GP Extra 300S resurrection
 

After just getting the kinks out of my kit built Extra 300S and considering the engine fully run in, it decided to take on a mind of it's own and nosed in at full throttle, albeit from low level.

It was the firs t flight of the day and I had the air to myself so was taking the opportunity to practise rudder control by doing cross wind runs up and down the length of the runway. After completing my fith or sixth runway pass I started to pull up to enter the downwind leg for landing approach. I glanced down at the timer on the radio and on resighting the plane it was belly up and going down, i had a split second to try and pull out before seeing the puff of dust followed a second later by the dreaded crunch.

I still do not know what happened, I am tending towards banking the plane for the downwind leg with the aileron and then not releasing when I glanced at the timer causing the plane to roll. If not that then the only other thing is an electronics glitch - not impossible but less likely.

After the "long walk" to collect the pieces, a fellow club member asked if I would rebuild the plane I almost laughed looking at the extent of the damage. Debris was spread over several metres, the fuel tank and battery had been thrown loose and were some distance away from the fuz wreakage. The wing bolts had held and the wing had snapped 1 bay out from the fuselage (just after the wing joiner). There was nothing left of the fuselage forward of the cockpit, and yet the tail looked pristine.

Placed the bits in the garage for a few days to contemplate things. As the fuselage plans are not full size I could not make new fuselage side panels from the plans but all the other formers could be pieced together enough to trace and I decided the wing wasn't that bad after all. So a quick look at the Great Planes website revealed that they sell the diecut fuselage sides for a couple of dollars so I opted to get the complete fuselage die cut parts for around $15 or so (shipping to South Africa was another $20, ouch).

The shipping time allowed me to effect the wing repair while the parts were being shipped, so put my Tiger Moth Build on hold for a while to resurrect the extra - it just flew too well to trash.

RE: GP Extra 300S resurrection
 

Man that's too bad. Iknow how you feel... we have that same plane, in about that same shape sitting in the shed. Lost radio responce, and went in.

Looks like you know what your doing anyways, it is worth saving that one :)

Best of luck.

RE: GP Extra 300S resurrection
 

Shimano - Thanks for the encouragement - feel free to rebuild yours in this thread to if you like....

Stripped the covering from the wings to assess the damage. The main spar had snapped between bays 3 & 4 literally just after the ply wing joiner. After deliberating how best to join the broken parts I decided to make up a spruce "fill piece that would taper from the root, 1 bay past the break to fit inbetween the upper an lower spars. I did not feel that splicing the spars would be quite strong enough. Also by using the filler piece the correct alignment of the wing was guaranteed.

As the wing which broke was the one which had the balancing weights added to it I am not overly concerned about the additional weight of the spruce addition.

First 2 photos of the "as crashed" wing with the covering stripped.
Photo 3 of the joined wing with the spruce filler glued in position.

RE: GP Extra 300S resurrection
 

Using the die cut sheets from the kit as stencils I traced and cut out new ribs for the R2, R3 and R4 and ten used the remaining sheeting as a guide sandwiched them to the broken ribs (Photo 1 & 2).

Then repaired the damaged trailing edge (Photo 3).

Replaced sheeting LHS (Photo 4) and then RHS for which I don't seem to have taken a photo - sorry:eek:

RE: GP Extra 300S resurrection
 

When the parts for the fuselage arrived from Great Planes (10 days - half way across the world. Thank you Mary Ann at Hobby Services, Great Planes), I got cracking on the basic build. Laid out the fuz floor then added formers 6 and 7. Then using a spray bottle of water wetted the fuz sides (in turn) and going a little bit at at time using thin CA and kicker joined the fuselage sides to formers 6 and 7.

With that difficult part done then proceeded to add the balance of the formers and the fuselage floor. After I finished that I was not overly impressed with the fit of the tab locking parts around former 8, 9 and 10. And funnt enough when I went back and re read my original build thread the same thing had occured. i could have kicked myself for not re-rading the original thread first and repeating the same "mistake" again. For those about to embark on this build take a bit of time arund the last three formers and sand a bit to get a good fit before glueing - this makes a difference when fitting the wing saddle components.

I salvaged the undercarriage supports from the crash and remade a stiffener to fit in between them to strengthen the structure. This time (Having read my original thread) I installed these parts before adding the engine box components - much easier :). Photo 1 and 2

Also using the experience from the first build I cut back former 6 fuel tank support to accomodate the inverted saito 125. Final position 6mm off fuselage bottom (at the firewall end) and then used scrap ply to make a support at the other end of the tank floor. again easy 2nd time around.

RE: GP Extra 300S resurrection
 

Re seated the wing in the new saddle without incident. And then set about salvaging the tailplane. photo 1.

I cut the lite ply as close as possible to the HS and then laboriously sanded all remnants away until all I had was a clean Fin joined to the HS complete with tailwheel.

I fitted the wing to the plane and shimmed one side of the fuselage with a grocery store receipt ;) to make both wing tips level - it does not take much at the fuz to have a big effect at the wing tips, even so A grocery receipt? I did have to fold it though, once:eek:.

I set up the wing incidence using a robart meter (0.5 deg neg relative to wing). I needed to sand the HS saddle very slightly to level off the stab - double checked everything and glued and clamped.

Fin is beautifully perpendicular to the stab and the stab alignment with the wings is within 1mm either side - can't really do much better than that. All in all quite chuffed with how the old parts fitted with the new fuz.

Now to make the turtle deck and fit the hardware. This is where I currently am with the build and no I didn't do all of this in one day. :D

RE: GP Extra 300S resurrection
 

Nice work!Iwould bet she flies better this time around, too.:)

RE: GP Extra 300S resurrection
 

Andrew,

Obviously, I am a little slow at catching up with you on these post. Man, I hate to read what happened to your Extra. None the less, it looks like you are well on the way to putting it back together. Good Luck......

RE: GP Extra 300S resurrection
 

i actualy sat and watched the build thread you had of it. I still have to find some time to do some more on mine and get it finished. hope to see it in the air again soon.

Ps what did it fly like? anything you would change if you was to build another?

RE: GP Extra 300S resurrection
 

I had the original one set up with dual elevator servos rear mounted - having done it that way I am not sure how much value it added so I am doing this one as per design with a single centre mounted servo, for comparison.

I installed a pull pull rudder which I really liked and will refit. Other than that the plane was pretty much stock. A mod here or there to suit the specifics of the engine choice and that was about it. Oh and I added 1" to the bottom of the rudder, again not sure how much value this adds but the rudder was undamaged and I have refitted it. Don't think I would bother with that if I had to do it over.

The flight characteristics were great. Did not get pushed around in the wind, stall turnswere easy and impressive, roll rate good (standard aileron) if I recall about 4 rolls in 3 seconds. It does a reasonable knife edge albeit with a significant belly tuck - but 5% rudder to elevator mix improved that. i did not push the 3D envelope but IMAC type manoevers were all within the planes capabilities restricted only by the pilot.

The stock landing gear gets bent out of shape fairly easily. I noticed one wing dipping a little on take-off and found the landing gear to be bent but I do not recall any rough landings!

Generally I think if you build this plan stock it will be fantastic, keep the weight down and it will be superb.

Hi Rick - glad you are still looking in. Have you got around to getting yours on the board yet?

RE: GP Extra 300S resurrection
 

Hey Andrew,

Admittedly it’s still in the box exactly as it was packed at Great Planes.[:o] I’ll spare you all the details[&:]......

I am looking forward to seeing how your rebuild turns out.
Also, when you originally built yours, I remember you mentioning the addition of a longeron or two for more scale appearance. Was that the case and will you do that again?

RE: GP Extra 300S resurrection
 

From building the plane first time around I recall that the turledeck sheeting "sanded through" on more than one occasion. Withthe rebuild I have sheeted both the front and rear turtledecks with 3/32 sheeting and not the original 1/16. I think that works much better.

Now to install the servos and pushrods.

I have opted to go with the original design for the elevators with a single fuselage mounted servo with a pushrod for each elevator half. This means I need a trip to the LHS to get some pushrod material.....

I have reinstated the pull-pull from the original but have left the servo rails loose so that I can adjust the CG a little.

RE: GP Extra 300S resurrection
 

Doesn't time fly when you're helping other people to have fun! Two years since the last post and almost no progress with the extra. But dusted it off today and took out the sanding block and got ready for covering. A touch of filler and microballoons any starts to look (feel) great. Does anyone else stroke their planes to determine if they are ready for covering? :eek:

I made a cradle for the battery under the cockpit and a support for the receiver. I will need to neaten up the wires but you get the idea...

It feels great to be back at the building board after so long - but my wife is expecting our third child any day now so making hay while the sun shines.

Charging up the batteries of my 4 star as tomorrow looks set to be a perfect flying day in Cape Town. 1st time flying since October what with work, weather and breeding LOL.

And another year goes by,....don't get to go into the :work room" very often now but have managed the past couple of days to steal some time while the kids are snoozing and the wife is looking the other way!

I have not been completely idle, the wing is now fully covered complete with trims and the fuselage is now finished and final filling and sanding of hanger rash all done.

Fuel proofed the tank bay this evening - may be the last glow fuel user at the club as it seems most folks have gone over to petrol - I have quite an investment in glow engines so this one stays with the saito 125 (for now).

Hope to start covering the fuselage tomorrow when the fuel proofing dries - ah the smell of polyurethane varnish wafting round the house - been a while!

Some pics of the covered wing and the engine bay all fuel proofed.http://www.rcuniverse.com/forum/atta...mentid=1989720http://www.rcuniverse.com/forum/atta...mentid=1989721http://www.rcuniverse.com/forum/atta...mentid=1989722