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Stability has (possibly) a few meanings. Aerodynamically (we need an aerodynamicist here) I don't believe the characteristics of the airfoil, in terms of CofP movement etc etc, will vary by scale or reynolds. I could be wrong. However - taper, wing loading, tailplane size, neither factor in the airfoil parameters. At an airframe level, a tapered wing will exhibit more tip stall at lower scale due to behaviour at lower reynolds. I guess that could be 'stability'. How the tip stall problem is countered is a different question I guess.

For low use or hobby cars or cars on a SORN a maintenance / trickle charger is a good investment. Dont forget nealy all cars from the 80s onwards had a an alarm or built in computer that draws a few mah that will drian and damage a car battery after a few weeks . I have a trickle maintenance charger in my hobby car , costs around £20 uses hardly any power and keeps car battery healthy and ready to go and far cheaper than replacing battery.

Perry pumps IMO: - good but quite pricey by comparison to the extra tank - quite small and easy to retrofit, especially in a tight install where a tank won't fit - not every carburetor will be 100% happy with a pump, although most twin needle can be made to work acceptably well * * When I converted a pump engine (with a flaky pump) to regular operation, the main difference in parts was that the carb barrel was different, which had the effect of altering the mid-range running characteristics. Without the different barrel, the midrange would have been lean without the pump.

Fantastic, appreciate the advice. Mine has two 3s 2200s up front and balances around 90mm from F2, total weight is only just over 4lbs so didn't know whether to leave as is for the maiden or add weight up front.

It is correct lads, that low mileage can badly effect the battery. Many companies recommend 4000 miles per year minimum to maintain a battery. If you do have to run a low mileage regime, the battery needs topping up. To achieve a good input from a car alternator typically occurs around 40mph, and a minimum top up should be around 30 minutes, Therefore it you find the battery lacking, nip out onto the dual carriageway for 30 minutes or a spin down the motorway for 15 minutes.

Drawing quotes 70mm, but its very tolerant and to save adding lead only to then remove it I maiden mine at 78mm and it was fine (might remove some more when I get around to finishing the model! Ron has mentioned hos is as far back as 100mm (did say its very tolerant !) and the point there IMO is the elevator becomes progressively more effective as the C of G goes back so don't fly with massive elevator throws if the C of G is a long way back from 70mm conversely don't have little travel and C of G at 70mm. I put a little up on my elevator...that I then had to remove, IMO set flat. PS one of the advantages of a more rearward C of G is it will take off and land slower, handy for the dolly launch.

What was the general consensus on C of G for these models, I remember seeing some discussion around it but can't find it now..so may related threads! Thanks

I know exactly where you are coming from. But at least you are always striving for perfection. Reminds me of when I was a young child I used to love colouring books. Once the pencil or felt pen went over the lines more than a couple of time I would abandon that page and move to another fresh page with the intention of making it perfect. Usually the book would be filled with unfinished pages 🤔

In 2021 I bought a new Skoda Octavia 2ltr automatic, it was pre registered in March of that year, I bought it in the August and it had 6miles on the clock. I used it a lot initially doing 2 long journeys. Then back in my normal routine driving to the field which is 1mile away and the supermarket which is 2.5 miles. The start stop ceased to work and other related functions like the door lock sensors also stopped working. A message came up to run the car to charge the battery which I did, things improved but a few days later back to square one. I took it back to the dealer who said I was not doing enough miles. They took it in, said I had to leave it overnight, next day all was fine, two days later no stop start. Despite numerous complaints they suggested I buy a charge to charge it overnight. I did not and lived with the situation as I didn't do many miles. However 2 months before the warranty expired the battery died whilst in the supermarket. I got a jump start which got me home. Ringing Skoda help an engineer came out with a new battery and ran a diagnostic test on the battery which showed the history and it had been under capacity from when I took delivery of the car. He fitted the new battery and programed it to the car. Since then no more trouble and I still do the low mileage.

There are as many stories [ old wife's tales] about car and other vehicle battery's as there are about nicads, nimh, and lipo's. Many on line of how to revive dead ones, just don't, they do not work and some are dangerous. Last year I was on my way to the flying field when the battery warning light came on in my cars dash. Shortly after the power steering shut down and then engine went into limp mode but still ran. Tests showed the battery was low volts. Turned out alternator had quit Now in an older vehicle once the alternator stops working the charge warning light came on and gave plenty of warning for you that it would sometime ahead run out of charge. In more recent cars the batt warning light controlled by the ecu only comes on when the volts get low giving little warning. I now have a volt meter that plugs into the car power socket and can keep an eye on state of charge in the battery [engine off] and if charging [engine on].

I am guessing you mean Tayna batteries and auto correct has changed it. They have a very good reputation.

In this case, we’re looking at a solution for the ground handling difficulties which seem to plague some models - and the Hurricane in particular. There’s no magic about a CofG position marked on a plan - we rarely know whether the designer has marked it there as a result of practical testing, calculation or even guesswork! Then we also don’t know whether it’s been chosen by personal preference or with safety in mind. In fact, if the plan shows a CofG range rather than a single point, I’d have more confidence in the designer’s aerodynamics competence. In this case, I’m carefully conducting a test of combining more rearward positions with reducing elevator movement based on Jon Harper’s experience with similar warbird models. This may not correspond with full size movements but perhaps scale effects e.g. Reynolds Number, start to become significant on control effectiveness with models of 1/6 or smaller scale? I have also provided a “taxi” switch (non latching) which gives a higher rate for taxying and initial stages of the take-off run. This carries over from pre-experiment times.

My build pipeline is usually pretty stable for the rolling 3 to 6 months going forward. Impulses and changes are usually slotted in behind this. There are, of course, the inevitable little flying incidents which precipitate some queue jumping intervention, but those have not been an issue so far this year🤞 However, I have offered to cover a friend's model in the next couple weeks, which I can slot in during the evening, otherwise he will never finish and fly it. I also just volunteered to repair and service a new club member's Kamco Kadet trainer, unflown for 15 years. Including its gummed up and seized up OS30 rc engine. So my planned build pipeline is a little off course right now and about a week behind.

A big difference between a scale aircraft with a higher wing loading than non scale lightly loaded aircraft. Scale or semi - scale aircraft normally have smaller tail surfaces and tapered wings which also has a bearing on the stability.

I would have thought that a heavy model would be more stable because it would be less likely to be blown about in turbulent air than a lighter one. Apparently my Barons are heavier than they should be. I'm hoping for a bit of a breeze in la Coupe Des barons in June! 😏 Of course a heavy model with a cg too far to the rear would be a handful!

I thought the issue with the battery in my 2017 Skoda Fabia might be of interest. One evening, a few weeks ago, the alarm in the car suddenly went off as it was parked on our drive. I tried cancelling it with the remote, but it continued for five minutes or so, then stopped, at which point the car went dead. Nothing worked. No central locking. No engine management lights. The following day, however, I found that the battery voltage had dropped so low that my smart charger wouldn't kick in as a temporary fix and neither I or a neighbour had jump leads. Obviously, I needed a new battery. Manufacturers recommend you change them every five years or so. Mine was clearly living on borrowed time. So, having shopped around online, I found Halfords and EuroCarParts had the Exide 027 battery I needed for around £145, with Halfords wanting £27 to fit it. But then I found a battery specialist in North Wales called Taymar who were selling it for £89.99 including next day delivery. I was initially suspicious about the price difference, but I went ahead and ordered it anyway. I have to say their service, packaging and communication was excellent. In less than ten minutesI had fitted the new battery and I was back in business. Now, here's the bit that caused me some head scratching, my car has stop start capability and there seems to be some misinformation on line about battery coding when it comes to cars with this feature. I don't pretend to fully understand it but some cars with stop start, need to be told that a new battery has been fitted via a code and an OBD-II reader. However, as I subsequently found out, this only applies to cars with an AGM ( absorbent glass mat) type battery, not as in my case, an EFB battery. In fact EFB batteries don't have a code on them because it's not needed. You live and learn.

Take 2 airframes, 1 heavy and 1 light and you will see the difference in stability. I once did a kit review for David Boddington and when I had issues with the flight performance of the aircraft which was heavy and then compounded by our thinner air in Johannesburg, David said I should move the CG forward of the recommended position and it did help the flight characteristics. I have done this ever since and had good results. CG is also a personal preference as some pilots do like a twitchy airframe and others do not. Stability at low speed quickly shows if the CG is correct.

As far as I can recall, in the 10-30cc bracket, we only have two 'effectively' silenced petrol engines in the club. Both have pipes that cost £150 or so. I was once told that to effectively silence a petrol engine, you'll spend as much on noise reduction as on the engine itself....... probably a slight exaggeration! Personally, I'd wait until the intended home for an engine is determined before shelling out on a solution that may be unsuitable e.g. a nice shiny pipe may be ok on a sports model, but offend you on a scale model....

Sorry but I don't understand why that should be....... I'm not saying you're wrong, but I don't see the reason why that should be...

This could give you some ideas https://youtu.be/8klnH1vLHbc?si=6Sv_VKACB7nI2cDR

Every time I see a nice Corsair, I think "I need one of those"....... (Sadly the twist n turn retracts always put me off. Maybe one for when I've more Warbird experience).

The heavier the airframe the less stable the aircraft will be so a more forward CG will be required. Always hard to put more weight in a heavy airframe. Elevator movement is critical as too much can result in a snap roll. EXPO can work against you on a test flight if the trims are out and you need to say up before trimming. I have always found it best to fly the aircraft to see how it handles as some aircraft can handle excesses better than others. Tomorrow we will be flying a 1/4 scale S6 that the builder never flew as he thought it was too heavy and would not fly. It flew very well when Byron test flew it and the original builder will be with us to see how well it actually flies.