Acrowot with laser 80

[Tim Flyer]

Cheers Graham. I can honestly say the slipstream airflow has never yet been a problem on the carb. One thing that is bad though I have seen is when a carb is enclosed in a cowl and too near The firewall. If it gets warm and restricted air that’s a problem. I think the main thing is just having a decent flow of air around it . Petrol carbs are much more prone to overheating as the fuel quantity used is less than in methanol engines plus as Jon mentions often the latent heat effect of methanol keeps the carb cooler. That’s why petrol engines need plastic insulator blocks on their carbs.

[Tim Flyer]

Did 3 “maiden” flights today . It’s a superb plane..the Laser 70 is a real screamer . The vertical on this plane seems unlimited and the high revving engine really helps. The wind was 25mph and gusting and this light plane was buffeted around especially when I was landing. Even so it’s aerobatics were great. I got two good landings and one cartwheel after getting caught in a gust so called it a day after that! The damage was only very minor though and I look forward to flying it at the weekend.

[Tim Flyer]

[Paul james 8]

Great news! Makes me want to get on with my new one

[Former Member]

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[Former Member]

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[Tim Flyer]

Hi Percy that’s what I have . It is using a 13x6 APC and it really goes ! I’m “just running in “ at the moment but full throttle is quite something. Maybe it’s my custom “tuned header” 🙄. Anyway it’s certainly a great fun plane . It’s a great little brother for the big Acrowot and I do find the smaller planes more convenient and quicker and easier when to set up when I’m pushed for time .

[Tim Flyer]

By the way Paul I had to add10g of lead on the tail. If I did the build again with the 70 , I would have put the throttle servo next to the rudder servo as per instructions. I did also replace the heavy wooden elevator pushrod with a light weight carbon one . That may have also affected it a bit. 

Edited By Tim Flyer on 10/04/2019 18:20:52

[Paul james 8]

Posted by Tim Flyer on 10/04/2019 18:19:25:

By the way Paul I had to add10g of lead on the tail. If I did the build again with the 70 , I would have put the throttle servo next to the rudder servo as per instructions. I did also replace the heavy wooden elevator pushrod with a light weight carbon one . That may have also affected it a bit.

Edited By Tim Flyer on 10/04/2019 18:20:52

That is a bit of a surprise as my old one, with a Saito 82 up front has a big slab of lead on the firewall. Balances perfectly and flys well for an old un. I've got a Kyosho spitfire to sort out first then maybe on to the new Acrowot.

[ASH.]

Looking good Tim. Could you give some more details on your flexi pipe arrangement. Is there any brazing involved and how is it affixed to the engine?

I have a Laser 70. Will like to use it one day without the muffler if I can.

Also, the AUW on your model? I use a 14x6 APC on my Saito72, gives good thrust, torque and flywheel effect. No "flameouts" ever. Tried lighter Graupner 13x6 and 14x6 wood and found engine cut on the down verticles coming out of a loop. 

 

 

Edited By ASH. on 10/04/2019 23:41:51

[Jon H]

Our 70 is/can be a screamer if you so choose. Its good to 14000rpm if you really want. I personally wouldnt use it over 10000 or below 9000 in general use. 13x6 gives you around 10k, 13x7 around 9k. 12x7 sits up near 10 again. 14x6 is likely to be a little to much if you want maximum performance.

[Tim Flyer]

Hi Jon I agree it’s interesting the characters of each of your engines. This one can really rev so definitely can go fast . 😊. I’m getting all I need on the 13x6 but may have a go just for info on a 12x7or 13x7. On the 13x6 I don’t need much more than half throttle for all the aerobatic stuff. It’s very good on fuel too. I’m getting close to 15min on my 10oz tank and coming in with spare fuel. Hi Ash the AUW is about 2.85kg or 6.28lbs. It feels very light to me vs my heavy kit built Acrowot which I built like a truck😉.

Regarding the exhaust it is a stainless flexi-pipe with a brass sleeve (7/16” or 11.1mm diameter) silver soldered on the end which slides into the exhaust outlet with a fairly tight fit. I did put a dab of high temperature red silicone on it to ensure a total seal(the standard manifold uses o rings). The end of the SS flexi pipe has a smooth tapered section which fitted nicely into the brass sleeve for silver soldering. The standard laser exhaust clamp holds the sleeve in place . I used the cut out under the plane to mount a home made simple aluminium exhaust bracket. The pipe is held to the bracket with a steel jubilee clip with red silicone on the inside. That allows some flexibility whilst still gripping the pipe. Exhaust systems should not be totally rigid as cracks can develop longer term as the engine does shift slightly when running. I’m out today but happy to post more info.

Edited By Tim Flyer on 11/04/2019 08:58:40

Edited By Tim Flyer on 11/04/2019 09:01:42

[Jon H]

The character of an engine is everything. Some are fussy, some are laid back, some are vicious, and some even seem bright and happy to see you start them up. Its quite remarkable really and can make quite a difference to the enjoyment of a model.

Tiger moths etc call for a laid back sort of engine that really couldnt give a rats about anything you throw at it, where as the acrowot demands an engine that likes to get up and go. Swap them around and the two models just would not feel right. It should be noted though that many engines have dual personalities as a prop change on our 180 can make it laid back (20x6 etc) or pretty lively (17x10 or 18x8).

Running our range on the test bench is always a fun time and the 240v is one of my favourites as i slap a 16x8 on it and wind it up to near 10k. Having a 40cc twin screaming away at those sorts of revs always brings a smile to my face

I dont recommend flying it at those revs though, might be a little loud

[gangster]

Posted by Paul james 8 on 10/04/2019 22:47:15:

Posted by Tim Flyer on 10/04/2019 18:19:25:

By the way Paul I had to add10g of lead on the tail. If I did the build again with the 70 , I would have put the throttle servo next to the rudder servo as per instructions. I did also replace the heavy wooden elevator pushrod with a light weight carbon one . That may have also affected it a bit.

Edited By Tim Flyer on 10/04/2019 18:20:52

That is a bit of a surprise as my old one, with a Saito 82 up front has a big slab of lead on the firewall. Balances perfectly and flys well for an old un. I've got a Kyosho spitfire to sort out first then maybe on to the new Acrowot.

Interesting that I have an asp70fs up front and also have a sizeable chunk of lead at the front. The RCME review also spoke of a few ounces of lead. So have they changed them in any way.

[Tim Flyer]

Cheers Jon ...that bit of the engine testing sounds fun! I must admit I do enjoy engines it’s all about the right engines the right application. Obviously there are good and bad quality engines but engines are always suited to a particular purpose depending on torque and rpm cubes. There are lots of combinations of stroke bore and capacity ...matching props to all that and it certainly becomes a bit of an art getting it right . Obviously experience is the most useful! .

Re the Acrowot weight . 10g on the tail is just a slither. The engine thrust seems very well above the 6.28lb all up weight. However up front I did add reinforcement plus baffles and aluminium scoop in the cowl. I also used my own beefy laser engine mounts as the kit ones were missing. The other thing I customised were the cowl fixings. I have an aversion to wobbly threaded screws in fuel soaked holes in the cowl . I used glued in stainless steel threaded inserts in the wood with plastic m3 cowl screws . The plastic screws do not vibrate loose like metal screws do . . Kits and wood do vary so it’s possible that my tail would light but as I mentioned my hollow carbon tail rod is a lot lighter than the wooden kit one too.

[Glenn Stevenson]

I put my Laser 80 into a Seagull isport, really happy with it, the carburetion is perfect, starts easy and has plenty of power. Its too attractive to cover with a cowl though.

Thanks for all the comments

Glenn