Chris Walby Posted November 3, 2020 Share Posted November 3, 2020 Looking nice, well actually a lot more than nice, dammed gorgeous ....so next on the thread is what airframes suit a 160 or 200 inline twin? Nice one there Jon Edited By Chris Walby on 03/11/2020 15:25:04 Quote Link to comment Share on other sites More sharing options...
Nigel R Posted November 3, 2020 Share Posted November 3, 2020 Posted by Jon - Laser Engines on 03/11/2020 14:43:21: Anyway, here is is.. That very much looks fabulous video on youtube please! Quote Link to comment Share on other sites More sharing options...
David P Williams Posted November 3, 2020 Share Posted November 3, 2020 Excellent - just need one a bit bigger for the TopFlite 1/5 scale Mustang kit that's in the loft........ Quote Link to comment Share on other sites More sharing options...
alan p Posted November 3, 2020 Share Posted November 3, 2020 Looking through engineers eyes that does look bloody good, does the crank case split just in front of the second cylinder?. Using the oft quote ( If it looks right -it is right) Well done Jon Quote Link to comment Share on other sites More sharing options...
Eric Robson Posted November 3, 2020 Share Posted November 3, 2020 Nice engine for a D.H.9 . Quote Link to comment Share on other sites More sharing options...
Chris Berry Posted November 3, 2020 Share Posted November 3, 2020 Ooh, thats nice. I've got a 200v and 300v, so an inline version for a warbird with suitable cooling would be lovely. How long is the engine Jon? Cheers Quote Link to comment Share on other sites More sharing options...
alan p Posted November 3, 2020 Share Posted November 3, 2020 Hi Chris Will it fit the Hurricane???? Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted November 3, 2020 Share Posted November 3, 2020 Looks good is this a 360 deg twin or have you set the crank at 270 deg to give an uneven firing but maybe less vibration? Quote Link to comment Share on other sites More sharing options...
Jon H Posted November 3, 2020 Author Share Posted November 3, 2020 To answer the questions David, yep, 5th scale Mustang is on my list of models to build as is 5th scale Spitfire and P40. a 60cc version would do these models no problem i think you would agree? So, if you can do me a favour and grab your Mustang plan, then measure back from the spinner backplate and see how far back you can go before you need to completely reinvent the wheel and let me know the dimension. I measured my 5th scale P51 and think 280mm is in the ballpark for total engine length? Alan, crankcase in 3 bits! All sorts of giblets inside as well. Not sure about the Hurricane, if you mean the seagull one then no, not without major mods. If you dont mind hacking it about it can be made to fit anything! Eric, yep anything with an inline engine. A DH9 had a monster prop though if i recall, might need a gearbox Chris B, 230mm prop driver to firewall. I used the DB and Mick Reeves Spitfires as benchmarks and found 230 was the limit before it got daft. it should also fit 1/4 tiger moths etc at this length and will fit 1/4 scale stampes with no real issues. But, as i said before the model should be built around the engine and if someone does not want to do that its fine, the 180 single will do just in fine in its place. But, if you want the twin, there will be a bit more work involved but i dont see it as an issue. Frank, 360. I was going to go the other way for balance but wanted to try this first for sound reasons and for giving a nice even fire. As it runs smoothly enough as is im leaving well enough alone! Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted November 3, 2020 Share Posted November 3, 2020 Alan P I - I don't have a Hurricane any more following a terminal vertical decent. As Jon has mentioned these engines are for fully built models where the bulkhead can be built easily to suit the engine layout. Knowing Jon's attention to detail I am sure he has some really good ideas as to which designs can be used, we just need to coax the information into the public domain. Beat me to it PS - IMHO if you are considering the SG Hurricane, then don't, build from a plan that's known to fly well and fit the inline twin...win win ! Edited By Chris Walby on 03/11/2020 17:18:34 Quote Link to comment Share on other sites More sharing options...
David P Williams Posted November 3, 2020 Share Posted November 3, 2020 Jon - a 60cc version would be more than enough I would think. I'll dig the plan out of the loft tomorrow - I was going to go flying but a couple of deliveries that should have arrived today got put back to tomorrow. Flying Thursday before lockdown instead. Quote Link to comment Share on other sites More sharing options...
David P Williams Posted November 3, 2020 Share Posted November 3, 2020 Oops - I had read that the lockdown was from midnight on Thursday but it's 00.01 Thursday, so if I don't get out for a fly on Wednesday that's it for the winter probably. Oh well, lots of time to get back onto the Stearman.... Quote Link to comment Share on other sites More sharing options...
cymaz Posted November 3, 2020 Share Posted November 3, 2020 Jon, what is the thinking behind twin carbs with any of your multi engines? Quote Link to comment Share on other sites More sharing options...
Alan Hilton Posted November 3, 2020 Share Posted November 3, 2020 Hi Jon How do you see cooling the back pot ? An uncle of mine had a sunbeam in line twin motor bike which had rear cylinder cooling problems .He had an Ariel square four as well which was even worse .Im having back problems so I am having to review the size of models I am flying so I won’t be much use as a tester Alan Quote Link to comment Share on other sites More sharing options...
Jon H Posted November 3, 2020 Author Share Posted November 3, 2020 Posted by cymaz on 03/11/2020 17:39:38: Jon, what is the thinking behind twin carbs with any of your multi engines? Twin carbs offer better control over the mixture and you can tune each cylinder so that its happy. This is better for reliability and performance. I had a saito 450 3 cylinder radial and it always ran no1 cylinder about right, no2 rich, and no 3 lean as lean can be. Their petrol fg84 suffered the same issue and there was an intake mod offered that made it better. You also have another level of failsafe as one carb may get dirt in it or something but the other will not so the engine will run on one cylinder. Often this is enough to limp back to the runway and i had this happen to me last year with the 300v in my P39. Debris in one carb, dropped to one cylinder right after takeoff but didnt stop completely. If you treat a twin as 2 engines (2 cylinders, 2 carbs, 2 tanks) there is a reliability advantage. All that said, beyond 2 carbs it does start to get a little complicated. Quote Link to comment Share on other sites More sharing options...
Jon H Posted November 3, 2020 Author Share Posted November 3, 2020 Posted by Alan Hilton on 03/11/2020 17:44:26: Hi Jon How do you see cooling the back pot ? An uncle of mine had a sunbeam in line twin motor bike which had rear cylinder cooling problems .He had an Ariel square four as well which was even worse .Im having back problems so I am having to review the size of models I am flying so I won’t be much use as a tester Alan Ok cooling... I do not expect it to be a problem...if its done right. However, just nailing it to a model and slapping a cowl on wont do and the engine will need to be carefully ducted and baffled to make it all work. In the case of a Spitfire or similar you will need to cut through the firewall and build a duct inside the fuselage to take the hot air out of the cowl and direct it somewhere else. On a Mustang its easy as the scale outlet can be used to exhaust the cooling air. It will be more involved than a single but its not going to be a total nightmare i dont think. Again, plan ahead, build the model round the engine. Quote Link to comment Share on other sites More sharing options...
Chris Berry Posted November 3, 2020 Share Posted November 3, 2020 Thanks Jon. Alan P may have been referring to a DB Hurricane which I have, still in its box. I think if built light and as you say, around the engine it might just do it. Would need the firewall moving back or significantly changing due to it being a short nose aircraft as plan at least. Quote Link to comment Share on other sites More sharing options...
cymaz Posted November 3, 2020 Share Posted November 3, 2020 Thanks Jon. Tuning an engine with a dual carb has always put me off a bit, as I don’t know the best way to go about it. I’m sure I’ve seen you tune your LA-7 at Wings and Wheels but I’m not entirely 100% Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted November 3, 2020 Share Posted November 3, 2020 Posted by cymaz on 03/11/2020 18:22:23: Thanks Jon. Tuning an engine with a dual carb has always put me off a bit, as I don’t know the best way to go about it. I’m sure I’ve seen you tune your LA-7 at Wings and Wheels but I’m not entirely 100% Cymaz, you are worrying unduly, tuning twin carbs on a model engine is fairly straight forward. It's more of an issue making sure both carbs open equally, but Laser have got that well covered on their V twins and the inline twin looks to use a similar system, whereas my old Vega flat twin has twin carbs where the throttle action is reversed on each side. Quote Link to comment Share on other sites More sharing options...
John Stainforth Posted November 3, 2020 Share Posted November 3, 2020 Jon, That looks like a really interesting development. It shouldn't be at all difficult to design scale models around that, e.g., the full-size V12's, like the Merlin, were very long engines. Is the performance about the same as the 200V? Quote Link to comment Share on other sites More sharing options...
kevin b Posted November 3, 2020 Share Posted November 3, 2020 Coooo. That's nice. What next Jon, one of these ? Quote Link to comment Share on other sites More sharing options...
Maurice Dyer Posted November 3, 2020 Share Posted November 3, 2020 More than anything: isn't it nice to have some forward looking modelling good news for a change ???. Maurice .😀 Quote Link to comment Share on other sites More sharing options...
Jon H Posted November 3, 2020 Author Share Posted November 3, 2020 Chris B, i dont think the 200 will be man enough for the DB Hurricane. I am building one myself and its a bit of a porker. Im sure it will fly with a 200, but it probably wont sparkle. I pondered which engine to use in mine for nearly 10 years! Im using a 240v for mine. Its not going to be overpowered but its a Hurricane so it will be fine. I wish i had a 40/50cc inline but not yet! Cymaz, yea dont worry about dual carbs. Its dead easy and i have a video somewhere of me setting one up. Its on the Laser youtube i think and i cant remember if its public or not. I will check and post the video tomorrow. John, performance is both better and worse than a 200v. Its actually been very interesting as the engine will not rev as fast as a 200 on small props, but handily beats it on large props. It will even swing a 20x8 apc with authority. If anyone already has a 180 or 200 from us the performance is in the same ballpark. The 160i really surprised me by matching a 180 on my test 20x6. A 160v wont do that. Kevin...no comment Quote Link to comment Share on other sites More sharing options...
David P Williams Posted November 4, 2020 Share Posted November 4, 2020 Hi Jon - I've retrieved the TopFlite P51 plan from the loft. Do these pics help? Let me know if you need any other pics or dimensions. Quote Link to comment Share on other sites More sharing options...
Jon H Posted November 4, 2020 Author Share Posted November 4, 2020 Yep that's perfect. At 280mm you would just slap another former in between f1 and 2 or, ideally, beef up f2 and drop it to the fuselage floor before building a box on the front of it to carry the engine. Either would become the new firewall and everything else in front you just chop off. Fit a cowl over the top and its a done deal. Looking closer you have a wooden cowl there so what i would do is make 2 new full depth F2's. One would be really beefy to carry the engine and the other thinner to form the back of the cowl. Build the model to the plan with the new formers installed back to back with a sawblade gap between them. Then you can sand the fuselage to profile and gently cut the front off between the formers and then use it as the wooden cowl. Or you could make a glass one using the wooden one as a pattern, or buy a 5th scale mustang cowl...lots of options Quote Link to comment Share on other sites More sharing options...
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