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Pumpkin drop event

Alternate foamboard testing

sprzout

Knower of useless information
Mentor
#21
You'll also have to pay attention to the weight. I bought some Wal-Mart Foam board and it's twice as heavy as the Adams rediboard. Chuck glide it first to make sure of the chances of it flying well. Of course you can add more power but that adds more weight. Ask someone who has built the cub how much theirs weighed and compare them.
I think that if you look at the plans, most of them have an AUW (All Up Weight) or Flying Weight to give you an idea of how much it SHOULD weigh. It may not be on ALL of them, or may be listed as something other than AUW (i.e., Weight Without Battery), but it should give you a rough idea.
 

n0ukf

New member
#22
With the ailerons now being reduced in cord you may find that you have inadvertently increased the negative incidence angle of the wing, (it points downwards at the front), and this negates or reduces lift when trying to maintain flight. You may need to place a shim or 2 under the wing LE so that the plane will fly if at all. If necessary you could always extend the ailerons and even the wing tips to obtain greater wing area!
Reduced cord? No, the ailerons were just cut off to reattach with real pinned hinges. This plastic sheeting would never work as a flexible hinge like paper and hot glue does. The wings are fully the same size as the plans show.

The turning or doing donuts could be simply the wheels binding on the axles or a "P" factor issue. A large SF prop will reduce the "P" factor effects and so a straighter taxi will be easier. If it persists you may wish to consider adding some side thrust!
For the wheels, one thing I'll do is (silver) solder washers to the last bend to keep them from trying to ride up the gear. I'll also try making bottle cap and pool noodle wheels instead of foamboard and coffee straw (apparently too-soft bushing). How much thrust difference is there between the 9x4.5 and 10x4.5 props included with power pack B? What about going from 3S to 4S? How much prop and battery can it handle?

Have fun!
That's the point. ;)

Hondo76251 said:
That foam probably isnt ideal for the flitetest build methods but it is pretty strong. Ived used similar before for home made designs that worked well. Might as well figure out how to build with what you got!
The main issue with FT build methods on this foamboard is that you don't want to bend it much without heat softening it first (hot glue or whatever), no test-fit bends. Also (as mentioned above) no flexible hinges, the plastic is too stiff and brittle. Use real pinned hinges instead, or tape or monokote hinges. Where gluing flat surfaces together, you may also want to rough it up like with servo sides to give the glue something more to grab onto.

One case where the increased weight shouldn't be a problem is if using this board to build boats.
 

Hai-Lee

Old and Bold RC PILOT
#23
Reduced cord? No, the ailerons were just cut off to reattach with real pinned hinges. This plastic sheeting would never work as a flexible hinge like paper and hot glue does. The wings are fully the same size as the plans show.


For the wheels, one thing I'll do is (silver) solder washers to the last bend to keep them from trying to ride up the gear. I'll also try making bottle cap and pool noodle wheels instead of foamboard and coffee straw (apparently too-soft bushing). How much thrust difference is there between the 9x4.5 and 10x4.5 props included with power pack B? What about going from 3S to 4S? How much prop and battery can it handle?
If the wings are the same size that is good BUT the simple cub in its original format does not like being too heavy as it has a slight wing incidence angle. If too heavy the front of the wing will need to be raised, (I use a PP stick), so that the wing has a greater incidence angle and therefore provides MORE lift in level flight.

As for the props if the motor on 3S can handle the 10 x 4.5 then use it. DO NOT use the large prop on 4S unless you want to burn something!
When going from 3S to 4S the power goes up by a large percentage for the same prop so to keep the current to reasonable levels the prop sixe is normally reduced. Consult the chart for the motor before changing the battery cell count. (Do so for all planes you have now and in the future - Make it a rule and your motors will last much longer).

Have fun!
 

Tench745

Active member
#24
I have not built or flown the simple cub, so, grain of salt. It looked to me like two things were happening to get your doughnuts. 1) the wheels would hit a tuft of grass on your laneway and slow that side down. 2) The tail would lift slightly, removing some of the friction from the tail skid which helps hold the aircraft straighter. I think, but can't say for certain, that if your cub is balanced it will fly very "scale" with that excess weight. Real cubs don't take off in two airplane-lengths like everyone expects our models to.
 

n0ukf

New member
#25
It may be hard to tell in the video but it was not hitting tufts of grass to make it turn. I think the wheels were trying to ride around the bend and up the wire toward the fuselage, creating rolling friction. I'll (silver) solder washers on the axle bend to prevent that.
 

Tench745

Active member
#26
It may be hard to tell in the video but it was not hitting tufts of grass to make it turn. I think the wheels were trying to ride around the bend and up the wire toward the fuselage, creating rolling friction. I'll (silver) solder washers on the axle bend to prevent that.
Meant to add, I have soldered washers on the LG of many of my planes as you describe. Definitely worth the effort.
 

Hondo76251

Well-known member
#27
I'll also use a small straw as a sleeve inside of the home built foam wheels to keep the wire (axle) from wallowing out the hole and to keep it rolling smoothly.