Acro Wot ARTF (balsa) chat

[Stuart Z]

Posted by Jon - Laser Engines on 19/12/2018 09:18:33:

I would throw any manufacturers c/g out the window to be honest. I dont think i have a single model set at the recommended c/g any more and only use the supplied figure for the test flights. After that i usually change it quite a bit. The worst of all was my Hangar 9 pulse. The c/g was so conservative i must have moved it an inch further back and to be honest i think it could stand to go a little more.

The info Stuart provided is good but your acrowot is not as 'straight' as a pattern ship so dont get too obsessed with it. If i were to test my warbirds to that schedule they would all be condemned! Getting a good setup on the model is very important, but dont get caught up in the minutia if you are just looking for a bit of sport flying and dont forget the model you are flying. Not everything will respond to that schedule in the same way and you might end up chasing your tail.

Remember too that trimming is not a static thing and will vary day to day. Wood expands when damp, metal pushrods contract when cold etc. Its not uncommon for models to be out of trim after a change in weather.

However, the info will be useful as it covers a lot of general setup items that are well explained

S

[Bruce Collinson]

Glenn,

Ta; totally different, as you say following major surgery.

Chris, ta also; still within the +/- 6mm makes me less nervous so I will try a tweak.

Stuart Z; very helpful link. As one who defaults to a Wot 4 immediately followed by an Acrowot, both leccy but see passim, I found this thread very valuable.

BTC

[Sheldon Holy]

Does this forum include the XL? If so, here is some progress on mine.

 

All normal Acro Wot XL assembly, with some exceptions. I had a power plant available for a model of this size and, for many reasons, I really wanted an Acro Wot XL. The Acro Wot is probably the nicest flying power model I've ever flown, and it looks great too. Even the foam one flies beautifully. The ARTF is also very cheap for the size, and whilst it is a "budget" kit, there is really nothing to complain about quality wise. All ARTF models come from the same factory anyway, Hangar 9 for example is made in the Seagull factory...

 

Anyway, the Chris Foss ARTFs are out of stock everywhere and many have no delivery dates, Acro Wot XL included. Luckily I found a kit at a model shop in Germany, it cost an extra £50 or so but still worth the money. Unfortunately, it arrived without the cowl or landing gear in the box which appears to be a mistake from the factory. No reply from the model shop, so I guess that's that. Anyway, I found a set of Alphawing Xtra Wot size landing gear at SMC which is a near perfect fit, and I am making my own cowling anyway....

 

All normal so far.

And then I made a hole in the front....

... Because I want to fit this:

It's a P20 with a CNC Modelparts turboprop unit. I've always wanted a turbine (who doesn't!) but no local flying sites are suitable. Turboprops are another several levels of interesting higher for me, especially this miniature PT-6 style unit with a free secondary turbine. I like how the engine is backwards, amongst other things (did I mention it's a turboprop?!). Some considerations:

- No vibration from the turboprop and they are surprisingly quiet, usually quieter than a two stroke petrol

- They drink fuel, this will need a litre tank for a safe 8 minute flight. Also it's long, so the turbine sits where the tank normally would. Luckily the fuselage on this model is a good size with loads of room for the turbine and a 1L tank to sit on the CG, with heaps of room left for batteries etc...

- Engine/gearbox weighs about 1450g, so about the same as the NGH 38cc four strokes that sometimes go in these models.

 

I felt it necessary to at least try and make a slightly interesting engine mount, so I came up with the following:

 

I need to tidy up the hatch, sort a cowl (plan on carving blue foam and then glassing) as well as sorting out suitable ducting to ensure the airflow to the turbine intake is isolated from the hot section. 

 

I also fitted dual elevator servos at the tail and cut the tail post to properly epoxy the horizontal stabiliser in. CAing it in place seemed inappropriate as it wasn't a 100% snug fit anyway.

 

Another reason I went for this model is I already have everything I need. I will be going for a dual receiver setup as per my other larger model (H9 super cub). One receiver and battery for each half of the plane, fully independent.

I had to stagger them to make the fit:

 

And that's where I've left it for the evening. I will pick this project back up when I have some time, but hopefully not too long. The gubbins for the turbine (lipo, fadec and pump) don't take up much room and the tank fits nicely:

 

 

 

Edited By Sheldon Holy on 07/05/2019 00:04:14

[KEVIN CAMILLERI]

WOW !¬! ! Keep it up !

Posted by Sheldon Holy on 06/05/2019 23:30:35:

Does this forum include the XL? If so, here is some progress on mine.

All normal Acro Wot XL assembly, with some exceptions. I had a power plant available for a model of this size and, for many reasons, I really wanted an Acro Wot XL. The Acro Wot is probably the nicest flying power model I've ever flown, and it looks great too. Even the foam one flies beautifully. The ARTF is also very cheap for the size, and whilst it is a "budget" kit, there is really nothing to complain about quality wise. All ARTF models come from the same factory anyway, Hangar 9 for example is made in the Seagull factory...

Anyway, the Chris Foss ARTFs are out of stock everywhere and many have no delivery dates, Acro Wot XL included. Luckily I found a kit at a model shop in Germany, it cost an extra £50 or so but still worth the money. Unfortunately, it arrived without the cowl or landing gear in the box which appears to be a mistake from the factory. No reply from the model shop, so I guess that's that. Anyway, I found a set of Alphawing Xtra Wot size landing gear at SMC which is a near perfect fit, and I am making my own cowling anyway....

All normal so far.

And then I made a hole in the front....

... Because I want to fit this:

It's a P20 with a CNC Modelparts turboprop unit. I've always wanted a turbine (who doesn't!) but no local flying sites are suitable. Turboprops are another several levels of interesting higher for me, especially this miniature PT-6 style unit with a free secondary turbine. I like how the engine is backwards, amongst other things (did I mention it's a turboprop?!). Some considerations:

- No vibration from the turboprop and they are surprisingly quiet, usually quieter than a two stroke petrol

- They drink fuel, this will need a litre tank for a safe 8 minute flight. Also it's long, so the turbine sits where the tank normally would. Luckily the fuselage on this model is a good size with loads of room for the turbine and a 1L tank to sit on the CG, with heaps of room left for batteries etc...

- Engine/gearbox weighs about 1450g, so about the same as the NGH 38cc four strokes that sometimes go in these models.

I felt it necessary to at least try and make a slightly interesting engine mount, so I came up with the following:

I need to tidy up the hatch, sort a cowl (plan on carving blue foam and then glassing) as well as sorting out suitable ducting to ensure the airflow to the turbine intake is isolated from the hot section.

I also fitted dual elevator servos at the tail and cut the tail post to properly epoxy the horizontal stabiliser in. CAing it in place seemed inappropriate as it wasn't a 100% snug fit anyway.

Another reason I went for this model is I already have everything I need. I will be going for a dual receiver setup as per my other larger model (H9 super cub). One receiver and battery for each half of the plane, fully independent.

I had to stagger them to make the fit:

And that's where I've left it for the evening. I will pick this project back up when I have some time, but hopefully not too long. The gubbins for the turbine (lipo, fadec and pump) don't take up much room and the tank fits nicely:

Edited By Sheldon Holy on 07/05/2019 00:04:14

[KEVIN CAMILLERI]

WOW !¬! ! Keep it up !

Posted by Sheldon Holy on 06/05/2019 23:30:35:

Does this forum include the XL? If so, here is some progress on mine.

All normal Acro Wot XL assembly, with some exceptions. I had a power plant available for a model of this size and, for many reasons, I really wanted an Acro Wot XL. The Acro Wot is probably the nicest flying power model I've ever flown, and it looks great too. Even the foam one flies beautifully. The ARTF is also very cheap for the size, and whilst it is a "budget" kit, there is really nothing to complain about quality wise. All ARTF models come from the same factory anyway, Hangar 9 for example is made in the Seagull factory...

Anyway, the Chris Foss ARTFs are out of stock everywhere and many have no delivery dates, Acro Wot XL included. Luckily I found a kit at a model shop in Germany, it cost an extra £50 or so but still worth the money. Unfortunately, it arrived without the cowl or landing gear in the box which appears to be a mistake from the factory. No reply from the model shop, so I guess that's that. Anyway, I found a set of Alphawing Xtra Wot size landing gear at SMC which is a near perfect fit, and I am making my own cowling anyway....

All normal so far.

And then I made a hole in the front....

... Because I want to fit this:

It's a P20 with a CNC Modelparts turboprop unit. I've always wanted a turbine (who doesn't!) but no local flying sites are suitable. Turboprops are another several levels of interesting higher for me, especially this miniature PT-6 style unit with a free secondary turbine. I like how the engine is backwards, amongst other things (did I mention it's a turboprop?!). Some considerations:

- No vibration from the turboprop and they are surprisingly quiet, usually quieter than a two stroke petrol

- They drink fuel, this will need a litre tank for a safe 8 minute flight. Also it's long, so the turbine sits where the tank normally would. Luckily the fuselage on this model is a good size with loads of room for the turbine and a 1L tank to sit on the CG, with heaps of room left for batteries etc...

- Engine/gearbox weighs about 1450g, so about the same as the NGH 38cc four strokes that sometimes go in these models.

I felt it necessary to at least try and make a slightly interesting engine mount, so I came up with the following:

I need to tidy up the hatch, sort a cowl (plan on carving blue foam and then glassing) as well as sorting out suitable ducting to ensure the airflow to the turbine intake is isolated from the hot section.

I also fitted dual elevator servos at the tail and cut the tail post to properly epoxy the horizontal stabiliser in. CAing it in place seemed inappropriate as it wasn't a 100% snug fit anyway.

Another reason I went for this model is I already have everything I need. I will be going for a dual receiver setup as per my other larger model (H9 super cub). One receiver and battery for each half of the plane, fully independent.

I had to stagger them to make the fit:

And that's where I've left it for the evening. I will pick this project back up when I have some time, but hopefully not too long. The gubbins for the turbine (lipo, fadec and pump) don't take up much room and the tank fits nicely:

Edited By Sheldon Holy on 07/05/2019 00:04:14

[Andy Stephenson]

I'm looking at my rather sad 1986 built original Chris Foss Acrowot and thinking of refurbing it but the only thing holding me back is the canopy which is yellowed and buckled.

Does anyone know where to get a replacement. I have looked at Carbon Copy but I would prefer a transparent one if possible.

Thanks,

Andy

[Ron Gray]

Have you tried Chris Foss?

[cymaz]

 

 

 

Here ( I think the tinted one is better looking )

Edited By cymaz on 19/10/2020 06:50:44

[Ace]

Vortex probably have a suitable bubble if you are struggling.

Vortex

[Andy Stephenson]

cymaz,

Many thanks, the price of the one from SMC is a of a shocker, it's only a pound less than the Carbon Copy one but that's the one I'd go for and I would lightly tint it with some smoke spray.

Ace, many thanks but the trouble with trying to find a canopy from the Vortex or Sarik ranges is, unless it is specifically for the model you want it's difficult to know if it will fit or even judge a suitable shape from the photos.

I also looked at Chris Foss' website but no mention of canopies as spares.

Andy

[Keith Berriman]

Would a call to Chris Foss be helpful?

[David Davis]

I am in the final stages of assembling an ARTF Acro Wot, standard HS 311 servos throughout, Laser  70 in the nose. I am at the stage of trying to ascertain the cg position.

 

I don't think it's far out, especially as I have fitted heavier wheels to the undercarriage, so this may be a daft question but with a low wing model like the Acro Wot, do you balance it upside down or in the normal upright flying position?

 

 

[Glenn Philbrick]

I find with low winger it's easier upside down.

[EarlyBird]

3 hours ago, David Davis said:

do you balance it upside down or in the normal upright flying position?

Upside down, I think.

[EarlyBird]

After three hours two come at the same time, like London buses or so I am led to believe. ?

[David Davis]

Thank you gentlemen.

 

[David Davis]

Just a brief update on my ARTF Acro Wot fitted with a new Laser 70. I only made two modifications:

 

1. I threw some epoxy resin liquid into the tank bay/undercarriage mounting having heard stories of the undercarriage ripping out in any less than perfect landings. This must have worked because I have probably flown at least ten flights with it by now and not all of the landings were perfect, indeed one or two were on the glider strip alongside our tarmac runway which is full of mole hills and the holes they leave behind.
2. I replaced the metal clevises with Kavan clevises only because one of the supplied clevises broke on assembly. Perhaps I ought to replace the plastic clevises supplied in the kit with metal ones too.

It flies beautifully. The wife of one of my clubmates was most impressed when I did a couple of rolls to the left followed by two to the right. She said that she had never seen anyone do that at the club before, mind you, we have a lot of novices in our club including her husband and I couldn't do these manoevres with any other model in my collection.

 

It certainly can do any manouevres I'm capable of. I'm very pleased with it and the engine is a beauty. It ticks over like the proverbial Swiss watch.

 

I have a Dave Smith Models Aerostar 62 to restore over the winter, or maybe I'll just tidy it up a bit and use it as a winter hack. Either way, I can't wait to fly it!

[David Davis]

I ripped out the undercarriage in something of an arrival a few months ago. I added some 1/4" sq balsa to increase the glueing area then epoxied it back in place. That seemed to have solved the problem until I put the model onto my workbench the other day when the undrcarriage collapsed again!

 

Obviously I need to reinforce the undercarriage plate. I thought of replacing all of the wood between the firewall and the wing-mount former with good quality 1/4" plywood with triangular section balsa along each side. Does anyone have any other ideas?

 

I will also need to improve my landings!

[Zflyer]

Ply rails between the formers then ply plate seems best option i think.

Or being really radical strength the wings and put u/c legs on there. 

[Eric Robson]

I had the Ripmax Acrowot and run out of strip and pulled the ply plate off. I replaced it with a 3/8" ply plate and fibre glassed it in as epoxy does not take to good after fuel contamination I used 5mm nylon bolts which snapped regularly but easy to replace. I currently fly the original Chris Foss one I built from the kit and despite a few hard landings the undercarriage has been no bother. 

Mounting the undercarriage in the wing on an Acrowot would be too far back for a tail dragger so a trike set up would be necessary  

[Bruce Collinson]

Both mine have suffered u/c plate failure and reinforcement with triangular stock then glassing seems to be the way forward, although access is poor.   Nylon bolts (by the hundred from Ian Shaw) is Plan B.

 

I even had a plate pull out on takeoff last winter as it must have hit something unpleasant on the strip.

 

If your clubmates' wife was in awe of two rolls with this, she'll be quivering if you get/got the Aerostar commissioned!

 

BTC

[Zflyer]

Yes the u/c being wing mounted would have to be raked forward. I think some of the ww2 aircraft, messerschmitt's were. 

[David Davis]

Several people have recomended glassing the mount. How do you do this? Do you saw off the balsa block on top of the fuselage to get access from above?

[David Davis 2]

Ah! I think the penny's dropped! You beef up the structure and glueing area inside the tank bay then apply glass fibre mat to the outside. I have some finishing glass fibre mat. Will that be strong enough?

 

I stripped the old covering from the Aerostar's fuselage yesterday.

[Bruce Collinson]

7 hours ago, David Davis 2 said:

Ah! I think the penny's dropped! You beef up the structure and glueing area inside the tank bay then apply glass fibre mat to the outside. I have some finishing glass fibre mat. Will that be strong enough?

 

I stripped the old covering from the Aerostar's fuselage yesterday.

I'd use what you use for joining wings, likely much heavier than 24 gm finishing mat.   It's the front joint which needs reinforcement as the impact on the u/c exerts a lot of rotational stress on it, twisting it backwards.   Ultimately it becomes a problem of how far around the weak point do you spread the load, adding weight and potentially pulling the fus apart rather than just pulling the u/c plate off.   That's probably when to fit nylon bolts!

 

BTC