2.6 Comp ARF Extra 300SX w/ DA-85

[bmoney69]

i get soo much usefull information on this site that i thought i'd take a moment and post some pics and information of my recient project. there doesn't seem to be a lot of comp arf extra's with a side mounted DA-85, so here is my version. this isn't a build thread, but more of a post build thread. i kept it as simple and light as feasable. (1) servo per surfaceEnjoy!

DA-85 side mount w/ K&S custom X-header & MTW TD110k canister
PT 26x10 CF prop and CARF CF spinner
JR DSM 2.4 922 power safe Reciever w/ soft switch
(3) 8711's (rudder, ailerons)
(2) 8611's (elevator)
(1) S3003 futaba (throttle)
TBM CF wing and tail tubes
5" TBM foam wheels
PT CF tailwheel
1.5" SWB arms with a full 4" for rudder
DA fuel dot
Dubro 32 oz tank
Duralite 2150 A123 (2) reciever
NOBS 1100 A123 (1) ignition

AUW dry is an honest 23.5 lbs

[bmoney69]

Engine install: had to go with a cross over header because a standard drop header won't give you the length needed (10.5-11.5") the Canister can only go back soo far before you run into the wing tube. also seen here is the manual choke. the engine mount is laminated 1/8" and 1/16" ply from PAU.

[gene6029]

bmoney69, does the 85 poke thru the cowl any on the 2.6? I have a 2.3 w/the 85 mounted inverted @ 20lbs 4oz & was thinking of getting the 2.6 & putting a 50 back in the 2.3. I really like the way the 2.3 flies, but i never really get to open up the throttle w the 85 in it. I flew it all this past summer & with no issues & keep looking at its bigger brother....Gene

[bmoney69]

Hey Gene.....you beat me to it....i was just about to show that! the answer is yes, the cap sticks out a bit. it doesn't bother me and i really didn't want to cut the whole bottom of the cowl out, so that's the reason for the side mount. also shown is the baffle made from 1/8" balsa, painted to match cowl.

[bmoney69]

some pics of the insides. i added a sacrificial 1/16" plywood plate under the canister and on top of the CF landing gear to protect it from the heat. the holes in the fuse are to allow the heat from the canister to escape. it's roughly 2x the area of the intake. the tabs at the leading side of the exhaust holes are to create suction to help "pull" the heat from the fuse.

[bmoney69]

the black ring around the exhaust holes is CF take laminated to the fuse to reinforce. i was careful not to cut thru the seam down the center of the fuse. it's reinforced with fiber cloth and cutting it could compromise the structural integrity of the fuse. hence the reason for two holes instead of one.

[bmoney69]

all the work in the fuse was done with aeropoxy. yes it's expensive and yes you can probably get away with epoxy and milled fiberglass, but for me, it's worth it. it's thixotropic and you never have to wonder if it's going to fail.

[bmoney69]

shown here is an easy, clean way to mill holes in composite material. i used this method for the carb needle access thru the cowl and all of the servo wire penitrations. choose a fender washer that has the apx size ID as the hole you want to make. tape it in place, and use a milling bit in your dremel tool to route out the material.

[gene6029]

I'd like to see a picture of it once its assembled. Looks like it was really close to fittin in there....Gene

[bmoney69]

i used (3) remote recievers attached to the fuse with industrial strength velcro. all the wires are secured to the fuse with velcro and the ignition, fuel tank, and batts are all secured with velcro straps. they absorb vibration better the zip ties.

i milled out the slots in the elevator and rudder to achieve 45 deg throws. i also extended all the slots where the servo arms protrude to gain more travel.

pics of the baffle and the manual choke lever (didn't want to waste weight on a servo and it's very easy to access)

[bmoney69]

i didn't take a pic of it, but the rudder is held in place with a steel rod running thru phenolic guides in the fin. the instructions tell you to put a 90 deg bend in one end and use a collar tie on the other. i don't particularly like the way that would look so i cut the wire about 1" short and use 1/2" SS button head screws top and bot to secure the rod. much cleaner and safer.

tail whell install. nothing special, drilled two holes in the phenolic rudder horn to attach springs to the tail whell for better ground control.

nothing special about the canopy install. did it pretty much the way the manual described except i didn't use CA on the outside. didn't want to risk seeing it. i used duct tape to make tabs as described in the manual, but then i ran duct tape around the entire seam of the canopy and frame. when satisfied with the fit. i took the whole assembly off the fuse turned it over and put a few drops of ZAP + on the inside to secure it in place then ran a bead of aeropoxy around the entire perimeter.

[bmoney69]

this is my second comp arf and once you build one, you've pretty much figured out the tricks. it's pretty st8 forward. please respond to this thread if you have any questions, i'll be checking it.

hope you enjoy!

[bmoney69]

Gene, yes, it's very close to fitting, but the key word is "close" to ensure that the cap doesn't rub the fiberglass cowl you have to mill a small opening. if you clocked the engine at say 135 deg (referencing mine at 90 deg) you may get the plug far enough away. not sure what that does to the exhaust or the engine mounting holes. i think you'll be off the fire wall and have to fabricate something to pick up the bolt.

[gene6029]

Thanks for the pics, looking good. Gene

[dbcaster]

I had the DR Hobbies 2.6M Extra with an 85 at 23 lbs. It was one of the best setups I have had. If you have not flown the plane yet you will love it. I lost mine due to a poor battery mounting on my part. I sure do miss it