CARF-Models 2013 Series 3.1m Extra 330SC
06-10-2013, 12:49 PM
#151
RE: CARF-Models 2013 Series 3.1m Extra 330SC
I set up my tank using the instructions in the YouTube video posted on the PSP website.
http://www.youtube.com/embed/XNuFp_wbtNM
The process made it very easy to set up. I had a 100/140 watt soldering gun so the soldering went well. The guy was right on the 1/4" hole for the overflow barb. A normal drill bit really made an ugly hole. Next time I'll find one of those "barb" bits he showed.
The overall length of the brass section was 7" in the video and he had 1/8" between the Viton tube pickup and the dome at the bottom of the tank. My experience is that Viton expands when it's soaked in fuel so I soldered up my brass section with a total length of 6 7/8". I had1/4" from the end of the pickup to the dome on the bottom of the tank. I hope that's enough once the Viton expands.
In the video he mentions cutting off the brass tubing to achieve the 7" total length because every brass tube sent with the kits is a little different length. I ended cutting off over 2" from the tube they sent me. That was great news. The total weight for the completed tank was only 4.0 ounces!! 
06-10-2013, 12:51 PM
#152
RE: CARF-Models 2013 Series 3.1m Extra 330SC
The instruction manual showed pictures of the tank tray and the mounts. I was puzzled because I couldn't find the parts Isaw in the pictures.
The tank tray is built from a "3mm carbon-balsa composite material". It is super light but there is a LOT of carbon dust involved when working with the material. I would recommend a dust mask and gloves if you have any sensitivity to carbon or you just want to keep the dust out of your system.
I vacuumed the dust off all the parts and found some parts that looked like they were part of the tank tray and the mounts.
The other pile was parts that looked like they were part of the rudder servo tray (I didn't use) and some other mystery parts.
I didn't seem to have the standard plywood parts for the mounts. I looked through the manual and saw standard plywood being used for the "plywood cuboid" that goes inside the motor dome extension for a 2 cylinder engine. I looked inside the motor dome extension and found the standard plywood parts along with the bolts, washers, and blind nuts for the tank tray mounts.
06-10-2013, 12:52 PM
#153
RE: CARF-Models 2013 Series 3.1m Extra 330SC
I was still missing four small "carbon-balsa composite" pieces. Here are pictures from the instruction manual.
The manual says "The fuel tank base is supplied as 9 CNC milled parts...". Without those four parts I had 7 parts. If I were to use those four parts I would have 11 parts on my tank tray. Hmmm....
I looked at the tank tray design and didn't see why they were necessary. The rails around the tank already strengthen the tray in that direction. All I could see is maybe they retain the tie wrap that goes around the tank. I chose to go without them.
06-10-2013, 12:53 PM
#154
RE: CARF-Models 2013 Series 3.1m Extra 330SC
I put the two rails across the bottom on first. The tabs were 1/16" larger than the slots in the tray. I checked and the 1/16" need to be removed from one side of the slot to keep the ends of the rails flush with the edge of the tray. This carbon-balsa composite material is easy to trim with a sharp X-acto knife.
The rails are tacked into place with thin CA. Then sand the corner where the epoxy fillet will be placed and clean it with denatured alcohol.
I used 45 minute epoxy with milled glass. A key to note in this picture is that the fillet of glue does not go all the way to the end on the inside of the rail. The mounting tab will be in that spot so don't put any glue there.
06-10-2013, 12:55 PM
#155
RE: CARF-Models 2013 Series 3.1m Extra 330SC
The top of the tray gets the four rails that go around the fuel tank and they are installed in the same manner.
I made a few modifications to accept the 64 ounce Juicy Juice tank. The front rail needs to have some clearance cut for the spout on the bottle.
I used the Dremel drum sander to add a little clearance for the raised rings in the bottle.
I added some Viton to the clearance cut for the spout of the bottle. It was glued on with thick CA.
06-10-2013, 12:56 PM
#156
RE: CARF-Models 2013 Series 3.1m Extra 330SC
To keep the tank from rubbing on the tray I added a strip of Velcro to the back rail of the tray.
I addedtwo 1" squares of Velcro on the side rails. I added 1/4" foam underneath the tank. The foam was not put underneath the raised rings on the tank.
06-10-2013, 12:57 PM
#157
RE: CARF-Models 2013 Series 3.1m Extra 330SC
The completed tank tray is very functional and light.
The tank rests comfortably in the tray. It will be secured laterusing tie wraps.
The total weight of the tank and tray is only 7.7 ounces. Just 1.3 ounces more than the Dubro tank by itself. 
06-10-2013, 12:58 PM
#158
RE: CARF-Models 2013 Series 3.1m Extra 330SC
The mounts are assembled with one layer of standard plywood to hold the blind nuts and a layer of the carbon-balsa material.
The manual says to "install an M4 T-nut in each one in order to screw the mounts to the tank base". The blinds nuts and bolts in my kit were M3 and the blind nuts fit correctly in the plywood plates so I'm assuming the M4 was just a typo.
06-10-2013, 12:59 PM
#159
RE: CARF-Models 2013 Series 3.1m Extra 330SC
The manual says to "adapt the mounts to their position at the fuselage above the wing tube...". The mounts are going in a space where the fuselage is getting narrower as it heads towards the tail and is narrower at the bottom than the top. "Adapt" is a good way to describe it.
I started by setting one mount one each side of the wing tube.
The holes between the two mounts can be a maximum of 2.75" apart. They have to stay inside the rails on the bottom of the tank tray. The holes were 3.25" apart with the mounts sitting on both sides of the wing tube. It's time to decide how to "adapt".
I felt like the Juicy Juice tank has the CG of the fuel load further forward than the Dubro tank the tray was designed to hold.
Instead of moving both mounts 1/4" closer, I decided to slide the tray back 1/4" so the rear mount could be mounted with very little adapting.
06-10-2013, 01:01 PM
#160
RE: CARF-Models 2013 Series 3.1m Extra 330SC
The little bit of adapting for the rear mount is taking a little off the vertical support so it fits over the plywood ring that surrounds the wing tube phenolic.
The angle of the fuselage as it heads towards the tail is sanded into the mount.
After a little adapting it fits right were I want it.
06-10-2013, 01:02 PM
#161
RE: CARF-Models 2013 Series 3.1m Extra 330SC
Along with the tray and the tank, there is 3 to 4 pounds of gasoline supported by these mounts. I wanted to add a little extra support for the little tabs in the bracket that are inserted into the vertical pieces of the mount. I also wanted to spread the load across the fuselage side a little more. I added two strips of 1/8" bass wood above the bracket.
I added triangle stock under the bracket.
06-10-2013, 01:03 PM
#162
RE: CARF-Models 2013 Series 3.1m Extra 330SC
Before gluing them in the area is sanded and cleaned with denatured alcohol.
I glued the mounts in with Hysol. I put thick CA on the lower strip of bass wood so the mounts would tack to the fuselage side while the Hysol cured.
06-10-2013, 01:04 PM
#163
RE: CARF-Models 2013 Series 3.1m Extra 330SC
The front mounts needed to be 1/2" closer to the rear mounts. I removed the rear vertical piece from the front mounts and added two strips of 1/8" bass wood above and below the bracket. Those strips of bass wood were the correct length to rest against the former and have the screw holes in the mounts be no more than 2.75" apart.
The distance between the holes across the fuselage is 13". The brackets needed to be about 1/8" off the wall of the fuselage, so they were glued in the bass wood sandwich to create that spacing across the fuselage. The angle of the fuselage was sanded into the bass wood strips.
The clearance for the plywood ring around the wing tube phenolic is sanded into the bass wood supports.
These were also glued in with Hysol. Make sure the distance between the screw holes on the sides is no more than 2.75". The holes in the tank tray can easily be adjusted to match the mounts if it is less, but putting them further apart than that will not work.
Use the same trick of using thick CAon the inner bass wood rails so the mount tacks to the fuselage side while the Hysol cures.
Once the glue had cured I put the tray on the mounts. I hadn't considered the heights of all mounts so my tray rocked. I added a 3/32" plywood shim to the right rear bracket to get the tray to set solid on all four mounts.
06-10-2013, 01:06 PM
#164
RE: CARF-Models 2013 Series 3.1m Extra 330SC
This tray and mount has a heavy load that is being subjected to high Gs. The tray itself turned out very strong. It doesn't need the four little rails on the bottom at the ends of the tank. The mounts turned out to be VERY solid and secure.
I wasn't comfortable with one little M3 washer on top of the balsa composite material holding the tray down to the mount. I added some 3/32" plywood washers under the M3 washer to spread out the load.
The supplied bolts had about 3/32" of thread into the blind nut after adding the plywood washer. That would have probably been enough but I changed to a 16mm long bolt for the three corners and a 20mm long bolt for the corner that had the 3/32" plywood shim underneath the tray.
The tank has lots of room all around it.
It's a nice feature to have it removable.
06-10-2013, 06:54 PM
#166
RE: CARF-Models 2013 Series 3.1m Extra 330SC
ORIGINAL: underdw
I'm a fan of the 2-bottle system on quads (If I had one that ran). Hook one to each carb and you can gauge the relative fuel draw of each set of cylinders.
DU
I'm a fan of the 2-bottle system on quads (If I had one that ran). Hook one to each carb and you can gauge the relative fuel draw of each set of cylinders.
DU
Are you flying the August contest this year? I'm hoping we can get an Arizona crew to the contest again this year.
06-11-2013, 10:31 AM
#168
RE: CARF-Models 2013 Series 3.1m Extra 330SC
ORIGINAL: mu2driver
Nice build Dean!
I have been away from the hobby for some time now, but looking for something like this to fly...
Darcy
Nice build Dean!
I have been away from the hobby for some time now, but looking for something like this to fly...
Darcy
We need to have you flying again. Grab one of these. I know you could have the installs completed in a week!!
06-11-2013, 06:25 PM
#169
RE: CARF-Models 2013 Series 3.1m Extra 330SC
I tried to create an Extra 330SC instrument panel using existing instrument photos and MS Paint. MS Paint isn't photo editing software. I quickly gave up trying to create one. I took a picture of a complete instrument panel, printed it, and took it to Kinkos to have them make a copy that was 12.5" wide.
I cut a piece of 1/16" balsa slightly larger than the picture of the instrument panel.
I sprayed 3M Super 77 Multipurpose Adhesive (contact cement) on the balsa. I waited about 2 minutes, then applied the picture to the balsa.
I cut triangles out of a 1" wide strip of 1/16" balsa.
06-11-2013, 06:27 PM
#170
RE: CARF-Models 2013 Series 3.1m Extra 330SC
The instrument panel was trimmed to the correct shape for where I wanted to place it in the hatch. I added the 1/16" balsa triangles in the corners of the panel. I added a 1/4" wide strip of the 1/16" balsa standing on the side of the two center triangles to provide a little strength to the bottom center of the panel.
The instrument panel only weighs 0.3 ounces.
Test fit the panel in the hatch. It's key that the panel doesn't affect the way the hatch rests on the fuselage. I kept the panel totally clear of the edges of the hatch.
Once the panel was sitting where I wanted it, I put one drop of thick CA on the corner of each triangle.
06-11-2013, 06:28 PM
#171
RE: CARF-Models 2013 Series 3.1m Extra 330SC
With the panel tacked in place, test fit the hatch on the fuselage. Make sure the instrument panel hasn’t spread the hatch out or squeezed it together. The hatch should drop right onto the fuselage just like it did before the instrument panel was tacked into place.
The hatch still fit correctly. Itook the hatch off and applied Zap Goo to one side of each triangle.
And now I have a stand-WAY-off scale instrument panel. It meets the requirements. I've installed it in a fairly temporary fashion so I can replace it with something that looks better sometime in the future.
06-11-2013, 09:24 PM
#172
RE: CARF-Models 2013 Series 3.1m Extra 330SC
ORIGINAL: Dean Bird
The hobby has missed you!!!!
We need to have you flying again. Grab one of these. I know you could have the installs competed in a week!!
ORIGINAL: mu2driver
Nice build Dean!
I have been away from the hobby for some time now, but looking for something like this to fly...
Darcy
Nice build Dean!
I have been away from the hobby for some time now, but looking for something like this to fly...
Darcy
We need to have you flying again. Grab one of these. I know you could have the installs competed in a week!!
Yeah not anymore, my building skills have slowed down, I have been flying multi million dollar models, I can take off and land like no other...
06-15-2013, 01:00 PM
#173
RE: CARF-Models 2013 Series 3.1m Extra 330SC
I chose to install the ignition modules next. I decided to mount them on the front of the motor dome. I wanted to have them as close to the engineas possible to make sure the spark plug leads would reach the front cylinders.
I used an awl to mark around the ignition module.
I used the Dremelrouter bit to open slots for a Velcro strap.
I used thick CA to attach a piece of 1/4" foam under the module.
06-15-2013, 01:02 PM
#174
RE: CARF-Models 2013 Series 3.1m Extra 330SC
The Velcro straps are a very secure mount and the foam underneath the module protects it from vibration. There is some air flow outside the "air scoop" for the cylinder fins so I'm thinking they should like the cool air flow as well.
I attached the modules at a height where the upper lead will go to the cylinder on that side and the lead below the motor mount will go to the opposing cylinder on the other side of the cowl.
06-15-2013, 01:03 PM
#175
RE: CARF-Models 2013 Series 3.1m Extra 330SC
Before I added anything inside the motor dome I added a support for the firewall. I started with a paper template and transferred it to 1/8" plywood.
I created a second one that went further up the firewall and removed the useless material that provided no strength.