Jonathan M

Yes the latest DX7 does, but you can either imhibit it or quieten the volume. You can also if you want select exactly what it says for any condition.

Posted by kc on 12/09/2016 10:34:28: Probably the book that best answers David's original enquiry is this one by Andy Lennon free to download here But it goes into things in depth and is more difficult to read than Peter Millers book on design ( in my view) Thank you kc. Waiting for my second-hand copy of Miller's to arrive in the post, I've just scanned through the Lennon download. This is a fantastic resource, perfect for reference (in as much detail as one wants or probably needs) of specific topics. But the great challenge (in general and not directing this as Lennon's own personal designs) is to couple such principles of aeronautical engineering with aesthetics, attractiveness, style. The iconic full-size example is Mitchell's Spitfire, and Chris Foss has in my opinion (and that of the RC marketplace) achieved this with his Wot series.

Thanks folks! I'll do as I'm told (but don't tell the Missus!) and fit the 10oz tank forward.

Posted by Richard Wood on 12/09/2016 08:11:36: Hi Jon, Your 3S, 3300mAH battery is really too small to get good performance & duration from a Wot4 IMHO. You could consider the Uno-Wot. Not as aerobatic as the Wot4 but flies well with the reduced dihedral as detailed in the instructions. It should suit your electric set up very well.   Thanks Richard, the Uno-Wot actually seems like a very good option. As befits a trainer design, it'll likely be more floaty (wing loading 15oz/sqft) than the Wot 4 (20oz.sqft), but the idea is for a gentler flying experience on calmer days. Plus it'll make a good trainer for when my son is old enough to concentrate for long enough! Edited By Jonathan M on 12/09/2016 09:29:19

I'm planning the installation of fuel-tank, batteries and RC gear in my ARTF Acro Wot, and have a question about tank size and position. Running an ASP 70 FS, what size tank to fit? I have both 10oz and 12oz available. What sort of flight times are likely with these (intermediate sports flying), and is the bigger tank overkill? Given the progressive consumption of fuel weight during a flight, is there any rationale for mounting the fuel tank further aft (ie towards the LE of the wing) so that trim isn't effected so much? Why are tanks always mounted as close to the engine as possible - surely with exhaust pressure into the tank some distance is acceptable? From reading the very long thread on the Acro Wot ARTF, I'm aware that some planes come out the box tail-heavy. I don't yet know how mine will pan out, but if I can move the tank back a bit, then there's space to establish the correct CG by playing with battery poition and size/weight in the forward compartment. Cheers Jon

I'm vaguely interested in the subject, and a quick trawl reveals (in rough order of novice-ness): 'Model Aeroplane Building: Sketch by Sketch' - by Peter Holland 'Designing Model Aircraft' - by Peter Miller ‘RCadvisor's Model Airplane Design Made Easy: The Simple Guide to Designing R/C Model Aircraft or Build Your Own Radio Control Flying Model Plane’ - by Carlos Reyes ‘Model Aircraft Aerodynamics’ (5th revised edition) - by Martin Simons ‘Model Planes: Aerofoils and Wings’ - by Martyn Pressnell Although I’m still brushing 40 years of dust off my old aero-modeling skills, and haven’t (yet!) designed a plane of my own, I can’t help thinking that building a few planes – from balsa-based kits and/or from plans or at least downloading and studying free plans for the sort of aircraft you’re interested in – will teach you a huge amount about weaving the construction and design sides together. Standing by to be shot down…

PS Of course I could add roughly a minute to each of the above proposed WOT4 flight times by running batts down further, say to to 25% capacity (thus the existing 3s 3300mAh 4-Max Lipos could give a max of about 7mins with non-extreme sports flying), but past experience of being cavalier with this resulted in shorter battery lives and also a couple of puffed-up units despite never charging at more than 1C.

Posted by Biggles' Elder Brother - Moderator on 14/07/2016 20:47:31: OK lets do this the right way round! With IC you start with the engine - but you don't with electric power. Paradoxically the motor is almost the last thing you select. We start with the weight.. Hope this helps not just in answering your direct question but in terms of equiping you to be able to work it out for yourself in future. Thank you so much for explaining all this! I'm looking to transplant the whole power-train from an E-Flite foam Hurricane into a Wot4 balsa ARTF (I'm happy with electric but really dislike foam, and have little budget left for new power-plant components, batts, etc). So I entered the method explained onto a spreadsheet and ran through the main inputs (excl prop sizes) to find out if it was feasible, then fiddled with some variables to see how these effected performance and flight times (each time leaving everything else the same): E-FLTE foam HURRICANE, as existing: 4.6lbs AUW, 460sqin wing area (roughly similar to the WOT4?). 60A BEC ESC, 25BL outrunner 1000Kv (don't know what the 25BL stands for), 11.75x7 prop. Assume 75W/lb for scale flying, 65% average power, and a safe 35% capacity left in battery. 3s 11.4v 3300mAh 40C Purple Power pack produces a calculated result of 7mins flying time, which tallies exactly with my experience at the patch. WOT4 balsa ARTF, with transplanted electrics: 4.8lbs AUW Same electrical equipment and battery as above (assume the 60A ESC and 1000Kv motor are right?) Same 65% average power and 35% remaining capacity after flight. Assume 100W/lb for full sports flying. Using same existing 3s 11.4v 3300mAh pack indicates a max of only 5 mins flying which is pants. THEN, EITHER - reducing power-to-weight requirements: 5.7 mins at 90W/lb (moderate sports) 6.4 mins at 80W/lb (gentle sports) 7.3 mins at 70W/lb (quiet pottering), which all remains pants! OR - increasing cells/voltage and capacity (allowing for marginal weight increases at each step): 6.4 mins - 14.8v 3300mAh 7.0 mins - 14.8v 3700mAh 8.3 mins - 14.8v 4500mAh, which still isn't great and is beginning to get very expensive! Maybe, instead of pushing this any further, is there a slightly smaller/lighter alternative to the WOT4 that will suit my existing electrics (not foam, ARTF preferably but a kit if need be)? A robust tail-wheel intermediate sports flyer with similar wing-loading and good manners, and capable of the same wide performance window? Thanks, Jon

Thanks Jon for your superb explanations - I'm going to follow your advice to the letter.

Going electric when I started three years ago was a good decision. My local club does both IC and EP, but its rules meant that I could only train with an instructor or A-Cert holder by my side, which wasn't always available. Electric allowed me to find any old field with flat enough ground for takeoffs/landing and get in plenty of flying practice without anyone being bothered. The cost of electric wasn't excessive, nor was the kit required: a mid-size foam aileron trainer, three 2200mAh Li-Po batteries, a checker/balancer, and an inexpensive charger that runs off both mains and a small 12v lead-acid for field charging. Sometimes I just take and fly three batts then go home, but 1C charging takes 40 mins per batt which is fast enough to allow a whole afternoon at the patch - given the time one spends chatting with other members or quietly relaxing or spectating. I got my A-Cert a year ago and moved onto a second-hand foam electric warbird, more powerful than the trainer with three 3300mAh batts giving 7mins flying before I'm down to 40%, which has helped keep up and advance my flying, yet feels fake and unsatisfying. So I'm moving to IC, with a bit more up-front capital expenditure. The electric kit will still be used, especially if I've only got a brief window of time to fly then get home again. Maybe I'll even ditch the foam warbird (the fake bit) and recycle the gubbins to power something like a balsa Wot 4 or similar?

Mmmm... now in a quandary here! While I bow down to the expertise and experience offered, and am tempted by the much shorter run-in process suggested, my instinct is to borrow elements from Jon's advice for the ASP 70 (e.g. pre-oil the tappets and inside the crankcase), but go with the instructions provided by JustEngines (from whom I bought the engine) for a gradual run-in: 1/4 throttle, very rich for 10-12mins, then let cool and check/tighten head and backplate bolts. 1/2 throttle, rich with occasional leaning (say 2min rich, 1min leaner) for 12-15mins, then let cool. 3/4 throttle, rich and leaning as above, then cool. Full throttle, rich and leaning, etc. Full throttle etc as above for several more tanks, gradually leaning the mix until engine is happy at all throttle settings. When cool, check tappets (re-set if necessary) and check/tighten all bolts. (The OS instructions for the FS-30 Surpass already indicate a much shorter process, not dissimilar to Jon's advice.) One other question: why hand-start with a reverse flick rather than normal rotation?

Moving over from electric to IC and have a question about running in my two engines - an ASP 70 FS and an OS FS-30 Surpass. Running-in the ASP 70 appears from the instructions to be a full and lengthy process, using a prop of slightly smaller diameter and pitch than the flying version - and a gallon of fuel - before checking and re-tightening everything. Whereas the OS FS-30 Surpass instructions suggest only a minimal run-in to set the mixture, with no special run-in prop etc. Is this because the OS is smaller, or of different quality of manufacture, or some other reason? Jon

Learnt lots already! Thanks.

Thanks for the welcome. Useful to learn the limitations of nyloc nuts! What about using split washers with regular nuts (with/out thread-lock)? Also, locking nuts with wire or other sophisticated technology only deals with one end of the fastening - surely one would need to lock the head as well?

Hi I returned to the hobby, after the regulation break of 35 years, about three years ago. My interests seem to be split three-ways: RC fixed wing - Started on a RIOT which got me through my A Certificate but which I eventually rolled with a great thud into the turf (boredom was the culprit!). Moved on to a second-hand E-Flite Hurricane with retracts, which is easy fun but this doesn't much like our bumpy, molehilly, and sometimes turbulent patch. So, fed up with anonymous foam, and now determined to move to IC with enough mass to penetrate and ability to work up basic but proper aerobatics, I've just bought an Acro-Wot ARTF version with an ASP 70FS. (Later, I'll make the DB Sport & Scale 48" DH60 Cirrus Moth kit together with an unused OS FS-30 Surpass in my possession.) RC soaring - Been having much fun on gentler days thermal hunting with an Elf 1m DLG, now assembling a 1.5m Blaster 3 for higher launching and more sustained hunting. (Also got a Middle Phase kit with aileron wing for general-purpose slope work, but this is on the back-burner for now.) Indoor scale rubber - Going back to my earliest roots, I recently built a KK Chipmunk from a Vintage Model Company kit, then a KK Auster Arrow from a plan which I entered it in the BMFA Kit Scale category at the Indoor Nats. As if I wasn't already sufficiently time-poor, I'd like to enter something in Peanut Scale and also have a go at CO2 and/or electric... but the standard of making and flying in the Open Classes is quite intimidating!! MY QUESTION relates to mounting IC engines, ie my ASP 70 FS, which appears to have 4mm dia holes: what is the normal method? M4 machine screws with normal nuts plus thread-lock, or nyloc nuts. Or is there some other non-metric category/diameter of screws/bolts one uses with IC engines? Thanks Jon