Jonathan M

No worries Brian, a pleasure that someone can get use of it rather than it just sitting on my shelf!

Spec says 90 two-str or 120 four-str, but you obviously flew the old one happily on the Laser 80... in a scale sort of way. Does a Laser of any given capacity produce demonstrably more power compared to an equivalent from OS, Saito, ASP, etc? I don't know... but have just ordered a Smooth Operator kit, for which I've got a Laser 80 or an ASP 91. I'm guessing the Laser will probably manage, but again the 91 is at the bottom end of the recommended 4-str range of 90-120. Sorry to hear of the Moth's demise. Coincidentally my old (but new at the time) DX7 was responsible for the loss of my 4-str Acrowot and 4s Wot4, both within a couple of weeks! In my case, after getting it back with a new RF board from the service agent then watching it fail to control a slope soarer for several seconds(!), I gave it away for free but with a warning to the recipient. That was 5yrs ago, been happily using FrSky ever since.

Makes sense Andy... the Master Airscrew's shape certainly looks like it was inspired by the Wright Flyer! It is also heavy, and when giving the Irvine 46 a brief test run (hand-flick started quickly) the whole airframe shook! So out came the prop-balancer followed by 20 minutes with some heavy-duty files! Methinks I'll order an APC 12x6 and 12x5 and see which suits the model best in actual flight.

[Picking up on a 10yr old thread... but the principles haven't aged!] I've got a very nicely-running Irvine 46 in a good Irvine Tutor Mk1 I've just acquired for use as a club trainer. The engine came with a Master Airscrew 12x5 which I assume is probably a very appropriate prop for this model's trainer-function?... big enough to give flywheel effect and keep noise down, and not too fast with a relatively fine pitch for low-to-medium speed flying and acceleration/deceleration? By comparison I have an APC 12x6 on the Irvine 53 in my Gangster, which is perfect for that. Also, more generally, is there any difference between MA and APC props? Any reason why folks prefer one or the other?

One thing I've sometimes done when instructing with buddy lead, especially when a trainee is getting a bit over-tense with repeated constant-height circuits and starts stirring the porridge, is to get him to increase throttle to take the model up high but not too far and go crazy for a few seconds with the model - then release the sticks, throttle to 50%, calmly work out the orientation and attitude, then bring the model back into circuit in S&L flight with only those stick movements that are necessary for that. Repeated 2-3 times, it is a great way to teach people how to get themselves out of a mess without a complete panic.

Leccy, I don't disagree with you at all. I was just pointing out that, for those that want to advance their flying skills in a specific area (e.g. fixed-wing aeros, thermal flying, etc) it can be a long and random process of trying this and trying that, working out what advice to take from some, what to reject from others, etc - and often reinforcing bad or unhelpful habits by repeating it over and over again without critical input or ongoing tuition. There was no-one at my old club who was in a position to help me for years, then I became friends with a chap who is both a very skilled flyer and a natural communicator who has taught me loads. The rest was - and very much still is - practice.

Appreciate both those points Robin, thanks. I'll certainly try the switchable rudder to aileron mix!

Yes, I definitely understood and worked out the correct way! 👍 If the ends point down, i.e. on a high wing, then moving their pivot points forwards reduces the downward aileron travel and increases the upwards one. Thanks for the tip on plastic ends! The ends are threaded, and I think I might even have a pair of offset jobbies from my old Middle Phase kit. (That's a model where I dispensed with the single servo and cut pockets for separate wing servos - thus also enabling spoilerons which work a treat to put model assuredly down on lip of hills in higher winds.)

Thanks Brian. This raises another question: assuming a theoretical single lipo of any given capacity, say 5000mAh, what would be the advantage (or disadvantage) of the lipo being 4s instead of 3s?

Chris, I completely and utterly agree! It's amazing that in almost every single sport people get coaching at every single stage from beginning amateur to world-class professional, but we think we can sally off with a basic A Cert and try to teach ourselves to get better! We might with practice become a bit more confident and proficient, but only with periodic input from a skilled instructor (or a lot of hard personal study and discipline) will our skills and ability develop.

Thx chaps for the input. Every model I've ever had has used separate wing servos with diff (and other tweaks to equalise both wings) programmed into the radio, but I don't want to spend too much time on this one... the single old Futable S3003 will do fine! I'll see if I can find in my bits box a suitable circular servo-arm to set up the raked geometry. If not, then I was going to carefully bend the pokey-down ends of the torque rods themselves to rake forwards to achieve the same result... or at least iron out the slight negative diff! Co-ordinated rudder isn't critical of course, but it'd be nice to get the rudder properly set up - the book says 15mm each way, which is very little really especially if taxiing in a stiff wind, so I've increased that to 30mm with a decent amount of expo. Aileron it says 6mm ea way which is about right for a trainer, but I'll set it up with say 7 up and 5 down at 60% rates so can easily increase it at the radio if necessary. Elevator 10mm ea way, but again I'll do 15mm then dial down the rates (and expo) to student levels, etc. Notwithstanding programmable radios, I've always been a fan of getting the mechanicals right - to use the full range of servo rotation for good resolution, with the correct mechanical advantage at the control surface.

I've just picked up a used but very nice Irvine Tutor Mk1 with a lovely Irvine 46 (been through at least two previous owners) for use as a dedicated club trainer, and currently going through everything (rx, servos, linkages, engine/tank stuff, etc) before first test flights. The wing has the usual single servo with torque rods. But these can't be properly perpendicular to the hinge-line as both ailerons have a bit more down than up (i.e. negative differential), so I'm about to bend them back for either (1) completely equal throws, or (2) some positive differential. My question is this: does a trainer actually need any positive diff (and how much?) or should throws be kept equal so a learner has to start to use rudder to co-ordinate turns?

Thanks Nigel, and completely agree with building, or even refurbishing - both extremely satisfying!

I agree with Peter - practice is everything ! The hardest two things I'm (still learning to) do well is thermal soar full-house ships on the one hand, and fly trad B Cert power aeros on the other. Both take an inordinate amount of practice. Being decently into my second half-century means slower processing and reaction times than my younger self. The only two things one can do to mitigate this problem are (1) practice, and (2) more practice. Clearly one also needs to understand things theoretically and fine-tune one's models on the ground (both of which are delightful pastimes in themselves!) but in the air only practice will make any difference.

That's great, an excellent and better looking modification - and helpful too.

👍 replied

I have a copy if you'd like it.

Thanks all - I suspected these would be the issues, but couldn't wrap my mind around the precise consequences. I'll keep the field lipos separate then, it's simpler. Re buying extra flight packs: I prefer the field-charging option as I've got several thermal models with specific lipo sizes for each: 450 in one 2mRES (still in build), 550 in the other 2m, 900 in the 2.5m full-house, and 1300 in the 3.6m full-house (currently deceased). A set of four lipos can be charged in one go on my quad charger, while the field lipo(s) get charged on the Q8 itself from a 240v supply. Some sessions I barely use the basic set of whatever four I'm flying with as there's good thermal activity (and/or I'm on form), other times I do a lot of launching and fewer thermal fights, in which case all four in a set get re-charged at least once per session. (Three launches is the usual max, so a set can do 12 launches before recharging.)

I've got two 3s 3000mAh lipos (new but not great quality for flying and therefore surplus to requirements) which I'd like to wire up in parallel into a single 3s 6000mAh unit to power my ISDT Q8 charger (which I normally only use to field-charge 3s 600-1300mAh lipos for thermal soaring, previously off a single 3s 3300). Is it better to permanently solder the main leads into a single XT60 connector, or use (make up) a double-adaptor for field-use? If permanently soldered to a single main connector, what happens to the two sets of balance-leads for balance-recharging, storage-dis/charging, etc? How does that work?! (Obviously if I use a double adaptor then the two lipos can be re-charged independently.) PS - supplementary question: Would it be better to power the Q8 off a purpose-bought 4s lipo of similar capacity?

You did a fine job on great model - thanks for the brilliant build thread!

Good call Frank, and I also like switches with an integrated charging port.

A 2000mAh 4.8v will be fine for your 6ft Cub. I use a 2000mAh 4.8v Eneloop in my IC Gangster 63 with standard servos. Half a dozen or so 12min flights, call it 1.5hrs all told, which is a lot of big aeros flying over a half day session, uses no more than half the capacity (noting what I put back in when recharging). Even though it's a NiMH rather than a Nicad, I do like to cycle the pack frequently (charge back up after flying, slow discharge to 1.0v per cell, then charge back up again).

Great solution Nigel - and I agree it looks so much better for it too!

Have PM'd you.

Thanks EGB. I'm Oxford but can drive up to an hour say and meet half way if needed. Whereabouts are you? Notwithstanding what I said above about electric, if your Irvine 46 is a good runner and reliable and can start with a hand-flick etc, then I might keep it that way (cheaper than buying a whole electric powertrain and set of 4s lipos!).