RE: GP Extra 300S 60 Build
 

About to cut the cowl for an inverted Saito 125a. Before doing so I was wondering if a flexpipe would enable the exhaust to stay inside the cowl then exit closer to the firewall on the underside. What have you all done?

RE: GP Extra 300S 60 Build
 

Andrewmc,
My saito 120 has a cuved pipe on it. I adjusted it and the muffler to make it hug the bottom of the fuse. It is hardly noticeable from the air. You have to cut the cowl for an air exit anyway.
Good luck.
Alan

RE: GP Extra 300S 60 Build
 

Well we got almost 3ft of snow four days ago so I wont be flying anytime soon. I was snowed in until today :D. I do have another switch on order and I'm really itching to get thing plane in the air.

RE: GP Extra 300S 60 Build
 

Alan,

I saw where you mentioned landing gear problems with your Extra. Is it just sheet metal screws pulling from the plywood or something else? What would you do different.

Time is getting closer for me to start my Extra.

Thanks,
Rick

RE: GP Extra 300S 60 Build
 

Still busy with the covering prep and general sanding - not getting much time to work on it so progress a bit slow.

I decided to reinforce the belly pan attachment to the wings with an epoxy (and micro balloons) fillet. I used 30 min epoxy and added microballoons to the consistency of about peanut butter, the outside temperature (Cape Town summer) was 42 celcius - really hot, the epoxy plasticised in less than 5 min.

Some photos, still need to finish sand the belly pan generally but wanted to post progress.

Another question - has anyone added the optional fuselage side rails (parts 34 & 35)?

RE: GP Extra 300S 60 Build
 

Hey Rick, Sorry I have not answered your question yet. I just checked in, and saw it. I have come in a little hard and pulled the screws out. I have just put them back in. I had reinforced the ply strips with some bigger ply. So far it has worked. If the screws get where they dont stay in I will go with blind nuts and nylon screws.

Andrew, Yes I did add the side rails. I think it looks very good and it was really easy to do.
Alan

RE: GP Extra 300S 60 Build
 

Instead of using the wood screws straight into the plywood I mounted the landing gear on mine I went with blind nuts and 1/4-20 nylon bolts. Both methods have their good and bad points. I've had a few deadsticks on take off and had to ditch in the tall grass at the end of our runway. The nylon bolts worked perfect and snapped right off. Unfortunately, when the gear comes off it usually wrecks the first belly pan former. I've also had the wheels go through the covering on the bottom of the wing. On the other hand, that might be a lot less damage than would have happened if they were screwed in with wood screws.

RE: GP Extra 300S 60 Build
 

Need some help.

I have bought a Dubro 4/40 pull pull kit for the rudder. Installation has gone well up to the point where I need to attach the wire to the eyelet.

The wire is nylon coated and is supposed to go through the tube then the eyelet throughthe tube again and then loop back around through the tube, then crimp the tube and cover with heat shrink.

I think the metal tubes that I have are one size too small, I cannot even get the second pass through the tube let alone the third without stipping off the nylon sheath - which I am sure is not the way it is supposed to be done.

Is there a technique to thread the tube with the wire? or have I misinterpretted the instructions? (Been trying for over an hour to do one, let alone 4)

RE: GP Extra 300S 60 Build
 

Sounds like what I did. You may need some bigger tubing. I didn't have any trouble with mine.

RE: GP Extra 300S 60 Build
 

Hi Alan - did you strip the nylon to get it though?. If I strip enough to get through the tube the second time, I can use pliers to pull the unstriped wire through, but not a third time.

RE: GP Extra 300S 60 Build
 

Andrew,

My suggestion would be to very carefully shape the tube to an oval instead of round. Then you should be able to get it to go. Assuming that you want the cable in the third time.

I have always been successful with running the cable through the tube around the eyelet through the tube again then crimp. Cut with about 1/4" hanging out and cover with heat shrink. Be careful when shrinking the heat shrink. You can melt the covering on the wire. Not that - that will be a big deal. just a place for corrosion to start some day long from now.

Other alternatives can be properly sized brass tubing. Heck even the aluminum tubing will work. Reference here, being the K&S variety. In reality part of a electronic "crimp" wire connector will do the trick as long as the size is right.

Good Luck....

RE: GP Extra 300S 60 Build
 

I did not have any trouble getting the wire thgough three times. If you are having that much trouble something is not right. If you bought it at the Local Hobby shop I would take it back. On mine I could have run the wires through 4 or 5 times.
Alan

RE: GP Extra 300S 60 Build
 

I read a post on another thread indicating that sometimes the wrong size tube is included, i.e for .20 wire instead of .03. I think I have one of those! - Unusual for Dubro products I have never had issues with them before.

I can get the wire through twice so I will continue with what I have.

Thanks for the help Alan - How is your plane flying? Or is the weather keeping you on the ground? It is summer here with clear blue skies and temperatures up around 36 celcius but strong winds, early morning flying only I have been getting to the field at around 05h45 manage to get 2 hours or so before the wind gets up over 25km/h.

RE: GP Extra 300S 60 Build
 

Finally got the plane together in the bones to check CG and lateral balance.

Pull-pull is installed using electrical crimp fittings (I think the hardware in my pull pull kit was for the 2/56 and not the 4/40, the supplied heat shrink wouldn't fit either), currently set-up with a single elevator servo, but depending on the CG requirements I may replace with rear mounted seervos for each elevator half.

I will check the CG this evening and also recheck the wing incidence and decalage again before covering.

AUW at this stage (everything except canopy and covering and balance weight) 3.3kg (7lb 3oz) not to bad.

Already starting to think about the next build :).

RE: GP Extra 300S 60 Build
 

It is hard to tell from the Photo #3, but did you mount the servo for the pull-pull rudder at the stock location or did you "lower" it to a more middle of the fuse location (height wise, not length wise).

I ask because where the stock location is seems very high in the fuse relative to the angle the wires will run toward the rudder exits.

I just starting laying that run out last night and started to wonder...

RE: GP Extra 300S 60 Build
 

Andrew

Your Extra is coming along nice….[8D]

With the color you have on the rudder and elevators, I am anxious to see how the color scheme turns out. At 7 1/2ish lbs it will be a nice fling machine.

By the way, what is the next build looking like (which plane[sm=50_50.gif])????

RE: GP Extra 300S 60 Build
 

Chemie, I installed the pull pull cables in as straight a line as possible and installed servo rails to suit, this is about 1" lower than the stock location (lower being closer to the wing top)

Some other photo's which may help clarify.

Hi Rick, quite pleased (if somewhat surprised) about the low weight. Some people have indicated weights in excess of 8lb with the larger 4 strokes.

The next build is a 1/4 scale Tiger Moth from plans (short kit from Traplet, Duncan Hutson Design). 2.2m wing span and a 1.8m fuselage - 35cc glow engine.

Planning this one for competition so could be a long build, looking at the calendar this one has taken 10 month so far LOL.

I will try and check the CG a bit later and post any additional weight requirement.

RE: GP Extra 300S 60 Build
 

Oops. Needed 240g (Almost 8oz) to balance - roughly. Going to move the servos and battery to the back and try again. Need another servo though. Off to the LHS tomorrow.

RE: GP Extra 300S 60 Build
 

Andrew,
You might want a few flights without the wheel pants. I have pulled LG our before with wheel pants and poped a hole in my covering. So far with my extra Ihave pulled them out twice and no had a hole. I left off my wheel pants. I did not like the way they go on the LG.

Other than my suggestion your plane looks great. I too am interested in what the final design will look like.
Alan

RE: GP Extra 300S 60 Build
 

I was not sure if it would be better to "lower" the servo versus shimming the servo angle so the wires were parallel to the servo arms.

I am glad you were nose heavy as my main worry is being tail heavy with the rear mounted elevator servos.

RE: GP Extra 300S 60 Build
 

If I position the battery (6v 1500mAh) behind the wing - need to wiggle under the rudder cables and push rods, I can balance the plane without adding weight, or moving the elevator servo.

I have bought another servo though so now the question to move the servo's back ve the servos back.

Keeping the single servo inside the fuselage is more aesthetic but two elevator servos would be easier to set up. Would I use a Y splitter or does each servo require a separate channel?

If the elevators are on separate channels can the ailerons be on a Y splitter?

RE: GP Extra 300S 60 Build
 

Andrew,
I would jut run one servo for the elevator. Mine balances pretty close to what you are saying. I have a Saito 120 on mine. The battery is just in front of the former at the back of the wing. On a flat spin she will flatten right out. The single servo is a little harder to match up, but if you have gotten this far it should not be a problem.
Alan

RE: GP Extra 300S 60 Build
 

Andrew,
I for got to mention that I have Futaba 3010 servos on mine all the way around. 90oz of torque with these.
Alan

RE: GP Extra 300S 60 Build
 

Thanks Alan

I used standard servos for all except the rudder, which has a high torque servo. Can't recall the torque in oz, all metricated over here but 9.5kg.cm.

RE: GP Extra 300S 60 Build
 

Andrew,

Which radio are you using. Example the Futaba 7C - you can set up dual servos for elevator and ailerons using separate channels for each. An extremely easy set up.

If you use a Y on elevators, a servo reverser is also required unless you do some funny business with the servo location.

Ailerons can be hooked up with Y harness and no reverser. But you lose some programming capabilities if you have a computer radio.

As to two servos for elevators, personal preference and dependant on servo and flying style. My-self I would use two servos (one each elevator) especially when using standard servos on this plane with that much power. Again that is just a preference.

Good luck……………