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.


Go Back   VAF Forums > Model Specific > RV-3
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 08-29-2010, 10:20 PM
Ironflight's Avatar
Ironflight Ironflight is offline
VAF Moderator / Line Boy
 
Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,872
Default RV-3 Aft Top Skin ? Our Approach and Lessons learned

The last major piece of raw material left in our hangar attic for the RV-3 project was the aft top fuselage skin ? the turtle deck. Having run out of excuses and most of the little tasks on the working list being complete, we figured this was a good weekend to give it a go for the initial fitting and drilling. I was shocked when I realized that we had it drilled to all but the F-306 and F-308 bulkheads after about ten people-hours of work! Here are a few of the things we took away from it ? YMMV of course.



1) As an experienced airplane builder now working on an RV-3 once said ?what airplane are these bulkheads supposed to be for anyway?? Laying a straight-edge from the rear bulkheads to the seat back showed that there was no straight line to be had here. Since we had put considerable time into the seat back bulkhead, and the F-309 (just ahead of the aft deck) looked pretty good, we decided to make those the baselines, and make the other two (306, 308) fit.

2) Making the 306 and 308 fit was simple ? we cut the flanges off entirely, and ground away web material until we had clearance between the bulkheads and the skin. The Louise made up some flexible new flanges that we?ll rivet in place (with a perfect fit!) once the skin is firmly attached to the longerons and fore and aft bulkheads. This makes for a smooth, straight skin.



3) Make sure to accurately locate the center line of the aft skin blank. We were just about an eight off, and it made for no extra edge distance along the longeron on one side at the back end. We could have fixed this by sliding the piece aft before we trimmed the front edge ? good lesson for next time.

4) If you have the tail mounted, take it off. Yeah, it looks really nice in the shop with the feathers on, but they are in the way.

5) A person can actually fit inside the aft fuselage of an RV-3, and do useful work back there! Louise was able to drill all of the longeron rivet holes back to about 6 inches from the F-309 bulkhead before running out of reach. I got those by reaching in through the holes in the aft deck and the -309 to finish the job. Please note ? Louise is an EXPERT cave explorer. It?s her job ? she is a trained professional!



6) Tension straps are a must, as they are for any skin fitting on the fuselage. Be very careful, however, not to start collapsing the side skins! It takes very little tension to do this ? go one ?click? on the cams at a time. You have been warned?.

7) Our drilling pattern was this. We predrilled the holes in the seat back bulkhead, and of course, the longerons. We then match-drilled the front center of the skin to the seat back. This was followed by one hole/cleco in the F-309 at the center to keep the skin straight. We then cinched up the tension straps, and drilled the skin to the longeron holes from the inside, alternating from left to right, one ?bay? at a time. We haven?t drilled the -306 or -309 flanges in place yet ? those should be fairly straightforward.



8) Take out the elevator pushrod and bulkhead. The baggage floor we left in place, then stuff moving blankets in to the ?floor? of each ?bay to bring the driller?s body up above the bottom of the bulkheads. Lots and lots of blankets. Much softer than cave rock?.



9) We cut out some thin plywood doublers for the 306 and 308 bulkheads, and attached them with C-clamps to make them flat. Once you cut off the flanges, they become noodles, and it will be very hard to get them straight and perpendicular to the fuselage for a nice line of rivets.

10) As always, we went slow, questioned everything we were doing, and stopped ourselves from doing something dumb on several occasions. Take nothing for granted!

More pictures at the Picassa Site: http://picasaweb.google.com/DrKarst/JUNIOR#
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
Reply With Quote
  #2  
Old 08-30-2010, 08:17 AM
C-GRVT C-GRVT is offline
 
Join Date: Feb 2006
Posts: 324
Default or (for next time)

to get the bulkhead heights to make a nice straight line, instead of cutting off the bulkhead flange and and rebuilding it, you could cut the bulkhead in two (so you have an upper and lower part), and then rivet it back together at the right height (higher or lower as necessary) with a doubler a la Sam Buchanan - see

http://home.hiwaay.net/~sbuc/journal/fuse3.html

The other important thing of course is to stiffen and support the bulkheads with plywood and braces so that they are not distorted/dislocated when the skin is strapped down for drilling.
Paul, looking good.

Bill Brooks
Ottawa, Canada
RV-6A finishing kit
Reply With Quote
  #3  
Old 08-30-2010, 08:31 AM
Louise Hose's Avatar
Louise Hose Louise Hose is offline
 
Join Date: Sep 2005
Location: Dayton, Nevada --- A34
Posts: 1,470
Default Or, maybe on a -6...

Quote:
Originally Posted by C-GRVT View Post
to get the bulkhead heights to make a nice straight line, instead of cutting off the bulkhead flange and and rebuilding it, you could cut the bulkhead in two (so you have an upper and lower part), and then rivet it back together at the right height (higher or lower as necessary) with a doubler a la Sam Buchanan
I don't see this method as working on the mis-fit of our -3 bulkheads. I think it would only have exasperated the problem, frankly. A different kit from a different time...

Quote:
Originally Posted by C-GRVT View Post
The other important thing of course is to stiffen and support the bulkheads with plywood and braces so that they are not distorted/dislocated when the skin is strapped down for drilling.
If you look at our photos on Picasa (or one of the posted ones carefully), we did use the plywood trick.
__________________
Louise Hose, Editor of The Homebuilder's Portal by KITPLANES
RV3B, NX13PL "Tsamsiyu" co-builder, TMXIO-320, test platform Legacy G3X/TruTrak avionics suite
RV-6 ?Mikey? (purchased flying) ? Garmin test platform (G3X Touch, GS28 autopilot servos, GTN650 GPS/Nav/Comm,
GNC255 Nav/Com, GA240 audio panel)
RV8, N188PD "Valkyrie" (by marriage)
Reply With Quote
  #4  
Old 08-30-2010, 08:53 AM
C-GRVT C-GRVT is offline
 
Join Date: Feb 2006
Posts: 324
Default

Louise,
you could well be right - but I think that the non-prepunched and non "cut to measure" 4 and the 6 kits provide a useful experience for tackling a 3. Certainly I imagine the shock when you open the crates and start reading the "plans" is not so great as it would be going from a 7 to a 3! "Just make it fit" has a somewhat different meaning.
Bill Brooks
Ottawa, Canada
RV-6A finishing
Reply With Quote
  #5  
Old 08-30-2010, 01:07 PM
Ironflight's Avatar
Ironflight Ironflight is offline
VAF Moderator / Line Boy
 
Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,872
Default

Quote:
Originally Posted by C-GRVT View Post
to get the bulkhead heights to make a nice straight line, instead of cutting off the bulkhead flange and and rebuilding it, you could cut the bulkhead in two (so you have an upper and lower part), and then rivet it back together at the right height (higher or lower as necessary) with a doubler a la Sam Buchanan - see
That would be another good thing for a builder to try Bill, I agree - but in this case, it wasn't just a height issue, it is the shape (and width) of the bulkheads. They actually didn't extend far enough "outboard" to bring the skin out ot the edge of the longerons - making them shorter would make that worse.

But as you say - this is the world of "make it fit", and whatever technique will do that for you is good!

Paul
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
Reply With Quote
  #6  
Old 08-30-2010, 03:01 PM
fredbauerjr's Avatar
fredbauerjr fredbauerjr is offline
 
Join Date: Feb 2006
Location: 36WI, Holmen, WI
Posts: 104
Default

For everyone dealing with the rear turtle deck let me say what I would do if we had it to do again.

I would not hesitate to make a fastback version of the -3!

You will have to deal with the bulkhead miss-alaignment anyway. By making a fastback version, (have you seen the -8 fastback?) you will #1 solve the air leaking from the rear canopy skirt (which is a lot) #2 solve the forming of the canopy skirt to bubble(trouble for all who have done this) It would be soooo much easier to fit the bubble down on to a "lip" on a fastback bulkhead and get a really good fit. Besides, I don't know of ANY 50 year old who can, (like an Owl) turn their head and look backwards. and lastly #3 get a better aircraft profile (like the -8)

Just my 2 cents worth.
__________________
Piper PA30b Twin Comanche, flying
Rotorway Exec 162F helicopter s/n 6985, built, flying
Vans RV4, s/n 2578, purchased, flown, sold
Vans RV3B, s/n 11366, built, flown, sold
turbine Mini500 helicopter, built, flown, destroyed thankfully
Swearingen SX300 co-builder, flown, sold
Vans RV4, s/n 37 built, flown, sold
Thorp T18, built, flown, sold
WAR 1/2 scale Corsair replica, built, flown, sold

Last edited by fredbauerjr : 09-20-2010 at 11:47 PM.
Reply With Quote
  #7  
Old 09-01-2010, 03:49 PM
KatieB's Avatar
KatieB KatieB is offline
 
Join Date: Jun 2010
Location: Belton, MO
Posts: 1,145
Talking

That's wonderful, Paul & Louise-- I'm printing this out and putting it in my instruction manual. Thanks!
__________________
Katie Bosman
EAA Homebuilt Aircraft Council
Rebuilt most of SNF tornado victim RV-3B Tony Boy II (had to sell him, but he's flying!)
VAF Dues Paid 2021!
Thoughts & opinions expressed here are my own, and not those of my employer.
Reply With Quote
  #8  
Old 09-02-2010, 09:36 PM
Louise Hose's Avatar
Louise Hose Louise Hose is offline
 
Join Date: Sep 2005
Location: Dayton, Nevada --- A34
Posts: 1,470
Default

Quote:
Originally Posted by fredbauerjr View Post
Besides, I don't know of ANY 50 year old who can, (like an Owl) turn their head and look backwards.
Interesting points and I may regret the resulting draft, but this 50+ year old can certainly see 360 degrees with my shoulders facing straight forward. I wanted to look all around.
__________________
Louise Hose, Editor of The Homebuilder's Portal by KITPLANES
RV3B, NX13PL "Tsamsiyu" co-builder, TMXIO-320, test platform Legacy G3X/TruTrak avionics suite
RV-6 ?Mikey? (purchased flying) ? Garmin test platform (G3X Touch, GS28 autopilot servos, GTN650 GPS/Nav/Comm,
GNC255 Nav/Com, GA240 audio panel)
RV8, N188PD "Valkyrie" (by marriage)
Reply With Quote
  #9  
Old 09-02-2010, 11:22 PM
az_gila's Avatar
az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
Smile This could have been...

Quote:
Originally Posted by Ironflight View Post
That would be another good thing for a builder to try Bill, I agree - but in this case, it wasn't just a height issue, it is the shape (and width) of the bulkheads. They actually didn't extend far enough "outboard" to bring the skin out ot the edge of the longerons - making them shorter would make that worse.

But as you say - this is the world of "make it fit", and whatever technique will do that for you is good!

Paul
...fixed at the fuselage frame jigging time. It was common on some early -4 and -6 fuselages to "adjust" the fore and aft location of the bulkheads from the plan measurements to ensure that the width was correct. Just make the bulkhead widths fit exactly between the longerons.

Then, if necessary, the height of the bulkheads could be adjusted by cutting and splicing as mentioned above to ensure a straight line from cockpit back to the tail of the turtledeck.

Too late for this fix in your case....
__________________
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
Reply With Quote
  #10  
Old 09-03-2010, 07:09 AM
Ironflight's Avatar
Ironflight Ironflight is offline
VAF Moderator / Line Boy
 
Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,872
Default

Quote:
Originally Posted by az_gila View Post
...fixed at the fuselage frame jigging time. It was common on some early -4 and -6 fuselages to "adjust" the fore and aft location of the bulkheads from the plan measurements to ensure that the width was correct. Just make the bulkhead widths fit exactly between the longerons.

Then, if necessary, the height of the bulkheads could be adjusted by cutting and splicing as mentioned above to ensure a straight line from cockpit back to the tail of the turtledeck.

Too late for this fix in your case....
Actually, in this case, it's just not true Gil. The bulkheads simply aren't shaped exactly right, no matter where or how you place them on the RV-3. There are significant differences to the width of the bulkhead just above and just below the longeron, so you have to use very thick, tapered shims, or come up with some other way of fixing the gaps. The build instructions tell you this, and recommend cutting off the flanges and making new ones to ensure a good fit.

The RV-3 is not at all like the follow-on kits - you really do have to be comfortable with significant modifications to put this one together!

Paul
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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 04:26 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.