Volume 8 No 3 Jun 1957.pdf - Lakes Gliding Club

for overhaul. The difficulty is that even if properly. Use these tensions as a guide toone knows what is wrong with them, they the setting of aileron cables. Rudder cablesmuSt be checked fOT accuracy after any on most gliders are bungee-tensiQned in theadjustment, and this almost always requires, nose of the machine, and in this case theya special ,calibrating gadget of some sort. look after themselves as regards tension.However, to prevent trouble developing, the We are assuming, of course, in all thesefollowing points should be borne in mind:- tests, that the control circuit is properly1. Use good quality rubber pi~ for the lubricated.col1J1e(;tions, and replace it whenever Safety and Lockingthere are any signs ofperishing.2. Keep moisture and dust out of All parts of a glider must be so fitted andinstruments and their piping.locked that there is. no risk of anything3. Do not subject instruments to rough working loose or coming undone. We cantreatment, shocks, etc." and do not consider turnbuckles first. One commonlyblow into Air Speed Indicators or used type has a barrel in which ,there is aVariometers.socket at each end with right and lefthanded threads. Inlo these sockets screwCablesthe eyebolts. With this type, all the threadsMost gliders use cables in ,their control of the eyebolts must be inside the barrel ifcitcuits, and it is most important to keep the tumbuckle is' "in safety" or able tothe cable tensions correct. If the tension is develop its full strength. If any threadstoo slack there is a risk of tumbuckles show, then the cable must be increased infouling ribs or bulkheads, while if the cable length, by the addition of links, etc., tois, too tight the fittings may be subjected to allow full engagement of all the threads. Aunnecessarily large loads. The effect of "g" second type of tumbuckle, found onon cable loads must not be overlooked. In a Olympias and other gliders, consists, of aloop, for example, the elevator cable ofm0st right and left handed screw for the centralgljders is subjected to quite a big increase in portion, apd this fits into two sockets whichtension, since it is only supported at two ate swaged ()nto the ends of the cable. Inpoints about 15 feet apart. Due to the extra this type the central screw is threaded"g," it tries to sag, and if the tension was almost up to the middle, and there is atight to start with, the increase of tension different method of determining whethermay be veIY great . sufficient threads are engl\ged with theCables tend to stretch and shrink as the sockets to provide full strength. On eachtemperature increases or decreases, so they socket will be found a small hole, aboutmay require adjusting fairly frequently. t inch from the mouth of the socket, and"'hile on this point, remember that a sail~ this is the "safety hole." The socket is "inplane sittiflg on the ground in a temperature safety" if the screw has been screwed in pastof 7soF. or more, on a ,fine sunny summer's this hole. This must be verified, either byday, may well be at 8,000 ft. a short time looking into the hole or by feeling with alater, where the temperature will probably pin or piece ofwire. Thistypeoftumbuck1ebe around freezing point; so do not over- also has two brass locknuts whjch should betighten the cables in summer.screwed back against the sock-ets when theWhat is the COrrect tension for cables? adjustment is co~t. In spite of theseThis is a very difficult matter to desctibe in locknuts, the tumbuckle must be properlyprint, and is much better learnt by an actual wire-locked as described below.,