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Kit Built Acrowot with ASP52 four stroke?


Andy C
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I picked up a second hand acrowot some time ago with an unknown four stoke fitted.  Upon inspection it was an ASP 52, which looks like it was only fitted to teh front to sell teh plane and never flown with it (control rod not linked to throttle).
So, question is will the plane fly ok with it installed as I don't have anything larger?

Thanks

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The 52 will be ample. A guy my dad used to fly with flew one on a 48 4 stroke and it was no bother. He flew from land, water on floats, snow on ski's. It did it all. 

 

I used to have an acrowot myself with a 40la 2 stroke. It wasnt rapid by any stretch, but it flew fine and did all the aerobatics i was able to do

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 The 52fs should be adequate, power will fly it nicely, mine had a 52fs. Better to find if you are comfortable with flying  the airframe.

You can always change the engine for more lively performance if you have a need for it afterwards.

Fly what is best for yourself not others.

 

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It really depends on the intended style of flying.

Yes, it will fly with a lowly powered engine, but you will probably be on full throttle most of the time just to keep it airborne and/or to keep the momentum going. 

 

If you want it to FLY and perform some decent manoeuvres, fit a more powerful engine. 

They go nicely with a 91 F/S engine. 

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They used to put a 1.3 litre engine in the old Ford Cortina (I had a 1.3 Mk3 as a youth - don't ask) and I suppose it was just about adequate for getting from A to B but not much else ..............same thing with a 52 FS in an Acrowot - keeping the car analogy, you'll wind up with a Morris Minor. IMHO and experience, the bigger the engine, the better in a kit built Wotty if you want to get the maximum  enjoyment from it.

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21 minutes ago, Brian Cooper said:

It really depends on the intended style of flying.

Yes, it will fly with a lowly powered engine, but you will probably be on full throttle most of the time just to keep it airborne and/or to keep the momentum going. 

 

If you want it to FLY and perform some decent manoeuvres, fit a more powerful engine. 

They go nicely with a 91 F/S engine. 

 

The model would be completely aerobatic on the 52 and any suggestion that it will need full power all the time is completely wrong. Will it prop hang? no, but its not supposed to. Given the choice i would certainly take a 52 powered version over a 90 powered version. 

 

As the model is already assembled and more or less ready to go i would fly it as is. If you decide it needs more power later on then you can always fit something slightly bigger. In all honesty though i think you will find the 52 just fine unless the thing is really heavy for some reason. the 52 will probably perform best on a 12x6 prop (apc not master) and should be rather nice. 

 

 

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1 hour ago, Jon - Laser Engines said:

 

The model would be completely aerobatic on the 52 and any suggestion that it will need full power all the time is completely wrong. Will it prop hang? no, but its not supposed to. Given the choice i would certainly take a 52 powered version over a 90 powered version. 

 

As the model is already assembled and more or less ready to go i would fly it as is. If you decide it needs more power later on then you can always fit something slightly bigger. In all honesty though i think you will find the 52 just fine unless the thing is really heavy for some reason. the 52 will probably perform best on a 12x6 prop (apc not master) and should be rather nice. 

 

 

I agree. In my experience, overpowered aircraft are more unpleasant than underpowered ones. I know you have a throttle, but it never seems to be the same. My very old and heavily built (not be me, I'd like to point out!) AW weighs 6lb and flies great on an old ASP65FS. It's more than enough. Built a bit lighter, it would be even more than more than enough; a 52FS in a well build AW would be peachy...

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Thanks guys.  I think that I may as well invest some time in getting the engine plumbed in and flown.  But, I will still look out for something slightly larger to install when I find it. (please let me know if anyone has something like a 65 or 70 four stroke they want to sell ? ).

Thanks

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1 hour ago, Andy C said:

Thanks guys.  I think that I may as well invest some time in getting the engine plumbed in and flown.  But, I will still look out for something slightly larger to install when I find it. (please let me know if anyone has something like a 65 or 70 four stroke they want to sell ? ).

Thanks

 

Yes, me.  I have a good ASP 70 FS from new that briefly powered my ARTF Acrowot, i.e. VGC.  PM me if you're interested.

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2 hours ago, David Ovenden said:

Like Jon I too had an Acrowot powered with an OS 48 fourstroke.  It flew fine. Not overpowered but flew perfectly well. So yours with an FS52 should work fine too. Why not try it out as it is before buying a new engine?

 

The lads give good advice Andy, fitting a suitably sized motor to the model.

It is good for the soul to sometimes fit a big motor in a model to thrash around the sky,

But you will learn so much more about flying by fitting the ASP .52 to your model

Practicing proper throttle management that your combination will give you while both flying and landing.

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The biggest benefit of leaving the FS52 in the model for the moment is WEIGHT!. OK, you could shoehorn a .91 in easily, but the wing loading would go up, as you would probably need a larger tank as well (or shorter flight times). I have seen this model with both extremes, and I would suggest flying it for a while on the .52 and see how you get on / feel. On the other hand, you could always convert to electric!. Good luck with it either way.

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I have an Acrowot ARTF with a Laser 70 and its spot on published weight and has no additional lead to achieve C of G. It flies super nice and does everything either I or one the club instructors can chuck at it.

 

One other point, my Acrowot floats/flies very nicely when landing and stops in a very short distance, as mentioned when adding a bigger engine so the wing loading goes up. I was really quite surprised with a club members wots wot 90FS at how fast it came in to land, its abrupt stall and the tendency to rip the UC out of the fuselage!

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  • 1 year later...

I was gifted a kit built Wots Wot with a 60 2 stroke in it.  I fitted my OS 61Fx and that flew well but did not provide a vertical upline of the length I wanted.  I then fitted an OS91FX (a bored out 61s so a bit lighter) and that was much better but needed propping down to the 2nd lowest size to access the power and that just about holds speed around a large loop.  The big OS silencer does a grand job of keeping the noise well in check.  It depends on whether you want to fly an aerobatic aircraft that loses speed as soon as you start flying vertical manoeuvres or that will slow down by itself for a stall turn that goes up considerably in height.  You do need to know how to use the throttle throughout the flight though.

 

However, my Wot 4 ARTF with an Irvine 53 and throttle pipe out performs the Wots Wot since the latter is a good deal heavier.  This engine combo gives the Wot 4 almost unlimited vertical climbs.  That having been said, both are afflicted with a number of aerodynamic faults that make flying really good aeros quite tricky.

 

Both are flown at just over half throttle (properly set up throttle curves) and perform club aerobatics with ease.

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My old kitbuilt Acrowot, that I've regretted selling ever since, had a .91 FS and was strengthened in a number of places particularly the U/C mount area to cope with a very rough patch that we flew from for a while. Yes, it was heavier than normal, but the advantage was that the model was a doddle to fly in very windy/gusty conditions, cutting through rough air like butter that would make more lightly loaded types with modest power a handful - especially on landing.

On calm days it would still float in nicely - that lovely thick wing doing its job as the designer intended. IIRC in the instructions, the very benign nature of the wing was highlighted by CF and his suggestion was to fit 'Toblerones' to the outer wingsection LEs to make it more 'flicky' if that was what you wanted. 

This is the beauty of Chris Foss's original design, there's so much scope for personalisation should you wish it.  Build as per instructions and you'll have a great general purpose sport model - do a weight reduction excercise and you'll have a great model - overpower it and put the weight up and you'll have a great model.

A remarkable product, no wonder it's stood the test of time. I suppose the Mick Reeves Gangster has a similar story.

Edited by Cuban8
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On 08/02/2022 at 09:13, Jon - Laser Engines said:

 

The model would be completely aerobatic on the 52 and any suggestion that it will need full power all the time is completely wrong. Will it prop hang? no, but its not supposed to. Given the choice i would certainly take a 52 powered version over a 90 powered version. 

 

As the model is already assembled and more or less ready to go i would fly it as is. If you decide it needs more power later on then you can always fit something slightly bigger. In all honesty though i think you will find the 52 just fine unless the thing is really heavy for some reason. the 52 will probably perform best on a 12x6 prop (apc not master) and should be rather nice. 

 

 

I can't believe I'm typing this, but I actually agree with Jon on something!

 

As stated, just because we can put heaps of instant power in a plane does not mean we should or have to do so. The art of managing the energy of the plane in flight to transition from one manoeuvre to another is a skill largely ignored now. Why bother when you can just whack open the throttle* and go vertical to deal with any problems?

 

Plus, a kit built Wot 4 will be heavier (so better in wind) and a large, thick prop at idle as you flare will act almost like an airbrake, allowing you to put the plane down pretty much where you want on the strip.

 

*Not convinced "throttle" is the correct term when talking about electric. Discussion for another time.

Edited by Lima Hotel Foxtrot
'cos.
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Hi Lima Hotel Foxtrot

 

You have misconstrued what I was saying.  I should say up front that I fly competition aerobatics and the aircraft used must not exceed 2 mtrs either in span  or length, and nor must they exceed 5 Kgs (with batteries for electrics but without fuel for IC).  The point about having a lot of power, which these aircraft have (around 3 kW, is that you can fly large manoeuvres at a constant speed.  Try doing that with an underpowered aircraft that loses speed the moment you pull into the vertical despite applying full power.  The key thing is to manage the power and that takes a lot of training.  It's not just a case of banging in power when things go wrong - they rarely go far wrong because you can see the problem usually before it gets to you.  

 

A vertical stall turn which is required to climb some 500-600 ft requires this power.  It has to be managed all the time and is one of the most difficult things to learn when you take up competition.

 

My point was that the Wots Wot I was gifted was extremely marginal on being able to pull a largish loop without dropping out of the sky.  The analogy is with a low powered car on a traditional road with 2 way traffic.  In order to carry out a safe overtaking manoeuvre you need to think well ahead and build up your speed so that you are in the right place at the right time to overtake safely.  A more powerful car makes the whole exercise far easier and much safer as you are exposed to danger for less time.

 

I have no problem if you want to fly a standard club model which does not have an excess of power but I choose not to as I find it much nicer to fly large smooth manoeuvres that I don't have to rush.  Hence, putting an OS91FX in the Wots Wot as it just dropped into the old 60 bearer and bolt spacing.  In general, the "equivalent" size electric motors tend to be more powerful than their IC brothers.  They also react to power changes more quickly.  In that respect, you need to lead with an IC engine when entering, say, a loop whereas with an electric motor you can squeeze in the power as you are pulling up for the loop.

 

I can honestly say that since taking up competitive aerobatics I have learned a great deal about a great deal and I'm still learning.  It is a part of the sport that rewards those who are willing to spend time in perfecting their aircraft set up, practise their manoeuvres and aim to keep the whole thing under control. In that respect, it can be quite boring for the average club member to watch an experienced aerobatic pilot flying a schedule - until that is they find that actually flying in straight line at a constant height ain't so simple after all!

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Having flown an Acrowot with an ASP 52 it was pretty gutless in anything more than a light wind, Stick an OS 55Ax or similar and we're now talking useable power and grunt that can be flown in all weather conditions just keep it light and with some mixes for the Rudder /Aileron, Elevator  added its an OK plane that fly's well.

 

 

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On 10/02/2022 at 14:26, Chris Walby said:

I have an Acrowot ARTF with a Laser 70 and its spot on published weight and has no additional lead to achieve C of G. It flies super nice and does everything either I or one the club instructors can chuck at it.

 

One other point, my Acrowot floats/flies very nicely when landing and stops in a very short distance, as mentioned when adding a bigger engine so the wing loading goes up. I was really quite surprised with a club members wots wot 90FS at how fast it came in to land, its abrupt stall and the tendency to rip the UC out of the fuselage!

Laser 70   580gms

YS70        463 gms 

OS 90 FS 645 gms

 

Id be pretty sure that's not the engine, more the way its set up, including the idle and how its flown, bearing in mind the power of a laser 70 is much lower compared to YS more so if you include the extra weight although carrying 65 gms on an Acrowot is absolutely nothing however by fitting a YS you would save more weight which you more than likely not notice.

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