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Using a Rotisserie

G

gpiney

Well Known Member
I have access to a rotisserie already set up for an RV8. Here is my question. The builder who gave me the rotisserie first drilled and mounted his motor mount, then fabricated the rotisserie mount based on the holes he drilled in the firewall weldments. I do not have the motor mount and need to know how to drill the holes in the firewall. Are the factory holes in the stainless firewall accurate? What would be the minimum size hole to use, knowing I will have to enlarge them when I get the motor mount? Are 1/4" bolts big enough to hold the structure? Are the motor mounts from the factory 'real close' to the firewall holes (less than 1/16' off)? I suspect the jig they use to build the mounts is 'exact' to the plans, but I have heard that no 2 mounts are exactly alike.

Your comments, suggestions and pictures appreciated.
 
Rotisserie

I used 3/16" bolts and the pre-punched holes in the firewall. In general, these holes were a good match to the engine mount-but not perfect. The bolts were plenty strong enough to support the airframe...but I wouldn't climb into it on the rotisserie to be on the safe side.

I wouldn't recommend a 1/4" hole without having the engine mount on hand to match drill since this won't leave any margin for adjustment to the engine mount.

Good luck,
Mike
 
Fuse is light I saw somewhere on the web a builder used AN3 bolts successfully. One bolt on the mount was off center a bit but he was able to drill it right because it was AN3. With bigger bolt he would be out of luck. I see if I could find the ref.
 
Transporter said:
I used 3/16" bolts and the pre-punched holes in the firewall. In general, these holes were a good match to the engine mount-but not perfect. The bolts were plenty strong enough to support the airframe...but I wouldn't climb into it on the rotisserie to be on the safe side.

I wouldn't recommend a 1/4" hole without having the engine mount on hand to match drill since this won't leave any margin for adjustment to the engine mount.

Good luck,
Mike
Click to expand...

Ditto that, it's what I did on my 9A.
 
gpiney said:
...... What would be the minimum size hole to use, knowing I will have to enlarge them when I get the motor mount?.....Your comments, suggestions and pictures appreciated.
Click to expand...
Greg,

I drilled the holes for and used 3/16" bolts at the four corners of the firewall. As long as you do not attempt to climb inside the cockpit, AN3 bolts are more than adequate to do the job. Here's a suggestion. As you can see, I wanted to be able to rotate the fuselage with the gear legs attached, so when I built up the rotisserie, I extended it's height accordingly. The convenience cannot be overstated. Using the rotiserrie, internal access is much easier than the alternative and many, many tasks are easily accomplished while comfortably seated on a stool. The aft fuselage is supported by a padded sawhorse. I never needed any help to adjust the rotation, only making certain that when I did so, I did not accidentally "walk" the fuselage off the sawhorse!

2njm2yx.jpg
 
Blue plastic

Greg,

(slightly off topic)

The picture is not that clear but it looks like you didn't remove the blue plastic from under the rivets. I doubt that is true. It doesn't have the usual "soldering iron" plastic deletion stips that fuses usually have.

Did you do it another way?
 
GusBiz said:
Greg,

(slightly off topic)

The picture is not that clear but it looks like you didn't remove the blue plastic from under the rivets. I doubt that is true. It doesn't have the usual "soldering iron" plastic deletion stips that fuses usually have.

Did you do it another way?
Click to expand...

Those are Rick's pictures. I've seen closeup pics of what he did with the blue plastic.
 
When it comes to RV's, it is increasingly difficult to do something no one else has done. I also knew that most people just can't wait to peel the vinyl off the parts and will cite you any number of reasons to quickly remove it.

I happen to like the look of blue vinyl. Personally, I find its color preferable to cookie cutter boring, bare aluminum. Also, I wanted my airplane to be the first ever RV to fly with its protective vinyl still intact. During the building process, I found that removing a small chunk of vinyl from around each and every rivet was a modest, easily attainable goal driven in part by simply wanting to be first at something. There it is.

http://www.vansairforce.com/community/showpost.php?p=550652&postcount=25

http://www.vansairforce.com/community/showpost.php?p=511596&postcount=12
 
I am a lesser man

Rick,

I appreciate your professionalism and you are an example as to how I should build an aircraft. I say that in total truth. However, that is just SOOO MUCH more work than I would be willing to do.

I will be painting. I am stripping that blue stuff like its no tomorrow.
 
GusBiz said:
......that is just SOOO MUCH more work than I would be willing to do.....
Click to expand...
I completely understand your point of view Gus and you can be certain most other builders
feel the exact same way. Unlike you and others, I didn't view it as "work." Ironic isn't it that
my effort seems entirely consistent with the tagline you choose to include with your posts? :)
 
Climb away!

Transporter said:
I used 3/16" bolts and the pre-punched holes in the firewall. In general, these holes were a good match to the engine mount-but not perfect. The bolts were plenty strong enough to support the airframe...but I wouldn't climb into it on the rotisserie to be on the safe side.
Click to expand...

I too used the pre-punched holes and 3/16" bolts (Grade 8), and I climb into mine all the time. If you run the numbers, you'll find that the weight necessary to shear the bolts or to fail them in tension is in the thousands of pounds.
 
Last edited:
Thanks everyone for your suggestions. When the time comes that I need to get into the fuse, I will add a padded sawhorse under the center section for additional support. I will either use AN3 or grade 8 3/16" bolts. I am going to start the holes by drilling 1/8" holes then expand them with a #12 bit.

Anyone have suggestions on how to match-drill the rotisserie mount to the holes?
 
When to mount to rotisserie?

On a RV8 slow build, does the fuselage need to be riveted prior to mounting to the rotisserie or just clecoed?
 
Rotisserie

Here is how I did it...I put it in clecoed. It's easier to rivet in the setup.

http://i51.tinypic.com/k0kenr.jpg
http://i51.tinypic.com/8y8d94.jpg
http://i54.tinypic.com/2ywzfx0.jpg

Since just sticking a pipe in the tailwheel stinger hole is off center I tried to adjust and this came pretty close.

The assembly uses 1/2" pipe, a 6'', 12" and 4 1/2" section with 2-90 degree elbows and a cap. I drilled through all the elbows to keep the joints from slipping as the fuselage is rotated. Worked great...also drilled and can be seen to bolt into tailwheel stinger socket.

On the top of a saw horse I installed and eye bolt for my pivot point.

Of course there is also an engine stand on the front but that goes without saying...
 
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