring the weldment and check that the aft face is parallel to the forward face. In my case, it isn't and the problem is with the aft face (twisted about 3/64"). It is also rotated slightly so that when the vertical hole through the weldment is exactly vertical the aft face isn't quite vertical (again the error seems to be about 3/64" measured on the top edge).

I have exchanged some emails with Van's and my current plan is to get the weldment straightened by a local welder, although Van's said it was ok to use shims at the aft end to make it fit correctly.
__________________
Andy @ EGLM/EGTB
RV-6 (Shared, Bought Flying)
Building RV-7 #74424
Starting fuselage
Donated 2018
Reply With Quote
  #3  
Old 02-04-2018, 08:44 AM
F1Boss's Avatar
F1Boss F1Boss is offline
 
Join Date: Aug 2006
Location: Taylor Texas
Posts: 638
Default Shim!

Looks like the aft bulkhead is not flat - might take it off and make sure it is, then shim as required. I ask folks to add a permanent fastener in the middle of the aft bulkhead fastener pattern - use a c/s head #10 screw so the fin spar still lays flat on the bulkhead when attached. If the ship is moved without the fin being fastened in place, the aft fuselage can be damaged, and this extra fastener will keep the damage from happening.

Looks like good work to me - keep it up!
__________________
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 02-04-2018, 08:58 AM
Bob Martin's Avatar
Bob Martin Bob Martin is offline
 
Join Date: Jan 2005
Location: Richmond, Virginia
Posts: 1,024
Default yes

[quote=F1Boss;1237016]I ask folks to add a permanent fastener in the middle of the aft bulkhead fastener pattern - use a c/s head #10 screw so the fin spar still lays flat on the bulkhead when attached. If the ship is moved without the fin being fastened in place, the aft fuselage can be damaged, and this extra fastener will keep the damage from happening.[quote]

I had this exact thing happen to me....had to replace the rear bulkheads!! Should be part of the plans.
__________________
Bob Martin
RV-6, 0-360 Hartzell C/S, Tip up, 1150+TT
James extended cowl/plenum, induction, -8VS and Rudder. TSFlightline hoses. Oregon Aero leather seats.
D100-KMD150-660-TT ADI2- AS air/oil seperator. Vetterman exhaust with turndown tips.
Louisa, Virginia KLKU N94TB
Reply With Quote
  #5  
Old 02-04-2018, 09:39 AM
mfleming's Avatar
mfleming mfleming is online now
 
Join Date: Sep 2016
Location: Joseph, Oregon
Posts: 127
Default

Quote:
Originally Posted by F1Boss View Post
.......... add a permanent fastener in the middle of the aft bulkhead fastener pattern - use a c/s head #10 screw so the fin spar still lays flat on the bulkhead when attached. If the ship is moved without the fin being fastened in place, the aft fuselage can be damaged, and this extra fastener will keep the damage from happening.
Interesting...not sure I understand exactly what you mean? Could you explain further or post a photo?
__________________
Michael Fleming
Joseph, OR
sagriver at icloud dot com

RV-7 Slider #74572
Empennage (sans fiberglass)
Ailerons and flaps complete.
Wings done (sans fiberglass)
Started on QB fuselage
Donated 2017
Reply With Quote
  #6  
Old 02-04-2018, 09:42 AM
mfleming's Avatar
mfleming mfleming is online now
 
Join Date: Sep 2016
Location: Joseph, Oregon
Posts: 127
Default

As an aside...
I have seen builders adding shims between the WD-409 and the F-712 aft bulkhead.
The plans say to add a shim, if needed, between the WD-409 and the F-711 bulkhead.
Any real reason to put the shim in one place or the other?
__________________
Michael Fleming
Joseph, OR
sagriver at icloud dot com

RV-7 Slider #74572
Empennage (sans fiberglass)
Ailerons and flaps complete.
Wings done (sans fiberglass)
Started on QB fuselage
Donated 2017
Reply With Quote
  #7  
Old 02-04-2018, 10:07 AM
Bob Martin's Avatar
Bob Martin Bob Martin is offline
 
Join Date: Jan 2005
Location: Richmond, Virginia
Posts: 1,024
Default

Quote:
Originally Posted by mfleming View Post
Interesting...not sure I understand exactly what you mean? Could you explain further or post a photo?
"If the ship is moved without the fin being fastened in place, the aft fuselage can be damaged, and this extra fastener will keep the damage from happening."

Think ahead: Once the plane is completed. If you removed the VS. The bolts holding the tailspring weldmont to the rear bulkhead are also removed. At that point the weldmont is carrying the weight of the tail and is pushing up on the hole cutout in the rear bulkhead, a point load! and the rear bulkhead will tear/deform/fail, while sitting in your hangar!
Now, if you remember to reinstall the bolts back into the bulkhead through the weldmont, that will also keep the problem from occuring. But it is easy to forget or not see the problem coming...ask me how I know
What Mark is saying, is to preemptivly install a screw through the rear bulkhead into the weldmont to possibly save yourself a future problem.
__________________
Bob Martin
RV-6, 0-360 Hartzell C/S, Tip up, 1150+TT
James extended cowl/plenum, induction, -8VS and Rudder. TSFlightline hoses. Oregon Aero leather seats.
D100-KMD150-660-TT ADI2- AS air/oil seperator. Vetterman exhaust with turndown tips.
Louisa, Virginia KLKU N94TB
Reply With Quote
  #8  
Old 02-04-2018, 11:22 AM
mfleming's Avatar
mfleming mfleming is online now
 
Join Date: Sep 2016
Location: Joseph, Oregon
Posts: 127
Default

Quote:
Originally Posted by Bob Martin View Post
"If the ship is moved without the fin being fastened in place, the aft fuselage can be damaged, and this extra fastener will keep the damage from happening."

Think ahead: Once the plane is completed. If you removed the VS. The bolts holding the tailspring weldmont to the rear bulkhead are also removed. At that point the weldmont is carrying the weight of the tail and is pushing up on the hole cutout in the rear bulkhead, a point load! and the rear bulkhead will tear/deform/fail, while sitting in your hangar!
Now, if you remember to reinstall the bolts back into the bulkhead through the weldmont, that will also keep the problem from occuring. But it is easy to forget or not see the problem coming...ask me how I know
What Mark is saying, is to preemptivly install a screw through the rear bulkhead into the weldmont to possibly save yourself a future problem.
Very clear now! That IS a gotcha.

That's an easy enough fix at this stage of construction.

Thanks for the tip.
__________________
Michael Fleming
Joseph, OR
sagriver at icloud dot com

RV-7 Slider #74572
Empennage (sans fiberglass)
Ailerons and flaps complete.
Wings done (sans fiberglass)
Started on QB fuselage
Donated 2017
Reply With Quote
  #9  
Old 02-04-2018, 02:14 PM
AAflyer's Avatar
AAflyer AAflyer is offline
 
Join Date: May 2009
Location: Belle Mead, New Jersey
Posts: 284
Default I made a shim...

Here's how I shimmed my bracket in my -8.

Using several different thicknesses and individual sheets, you might be able to fill the unsymmetrical void.
I had a void that varied from top to bottom, so I made one thick "baseplate", and then added successively smaller and thinner shims to form a "wedge".

http://websites.expercraft.com/dbw/i...y&log_id=73213

Hope this helps,
__________________
Bruce Windom
QB RV-8 N148BW
First Flight: Oct '16
AeroSport Power IO-360 180hp w/dual P-Mags
Catto 3-blade, with black carbon spinner.
10" Dynon SkyviewTouch. That's ALL.
2018 Dues Paid

Last edited by AAflyer : 02-04-2018 at 02:18 PM.
Reply With Quote
  #10  
Old 02-04-2018, 03:48 PM
mfleming's Avatar
mfleming mfleming is online now
 
Join Date: Sep 2016
Location: Joseph, Oregon
Posts: 127
Default

Quote:
Originally Posted by AAflyer View Post
Here's how I shimmed my bracket in my -8.

Using several different thicknesses and individual sheets, you might be able to fill the unsymmetrical void.
I had a void that varied from top to bottom, so I made one thick "baseplate", and then added successively smaller and thinner shims to form a "wedge".

http://websites.expercraft.com/dbw/i...y&log_id=73213

Hope this helps,
Nice!

I'm headed out to the shop to see if I can make the F-712 aft bulkheadit a bit flatter.

If not, then maybe I'll use your method.
__________________
Michael Fleming
Joseph, OR
sagriver at icloud dot com

RV-7 Slider #74572
Empennage (sans fiberglass)
Ailerons and flaps complete.
Wings done (sans fiberglass)
Started on QB fuselage
Donated 2017
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 12:51 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.