50 inch Sipa S-200

[Stephen Jones]

Hi ,

I have been toying with the idea for some time about making a much bigger version of the Sipa S-200 .

Problems i could envisage are, too large to fit in my loft/man cave so wings would have to be removable and a propeller would strike the ground before take off .

I have redesigned the model and come to the conclusion that i could get away with a 6 inch propeller (so long as i fit under carriage) and make the outer part of the wings removable .

Leaving the booms , tail plane , rudders and Centre section of the wing all as one i could then get it into my loft space , the outer section of the wings would measure 17 inches each in length .

I have built the lower section of the body to give me an idea of scale .

At its widest point it measures over 220mm so hand launching it is out of the question .

I have bought several 700 watt edf motors to try out 284507.

With a 6x3 prop on a 4s 2200mah 25c battery i am pulling over 800 watts.

With a 4.75x4.75 prop i am pulling 546 watts , so this will give me much better ground clearance but a third of the prop will be obscured by the rear of the model .

Also if i redesign the body shape to one of the slimmer version of the sipa and remove part of the jet nozzle to bring it back in line with the wings the opening will be 70mm in diameter so it might be possible to go down the EDF route .

So my question is

If i go with the prop version what size battery would i need to get a 6 minutes flight and would the loss of prop area mater or due the the loss of prop area simply go for a 5x4 prop ?

Steve.

[Stephen Jones]

Ok,

I have done some more searching on this plane and while i think my version is very close in appearance to the full size, i am not so sure of the back end.

As none of the pictures i have seen show clearly what it looks like.

How ever some more pictures have appeared on the Webb.

So look at these,

The top picture does not show the outline of the body but in the next Cutting you can see a plane which indicates the outline of the under body shape by way of a dotted line and a solid line indicating a smaller top Part.

Steve

[Stephen Jones]

And theres more,

This one can not see due to the light.

If you look closer it looks flat at the back on this next one,

Steve

[Stephen Jones]

Oh look at the latest banner on Minijets.org

 

This has only just been added, i have been trying to get on there Webb site but was under construction.

And their is the Modded Sipa S 200 with the T-58 engine and wing tanks,

 

Steve 

Edited By Stephen Jones on 14/01/2017 23:30:04

[Stephen Jones]

Incidentally do a Google image search for this picture of my plane and see how many webb sites are using it .

Steve

[Stephen Jones]

Gosh,

It`s about time i made a start on this one .

So i have started the Re Drawing of this one.

No better drawings out their for this plane so i will try to do my best interpretation of this one and the one i made.

I am going to see if i can make the wing a shoulder fit with a section that fits over the top of the wing to complete the body but will in part be removable to gain access to the motor much like the original.

Steve

[Stephen Jones]

Done a bit more work on the drawing.

All the formers for the body are now done.

The wing is also drawn up.

It is bigger than my A3 printer can do so i will have to tile it.

And i will make a start on building the body soon.

Steve.

[Andy Meade]

Looks nice Steve, I do like a twin boom design.

[Colin Leighfield]

It should be a nice flyer in the larger size, they’ve all worked well enough so far, haven’t they?

[Stephen Jones]

Thank`s Guys,

I have two other scale models i would like to start on, but this one has been crying out to be made bigger and better if that is possible.

I can at least try and improve the scale look of the model although i doubt it will be as fast as my 36" version.

I have yet to try and slope this one as the weather has not been favorable that is on my to do list.

Anyway i have printed out the lower part of the body and it is Big 23" long when you consider i built a small one with the wingspan not much bigger.

Not sure if the plan is visible but should give you an idea of the scale of it.

I will start to build with Depron as is cheap and if i am not happy with it i can scrap it . And restart with any modification needed.

Steve

[Stephen Jones]

Hi,

After further looking at the full size Sipa s-200 i did not like my lower curves as i continued from the front profile of the drawing. Each drawing i look at is different their is no consistency at all. Which makes things more frustrating .

So back to the drawing board and reduced the radius on the edge of most of the formers.

So the ones you see above i did not use.

I made a start today as the weather was a little warmer for me to work in my loft / Workshop.

So building is much like my first one. I start with the lower part of the body.

I cut all the formers out of 6mm Depron. And made the keel and side supports out of 1/8th balsa.

With some additional parts so that i can lower the cockpit line later.

I like using Cad as it allows me to print out all my parts on my home printer and all the parts fit nice.

Steve.

[Stephen Jones]

Continuing on,

Lower frame work now complete.

I did make a start a lot earlier on in the year by just scaling up my 36 inch design.

But i did not like the look of it, and went for the slimmer version and not the one that was made fatter to allow for two army personnel to fit in.

Hopefully this will look right when finished.

Steve.

[Stephen Jones]

Hi,

I have now added 3mm Depron Sides and Bottom to the lower part of the Body.

I have the edges to fill in Planking, or maybe see if i can cut a piece in to fit.

Steve

[Andy Meade]

Some lovely neat work there Steve, great job

[Stephen Jones]

Cheers Andy,

The strange looking missing part on the side edge is where the curves are so the Bottom and Side panels are flat and just follow the cure of the bottom part of the body.

The tricky part is to get those curved edges right.

Which i am glad to say i have managed to do it a lot easier than i thought i might.

I cut i length of aero Depron a little wider than i needed and cold bent it so that it would follow the cure.

Then while holding the middle part in place i cut a small section to fit in place, then glued in place.

Now it was just a case of holding the foam over the hole and reaching inside the body to mark cut just where needed .

Then slowly continue each section until all done.

Steve

[Stephen Jones]

I am a lot happier with the look of this bottom part of the body as it looks right from all angles.

It does not look as neat in this picture, but it is really neat.

This is a view from the inside.

This is a mock-up of the motor plate.

This is the motor i had put to one side a long time ago .

A 700w Edf motor only 28mm in diameter fits perfectly.

The exhaust port is now scale size (Tiny).

If this does not work i could always find a nice big hill to chuck it of.

I guess i had better print of the top part of the body now.

Steve

[Stephen Jones]

Hi,

Been too cold too work in my loft and my job have had me working till late so also been to tied to do some work on this model,

So, Just thought i would share my design changes on the wing mounting.

If you have a look at the full size Plane you will notice that the Pilots seat between the leading edges of the wings and that the rear of the wings has a removable section to gain access to the tiny jet engine.

And so i have decided to build the wing with the front and rear section also removed.

 

Here you can see the wing will seat between formers F5 and F8 on top of some rails. The wing will have part of the it removed to fit.

Then a top section will slide in between and on top the wing to seal it in place.

 

I have not finished drawing the parts completely yet. as one of the top rails ends up outside of the top section.

I have only decided to go down this root as a few builder of my smaller model commented that they felt that they would not be confident of getting both wing level and straight.

Although i have never had a problem. I hope that this solution will appeal to more builders.

Steve

Edited By Stephen Jones on 18/02/2018 11:30:53

[Stephen Jones]

Hi,

With all this cold weather i have not done any building work on this.

But i have been searching the net for more pictures and info.

As there has always been parts of this plane that have evade my view, the top rear and rear bottom and duct.

I have now found some more pictures that have revealed better views which has confirmed my suspicions that would need altering.

I have also found a detailed 3 view by Jean Molveau which shows panels and hatch that when compared with the better pictures that i have found rings true.

And that the wing shape is also wrong . I know the design was changed several times but all the other drawings seem more like artist impressions than showing true outline .

So i am contemplating scraping this one and starting the drawing again . Or at least change 3 of the lower formers and see what i can do with the top part.

Steve

[Stephen Jones]

Hi,

After spending much time looking over the difference between all the 3 way view drawings i have and super imposing them over the top of pictures of the full size plane. i have come to the conclusion that none of the 3 way view drawing match up with any of the full size pictures that i have, they all have some differences.

So i have decided to stick with what a have and make some subtle changes as i go along to best represent that of the full size plane.

The problem is that pictures of the full size plane have been taken in bad light or light is reflecting of the plane causing glare also the wing and boom obscure the view of the top rear of the plane and the large flap hinges stop you seeing the rear bottom of the plane.

Like so.

Which leaves us to guess what it looks like behind the wing.

I believe it looks like this,

 

A small change maybe but i am trying to make something that closely represents that of the full size Sipa or at least one of the seven versions that where made.

 

Of coarse i could change my build again once built.

Steve.

 

Edited By Stephen Jones on 04/03/2018 23:55:51

[Max Z]

Hi there Steve,

I have been following your exploits with the Sipa, I love that little plane. In fact it is somewhere in my archive of "planes to be modeled sometime", but at the rate I am designing and building I probably will never get to it in this life. Shame.

Regarding the shape of the fuselage; you have most likely done much more research than me, but judging by the pictures I have found there is no evidence of a dip in the fuselage-back like you have shown, they all show a smooth transition to the rear exhaust. I would say that the the exhaust/motor mount ia a tad lower than you have designed it, and the inner portion of the wing is faired into it, either by bending down the TE or maybe even changing the root airfoil (at the boom) to a non-symmetrical one. I do realise that bringing the motor down increases the risk of prop strike at a rog takeoff.

Max.

[Andy Meade]

Steve - are the 3-views you are using as a comparator of known providence? I've seen some fairly wild differences in 3 views of other aircraft, so much so that a line somewhere in the middle of them will do the job, and no one can tell you any different due to the lack of evidence to the contrary!

In other words don't lose sleep over it, unless you're working to factory drawings, imho

Edited By Andy Meade on 05/03/2018 10:17:30

[Max Z]

I would have thought this picture gives some clues on how the back end of the fuse looks.

[Stephen Jones]

Thanks for showing that picture which does show a very good view from the rear, However that is of the 1st one and they had many alteration since, the biggest being the booms. Being far to thin.

There is a good view of that one in a museum.

Which i have already posted.

If i built a radio controlled model of that i fear the booms would snap.

I am aiming for version 3-7.

I will try and cobble some pictures together to show you what i mean,

Steve

[Stephen Jones]

Posted by Andy Meade on 05/03/2018 10:17:05:

Steve - are the 3-views you are using as a comparator of known providence? I've seen some fairly wild differences in 3 views of other aircraft, so much so that a line somewhere in the middle of them will do the job, and no one can tell you any different due to the lack of evidence to the contrary!

In other words don't lose sleep over it, unless you're working to factory drawings, imho

Edited By Andy Meade on 05/03/2018 10:17:30

i am with you Andy,

But i think it is far to say Jean Molveau is a well respected artist and has done many drawings of many aircraft.

I guess it is a bit like not fitting a bubble canopy to a Spitfire.

And i will probable have to play about with the end look of my Sipa.

Steve

[Stephen Jones]

Here is a picture showing the outline of the body below the wing with a dotted line and a solid line above the wing.

Steve