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Old Mar 09, 2003, 07:56 PM
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West Chester, OH USA
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Marcel: Need some info on Waco

My Waco is ready to fly except for installing the batteries. All up weight is 44 ounces less batteries. I'm thinking of using the new 1950 FAUP cells, as they only weigh 1.4 ounces each and reportably will hold up to 40 amps. That would give me a finished weight of around 60 ounces. My concern is if a pack made from these batteries will be heavy enough to balance the plane. Marcel, can you please describe how you mounted your battery pack and how far forward you had to place it to get the CG right? I probably won't fly this until the weather is nicer, but I would like to get it finished and move on.......
Thanks.

Don

Here's a picture:
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Old Mar 09, 2003, 08:48 PM
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Loveland, OH
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Hi Don,

Great looking Waco, I think mine weights 62oz or so. I have 10 2400 cells, configuration of 2 rows (2cells) deep on top, 3 rows bottom, like this:

OO ==
OOO ==

(front) (side)

The cells are all the the way against the firewall. I also have a separate receiver pack (standard 4 cells 600Mah). But I still needed some lead to balance it, and you should error on the safe side, more nose heavy than tail heavy.

I cut some holes in the firewall and bottom of the plane for cooling, see picture.

I think you definitly want bigger wheels for our field. I hope to fly mine some more this year too!

Marcel.
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Old Mar 09, 2003, 09:30 PM
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West Chester, OH USA
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Thanks for the info Marcel. Now I'm worried that the 1950 cells won't be enough weight for balance if your 2400s are all the way forward. I do probably have another ounce or so in motor/gearbox weight over your plane, and I plan on putting the ESC in the cowl. Even so. I think I'll try to hang some weights on the outside of the plane to simulate the pack position and see if it will be enough before I order the cells. The wheels that are on the plane now are 2.5 inch, but I have some 2.75 inch wheels on order - plenty of clearance for the 12 inch prop.

Don
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Old Mar 10, 2003, 11:26 AM
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Hi Don,

There was someone else who actually arranged all the cells around the motor, see picture.

Marcel.
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Old Mar 10, 2003, 06:38 PM
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West Chester, OH USA
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WOW!
I hope I don't have to go to that extreme to get the plane to balance! CG correct or not, that looks like a nose-over waiting to happen - and dangerous too with the cells uncovered! I tried to add some weight to the plane on top of the fuse last evening to see how much it will take to make it balance on my CG machine @ 20mm from the leading edge of the lower wing. Actually, I had the plane balanced on the top wing, as that's a lot easier to check. Do you know where your CG is in relation to the top wing?

Surprisingly, it looks like the 1950 cells will work, as 6 2000NiMH cells just in back of the fire wall made it balance - about 9.6 ounces. The way the plane is made. there isn't a lot of room to move the cells between the CG point and the firewall, but I hope that I lucked out and won't have to add any weight.

Don
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Old Mar 24, 2003, 07:10 PM
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CG?

Marcel,
If you get a chance, can you tell me what your Cg is in relation to the top wing? Checking the CG from a position in front of the bottom wing seems to be difficult. Will you be flying the Waco this Saturday?

Don
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Old Mar 24, 2003, 08:36 PM
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Loveland, OH
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Hi Don,

CG is at 3 1/8" from the leading edge of the top wing. If I have time toget mine ready (I need to replace the receiver battery) I will bring it for ROG Saturday. Is yours almost ready?

Later,

Marcel.
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Old Mar 25, 2003, 08:08 AM
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Thanks Marcel. I doubt that I will be bringing my Waco Saturday. I plan on bringing my LT-25, Accord 47, and a smaller plane - either my Flik or Three-Dee. I want to get some more taildragger time in before I attempt the Waco. Hope the weather is good.

Don
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Old Mar 28, 2003, 07:10 PM
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FX1SUB's Avatar
NJ
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Some more details

Hey guys how bout some more details? motor, gearbox, servos, esc and rx placement of each for best balance....I just saw this plane in one of the catalogs I got and for $149 it looks like a great deal.
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Old Mar 28, 2003, 10:27 PM
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Loveland, OH
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FX1SUB,

There is a lot of info on a thread Don Leitz started uder scale models on the ezone, but here some info on mine. I fly mine on a mega 22/30/3, 10x5 prop, 10 2400 cells. The receiver sits on the lower wing, servo's just behind the lower wing. It's a good flying plane, but not for the faint of heart. I have made maybe 10 good flights now, it still makes be a little nervous. The Waco flies rather fast and will want to tipp stall on take off. Several people that have build one (as reported on the ezone) have crashed theirs by now. I still am happy with mine.

Marcel.
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Old Mar 29, 2003, 02:27 PM
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Mine is now ready to go. Since I didn't go to the GCRCC field this morning, I took the opportunity to finish up a few details. All-up weight with the 1950 cells is 59.7 ounces. I am using an Endoplasma instead of the Atomic Force motor that I had originally planned on, as it will provide a little more power and is already broken-in. It's geared 4.5:1 and drives a 12x8 prop, so thrust should be good - Motocalc says 63 ounces. Pitch speed is 58mph - hope that's enough!

My battery pack is built in 5 sticks of 2 end-to-end cells, 3 sticks on top and two on the bottom. This is velcroed to a ply plate which is glued to the internal ply longerons and cross plates below the cabanes. With the cg @ 3 1/8", the pack sits about 1/2" behind the firewall, so balance wasn't a problem.

Now all I need is some more taildragger time, a range check and some good weather!

Don
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Old Mar 29, 2003, 06:39 PM
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It flies!

Well, the wind died down a little and the clouds parted, so I took the Waco to the field and did a range check. Everything looked good, so I decided to see how it would fly. The take-off roll was surprisingly short - about 20 feet. Immediately after rotation, the plane started to roll left a little. Some right aileron took care of that and the plane climbed out strongly. After leveling out, a couple of turns revealed that it turns like a bipe, needing lots of rudder. Then the motor stopped abruptly, forcing me to land deadstick. No problem, as the plane glides pretty well, but a little fast. I kept the speed up and made a shallow turn into the wind and the plane landed with a little flare just before touching down. All would have been well except that the wheels must of hit a divit, as the plane stopped and nosed over. Thankfully there was no damage.

I checked everything out and couldn't find any problems, so I decided to try it again. Another short take-off roll and a few circuits later, the motor cut again. This time I was forced to land downwind and made a near-perfect landing, although it was a little fast. No nose-over this time. I obviously have a problem somewhere. It may be that the batteries need a couple of cycles before they are working strongly, or maybe somethng is wrong with the speed controller, although it did work OK in a previous plane. I don't think it was a radio glitch, as the plane remained in control at all times.

Anyway, if I can find the motor problem, I think I am going to enjoy this plane - it's not nearly as difficult to fly as I had thought it would be.

Don
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Old Mar 30, 2003, 10:15 AM
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Loveland, OH
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Hi Don,

That is great, two successfull flights!!!! Where are you flying? Are you taking off from grass or pavement?

THe motor combo you have should be really good for this plane.

Pitch speed Endo (12x8): 59mph, thrust 61oz, power: 391W
Pitch speed Mega (10x5):53mph, thrust 50.8oz, power:341W

You Waco also has the weight advantage, I think mine is about 68oz, yours only 60oz.

In flight you still draw 32A or so, my motor draws less than 18A or so. Do you think the batteries you are using can handle the current draw?

Marcel.
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Old Mar 30, 2003, 08:21 PM
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Marcel, I am sure that your setup is more efficient in the air - I just wanted to make sure that I could get it off the ground. I will probably prop down to a 11x7 if the plane feels like it would fly well on less thrust. I bet it will fly fine @ half-throttle the way it's propped now. I'll be happy if I get 6 minute flights. The batteries are reported to be able to handle 40 amps with no problem.

The flights were made from the grass soccer fields in the middle of the park, as they were empty and are fairly smooth. I much prefer taking off of grass to pavement with a taildragger.

I did a little troubleshooting this afternoon. It appears that the ESC cuts out when I move the ailerons rapidly. I disconnected the control linkages and the ESC still cut out. Next, I disconnected one aileron servo - no cut out. Then switched to only the other one to check for a bad servo - again no cut out. So my guess at this point is that I am overloading the BEC on the ESC, even though it is rated for 2amps with 12 cells. I'll try a receiver pack to see if that works with both servos hooked up. If it does, I'll either install a UBEC or get another ESC. I like this ESC (Kontronic Sun 4000), but maybe something is wrong with it.

Don
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Old Mar 31, 2003, 06:52 PM
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Problem Solved (I Hope!)

I did a little more troubleshooting this evening. No motor cut-out with a seperate receiver pack, so I think the BEC was either overloaded or defective. I thought about buying another ESC, but as I had a UBEC waiting to be installed in another plane, I thought I would give that a go. Seems to work fine, although it was dark when I finished, so I still have to do a range check. The plane gained 0.7 ounces, but that's still less than if I had installed a receiver pack. It should be OK now, but the proof of course will be when I fly it.

Don
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