Low pass Pete Posted December 27, 2016 Share Posted December 27, 2016 Hi all Well Santa was good to me. A plan and a lovely pack of wood to boot. Mrs Low Pass has been a real trooper! Will keep you all posted on progress. I expect to use a 4 Stroke so some mods will be required to the plan. Best wishes to all fellow MB2017 builders. Peter Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 6, 2017 Author Share Posted January 6, 2017 I have now had time to take a look at the plan and have decided that the engine should be a 4 stroke. My final choice of power-plant is an OS62V 4 stroke which I have just ordered from Slough RC (best price by miles). If the engine is anything like the 95V it should be very economical to run (have a 95V in an old Hangar 9 P47 and it runs very well). Regards to all Peter Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted January 6, 2017 Share Posted January 6, 2017 Sounds good Pete, picture when it arrives John Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 7, 2017 Author Share Posted January 7, 2017 I have used the OS62 destined for my DB Sport and scale tiger Moth to show how the engine will fit to my rendition of Skywriter. F2 will have to be moved rearwards by approx. 2" But that is no problem as the original design does actually say place F2 according to engine size. I will leave the lower cowl open (as I did in Ballerina). This should make installation easier, especially regarding to the silencer which is somewhat different to an OS 52 or SC52. Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 7, 2017 Author Share Posted January 7, 2017 Regarding under-carriage. I have a set of dural legs that came from a Seagull Edge 540 which look ok to use as a base. Looking at the against the plan I will re-bend/modify and finish as close to the plan using Pete Millers approach. (that seems about right) Edited By Low pass Pete on 07/01/2017 15:52:34 Quote Link to comment Share on other sites More sharing options...
onetenor Posted January 7, 2017 Share Posted January 7, 2017 Don't forget to anneal the dural before bending Ask me how I know Quote Link to comment Share on other sites More sharing options...
Lucas Hofman Posted January 8, 2017 Share Posted January 8, 2017 Shiny and new! Glad someone else has started too! Happy building, Lucas Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 8, 2017 Author Share Posted January 8, 2017 Hi Lucas Slow start at the moment as we are still recovering from Christmas! I have also looked at fuel tank positioning. I intend to use a 10oz Slec tank (yellow) so F3 and F4 will need to be opened out a little so the tank will fit. Peter Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted January 8, 2017 Share Posted January 8, 2017 Nice looking lump for the business end Pete John Quote Link to comment Share on other sites More sharing options...
Lucas Hofman Posted January 9, 2017 Share Posted January 9, 2017 Hi Peter, F3 and F4 take most of the forces from the upper wing (and the landing gear too). If you have to open them up significantly it may be wise to glue some reinforcement (ply strips, hard balsa) along the edges. Lucas Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 10, 2017 Author Share Posted January 10, 2017 Hi Lucas and John My rendition will not have a top hatch as per the plan as I will not need access for a battery. I will be looking at some strengthening at the front end due to engine selection but have not got to look at yet. I will only need a very small of opening of F3 etc for the tank but will look at cabane mounts very carfully. Engines looks fab! Peter Quote Link to comment Share on other sites More sharing options...
Lucas Hofman Posted January 10, 2017 Share Posted January 10, 2017 Hi Pete, I am not happy with building in the cabane fixings, so plan to have a hatch between F3 and F4. If you do not have a hatch big enough for tank removal, how can you inspect and (if needed) replace it? In case this is a stupid question, keep in mind I only fly electric... Lucas Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 10, 2017 Author Share Posted January 10, 2017 Hi Lucas Im looking at this and think it best to use same type of fixings as for the engine mount. Rejgarding the fuel tank access will have to be through F3 so Im looking to see if some extra strenght would be a good idea on F3 and F4 Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 17, 2017 Author Share Posted January 17, 2017 Progress to date has been limited due to decorating taking priority😐. Also finally had time plus weather to fly today. Took my 2016 mass build Ballerina😊 Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 21, 2017 Author Share Posted January 21, 2017 Decorating now finished so now I have had some time to look at Skywriter. As the first photo shows F2 and F3 offered up on the plan with a SLEC 10oz tank in position and the intended power-plant. Looking at this the centre of the tank is just below the needle so I will open out the top of the F3 cut out accordingly. Probably about 1/8in or so, not much more. I may well add a wee bit of additional strength to F3 as a result of this but it looks no big deal. It is good to get the tank position just right as it pays dividends with the running of the engine. Also thinking on I would expect to extend F2 down a bit to where the tank will be. Do not see any real issue at all. Full steam ahead. Watch this space. Edited By Low pass Pete on 21/01/2017 16:18:14 Quote Link to comment Share on other sites More sharing options...
Stumps Posted January 21, 2017 Share Posted January 21, 2017 Hi Pete, I've been looking at the Skywriter with the view of using an OS52fs that I have spare. Like you, I've been trying to come up with an engine and tank layout using the same Slec tank. The problem I've found is where there cabane struts sit in the fuselage. The tank has to sit lower than is desired without altering their anchor point height. As an alternative I've thought about lowering the engine slightly. Do you have any thought on this? regards Ant Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 22, 2017 Author Share Posted January 22, 2017 Posted by Stumps on 21/01/2017 16:45:51: Hi Pete, I've been looking at the Skywriter with the view of using an OS52fs that I have spare. Like you, I've been trying to come up with an engine and tank layout using the same Slec tank. The problem I've found is where there cabane struts sit in the fuselage. The tank has to sit lower than is desired without altering their anchor point height. As an alternative I've thought about lowering the engine slightly. Do you have any thought on this? regards Ant Hi Stumps One simple way to get a bit more tank height would be to use a SLEC Red tank instead of the yellow. That would give an extra 1/4in to raise the tank. On reflection I may well use a red tank. I used one on my Ballerina build with an OS52 4 stroke and duration is just fine. As a final resort you could use a SLEC Blue tank and that would gain 3/8in height. Looking at the OS instructions for my OS62 it says "Locate the fuel tank so that the centre line of the tank is approx. 10mm below the centre line of the needle-valve". As I intend to invert the engine with a small mod to the F3 tank access hole ( make access hole taller), use a red tank, I think that the right position of the tank can be achieved. I think the same height would apply to an OS52. In the past as a rule of thumb to get the centre line of the tank in line with the centre of the needle valve works for me OK. However if more height was needed then the only option would be to redesign the cabanes or as you say lower the engine a tad. My choice would be to lower the engine as a very last resort as I would prefer to keep the thrust line as per the original design. Hope that helps. Cheers Peter Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 22, 2017 Author Share Posted January 22, 2017 Posted by Low pass Pete on 22/01/2017 04:35:35: Posted by Stumps on 21/01/2017 16:45:51: Hi Pete, I've been looking at the Skywriter with the view of using an OS52fs that I have spare. Like you, I've been trying to come up with an engine and tank layout using the same Slec tank. The problem I've found is where there cabane struts sit in the fuselage. The tank has to sit lower than is desired without altering their anchor point height. As an alternative I've thought about lowering the engine slightly. Do you have any thought on this? regards Ant Hi Stumps One simple way to get a bit more tank height would be to use a SLEC Red tank instead of the yellow. That would give an extra 1/4in to raise the tank. On reflection I may well use a red tank. I used one on my Ballerina build with an OS52 4 stroke and duration is just fine. As a final resort you could use a SLEC Blue tank and that would gain 3/8in height. Looking at the OS instructions for my OS62 it says "Locate the fuel tank so that the centre line of the tank is approx. 10mm below the centre line of the needle-valve". As I intend to invert the engine with a small mod to the F3 tank access hole ( make access hole taller), use a red tank, I think that the right position of the tank can be achieved. I think the same height would apply to an OS52. In the past as a rule of thumb to get the centre line of the tank in line with the centre of the needle valve works for me OK. However if more height was needed then the only option would be to redesign the cabanes or as you say lower the engine a tad. My choice would be to lower the engine as a very last resort as I would prefer to keep the thrust line as per the original design. Hope that helps. Cheers Peter As an addition to make last comment. If the tank is too high you will run the risk of siphon action which make mixture adjustment very difficult. Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 22, 2017 Author Share Posted January 22, 2017 Posted by Low pass Pete on 22/01/2017 04:41:40: Posted by Low pass Pete on 22/01/2017 04:35:35: Posted by Stumps on 21/01/2017 16:45:51: Hi Pete, I've been looking at the Skywriter with the view of using an OS52fs that I have spare. Like you, I've been trying to come up with an engine and tank layout using the same Slec tank. The problem I've found is where there cabane struts sit in the fuselage. The tank has to sit lower than is desired without altering their anchor point height. As an alternative I've thought about lowering the engine slightly. Do you have any thought on this? regards Ant Hi Stumps One simple way to get a bit more tank height would be to use a SLEC Red tank instead of the yellow. That would give an extra 1/4in to raise the tank. On reflection I may well use a red tank. I used one on my Ballerina build with an OS52 4 stroke and duration is just fine. As a final resort you could use a SLEC Blue tank and that would gain 3/8in height. Looking at the OS instructions for my OS62 it says "Locate the fuel tank so that the centre line of the tank is approx. 10mm below the centre line of the needle-valve". As I intend to invert the engine with a small mod to the F3 tank access hole ( make access hole taller), use a red tank, I think that the right position of the tank can be achieved. I think the same height would apply to an OS52. In the past as a rule of thumb to get the centre line of the tank in line with the centre of the needle valve works for me OK. However if more height was needed then the only option would be to redesign the cabanes or as you say lower the engine a tad. My choice would be to lower the engine as a very last resort as I would prefer to keep the thrust line as per the original design. Hope that helps. Cheers Peter As an addition to make last comment. If the tank is too high you will run the risk of siphon action which make mixture adjustment very difficult. Finally if the hole in F3 is made taller then I would strengthen F3 to make sure the cabane attachment is man enough for the job in hand. Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 22, 2017 Author Share Posted January 22, 2017 Anyway completely sticking to the plan is not 100% binding. subtle changes are good as it makes one think about problems such as the engine tank position and solve them before build starts. No so in ARTFs. Edited By Low pass Pete on 22/01/2017 04:51:31 Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 22, 2017 Author Share Posted January 22, 2017 Ref tank position.. decision taken to use a SLEC red tank and to modify F3 and F2. 1. Need to have a cutout in F3 just wider than the tank approx. 1/4 in deep. 2. I decided to double up F3 to add strength. Dummy set up to show basic position of tank centreline compared to needle valve. There will be just enough headroom between top of tank and the cabane mounts. I will epoxy the cabanes to the plates and also add nut and bolt (just in case). 3. As F2 is moved rearwards then it will need to be made longer. About 1in of so. Looks as if the original line of lower plate can be the same. 4. Overall arrangement allows for centre of tank to be just above needle valve or if required it can be lowered about 1/2in if required. 5. Bonus is that no top hatch will be needed for my build. Edited By Low pass Pete on 22/01/2017 19:37:55 Quote Link to comment Share on other sites More sharing options...
Lucas Hofman Posted January 23, 2017 Share Posted January 23, 2017 Hi Pete, A significant change the other way: I move F2 forward and make it lower, you move it back and make it higher!. Would it be wise to use blind nuts for the cabane struts? Less chance on a nut loosening when you mount the cabanes and the possibility to remove them (although if you use epoxy you may not get a damaged one out without damaging the surrounding, so then it does not matter. Lucas Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 25, 2017 Author Share Posted January 25, 2017 I have commenced build a have noted a number of anomalies on the supplied plan and wood cut outs. Please see my blog on the Skywriter Design thread. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted January 25, 2017 Share Posted January 25, 2017 Read em Pete thanks. John Quote Link to comment Share on other sites More sharing options...
Low pass Pete Posted January 29, 2017 Author Share Posted January 29, 2017 Undercart modified from the spares I held. Applied a little heat using the hottest burner on the cooker then clamp in a vice and bend gently. Just need to drill ready for stub axles. The heat did not damage the paint finish, surprisingly, but will refinish anyway. Edited By Low pass Pete on 29/01/2017 15:49:38 Quote Link to comment Share on other sites More sharing options...
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