Peter Jenkins

All good questions Nigel, but there will be some cheapo servos where all the tolerances are at the tight end and it's a wonderfully performing servo. Then you get the other one and it's rubbish. At least with a "name" servo, if you get a problem you can send it back and get a replacement for the dog you had in the first place. Plastic gears are fine but when you have a large petrol engine with lots of vibration it may cause problems. However, metal geared servos may develop more slop with a lot of vibration. There is, I'm afraid, no dead cert way of knowing how good the servo that is a cheapo one will operate and last. On the issue of longevity, you need to fly aircraft a lot more than the average club pilot does to come up to the amount of flying, with the same aircraft, that competition aerobatic pilots do. The option remains to replace gear trains if you detect wear. If I ever had a hard arrival(!), I would replace the plastic gear trains of the servos affected to be on the safe side. It only takes one broken gear tooth to jam the servo and cause mayhem. Buy cheap and you could be lucky most of the time. Buy expensive and you are paying for better QA throughout the manufacturing process. It isn't always a case that a named brand is more expensive for no reason.

Funnily enough, it was Hitec 5625 servos that caused the problem on my 2 m aerobatic aircraft! These days, there are an increasing number of metal geared servos that maintain their resolution over time. Perhaps they are using a different alloy for the gears? There are a number of reasons that most club pilots don't notice the poor centreing of their servos. Apart from the obvious one that they are still relatively inexperienced and are just struggling to fly the aircraft, the other major reason seems to be a failure to trim the aircraft properly. I have been handed models to try out that have been trimmed and immediately have to re-trim them to the amazement of the owner. I think it comes down to the ability to see what the aircraft is actually doing. The other reason linked to this issue is that they very rarely fly in a straight line for more than the briefest of moments. If you try and fly in a straight line without climbing or diving for the length of the patch you will usually see an out of trim situation. Even when aerobatics are flown, they are usually very small figures and there is a lot going on such as wings not level when loops are started to there are other issues beyond trim that occupy the pilots mind. Flying with the wings level is not so easy! It may look like wings level but to me the wing is banked. Colleagues say to me, how do you know the wings are level? The answer is that if you pull up into a loop and the aircraft goes to the left you had left bank on and vice versa. If you pull up and the aircraft goes straight, always assuming you have set the correct side thrust, then you have the wings level. Servos that do not centre accurately are also responsible for these characteristics. So, sometimes its difficult to apportion blame correctly and fix the problem. It could also be a combination of things - and usually is.

That's why you can afford all those models and can stash them in the house then! 🤣🤣

Nigel, check these out. They are listed at 46 g so a bit lighter than the standard but almost twice as heavy as a mini. They are currently on sale from Bondaero.

Well, if you don't have any rules for spoken and written English there would be plenty of scope to be misunderstood. I appreciate that not everybody cares about infinitives and whether they are split or not. I would just observe that there are also a lot of folk you confuse singular with plural construction such as "there's lots of things to talk about". Just imagine if we managed to get tenses mixed up. I went out tomorrow and flew my model. Of course, language always evolves and new ways of speaking which start off as slang or something someone says that sounds good to someone else and it is then repeated. Perhaps "My bad" and an example of that. I do wish though that we could see the demise of "Me and the wife went out to dinner". We wouldn't say "Me went out to dinner" would we? Where do you draw the line?

I never get over infinitives being split. If I do fall into that trap, I immediately correct myself. There are some, of course, who have no idea what splitting an infinitive means but you would think that BBC news readers would know that they shouldn't do that.

Hi Nigel There used to be a time when if you were flying aerobatics then you only used Futaba or JR servos. Those days have gone. However, for low cost servos that centre accurately and have good quality slop free gear trains then you really would do best to speak to Steve Webb Models - this is a link to their servo page. I once bought some expensive Hitec servos but they did not centre accurately as was pointed out by a then UK team member who test flew my aircraft. If you recovered from the vertical dive to horizontal and then released the stick, the aircraft climbed slightly and vice versa. The immortal words were uttered "lose them and fit Futaba"! These days, I use Align, MKS and Futaba with good results. Another factor to consider is that some servos, admittedly expensive ones, are programmable so that you can adjust dead band, centreing accuracy and so forth but you need to buy a programmer (link ). I think your best bet is to speak to a supplier who sells a wide range of servos and explain what you want and see what they say. If you are looking to pay less than £10 per servo then test them for centreing accuracy. Use a long light pointer firmly bolted/attached to the servo arm and check that the tip of the pointer returns to the same place when you drive the servo in both directions. At the end of the day, next to the aircraft you are using, the servo used has the greatest impact on how your aeroplane feels when you fly it. For an aircraft like the Gangster 63 which has a great aerobatic capability, pick the best servo you can afford.

I'm afraid, Martin, that our language has been invaded by Americanisms and that is just one example. "Visit with you", "right" said at the end of every sentence, and so on and so forth. Punctuation, spelling and grammar also appear to be in rapid decline although that seems to be laid at the door of the text message where brevity and the use of short forms reign unchallenged, Gr8, for example.

Nigel, this is the type of aircraft that you will notice the accuracy of good quality servos. Do not opt for cheap and cheerful otherwise they will not allow you to trim the aircraft accurately. A servo that accurately centres from both extremes and very small movements is essential.

Had the same issue with replacing the LiFe packs in my JR XG 11. £80! I felt I had to buy one and then took the old one apart (cut the heat shrink around the 2 cells) and found that there was a 2S LiFe charger on a PCB included! The input from the Tx charger is just a power input hence the need for a LiFe charger. Why they couldn't have included one fitted into the Tx is beyond me. I see that you can buy these LiFe charge boards (and LiPo for that matter) for around £15. So, my replacement pack, which has a much higher capacity than the standard 1600 mAh, was assembled around the charger and a suitably sized piece of heat shrink gave me a replacement pack at the cost of 2 LiFe cells with 3,200 mAh capacity. Is Spektrum playing the same game?

Can you get hold of a spinner with a heavy backplate Adrian?

David What an interesting day. Sounds a bit like " ..and what did you think of the play Mrs Lincoln" 🤣🤣

Does it say what units to use and does it give an equation to give a precise figure? Otherwise, Prof Google is merely telling us what most of us know. The OP asked for a way of working out control forces. I suppose one way to check, a bit rough and ready though, is to apply full power and check if there is any noticeable difference in speed of elevator movement from full up to full down compared with no power. Assuming this is a tractor engine and the elevator is in the full slipstream.

Hi Nigel Futaba S148s are rated at 3 Kg.cm at 4.8 v which used to the standard. If you put it on 6 v you get 3 Kg.cm. For a typical 40 size sports plane, a standard analogue, nylon geared, plain bearing servo with around 3-3.5 Kg.cm will do the job. There is no need for a digital servo, or metal gears although nylon gears have been know to get damaged if you bash a control surface when moving the aircraft around. For the Gangster lite, I would focus on getting a servo that centres accurately from either direction. That is most important for an aerobatic aircraft like the Gangster. Using cheap clone servos can be a waste of time if they have a wandering centre position. For an aerobatic aircraft, not being able to have a set position for any of the main surfaces just makes it difficult if not impossible to trim out. As I fly a 2 mtr competition aerobatic aircraft, I use digital servos as I can be sure that the controls will not blow back once I have demanded a set servo position so loop radius doesn't lose it's accuracy. If you want to use a digital servo then that's fine but make sure that the rest of the control set up is as accurate as the servo will be. Hope that helps.

One thing beginners should do is to bring their Tx handbook with them so those unfamiliar with a particular brand would be able to read how to, for example, set up the failsafe. Trying to work out where a function is hidden in an unfamiliar menu is not easy. When setting up a trainer all you really need are how to get to the rates, expo, possibly servo reverse, range check and tge already mentioned failsafe. You don't need mixing or anything esoteric like logic switches.

Following his triumph at the 2023 World F3A Aerobatic Championships in Australia a month ago, Lassi Nurila (Finland) was happy to allow me to use the photo of him holding my book. Alongside him is the photo of Christophe Paysant Le Roux (France) who while placing 5th in this years World Championships had won nine previous championships and held second place once. Photo courtesy of Mark Allen Photo courtesy of Mark Allen The latest edition aerobatic book checked out by 2023 World Champion Lassi Nurila and 9 times World Champion, Christophe Paysant-Le Roux Model Aircraft Precision Aerobatics – Edition 2 Amended A Guide for Beginners and Improvers. You won't find another book like this today! Ideal for you or as a present for someone keen to start or improve their aerobatics! It is available on Amazon as a paperback (£29.82) or Kindle (£8.99). The book has been bought in the Europe, the Americas and down under! You can also still buy a paperback from me be sending me a PM with your name and address. For UK addresses, the cost will be £18.99, including 1st class post, while my current stocks last after which, the price will rise to £21.68 which reflects the increase in printing costs charged to me by Amazon. For non UK addresses, I will get a price for postage to add to the basic cost of £18.38. There are 16 written reviews, 13 awarding 5 stars and a further 26 ratings giving an overall rating of 4.6 out of 5. It's worth reading the written reviews, some of which have been written by RCM&E forumites who bought my book. My book has also been reviewed in RCM&E for both Edition 1 and 2 and received very favourable comments. Andrew Palmer, the top New Zealand pilot at the recent World Champs ( he placed 21st) gave this review on Facebook “This second edition is a book I would thoroughly recommend to anyone starting out in aerobatic flying. It also contains some good words of advice for pilots."

The Grumman Panther looks superb!

Such a shame for the Aussies - tee hee!

Don't forget to ask permission from the field owner first and show them your BMFA insurance.

If you still find that you need a lot of down elevator trim, then it's worth looking at my suggestion. Good luck with the next flight.

David, if you can reduce thd incidence of the wing (packing under the TE assuming it's a high wing config) you will reduce the amount of elevator down trim needed as well. If the aircraft is stable it shouldn't need any more nose weight.

Makes me wonder how I learned how to start a diesel engine on my own aged 13!

Toto Why don't you go up to the field tomorrow and just run the engine to get used to starting it and running it. After wsrming it up experiment at full throttle with the main needle. If you have a tachometer, get the engine running as fast as possible then open the needle to drop rpm by 300. Then adjust the slow running needle, agsin aiming for the fastest speed then check if it accelerates cleanly. If it hesitates it's too rich if it dies it's too lean. Then stop it, let it cool, and try restarting it. With a cold engine, finger over the carb intake and turn the prop over. Once the fuel has reached the carb, open the throttle fully and turn the prop over by hand for 3 full turns to get the required rich mixture - flick the prop over listening to the noise made by the wet engine. Then apply the glow start and the starter. If you have the correct prime, the engine should start immediately or at lesst show signs of life. Each engine will require different priming to start easily. You need to learn what your engine needs regarding priming but 3 choked turns of the prop is a good start. It may need more though. You don't need your instructor to help you do this.

Well done for persevering. Did you have a go at starting and tuning your engine or did your instructor do that? If he did, did he explain what he did?

Hi Adrian I use a 3rd party telemetry product made by SM Modelbau called a Unisens-E. This is rated up to 280 A current so should be suitable for your use. It is a very small device that fits between the battery and the ESC. It provides real time capture and display on your Tx screen of current draw, voltage, rpm, height and a few other functions. It's greatest use is to provide what is actually happening in the air. The display is real time but there is a function to provide max and min values recorded in flight. You can use it to display capacity remaining in the flight pack. I use an alarm that triggers when I have 900 mAh remaining in the pack. You can, of course, use the output when on the ground. There is another product called UniLog 2 that is slightly larger and incorporates a micro SD card so that every flight has data recorded that you can then download and keep to compare over time. I've not used this as I am more interested in the real time display as well as the max min recorded. With either, the guesswork is removed and you can either get someone to look at the in flight readings or glance down yourself to see what's happening. At Euro 66 for the Unisens-E and Euro 99 for the Unilog 2, they are excellent devices and even if your radio provides onboard sensors, this sensor is both small and light as well as being designed to interface with most of today's radio brands. The radio brands the products work with are specified in the description of them. Here's a photo of the Unisens-E in my Anthem. To give the photo size, those are 4 mm bullets. On the left hand picture, you can see a thin white wire that is soldered to the yellow 3 phase connection and on the RHS you can see the white wire terminating in a plug into the Unisens-E. The white wire gives rpm. The small black wire connects between the Unisens-E on the positive terminal with the negative terminal to give voltage and the current is measured as a clamp meter would as it runs through the red wire that goes through the Unisens-E. There is also a height measuring capability although how it does that I do not know. It tends to zero itself on start up. You can also set a variometer function and get it to alarm at different climb and sink rates. By setting the pack capacity the system will decrement charge from the time you connect the battery and start using it. Again, you can set alarms for charge remaining without needing to look at the output. There is a 4 wire plug to carry the usual signal, positive and negative and a second signal. The second signal wire provides the max/min function and needs to be plugged into a spare channel in the Rx. I find the Unisens-E invaluable when checking over a new model setup. Thereafter, the max height readout is useful to let me know if I stay in or went out of the box, and the capacity alarm is helpful on a high wind day when more capacity is used up. Generally, an 8 min schedule flight consumes about 3,000 mAh. On a windy day this can go up by 500-800 mAh so as I use 4,800 mAh packs it is close to setting off the alarm which is set for 900 mAh remaining. Hope that helps with your deliberations.