RC BEES of Santa Cruz County, Inc.

Transcription

1 RC BEES of Santa Cruz County, Inc. Newsletter March 2016 Editor: Alan Brown, 388 Aptos Ridge Circle, Watsonville, CA Phone: (831) Web site: volunteered to notify Watsonville Police of the Next Meeting activity so we won t get raided! th Thursday, March 17, at the EAA building, Aviation Way, Watsonville Airport, 7:30 PM. Treasurer s Report Beginning Balance Income Dues Subtotal Expenses D & G Sanitation Fun-fly expenses (food, etc.) Subtotal Ending Balance $12, $ $ $64.95 $25.45 $90.40 $ January Meeting The general meeting opened promptly at 7:30 p.m. with eighteen members present. The previous minutes were O.K d. It was noted that the fun-fly expenses had been somewhat over-stated, but that, together with expenses for the night-flying fun-fly would be corrected in the next treasurer s report, which is in fact shown above. The upcoming night-fly to be organized by Max Trescott with help from Dan Morris and Jacob Boracca, was discussed. As there will be activity and aircraft with lights on board, Keith Wigley Dan Morris said that he wanted to schedule something for April, perhaps a flying wing pylon race or perhaps an invitational teaching-to-fly day for local Boy Scouts. (In fact, we will have an event on Saturday March 26th where new member Melissa Pardo will bring a group of her fellow-cabrillo engineering students for model flying lessons). Having written a partial article on tails, canards and longitudinal stability for the February newsletter, Alan Brown asked whether there was enough interest to continue, which was affirmed by the members present. So there ll be more tacked on to this newsletter. Steve Boracca noted that we are all required to have both AMA and FAA identification on our models. The club will enforce the AMA requirement, but not that from the FAA. It was noted that the Monterey Bay Sanctuary has flying restrictions on drones. Members who fly close to the beach may want to check their website, to be sure they are in sync with their requirements. A discussion followed on repairs to our flying field. It seems that we could use some more gravel. Mike Evans suggested base rock from

2 Granite Rock, and he could volunteer to pick it up if authorized. Steve Boracca thought that the shed needed painting, and John Williams suggested that perhaps more work than that is needed. Laurie Trescott noted also that we had recently lost two of our chairs. Steve also noted that it would be useful if any of us could donate old transmitters and receivers for the benefit of potential new members who are perhaps just thinking about the hobby. He volunteered to store anything that members might donate. This looks like an old Playboy free-flight model with a McCoy 19 Redhead engine, brought in by George Ribeiro. It is followed by a Piper Pawnee ARF, complete with all night lighting installed. It was also pointed out that our club trainer has seen better days, and it was suggested that it might be replaced by an E-Flite Apprentice, which has SAFE (automatic stability) technology, a big recent improvement for trainers. John Williams proposed, Jay Friedland seconded, and all voted in favor of this purchase. This was followed by an inconclusive discussion on whether the animal recently seen at the field was a bobcat or a mountain lion. At least everyone agreed that it probably was not a lion, tiger or leopard! The lighting wasn t too obvious, so we took it outside for a self-illumination shot. No other outside lighting! (John Williams airplane?). Old joke department: Two men are driving down highway one in a convertible, and the passenger asks Why are you throwing this powder over your shoulder every few miles? It s anti-tiger powder. That s crazy, there aren t any tigers within eight thousand miles of here. Pretty good stuff, huh? Show and Tell Regrettably your scribe was overwhelmed by the number of airplanes that were shown at the February meeting, and didn t take very good notes. So if you see pictures without, or with incorrect captions, please excuse him. This looks like an old Playboy free-flight model with a McCoy 19 Redhead engine, brought in by George Ribeiro. It is followed by a Piper Pawnee ARF, complete with all night lighting installed. Benno is actively pursuing his rockets. Here s his latest small model. The S-5 kit to the right from George would be a great model for one of our seaplane enthusiasts. Call him.

3 And here s his more serious stuff. This rocket with parachute attachment will be his entry for the upcoming Science Fair on March 12th. Dan Morris and Jacob Boracca had their latest trirotors on show. Nickolai de Malvinsky did a great multi-color treatment on his powered sailplane. This is just one of the colors he showed. Here s his fairly serious quadcopter complete with g.p.s. and high quality camera. Jacob was in the thick of things, as usual. And Dan has converted one of his flying wings into a canard 1930 s airliner, complete with lighting. The meeting was formally closed at 9:15 p.m. Night Fun-Fly February 20th Dan Morris gave you all a full account of the festivities the day after the contest, so I ll just

4 supplement it with pictures by Laurie Trescott, Jay Friedland and myself.. Here s George McKeon with his powered glider. Max Trescott illuminated the end of the runway to help landing airplanes, and provided illuminated headbands. See George on left. Jay Walker and Don Edwards ready for an evening s enjoyment. Nice-looking Stick. Next column shows Dan Morris with his three-tailed transport. Benno s T-28 waiting for take-off.

5 I think that this is Jacob s airplane 3-D ing. Or is it Benno s? Here are the plastic parts, and here they are installed, ready for motors. The highlight for me was when Nickolai dropped two illuminated paratroopers from his airplane. Sorry, I don t have any photos. Down by the River A week later we were out doing our usual things, and Nickolai appeared with yet another new airplane, this time an Avios Riff Raff from Hobby King a Reno racing version of a Hawker Sea Fury. What a pretty airplane, but a little bit too heavy read fast- for me!! 6s LiPo battery, 3648 size motor, weighs 4.6 lb. at 47 wingspan wow! Jacob, meanwhile, has acquired a 3D printing machine, and is industriously making plastic parts for his latest Penta-VTOL; yes, that's five motors. Finally, as a highlight to the day;s flying, Benno's piggy-back rocket shell on Jacob's airplane, and released in the air! Look back in Show and Tell.

6 Late Additions: Aero 101: Tails and Canards (Part 2) Max Trescott took a nice video at the night-fly, which can be accessed at Check it out. You'll enjoy it. Last month we discussed aerodynamic centers, and their relationship to longitudinal stability, and how to avoid low speed pitch-up and stall. Now we'll expand on the theme of planform effects. As a reminder, here's our simple airplane. Also, the Santa Cruz County Science Fair was held on February 11th, and four of us acted as judges, Jay Friedland, John Kent, Alan Miller and Alan Brown. My apologies if I missed anyone out. Jay's son, Benno, was picked to participate with the rocket you saw earlier, and here is a representation of his piggyback flight path at our field from his rocket instrumentation, together with his entry display. Well done, Benno! Center of pressure Aerodynamic center a b a tail area =nx where "n" is less than one b wing area Swept wings are not more prone to wing tip stall than straight wings. It just seems that way because they often have higher taper ratios. However, if a swept wing does stall at the wing tips first, then this is just like a tail stalling before the main wing - low speed pitch up. So the effects of tip stall on a swept back wing are more dramatic than for a straight wing. Conversely, a swept forward wing is almost guaranteed not to pitch up if the tips stall first. It s thus no surprise that the X-31 research aircraft designed to research post-stall characteristics has swept forward wings. One more thing. Despite the tendency of low aspect ratio surfaces to stall at higher angles of attack, we can still screw things up by putting a horrible airfoil section on them so that they will get flow separation at a fairly low angle of attack. A good example would be a tail made of 1/4" sheet balsa with absolutely no leading edge streamlining. This again becomes an airplane asking for drastic pitch instability at low speeds, particularly if it s teamed with a very fat wing which will not tend to have premature flow separation. We have probably all seen examples of model airplanes with these very scary characteristics. Now just a word about vertical tails, particularly on canard or tailless aircraft. Here s a picture of Burt Rutan s Vari-Eze, a predecessor of the Long-EZ.

7 together perhaps with some aileron movement to get a coordinated turn. However, when the rudders are so far away from the aircraft centerline, the drag that results from the rudder deflection will, for the inboard rudder, help the airplane to turn, but the drag from the outboard rudder will pull in the opposite direction. So it makes a great deal of sense to only have the inboard rudder move in a turn, while the outboard rudder remains fixed. This can be accomplished either mechanically or by computer setting of end points with separate servos for each rudder. Note that the forward, canard surface is of a high aspect ratio, and one of the claims for the aircraft is that it is unstallable. Burt understands the high aspect ratio canard story very well. He s a good aerodynamicist! Note also that the vertical tail surfaces are out at the wing tips. They can be used as drag brakes by having them both move outwards. However, for rudder operation, it makes a great deal of sense to only have one rudder operating at a time. If you want to turn to the right, it would seem logical at first sight to crank the trailing edges of both rudders to the right I hope that this discussion clears up a few points about how our airplanes fly, particularly the unusual ones. And that's your newsletter for this month. We'll see you at the club meeting on March 17th (sorry, no green beer served!), and at the Cabrillo College engineering department flying lessons day on Saturday, March 26th.