Sherman

I have the Calmato Sport 40 and it is a wonderful plane. Is the sport 60 available yet and does anyone out there have one?

thibor

Yes, my friend bought one last week. Yesterday we started the assembly. The wing is joined, we did reinforce servo mounting blocks with epoxy and had to enlarge the holes for the servo horns, to achieve full throw.

Overall the plane looks verry good. It will be powered by an OS .61 FX.

We'll keep you posted as we go one.

Greats,
Patrick and Philip

wswanepoel

Hi

I hope someone can shed some light on this. I have just finished a Calmato 60 with its own supplied 61 engine. I Fitted a Futaba radio with standard servos and put the battery and receiver as far as possible to the front. It is still so tail-heavy that I need to add 150 gram to the front of the engine to get the CG right. This looks like a design fault to me. What is your opinion Please?

Regards

Bill

bigedmustafa

My Feedback: (2)

The Calmato Sport, like the Goldberg Tiger, achieves its flying stability in no small part to its longer tail length. Like a pattern plane, the Calmato's long tail helps it track straight and true while in the air.

Coming out tail heavy shouldn't be all that unexpected, although you'd hope that using the recommended Kyosho engine wouldn't make balancing it such a chore.

My first step would be to upgrade the receiver battery to something beefier, at least your added weight will allow you longer flying times between recharges. It seems a shame to consider switching out engines since your current engine came with the ARF. Perhaps an aluminum spinner and nose weight could help?

wswanepoel

I have put a 4000 ma receiver battery as far to the front as possible, I have now as well change the engine to an 91 OS (For the extra weight) a big 3 inch alu spinner, and I am still a few grams short.

da Rock

What I'd suggest first is to get a dependable idea of where the CG should be. Don't depend on the ARF mfg's little booklet. Get out a yardstick and make a few measurements and have an extremely good, dependable computation from proven aerodynamic design formulas in about 30 seconds.

See the picture of my 40size Calmato Sport. She's been used a bunch since that picture was taken, but that's the picture I made many flights ago when new. It was painted to illustrate the CG problem with that model from the ARF mfg.

The blue line shows the CG range that was suggested. That's not the CG point, but the entire range suggested, front to back. Pretty narrow, right. The green arrows show where the Neutral Point is on that airplane. The NP is an important bit of info to know. It's where the pitch forces all balance out. It's also very accurately found. The aero forces that apply to this problem are also easily worked out if you've got a yardstick. The size of the wing and it's shape, and the size of the horizontal tail and it's shape and distance back from the wing are about all you need to know. Then plug the measurements into the formulas. They'll spit out exactly where the NP should be.

The green arrows show where the NP is on the 40size Calmato Sport. Going to be the same for all that measure what mine did. All will. The green arrow at the fuselage with the "3." next to it is where the NP is near the fuselage.

And tell the formulas one other bit of info and they'll also tell you where you should try the first CG.

That light blue arrow with the #4 next to it is where I started flying that airplane. The first flight had the CG right there, about an inch back from the mfg's suggested range. I've since moved it a bit more aft. How does it fly? One of the guys I'm teaching to fly is coming along very nicely. The other day, after a couple of good flights on his airplane, I wanted him to see the difference in feel between different airplanes so I handed him the TX while I was flying old yaller there. He liked the way it flew. Stable? You betcha.

So how do you get all the magic numbers with just a yardstick? Geistware.com And they ain't magic numbers. But they're dependable. Go to:

http://www.geistware.com/rcmodeling/cg_super_calc.htm

and look at the measurements they want you to plug into that light purple box. It's the first box at the top of a bunch of other boxes. Plug in about 7 measurements and one choice and hit the button. The other boxes fill in instantly. Look down in the "Calculated Results" boxes for the NP and the CG locations. Pretty easy wasn't it. And a thousand percent more dependable information than we've usually gotten from our ARF mfg's booklets. They build some really nice, beautiful models. Really nice and better than most of us would do. But they very often build in a few flaws. And very often have no clue about some of the more important details they'd have spotted had they flown them. It's up to us modelers to insure our stuff is safe, and better yet, flies ok.

da Rock

There is a fair chance that the CG suggested by Kyosho is way too far forward. Read through my post just above that shows where Kyosho screwed up on the 40size CG.

I'm not sure what engine you changed out, but the OS91 is the same weight as the OS61. A number of the larger displacement engines are made to the same measurements as smaller ones so they can be easily retrofitted in models that were designed for the smaller displacement engines. I'm flying 91s in a couple of my models that started life with OS61s and the models didn't change weight or balance with the retrofits.

A few grams won't be significant. Especially if Kyosho blew it on their CG recommendation as badly as they did for the 40 size.

wswanepoel

To be honest if that is the case, then they have also screwed up the wheel mounting position as well. At this stage I have to fit a tail wheel as the nose wheel does not touch the ground. If I add enough weight to get the CG in the center of there manufacturers range, then the nose wheel does come down, but just. Ok granted the nose will be kept down when the tank is full. I am flying RC planes for the past 30 years and have never had this before. Normally you can get to the CG by moving the equipment around a bit or by using bigger receiver batteries. At the most ad a bit of dead weight, but this much I have never had before. It just shows you are never too old to learn. You are correct about the weight difference between the 91 and 61. That is not much. Anyway I have it now where it is within range, and I will try it out tomorrow morning weather permitting. If it fly well then I will bend the back landing gear to move the back wheels about 25 mm back if necessary.

Anyway thanks to all for the suggestions.

Regs

Bill

wswanepoel

Ok Report back time:

I had 5 flights this morning. It is flying like a dream. The 91 is performing very well in this combination. The only problem is tat the nose wheel is very light, especially after flight with an empty tank. I will bend the back landing gear to position the wheels about 20 to 25 mm backwards. That should resolve the problem.

Regards

Bill

Remember: Nose heavy planes flies like a dog. Tail-heavy planes only fly once.

da Rock

Oh Jeez, I forgot something about my 40 CalmatoSport that I had to correct. When I pulled the main gear struts out of the package when assembling the thing, I couldn't believe it. They had NO rearward bend. The landing gear blocks were directly under where the CG should probably be. So the gear should have angled back from the blocks. They projected straight down from the CG location. They made a perfect CG balancing tool. And really stupid landing gear. Stupid? Yes. Some mistakes are stupid mistakes. And there is no way in hell any tricycle gear airplane is going to work with the main wheels directly under the CG. I didn't even test fit those worthless things into the blocks. Immediately pulled out some piano wire stock and bent some new ones. I could have chucked those things up in the vice and twisted an angle in them, but knew they would never be as trouble free as struts that were bent true to begin with.

I CANNOT believe they are still doing that!!!

It's accepted and known far and wide. Main gear blocks are usually placed slightly aft of where the CG would be. Andy Lennon shows 4-6% of the chord back of the CG. AND THEN the struts are angled back about 20degrees. None of that was done with my 40 size ARF. It proved to me that those people really don't fly what they manufacture.

It really sounds like those people have done the same stupid thing with the 60size.

wswanepoel

You are right. That is exactly the case on the 60 as well. I will bend them and that should solve that problem.