Martin Harris - Moderator

Spoilers and airbrakes are actually quite different so make sure you're searching for the right thing. Spoilers normally lie flat on the wing surface and were fitted to many earlier gliders. They work by spoiling that part of the wings lift but only contribute a limited amount of drag. Airbrakes are blades which come out of the wings vertically, both spoiling lift and contributing significant drag. They can be provided on the top surface only, or far more effectively, top and bottom surface with deliberate air leakage through the housing. Learning to sideslip on the approach was a very useful skill on vintage gliders! As the T31M was a conversion, essentially just sawing off the nose section to mount the engine and adding an undercarriage, I would think you can safely assume that the spoilers would be in the same place as the original glider. I've had success with using ailerons mixed to deflect upwards on several non-braked or flapped model gliders - including a 4 metre Fly-Fly Discus. Not scale of course but fairly unnoticeable except by the pickiest purist...

Dunno. 11 years on, the original battery (more correctly, cell) in my DS16 is still performing well.

Really? I’d be quite happy to be asked to pass either side - this reflects a choice whereas both is an instruction!

Well, I’ve just maidened mine and I don’t recognise your description, Futura. I didn’t fit the undercarriage though so perhaps it makes a significant difference? I found it very responsive on the recommended first flight high rates and switched to low where it was still quite lively. It got away steadily and as soon as the speed built up performance was excellent with big loops, both positive and negative coupled with benign high alpha flying. This was with a new GNB 2600 4S (120C claimed) - perhaps your battery is past its best? I flew for 6 minutes but will probably standardise on 5 minutes to allow a good margin as I landed with 14% remaining.

Timing is self regulating by the amount of heating of the element. As loading with increasing revs increases, the element (a catalyst) reacts with the methanol more readily, effectively advancing the point of ignition. If an engine such as the magneto equipped Zenoahs has no method of varying the timing, you have to compromise either to easy starting or maximum power. Damage mostly occurs when timing is over advanced, causing detonation, which causes the damage to piston crowns etc. Normal engine running is a controlled burn - not an explosion, which detonation is akin to.

Like all Hurricanes, a pain on the runway but if you can keep the spinner off the grass then once airborne it should be a delight to fly. I can’t tell you the weight offhand but with air retracts (now electric) and a 90FS it is no lightweight although the builder (I bought it when it was already quite elderly at the Watford Swapmeet in 2003) had taken the trouble to fabricate a built up tailplane. It still has a large slug of lead in the nose though. As far as I can recall, I went with the plan CofG.

Handy if you’ve got a short sighted hamster. I often wondered about turning up with a couple of large lorries and putting the statement “everything for a Pound” on the window of a well known high street store to the test! I’ve also never quite worked out how to comply with road signs before bollards/islands directing you to pass on both sides…

Absolutely - that’s why I qualified the design aspect. Manufacturers don’t always get it right - I believe at least one had to replace a number of badly designed throttle barrels some years ago where the scroll was wrong and made them horrible to try to tune in mid range.

I use that as an initial indication that the idle mixture is too rich. Unless massively rich you’ll probably get away with it but a properly designed carb will not give any obvious drop and should work reliably over its whole range if leaned correctly.

Never a truer word. An ASP 180FS that I had in a Miles Atwood Special left barely a trace of oil on the airframe - just a faint (and very scale looking) sooty mark near the exhaust outlet. The same engine, running the same fuel, in a Seagull Yak 54 left the underside like the aftermath of the Torrey Canyon (younger members might prefer to relate to the Exxon Valdez).

+1 for something like an 18 or 21W lamp - indicator or brake light filament from a failed rear/brake light one.

JD8's method is easier for a lamp (bulbs are what you plant in the garden, as our storemen at work drummed into me!) with spade connectors - you could solder to them or use a dedicated 3 wire headlight connector from a scrapyard (or Halfords!) Remember that if you use a halogen headlight lamp, it needs to be kept scrupulously clean (use meths or alcohol) and not handled by the glass or it will fail quickly. It will also get VERY hot.

Very. Tin the wires and a spot on the casing, hold the wires onto the terminal and tinned spot and apply the soldering iron.

We're lucky to be at the top of a chalk hill so our field drains pretty quickly although the downside is we sometimes find the clouds forming at ground level. Last Thursday there were actual puddles on the field and the drag through our well trimmed grass was enough for my Vampire to reach terminal velocity before flying speed was reached but by Saturday it had dried enough to reach flying speed rather more easily...although the "slight" increase in wind speed meant that the ground roll was negligible!

The concern would be voltage depression with several servos under load or stalled rather than average current draw. However, if the maker's data is to be believed, the plugs and wiring are likely to be the limiting factors.

That rate would be for the purposes of standardised testing rather than a maximum discharge rate. The voltage will drop as the discharge rate increases and that is the critical factor. The site linked shows a maximum discharge capability of 7.5A - in other terms, 3C.

Years ago, the BMFA News published a simple to use nomograph which I’ve used successfully on a number of occasions. I don’t know if anyone has an electronic copy? The published CofG should really be a range of positions within which the handling will be acceptable. Where a point is marked on a plan will be the designer’s best guess at a good starting point (or in the case of some ARTFs an arbitrary guess/error!). The position of an acceptable CofG depends on many factors - primarily the mean chord (this takes into account wing taper and sweep), the effectiveness of the tail (area and moment arm) and personal taste so there’s no “one fits all” solution although it will often be within the 25-33% range on a trainer/sport/scale type platform.

I experienced that a little after 9am. I’ll flag it to the IT team. First time for weeks though.

Whatever solution you end up with, I would recommend flying a few sorties and then measuring the remaining capacity to give an accurate idea of your maximum safe duration.

I think it depends on the age of the unit. Is it the earlier version that takes higher than 6V?

I've heard reports of poor performance from capacitor based electronic ignition running on AA cells as they have insufficient capability of delivering energy fast enough. Therefore, whatever the power draw while running, I wouldn't use AA - especially as high capacity versions have relatively high internal resistance which limits power delivery. If your unit is happy at slightly higher voltage, have you considered LiFe? P.S. I've found the following RCXEL instructions. Typical consumption appears to be 650mA so I'd aim at a minimum of 1200mAh so that you'll use less than half the claimed capacity. NOTE THE ADVICE TO USE A REGULATOR OR (MY PREFERENCE) SILICON DIODE TO DROP THE VOLTAGE IF YOU USE LiFe: 2.) Selecting a Power Source I.) 4.8 and 6v volt NiCd/NiMh Packs: The Rcexl Ignition ver 2.0 is rated 4.8 to 6v a max of 7 volts. A 4 cell 4.8v pack and 5 cell 6v pack with a minimum of 800 mAh is fine and creates a hot spark. The Rcexl ignition ver 2.0 runs most efficiently on 4 cell packs and 5 cell 6v pack . Do not use an old Pack!! If it’s not good enough for your receiver, it’s not good enough for your ignition.. If Use 4.8v pack the engines not highest rotational speed, Also use 6V pack II) 6.4 Volt Li-Fe(A123) Packs 2cell Li-Fe(A123) The Volts Max of 7.2 volts. Nominal 6.6 Volts, use a voltage regulator. Or connects one IN4007 diode to fall voltage the use. If engines not highest rotational speed, Also may directly use III.) 7.4+ Volt Li-Poly Packs.: We have found that 2cell Li-Poly Packs at peak charge can be as high as 8 +v. If you are going to use a 2 cell Li-Poly Packs, you must use a voltage regulator. Or Serially connects two IN4007 diode to fall voltage the use The Rcexl ignition runs more efficiently on about 4.8-6Volts and will draw more current at around 8+v, as well as operate at a higher temperature. You also have a higher chance of RFI interference. In brief in can satisfy under the engine highest rotational speed touse the quite low voltage as far as possible Once again, do not use an old pack to power your ignition!

It certainly looks the part. The one thing that’s bugging me is the “optional weight reduction” in the piston - how on earth did they advise machining it?

A common mistake with the OS style 2 stroke silencers is to assume that the rear nut secures the rear section. It’s a lock nut which should only be tightened AFTER the through bolt has been properly tightened. I suspect that this is the cause of lost silencer parts…certainly a common reason for leakage.

They will be recycled or reused for less demanding applications.

I'm intending doing the cycling in flight but keeping a close eye on this pack! The supplier suggested that the imbalance was acceptable but I'm not at all convinced...