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Low pass Pete's MB2017 Skywriter build

Skywriter

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Low pass Pete27/12/2016 21:40:08
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260 forum posts
147 photos

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

Low pass Pete06/01/2017 09:24:08
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260 forum posts
147 photos

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

john stones 106/01/2017 16:05:05
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11529 forum posts
1517 photos

Sounds good Pete, picture when it arrives photo

John

Low pass Pete07/01/2017 15:42:48
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260 forum posts
147 photos

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.

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Low pass Pete07/01/2017 15:50:32
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260 forum posts
147 photos

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 rightwink)

 

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Edited By Low pass Pete on 07/01/2017 15:52:34

onetenor07/01/2017 17:16:07
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1901 forum posts

Don't forget to anneal the dural before bending Ask me how I know

Lucas Hofman08/01/2017 14:46:29
668 forum posts
375 photos

Shiny and new! Glad someone else has started too!

Happy building,

Lucas

Low pass Pete08/01/2017 19:02:13
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260 forum posts
147 photos

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

john stones 108/01/2017 19:12:36
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11529 forum posts
1517 photos

Nice looking lump for the business end Pete yes

John

Lucas Hofman09/01/2017 07:25:08
668 forum posts
375 photos

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

Low pass Pete10/01/2017 07:57:12
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260 forum posts
147 photos

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

Lucas Hofman10/01/2017 08:43:05
668 forum posts
375 photos

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

Low pass Pete10/01/2017 18:09:09
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260 forum posts
147 photos
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
Low pass Pete17/01/2017 19:07:52
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260 forum posts
147 photos
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😊
Low pass Pete21/01/2017 16:13:29
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260 forum posts
147 photos

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.

img_5993.jpg

Full steam ahead. Watch this space.

img_5994.jpg

Edited By Low pass Pete on 21/01/2017 16:18:14

Stumps21/01/2017 16:45:51
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53 forum posts

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

Low pass Pete22/01/2017 04:35:35
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260 forum posts
147 photos
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

Low pass Pete22/01/2017 04:41:40
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260 forum posts
147 photos
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.

Low pass Pete22/01/2017 04:47:31
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260 forum posts
147 photos
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.

Low pass Pete22/01/2017 04:51:01
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260 forum posts
147 photos

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.smiley

Edited By Low pass Pete on 22/01/2017 04:51:31

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