Speed,Combat,Scale,Racing > Carrier
electric carrier rules
john vlna:
sorry Melvin, but the rule does work. The power you get from an electric system depends on the size of battery, bigger battery,more weight, more power.. I have flown electric carrier for about 6 years now and I believe it works and is comparable to the glow classes. They have an overall weight limit, and in electric it is the same thing. I don't see a problem.
John
Mark wood:
--- Quote from: bill bischoff on December 10, 2021, 07:51:00 AM --- I think the point is this: In IC classes, you are limited by displacement: in electric classes, you are limited by weight. You can use as powerful a system as the weight will allow. This is not the case in IC. Following the logic in electric, if I can build 60 powered plane that's under 3.5 lbs ready to fly, I should be able to fly it in class I.
How you define classes in electric is somewhat arbitrary. I think the simplest way would be by battery voltage (cell count). It's really only an issue if you try to combine IC and electric in the same event, so don't! Use record-ratio scoring if you aren't going to provide separate awards.
Bill Bischoff
--- End quote ---
The events aren't combined within the rulebook. The logic of using a .60 in Class I as an example isn't truly valid as the classes limit the power by displacement. In electric that could also be done but would be hugely difficult to enforce. So, for electric this is done by weight. In reality the weight method for electric is no different than displacement in IC. In IC the limits are weight of the airplane and displacement, no limit is placed on how much fuel can be used , however over the run a .60 will consume more fuel than a .40. Weighing the airplane at the beginning of the run the Class II airplane will weigh more than the Class I due to the amount of fuel onboard. The amount of energy contained within that fuel is will determine the outcome of the run. Less fuel, less available energy, less work can be performed therefore less performance. The displacement and it's conversion efficiency limits how much of that energy can be used. So, in essence, the displacement limit in turn limits the amount of fuel and the result is a defacto maximum weight limit. Putting more fuel onboard wouldn't result in any better performance. The weight of the fuel divided by the energy content is the energy density.
So take that concept to Electric and figure out two things. One how much energy (power) would be allowed and two how to enforce it. Cell count alone does not do that and then we transition to cell plus storage capacity (MAH). So we have a "good rule" max 4 cells and 220MAH storage. The question, how do I as CD enforce these? The TP 4s 220MAH battery is a different package the a HS 4s 2200MAH which is different than an HRB 4s 220MAH battery. Me and my helpers will need a long ever changing list of approved batteries. Enter energy density. The LiPo chemistry has a specific energy density of 50-70 Wh (Watt Hour)/Kg or 180-252 WS (Watt Second)/gram , therefore I could weigh the battery. It's at this point the relevance of voltage becomes somewhat mute.
Remember the above IC regulation vs performance. A really good nitro/methanol fueled glow engine produces about 7 Hp per cubic inch or 7 x 745.7 = 5,219.9 watts per cubic inch. A .60 sized engine then has .6 x 5,219.9 = 3,131.9 Watts output. I'm not in touch with the current speeds and time for the completion of the course but assume it takes 15 seconds to complete the high speed course. This would result in the engine producing 3,131.9 W x 15 S = 46,979 Watt Seconds (joules) over the run. We could translate this to a battery but we'd have to account for some efficiency losses and the engine efficiency is in the 40% zone converting fuel energy in to thrust energy so to complete this part of the run would need 46,979 Ws / 0.4 = 117,447.5 Ws seconds of fuel.
This could be translated in to a battery definition and this is would be how it reads - The Class II battery is limited to an energy capacity of 120,000 Ws. Okay so this definition is now nearly identical to the IC Class II definition as it is derived from the IC performance over the run. We could go further and say the empty weigh of the Class II airplane is 3.5 pounds minus fuel or battery. So I now have two rules to define the electric version of Class II and one definitions of the IC Class II airplane. Seems unfair to me, but wait..
We are still left without a good method of enforcing the rules. How do I limit the battery? I could use the list method or I could use the energy density method. Using this I can take the range of battery performance and specify the lower performing battery as my standard 180 Watt Seconds per gram. Take the 120,000 Ws seconds required for the course and divide by the energy density and I get the weight of the battery. That, as a CD, I can measure and enforce. So, 120,000 WS /180 WS/g = 667 grams. Just over a pound..!! This result causes me to ask why would I need to weigh the battery separately form the airplane and just add it to the maximum airplane weight. There ya go, the Class II electric derived from the IC Class II event. The 4.5 pound wieght limit on the E Class II makes perfect sense.
Peter Mazur:
The electric navy carrier events have been official AMA events for nine years and unofficial events under nearly identical rules for about five years before that. So the events aren’t exactly “new.” As John Vlna has pointed out, the events work well under the present rules. The rules are easy for the CD to enforce and for the contestants to understand and work with. There are no “tricks” that will allow someone to leap ahead in performance. Performance comes from selecting hardware (motors, speed controllers, batteries, props, etc.) and from building and flying skills. The scores for electric events are pretty similar to those for gas events, although the scores for the gas events at the highest levels of competition are higher than for electric because they are not usually limited by the amount of fuel carried. Competition in combined events can, if desired, use record ratio. In short, the rules for the electric events, like those for the gas events, meet the needs of competition very well. I don’t think that changes to the rules are needed, and any major changes that obsolete existing equipment would be harmful to the events.
Pete
john e. holliday:
The best thing to help an event is to see what is being used. What helps the most is getting out and practicing after you do get the equipment. Back when I was winning locally no one wanted or could afford the McCoy Red Head 60 with Bill Johnson throttle set up. The Sterling Gaurdian was kit of choice. Also hanging a plane was not mastered yet. I still remember Jim Finley checking watches after I posted a score low speed of 25 mph on one of the windy days at Wichita. If I had got out and practiced more especially after getting a Rossi 60 I may have done better. Not too many people want to hang onto a screaming 60 to launch for a person. Still have my McCoy 60 but it needs a lot of work from sitting too long. My excuse is I need more practice, not rule changes. R%%%%
Mark wood:
--- Quote from: john e. holliday on December 10, 2021, 03:52:09 PM ---The best thing to help an event is to see what is being used. What helps the most is getting out and practicing after you do get the equipment. Back when I was winning locally no one wanted or could afford the McCoy Red Head 60 with Bill Johnson throttle set up. The Sterling Gaurdian was kit of choice. Also hanging a plane was not mastered yet. I still remember Jim Finley checking watches after I posted a score low speed of 25 mph on one of the windy days at Wichita. If I had got out and practiced more especially after getting a Rossi 60 I may have done better. Not too many people want to hang onto a screaming 60 to launch for a person. Still have my McCoy 60 but it needs a lot of work from sitting too long. My excuse is I need more practice, not rule changes. R%%%%
--- End quote ---
Like I said, I was never really a carrier guy but that never stopped me from leaving the speed or racing circle to help. I'd hang on to either the McCoy or the Rossi. I remember that McCoy setup.
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