mike skingle Posted August 26, 2021 Share Posted August 26, 2021 I just thought I'd start a thread for the Laser 160 inline twin. I received the engine but had to have hand surgery soon after so things have been a bit delayed. So the plan is to fit the engine into a YT international P51D mustang 72inch wingspan. I managed to get hold of one that's seen several incarnations with a fair amount of modifications. Mainly to the firewall which in December most of it was removed in anticipation of the new engine. The plan is to completely enclose the engine, cooling through the chin intake with the hot air coming out the back of the belly radiator fairing. Quote Link to comment Share on other sites More sharing options...
mike skingle Posted August 26, 2021 Author Share Posted August 26, 2021 There's the engine mounted it was on a 5mm ply which made planning and modification easier. Removong the top section of the front fuselage made getting the 18mm thick bulkhead alot easier. The ducting was made in sections out of a mixture of balsa and fibreglass. Quote Link to comment Share on other sites More sharing options...
mike skingle Posted August 26, 2021 Author Share Posted August 26, 2021 Sorry my photos are abit out of sync. These one show the top section of the front fuselage cut away as you can see it will be covered by the cowl when it goes on. The next one is the exit of the cooling air duct. The last one shows the ducting through the fuselage. At the moment this is abit of a frankinstein but it's move of an attempt to find out how much cooling air is needed. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted August 27, 2021 Share Posted August 27, 2021 Is it taking air from the rear carb from a potentially different pressure area? If so, might it lead to some odd tuning quirks between ground runs and aerial use? Just wondering out loud really... Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted August 27, 2021 Share Posted August 27, 2021 I had problems with the running of my 200i in my Sportster but fitting intake tubes to the carbs and running those to inside the fuse has cured the problem. Glad to see this thread as I’m about to start the conversion of my BNIB YT P51 for my 160i so this will help me a lot. Quote Link to comment Share on other sites More sharing options...
Jon H Posted August 27, 2021 Share Posted August 27, 2021 Mike popped in to the factory yesterday and i took a look the Mustang. The setup looks good and we tested it with a very light blow i the front of the cowl was immediately felt at the back where the air exits. It will be interesting to see if the rear carb has issues as Ron's did, but that is the point of testing. Personally i was a little surprised they cropped up on Rons model, but this is why we test stuff. If everyone has the same problem we can recommend a fix, but until then each model should be treated as a blank canvas so we can establish trends so i would ask that engines are fitted as supplied without the carb tubes, just so we can isolate if it is a common problem or something specific to the sportster installation. Another thing to note now we are getting into warbird territory is that super tight cooling like this with a venturi exit will not work on the ground. Unless it has 40 or 50mph of slipstream running over the model it simply wont work so prolonged ground testing is not recommended. If the engine is overheating on the ground that is not a sign that the cooling system is deficient, just that it is not working due to sitting still. Full size WWII era aircraft suffer from this all the time and i have seen more than a few boil over at airshow's on hot days. Quote Link to comment Share on other sites More sharing options...
mike skingle Posted August 27, 2021 Author Share Posted August 27, 2021 Jon I've managed to lower the tank and am in the process of smoothing out the bulkhead to ducting connection. My initial thoughts on cooling were chin intake down the left side and across and out the lower right side of the bulkhead. When Ron had the problems with the carburettors and had to add the tubes i tried to work out how to make the flow of air smooth as I assume that there is some turbulence in the cowl which varies depending on the speed of the airflow. Any how after many hours of thought several watches of Jons video and with no other examples I'd start at best guess. And here it is. The extra holes in the bulkhead will be blocked up. Any other suggestion or pictures of what you guys with your 200 inlines have done would be helpful. Quote Link to comment Share on other sites More sharing options...
Ted Khinsoe Posted August 29, 2021 Share Posted August 29, 2021 Good to see another in progress. Mike, your situation is virtually the opposite of mine. I have an engine with acres of space around it. Your solution will be very helpful when I get mine in the Tiger Moth. Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted August 29, 2021 Share Posted August 29, 2021 Feeding the hot air out through the fuse ducting could, I think, prevent the erratic running I had with my Sportster. Unfortunately there isn’t the space to do that in the Sportster fuse but the carb intake tubes work incredibly well and have a side benefit in making the engine quite a bit quieter too! The hot air in the Sportster just hits the bulkhead and exits from the bottom of the cowl but the ducting of the intake (see my Sportster thread) which is much the same as yours does work and there have been no signs of one pot overheating. When I get onto my P51 I think I may well copy your idea of a 3D printed intake duct but I will glass cloth it as I don’t want to risk it deforming with the heat from the engine. The one in my Sportster is formed from balsa and lite ply which, to be fair, hasn’t suffered any detrimental effects after what must now in excess of 1 ½ hours flying time. I can’t see it in your photos but I’m assuming that the hot air duct exits through the belly cooler duct rear flap? Quote Link to comment Share on other sites More sharing options...
Jon H Posted August 29, 2021 Share Posted August 29, 2021 That tank could still come down a bit Mike. I would drop it onto that line on the fuselage where the vertical wing dowel former and radiused wing cutout meet. That will give the best chance for success. Also please do not just copy the work of others. I am interested to see the various different approaches and we need to see which is the most effective and repeatable. As i mentioned before its possible you do not need Ron's pipes, but if you do and eveyone else needs them to we can see that something needs to go in the instructions. IF you dont need them, but fit them anyway and performance is fine, it gives a false impression of the requirements of the engine in its natural habitat. Generally i cannot see too much wrong with your setup. its exactly what i had in mind and i believe it will work just fine when the model is up and flying. Its a shame i do not have a suitable yt model myself as i would get it on the bench right away. My only suitable warbirds a long build kits and ARTF's aint gonna cut it ? Quote Link to comment Share on other sites More sharing options...
mike skingle Posted August 29, 2021 Author Share Posted August 29, 2021 Some progress today lowering the fuel tank cutting a section from the leading edge and boxing it in again. Unfortunately due to the ducting the tank is off the centre line with the result being one of the wheel wells is in the way restricting how much the tank can be lowered without taking all the ducting out. (Sorry Jon ) I'm not going to be able to get the tank any lower Without alot of work. currently it's 50mm x 65mm cross section at the narrowest point. Anyway this is proof of concept and I just need a starting point ideally soon. Ron when you do your yt P51 i suggest a tank no wider that 30mm either side of centre line and it will fit nicely between the wheel wells ? Ron I'm afraid I haven't done any 3D printing it might have made things a bit quicker. The duct is balsa and fibreglass. I think Ted on page 11 on the 200 inline thread printed. My ducting only goes up as far as the servo tray if it needs biger ducting then I'll take it out and start again. Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted August 29, 2021 Share Posted August 29, 2021 You are correct Mike, I was getting my in-line twin threads crossed (3D printing!) 30mm wide tank, that is one narrow tank! Quote Link to comment Share on other sites More sharing options...
mike skingle Posted August 29, 2021 Author Share Posted August 29, 2021 Ron the tank can be 60mm wide as the ribs inboard of the wheel wells are about 30mm from the centre ribs Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted August 29, 2021 Share Posted August 29, 2021 30mm each side (just re-read your earlier post ?) Quote Link to comment Share on other sites More sharing options...
Jon H Posted August 29, 2021 Share Posted August 29, 2021 Ah yes the wheel well. How far down does the wheel sit in the plastic well? It likely you could remove the plastic but not foul the wheel. Quote Link to comment Share on other sites More sharing options...
mike skingle Posted October 22, 2021 Author Share Posted October 22, 2021 Wheel wells came out when I put the retracts in the ones that came with it had been well used and twisted. I used the old oleos with some new electric retract units. I managed to get some of those traxx onboard glow leads and wired the plugs on 2 separate curcuits. The engine was test run and would start only on the front cylinder when both glow plugs were attached to the battery. Both glow plugs when tested worked fine they were New OS type F . Applying the battery to one plug at a time got both running and the engine ran very smoothly. The model was flown twice with the cowl off to balance and trim it. The last flight was with the cowl on and the engine performed faultlessly throught the flight and it sounded great ?. Unfortunately on the landing rollout just before it stopped the axle on one wheel came off and the retract pin bent so we had to stop. The rain follwed about 30minutes after. If I can work out how to upload the videos then you can see for yourself. All in all a good start. Hopefully the ground test run will upload. 20211018_111854.mp4 1 Quote Link to comment Share on other sites More sharing options...
mike skingle Posted October 22, 2021 Author Share Posted October 22, 2021 YouCut_20211022_214443941.mp4 2 hours ago, mike skingle said: Wheel wells came out when I put the retracts in the ones that came with it had been well used and twisted. I used the old oleos with some new electric retract units. I managed to get some of those traxx onboard glow leads and wired the plugs on 2 separate curcuits. The engine was test run and would start only on the front cylinder when both glow plugs were attached to the battery. Both glow plugs when tested worked fine they were New OS type F . Applying the battery to one plug at a time got both running and the engine ran very smoothly. The model was flown twice with the cowl off to balance and trim it. The last flight was with the cowl on and the engine performed faultlessly throught the flight and it sounded great ?. Unfortunately on the landing rollout just before it stopped the axle on one wheel came off and the retract pin bent so we had to stop. The rain follwed about 30minutes after. If I can work out how to upload the videos then you can see for yourself. All in all a good start. Hopefully the ground test run will upload. 20211018_111854.mp4 2 hours ago, mike skingle said: Wheel wells came out when I put the retracts in the ones that came with it had been well used and twisted. I used the old oleos with some new electric retract units. I managed to get some of those traxx onboard glow leads and wired the plugs on 2 separate curcuits. The engine was test run and would start only on the front cylinder when both glow plugs were attached to the battery. Both glow plugs when tested worked fine they were New OS type F . Applying the battery to one plug at a time got both running and the engine ran very smoothly. The model was flown twice with the cowl off to balance and trim it. The last flight was with the cowl on and the engine performed faultlessly throught the flight and it sounded great ?. Unfortunately on the landing rollout just before it stopped the axle on one wheel came off and the retract pin bent so we had to stop. The rain follwed about 30minutes after. If I can work out how to upload the videos then you can see for yourself. All in all a good start. Hopefully the ground test run will upload. 20211018_111854.mp4 1 Quote Link to comment Share on other sites More sharing options...
mike skingle Posted October 22, 2021 Author Share Posted October 22, 2021 YouCut_20211022_214911441.mp4 1 Quote Link to comment Share on other sites More sharing options...
mike skingle Posted October 22, 2021 Author Share Posted October 22, 2021 The last flight with the cowl on. Sorry for the poor quality it's the only way to get the file small enough. YouCut_20211022_231652089.mp4 2 Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted October 23, 2021 Share Posted October 23, 2021 Very nice Mike, seems well matched to airframe. What prop were you using? Quote Link to comment Share on other sites More sharing options...
mike skingle Posted October 23, 2021 Author Share Posted October 23, 2021 Jon advised a 16x8 so I put a grey graupner 16x8 on it. I think once it's run a bit I'll try something slightly bigger but most of the flight was around half throttle. Ron is your YT Mustang the P51B or P51D as I found that the manual has the CG at 137mm and 157mm respectively and I seam to recall that the instructions were wrong i think on the P51D. I hope to accurately measure the CG but I think it's closer to 137mm. To get it at 157mm I would have had to put 300grams of lead in the tail? just something to consider if your planning your build. Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted October 23, 2021 Share Posted October 23, 2021 Mine’s the ‘D’ Mike so very interested in your CG measurement! Quote Link to comment Share on other sites More sharing options...
mike skingle Posted October 23, 2021 Author Share Posted October 23, 2021 7 hours ago, Ron Gray said: Mine’s the ‘D’ Mike so very interested in your CG measurement! Using the finger method it was around the 135-140mm from the front of the wing. Quote Link to comment Share on other sites More sharing options...
Jon H Posted October 23, 2021 Share Posted October 23, 2021 sounds lovely but its happier without the cowl apparently. Its subtle, but it just sounds happier without it. Its probably temperature related. As you say, 16x8 for initial flights is great with 17x8 being just fine after an hour or so in the air. On c/g, folk slate ESM for bad c/g but i have always found them to be ok. Where it all falls over is the excessive rates the recommend. Dial them down and its all good ? At some stage Mike i will have to shoot up to your field and take a look. Assuming thats all ok with the powers that be Quote Link to comment Share on other sites More sharing options...
mike skingle Posted October 23, 2021 Author Share Posted October 23, 2021 I think on this occasion ESM misprinted the CG. I'm sure coming up to the field will be fine. I'll give you a call next time I'm going. I haven't actually touched the tuning it started easily and seemed to run with great throttle response. I didn't particularly want it screaming away on its first flights, and half throttle was more than enough. The undercarriage is all fixed now we just need some good weather to fly it. Quote Link to comment Share on other sites More sharing options...
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