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unidentified thruster object

Guest fly

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Hi All


Wondering if someone can tell me what the following object is ? [T500]


Internally on the roof inside the pod is a diamond shaped chrome plate fastened to the centre front of roof by 4 rivets, 2 of which go into the boom


The plate has a 7/8 dia by 1 1/2" long [approx ]peice of tubing and a 1/4 dia by 3/4" long peice [approx] protruding vertically down ??


Me thinks maybe .. choke levers. or maybe to hold up eyebrow panel which I dont have .


Which by the way if anyone has the choke lever set up which attaches to the roof somehow? I would willingly pay good money for.


I am about to purchase a new windscreen,


Is the raised section up to the wing a big plus against drag ,


as I am thinking about wiring / fuel lines/ cables etc all have to head in that direction through a raised section


Everyone seems to mount the mikuni vac pump down low attached to motor mounting bolts [ rubber mounted of course]


Ive been told to mount the pump, by someone who is no fool, so that the pulse fitting of the pump is above the vac fitting on motor to facillate drainage via the pulse line back into sump,


I know there is a needle hole underneath the pulse fitting


Any thoughts or experiences on this.


thanks all................ Fly



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Guest TOSGcentral

Fly, your Thruster “UTO†is the standard mounting for the single or double choke levers.


1. The larger tube you should find is transversely drilled and this takes the mounting spindle for the levers (which it sounds that you have not got but may still be with the levers wherever they are now mounted – as they have the friction controls to prevent the springs in the carbs pulling them closed).


The front smaller tube appears to serve no purpose other than as a brace to avoid overstraining the rather small footprint and mounting of the fitting.


  • Extending the windscreen higher will indeed assist in reducing the interference drag between wing and fuselage (I am doing this by a GRP fairing on the Swift as I need air intakes up there for part of the new ventilator system). However you should also put in side panels as well to seal the entire under section. I will post some pics later to day so you can see what I am talking about as I have an extended windscreen arrangement sitting in the workshop at the moment. This will also show how to route the various harness etc through the windscreen extenstion.
  • I do not see much point in moving the mechanical lift pump. They give faultless performance in their standard position (which you apparently have) and have done so for years.







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Guest TOSGcentral

Images as Promised


OK – this is Fly’s Thruster “UTOâ€Â. It is actually a quite standard fitting on two seat Thrusters. This one is rigged for single carb choke.


(click on thumbnails to enlarge)



This is the extended windscreen for anti-interference drag between the wing and cockpit.



A few points to note:


  • It is not yet certified – but I have that in hand.





  • The windscreen extension needs to be extended by a further seal rearwards to the back of the door (or cockpit entry) opening. In this case it has been done by a hinged panel (both sides) to enable access to that area on the fully rigged aircraft.





  • This example has been rendered in polycarbonate and should have a “U†section rubber or poly protector strip along the top. For best results you need a firm seal between the fairing and the lower wing skins and the bare polycarbonate will abrade the Dacron.





  • Access of services and systems is shown and is a simple hole drilled through the extended windscreen.





  • What you cannot see in the image is that there is also a rear partition fairing to seal the area and prevent “curl in†airflow around the fairing sides – that would add to drag.








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Hi Fly,


The choke levers are standard bicycle parts, (used to change gears I think) ("thumb gear lever"?). They have little butterfly friction nuts. I think the clamp they attach with is either a standard bicycle part, or a standard bicycle part with another stub welded onto it. You will notice the large tube sticking down from the diamond bracket is the same diameter as bicycle handlebars.


The choke cable is also a bicycle part , the only tricky part is the blob on the carbie end of the bowden cable. (I think it's not a standard bicycle part).


I also thought these levers were fitted as standard to T500's.


Re pulse fuel pump, No-one in my group of pilots has had any problem with the fuel pump position, you get a little bit of oil accumulation in the pulse line but doesn't seem to affect anything.


One thing you should do however is to replace the fuel lines, the braided PVC ones get brittle after a few years service. I think I've replaced the exposed fuel lines up the engine end with externally SS braided polyurethane racing boat fuel line. I was planning on using milspec fuel line with firesleeve over , but it would have been too bulky. Standard aircraft practice requires fireproofing of all fuel lines forward of the firewall. In the Thruster all you get is part of the line run in aluminium tubing :<(


Try to minimize the amount of fuel splashed on your windscreen to postpone the onset of stress cracking in your windscreen (quite visible in one of Tony's pics) Also be careful when cutting and drilling the Lexan (polycarbonate), smooth all the edges before bending, and make smooth holes. Also be wary that some types of plasticisers used in rubber washers, grommets and rubber edging will also promote the stress cracking. In theory the stress in the curved windscreen can be relieved by heating it (e.g. by using a bar heater at a reasonable distance, hot air guns are a no-no) but the temperature is quite touchy, supposedly around 110-120C should do it, and it will start to sag/distort at around 140C , and melt at 160C, so if you have a contact thermometer and some offcuts to practice on , you might want to give stress relieving a go. Also on the topic of windscreens, mine is distinctly asymmetrical, so if you use the old one as a cutting template make sure the new one goes on the same way around!


Cheers, BobT



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Thanks Bob, have taken it all on board,


using tygothane fuel line,


I was going to let the lexan warm in the sunshine,


will check out some older bike shops ,





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