Droiddr

HI all,

About a month or so ago, the guy that taught me how to fly called me and said he had 2 kits to sell. The first was a great planes Giant aeromaster, and surprise the second one is a Goldberg extra 300 (both kits untouched). I bought both kits for 400$. I was told by others it was a fair deal.
Anyways I read this whole thread and took many notes. As I started asking questions and reading, all you guys won me over on the quality of the plane. So I think I will keep the original parts as templates.
I hope I can pester you guys with questions here?
This is what I plan on doing:

1- Use the original parts as templates and make my own. Mods would include not making the cutouts just behind the firewall in the fuse sides (thanks Karolh). I also read a few times that the doubler should be extended to the firewall. I will ask and post a pic later on my intentions there to make sure I do it right.
2- Alu LG from TNT or another source.
3- DLE20 rear exhaust engine so that I can mount it upside down and have the exhaust down. ( no need for another muffler)
4- 2 standard servos (425bb possibly) for the elevator, as far back as reasonable to balance the plane.
5- 1 bigger servo for the rudder, possibly a hitec HTHS625MS, Super speed metal gear.
6- 2 aileron std servos
7- put a dubro 16oz tank at the CG.
8- Try and see if fiberglassing the stock cowl a little will make it last.

Right now I am finishing the repairs of my 4* 40, will retrofit my greatplanes extra300 40 sized. I will be finished in 2 weeks I think. I want to be an expert on these 2 planes before I dare touch the CG extra.
I plan on starting the CG extra build this month, hopefully ready for mid-summer.

You guys are great to make this super thread!
Best wishes!

bigal126

My Feedback: (18)

A 16 oz tank is too big for a 20. 10 or 12 ounce will work fine.
I would extend the rudder about a 1/2 inch at the top and 1 inch at the bottom.

Droiddr

Hi Bigal,

I sent a reply to your message about the LG you have. You mentionned your messaging on the site is flaky. Do you still have the LG?

Have a great day!

karolh

Sounds like you got a good deal there and your list of things to do seems to be just about right to me, however if you plan on using a gas engine for power keep all the knockouts in the fuse sides forward of the front wing saddle former in place for added strength to help manage the vibrations of the gasser. The area just forward of the wire l/gear location has been identified as a possible weak area so an additional ply fuse doubler from that former going forwards into the tank compartment is suggested.

Droiddr

Thanks for the reply.

Since I am probably going to do templates, I will not cut the knockouts from the fuse sides and leave the tank area 'whole'.

As for the landing gear weak area, I have an idea, really not sure if it is a good one: When I cut the ply doubler that is also the wing saddle, why don't I have it expand forward from there to double the whole tank area? Is that what you meant?

Gray Beard

My Feedback: (-1)

That really is a fair deal, last time I found the giant Aeromaster kit the price was $200.00 and that is what they were selling for when they were discontinued. Both kits for $400.00 is right in the ball park for todays prices. No one got hurt. To make templates you can just use all the kit parts and trace them onto butchers paper and still build the kit. Your call. The main thing is to have the templates. I have a set but they aren't the best. Make a template of every part though, even the little things. That way you can get a copy of the templates at Kinko's and share. As bad as mine are I have shared with three other people. I would like a better set myself.
My bipe days are over but I still have regrets about not being able to build the giant aeromaster. By the time I came up with the 200 beans the fellow had sold the kit. I lost out.

Gray Beard

My Feedback: (-1)

The only weak area in the whole plane is the fuse from the leading edge forward. It really isn't a weak area at all but the plane is an old design and was only supposed to have a .60 {or there about} engine. Modelers being what they are tend to use much bigger engines. It isn't a power thing as much as a weight thing. Mine has been in use for a couple of decades with a YS 1.20. Over time the fuse and doubler got a bit fuel/oil soaked and on a hard landing one day the front of the fuse fell off right at that point. Without going out and looking I think the doubler is just very thin ply? 1/16 or 1/32? From then I I used a better ply, 1/8 aircraft ply and made the doubler longer. I have built a lot of the CG Extras for other people and done this and to date none of them have broken. I still haven't ever used a gas engine in one but Karol has been flying his for a long time too without any problems. Last one I built used the YS 1.40 sport engine and it's still flying, that was 7 years ago and the only mod I made to the kit.

karolh

Well Gene (Gray Beard) beat me to responding, but just do as he suggests and you should be good to go. My Extra started life first with a ST 61, then ST 75, ST 90 and now has Zenoah EI G23 and so far shows no signs of falling apart .... lol.

opol

My Feedback: (1)

big cam you have chosen a very good aircraft. I have a os 90 in mine and it will do most any thing you want. a os 108 would make it awesome. the only mod I did was on the cockpit floor. roll iy over and glue dowels in the grooves. easy to build. have fun. opol

j41captn

My Feedback: (5)

Droiddr, currently I'm flying the Goldberg Extra 300 with a DLE20 and it flies great. When I built it I originally used a Magnum 91 fs and it flew good but lacked power. The DLE20 made it come alive. Take the stock cowl and wheel pants and throw them in the trash and buy fiberglass parts from Fiberglass Specialties. You will understand why if you don't. The vibration from the engine will destroy the ABS cowl in less than 10 flights. The DLE sips fuel so I use a 10 oz. tank and after a 7 minute flight it uses about 1/3 of a tank. I also put the tank right below the wing for proper CG. I did replace the LG with aluminum and a little higher for better prop clearance. I do use standard high torque Futaba servos (F3010). I also use the Futaba F3010 servo for the rudder pull-pull system and that also works great. It will do knife edges all day. Have fun, you will love your CG Extra 300. Dave

mentor3434

My Feedback: (1)

My 2 cents. I am currently building (framed up) a CG Extra 300, purchased a new DLE20RA for the plane and laying the engine on the plans attached to DuBro aluminum beam rubber mounts it appears that the engine will protrude forward of the stock configuration about 1/2" so hopefully I can move the cowl forward enough to compensate. I plan as others suggested gluing back the cutouts forward of the leading edge and will probably cross brace with carbon fibre tube. I agree the stock cowl and wheel pants are junk so I opted for the fiberglass cowl and have purchased a carbon fibre landing gear that is a little longer, for prop clearance and will tilt the mount forward about 1" of stock to keep the nose out of the dirt. I am still looking for wheel pants and what seems to be a good fit would be the 60 size pants for a U Can Do (fiberglass) for $21 or fiberglass made for the plane at $40.. Undecided about covering but leaning toward fabric covering and paint, yep I know more weight, but I want colors that are not available in plastic covering material.

Droiddr

Hi,

Gray Beard. Thanks. My first idea was to use the kit as a template, but that is more expensive of course as you have to buy all the wood to build. I was thinking the parts themselves are the most precise templates and you can trace directly on new plywood/balsa.On paper, what is the best way to trace to make your parts precise? A very thin ballpoint pen? A very thin graphite pencil? Then you have to photocopy, cut the parts from the paper, lay on the wood and cut from there. Have you seen any issues with dimension precision using paper?
I may have a third option, please give me your opinion. I talked to the draftsman at work and was asking him about materials I could use. He gave me some old mylar sheets used for plans we have not used for years. I wonder if tracing templates from them would work? It may be possible to cut them and trace directly on wood and also be able to reuse them. Will have to try.
Anyways, if I do traces on paper or mylar I could share them if desired.

J41, Mentor: The engine I bought is the rear exhaust DLE20 to avoid buying another muffler. Is it worth the effort to fiberglass the inside of the ABS stock cowl?
I did not realize what the consumption of the engine was. I guess that 16oz tank is overkill.
Mentor, what is the part number from dubro on those mounts?

Talk to you later. You guys are great.

Cyberwolf

My Feedback: (4)

Just some food for thought.
Myself I would stay away from the rubber iso dubro mounts,the rubber will not hold up for very long using any large engine and need to be replaced way to often.
While an iso mount is a good idea in some cases, I feel the solid mount is a good option for the GB extra. I also realize that a gas engine will shake more than a glow will and increase the need for new gromets, but like grey beard I also run a YS 120 in mine and they don't idle all that smooth and so far I have never had an issue. Also I would bet the 1/2 over hang mentor 3434 mentioned would go away with a different mount. Myself I have never had much luck in moving the cowling on the extra very much.
A person can lay the engine on the plans and see if there is going to be a problem before one starts the build, then make the necessary modifications while they can.
Tracing the wood to wood would be the closet thing to the original if you sand the line away when done, other wise the part will be slightly over size. In most case's not a problem but stack up can sometimes cause some issues.
Good luck with your build ,I feel the GB extra is one of the best flying planes every designed for a sport acrobatic type of plane It's not a 3-D type plane. Oh and I second the rudder mod that big al mentioned,helps alot in KE flight.

mentor3434

My Feedback: (1)

It should be the DuBro 688 for a 120 engine. I originally intended to use a OS 120 4 cycle but changed my mind. I set just the DLE20 on the plans with about 1/4" clearance from the firewall and that is where the engine protruded out of the cowl about 1/2". Real world, I have yet to see how that all pans out. Before I drill my motor mount, I have yet to find what DLE recommends for the spacing between the end of the carb and the firewall, does anyone know for sure?

Gray Beard

My Feedback: (-1)

OK, just for grins I got up on the step ladder and measured things. First thing I did was take a photo of the DB mounts I use on my small gasser. This is one of the original RC Showcase 1.40 22cc engines. I just discovered they were made by Moki. It pulls better then the DLE 30 though so it's a real ball of fire, just small. I have never had to replace the rubbers on the mounts and they work great. However, last CG Extra I built had a YS 1.40 in it and I used the anti vibe mount made by Jtec and so far it is the best anti vibe mount I have ever used. Just a bit different and needs some prep work to use.
The FGS cowl is 11 inches long from the top to the front of the nose. If you need more room with the rear induction then just cut the fire wall big enough for the carb to fit inside the fuse a bit.
I have used the stock cowl and pants and glassed the inside. It helps but they still come apart over time.
The plane uses standard 60 size pants that are 8 inches long. You can usually get them at any good hobby shop for a lot less money. I pick them up at swap meets and have a couple sets. The ones on my extra are FGS but when I bought the cowl years ago I got a deal on the set.
My shop is really over crowded right now so I had to leave the plane hanging while I took the measurements.
The rear induction carbs like about 1/2 inch for good air flow. If you don't have it bring out the hold saw. Not a big deal, have had to do it more then once. On one plane I had the carb inside the fuse and boxed it in and made the box an air cleaner, worked great. Just make sure you have access to the needles. I once forgot about that little point!!

Cyberwolf

My Feedback: (4)

I'm glad you never had a Durbo mount groment fail Gene , but I have and it didn't take long less than a gallon of fuel and I went thru 2 sets of gromets, plus the fact I didn't really see much isolation to begin with using one of the things.
It is very easy to tell if the rubber is shot on the Dubro type mount, for starters just grab the prop and lift up on the engine,if there is an excess of movement there shot in the butt, you will soon see the plane start to climb under full power,which it did not do when things were new and tight. I have had more than one of these POS and I just tossed the last one in the garbage last week. They couldn't handle a 120 Webra speed engine or an OS 160, Plus the extra unwanted length doesn't help either. Maybe if they had a nose ring things would be different. From now on if I don't make my own Anti vibe mount I will use a Hyde mount, they hold up and work well.

Rubbernecker

My Feedback: (22)

[QUOTE=Droiddr;11775434]Hi,


Is it worth the effort to fiberglass the inside of the ABS stock cowl?

Don't waste your time on it. The ABS is junk. Not even sure why any kit manufacturer includes them. I tried it years ago with mine and as stated, it won't last very long. Just get a fiberglass one from the get go. You will be glad you did.

John

Droiddr

Hi,

Well the guy that sold me the kit found out he had a fiberglass cowl somewhere and will sell it to me for a fair price. So that solves that.

I am not sure what mount to use then. There seems to be disagreement about them
Would a standard mount be a bad thing? I have an aluminium one from dubro, plus a standard one from great planes for 1.20-1.80 size engines.

Later!

karolh

Either of the mounts that you have can work but I tend to prefer the nylon composite ones.

ThunderBoat42

My Feedback: (1)

Glad to have found this thread. I was just given one and it's maybe 80%. It does have the aluminum gear and fiberglass cowl and w pants. Now it has a lot of rash from all the years and some broken parts such as ribs and the horizon tail is busted on one side The cowl is warped from being in a box. I don't know it it can be used. I have a ys 120 that will work perfectly but lord it looks like it will be more work than starting over. Probably not but repairing the horizontal stabilizer will be a pia.

Gray Beard

My Feedback: (-1)

The cowl should work out, the fuse helps shape it, if not maybe a soak in some very hot water? I don't know, never had to straighten one out. Best thing to do is just strip all the covering and go through it and do the repairs. It's a very easy plane to cover so not a big deal. I hate doing repairs but if it becomes too much work for you I will pay shipping and take it off your hands for you. Dang I'm a nice guy!! Remember, you saw it first here!!

OldScaleGuy

My Feedback: (2)

Bill, depending on the condition of that horizontal stab you may be better off to scrap that one and build a new one. One of those can be framed up and sheeted very quickly. I flew mine at the Mint Julep scale meet this past weekend. It is a great plane, you will have a lot of good flights with it.

karolh

The Extra is such a great flying model you will be glad you made the extra effort in getting her fixed right.

Cyberwolf

My Feedback: (4)

Yep I pulled mine out of the trailer last weekend and flew the snot out of it. What you have been told is the truth, I call mine the little plane that thinks it is a 35% because of it's manners and behaviors in the air, If built correctly a person can get many hours and years of good fun flying time from these planes. Good luck with your build

Droiddr

Hi all,

I have been working over the last couple of months actively on my first CG extra.
As I have posted before, I have used the kit to trace and cut new parts.
Here is mainly what I did different from the kit.

1- I found some 1/8 ply with 3 layers made out of the same or similar wood as aircraft ply. Some sheets have a couple of patches, but they are not a huge issue. Each sheet is 30x60 inches and cost me less than 10$ each. It is about 70% heavier than lite-ply but MUCH stiffer. I cut all the kit's ply parts from that. I made the lightening holes a bit bigger to save a little weight. The ply parts will be heavier than the original kit parts, but much stiffer. I expect my build to have 1/2 pound or so more weight from that. This is a bargain vs aircraft ply at 40$ for 24x48 inches. When I compared my fuse sides with the kit`s, they were much stiffer and felt more solid.

2- The doublers I modified. I added an extension that goes to the firewall and around the wing leading edge, did not make lightening holes in the tank area. The other mod was accomodate a ply plate to affix the LG. basically I added a very small trippler to add gluing surface for the LG plate. The former just in front of the LG also supports the plate.

3- The wing formers were cut from tracing the originals. I did not cut the kit`s lightening holes, but added 1 smaller circular one to pass the servo leads. I also cut the holes down to the end of each wing in case I want to mount something there.

4- The DLA20RA`s carb is very close to the firewall so I will drill a hole in the firewall to help it breathe.

5- I modifed the aileron servo plates. As suggested in this thread I did not put a plate in the wing as per the instructions. I mounted the servo on the plate that covers the wing port, using 1/8 ply and mounted with screws into ply supports for the screw holes.

In the 2nd pic you see the mods to the doublers. Do not know if its best like that but will add fair reinforcement.




I had a couple of questions before I continue.

- Should I cover the stab and fin before gluing to the fuselage?
- The clearing of the carb intake to the firewall is about 1/4 inch. I do not know if it is enough, but I intend to make a hole in the firewall at the intake location about the same diameter as the intake. Is this a good idea?
- Should I locate the ignition and battery in front of the firewall or back? does it matter? or should it be only determined by what is most convenient? An option would be to mount them on the tank tray supplied in the kit ( I will put the tank below the wing since I am using gas).
- Should I use baffles in the cowl to redirect the air on the cooling fins as the piston will be upside down? Would the airflow exiting beneath and at the back of the cowl be enough and force the air through the piston area anyways?

Any comments or suggestions would be very welcome!
Best wishes!