J D 8 Posted January 14, 2020 Share Posted January 14, 2020 And all engines were still running when he landed, mind you with that may would you even notice if one or two dropped out ? Just an amazing model. Link to comment Share on other sites More sharing options...
Nigel R Posted January 14, 2020 Share Posted January 14, 2020 12 Watching him start them, those are some well set up engines, much respect. Link to comment Share on other sites More sharing options...
Nigel R Posted January 14, 2020 Share Posted January 14, 2020 "So im looking for small four stroke engines, if anyone has any ideas" There is usually a small but steady supply of the pre-surpass OS 40s available on the popular auction site. They seem to go for a fair bit less cash than the surpass versions, or the later 48. Link to comment Share on other sites More sharing options...
Manish Chandrayan Posted January 14, 2020 Share Posted January 14, 2020 Saito still makes the 30 and 40. Or if you can find the ASP/Magnum/SC 30's Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted January 14, 2020 Share Posted January 14, 2020 It's certainly a video to show to the electrofanatic ICphobics... Dare I mention the practicality of on-board glows in such an installation? Link to comment Share on other sites More sharing options...
Jon H Posted January 14, 2020 Author Share Posted January 14, 2020 Posted by Martin Harris on 14/01/2020 13:19:23: It's certainly a video to show to the electrofanatic ICphobics... Dare I mention the practicality of on-board glows in such an installation? Only in the interest of getting them started Nigel, in other videos i have seen the chap starts each engine in turn and gives it a quick tune/power test. Once satisfied he turns it off and moves down the line. That way, when he comes to his display slot all of the engines are ready to go having been set earlier on. Link to comment Share on other sites More sharing options...
SR 71 Posted January 14, 2020 Share Posted January 14, 2020 REF, the Laser exhaust, that was one of the reasons i wanted to fit Lasers, so small neat and tidy, really dont want big lumps of exhaust sticking out Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted January 16, 2020 Share Posted January 16, 2020 Earlier in the thread there was considerable discussion of the chicken hopper fuel system. I took my plans for my Tempest to Jon while deciding on the purchase of a 200v a few years ago and he thought I'd get away with the fuel tanks which, due to structural considerations and the very short nose, are not practical to lower. Now that things are progressing again and reading informed comment on other installations from Jon, I'm reconsidering the wisdom of "getting away with it". Installing a chicken hopper system on a twin seems horrendously complex and I'm wondering whether the system illustrated below would work so perhaps anyone seeing a problem with it could comment? My initial concern would be that maybe one of the red tanks would not fill properly - and am I right in assuming that the suction involved in pulling fuel up from the lower tank should lower the fuel head seen by the engines? It seems a much simpler solution if it will work...I have some T pieces on order so that I can do some practical testing. Link to comment Share on other sites More sharing options...
Ron Gray Posted January 16, 2020 Share Posted January 16, 2020 I can't really see the logic of the design as shown in the sketch. If the 2 tanks shown at the top are feeding the engine then it will cut out as there is no vent to those tanks. Plus when you fill the top 2 they will overflow into the bottom one which will fill but it will not be able to supply fuel to the top 2. If you invert the tanks, so 2 at the bottom and fit them as per the chicken hopper plumbing then it will work and TBH the work involved is not that much. Can't you just put the engine in upright? or isn't there cowl room to do that? I was lucky with my Bearcat installation that allowed me to do just that. Link to comment Share on other sites More sharing options...
Jon H Posted January 16, 2020 Author Share Posted January 16, 2020 Having slept since we spoke Martin i have zero recollection of our discussion! In any case, it looks like you might just about get away with it but i would suggest a tank change you can squeeze a little more capacity out of this **LINK** in more or less the same space. That said, the plate the tanks currently sit on looks pretty easy to remove. You could then lower the tank, notch the leading edge of the wing slightly and it would be all good. You might even get away with slinging the tank/s under that plate and then you only have to notch the wing. I did the exact same on my hurricane recently and its worked out nicely as it also means i can run the cooling tunnel under the tanks. Not that cooling air exit will be a problem for a tempest. As long as you can replace the moved structure with a ply box it will be plenty strong enough. Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted January 16, 2020 Share Posted January 16, 2020 The problem with removing the floor is that the tank bay overlaps the wing fixing plate for the front wing pegs. The logic is that you fill the top tanks which, once they Ooverflow, spill into the lower tank. All venting is through the vent from the bottom tank which would be arranged to provide the "Laser" forward facing vent. As the top tanks supply the carbs, fuel is drawn from the bottom tank as the fuel is pulled while the tank vents. Link to comment Share on other sites More sharing options...
Nigel R Posted January 16, 2020 Share Posted January 16, 2020 "perhaps anyone seeing a problem with it could comment" I presume the carbs are level with the centre of the lower tank? If so, it will be exactly like having one tank a long way up - you simply have two tanks linked by a thin pipe, the fluid head hasn't been altered. The chicken hopper setup provides a pressure neutral lower tank. For a V twin, surely the only added complexity is that you need two clunk lines in the small tank? Link to comment Share on other sites More sharing options...
Steve Dunne Posted January 16, 2020 Share Posted January 16, 2020 For what it's worth... 1 I don't think that the fuel head problem would be resolved at all - the syphoning and leaking issues will remain. You still need to have the feed tank on the same level as the carburetter. 2 I don't think that carburetter suction will provide enough suction power to raise fuel from the lower tank. The carb usually provides only air suction against against a neutral head - i.e. the tank is on the same level. On my own chicken hopper installation (which works very well on my Spitfire) I cannot empty the lower tank by using the electric pump to suck out fuel via the upper tank. I have to invert the Spitfire to drain the bottom tank via the spill tube.. 3 There is nothing to balance the suction fuel head in the two tanks. I'm sorry to be the gainsayer, but I think your configuration, though ingenious, will not help you at all. Steve. Link to comment Share on other sites More sharing options...
Jon H Posted January 16, 2020 Author Share Posted January 16, 2020 Posted by Martin Harris on 16/01/2020 16:01:19: The problem with removing the floor is that the tank bay overlaps the wing fixing plate for the front wing pegs. Can the wing dowel former not be tied to the side frames with fishplates on the outside? It could also be braced internally if the tank you choose is narrower than the fuselage. Once the tanks are in you can add another plate above/below them to box them in and this will take the loads the original plate would have seen. I had to do this on the hurricane as well as i removed more or less all of the wing dowel former as you can see below. Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted January 16, 2020 Share Posted January 16, 2020 After some further thought, the effect - if it works - would actually raise the effective fuel head while the bottom tank was emptying and then reduce it as the top tanks empty. The carbs are at the level of the tank floor. Edited By Martin Harris on 16/01/2020 16:55:24 Link to comment Share on other sites More sharing options...
Jon H Posted January 16, 2020 Author Share Posted January 16, 2020 Posted by Ron Gray on 16/01/2020 14:03:37: Looking good Ron Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted January 16, 2020 Share Posted January 16, 2020 Posted by Jon - Laser Engines on 16/01/2020 15:00:08: Having slept since we spoke Martin i have zero recollection of our discussion! In any case, it looks like you might just about get away with it but i would suggest a tank change you can squeeze a little more capacity out of this **LINK** in more or less the same space. Sorry - missed the link when I read your reply on my mobile at the field. Interesting thought - would 16 oz be sufficient? My original intention was to use 2 11 oz SLEC tanks which you seemed to endorse at the time - although I don't recall specifically discussing duration. Link to comment Share on other sites More sharing options...
Ron Gray Posted January 16, 2020 Share Posted January 16, 2020 Posted by Jon - Laser Engines on 16/01/2020 16:40:13: Posted by Ron Gray on 16/01/2020 14:03:37: Looking good Ron Thanks Jon, will be putting up a mini thread on the build soon. Link to comment Share on other sites More sharing options...
Jon H Posted January 16, 2020 Author Share Posted January 16, 2020 Posted by Martin Harris on 16/01/2020 16:54:09: Posted by Jon - Laser Engines on 16/01/2020 15:00:08: Having slept since we spoke Martin i have zero recollection of our discussion! In any case, it looks like you might just about get away with it but i would suggest a tank change you can squeeze a little more capacity out of this **LINK** in more or less the same space. Sorry - missed the link when I read your reply on my mobile at the field. Interesting thought - would 16 oz be sufficient? My original intention was to use 2 11 oz SLEC tanks which you seemed to endorse at the time - although I don't recall specifically discussing duration. a 240v will run for 10 minutes at 3/4 throttle on 14oz so the 200 should be fine on 16. A 10-12 minute flight should not pose too many problems. Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted January 22, 2020 Share Posted January 22, 2020 I've got hold of one of the tanks you linked to Jon and it should be just about perfect. I'll install dual clunks and the filler in the bung and add a fitting for the vent in the top. Just for clarification with the vertical orientation of the carbs, I assume that the centre of the spraybar/inlet tract is the ideal target height for the mid tank position? Edited By Martin Harris on 22/01/2020 13:45:04 Link to comment Share on other sites More sharing options...
Jon H Posted January 22, 2020 Author Share Posted January 22, 2020 Posted by Martin Harris on 22/01/2020 13:44:06: I've got hold of one of the tanks you linked to Jon and it should be just about perfect. I'll install dual clunks and the filler in the bung and add a fitting for the vent in the top. Just for clarification with the vertical orientation of the carbs, I assume that the centre of the spraybar/inlet tract is the ideal target height for the mid tank position? Edited By Martin Harris on 22/01/2020 13:45:04 I tend to shoot for top of the tank, that way all of the fuel is below the carb all of the time so you dont get a change in fuel head like you would if it crosses the mid point. There is some wiggle room but i always aim for the top if i can Link to comment Share on other sites More sharing options...
Gary Spicer 1 Posted March 20, 2020 Share Posted March 20, 2020 Hi Jon Please can you confirm the thread/pitch for the prop nuts on my 2020 laser 70 and Laser 180 as I want to get a couple of domed nuts for them from Just Engines. I know most probably metric but just want to be sure! Thanks Link to comment Share on other sites More sharing options...
Jon H Posted March 21, 2020 Author Share Posted March 21, 2020 1/4x28 and M10x1.5 Link to comment Share on other sites More sharing options...
Gary Spicer 1 Posted March 21, 2020 Share Posted March 21, 2020 Thanks Jon for the info. Just curious....is there any advantage in having 1.5 pitch over say a fine 1.25 metric pitch on the 180? My old imperial laser 180 has a much finer thread pitch on the crank. Thanks Link to comment Share on other sites More sharing options...
Jon H Posted March 21, 2020 Author Share Posted March 21, 2020 not sure, i was still at school when they designed it! Older 180's had 3/8x24 cranks so the thread was quite fine. Link to comment Share on other sites More sharing options...
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