Try testing the thickness of the plastic blades. This year, for the first time, we have discovered variations in the thickness ranging between .007” and .010”. It appears that the plastic stock is not being kept consistent as each different thickness material is that thickness over the entire blade.
The best way to determine best is to fly them.
Sorry, missed the dynamic balance question. Very even pitch between the two blades, combined with perfect static balance and perfectly straight shaft will improve the let down duration. This is a very fine adjustment, of course and not nearly as important as matching propeller to rubber, having a very good propeller and winding correctly. I would gues that having a perfectly balanced propeller (dynamically and static) might be worth 5 seconds.
coachchuckaahs wrote:I'll take a stab at a few of your questions.
We don't build from a kit, and our wing and tail posts are same size. Perhaps in the kit the tail posts are smaller because they are shorter, so less bending loads? We use 1/16" square bass wood for all posts on our design.
Not sure on your turning question. Are you saying the nose points inward? Or the inboard wing tilts inward?
We have about a 2.5-3 degree angle on our prop hanger. Other designs will offset the wing posts such that the entire motor stick is angled inward, so that the bearing is in line with the rubber. Tail tilt, tail angular offset (rudder), and prop offset all affect the circle at different portions of the flight. Most designs have some implementation of left thrust for higher torque portion of flight.
Always wind off the plane! If you are properly stretch winding, the wind operation puts a significant load on the hook. The rubber is most likely to break during winding, as it is under stretch as well as wound to a higher torque than launch torque. If the rubber breaks while stretched on the plane you will often do damage to the plane. Further, if using a torque meter while winding, you wind on the torque meter. No easy way to do that on the plane, unless you have an expensive combined torque meter and winder. Damage is the primary reason, torque winding is second but still important.
I think your last question has two parts. Spend as little time wound. This is because the rubber will continue to relax, so if it stays on the plane wound for several minutes, the launch torque may not be the same as you intended/measured. You don't have time to wait anyway, at least in competition. Practice like you compete, for consistency. Second part, winding slowly. I have seen some say that you can "wind too fast", and in doing so may not get as many winds in the motor (again, it is relaxing as it gets stretched in winding). That said, we have a 10:1 winder, and we wind pretty fast. We can put on several thousand winds and then unwind, hook it up, and launch in the 3 minute setup window. If you have a 15:1 or 20:1 winder, perhaps you want to slow it a little. Try an experiment, see if you get more winds (or better time) with faster or slower winding. I am guessing on the scale of SO flying it is in the noise.
“Tilting inward” while circling is referred to as banking. Banking is ok, and even desireable for low ceiling sites, if it accomplishes a reduced climb rate during the early high torque portion of the flight. Knowing how much to bank and whether the bank is effective can be determined by testing. Try adjusting trim settings (rudder, stab tilt, left wing washin, etc.) moreand then less to see what works best.
Nothing is inherently bad about using rudder, various stab post length or thrustline offset. All of these are trim methods used by top level flyers. The most commonly used trim method is to use a moderate amount of all of these: wing offset, thrustline offset, left wing washin, stab tilt, tailboom offset and possibly rudder offset. Different designs and different flying conditions may require more or less of each trim setting for longest duration flights.
It is a little unusual that this year’s FF kit has stab posts above the tailboom. I suspect that this configuration may help reduce Dutch Roll that is the typically occurs in tandem airplanes; maybe. Usually stabilizer posts are below the tailboom serving the dual purpose of making stabilizer incidence adjustable and causing vertical separation of the wing and stabilizer. Increased vertical separation of the wing and stabilizer moves the stabilizer out of the turbulent air caused by the wing (the wing’s wake). I’m not recommending posts below the tailboom though as I suspect the FF configuration may help the tandem stability (also may help prevent the stab from getting bumped out of alignment on landings).
Good luck and good questions,
klastyioer wrote:idk why ppl say that rudder offsets, changing the stab posts, and degree in the bearing is bad i just dont get that.
Rossyspsce wrote:anyone have suggestions on where to start with broad flaring ikara props? I started testing with them last week, and it seems it would be good, except the weight and the fact it can't climb as high due to the weight. I have heard of sanding, just not sure where to start. don't want to completely mess up the prop.
CrayolaCrayon wrote:Rossyspsce wrote:anyone have suggestions on where to start with broad flaring ikara props? I started testing with them last week, and it seems it would be good, except the weight and the fact it can't climb as high due to the weight. I have heard of sanding, just not sure where to start. don't want to completely mess up the prop.
A good start is just cutting and sanding off the junk behind the spar (that allows those props to actually flare). It also reduces weight. Flaring props are more efficient under low ceiling heights, which will be the majority of competition venues.
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