Dedicated to the Promotion of Electric Propulsion in all types of Aeromodeling

Brad’s Corner for June/July 2017

300XHey Folks!
We didn’t see much May Gray, or June Gloom this year, and now the summer heat is on us! Most important is to bring plenty of liquids with you when you come for a day of flying. Last summer we had a member nearly go into kidney failure because he simply wasn’t getting enough fluid. Sunscreen is also your friend!!  I am going to once again bang my drum about fire safety. The outlying field area is now extremely dry. A small fire can turn into a big problem very quickly! Thanks again to those people that keep their extinguishers handy and are not afraid to use them.  A few other things to think about: there is a lot of dried up pollen on the weeds at the moment. If you have allergic responses, please be careful. If you have trouble breathing after a walk in the field, please mention it to someone so we can, at a minimum, keep an eye on you – or call emergency responders if necessary. I walked out for my plane with Tom and Tuan almost 3 weeks ago and still have blisters on my lower legs from the pollen. Finally, with the recent heat comes the possibility of snakes. Watch your step and listen for indications. Most of all, BE SAFE!!
A couple of interesting items: We had a couple of people lose some large and expensive aircraft this month. Even though it still stings, I am going to mention the issues in hopes of you avoiding the same pitfalls. Richard lost his 105 inch Laser due to a propulsion failure. The post mortem indicated the possible failure point as the connectors in the wires between the ESC and the motor. At least one of the connectors was able to be pulled apart with little or no effort. As we move to higher amp systems there is quite a bit of current going through these wires and a good chance that your connectors are heating up. I have seen a motor connector on one of Scotts jets get so hot that it melted the solder out causing failure. This type of heat cycling can cause bullet connectors to loosen over time. With most of the available HV speed controllers, there is an option to reverse the motor using the software or programming card, so you don’t have to swap wires to get the direction you desire. In these instances it would be preferable to just solder direct and leave the bullet connectors off completely. If this is not an option, or you just cannot bring yourself to move away from your affair with connectors, Randy mentioned a good solution. After he verifies that his system is sound and turning the proper direction, he goes back over each connection with a high quality heat shrink to ensure they do not come apart. After all, our intent should be to make the system bullet proof instead of making it easier to move gear to a different plane after a crash… A week after Richards loss, I also lost a 105” Extra on its second flight due to what ultimately came down to me pushing to get a few flights on a new model – even though I knew there were some conflicts with the way my radio system was configured. There is a known ( not to me at the time ) issue when using Hitec 7950th HV series servos on Spektrum Powersafe receivers with unregulated 2 cell lipo batteries. I tried to work around the issue by using a much lower capacity 6v LIFE battery which made it through a gentle maiden flight, but couldn’t handle the load when I threw all 7 high draw digital servos quickly to their end points in a full power snap roll about 30 feet up from take- off. The receiver browned out and recovered, but the motor would not re-arm – so I lost a battle with altitude. I have since re-built, and maidened the replacement (Pictured above), but will take away an expensive lesson: There is always tomorrow to fly your plane. If something isn’t EXACTLY the way you expect, take it home in one piece and figure it out.
Randy also threw out another pearl of wisdom this month: “Don’t forget your HOLE.”
Your vent hole that is. Sometimes you need to be inventive in allowing cool air into your airframe, and allowing warm air to exit.  A good majority of us are using over 1200 watt power systems. Even if your system is 90% efficient, that means 120 watts of waste heat being generated. When was the last time you closed your 40 watt soldering iron in the palm of your hand? Heat is the enemy to the magnets in your motor, connectors, batteries, and your speed control. To keep everything operating trouble free – we need to ensure we keep things as cool as possible. An old rule of thumb is to have twice the area on the outlet side than the area of the inlet vents. This ensures good cooling flow without pressurizing your airframe and blowing your hatch off (Right Raphi?)


Due to lack of support from vendors, and life in general getting in the way, we were not able to pull together a solid raffle for the 4th of July. I still have and will hold the items that were donated, and we will attempt to have a good show for the next holiday – which will be Labor Day on 04 September. We have some banquet money in the coffers, and hope to fund the remainder for the banquet with this raffle.
Speaking of the 4th, we will again be expecting a full day of flying. The board will serve a hot dog lunch around noon with chips and soda. We cannot plan for the numbers of people, so it will be on a first come, first served basis. If you plan to stay all day, please bring picnic supplies and beverages with you. We will have the clubs small BBQ available, and one or two members have agreed to bring and share their personal GAS BBQs with people that want to bring a protein and cook on site. No Charcoal grills please. Also, as part of mission bay park- glass bottles are prohibited. If you bring an adult beverage, please fly responsibly. Feel free to bring family and friends. This is the perfect time to bring your night flyers and light up the sky prior to the fireworks. For those who have not seen the Sea world fireworks from our field, we have a perfect front row seat. And there is a pretty decent exit point using old Sea world drive to Friars road east and hooking up with interstate 8 in mission valley. We will probably leave the gate open until around 6:00 PM at which time we will close it and lock it to non-club members. Jim will again post the ‘Members Only” sign. Over the last couple of years there have been issues with inebriated revelers causing problems at our site and I want to minimize that chance. If you arrive and the gate is closed, feel free to open – pass through – and close/lock it behind you. I don’t want anyone to get into a physical alteration, so if it comes to that with someone trying to force their way in, just let them in. Please don’t get upset if you leave the gate open behind you and you are asked to go back and close it.
While on the subject of the gate, PLEASE close the gate if you are the last one out! Again there have been reports of members arriving in the afternoon to an open gate and non-members on site flying over Sea world drive and the marsh refuge area. Kind of hard to argue that it’s not us if they are standing on our site while doing stupid stuff…  Close the gate.

We had an issue last month on meeting day about the preparation of hot dogs for members. It involved comments, yelling, and hurt feelings. I proposed to the board during our recent meeting that we stop doing lunch altogether on meeting days. My feelings are that if my volunteers are getting yelled at, we don’t need to do it. I was voted down by others on the board, but to be frank – I will not tolerate further abuse to the folks cooking the dogs. If there is an issue, come to me.
This month’s event is Warbird Day starting at 10:00 AM on the 24th. Come show off your favorite bird for a chance at $150 in prizes! Club meeting and Costco hot dogs to follow.
Have a great month!