Alistair Taylor

Spot on Simon Some manufacturers of IC engines )and electric motors come to think of it) put a thin steel thrust washer between the prop driver and crankcase. This reduces the wear you would otherwise get when the aluminium prop driver is pushed against the aluminium crankcase if the engine is run in pusher mode; as is the case with cox babe bee engines, which will generate a grey-black aluminium paste around the crankcase/prop driver until the wear is such that the crankshaft hits the reed valve holder. The higher performance cox tee dees came with a thrust washer I believe which avoided this. AlistairT

Ahem to further murkify the muddy waters... APC do electric props (as in props for electric motors) in both tractor and pusher versions.  You would have thought that this was illogical given that electric motors (both brushed and unkempt) can be reversed (barring twin installations where you might want props that rotated in opposite directions), HOWEVER...APC props all come with a set of spacers that ensure a snug fit on whichever shaft they are fitted on. These spacers fit into a precision machined recess on the REVERSE of the tractor props, but on the FRONT of the pusher props. NB only the recess for the spacer is precision machined, the rest of the hole through the prop is done on a friday at 4pm. Thought you might like to knote. AlistairT

Hiya Bob Sounds like your buzzardly friend was trying to pick up some aerobatics tips If your flying site is next to land that was intensively farmed arable land, that is now being restored/farmed in a more environmentally friendly way (less chemicals, more hedges, patches of set aside round the dges) then you'll probably find that the birds that "appear" are actually returning to the places they used to nest in before farming went all industrial post war (and before R/C went proportional). As I said above - if you have rare birds nesting on or around your flying field, you stand a much better chance of keeping it as a field (as opposed to a carpark/housing estate/shopping arcade) than otherwise. Birds are legally protected, model flying isn't. Of course if you're flying on the Stonehenge Intergalactic spaceport (establised 2 Million BC) then OK, fair point, you got there first. Kick those cheeky birds off immediately AlistairT

Probably best just to head down to the 2 hectare flying site, in your left hand drive car, at 50 KPH, in order to fly your 1.3m wingspan plane, with its 6.5 cubic centimetre motor, at a speed of 10 m/s, 50m above the ground. Probably best just to head down to the 7 acre flying site, in your right hand drive car, at 30mph, in order to fly your 45" wingspan plane, with it's .40 cubic inch engine, at a speed of 23 mph, 30 feet above the ground. Eric - I can't help feeling that you're getting confused between the round amp and round tuit. Round tuit's a very thin on the ground - as you will find if you ask a few modellers whether they've got a round tuit. Ali

Hiya Eric The hook position will dictate what kind of launch you get, and how high your glider ends up at apogee (that'll snare a few model rocketry search engines). The further forward the hook, the flatter the launch, and lower the final height achieved (barring a really decent zoom launch). The further back the hook, the closer to vertical will be the launch angle - basically the glider will pivot around it's CofG until the bungee/line makes a straight line between the anchor stake, CofG and tow hook. However, as you move the hook backwards, the glider will become more unstable in yaw, and may start to diverge from flying straight ahead. So - the optimum position is......found by trial and error. Or you can use up elevator to steepen the launch (best have quick reactions in case you get it wrong - or maybe just use small increments of  trim), weave using rudder on the way up to get more height, and dive - zoom climmb to get a "ping" off the top. I found that launching into wind, the line/parachute would get blown off the towhook without pilot intervention. The "best" launch usually takes several balmy afternoons of silent, relaxed, stress free flying to come even close to (at least that's what I used to tell the missus). AlistairT

Ooh yes please Mr Ashby sir

Hi Michael I'd recommend you check out the following (Brit) manufacturers of electric kits; Westwings Concept models Micron Radio Control Greenairdesigns They all offer some seriously good value kits. AlistairT

Steve, I know exactly what you mean. I've got the most appalling wavy line along the leading edge of one of my models - with balsa showing through in places I use a straight edge, and a single edged razor blade as sold by hardware stores - this ensures a clean cut, but only use the blade for one or two cuts, then put it to one side for balsa, and use another. The films we use (and indeed other man made materials like depron) take the edge off a blade very quickly. Otherwise design the colour scheme to make the ovelap easier - e.g. LE topside and bottomside the same colour - or stick checks on the bottom to make it harder to spot the wavy lines AlistairT

Yes please - I like yellow AlistairT

Hiya RC Boy If your EPP is black, you may have an interesting time trying to see black lines. I would suggest photocopying the plan, cutting out the shapes (in paper) you need, sellotaping (other brands are available yada yada) the plan cutouts onto the EPP, and then cutting through the lines on the plan, into the EPP with a sharp (and long, if the EPP is deep) craft knife/stanley knife/scalpel. Hope this helps. AlistairT

Hiya Alan the servo arms can be easily removed and swapped around with a few twiddles of a screwdriver. It's common practice to chop an arm or arms off servo discs so that the servos will fit in the model without the output arms fouling the sides of the fuselage or the arms of other servos. The different holes in the servo arms give different amounts of lateral (push pull) movement through the pushrods for the same rotational movement of the servo. This can also be achieved through the rates switches, and end-point settings on your TX (if available), although once these are at maximum/mimimum, the only way to further increase/reduce movement is to adjust the linkages The circular disks are handy if you want to drill a hole in between two existing holes (for a very precise degree of movement), or if you want to create a cam, e.g. to push against a button on a camera for in-flight photography, in which case you carve the disk to the requisite shape, and mount the servo so that the disk is straight above the shutter release (Shutter release! I'm really showing my age). NBs  - Servos buzzing when the control stick is stationery (in whatever position it's in) means a binding control, higher current draw, and potentially failure - sort it!  - Clevises will foul the other arms of the servo disk, and the mounting spigot unless these are cut away or the clevis is positioned far enough out from the central spigot.  - A Z-bend in the end of a control rod, if accurately made, is effective and lightweight. An alternative in installations where access is limited is a single 90 degree bend and swing-keeper  - Loose mechanical connections between snake/pushrod and servo will result in imprecise flight characteristics.  -  Your transmitter functions can probably be made to counter the effects of sloppy servo installation, but should really be used to fine tune a good servo installation.  - Not all servo disks are the same - use the same brand of servo arms as that of the servo, or things can go pear-shaped.  - Servo disks can make useful throttle arm replacements

Hiya Lee If you reverse the red/black wire on the servos you will release the magic smoke, and be left with a dead servo. I have the (mis?) fortune to own some old "Black Plug" Sanwa gear, and speak from experience. The +ve and -ve wires on this gear are indeed reversed (for some unknown reason), but as the wires are all black (the positive being marked with a subtle white stripe) this is not immediately obvious. Mercifully you can't buy any of this gear any more, except off auction sites. In any case, your TX is more than capable of reversing servos, setting dual rates, making cups of tea, and filing your tax return, so you dn't need to muck about with servo wires AlistairT 

Steve There's no "right" way - I find it's best to ponder how best to approach this over a few cups of brew before committing film or blade to balsa. If you're after a really neat appearance - cut the slots for the hinges first in both wing and aileron (as hingeing tools can leave marks - and it's harder to get the slots exactly straight with shiny covering in the way). Then film the Aileron and wing TE only (including aileron tips and inside edges of wing recess for aileron), poking a sharp blade through the covering where the slots for the hinges are. If you're planning to pin the hinges, you could film the Aileron LE only, then pierce/drill the holes and insert short lengths of cocktail stick/skewer, cut to match the thickness of the wing TE/aileron LE appropriately. Once happy, glue these and cover the rest of the wing/aileron. NB - this is not a perfect solution, as the edge of the film on the aileron surfaces faces the airflow and will, in time,  peel up; usually while you're doing a fast pass. The resulting BRRRRRRRRRRRRRRRRRR noise will convince everyone who's watching that you'vegot flutter and your model is about to disintegrate into a thousand shards of balsa, plus a hot, heavy, unguided engine..... Of course if you're aware of this and prepared for it.....but they're not...  AlistairT

How big a blast pen does it need during charging?

Like I use such calculations.....ever Plug it in, fire it up, see if it smokes...... works for me

Phil check out the feature on the Keilkraft Cobra on this website: KK Cobra on Modelengine News Could be time to invest in that lathe, as they're issuing plans for this motor. The site is also well worth a browse for the other antiquarian motors that appear. AlistairT 

Ooh yes please Mr Ashbys. AlistairT

Giannis I couldn't find any test data for the graupner 350 compact - and it's not listed in either Electricalc or Motocalc (online motor test software). See; Fly Electric Motor Constants This will (if you have the patience and the figures) tell you how your motor should perform. However - it really is far simpler just to buy a tester, and set aside an hour to test your motor on various props, until you've narrowed your choices down to two or three of similar pitch/diameter. You can then test these in flight to se which "feels" right. AlistairT

Nigel Hawes did a review back in.....oooh....a long time ago - a ha! 2004 (see list of back issues on this website): See the following pages of the listed issues: Formosa  Jul:93-6,  Aug:96-100,  Oct:40-1 Nigel went for a similar 950Kv brushless in the end, with lipo, and got good results - I can't remember the prop sizes. OH - hang on - have you got the Formosa MK1 or MK2? The MK2 is bigger, so you may need a beefier motor than Nigel used in the MK1. If it's a MK1, Fellside Precision Cutting do a CNC plywood motor mount. AlistairT

Ouch Peter Miller designed a Cessna Skymaster for twin coxes in nineteen eighty something..... funnily enough I've sourced the plan for it and, in due course, I'm hoping to build one. Coxes can still give you a nasty bite, but I don't think they're up to removing pinkies. Peter Miller's cessna is supposed to be made from this funny stuff called BALSA WOOD. I believe this to be a form of carbon fibre, as the man on the telly keeps bangin' on about tropical forests being places where carbon goes to - and BALSA WOOD is apparently made in tropical forests. Tsk - couldn't he be bothered to order some Depron off the internet? AlistairT

I remember that one! The first club I joined (Impington Village College MAC) brightened its newsletters with liberal use of similar such cartoons, all penned by Ray Malmstrom. His "Flyer Phil" appeared in all manner of imaginative aeronautical machinery - replete with bryl-creamed hair, suit and tie. AliT

I could arrange a 21-cox salute, if someone volunteers to help me start 'em all at the same time.... 21 x 18,000 rpm.....that's.....a lot

Eric - you available at the weekend to launch a twin-cox-powered microjet? You sound like just the sort of person....

Absolutely. I installed a PAW 1.49 in the last one that flew - it took a lot of church roof to balance, and flew with more authority, but not much faster - just an amazing shape in the air. AlistairT

Bob I've built two of those! I only got a mangled finger once when trying to swap launch hands with the engine running - it was only a mills 0.75 but ouch did it bite! I'm planning to make another two - one with .09 - .10 engine, one electric. The absolutely safest way to launch the wingamagig (I've found) is above the head with a hand grasping the LE on either side at roughly half span. This puts the prop directly above your head - but above by quite a long way. It then starts off quite a way above the ground, even if the launch is half hearted. AlistairT