Progress Update:

Right wing bottom completed. - Next step joining the wing halves. Mmmmm

I joined the wing halves before I sheeted the wing[X(]

Only the bottom of the wing is sheeted at the moment. The top gets sheeted after joining.

right on. I've glassed and painted mine white so far. Have you decided on a color scheme for yours yet?

Not decided on a colourscheme yet, I have several part rolls of white, blue, yellow, orange and red ultracoat, so i am sure i can do something with that

Have not thought about the graphic though, maybe red based upper with white underneath with blue wing stripes.......

I'm getting my wing joined today.

It seems that the GP wing and the Goldberg wing joining process came from the same origins. The Goldberg doesn't have a rear spar. Just the TE. It appears the GP kit has a rear spar. Is this correct? It is nice to compare the two kits.


Somedays I feel like I am racing to build slower than everyone. I love building, but can only accomplish anything over the weekends.

How's yours coming Andrew?

Brian

Got a problem with interpretation of the plans.

On the trailing edge of the wing frames it instructs to trim the sheeting so that it is 1/2" longer than the ribs, which I have done.

The instructions then show a diagram of how the TE should be sanded (photo 2)

But to sand it this way there is much less than 1/2" of sheeting. If I sand the sheeting back like this won't it affect how the plane fits in the wing saddle?

Also the wing TE ribs do not taper to a feather edge as indicated so this would require changing the shape of the ribs which would make it even shorter.

Don't quite know how to proceed. Any suggestions?

Another photo of the TE.

I built this plane, so I'm not just guessing. You did it right. Sand the wing as if the ribs extended to a point. Do not sand the ribs any more. If you cut the sheeting like the plans show, you're all set.

Bax with Hobbico could answer this question- and probably will. He watches these threads too.

I think you are doing it right. You might wind up with a tiny gap behind the rib, It will still work.

This is a great question for Bax.

Brian

How do you think a Magnum XL91 4c would work in this plane? I'm just looking for a good-looking Sunday flyer.

I have only used Magnum 2 strokes before an have no experience with the 4 cycle models. However it is within the manufacturers engine range so should be ok. Just build as light as you can to keep the wing loading down.

I plan on using a Saito 125 in mine, more because I can also use that engine in other models that I own or plan to soon, than because of any need to power the extra to the max.

Looking at joining the wings. I have made up the wing jigs and presented the halves to each other. There is a large gap on the underside of the root ribs when the top portion is touching - maybe 1/8". I used the rib guage to set it up so I had expected a much better fit.

I wonder are the ribs supposed to be perpendicular to the spars when flat on the board or is the rib jig supposed to set them up so that when the dihedral is in the ribs are vertical? Alternatively I have use the rib guage from the wrong side - if this is the case the instructions did not even mention this.

Anyway, I will need to sand the root ribs/spars to obtain a stress free gap free glue joint.

Andrew,

Thanks for posting your problem with the wing "root" ribs. I'll be sure to pay close attention when I am at that stage to try and prevent it from happening to me.

I did a once through on the build manual (dowloaded from the website) before I bought mine. But that was not enough to have an Idea exactly as to what could be going on or if the root should be perpendicular to the spar. I wonder if maybe the ribs bowed a little on you when sheeting the top? Try running a straight edge down them from front to back and see if you can see anything showing up.

By the way, I received mine yesterday. I'll get to it as soon as I can.

Good Luck

The ribs are square to the spar and are straight front to back and top to bottom.

The issue is that when they are set at the correct dihedral the upper spars touch while there is still a gap of about 1/8" on the bottom spar.

What is the point of having a rib guage if it doesn't work - or if the instructions do not tell how to use it!

From my experiences as the wing is built bottom up when building the top of the root rib needs to be farther away from the tip than the lower edge of the root rib. To acheive this the rib guage needs to be inboard of the wing as the angle on the guage is about 91°.

A 2° offset angle will lift the wing tip spar by about 1" I will measure up latter and post what the angle should be for the dihedral, then when you press out your rib guage you can sand the correct angle into the appropriate edge.

What I have done is to set the wing onto the wing jigs and then to sand using a vertical sanding block.

This is just a question but I have seen this on some plans and not on others. If you look down at your plans and look at the spars is there a doted line running across the top of the spar?? There was nothing at all mentioned about the angle for the root ribs?? Nothing there for the degree of offset?? Just wondering. Most the time the GP kit instructions are so well writen they leave little to think about, I don't know why they would miss something like that.

Double checked plans and instructions. no mention of any angle on root rib or dotted lines on plans.

Hope to get a chance to glue together later - family commitments et al.

Just a note that the dihedral angle is around 3 degrees, the rib guage is between 89 and 90 degrees, probably supposed to be 90 degrees.

Confused on this one as it is surely not correct as is. Anyone else built this kit noticed this issue?

Hey, hows the build coming along? Im looking forward to more pics.

Build a little slow - familly responsibilities this week.

But I have managed to get a good fit on the wing joint so I will glue that this evening and post some more pics.

Went through the manual again yesterday noy reference on root rib angle but it does show using the rb guage to set the end points of the spars at the root. I measured and calculated the dihedral angle based upon the wing jigs at 2.7°. This implies that the rib guage should have an angle of 87.5° - mine does not. Would really like to hear from other GP extra builders on this one - for furure reference.

Build a little slow - familly responsibilities this week.

But I have managed to get a good fit on the wing joint so I will glue that this evening and post some more pics.

Went through the manual again yesterday noy reference on root rib angle but it does show using the rb guage to set the end points of the spars at the root. I measured and calculated the dihedral angle based upon the wing jigs at 2.7°. This implies that the rib guage should have an angle of 87.5° - mine does not. Would really like to hear from other GP extra builders on this one - for furure reference.

Andrewmc, great choice and yer doing a great job. I built one last year. A few tips. You want this thing light. I got mine down to 7.3 lbs. I'm running a saito 100 (pumped) on 30% heli. The vertical is BANGIN! I went with 5245 mini digital on ailerons and elevators (split) and a 5625 on rudder, pull-pull 2-56 (light...)

I lightened EVERYWHERE. The wing on this thing is built like a tank. You can drop a surprising amount of weight by carefully removing here and there.

The elevator/stab on this plane is very sensitive. In hindsight I would have moved the hinge line forward 1/2" cut 1" from either side of the elevator/stab and added some counter balance. Not a lot of counter balance and in fact hidden like a funtana so it is not overly touchy at high speeds.

Be careful on landing. mine liked to rock a bit. I was all over the ailerons keeping it level on approach, mostly when it got about 5 feet over the runway and down and it gets a bit mushy on approach so keep the power up a bit and don't float it in as it will drop unexpectedly. This plane does the best lomkavecs I have ever seen.

Be sure to beef up the landing gear mounts. I did with mine and it is a good thing as mine survived a drop of 3 feet with only a slightly bend gear. (i.e. don’t slow up too much on landing.)

Hi twn

Nice colour scheme, and 7.3 lb is a really goodAUW, so I guess I don't need a fibreglass bandage on the wing joint then

Happy with the wing fit and took the plunge and epoxyed all together. I think I used enough clamps

Oh also, this screwed me up pretty good. The plans show 1/2 degree of downthrust. I had to put it to 1.5 degrees of down thrust to get the flight right. She floated like CRAZY with .5 degrees of downthrust. I over shot the runway 3 times trying to bring her in. 1 click of power too little and stalling 2 clicks of power and she was climbing... It was a bear on the first flight. Once I set the down thrust right she was a totaly different plane.

Oh and no matter what I tried she always liked to pull a bit to the right on the uplines. no amount of reduced right thrust would fix it. I just got use to it and corrected with the rudder in flight.

The pumped saito 100 was a perfect match on 30% with a 15-6 MA. I had my imac buddy put her though his routine, rolling circles, rolling loops, knife edge, slow rolls, 2, 4, 8 & 16 point rolls, walls etc... She does it all. Hover was ugly though but more than enough power. Good pull out at that weight but not space shuttle blast out. She is a nice plane but I would prefer more of a mid wing with no dihedral. More like a 260.

Sounds to me like you want the Goldberg Extra 300!

(Sorry Andrew!)

Brian