Marcel: Need some info on Waco

[Don Leitz]

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:

[nimwegen]

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.

[Don Leitz]

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

[nimwegen]

Hi Don,

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

Marcel.

[Don Leitz]

WOW! :eek:
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

[Don Leitz]

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

[nimwegen]

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.

[Don Leitz]

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

[FX1SUB]

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.

[nimwegen]

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.

[Don Leitz]

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

[Don Leitz]

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

[nimwegen]

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.

[Don Leitz]

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

[Don Leitz]

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

[nimwegen]

Hi Don,

I think you are right the BEC must be defective, I think the weather is getting better later this week, I have mine ready to go again too. I am looking forward to seeing yours fly.

Later,

Marcel.

[Don Leitz]

Got two flights with the Waco in today. NO problems with the UBEC. Take-offs from our (mown) field were prompt, but "interesting" until the plane built up some speed. I think I'll try to keep it on the ground a little longer next time. Overall, the plane flies well - good roll rate, decent loops, stall turns and nice inverted. I was surprised at how slowly the plane will fly straight, making landings easy. However, it does snap easily a low speeds using rudder inputs only - most of my planes won't snap as fast with full rudder and elevator inputs as this plane will with rudder alone! I think I will play around with the aileron throws, reducing the down aileron and decreasing the rudder throws a little. Overall, I'm pretty happy with it.

Don

[nimwegen]

Hi Don,

How was the field this Saturday (April 12)? I could not make it, to much stuff to do at home. But I flew my Waco today at the Hawks field in Hamiltucky :) and I made two flights. First one with a 10x5 Master Air prop, second one with a 10x6 APC. With both props the plane took off from the nice runway very quick and no left roll. With the 10x5 it flies fine but not much excess power, I pretty much had to keep the throttle at 80% or more, with the 10x6 power was much better, flies at 60-70% throttle and the plane has nice vertical power. The flight times are still fairly short, about 5 minutes.

Does your Waco roll at the top of a loop. Mine does this and I can prevent it by reducing power, so this is most likely torque related.

Over all I was pleased today with the Waco. I always find it hard to fly when gas planes are also up, mainly because the smaller speed 400 sized electrics don’t compare that well. But the Waco flies at about the same speeds and height as most gas planes do, just a little shorter flight time.

Marcel.

[Don Leitz]

Hi Marcel,
Sorry you couldn't make it Saturday. The weather was nice for a change, and we had a pretty good turnout. I haven't noticed the Waco trying to roll out in loops - does yours always roll to the left? Is it rolling or snapping out? I'll pay more attention next time I fly it and try loops at different speeds to see if mine has that tendancy as well. My Lazy Bee will roll out of a loop if the speed at the top of the loop is too slow because of the pendelum effect of having the batteries located so low in the plane relative to the wing. This shouldn't be a problem with the Waco.

I like the way the plane looks in the air, and other than the rudder being so touchy, it seems to fly well.

I agree that the larger planes have more presence in the air and blend in better at glow fields. I flew my Waco, Accord 47, and Somethin' Extra this weekend and really enjoyed getting the bigger planes out after a winter of flying the smaller hand-launched stuff.

Hope you can make it this Saturday.

Don

[nimwegen]

Hi Don,

What are your flight times with Waco, I keep my timer set to 5min, and with mixed flying it's time to land when it goes off.

Also, how are the take-offs from the grass, any nosing over?

I did not notice the rudder being touchy, do you think this could be CG related? I mix ailerons and rudder and I do have good differential on the ailerons.

Marcel.

[Don Leitz]

My timer is set for 6 minutes and so far I have landed a little (15-30 sec) early. I don't have enough flights yet to evaluate if I can fly any longer than that. The pack is taking in about 1800 ma, and it's rated for 1950 mah, so 6 minutes is probably a prudent time to land. I am only using full throttle for take-offs and loops, otherwise it flies fine at about half-throttle.

I am holding some up-elevator at the start of the take-off roll and haven't noticed any nose-over tendancies; however, I think I need to let off the elevator a little earlier to prolong the roll before the plane rotates.

I have rudder mixed in with the ailerons and that seems to be OK, but rudder alone is touchy. I don't have any aileron differential, either mechanically or programmed in to speak of, but with the rudder mixed in it seems to turn OK. CG may be a but too far back, but the plane doesn't seem to be real pitch sensitive, which is usually the case with a rearward CG. I need to get some more stick time with it or have someone else fly it and give a second opinion.

[nimwegen]

Hi Don,

Man, it was so nice this Saturday, but I could not come, I haven't had any time flying lately. I think you are right about the CG, it might be a little to far back, you might want to try to make the plane a little nose heavy. If you get 6 min flight you surely picked a great motor/gearbox/prop/battery combo. My 2400 packs are only tacking a charge of about 2200 so they are not up to snuff yet. I need to cycle them some more.

Marcel.

[Don Leitz]

Hi Marcel,
Saturday was a very nice day! I think I stayed at the field until after noon. The Waco flew well; however, I was having some problem with the speed control. At first the motor would not start, and then after about 4 minutes in the air the motor stopped suddenly. I was forced to land downwind in some fairly tall grass and the plane flipped over. The only damage was to the rudder and a stripped servo which is now fixed. I took the opportunity to move the pack forward slightly - I'll see if that makes a difference.

I flew my Accord 47 today - after a good landing (at least for me), the gear tore out. I am really liking these 10 cell planes that can ROG, so I think I'll build a Sport-E Stik for my AXI motor and give up on the ARFS:(

I hope this Saturday is as good as the last one!