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Acrowot with laser 80

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Glenn Stevenson18/01/2019 16:33:33
19 forum posts

Hi, I have bought myself a new acrowot artf and am looking at fitting a laser 80, the prop wil be about 20 mm forward of where it should be, does anyone think its a problem or can I just find a spinner with a deep backplate to hide the gap a bit?

I have an OS 55 ax and an OS 70 fs that can be used but the Laser is too good to leave on the shelf.

Thanks

Glenn

Jon - Laser Engines18/01/2019 16:42:27
4506 forum posts
164 photos

If the cowl overlaps the fuselage a bit you can shove it forward until it just meets the firewall. Many artfs have an overlap of 15mm or so and if that is the case you are more or less sorted

make sure you mount it sideways though, inverted will be a pain in the butt when it comes to tank position

alex nicol18/01/2019 16:44:47
239 forum posts
6 photos

agree with Jon, all I'd add is if you need to use every MM of cowl overlap, epoxy a couple of ply blocks to the fire wall and fix the cowl to these

Percy Verance18/01/2019 19:18:11
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7803 forum posts
150 photos

This is am artf Acrowot problem. The kit built version instructions offer advice regarding fitting larger/heavier engines. Chris Foss advises reducing the length of the nose by particular measuements, depending on the weight of the intended engine. The primary aim here is to keep the C of G readily attainable.

A bit of surgery would also offer a cure for the artf version. Assuming a nylon type engine mount is used, a hole could be cut in the bulkhead to recess the existing mount. A new "bulkhead" could then be fixed to the rear of the existing one, but set back 15mm or so. The engine mount could then be bolted to this, and the spinner/cowl gap would be more or less as intended. This is one of the advantages of a kit build, as you can adapt and modify as you build......

I may be wrong, but I think the Wots Wot cowl is longer? Might be worth looking into if it's a straight swap/ 

 

Edited By Percy Verance on 18/01/2019 19:21:00

Braddock, VC18/01/2019 20:15:33
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1585 forum posts
58 photos

Personally I think you'd be better off with the 55 AX, the laser is much heavier and that weight is going to be even further forward than the 2 stroke (fwiw 55 ax with silencer is about 520 grammes, laser 80 with silencer 719 gm, at least mine is.), this forward weight will probably need ballast at the rear to balance.

I'm always of the opinion that lighter planes fly better and land slower, a point you need to consider given the usual fragility of the u/c mounting on artf (and on the chris foss artb kit one as well)

I have a laser 80 and the only plane it was really at home in was a flair fokker D7 where the weight precluded any additional ballast.

Just a personal opinion.

Edited By Braddock, VC on 18/01/2019 20:51:26

Glenn Stevenson19/01/2019 07:55:02
19 forum posts

Thanks for the replies, I had an acrowot with an OS70fs some time back that was a lovely flier so I may go that way again, seems a shame not to use this laser though. It does look like it wont balance too well. I have a 2 stroke acrowot (sc52) that goes very well but the four stroke sound is much nicer!

Glenn

gangster19/01/2019 08:13:04
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915 forum posts
16 photos

Check out the RCME review of the artf acrowot. I am pretty sure it required a lot of weight to balance. That was with an asp fs70. Mine needed the same although I have seen others with 2s 52 or 55 size engines that balance just fine. Whilst I have no idea what’s going on there or what changed if yours is of the tail heavy variety the laser a bit further forward could help

Jon - Laser Engines19/01/2019 09:10:27
4506 forum posts
164 photos

In fairness, the artf acro wot is not the best suited to our 80 due to the short mounting length. As has already been mentioned the kit version was much more flexible and in that the 80 works fine. We normally recommend our 70 for the artf version as its plenty of power and fits without major modification.

If you want a home for your 80 but dont want to spend a fortune look for the seagull isport 10cc. We have several customers flying this model with the 80 and they all are very pleased with its performance. I am told they also balance without lead when using the 80, which is nice if you care about such things

Braddock, VC19/01/2019 13:00:53
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1585 forum posts
58 photos

I'd forgotten about the isport, trouble is I can't remember if I had a laser 70 or laser 80 installed in it. Lovely flier though and about the only plane in my living memory that I can say lost due to radio, fault in my futaba 10 tx, now scrapped.

I bought my isport from the now defunct ashford model supplies as a second hand airframe complete with servos, best bargain of my life, too.

Bob Cotsford19/01/2019 14:04:42
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7759 forum posts
431 photos

Is the AW cowl shorter than the WotsWot? I squeezed an 80 into my WW with less than 10mm of gap between the spinner and cowl, though it did need a couple of oz of lead in the tail to bring the balance point back where the model flew as I wanted.

wotswot_laser_80_fit[1].jpg

Chris Walby19/01/2019 21:54:00
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894 forum posts
213 photos

I am with Jon and fitted my 70 into the Acrowot, (no lead and C of G spot on) and it flies very well (even one of our club instructors said it flew on rails).

IMHO If you are going to fit the 80 then push it as far back as you can, even if the bulkhead needs a bit of altering it will be worth it in the log run. If the 80 is forward it will need lead (not a problem in its self, but it will increase wing loading and change the flick ability that the 70 has. Stick the RX battery aft and you should get C of G and no lead.

I was very tempted with the iSport/80 combination, but agreed with Jon that its too much for the 70 to pull around the sky, but the 80 would be just right.

Bob, The WW is a lot more draggy and most likely a lower wing loading so needs bigger lump (club member has a 90 in his!). Though had crossed my mind, but again my 70 would not do it justice.

Whatever you decide, can you post your build for the rest of the Laser appreciation society wink

Ron Gray19/01/2019 21:58:56
1388 forum posts
350 photos

Rather than adding tailweight, think about mounting the rudder and elevator servos at the back.

Phil Francis20/01/2019 21:33:17
53 forum posts
11 photos

I have OS 95 in mine and a 5 cell pack under the tank. They do vary in weight distribution.

Paul james 821/02/2019 17:08:49
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126 forum posts
23 photos

I'm about to start putting a new ARTF Acrowot together and I have a tidy rebuilt Laser 75 that I'm thinking about fitting. I have a scruffy old Acrowot with a Saito 82 up front but that has a great lump of lead as well to balance it so I guess the 75 will be fine?

Chris Walby21/02/2019 17:48:34
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894 forum posts
213 photos

Hi Pj8,

Not sure the difference in weight between the 70 and 75 but it can't be much!

I put a little lead on the engine as the battery was on C of G for the first few flights. It needed a little elevator when inverted so I used the battery cover as access, put the battery in there and lost the lead.

Mine even comes out slightly light on AUW, flies very slowly + bats about very nicely.

Good luck and keep us posted on your build wink

Jon - Laser Engines21/02/2019 20:31:24
4506 forum posts
164 photos

The old 75 is heavier than our current 80 and the same physical size. You may find it difficult to fit it in the shorter cowl on the ARTF version but its worth a go. Certainly power will not be a problem

Tim Flyer17/03/2019 17:42:47
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955 forum posts
158 photos

Hi all just an update more progress this’s weekend . Here is the side scoop I formed from Aluminium scrap sheet . I will need to do a bit more painting to finish blending it in d2f32cb0-6188-4ef7-a197-972d3b98cf48.jpeg

Edited By Tim Flyer on 17/03/2019 17:50:49

Tim Flyer17/03/2019 17:47:45
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955 forum posts
158 photos

Here is my exhaust with the plane inverted I’m using a jubilee clip bolted to a home made aluminium bracket on the end to clamp it . When the plane is finished I will insert a high temp silicone sleeve in the clamp to allow a bit of give and reduce vibration. 96eb7edc-f1ec-4bba-87db-8658c61ca5bf.jpeg

Edited By Tim Flyer on 17/03/2019 17:48:31

Paul james 818/03/2019 06:28:57
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126 forum posts
23 photos
Posted by Tim Flyer on 17/03/2019 17:47:45:

Here is my exhaust with the plane inverted I’m using a jubilee clip bolted to a home made aluminium bracket on the end to clamp it . When the plane is finished I will insert a high temp silicone sleeve in the clamp to allow a bit of give and reduce vibration. 96eb7edc-f1ec-4bba-87db-8658c61ca5bf.jpeg

Edited By Tim Flyer on 17/03/2019 17:48:31

 

That is a pretty tight bend in the flexi tube right up near the head, would it not have been possible to fit a rigid bend at that point then flexible from there? Got to start on mine soon so will be interested to hear how you get on with yours before deciding on exhaust fitting.

Edited By Paul james 8 on 18/03/2019 06:30:39

Tim Flyer18/03/2019 09:32:58
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955 forum posts
158 photos

The bend is not actually very tight . Unfortunately it appears that way in the photo as the outside of the bend us not visible. b6187cbf-5e11-44db-b45b-5e101f1bfc1a.jpegThe exhaust will add very little back pressure at all , and I expect full performance . This photograph is slightly better.

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