youngun

I just started a Goldberg Ultimate kit.

The engines called for on the box is a .60 2-Stroke OR a .90-1.20 4-Stroke

I noticed on the plans a K&B .65 Sportster 2-Stroke engine is used, which, I think, means Dave Patrick probably designed the model for this engine.

I've already read many recommendations by the 3D boys for the most hugest engine a person can possibly shoe-horn into the plane.
I'm not interested in that here.[sm=tired.gif]

What I'm looking for is for any information about anyone having put a K&B .65 Sportster, or failing that - a .60 size 2-Stroke, in one of these and how it performed, as to normal, scale for an Ultimate, flight.
example: Normal loops, rolls and such that a full scale ultimate would, and could do.

I don't want to make a helicopter out of it, or out of sight vertical or any of that hanging on the prop junk. [sm=tongue_smile.gif]
(no DA 200s in a .60 size plane please)[sm=bananahead.gif]

I would just like to know, hopefully from someone that tried it, how a .60 size 2-Stroke, preferably a K&B .65 Sportster, performs in one of these planes and maybe how much it weighed when completed, if that's known.

edited for:
I tried doing the product link with this thread but it didn't work.
So here's the link to the Goldberg Ultimate user reviews
[link=http://www.rcuniverse.com/product_guide/kitprofile.cfm?kit_id=932]Carl Goldberg Ultimate user reviews[/link]

MinnFlyer

My Feedback: (4)

The first thing to remember is: A manufacturer is going to picture whatever engine they sell in their plans. If they don't sell engines, they will use the engine of whatever company they have an agreement with. Example: Great Planes just bought Goldberg. If that lit came out today, it would be pictured with an OS 91 or 120.

In any case, yes, a K&B 65 will pull the plane nicely. It won't be an aerobatic gorilla, but loops, rolls, cuban 8's - sure

Norm Nestie

I know that a LOT of guys recommend huge motors for this plane, BUT, I flew a couple of Ultimates with a Super Tiger .75. I think you and I fly alike, and the .75 was just great with a 13x6 APC. I think you'll be happy with the .65 and right prop. FWIW

youngun

MinnFlyer,

I know you have a tremendous amount of experience and general knowledge about RC aircraft, so is your post about the K&B .65 maybe based upon having seen this combination fly, or, maybe on knowing the power of this engine? I know you have at least one Ultimate (or had), as well as the Super Skybolt, so you know the Ultimate design and its flying characteristics. (hope there still around and in good condition)

Just wondering .... You seem to be confident in your post that the .65 will work .... And that is encouraging.

Obviously, by this thread, I would like to use the .65 ... but I do have a Webra .91 and a pitts muffler for it that could be used. But that is considerably more weight than the K&B and I believe the Webra would use a lot more fuel, requiring a bigger tank with more fuel and even more weight again.

You see where I'm going here. I want to keep the plane light as possible too.

In other words - If the K&B .65 will fly the plane about as good as the Webra - why add more weight and use more fuel?

By the way - I wasn't considering any other engines for this plane - at least not yet.


Norm Nestie,

I put one of my K&B .65s on my super sweet stick while I was trying to round up a ring for the Irvine .61 that had been on it since day one. The one I would use on the Ultimate is still new in the box. So it isn't worn out or anything.

I considered the Irvine to be a powerful engine when it was healthy, and thought the K&B would not be any comparison to it.

Wrong - That K&B fooled me. It makes its power at a lower rpm than the Irvine, but its ability to swing a bigger prop was amazing, compared to the Irvine. And yes your right about the 13X6 prop. According to my tach, mine swings an APC 13X6 about the same speed as a 12X6 which I couldn't figure out - unless its the porting in it that is doing this.

But the Irvine, with an 11X7, will out-turn the K&B, with an 11X7, when the Irvine is in good condition. The thing with that K&B is - it will turn a 12X6 or 13X6 about as good (not absolutely the same) as it will an 11X7. The Irvine wouldn't do that. Something strange about that .65. But what ever it is - I like it.

However, the only Ultimate airplane I have ever had is a little foam E-Flite profile electric. It flys fantastic! And is one reason I want this Goldberg. The thing is - I don't know what to expect this Ultimate to need in the power area. Also, I don't want to break the bank in building or flying of it - So, the desire to use a more thrifty engine.



By-The-Way .. about the ring for the old Irvine .... I found a guy (I think his name was Frank Bowman) that makes rings for old engines and he had some already made for the Irvine. That gives new life, or extended life to this engine. It was good and will be again. If anyone is interested in his rings, I'll try to look up his contact information for you. Just post that you want it, and when I find it, I can ether PM or email to you.


Thanks for the replies!!

youngun

Off topic here:

Mike ... I watched your covering videos yesterday or today (short term memory goes when you get old - be fore warned )
Anyway - Great Job! Not only on the wing, but on the videos themselves. I did pick up a few things from them.
A question - When the covering joint is out in the open wing bay as in the videos - With your method, does that joint seal? Or if not, are there any negatives like fuel seeping in the wing there?

I didn't see that mentioned in the videos - or I missed it - one or the other.

Not24

My Feedback: (1)

I like where you are going with this, but I have some things for you to consider. I built one of these a few years back. I built it per the plans all the way. I kept the weight as low as possible by using mostly CA and very little epoxy. My engine was an ASP 1.08 with a heavy Jtec pitts muffler. My prop was a 15-6. The model came out with an aft cg and needed a little nose weight. I hadn't heard of 3D back then, so never dreamed of hanging it on the prop. The model weighed 9 lbs and flew very well. It had a fairly good glide and slow landing speed at that weight. Since the demise of that model, I had thought of building another one and going with a light weight engine. I think the tail may need to be lightened to make a small engine balance. If the model could be built at 8 lbs, the smaller engine would fly it just fine. If it weighs 9 lbs, it needs the power to fly well. Personally, I like the SuperTigre G90. That's what I would use if I were to build another one. For a 90, I would look for 8.5 lbs. As for the 65 sportster, the lighter you make it the better. The Ultimate is a fast biplane that climbs as good as anything in its class. To make it fly scale, you'll need a good thrust to weight ratio. 3D flyers like 1.5 to 2:1. If you get 1:1, it would be very scale. The danger in doing this is that we don't generally fly with a scale power loading for safety's sake. It's always nice to have more power when you need it, and you can always throttle back a bigger engine to save fuel and fly more realistically. I've had several k&b engines and I have found them to not be terribly powerful engines. The Tower 75 is lighter than an OS 61 and almost as much power as an OS 91fx.

youngun

Not24,

Nice post - some good things to think about.

You didn't say if you used the radio gear to balance the plane or not.
I usually try to leave the radio installation until last so I can move it to where the least additional weight is needed for balancing.

In this case, it sounds like the servos and battery need to be more toward the nose of the plane than where the planes show.

The Tower .75 might be and option. I'm sure it puts out more horsepower than the K&B .65. But, how does it compare in weight, and is it a high rpm screamer needing an 11 or 12 inch prop for its power curve or a torque engine that will turn a 13 or 14 inch 6 pitch prop with authority? In other words how does that extra power translate to prop turning ability?

About building light and trying to keep the tail, or any area, of the plane light;
I'm all for it and any suggestions are welcome. After having looked at the plans and the design, it's full of lightening holes already. The stab, elevators, fin and rudder are all built up and don't appear to have any excess material anywhere that I can see. The turtle deck sheeting is only 1/32 thin ply. So I don't yet know where that a person can shave off some weight in this design without seriously hurting the strength. Although, I'm still looking and open to suggestions.

I usually use ether solar-tex or monokote to cover with. But on this one, I'm plaining to use a light weight film covering.
That, and go light on any painting needed and do a good sanding job is all I can come up with for now.

Many questions that are looking for answers. I'm hoping the answers come as the work progresses.

It would be nice to come in under 8lbs and stay away from those big engines (.90 and above), if that's possible without replacing the wood in the kit.

Not24

My Feedback: (1)

Okay, here's more for you to chew on. You're right about not being able to lighten it up much. The only reasonable option for doing that is to maybe increase the size of the cutouts in the plywood fuselage. All the rest is as basic as it can be. Like I said, I built mine with CA. A friend just finished one and his came out at 11 lbs! He used wood glue throughout, added a smoke system and is running a Saito 1.50. I hate to say it, but his plane is a brick. The added power from the 1.50 doesn't help much in his case because the wing loading is too high. Landings are very fast and use our whole runway. To me, that's not how this model was intended to be flown.

The single elevator servo works fine. The model doesn't require lots of throw on any surface. The rudder needs a higher torque servo with ball bearings. The ailerons really need two servos in the wings. Mine was done with the single wing servo originally to save weight and it came loose from the model on flight #2. I was able to crash land and save the model.I went to two servos and flew it for another couple of years.

The steel wire landing gear works well at 9 lbs or less. I think a good option here is to get a CF gear to save a ton of weight. Aluminum won't save you that much. Problem is, this is forward of CG, so it would add to the balance issue.

You could use a CF pushrod assembly to drive the elevators. You'd have to design it yourself, but would be worth the time.

Replace the laminated firewall with one made from 1/4" aircraft plywood. It'll reward you after a season of flying. Also use the same approach on the landing gear mounts. You need hard wood here.

Paint the canopy from the inside to avoid the weight of a pilot figure.

The Tower 75 turns a 13-6 very well. I have no tach info, but it's not lugging. You may be able to go 13-7 or 14-6 on 15% nitro. I know some people say it's a revver and likes the shorter props. It does both very well. I know of the power of this engine because two guys have Ultra Stick 60's. One has the 75, the other has the 91fx. They both have unlimited vertical. Not much difference between these two, and the 75 runs much better. Those models weigh between 6 and 7 lbs. Based on that, I think even a 9 lb Ultimate would fly well on these two engines.

I'm very interested in your results. How hot are you on getting this thing done this flying season?

youngun

I don't expect to get it done this year.
My projects always take a lot of time.

I never worried about weight before this, and unfortunately, as a result, my planes came out on the heavy side.
Looking back on them, I can see why now - with reinforcing many things that looked weak to me, using heavy fabric covering material, painting and adding accessories. A lot of 'second guessing' the engineer that designed the kit. (still doing that, I guess, but in the opposite direction)

It sounds like this one is heavy enough already, without adding anything more to it.

I may look for more info on the Tower .75 engine. I remember many positive reports about it, but not the specifics, like the size props at what rpms.

The only solution I can think of right now is to put bags, or bladders in it, that can be filled with helium before flying. [sm=lol.gif]
Or maybe use aluminum nose weight to balance with, instead of lead. [sm=bananahead.gif]

Meanwhile, I'm still looking for any info about someone using that K&B .65 on the Goldberg Ultimate. Surely someone has done that, since it shows one on the plans.

youngun

About using carbon fiber material;

Where I live it isn't available locally and cost too much (from what I've seen on the internet) to mail order.
So until it is more readily available and the price drops - carbon fiber anything is out.

I did think about using a fiberglass arrow shaft (a friend has some left over from his archery hobby) pushrod for the elevators or maybe doing a pull-pull cable system on the elevators as well as the rudder.

Gray Beard

My Feedback: (-1)

Carbon fiber arrow shafts make great control rods, used to have A big supply of them until I made this move. Looked for them just this week and they were lost in the shuffle. Used air bags are carbon fiber and can be found at most wrecking yards. Some wrecking yards have gotten wise to it though and want money for them. Arrow shafts can be found at most parks that have archery for free. When they get nicked or hurt in any way archers don't use them again.
Just for grins take A look at the SK 90 engine. Low RPM and swings A bigger prop then most. I didn't put mine on an Ultimate but went from A MDS 68 to the SK 90 in an Aeromaster. Turned the Master into A real plane. Mine liked the 15X6 and 15X4 APC props. The Master is A very heavy little plane, can't remember the weight but it was around 9 pounds.
Just thinking.

captinjohn

My friend just got his second C.G. Ultimate flying. He has a Super Tiger .90 on it and it flys great. I know...I helped him on the first flight! Thanks Capt,n

youngun

I had forgotten about the SK engines. Since they swing a bigger prop, that would be a good one for consideration.

I remember the Andrews Aeromaster bipes. They flew great. Usually had a K&B.61 in them back then. I don't remember any weights for them ether. In fact, I don't remember people weighing their planes back then.

They just built it and flew it, however it came out.

Only bad thing I remember about them was the rubber band on wings. A good friend lost his when the top wing came off because of the rubber bands letting go.


captinjohn ,

That's a nice looking plane. Big smile on the fellow kneeling in front of it - he looks happy.
Did he weigh it? Just curious.

I've read that the ST 90 likes to rev. Do you remember what size prop he was using?


Thanks for all the info folks

FrancisPerson

Youngun,

I have a K&B Sportster .65 and it likes an APC 13x6 @ 10,700 RPM. Will handle a 14x6 just fine for Cub type planes. My Sportster was in a 7.7 lb Goldberg Tiger .60; very good performance but not quite unlimited vert. Take care to have the carb spray bar even with the centerline of the fuel tank.

TFF

The .65 is cheap to buy and is a good engine. You are not going to find alot on the engine now days as it has been passed by 4 strokes, and that plane/engine combo is pushing 20years old. My Ultimate had a Magnum 91 4 stroke and weighted about 8 lbs. It flew scale like. it is a high performance bipe, but mine would not 3D with my power; One of the easyest flying planes ever.

captinjohn

youngun: He did have a 8 pitch prop on test stand....it did not sound quite right. He picked up a 13X5 prop and it reved around 11400. I richened it to drop 200 RPM. It also makes for slower landing speeds and good climb-out. It needs a slow idle speed...it seems to be a real low drag ship...for being a bi-plane Capt,n

youngun

Thanks for the info folks.

My two K&B .65 engines were bought when they first came out, and were never used, until I put one in my Super Sweet stick this last summer.

When buying the Ultimate kit, and remembering all the posts I had read about the plane, I was thinking it would probably get the Webra .91 setting on the shelf as power. But after taking a look at the plans and seeing that Dave Patrick had the K&B .65 on it, I thought - Hey, if he has it on there - it may work !?!?! But I had better ask around first. (the reason for this thread) [sm=wink_smile.gif]


captinjohn ,

Those pictures are really nice! (you're making me want to get this plane built and go flying again[sm=biggrin.gif])

MinnFlyer

My Feedback: (4)

I have flown this plane with a Saito 150 and it was really too much power. If I were going to build one, I would use something like a YS 110 or )S 120, and that would be a LOT of power.

The added weight of the big engine combined with the smoke system are two factors that increased weight so much. And regardless of the weight, it shouldn't take the whole runway to land. Sounds to me like it was nose heavy.

So how am I coming up with my answer? My dad had one with an OS91 4-stroke. It flew well. I personally like more power, but it did fly well with the 91. So I surmise that the 65 will also pull it about equally as well. As I say, it will loop and roll, but you're not going to set the world on fire with it, but it sounds like you don't want to anyway.

Build it light. It really doesn't need reinforcing, so avoid the temptation. If you MUST reinforce something, use light-weight materials and go easy on the glue.

And BTW, when covering over an open wing bay, as I did in the video, yes, the joint completely seals.

Gray Beard

My Feedback: (-1)

The Aeromaster I have is A Great Planes. They made A lot of changes and it turned out to weigh A bit more then the older design. I think the old type flew way better but didn't look as good. No rubber bands though. The 68 MDS powered my Killer Kaos just fine but in the Master it was A total dog. The SK turned it into A real stunt plane. It's the first cheap glow engine I have been happy with in A very long time. To date not one dead stick, that alone is worth the price.
Minn, I have my YS 1.10 in my Mid West Hots and it dwells almost on the stupid side. I just love it!!!!!! Too much power seems to be just about right!!

captinjohn

Go with the Webra .90....you can always throttle back to save fuel. The webra should run on 5% glow fuel...another wat to save. Capt,n

youngun

MinnFlyer ,

Thank you for answering my questions.

I see what you're saying about the .65 being about equal to a 4s 90.
And you are right about my flying - I like smooth scale like flight, with a few smooth scale like acrobatics at times. I'm not one of those hot doggers that's constantly stirring the sticks.

Even after all these years, airplanes are still beautiful to me and enjoyable to watch fly.

About the covering video;
Now I'm going to have to try what you made look so easy in your video.
Might find a use for the heat gun after all.

MinnFlyer

My Feedback: (4)

I can't tell you how many times I covered without one. And I always thought, "I don't need one of those things".

Then I saw someone use a heat gun on a wingtip - I'll never cover without one again!

youngun

I still haven't fully decided about the engine choice - but after the info in this thread - I'm now leaning toward using the K&B .65

From what I can find out - the Tower .75 is a revver like the Super Tigre, And while it can turn a 13X6, it's happier with a smaller prop turning more rpms. Again from what info I have found so far.

The specifications for the SK 70 shows a 12X6 prop size and a weight of 25.56 oz. It being on the heavy side

The specifications for the SK 90 shows a 13X8 prop size and a weight of 25.96 oz. Less than a half ounce difference from the 70.

Interestingly, the Webra manual calls for a 14X6 break-in prop for the .91, and up to that size for running. But, at 670 grams (23.63 oz) engine only weight, (add muffler weight to that) I would just about bet that the weight (and the SK above) would be almost as much as a Saito 125. (the Saito is not in the running due to high cost) And fuel usage has to be considerably more than the K&B .65 - the .65 isn't as bad on fuel as the Irvine .61 was on my old Super Sweet Stick.

Decisions, decisions ...........

Not24

My Feedback: (1)

The ideal engine for the lightly built Ultimate would be a Saito 100. The tower 75 a powerful engine, but the flying experience is just so much nicer with a four stroke on this particular plane. The 100 may be too light for the nose, requiring some maneuvering to get the cg right. I know that the range specified on the plans is accurate. When you go to the front of the envelope, it lands fast and is really hard to slow down. Go behind the aft point, and you have your hands full. I flew mine on an older radio without expo or dual rates. I had to adjust everything for a good compromise.

I don't understand how people can label an engine a revver or a torquer. Every two stroke I ever had, had a wide range of props that would work. The best prop is determined by the airframe. It's true that two strokes like to turn up to get in their power band. I don't know of any differences there till you go with a racing engine that runs wide open on a little tiny prop with lots of pitch. I generally prop my engines for good power and not so much noise. Every engine has an rpm range that it likes to run at. I tend to choose the lower end of the power scale to help load the blades for good pull in all throttle positions. By using a little more pitch, the engine feels more torquey in the lower revs and still has good climb performance.

Gray Beard

My Feedback: (-1)

Timing and transfer port design changes the torque and RPM range of an engine.