Jim Burton 1

Well, you've posted under discussion of the ARC Ready 2 PLANS, but you are asking to buy Thunder Tiger PLANES. If this is a typo, then no, I do not have any plans, but I do have a plane for sale! Let me know.

Yes Stephen, my thoughts exactly: I had been told by several modelers as well as the molecular chemists at Model Technics that 'fiddling' with the low end mix screw would likely be unecessary/inadvisable on such a modern engine, as it would have been optimised at the hi-tech factory. Therefore I've left it at the factory setting. It must have had 5 or 6 complete tanks of fuel: I certainly have the patience to give it another couple of tanks, if you think this would help it settle. And only then tweak the low-end adjuster.   Ken, that's good advice. I can see now from the exploded view: how the two needles oppose each other in the barrel K, and how the main mix needle C reduces the size of the largest air intake hole, whereas the slow mix needle J does the same for the lesser sized hole. As they are both in the same chamber K, like you say, one will affect the other, so some 'juggling' will be required.  

Thanks Stuey - it's mounted sideways BTW - I've no idea what the 'loading up' effect you mention means. You might explain if you have time. Anyway, anything smooth and reliable sub3k rpm should be fine you reckon, so that's what I'll aim for.   And Ken, I'm assuming that the bottom end will need leaning in my case, if we have read the symptoms aright, so that will affect the top mixture, er, how? Logic says the top end will become overlean if it is so adjusted at the bottom end, am I right in this assumption, i.e. that leaning the bottom will then involve counter-richening the top?

Thanks guys,   I'll go back to the field bench and put your tips into practice.   To sum up: a) fuel and plug OK; b)10k rpm tops is normal; c) 3 turns out is way too rich - aim for +-2 d) adjust (lean-in) WOT mix for max revs - less a couple of safety-richening clicks. e) when engine fully warm go to idle and adjust the low mix screw clockwise by 1/8th turn until a smooth safe idle is attained.   Question - I'm guessing that my dream of a smoothly-purring 2.2k idle is not going to happen and so - what realistic idle revs should I be happy to fly with, to bring in to a safe landing a 3.3kg high wing trainer (Ready 2)?

TT say the rev range for this (new, unflown, but broke-in) engine should be 2.2k rpm to 13k rpm. I've measured the revs using the break-in size prop 11x5 and also a scale 12 incher: apart from the big prop running a tad slower, there is little discernable difference at the low end - the motor coughs and dies below 4.5k rpm. And flat out is a bare 10k with either. Understandably, I'm not going to fly the plane like that   Using the 'pinch test' as a guide, I'm set at 3 turns out on the mix needle.   I'm using the glow plug TT provided with the engine - the recommended TT Redline RF 9776. The fuel recommended by TT is "20% oil mix and 10-15% nitro". The guys at Model Technics fell about when I showed them this and said their ubiquitous Contest 10 would be just fine. I wonder...   Word on the field, as guys formed a line to my test bench, was 'get a hotter plug' and the hotter plug most often mentioned was Enya no3. Most model sites describe Enya 3 as a 'standard' heat, however Enya engines.com themselves call it HOT. http://www.enya-engine.com/plug_E.html   I've ordered one anyhow. D'you reckon this will do the trick, or is a better route to stay with the TT plug and source a 20% oil blend fuel?Edited By Jim Burton 1 on 24/10/2011 19:39:34

Yes, I think a trip to the Modelling Shop to inspect the spinner design rather than 'buying blind' on the internet might be safer - I could then match backplate to prop.   TT recommendation for props for the 54 are shown below - I'm running in on the 11x5, I have a couple of 11x6s and the 12x7 is there for comparison if I need it: 'scale' as described = slow and steady I assume, and with my piloting skills that will be just fine by me. Thanks to all for humouring my 'paranoia' - or 'pursuit of wisdom and truth' as I prefer to term it!

Yeah, you're both right - the 'fault' if we are going to apportion blame, does not lie with the APC design, but in the design of my 45mm spinner backplate: yours, Martin, has just what is missing from mine - a serrated area large enough to match the position of the outer prop ring. And Lee, absolutely - the drive washer on the engine has grip all over its surface so is ideal for total contact area with prop back rings.   Could I ask you Martin, the manufacturer of the spinner and where it was bought? I ask because the various suppliers (retailers) sites that I have checked just show a shiny photo of the assembled spinner and do not show the inside backplate view: so if I bought a larger 50mm one for my APC 12x7 I might still end up with the same problem.

Well, as a footnote to this lengthy thread, I am happy to report that the Great Planes spinner adapter kit arrived this morning and does exactly 'what it says on the tin'. Directly replacing the TT nut and locknut and with a threaded nose ready to receive the spinner nut, it all fits together like a dream. Job done.   With the return of decent sunshine, I might even be able to get some flying in at last   Once more, thanks to all of you for your thoughtful, patient, helpful advice.

Thank you Martin for contacting APC. Their response about weight saving seems good 'best practice' for flying machines and sort of explains the 'empty area' though not the purpose of the designed indentation of the centre ring vs the outer ring.   However, they and you might like to view the backplate of a typical aluminium spinner. "Exactly the same" as PB uses, for example, and doubtless thousands of other flyers worldwide. What do we see on this photo? (excuse the paint overspray, I've been doing something else!!). What we see is that, even allowing for lens foreshortening denying us true perspective on this quick hand-held shot, the 'grip that is most effective' that APC speak of, i.e. the outer ring of the prop back, is relatively ineffective, as all the 'grippy' serrations on the ali spinner backplate are confined to an area surrounding the small brass insert. And what we might call the inherently 'slippy' contact area (no serration) is getting all of the important contact portion of the outer ring - that which APC are hoping/trusting will deliver the 'grunt'.   Interesting that APC did not comment on the reason for the 'indented' relationship of the inner and outer circles. I reckon I'm right - the inner circle is indented to 'pull' more pressure onto the outer circle, which as APC confirm, is the 'business end' of the contact area.   Clearly on this type of ali spinner backplate, the prop design defeats itself. One day, perhaps, prop manufacturers might make their own spinners, although plastics and aluminium in the same factory are unlikely to be friends.    

John, thanks for that - I'm guessing you're not a UK resident, as Googling 'Roket powder' gets me into Guy Fawkes territory and possibly a visit from the heavy squad .   That apart - my first reaction is, it's a great idea - I've looked at the back of APC props (a lot, recently ) and have noticed that the more 'eye-bulging' torque I apply to the prop nut, the deeper the footprint on the back of the APC prop when removed for inspection. This would be on a trial install, without the spinner backplate, just directly onto the crankshaft faceplate (serrated all over)and there's a clear impression on all the rear prop surfaces that touch. Nothing on the 50% empty areas though! Are APC missing a trick here, or is there a reason for the 'missing matter'?   As you rightly state, there is a relatively small area of direct metal-to-plastic grip - and when I substitute the spinner backplate, the only serrated area that contacts the APC is the small brass centre 11mm portion.   However, APC are not stupid or careless with their designs - there must be a reason why the rear centre section is recessed deeper than the rear outer ring. I'm guessing this is so that the 'power' of the nut torque on the centre part 'pulls in' the centre of the prop until the outer ring is flush, i.e. the 'recess' is drawn level by spanner application on prop nut. A sort of controlled deformation. I'm guessing APC would have given this the once-over in wind tunnel smoke tests. And found it to be good. Indeed, depend on it happening in most circumstances - unless, of course, the 'empty areas' were 'filled in' by a non yielding cyano/roket mix. More grip? For sure. Worry beads out on the 'controlled deformation' expected by nut pressure vs outer ring surface geometry though.   What would happen if you were to 'flatten off' the whole backside with Roket and cyano mix is anybody's guess - would it alter, for example the dynamic properties, indeed the pitch of the prop which was designed to have this extra tensile stress coming from the drawing in of the the centre detent until it matched the outer ring (became parallel viewed from the side).   Clearly APC produce this design by the million - there must be a reason why the centre is recessed, and I don't feel inclined to mess with it, despite the undeniable allure of having a flat surface three times the area for back grip.   Others, as is so often on this forum, may disagree.

Thanks again Guys.   I might be over-cautious here but I have this day ordered from RC World what looks like a bargain solution (compared to the the JE tenner plus job).   A spinner adapter kit comprising 1/4" UNF Long. Supplied complete with shaped nut and washer and where applicable, an aluminium sleeve is also included. It's halfway down this page if'n you're interested in taking a deko. http://www.rcworld.co.uk/acatalog/Spinner_Adaptors.html   Looks as though it completely replaces the TT nuts and includes the drilled adapter for the spinner to be attached.   So I shall hope to rest easy once this is in situ - not having had your wealth of experience in distinguishing between what might happen or what seems highly unlikely, I'm going to have to go for the 'belt and braces' approach - for four quid I'm going to be a happy man, and not have that horrible 'what if?' feeling gnawing away all the time the engine is running.

Pete B, If you just click 'Page' (top right in your browser, if it's Internet Explorer) and Zoom to 125% the forum will fill the screen and the 'grey bars' will be banished forever. Edited By Jim Burton 1 on 12/09/2011 18:50:32

BEB, PB and Steve. Thanks for your thoughts. Although JustEngines locknut solution looks expensive at a tenner plus PnP, if it is exactly the precise size for the TT54 crankshaft and assembled spinner hardware, I might have to give it a go.   Steve's highlighting of Martin's previous caution focuses on just the situation in which I find myself. The spinner nut is indeed chrome plated brass, and was relatively easy to drill out to the size of the official TT lock-nut recess. A little hacksawing to shorten the overall length and the spinner fits precisely.   Why my unease? When screwing on my 'remanufactured' spinner locknut, it was apparent that the 'give' of the brass was such that it was scraping noisily (squeak/groan noise) as I tightened it. I'll bet when I remove it to mount the engine in the plane, there will be brass shavings apparent. Further, because by thinning down the 'walls' of the brass nut I must inherently have weakened it, I can visualise it splitting under stress and then where would we be? Spinner and chunks of brass randomly scattered at high velocity like some miniature warzone. Not for me - safe, responsible flying does not include flying a known potential hazard of my own making.

Have to agree with most of you Guys.   This forum is consintent (deliberate missspeling where's the spellchecker wen yuo knead it?) full of informed, non-sarky advice, and equally full of real practical dirty-fingernail info from active flyers/builders/theorists. The fact that the forum software is a bit creaky is ok by me. Spell check? I refuse to believe that the informed science-savvy forum members on evidence here cannot spell!? Or care - if they are rattling off a 10 para reply to some comment that needs correcting or informing, for the benefit of all.   When we're shouting helpful advice on the field over a screaming 2-stroke, we don't bother with the odd split infinitive, now do we? That's a retorical question, by the way, but neither I, nor you care.   This remains the most civilised place I visit on a daily basis, and puts our poor broken society to shame.    

Prepare your post in Word if you must, then ‘Save As’ and choose ‘Plain Text’ (.txt). Save it in My Documents or somewhere you can quickly find it. Close Word. Locate the .txt file, double click (it will open in Notepad), Ctrl A (select all), Ctrl C (copy to clipboard), click in your empty forum post area - Ctrl V (paste). Simples! (But not as Simples as writing the post in Notepad in the first place!!)

Peter, your thoughts have made for interesting reading, whether slightly off-topic or not. I for one have enjoyed hearing of your extensive experiences in the field and in the shed! However, this thread is getting quite lengthy, and I don't know if I should start a new one, as my original 'prop spinning off' problem is now completely sorted thanks to you and your generous-with-their-time colleagues.Two 12mm spanners now have permanent residence in my field box!   In the absence of any intervention from forum-master, I shall continue with this thread as it follows directly on. Is it not true that in modelling, as in so many other aspect of life, y'solve one problem only to reveal another. Here goes.   BEB has opined a liking for aluminium spinners and Steve threw this into the pot. (I've inserted my own photos as illustration... Steve said "Like many I prefer the aluminium spinners & these usually have some form of adaptor nut that screws onto the end of the crankshaft. I have yet to see a 4 stroke crankshaft that is long enough to accomodate the spinner backplate, prop, prop washer, retaining nut & lock nut" & leave enough thread for the adaptor so something has to be left off. For my own models I leave off the lock nut & place a plain washer between the retaining nut & the threaded adaptor to protect the tapered section where the locknut would fit.   So now I am effectively using the spinner adaptor as a locknut. However it doesn't have the compressible "splined" feature of the standard locknut which leads me to believe that this method is less good than the "approved" factory version......it does retain the propellor in most situations however. "   Hmm, so the choice is 1) an 'official double locknut and no spinner or 2) no locknut but a spinner held on with the spinner adapter nut replacing the locknut.   I'm not thrilled with the latter configuration, having spent last week avoiding it.   So what I now have is a succesfully locked prop, sans spinner, which forces me to apply the starter to the naked propeller, centreing it by eye and, I have observed, leaving a considerable residue of rubber unevenly stuck to the front face of my otherwise carefully balanced prop. Not good.   I have a proposed 'fix' that I would like to run by you.   The spinner adapter nut could, perhaps. be 'drilled out' to the same radius and depth as the recess in the upper (female) TT locknut, which could then be discarded. The space thus saved would then provide the best of both worlds: a locked prop and an ali spinner.   I wonder if those of you with metalworking experience might like to give me some feedback on this idea.

As a rider on the male-on-the-bottom, female-on-top debate - the makers of the famous industrial HardLock nuts, very similar in design to the TT jobbys and used commercially worldwide on Wind Farm props, railway bridges etc., pretty much confirm this configuration as shown on these two excerpts from their pdf diagrams, although it is hard to see why either way would not be acceptable just as PB postulates above, especially as Hardlock nuts can apparently be used either seated to a surface or free-standing on a screwed shaft.         So...Glasshopper shall try both ways. (With safety goggles and gardening gloves.)