youngun

Not24

What Gray Beard said

When you operate in the design power band and load, the engine gives its all, doesn't over heat or lug down.

Operating outside that power band or loading, while it can be done, usually has problems.

An example could be an SK versus a Super Tigre.
The SK seems to be designed for low RPM torque. While Super Tigre's have always been known as high RPM screamers.

As Gray Beard said - its the timing and transfer port design.

At least that's my excuse, and I'm sticking to it.[sm=angel_smile.gif]

Not24

My Feedback: (1)

I really don't want to be accused of hijacking this thread, so this will be my last post on this subject.

I have heard before that port timing has an effect on whether or not the engine has good torque or good top end power. I believe it's possible for people to assign a label to an engine just based on their limited experiences with that engine. In other words, I'd be more inclined to believe that there was some truth to what they are saying if they could back it up with some engineering facts or figures. I have done my own testing on the st2300 (which you may have already read), and I learned that what others say is not always the case, even when the company rep says it. ST recommends an 18-8 prop, which should turn in the mid 7's on the 2300. Well, it does, but the engine is not happy running like that. It is much more user friendly when it is propped to turn around 9000 rpm. Running it any faster doesn't buy you any more power, (i.e., thrust). It just revs quicker because it's not loaded down into the power band. Interestingly enough, and I know there will be some comments about the use of a temp gun, the engine's temp is directly related to rpm. The higher the rpm, the higher the head temperature. That's not what I expected to see at all. So, not only don't you gain power with the higher rpm, you also get hotter. In my case, the 2300 saw over 325 degrees on a 16-8 @ 9500 rpm. When propped for 9000 rpm, a 16-10 saw 295 degrees. The 18-8 was more like 255 at 7300 rpm. Granted, all this is just one man's opinion on one engine. I have a new G90 to play with next, and I'll start a thread for that engine also, once I get into the flight testing. So far, I have only run one prop, a 13-8, and it sounds and runs great. I'm wanting to run this engine with a lower rpm prop for noise reduction, because the model should be very over-powered with that engine. I love this website for exchanging thoughts and ideas. Thanks RCU!

turbo.gst

My Feedback: (8)

I think the perfect engine for the CG Ultimate is the 2-stroke ST 90. Thats what will be going in my CG Ultimate. BTW, the ST 90 can torque down very well. I will be using my K&B .65 in the Great Planes Ultimate .40 Keep us posted on your results.

turbo

Not24

My Feedback: (1)

I'd be interested in hearing your flight report with the ST90. I think it would be a great choice for the plane for a two stroke. The way they are making engines these days, it doesn't pay to go with a 61 or a 75, when the 90 is practically the same weight, and more powerful.

captinjohn

If I can find the Test report on the .90 Supertiger...I will post it. Seems like it had the ability to turn a very big selection of props. Also it had a lot of torque with right prop/props. capt,n

youngun

Don't worry about being accused of hijacking the thread.
Like you said - this place is great for exchanging ideas! So feel free to post your info.

Your results of your tests of the ST 2300 gives some good info. If you research the SK engines on this web site, you will find similar results - in that under-proping it caused some heat problems like you experience with the ST2300 with little, if any, improvement in power.

BTW - I don't want to sound like I'm against Super Tigre engines. I'm not. I like them just fine. The ones I have had, have given me great service. If I had to list my least favorite engine (just least favorite, not dislike), it would be O.S. Max. And the only reason for that is, I feel they are an over-priced mediocre engine - but that's just my feelings - not starting any campaign against them or anything. But everything needs to be used as it was designed to be used. Some are designed to swing a big prop at lower RPMs - like your st2300. While others are made to turn high RPMs - the engines designed for ducted fan use, or racing, come to mind.

The reasons I am leaning toward the K&B .65 is;
The model appears to be designed for it. (by an engineer/designer with an excellent reputation for his design work)
Being a biplane, I believe it would need a torque engine to fly it slower, but with pulling power.
And next is budget concerns - It would cost less to feed the .65 than the bigger engines
And still about the budget - I already have the K&B .65, as well as the Webra .91 mentioned, as well as a Super Tigre .75 (one of the first ones, an S75, with the round head.)

I have hesitated to use the Webra several times in the past for the same reason - from what I saw of their use, after I bought it many years ago - they were a fuel hog. I initially bought it to use in a Top Flite Corsair that had just come out. But things happened and I sold the Corsair kit but kept the engine.

I'm not sure - but I think that ST90 that keeps coming up here is a more powerful engine than this Webra of mine. This Webra was one of the first, if not the first, of the .91 size 2 strokes made.(when most engines still came without a muffler - and schnurle porting was new to model engines) The ST90 came along later. And being a Super Tigre, I would guess that it's a powerful engine, with the latest porting and timing. Again, just my guess.

If I had to buy another engine for the plane - I would have a long wait to get it. And might very well go with the SK because of the torque and price.

Just trying to explain myself a little here - not downing anybodies engine. Some other engine might be so good that it would be worth waiting till next year for it. Except for another 4 cycle - I've had enough of those.

youngun

Hi captinjohn,

If you can find that ST90 report .... I would like to read it. It would be a compliment to the issues of this thread

Who knows, it might be that engine that is "worth waiting for"

daveopam

My Feedback: (9)

Youngun, I don't have a report on the ST 90. However after running one for 15 years I can tell you it does not need to be a screamer. Whenever BAX answers a post he always uses a lot smaller prop than I do and turns up more RPM than I do. He is the expert and I have respect for his opinion. However sometimes there can be more than one right way to do something. That being said. my favorite prop for the ST90 is a 14x6. I have also ran a 13x8. The Tigre will turn the 14x6 on 15% nitro at 10,500 on the ground. To me this is not screaming the engine. I have several 4 strokes that turn close to 10,000 on the ground. For the type of flying you described to me you will be happy with the K&B. It will have enough power to do all you want it to do.

David

BTW I am going to post the pics we talked about here. I don't think I can PM more than one pic at a time. Also I will get to answer your PM this week. I just don't have the time today.

daveopam

My Feedback: (9)

Guys Yg and I have talked about the weak gear on the Ult. I told hime I had the gear from an old Goldberg Extra 300 in my shop. It looks like a good match for the Ult and it fits nicely. The wire is the same size but is stiffer for some reason. Could be the way it's bent or could be better wire. Either way i wanted to show the two wires side by side and show each of them on my retired Ult. I am also including a pic from when the Ult was new.

David

daveopam

My Feedback: (9)

OK the pics did not work. One more try.

youngun

daveopam

Thanks for the info on the ST90 and for posting your pictures.[sm=thumbup.gif]
The plane still looks nice sitting there by the flight box. Is that a recent picture too?
Looks like the gear would work, but it would sure look different.

Thanks for the opinion about using the K&B. I think the kicker for what engine to use is probably just what you said about the way a person flys.

That 14X6 size was what I had in mind if I used that Webra .91. But I don't know what RPMs to expect from it.

With the .65 or .75 size engine, I thought a 13X6 would probably be about as big as could turn and stay in the power band.

daveopam

My Feedback: (9)

The first pic is about 9 years old or so. I can tell by the JR Max6 radio I was using at the time. The 13x6 is just right for a 75. If you go 65 think about 12x6 or 11x8. The gear does look different. If it will keep the wheels from going throught he wing it would be well worth it.

David

captinjohn

youngun: I will try to find the write-up on the .90 Suprtiger. Capt,n

youngun

David,
RE: Did the stock wire gear 'pop out' of the plywood slots that go up the side of the fuselage, on the inside of the fuselage - or did the wire itself bend back, when it went though the wings?

daveopam

My Feedback: (9)

It would go back and up at the same time. If you run wheel pants they would go through the covereing every time. The tires would sometimed just stretch the covering. On a hard hit the wire gear would actually break the leading edge of the wing. Or at least the leading edge sheeting. This is the state my lower wing is in right now. I have patched it twice before. This is the reason I replaced the plane. It got heavier with every repair. These were some pretty hard hits. But then again most dead sticks with an Ult are hard hits.
For everybody reading this: Please don't think I am giving this plane a bad rap. I think everyone should own one of these. It has been one of my favorite planes for 15+ years. Some or most of the hard landing are from my flying style. For example on the last one I did an elevator from 500' up. The plane was dropping straight down at a good clip.At 30' I turned off the spoileron mix and throttle up. The engine stumbled and died. I guess I advanced the throttle to fast. This resulted in a pancake with almost no forward speed. Like I said my fault. However the gear is the weak area of this model. I have two pieces of advice for anyone flying the Ult. One, do not use low rate elev. If the plane dies it is not enough throw to keep the nose up. Second,on any deadstick put the plane down where it is. Do not try and turn it or glide it closer in. It will not snap but you will scrub airspeed quickly.

David

youngun

This is about the kit itself - the issue of missing parts - wood quality - and the kit quality in general;

Right after I received the kit, I tried to 'inventory' the kit then - and found some missing parts then.
(I was using the parts identification list in the front of the manual - not the 'parts list' sheet, which I found later.)

I called Tower and they referred me to "hobby services". And hobby services said, no problem, and that they are sending the parts.

After that, during the building, I kept finding more and more missing parts. First, a missing pushrod, then other things just weren't there. When it was just the pushrod, I was going to just let it go. But as the list started growing, I decided to call hobby services again.

I thought that since I had already called once before - that they might not want to send these.

But, again - no problem - they are sending the items that were missing from the kit.

The problem was Laniers' poor quality and poor quality control (read GREED) which Great Planes is now taking care of.

I hope Great Planes doesn't discontinue any Carl Goldberg products because of all the problems caused by Lanier.

If you are considering buying one of these, Great Planes is standing behind them now and taking care of any shortages - at least when I called them.

Also note that, some items, such as the C.G. pushrod exits shown on the plans, (and not marked with an "NI" ) were not there, and I couldn't find them on the parts list, or any part numbers for them.


About the wood and building;
One of the first things noticed was that the angle of the elevators didn't match the angle of the stab. This is after building them, so the stab was sanded to match the elevators. That could have been corrected and built to match, if it had been known before building.
Dumb me - I thought the plans would be right.

Also the plans aren't the nice "blue" blueprints that Goldberg always had, but now thiner paper "black line" plans. And the manual isn't the nice pamplet book that Goldberg had, but a stack of xeroxed copies stapled together.

Now, I have run into a problem with the slotted trailing edge pieces having the rib slots located different from what the plans show. Is this another place where the plans are wrong, or was the wood cut wrong? The wingspan of the plans is 54" - if built with the supplied slotted trailing edges, the wingspan will be right at 53 1/2". I'm thinking about relocating and re cutting the rib slots in the wood.

I had told David earlier that the wood looked to be of average quality. However, after getting into the kit, I'm finding some good light balsa and a lot of hard heavy balsa. The pieces used to build the tail surfaces were on the hard and heavy side. Most of the 1/16th" wing ribs are of the light variety of balsa. I'm going to try to put the heavier ones on the left side to counteract the side mounted engine weight just a bit.

The lite ply parts - for their weight, they should be made from aircraft grade plywood and not lite ply. At least two sheets have strips of the last layer of wood torn out (and missing), making the parts affected questionable for use.

All these problems that Lanier should have never let happen. Keep in mind that this isn't a "cheap", price wise, kit. For the money, there should be a high quality product - like the old Goldberg kits were.

I never saw, or heard of, these kinds of problems with any of the Carl Goldberg kits in the past - when Carl Goldberg owned and ran the company.
(I built some of his control line kits years ago and an just finished an RC Super Chipmunk kit that I bought years ago when Carl Goldberg owned the company - and friends had others - Falcon 56s and Senior Falcons come to mind. Good kits and good planes all)

I'm hoping that Great Planes will bring back the quality that Goldberg was known for. If they do - I will buy another in the future.

Meanwhile - I've got to try to fix and/or work around all of Laniers shortages, shortcuts and mistakes. I had hoped to have a good flying, light weight, Ultimate from this kit. Now, I don't know. I'm beginning to see how others have turned out so heavy. I guess if it turns out heavy, it can always be hung up as a display model.[&o]

I hated to say anything negative about the kit, since Great Planes now owns Goldberg and they have been good about things. But, I felt that people should be warned about what I got with my Lanierized kit.[]

daveopam

My Feedback: (9)

YG, I have a few of those pushrod exit pieces if you want them. Just PM me with your address.

David

youngun

Thank You David!

PM sent!

daveopam

My Feedback: (9)

They are going out this AM. I thought I had a bunch of new ones. It looks like I have some of each. SORRY. I sent you the six I had. I think you can find four good ones no problem. I also sent both books. I am interested to hear if these books are the same ones you have.

David

youngun

Again - Thank You David![sm=teeth_smile.gif]

I'll be glad to let you know about the books.[sm=thumbup.gif]

Vulturetec

Years ago I flew mine with a Webra .61 and it was fine. The airplane would knife-edge indefinitely, including knife-edge circles, and every normal maneuver in the book - but lacked in "vertical" performance a little. I later put a Super Tigre .90 in it...but the .61 was a good engine for the airplane.

youngun

About the wing construction;

I considered as many options as I could think of about the wing situation.

The problems:

The trailing edges had the rib slots cut in the wrong locations. These would have not only made the wing a little shorter (almost 53 1/2 inch span), but made the center section too wide for the supplied center section braces to work as they should.

The wing plan was the right span - but the right side is longer than the left side, making the "center" off center.

So .... both the plans and the pre-cut trailing edges were not correct. This answered my question about which was wrong - and the answer is BOTH.

My solution: (I'm sure there are other solutions that would work equally as well)

I used a new center reference point on the 54" span wing plans - and working from that point - marked and cut new rib slots in the trailing edges.

I cut all four at the same time so that all four would be identical. This gives not only a 54 inch wing, but a center section that is in the center and that the other parts fit as well.

Interestingly - there were two slots that didn't need to be re-cut. Going out from those two, all the rest had to be moved toward the ends of the trailing edge pieces.

Anyway .... I now have what will be the lower wing started on the building board. (no bellcrank assembly, but with paper tubes through the ribs for servo wires). Things SHOULD go better now. (I'm hoping)


BTW - While building the wing, I couldn't help but notice the airfoil shape of the ribs. The airfoil looks a little different than any other wing I have ever worked with. Could this be one of the reasons for the Ultimates excellent flying reputation? I suspect so, but don't know one way or the other.

On the positive side - the airplane seems to be well thought out and some good engineering went into its design. It appears that with proper wood selection, proper cutting of parts and with correctly copied "blueprints", that this could very well be built into a light, strong, high performance aircraft.

More later ... if anyone is interested.

youngun

THANK YOU !! for your post![sm=teeth_smile.gif]

That is the kind of info I have been looking for.

Your report backs up what others have said.
i.e.: That given my flying style, the .65 should work fine - IF the plane doesn't come out heavy.

Do you happen to remember about what it turned out weighing? Was it a kit from the time that Carl Goldberg owned the company?

I am now concerned about mine coming out heavy due to the heavy wood Lanier supplied in the kit.

daveopam

My Feedback: (9)

Youngun, you can igore my last PM. I see you decided above.

David

Vulturetec

No, I never weighed it. The kit was an original CG one with the plastic cowl and wheel pants - I built it exactly to the plans so it was pretty close to "stock".

Here it is: (sorry for the lousy scan)