PeterF

When I was looking after noise tests at my club, larger models were tested restrained on the ground with the props and engines above grass, not a hard surface such as paving or tarmac to dampen reflected sound from the ground. Based on measurements of several planes both on the ground and held at waist height I found that measuring on the ground increased the measurement by 2-3 dBA. Therefore, we allowed an extra 2dBA for planes measured on the ground. Another factor is being in front of a prop at WOT, even 7m away. A few years ago I recall an incident report from the BMFA where a prop on a large petrol engine had come off during a noise test (can not recall the engine capacity). From memory there was a recommendation to have netting between the model and the tester or have the meter on a tripod with maximum value recorded. How netting impacts the noise measurement I do not know.

I have not seen anything like this. With Jeti having a niche market I watch the RC Groups Jeti thread as that has some experts who contribute including Harry C. There is also a German sire but translation is required. https://www.rcgroups.com/forums/showthread.php?1693301

Graham, Have a read of the linked page. https://www.jetimodel.com/support/technical-support/differences-in-jeti-duplex-telemetry.html I am still not sure exactly what the difference is myself as I only use the full EX receivers.

As I swapped to the DS-12 from the Hitec Aurora9 I lost the side sliders, but then I hardly used them on the A9. I bought some moulded resin levers to add to the rotary knob potentiometers from Hepf in Austria. Although they acted like sliders they were not as easily reached as side sliders and I was not keen on them. As I hardly used the sliders anyway, I swapped both rotary potentiometers for switches. Hepf now sell aluminium sliders which appear more robust than the resin ones I had. https://hepf.com/Alu-Drehgeberset-Blau-fuer-seitliche-Potis-passend-zur-DS12

The main dealer is eSoaring Gadgets who also trade as Jeti UK. I do not know if they do repairs in the UK or manage them through Jeti.

My club has a 3.5 acre leased field with a main 15m x 80m runway with a smaller cross runway. We have a shipping container club hut with water heating and basic camping type kitchen facilities. Solar panel and battery for flight pack charging. We also have a couple of slope sites which we pay an access fee to the landowners to use. We have monthly club nights but these are now low key affairs. As we lease our field we are a limited company so we also pay some accountant fees. Club members are around 50 with an annual fee of £60.

I purchased a DS-12 carbon model with all upgrades loaded in summer 2020. I am really pleased with it and have no concerns. I fly only electric from small hand launch models up to 25lb EDF. The telemetry is great and all my models have current and mAh counting telemetry on the flight packs so I use battery capacity to monitor flight times not timers. I also fly some thermal gliders and have been 600m vertical and 1100m ground distance with no concerns about radio link. If you are wanting telemetry then you can manufacture your own sensors based on a website called RC Thoughts. This website also has a lot of what are called LUA apps, which are small standalone programs that can control calculations with telemetry and display the info in a more user friendly was such as battery capacity by percent so every model just works on that basis. To get you started there is an excellent Youtube channel by Harry Curzon who goes through lots of the programming possibilities with JETI radios and with an accomplice publishes some excellent LUA apps.

I only started flying in 2000 with a 2nd hand Futaba FF8. When I converted to 2.4gHz I looked around and chose the Hitec Aurora9. At the time there was lots of chatter about brown outs and reboot times. The Hitec receivers allowed you to connect power direct to the Rx circuit at up to 35 Volt and power the servo bus separately. As I was electric flight only, I could connect the flight battery direct to the Rx power and then the BEC or separate battery to the servo bus, no chance of brown outs if there was too much load on the servo bus. Additionally, the Hitec Rx had inbuilt telemetry for the Rx voltage (not the servo bus voltage though) so I could monitor the flight pack. At the time, this was quite an advantage. Moving on, I was looking for a replacement because I wanted more telemetry, some more channels and a system with some redundancy in as I was moving to larger models, Hitec stopped their 16 channel development. I ended up casting around and at the time Jeti had just bought out their DS-12 model, a plastic case Tx with fewer controls and channels. Luckily at the time I had been doing some consultancy work to top up my pension so I went ahead and bought that complete with all the Rxs that I would need and some telemetry. Brilliant piece of kit and fairly straightforward to learn to program. I also dived into the LUA programming language that could be used to write apps to augment the telemetry, luckily I have programming knowledge from my working life writing Excel macros so this was a good find. I also found RC Thoughts website with plans for home build telemetry, all models have amp hour counters on the flight batteries, brilliant for monitoring your flights, no more working from timers. Buying into Jeti had opened up a whole new arm of the hobby and I am very happy with how well the change worked out.

Good point, if you have another measurement device check the battery with this as well as a cross check. I am currently looking into a battery with an odd cell and the cross check confirmed the imbalance was not due to the charger balance leads.

Can your charger do a balance without charging. If it can it will bring the high cell down to the same voltage as the others. Then discharge to storage voltage 3.85V per cell. If the odd cell goes back out of balance then it has probably reached end of useful life. If all cells remain reasonably well balanced at storage voltage then charge back up again and watch the voltage during the charge.

The Futaba Tx incidents listed above going into full throttle on going into memory settings. Could this be related to Futaba having reversed throttle direction to other makes and perhaps the Rx failsafe not being set if the transmission is shut down on going into model settings. It is many years since I flew with Futaba radio equipment so I can not recall this in detail.

The line drawing on the plans shows a long aerial wire from fuselage to tail indicating 35MHz which definitely dates it.

For smaller models up to 6S I use the BEC in the ESC after making sure that the BEC rating is adequate. I have had one ESC failure doing extreme arobatics with full power spinning where I believe that the extra gyroscopic loading on the motor from the spin overloaded the ESC but it did not blow the BEC so landed dead stick OK. For larger models up to 6S I use the ESC BEC subject to a high current rating coupled with a back up battery through high current Schottky diodes to provide higher reliability. For larger models above 6S with opto ESCs I use either 2 battery packs or a separate BEC and back up battery, again with Schottky diodes.I Your choice of a separate battery pack with basic RC switch is in my view no more reliable than the inbuilt BEC in an ESC as long as the BEC has enough current rating. In the early days of electric flight a lot of ESCs had BECs that had too low a current rating or were of the type that generated a lot of heat (linear BEC) on anything above 3S packs. The mechanical switch is probably less reliable than a quality inbuilt BEC that has an appropriate current rating. Both habe single points of failure. The only RX power related crash I have had is black wire corrosion on an IC powered model, something that should not occur on a BEC powered model.

We had a member of our club whos electric model unexpectedly went to full throttle. Fault finding revealed a broken wire in the Tx on the throttle potentiometer which caused a full throttle signal. Whilst restraints and arming switches might not always catch such an issue they would reduce the probability of a fly away. In the incident I refer to it was a helicopter and it rose from the ground cutting him on the face and just missing an eye. It was reported in the BMFA news at the time.

With you here, I swapped my arming switch to one of the lift to operate types to avoid inadvertent operation. Also on my Jeti Tx I have coupled the arm switch with throttle position needing to be at zero. Most ESCs need the zero throttle before starting, but with an arm switch they get the zero throttle at battery connection with the arm switch in the disarm position, so they are ready to go when the arm switch is armed.

The 125degC on the heatshrink may just be the activation temperature for the heatshrink not an indication that it is a temperature sensor. Most temperature probes I have seen only need 2 or 3 wires, not sure why it would have 3 x 3 connectors.

For RC with typical flight times the battery will continue to scale linearly with model weight, the power required is linear with weight, so the energy stored will be linear, so the battery capacity and weight will be the same. For full scale they want longer duration. There is also the cost element of higher upfront costs, as Jon says, turn around time is very different, you either have to buy loads of batteries or charge them at the field. On my largest EDF plane I have to accept 40 minute recharge because I will not buy another set of batteries at several hundred pounds. I am happy to compromise like this. For my smaller models I can afford multiple packs and not be restricted. This is one of the reasons for not commonly seeing larger models with electric power. Your battery and flying weights fall within the scatter on my charts, so they add to my data confirming the proportionality, but you need more than 2 examples to see the average trend.

Typically most of my propeller drive planes are 8-9 minutes with aerobatics thrown in but some like my quarter scale Moth will do 15 minutes. The only ones with limited flight time are EDFs where I get 4 to 8 minutes depending on the model.

I run a wide range of electric aircraft and my feeling from building and specifying the equipment in them was that the battery weight and motor weight increased proportionately with the aircraft size, not exponentially as you state. Why would they increase exponentially, it is well known that a motor weight for good performance is typically 1g per 3W of power output, and for a standard type flight you want 100-125W/lb of model weight. This suggests that both power and by definition motor weight will increase linearly with model weight. As the battery needs to provide a certain power for a certain period of time, then battery size will also increase linearly (proportionately) with model weight. I have always kept a spreadsheet of all my model and power set up details with Wattmeter and rpm readings, model weights, battery weights and flying weights. So I have looked at that record and plotted 2 graphs, one showing battery weight vs flying weight and one showing motor weight vs flying weight. For the purposes of this analysis I have removed all my EDF models, the ones shown are propeller driven only. It is known that EDFs require more power and larger batteries than the same weight model with propeller drive, but if plotted on their own, the EDF follow the same linear trend. The data I have shows in the first graph that over a wide range of flying weights (0.3kg to 8.2kg) the battery weight is proportional to flying weight. There is some scatter as I only use 4 battery types for all these planes, plus there are a wide range of model types with different power to weight ratios (more later). The second graph shows that the motor weight is also on the whole proportionate to the flying weight, but the scatter is somewhat larger in this case. This is due to the different power: weight ratios required for the different flying styles. For example at the 7 to 8kg part of the charts are 3 planes all about 2m (80") wingspan. One is a 3D aerobatic plane, once is a Mosquito and one is a quarter scale Tiger Moth - pretty easy to decide which is which. I do not have weights for the ESCs but these will be dwarfed by the battery and motor weight and will probably also be proportionate to the power. Your other question around the flying weight of the different setups. A fair number of my models were glow powered and I converted these to electric, including the 3 large models described above. In every case I have found that the flying weight of the glow powered version and the IC version was very similar. In fact the mosquito was 17lbs 10oz glow and 17lbs 12oz electric. I do not know what it would be for larger petrol power as I have never flow petrol.

Answering a couple of questions raised above. LiFe batteries use Lithium Iron Phosphate which is less chemically reactive than the lithium cobalt oxide or lithium manganese oxide typically used in Lipo batteries. This is why they have lower C ratings and need to be larger / heavier for the same capacity. This makes the LiFe batteries safer as they are less likely to catch fire. Some car batteries are now converting to lithium iron phosphate and boats, caravans and RVs use this type aswell. However, for objects where weight and volume are key they do not tend to find favour. The issue of why we often charge phones etc. In the house has been raised and answered very well above by @leccyflyer. One key difference in RC flying what we consider as normal use, i.e. discharging the battery in 3 to 10 minutes is actually abusing the battery, in no other application is a battery discharged as quickly, cars, phones, laptops, power tools, ebikes etc are all discharged over periods of 1 to 24 hours. Even those of us who look after our batteries well will get cycle lives measured in 100s of cycles so our cells age very quickly and if not monitored can lead to charging problems. Another factor is lithium batteries do not like being charged when cold and this can damage them, but we often keep them in sheds, garages, so do people prewarm them or just charge them. I keep mine in a temperature controlled store during winter to avoid this.

BMFA battery safety booklet can be found at https://britishmfa.sharepoint.com/sites/public/Handbook Update/Forms/AllItems.aspx?id=%2Fsites%2Fpublic%2FHandbook Update%2FHandbook%2C Gudiance %26 Codes of Practice&p=true&ga=1 Another cautionary thread on here. https://forums.modelflying.co.uk/index.php?/topic/47237-charging-lipos-a-lesson-learned-the-hard-way-and-how-the-big-guff-met-its-end/ Join a club, you will get to know lots more information from interaction with other members and absorb knowledge just be being there.

Like many have said there is no fixed answer to this and if you joined a club you would see a lot more different types of models and equipment. I now fly exclusively electric and have 2m wingspan 30cc equivalent electric power models. A couple of our club members have 50cc equivalent electric power models. I am happy with it but there is the odd model that I do miss the ambience of the IC noise.

There may be small quantities of byproduct methanol but these are small compared to the global market. The vast majority of methanol is produced in very large petrochemical plants from natural gas with a single plant producing between 2,000 and 6,000 tonnes per day of refined methanol. As the feedstock is natural gas methanol is far from cheap. Before retiring I worked for a company designing methanol production plants.

I always buy from Overlander, much less likely to have old stock that a smaller seller may have. Although they should be at storage voltage, they do discharge slowly over years.

They are not internationally distributed as Tornado motors so have little visibility. Additionally Overlander do not publish all the motor specs. Find another motor of similar size and KV, they are probably generic chinese makes.