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Tested my Cedar Hobbies Twin Stick

Old 06-12-2005, 12:50 PM
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Ed_Moorman
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Default Tested my Cedar Hobbies Twin Stick

I test flew my Cedar Hobbies Twin Stick today. Put 3 flights on it.

The plane came out very nose heavy. I ended up placing a 5-cell, 1650 NiMH pack where the fuselage servos normally go and installing the servos in the rear fuselage just forward of the empenage. I even used a 3rd servo back there, a standard Hitech 425BB, for tail wheel steering. The other 2 servos were Hitech 5625 digital metal gear servo so they were heavier than standards. This weight in the rear, plus a heavier, after market, tail wheel assembly, finally got the CG back to the main spar. I hate adding lead, hence the servo move.

Power is 2 GMS .47 engines with APC 11-5 props. Each has 8 degrees or so of out thrust. I also side mounted since the indicated, upright mount would have placed the carb much higher than the center of the tank.

Final, all up weight on empty tanks is just under 8 1/2 lbs. This is higher than I expected, but that's what it is.
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Old 06-12-2005, 01:03 PM
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Default RE: Tested my Cedar Hobbies Twin Stick

Tropical storm Arlene passed through the Florida panhandle yesterday so today was nice and clear with hardly any wind, just right for a test flight.

Take off was good. It is pretty short coupled so it can want to zig-zag on take off. You need to take it easy on the power application. The first flight I trimmed and generally felt it out. I tried a high landing pattern to check stall characteristics and on low rate elevator it wouldn't stell. On high rate is finally gave a little stall at full back stick. I may need the CG back some more. I may have to cut a hatch and move the battery further back.

Back on the ground, I checked all the joints and engines and everything was OK. A few cranks of fuel and I was ready to go again.

This time I tried a little acro, not a full work out. Everything felt good during the whole flight so I was surprised on final approach when I noticed one engine out. I don't know when it failed so the out thrust is working.
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Old 06-12-2005, 01:17 PM
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Default RE: Tested my Cedar Hobbies Twin Stick

On the third flight I pulled her up to vertical after take off. Oh, yeah, it does have some climb. Love the climb. It's also surprisingly fast in level flight.

Insides and outsides are good. Down elevator is more sensitive than up, but this is to be expected from a plane with a low mounted stab. Knife edge requires a lot of aileron and elevator correction. Inverted is easy. 4-point rolls are excellent. Cuban-8s are very nice. Snaps are so-so, probably because it doesn't stall very easily. Something to work on.

Overall: excellent flying plane. Love the climb. I think I'll be flying it a lot.

See you guys at the McDonough, GA, twin meet on the 25-26th of this month.
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Old 06-12-2005, 02:15 PM
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William Robison
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Default RE: Tested my Cedar Hobbies Twin Stick

Ed:

Glad it went well, and that you're pleased with the plane.

Mine isn't getting bashed as much as I had originally planned; it will still be a high wing but I'm putting anhedral in it. Should help eliminate some of the coupling in KE flight.

And as I said before, a pair of LIGHT K&B 8330 engines. High torque, fairly low rpm. The two K&Bs together don't weight much more than one of your GMS 47 engines.

And, no out thrust. I've figured out why I don't like it:

...so I was surprised on final approach when I noticed one engine out. I don't know when it failed so the out thrust is working.
If we let it be known that flying a twin can be so easy the comment "You fly twins? Gee!" will become "So you fly twins. So what?" See what I mean? Takes the mystique out of it.

Haw.

Again, glad it worked out. Hope I wont have the balance problem, and end up a lot lighter.

Bill.
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Old 06-12-2005, 02:20 PM
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Default RE: Tested my Cedar Hobbies Twin Stick

Mine has no out thrust at all, and it is still hard to tell if an engine has quit. I have lost both engines at one time, or another and you can just bearly tell one is out. Mostly by sound. You can turn into either dead engine with no issues.
I would guess this has to do with the fact, that the engine thrust lines are so close to the fuse centerline.
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Old 06-12-2005, 02:24 PM
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William Robison
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Default RE: Tested my Cedar Hobbies Twin Stick

Terry:

How did you come out on balance?

Bill.
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Old 06-12-2005, 04:35 PM
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Default RE: Tested my Cedar Hobbies Twin Stick

You guys are killin' me.. damnit....


Here I had the original little stick plane going and now you all have 'em.. <sniff / sniff>
And mines all brokey... boo/hoo ..........

least MINE is a white one... naa naa naa..

Ed, glad it is working out and you are havin' a blast with it...

Look forward to seein' it....
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Old 06-12-2005, 06:09 PM
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Default RE: Tested my Cedar Hobbies Twin Stick


ORIGINAL: William Robison

Terry:

How did you come out on balance?

Bill.
Mag XL .40s, micro servos for throttle, battery at rear of radio compartment, 2 servos in tail, & 5oz lead on the bottom of the stab.
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Old 06-12-2005, 09:53 PM
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Default RE: Tested my Cedar Hobbies Twin Stick

Ed, By the size of your smile in the photo, I'd say you were pretty well pleased! Nice to know you can lose a motor and not even notice!


Dan[8D]
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Old 06-14-2005, 02:18 PM
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Default RE: Tested my Cedar Hobbies Twin Stick

Terry,

I am trying not to add lead to mine, so I am moving my 5-cell, 1650 mil battery back. I have removed a section of the bottom of the fuselage and glued in a floor to make a battery compartment. As soon as I get home, I'll do a little sanding and hook up the battery and screw the hatch in place.

I am trying to keep all my batteries readily removable since I am going to Robby's Multis Over McDonough meet on the 25th-26th. It's a lot easier to take the batteries into the motel room to charge them than carrying fuselages. I hope to meet some of you guys there.
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Old 06-19-2005, 02:54 PM
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Default RE: Tested my Cedar Hobbies Twin Stick

william robinson,
trying to find the k&b 8330 engines you mentioned and these are the models i found
Model
Size Bore Stroke H.P. RPM Weight Prop
4011 0.40 0.84 0.72 1 2,600-13,000 13.5 oz 10X6
4050 0.40 0.84 0.72 1.8 2,200-18,500 15.4 oz 10X6
4060 0.40 0.84 0.72 1.4 2,200-14,500 14.9 oz 10X6
i have the 4011 could you show the specs of the 8330
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Old 06-19-2005, 03:26 PM
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Default RE: Tested my Cedar Hobbies Twin Stick

captjack:

The 83xx engines are out of production, to get any you'll have to buy from a private party. They all had the smaller front bearing, very similar to the series 61 K&Bs.

The 8330 was the earlier 40 RC engine, it had a small bore Perry carb, good torque but not a lot of rpm.

The 8350 had an enlarged front housing with the carb mounting spigot much larger than the 8330, and a correspondingly larger bore carb, still Perry, when it came out it was about the hottest 40 on the market.

The 8360 was also known as the "Q-40" engine. It had a monster sized Perry carb, and a Perry pump built into the back plate.

Telling the 8330 from the 8350 is easy if you have both in your hands, but looking first at one and late the other can be difficult. Roughly, looking at the front housing and the carb mounting spigot, if the outside of the spigot is about 1/2 the size of the nose of the front case it's the 8330. The 8350 (and 8360) have the spigot just a hair smaller outside than the nose. The later spigot is the same size as the 40xx engines, so if you compare a 4011 and an 83xx you can see the size. If the 83xx is smaller, it's most likely the 8330. Same size, then the 8350 version.

Pictures:

First has the 8330 in the left rear, 8350 left front. On the right is a pair of 8360s.
Second has the 8360 on the left and 8350 on the right. Difference in the carb sizes is easily seen.

Bill.
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Old 06-19-2005, 07:27 PM
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Default RE: Tested my Cedar Hobbies Twin Stick

captjack:

I forgot about this picture. It shows the 8330 and 8350 difference much more plainly.

The 8350 is on the left, with its carb the lower center. 8330 on the right, and obviously its carb in the upper center.

Bill.
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