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Rotax 503 V's 582

Guest joe

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Just after some informed (or other) opinions on whether to replace an existing 503 (on a Thruster) with a new 503 or new 582 (which appeares to be approx twice the price).


+ I believe the cooling system in the 582 has some ongoing costs/issues


as opposed to the air cooled 503. Is the extra hassle + price of the


582 worth the extra 15hp??


any advice etc would be greatly appreciated, Cheers Joe



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On something like a Thruster, I tend to feel the extra power is absorbed by the extra weight incured by fitting a 582.If


you fit a 582 you usually also want to fit electric start, a battery, a


couple more instruments, a 'C' box and probably a three blade composite


prop.Not everyone also wants to fit oil injection!It


can also have some weight and balance effects, I once tried to instruct


in a Thruster fitted with a 582 and it flew like a dog!Better to keep light, and save money. Tony could probably give a better insight.Arthur.



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Guest TOSGcentral

Hmmm! This one slipped past me!


First up – Hi Arthur! You the same guy who also contributed so much to the Vampire group a while back? How are you going?


Joe – I have a lot of respect for Arthur but I can shed more light so this will be a longish post.


You have specified the type as being a Thruster – but not which one (there are over 55 types and models!).


As a general rule of thumb do not put anything larger than a 503 into


any of the single seaters and always opt for a 582 in any of the two


seaters if you can.


The ‘exception’ to that rule is the Glasshouse (Thruster 84 TPT or Utility).


They are a lot ‘safer’ with a 582 but are more of a handful and doing a


trim set-up is a bit of a trick due to the torque. As the Glasshouse is


anyway the most challenging of the Thrusters on the ground you would


need to have a realistic grasp of your own abilities!


503 V’s 582 RATIONALE. Arthur is right in saying additional weight


absorbs extra horse power but there is such a residual additional power


in the 582 that they are very attractive on any of the two seaters (I would say essential for training). There are two main reasons:


1. The 503/two seater combo pants something fierce two up on a hot day


and can be quite exciting if you get caught in large areas of sink when


trying to climb out. They do not go too bad solo but you have no real


power left up your sleeve.


2. Due to the above the 503 does not allow you to access concepts such


as ‘Safe Speed Near the Ground’ – they just do not have the power to


sustain the speed (55 kts required on a Thruster) AND give a reasonable climb rate. Hence the amount of crashes due to engine failures early after take-off.


The 503 two seaters generally had to be operated at Max Climb Out angle


so went straight to the stall in the not uncommon event of a major


failure in those early Rotax motors. If this happened low (below about 200’ agl)


your goose was cooked as the Thruster is too blunt to regain control


speed in the height available – most therefore bellied in hard and


still semi stalled, with significant back injuries being the result!


In comparison the 582 allows the 55 knots for all of the initial climb


and still way exceeds the max possible climb rate of a 503 powered


machine. There is considerably less angst in operating them –


especially for instructors who want to concentrate on a whole variety


of things.


WEIGHT & BALANCE ISSUES. The 582 assembly is significantly heavier


than the 503. Unfortunately it looks a similar size and fits straight


onto the same mounts – so people do tend to just stick them on!


The ramifications of that can be seen by the fact that you can convert


the enclosed T500 into a T300 by taking the rear enclosure off because


you can shorten the boom and move the engine back (The T500 has a slightly longer forward boom to counterbalance the weight of the rear enclosure fabric and stringers). But you cannot do the reverse as there is no way of extending the T300 boom without replacing the entire thing!


Now, if just some dacron and light alloy tubes make that much difference you can imagine what a heavier engine (with its cooling system, starter motor and larger prop) is doing! Especially when you consider that most Thrusters tend to sit well forward in the C of G range anyway.


Doing the conversion is not a difficult task but must be done responsibly or you will get yourself into a lot of trouble!


COSTS AND ISSUES – OPERATING AND INSTATEMENT. For the benefits received there is not really any issues of any significance.


Arthur is quite right – you need an electric starter, a C type gear box


and a 68†3 blade Brolga running on 16 degree pitch blocks (to give peak power – maybe 17 or 18s for private use and a lot of cross country work). You will also need a coolant temp gauge and I prefer operating on dual EGTs so I can keep a good eye on the motor.


An E type box is the preferred option these days as you need the


electric starter as you cannot hand swing a 582 but the E box allows a


recoil starter at the back which is very handy if you have a flat


battery and they start well with these systems.


I put an entire new Blue Top 582 motor and prop assembly on a T300 a couple of years ago and it cost $10,000 just for the bits.


Once in operation there is no real difference between a 503 and 582


other than ensuring you have the correct coolant in to provide


lubrication to the oil/water seals on the transverse shaft that drives


both water pump and rotary valve – plus corrosion inhibitors. You have


a few more hoses to keep an eye on for leaks as well.


Oil injection is not an option for myself personally. Needless extra


weight in view of the oil flow is too low to present on a flow meter


and if it stops working the only warning you will get is if the engine


seizes. They may be highly reliable on motor cycles but you can pull


those over if they stop!


An insight into 582 operating consumption: I consistently returned 16


lph on intensive circuit work and 20 ltrs hr for cross country at 60


kts cruise.


IS IT WORTH IT? Depends on the individual. For myself – Yes! I flatly


refuse to instruct on a 503 two seater and am not even fond of flying


them unless I have to for air tests ect.


But it is a lot of money and care is needed these days. It seems that


the price of Rotax spares has escalated that much there would be a


deliberate deterrent running on re-building motors. With reasonable


care you can get 1000 hrs out of a 582 so it is not too bad overall and


you’re a writing off the engine at about $6 per hour.


Setting up with one is a bit different. If you buy a used engine then


the price gap between a rebuild and a new one is now that narrow it is


worth the extra bucks for total peace of mind. Bear in mind also that


even if you pick a second hand engine up cheap you will usually have to


get all the bits and pieces to go with it (cooling system, prop etc) and nothing is cheap!


Hope that has helped.







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