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Old Dec 19, 2011, 04:45 AM
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Maxa E -


A plywood box was waiting for me when I got home last night. Inside was a Vlad's Models Maxa, otherwise known as Joe Wurt's new Toy.

Don Harban has one already and has posted some preliminary info: https://www.rcgroups.com/forums/show...&postcount=149


Weights:
Left tip with joiner 232 g
Right tip with joiner 228
Centre panel 608
Elevator 32
Tail Boom/Rudder 108
Pod + canopy about 1444

This one is wing number 43, so early build. Electric pods will be even scarcer on the ground.

Its a gorgeous model and should fly well. As others have noted on the F3J forum its airfoil is certainly fatter at the front than that on the Supra.

Empty air frame 1353 grams or about 47.5 oz

Don has already pointed out that the E pod has an immediate problem, in that there is next to no space. Part of the problem (in my view) is the hatch cutout is too small to allow room to install the servos further back. It may be that a new hatch is required.

The attached photo shows a Neu 1105 2.5Y with a 3S 1100 battery. That combo with a slightly heavy Hacker ESC weighs around 250 grams. It should be just enough power, around 400-500 watts or a bit over 100 watts/lb in the old school. I prefer 200 watts lb but this will be strictly an electric assist thermal glider.

Adding in 180 grams for six servos, a receiver, receiver battery and a small regulator, projected in the air weight with this setup is somewhere around 1900 grams.

The wing build looks very straight forward. The power pod /elevator servo bits anything but.
Last edited by davidleitch; Dec 19, 2011 at 06:43 AM.
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Old Dec 19, 2011, 06:02 AM
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Reserved for flight commentary


....
Old Dec 19, 2011, 06:08 AM
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After resoldering the esc so the wires were as close as possible to the motor, its clear that the fit is going to be a nightmare. Getting a Blaster 3 going was child's play in comparison.

Also I bought a glider fuselage just in case the electric version had issues, and to no one's surprise the E- pod is just the glider pod with the nose cut off and a motor mount installed. My bet is that a separate E nose cone that is a bit larger will eventually be produced, but I might be wrong.

Unlike Dons my E Pod ballast tube came separately.

The bell crank on the elevator means that its impractical to install the rudder/elevator servos in the tail.

Having whinged its appropriate to note my building skills and imagination are limited so a better builder may do it more easily.
Old Dec 19, 2011, 06:18 AM
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Vlad's suggestions


Vlad's suggestion is to put the servos underneath the wing. I'm going to have a closer look at that although certainly there isn't much space there either.
Old Dec 19, 2011, 06:37 AM
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Last one for tonight. In this photo the ESC is under the servo tray, the receiver and the 3S 1100 battery are further down the pod. I guess in the real world they will be on a tongue. Removing the battery will require unhooking the servo clevis.

Other than my park flyer every other plane I have has a separate receiver battery. I guess that can go on the tongue as well, further back.

Well a night's sleep will hopefully make things clearer.
Old Dec 19, 2011, 07:47 AM
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Originally Posted by davidleitch View Post
Vlad's suggestion is to put the servos underneath the wing. I'm going to have a closer look at that although certainly there isn't much space there either.
David,

It is just as well that the ballast tube has not been installed in yours. I have concluded that I will be grinding mine out. But I think I have come up with a good solution (although not cheap) for installing ballast. A 12" long x 7/16" diameter tungsten bar weighs about 10 ounces. I think I will fabricate a piece to install in the back of the pod which will center the rod, fashion a point (dull) on the end of the rod and fabricate a piece to attach to the front of the rod which will be essentially flat for 4" or so and then transition to the rod shape. with the battery removed you will guide the rod down into the fuselage and into the rear guide. You will then fasten it with a ballast screw just like the stock ballast rod -- but without the tube. The flat transition piece at the front of the rod will give you plenty of space to insert a Thunderpower 3S 1300 65C on top of your esc -- all aft of the back edge of the canopy opening. You could accommodate different ballast weights by varying the length and diameter of the various rods.

As I discussed elsewhere, I am inclined to install the motor, followed by the servos, followed by the ESC and Battery (together) , followed by the receiver and BEC as you go from front to back. I do not like the idea of setting the ESC (and its attendant wires) on top of the servos as shown in Vlad's third drawing on the off chance that, in the course of tucking everything in and snapping the canopy on that something stray will interfere with the servo horns and cause a fatal bind.

Today's task is to determine whether my gear choices will balance the plane without any extra weight.

Happy Landings,

Don
Old Dec 19, 2011, 09:08 AM
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I have attached a rough (not quite to scale) sketch of the layout I am looking at. Everything appears to fit -- at least to the extent that I can determine before I take the ballast tube out. We'll see.

Happy Landings

Don
Old Dec 19, 2011, 11:30 AM
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Well I got my morning finished. I put the assembled model on a balance stand set up so the plane balanced at 100 mm behind the leading edge. I then hung a weight on the nose (see attachment) to determine the distance from the CG and hence the balancing moment that would be required once the equipment was installed to bring the plane into proper balance.

Then I set up a spreadsheet and entered the weights and approximate distances from the CG for them. It turns out that the 1107 setup that I was contemplating would take about 1/2 ounce of weight in the tail (probably more once the installation is complete. The 1105 is almost spot on with a 1300 3S and would require a bit of nose weight for the 850 3S battery.

I think as a starting point, I will try the 1105/1300S combination just to see what happens. It seems a bit low on power to suit my style, but part of the reason for this drill is to see how a plane weighing what its TD mate does will perform.

Happy Landings,

Don
Old Dec 19, 2011, 02:36 PM
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Did yours come with the receiver end wiring harness? Mine did not which will require trial and error soldering of the micro deans plug to determine wher the positive and negative pins are.
Old Dec 19, 2011, 02:58 PM
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Did yours come with the receiver end wiring harness? Mine did not which will require trial and error soldering of the micro deans plug to determine wher the positive and negative pins are.
Yes, I received the harness. If you need help on arranging the wiring, please let me know.

In addition I got the ballast tube out of the way and, at least with a mockup battery pack, the arrangement I described above seems to be very easy to arrange and very workable. I am going to space things so that I can switch to the 1107 if I want more power.

I have to say, it looks much more troublesome than it really is -- if we end up with enough power.

Happy Landings,

Don
Old Dec 19, 2011, 04:39 PM
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Yes, I received the harness. If you need help on arranging the wiring, please let me know.

SNIP
Happy Landings,

Don
If you were able to say which pins have the + and - on the wing connectors that would be helpful.
Old Dec 19, 2011, 05:52 PM
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If you were able to say which pins have the + and - on the wing connectors that would be helpful.
The Deans plug has one pin (the polarizing pin) separate from the other three.

The polarizing pin is the Negative pin. The one adjacent to it is the Positive pin. And the remaining two pins are the signal pins for the respective two channels.

Happy Landings,

Don
Old Dec 19, 2011, 05:59 PM
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Thanks Don,
I also took an earlier suggestion of yours about something for the wife for xmas on board as well. A good thought.
Old Dec 19, 2011, 06:03 PM
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post more pictures guys! Looks like an interesting project, to build a TD composite ship that just happens to have a small motor.
I have these fantasies (dreams?) about buying a TD ship off FS/W, like a Sharon 4.2 m, then putting a small motor in it, keeping the weight the same..
Old Dec 20, 2011, 03:26 AM
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Now have a few days off before Xmas, so hopefully a bit of time to mess with the Maxa.

Putting the ESC on top of the servos will clearly work with the small Neu Motor and the 1100 3S pack. Putting the ESC on top gets rid of any binding issues.

There even appears to be room for a Hacker B40 6L motor if there was a need.

This layout would allow the battery to be removed.

The other photos compare the centre panel of the Maxa with that of the Supra, leaving aside the 'foil difference they are similar, a touch more chord on the Maxa. Having a similar size centre panel is handy for transport. It means the Maxa can go in a Supra sized soft bag. The bags are great for your models.

However when we compare the tips the Maxa is considerably larger.

Even though I think I have the motor layout sorted I am going to consult a much better builder than myself, Graham Allen, and see what he thinks. In the meantime I'll work on the wings.


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