I have finished my chrysalis 2 eletric
amd the weight with the brushless/2 cell lipo and
everything else loaded and ready is 41 oz. (A little
more than it is supposed to be but I think I am OK.
(Wing is 14 oz. and fuse fully loaded is 1 lb. & 11.3
oz.)
From : Don Stackhouse
That's about four ounces heavier than mine, and about six more than Joe's (he's using a different motor with a smaller prop, and no separate radio battery). Mine weighs 37.3 ounces ready-to-fly. The fuselage+tail assembly is 25.4 ounces (1 lb 9.4 oz), and the wing (no carbon added to the spars, but that would add less than an ounce) weighs 11.9 ounces, including the spoiler servos and covering, plus some old repairs.
So, compared to mine, two of your extra ounces reside in the fuselage, and four in the wing. Since you didn't have any problems getting the C/G correct, odds are the ones in the fuselage are not all in the tail, but rather are more forward for the most part. Some of your extra two fuselage ounces will be from the mounting plates for the bolt-on wing option, which I don't have in my prototype.
In most cases, extra weight tends to come from too much glue, and/or cases where someone decided that they don't think the original designer made something strong enough, so they take it on themselves to add some beef-ups of their own. In most cases involving well-designed models these are at best unnecessary extra weight, and at worst (in at least some cases I'm aware of) they actually weaken the model.
In any case, yes, you have some extra weight, and yes it will hurt your thermalling ability a little, but it will not be a significant problem. With a 7-cell RC2000 nicad pack mine weighs 47.7 ounces. With that setup, there is a definite decrease in light-air thermalling ability, but its thermalling ability is still very respectable. Of course the penetration at that weight is awesome! It actually climbs better with that setup, but that's because of the higher current capabilities of the big nicads in comparison to the Li-poly cells, which results in 32 amps and 240 watts, instead of 28 amps and 180 watts in the case of my Li-poly batteries. In your case, you will probably see some decrease in climb, but it will still be quite fast. You might find it can only sustain a climb angle of 40 or 50 degrees instead of 70-80, but that should still get you to altitude very quickly.
So, like I mentioned above, the weigh in the fuselage is probably not all in the tail, unless you have to mount the battery all the way forward in the under-wing compartment. The motor battery in mine is located somewhat aft of F2, in the same location as is shown on the plans, pretty much centered over the C/G. That wasn't an accident, I wanted to be able to fly with a variety of different batteries, so I went to some pains to make sure the battery was on or at least very close to centered on the C/G.
Don, I could use a little help in plugging in the
different wires to the receiver. I have tried several
different combinations, used V-Tail setting as well as
Elevon setting and I can't seem to get it right. I am
plugging my spoilers into channel 5, my lead from the
ESC (with the center red wire omitted)into channel 3,
and my radio battery into what ever is left after I
plug in my left and right servos.
Since the primary roll control on this model is the rudder (or ruddervators, in the case of the V-tail), then you should use the aileron and elevator channels (channels 1 and 2 on most Futaba radios if I remember correctly), with "elevon" mixing, and steer the model entirely with the right stick.
To get the control travels correct with a V-tail, you may have to experiment with swapping the channels the two servos are plugged in to, as well as playing with the servo reversing switches, and with which side of the servo you put the servo arm (i.e.: pointing towards the fuselage side, or pointing towards the fuselage centerline). You may have to experiment, but some combination of those options should give you the correct control directions. It's also very possible that the two servos will need different arm orientations, one towards the center, the other towards the fuselage side. I had to do that with my Chrysalis 2-M sailplane fuselage, which uses the V-tail and a Futaba transmitter.
Remember, "left" stick should make the left ruddervator go down, and the right ruddervator should go up. A V-tail works by yawing the plane, not rolling it, so you do not set up ruddervators the same as you would ailerons!
Of course the elevator function is the same, pull "back'" on the stick and both ruddervators should go up.
The other option that some folks with fancy computer radios like is to use V-tail mixing for the ruddervators, but then mix the ailerons to the rudder by a factor of 100%. This allows the model to be steered with either the rudder or the aileron stick.
Finally, I am a intermediate flyer. I have flown
successfully my gas trainer, electric easy star, and
zagi. On my maiden flight I would rather just use the
power system and then trim the plane when it is in
the air. Would you caution me against this and do the
throwing procedure without the power system? I just
dread throwing the plane on the ground with no power
and possibly crashing the plane before I even fly it.
Power on the first flight is OK, especially for someone with your skills, but it does complicate things, especially on a high-powered brushless setup. The answer is to plug the speed control into the throttle channel, and use about half throttle for the first flights until you get the model trimmed out. That should be enough to get the model into a shallow climb, but not so much power that it will go crazy if something is a bit out of trim. In general, launching with partial power is a good way for sport flying. I give it about half throttle, launch the plane, get my hand back on the transmitter, take a moment to make sure everything is behaving normally (by that point the model has only flown a couple seconds and only a short distance), then smoothly advance the power to full, smoothly rotating to the model's max-performance climb attitude (maybe about 10-20 degrees short of vertical in the case of mine) as the power comes up to full. It's graceful, controlled and a lot safer than a violent heave immediately into a full-power climb.
However, for contest work where you have a limited number of seconds of climb and every second has to count for every inch of altitude you can get, a full power launch is appropriate. In that case, the answer is to have tested the model thoroughly to make sure everything is in trim, and that the model will go into a perfect full-power climb the moment it leaves your hand.
Don Stackhouse
DJ Aerotech
|
May 17, 2012
