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Goldberg Extra 300

Old 11-04-2011, 06:17 AM
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Default RE: Goldberg Extra 300

Well, I'm still WAY behind the power plant of most you, but I've just swapped out the Evolution 61 2-stroke for a Magnum 91 4 -stroke in my very old and tired GP Extra. The Magnum bolted right on and even the fuel lines matched up. I did have to modify the throttle pushrod and carve out the cowling openings a little more, but it was pretty easy. The exhaust and muffler are inside the cowl and a rubber deflector puts it cleanly (as clean as a nitro can be anyway) out the bottom. I'm hoping to test fly it this weekend. The plane originally had a Saito 91 on it (but with no cowling) and I removed the motor for another project and left the airframe hanging for a long time. I next put an OS 61 2-stroke which worked very well and then had a better home for that and replaced it with the Evolution which worked okay.

Anyway, it's still alive and on to a new chapter. Maybe a strip down and recovering will be in order some day.

Jaybird
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Old 11-04-2011, 06:37 AM
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Default RE: Goldberg Extra 300

Sounds like a power plant route several of us have taken with our Extras over the years, as during my Extra's 16 year reign it has had no less than four engine transplants, starting from a ST.61 and finally ending with 23cc gasser. Sure hope the Magnum performs up to your expectations.

Karol
Old 11-04-2011, 06:46 AM
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Default RE: Goldberg Extra 300

Thanks Karol. I'm using the manufacturer recommended APC 14 x 6 prop and 10% nitro fuel for the break-in period. I've run a couple tank fulls through it on the stand and leaned it a little at a time. It's got good pull and should be an interesting change from the 2-stroke. I also bought this engine along with a very used Saito 91 that wasn't running at the time and a new ASP .61 2-stroke for $200. The ASP came in handy as the needle valve assembly on the Magnum was worn and the ASP needle assembly is exactly the same so I swapped them out. I later found replacement parts at the hobby shop so now both are good. I took the Saito apart and realigned the cam gear and then checked the valve clearance and now it's running well too. It will need new bearings at some point but it will work for now. So, I figure cost wise I've done pretty good!

It's suppose to be sunny and in the high 40's this weekend...yeehaa!

Jaybird
Old 11-04-2011, 07:02 AM
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Default RE: Goldberg Extra 300

Don't forget to post an update as to how the first flights went. Sure hope the sun shines for you.

Karol.
Old 11-04-2011, 08:36 AM
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Default RE: Goldberg Extra 300

Nice clean job you did, hope it works out for you. I did notice the spinner you are using. You may want to give some thought to getting a different one. I have seen a lot of those break when starting the engine and turn into a grenade. They scare the heck out of me. You also got a pretty good score on some used engines. Glad you got them running.
Old 11-04-2011, 08:43 AM
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Default RE: Goldberg Extra 300

Thanks. I only had to open up the side hole a little bit in the front to clear the pushrods and some in the back to clear the cooling fins. There is really good airflow through this big cowl so it should like it in there.

Thanks for the heads up on the plastic spinner. I've been thinking of replacing it with an aluminum one after these test flights.

Jaybird
Old 11-04-2011, 11:08 AM
  #1332  
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Default RE: Goldberg Extra 300

Mine is side mounted too and I have a Pitts muffler that sticks out the bottom. The complete bottom of the cowl is cut out so I have never had a heating/cooling problem. Those spinners tend to get the plastic inside where the screws go into cracked and they let loose. I no longer will pit next to anyone using them. When they let go they really toss a lot of plastic. My LHS stocks a number of different makes of spinners and I tried the Magnum spinners he got in. I like them every bit as much as the True Turns and for a lot less money. I had a box full of plastic/nylon spinners with the aluminum back plate and they mounted like a True Turn. Those worked out very well and I never had one come apart. I think? They were a Tatone?? Been a while. I liked them on my gassers because they were in different colors and I hand started those engines.
Old 11-06-2011, 10:31 AM
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Default RE: Goldberg Extra 300

Not sure what the problem is, but the Magnum didn't perform as well as I had hoped. It was 46 degrees or so with a strong north wind, but sunny and clear skies. The Magnum started and ran fine after I got my refueling valve unstuck and I let it warm up and kept leaning it out slowly, but there was still a lot of exhaust smoke...as the crowd standing downwind made a point of! The first flight I took off down wind as into the wind would have me heading straight into the corn stalks across the road at the end of the runway and I wasn't sure what the performance would be. Good choice as it staggered into the air and I turned back around and landed. I reset the high speed needle again and got a little more power and second attempt was better, but not as good as I wanted. I landed and switched to 15% nitro fuel and that helped and then tried an APC 13 x 6 propeller instead of the 14 x 6 (manufacturer recommended) and got a little more each time. Still not what I had hoped for.

I'll check things out and do another bench test to see what going on.

Jaybird
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Old 11-06-2011, 11:33 AM
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Default RE: Goldberg Extra 300

It's hard to say what you thought the power should be but the .91 four stroke is not a fire breather. Built stock the plane is not a brick but it's not a light weight ARF either. If you start the long process of reading the thread you will see that the plane has been flown with a lot of different size engines from gas to glow. Mine is perfect with the YS 1.20 in it, it lacked a bit with the OS 1.20. Your Magnum .91 will fly the plane as it was designed. Back then the engine of choice was a .60 two stroke so your in the ball park. The .91 is never going to give it the vertical that most of us crave but you should be able to fly the IMAC with it. My next one is going to be a scratch build so it will be lighter then the kit plane and I have been holding back my RCS 1.40 gasser for it. The little 1.40 is a very high performance small gasser and should give the plane that WOW factor.
You really do have a nice looking plane!! Prop testing may help solve your power problem. Look at some of the 14 inch 3-D props with a lower pitch but the 14X6 APC is what I end up with on most of my planes using the .91 but mine are OS.
Old 11-06-2011, 11:47 AM
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Default RE: Goldberg Extra 300

Gray Beard, If you build from the plans I have that were yours, use the Slimline Pitts style muffler. The Bisson will cause sleepless nights...I ended up splitting the bottom of the cowling and adding little 1/8" lite ply tabs with blind nuts inside for re joining. Then cutting a lopsided piece out of the right cheek for the muffler....Gary L. Sr.
Old 11-06-2011, 12:09 PM
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Default RE: Goldberg Extra 300

As I recall even with the ST.90 engine my Extra did not have the amount of 'umph' up front that I wanted, but switching to a EI G23 gas engine did the trick for me.

Karol
Old 11-06-2011, 02:05 PM
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Default RE: Goldberg Extra 300

I have an OS 91 4-stroke on a 9-1/2 lb Great Planes Super Skybolt kit built biplane with an APC 13 x 6 and it really goes and has great vertical and level flight performance. It's one of the fastest planes I have and really scoots at full throttle. This old (and very worn) Goldberg Extra is just over 10 lbs, so yes I was expecting performance similar to the Skybolt or at least on par with the 2-stroke .61. I haven't tached the two engines to see what rpm they are achieving for comparison but I did end up with the same prop and fuel. It was a lot slower in the air than I had anticipated but this plane flies great at slower speeds as you all know. I'll keep playing with it. I may try the ASP .61 as it has the same bolt pattern and I have the pitts muffler already from the Evolution motor that was on it.

It's funny, each time I bring it to the field there are always a couple of guys that get all nostalgic about the CG Extras they hae had and even in it's rough condition I had I guy offer to buy if I ever plan to sell.

Thanks for the compliment Gray Beard, but I've seen some spectacular looking planes on this thread that make mine look pretty sad. It did belong to a friend of a friend who flew it constantly for many years, so it's kind of fun to keep the old girl going. He had a Saito .91 four stroke in it when I bought it so maybe I'll try reworking the motor mount to fit the one I just picked up. Perhaps it would have better performance and I can put the Magnum in the other plane (BUSA 80" Eindecker with a Saito 80).

Lot's of winter projects now!

Jaybird.

Old 11-06-2011, 02:13 PM
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Default RE: Goldberg Extra 300

ORIGINAL: Gary L. Sr.

Gray Beard, If you build from the plans I have that were yours, use the Slimline Pitts style muffler. The Bisson will cause sleepless nights...I ended up splitting the bottom of the cowling and adding little 1/8'' lite ply tabs with blind nuts inside for re joining. Then cutting a lopsided piece out of the right cheek for the muffler....Gary L. Sr.
Those templates were given to me by Brian and his 5 year old son and traced from one of the old die cut kits. I haven't built from them yet but they should just be the same old stock plane I have built before. The cowls I buy are the extended cowls from Fiberglass Specialties and so far I haven't had any real problems cutting them to fit the muffler on several different engines that customers have used. I have been tols FGS was going to stop making the extended but guys on this thread have still been getting them. With the short cowl I could see some problems. I'm going to try to post a few photos. I have a YS 1.20 mounted in this CG Extra. The bottom was cut in 1988 more for cooling then anything else. The muffler I have for the RCS 1.40. Yes, it's missing the pipes but I will weld on a new set. The RCS is smaller then the YS but it is rear induction so I have to open the fire wall when I use it on any plane. It puts out a bunch more power then the YS and swings a bigger prop. Way stronger then my G-26 and light weight to boot.
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Old 11-08-2011, 08:02 AM
  #1339  
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Default RE: Goldberg Extra 300

It's been a while since I dropped in here to see whats been going on with the GB extras. I still have mine and will always have one in my line up. I feel it is one of the best flying planes ever made. I'll stick with the YS 120-SC I have in mine as it is, running a 16x8 APC it will go vertical untill I make it stop so thats good enough for me. The plane weighs in at 9.5 lbs I did the usual mods for the gear and front end fuse sides, the only other mod I did was to move the servos back some and add 2 servos to the elevators.
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Old 11-08-2011, 02:06 PM
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Default RE: Goldberg Extra 300

Hi Richard,

That's a really nice looking Extra you have there, and more than likely everyone who has ever had the pleasure of owning or just flying one will agree with you that it's one of the best flying model ever. So far I've done most of the mods mentioned in this thread to mine except for the twin elevator servos, and I have had several offers to part with mine but that's a definite no no for me. How old is your model as she looks like brand new.

Karol
Old 11-09-2011, 07:03 AM
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Default RE: Goldberg Extra 300

Hi Karol
Thank you, My extra is about 10 yrs old now, But I only fly it on what I call special times, it only was flown twice last season, but it has seen many days of flying in the past, I have sort of moved over to the larger gas plane's now so the Extra and many others spend alot of time in the hanger.

Here are a couple of pics when the plane was new, notice the smaller prop I had a 91 FX engine in it to start with, while it flew the plane ok nothing to brag about the YS made it a real Flying Machine.
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Old 11-09-2011, 10:44 AM
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Default RE: Goldberg Extra 300

I sure wish I had some photos of mine when it was fresh. It's still looking OK but it does have patches and tape in places. I keep saying I will strip and re-cover it but mine gets flown constantly. It is usually with me when I go to the field. The poor cowl is cracked and repaired but I haven't bothered to re-paint it or the wheel pants. When I have a plane that is still flying that well I hate to put it down for any length of time.
Funny, I got rid of my big planes and went back to 60 size. I did just build a 1/4 scale but the smaller planes just get flown more often. It's more of a hauling thing. Big planes take up a lot of room in the van.
Old 11-09-2011, 10:58 AM
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Default RE: Goldberg Extra 300

Your model in both sets of pictures look very much the same to me, darn good. Mine is 16 years old and like yours she only gets flown every now and then, and even though that is the case I still am constantly tinkering and giving her a going over. As she is now with the G23 for power I am quite pleased with the performance and figure that I am just about done with mods to her. If and when she goes to balsa heaven I will definitely build me another.

Karol
Old 11-10-2011, 07:55 AM
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Default RE: Goldberg Extra 300

HeHeHe Yeah I'm sort of funny about my planes, I do my best to keep them as new looking as I can. I even wax them at times to help keep the mono in better shape, plus it helps get the fuel residue off afterwards.
The pics don't show the little imperfections some hanger rash and some other road rash *L*
Old 11-16-2011, 06:40 AM
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Default RE: Goldberg Extra 300

Another one!!!, 90 % complete.

My wive is helping me, I am sooo happy!
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Old 11-16-2011, 07:07 AM
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Default RE: Goldberg Extra 300

Looking good,Your going to enjoy the plane to say the least. That is a real treat to have the wiffy take an intrest in what a person is doing. I know that my hanger would have alot less planes and engines in it if not for my wife and the intrest she takes in my hobby.
Old 11-16-2011, 07:17 AM
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Default RE: Goldberg Extra 300


ORIGINAL: Cyberwolf

" That is a real treat to have the wiffy take an interest in what a person is doing. I know that my hanger would have a lot less planes and engines in it if not for my wife and the interest she takes in my hobby."

Amen to that, as our wives at times really put up with a lot, or sometimes less so as to allow us to enjoy our hobby.

Karol
Old 11-16-2011, 07:22 AM
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Default RE: Goldberg Extra 300

I swapped out the Magnum .91 four stroke for an ASP .61 two stroke last night. It was pretty easy since the bolt pattern is the same and I already had a Pitts style muffler installed before. I had to put in a new throttle pushrod and add a hole for the carb mounted needle valve and it's ready to test run. I hope to try it this weekend.

Jaybird
Old 11-16-2011, 07:30 AM
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Default RE: Goldberg Extra 300

Don't want to throw cold water on your engine choice, but I don't think that you will be very impressed with the flight performance of your model with a .61 glow engine. It will fly it, but more than likely that's about all it will do. I went a similar route early on with my Extra, but after just 2 flights I swapped the ST.61 for an ASP.75, and then a ST 90, before finally going gas.

Karol
Old 11-16-2011, 07:36 AM
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Default RE: Goldberg Extra 300

I had an OS .61 on it before and it flew very well, better than with the Magnun .91. I had the ASP on hand from a recent swap meet so I figured I'd give it a try before anything else. I also run this plane on skis in the winter and have found the two strokes easier to run in cold weather. I don't have any gas experience and I'm not ready to invest in it at this point. Thanks for the input though!

Jaybird

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