Glenn Stevenson Posted January 18, 2019 Share Posted January 18, 2019 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 Quote Link to comment Share on other sites More sharing options...
Jon H Posted January 18, 2019 Share Posted January 18, 2019 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 Quote Link to comment Share on other sites More sharing options...
alex nicol Posted January 18, 2019 Share Posted January 18, 2019 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 Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 18, 2019 Share Posted January 18, 2019 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted January 18, 2019 Share Posted January 18, 2019 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 Quote Link to comment Share on other sites More sharing options...
Glenn Stevenson Posted January 19, 2019 Author Share Posted January 19, 2019 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 Quote Link to comment Share on other sites More sharing options...
gangster Posted January 19, 2019 Share Posted January 19, 2019 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 Quote Link to comment Share on other sites More sharing options...
Jon H Posted January 19, 2019 Share Posted January 19, 2019 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 Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted January 19, 2019 Share Posted January 19, 2019 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. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted January 19, 2019 Share Posted January 19, 2019 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. Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted January 19, 2019 Share Posted January 19, 2019 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 Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted January 19, 2019 Share Posted January 19, 2019 Rather than adding tailweight, think about mounting the rudder and elevator servos at the back. Quote Link to comment Share on other sites More sharing options...
Phil Francis Posted January 20, 2019 Share Posted January 20, 2019 I have OS 95 in mine and a 5 cell pack under the tank. They do vary in weight distribution. Quote Link to comment Share on other sites More sharing options...
Paul james 8 Posted February 21, 2019 Share Posted February 21, 2019 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? Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted February 21, 2019 Share Posted February 21, 2019 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 Quote Link to comment Share on other sites More sharing options...
Jon H Posted February 21, 2019 Share Posted February 21, 2019 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 Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted March 17, 2019 Share Posted March 17, 2019 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 Edited By Tim Flyer on 17/03/2019 17:50:49 Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted March 17, 2019 Share Posted March 17, 2019 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. Edited By Tim Flyer on 17/03/2019 17:48:31 Quote Link to comment Share on other sites More sharing options...
Paul james 8 Posted March 18, 2019 Share Posted March 18, 2019 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. 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 Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted March 18, 2019 Share Posted March 18, 2019 The bend is not actually very tight . Unfortunately it appears that way in the photo as the outside of the bend us not visible. The exhaust will add very little back pressure at all , and I expect full performance . This photograph is slightly better. Quote Link to comment Share on other sites More sharing options...
GrahamWh Posted March 18, 2019 Share Posted March 18, 2019 Tim is there a danger that at high speed a venturi effect around the carb intake side scoop could drop air pressure to the carb? Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted March 18, 2019 Share Posted March 18, 2019 Hi Graham I don’t think so. It would need really massive speed if anything. I have a similar arrangement with the carb in my LA7 where the carb is actually in the main cowl air outlet. I also have the carb right in front of the wing and directly in the airstream on on Wot4 powered with a laser 80. The carb comes out right into the airstream and it is absolutely fine. I guess if one were at massive speed there could be some turbulence effects but I have found most carbs fine being in airflow in fact it’s much better than them getting hot! Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted March 18, 2019 Share Posted March 18, 2019 This one I fly a lot has carb on laser 80 right in the airstream. Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted April 8, 2019 Share Posted April 8, 2019 Here is the cowl now fitted. I put a small aluminium scoop on the bottom to cover the bulky exhaust bracket and for aesthetics. I also added a bit of internal baffling so the air doesn’t bypass the cooling fins and be drawn out of the bottom exhaust scoop . Here is the front side view . Hopefully I will get the rest finished and maiden fly it this weekend 😊 Quote Link to comment Share on other sites More sharing options...
GrahamWh Posted April 8, 2019 Share Posted April 8, 2019 Very neat work Tim and thanks for answering about the airflow around the carb as it is something I have often thought about in the past. Quote Link to comment Share on other sites More sharing options...
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