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Martin Harris - Moderator

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Posts posted by Martin Harris - Moderator

    Ripmax resonses

    in R/C Retailers / Distributors / Manufacturers

    Posted

    Contrary to one or two posters I've raised a few problems direct with Ripmax and had nothing but satisfactory responses. 
     
    ...even to the extent that they sourced some replacement parts for sub-standard items in a Kyosho kit after they had ceased being their agents.
     
    ...and honoured a "warranty" claim for an (unused) OS engine at least 5 years old with a manufacturing fault, that was bought second hand from a retiring club member.
     
    You may also be interested to know that (at least, according to what I was told by Ripmax) that after being contacted by a customer whose club had identified a specific set of circumstances with the then new 2.4 GHz transmitters leading to an incident that it was their own engineers that identified the ability of the firmware to reset the idetification code to 00000 if the affected units were switched off and on within a timeframe of a few milliseconds either side of half a second after start-up and I'm told that they pressed Futaba for a resolution which they duly implimented with the recall.  This information was given to me freely and openly with a request for reasonable confidence until they could organise a proper notification via the model trade and press.
     
     I must stress that I have no connection with them other than as an ordinary customer but I feel strongly that credit should be given where it's due.
     
    I can't say that I have had the same sort of response from a couple of the other major distributors though...

    Skis anyone?

    in All Things Model Flying

    Posted

    skis
     
    As I used on a fun fly a few years ago.  OK on hard snow but a little small for soft snow. Kept the tails longer than the noses for aerodynamic stability and they worked fine without any return springs etc. Half hour job to knock them up...might make some bigger ones if the snow persists!

    Airsail - Dehavilland Chipmunk Kit

    in Build Blogs and Kit Reviews

    Posted

    Just come across this thread.  I built the RAF version 5 or 6 years ago as the first model buld since I had last flown radio models in the late 70s and don't remember any great problems with the instructions or parts fits.
     
    I did not build particularly lightly  - covered flying surfaces with Humbrol painted Solartex and tissue/doped the fuselage.  Also fitted an onboard glow, sliding canopy and the flaps mod.  Top half of an Action Man and one of Barbie's girly friends (not the lightest of pilots) go along for the ride except when Action Man took a small movie camera up a few times...see http://uk.youtube.com/watch?v=sjJLOqqbVxI or an earlier attempt http://uk.youtube.com/watch?v=F-BzNTwjgko
     
    All this is on an OS52 FS but I usually use considerably less than 1/2 throttle to achieve a scalish take-off.  Scale aerobatics are easily achieved with this engine so the 70 will leave you with a decent reserve of power.
     
    I replaced the wire legs with sprung "oleos" which improves the look of it while taxying (lots of bouncing and shimmying with it as standard).  The importer offered an exhaust adapter which locates the exhaust outlet at around the scale position and encloses the silencer completely within the cowling which I've never regretted investing in. I don't know whether one is still available but if you can get one for the 70 it would be a nice touch.
     
    I use @ 15 degrees of flap (which steadies things a little, possibly by effectively introducing a little washout effect) for take-off and 30 degrees for landing (as per full size) and handling is excellent and predictable in all configurations. One of the earlier postings mentioned scale transit speed for the flaps but as the full size used a direct "handbrake" lever controlled linkage I wouldn't worry about your standard servo.
     
    Good luck with the rest of the build and as long as you've built it without any glaring errors I'm sure yours will fly superbly.
     
    Martin

    Prop Removal Help

    in IC Engines

    Posted

    Before you start stuffing bits of wood anywhere, slipping prop nuts usually respond to holding the prop with one hand, putting a well fitting (preferably ring) spanner on the nut (steady the spanner with a spare finger) and giving the spanner a sharp tap with something reasonably hard and heavy...
     
    This is quite a common problem with cheap hard plastic spinners.

    The dreaded down-wind turn

    in In The Air

    Posted

    Never in the field of Model Flying has so much informed opinion been written by so few!
     
    For years I've battered my head against the "experts" who maintain that models balloon on upwind turns and fall out of the sky on downwind turns due to the effects of windspeed and won't accept that the apparent effects are pilot induced.  Like some of the posters I have had considerable experience in full sized (mostly gliders) and therefore know that airspeed doesn't vary (indicated or otherwise) in turns in (non-turbulent) wind - thermalling would have been much harder work!  Mind you, it was always best to be aware of the temptation to slow the glider on the downwind half of a very low thermalling turn when groudspeed started to become visually significant.
     
    Thank you, lady and gentlemen - I shall refer doubters to this thread in the future...my attempts to explain this subject using analogies such as goldfish being carried down the road in their bowls have not always convinced my doubting audience...

    Pick a plane 2009

    in All Things Model Flying

    Posted

    Barry,
     
    I'm so sorry but perhaps, like me, they've failed to see the attraction!  Mind you, apparently, I'm a heathen because I don't go all weak-kneed and (literally) starry-eyed at the Constellation...
     
    How about a GA aircraft for a change - e.g. a Mooney M20J with retracts?
     
     
    An EDF Harrier would be nice with all the armament etc. hanging off the wings - although I wouldn't expect Tony to implement the thrust vectoring (wouldn't that be nice though!)
     
    ...and I'd be tempted by a largish Sopwith Camel and would enjoy getting it authentically oily!
     

    Tony Nijhuis Mosquito

    in Build Blogs and Kit Reviews

    Posted

    Chris,

    Glad my post has provoked some thought for your build.  I've used very short torque rods (see pic 2) to drive each aileron so there won't be anything visible - best of both worlds?  I'm always a staunch supporter of running separate aileron channels to allow for differential adjustment and extra redundancy - I've never understood people using Y leads!

    If it's any help, my technique for torque rods is to form a groove in the TE of the wing and LE of the aileron up to the hole (with the threaded end of a 2mm rod) to allow the rod to lie exactly along the hinge line - extending a pencil line from the TE to the servo connection bend gives the centre line for the rod and alignment seems to work fine - but with only a very short distance in this set up it should be very easy.  The other thing that helps is remembering to radius the entry hole in the aileron to allow for the bend radius of the rod.  Then everything should be in line and you should be able to achieve a free moving and gap free aileron hinge line...

    When I chose my motors it was as close as I could estimate to the recommended set up from Tony's website but practical testing shows that the model pulls over 500 W and wants to move purposefullly towards the ceiling when held vertical so there is a (un)healthy reserve of power!  A good reason for effective cooling for the ESCs as I intend making intelligent use of the left stick.

    Blackhorse Chipmunk

    in Scale and Semi-Scale kits

    Posted

    Mark,

     I built the Airsail Chippie a few years ago and my one regret was the castoring tailwheel, which is, as you rightly say, as per full size.  However, the full size uses differential braking via the rudder pedals (you partially apply the wheel brake lever which allows drag on the wheels without locking them) which allows you to steer when taxying crosswind and helps in the initial stages of take off.  Although my Chipmunk is a delight to taxi in light winds, in anything more it was a real pain.  I don't know the extent of the problems on this model but I would not recommend free castoring.

    Recently, I locked the tailwheel with a few degrees of controlled self centering movement using rubber stops and it is now a delight even in strong winds.  Perhaps a simple fixed tailwheel would be the answer unless, perhaps, operating from concrete or tarmac?

    I must say that the flying pictures on Clive's original article look superb - very realistic - but what was going on when they designed that cowling!  It looks nothing like the very distinctive deHavilland nose.  I wonder if the Airsail one (or a Carbon Copy relacement) would fit these models and finish them off? I think they're a similar size...

    Engine Backfiring Problem

    in IC Engines

    Posted

    There's a lot of excellent advice in the thread above but if none of it helps you, get someone competent to check your cam timing -  especially if the engine's history is unknown

    Don't be frightened to lean on your spanners when tightening the nuts - correct torque is when you feel your eyes starting to bulge.  You'd need to have the strength of King Kong to strip the threads using standard spanner lengths.  I'm assuming you're not trying to tighten the nuts with a multi-way plug spanner which will not have sufficient leverage.

    Also, be sure to tighten the main nut fully before tightening the lock nut against it with a separate spanner.

    Stripped plug thread

    in IC Engines

    Posted

    The thread is 1/4 UNF but if you can't get it helicoiled you might be able to make a threaded bush from brass (similar expansion rate to aluminium, I believe, which is the reasoning behind ABC engines) if there's sufficient material around the thread to make it practical and lock it by staking with a centre punch.

     Getting it gas-tight will be the only problem but perhaps making it slightly oversized / tapered would help.  Insert it with a shouldered bolt or a bolt and locknut once you have the length / fit about right...

     Not much to lose by trying...

    O.S. 40FS Running

    in IC Engines

    Posted

    The breather is actually very important.  Apart from venting the crankcase pressure, it ensures that oil mist is pulled through the camshaft area to lubricate the valve gear.  Try to use the recommended length of pipe - too long and it won't pull the mist through properly leading to excessive camshaft /follower wear.
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