CAD Designing my own Electric Foam models

[Dazzy]

While Im waiting for my Flitetest.com order to come in I got started on designing a Nieuport 17 model, this model is based on a pdf file that I got from somewhere but cant rememeber where. Anyway I thought I post about my design process given that many people seems to ask where, how and why etc with CAD models for RC design. Now dont take my word for it as I could be dead wrong about the design process but Ive been doing tech drawing for the last 5 years.

To check my work I even bought a book from the US ( it only took 4 .5 weeks to arrive ) titled Model Aircraft Aerodynamics by Martin Simonds and Im having a blast reading it and comparing his knowledge with my design, so far so good.

Okay so heres a simple render of the Nieuport 17 that I did this morning. Theres nothing really special to the 3D render, but it does serve as the the basis for getting the drawing correctly scaled before committing to a design.

And heres some of the process steps and renders for background information, starting with a wire diagram of the key parts. Now I only drew one half of the drawing but after reviewing my that half it was not clearly comprehendible what I was was looking at at so I added the 2nd/other half of the fuselage just for clarity.

So heres the references that I used to get to this point in time.
Nieuport 17,pdf

Heres a reference image that Ive used for the Nieuport cad design.

And finally here an image that I layed side to side the Nieuport 17.pdf inside my CAD program for further reference.

I just scaled this image above to the imported pdf file and adjusted the XY scale accordingly. The benefit here is that while the pdf and this image share many similarities that are not an exact match, but they share enough like to like detail that makes designing a much simpler approach.

So my general approach to designing rc models is:
1. If the plans have a scale use it for now, models can be re-scaled later. Insert the reference pdf into your cad program.
2. Draw the profile of the fuselage/wings using splines, curves, lines or polylines ( or whatever tool youve got )
3. An alternative is to draw the formers as a starting point.
4. Using lofting tools and or simple extrudes to create the overall structure
5, Check your design against a suitable image thats not necessarily part of the reference pdf. maybe a wikipedia source image, then compare.
6. Happy camper then move ahead, otherwise refine your drawing techniques ( splines, curves, lines or polylines etc )
7. Got a suitable cad drawing thats comparable to the image ( Nieuport_17_C.1_French_First_World_War_single_seat_fighter_colourized_drawing.jpg ), then great move ahead.
8. Now hide all your lofts, solids, surfaces and extrudes etc that form part of the rendered view and just leave the basics like splines, curves, lines or polylines etc.
9. Example: Say in the case of an open spline ( closed splines dont work here ) that is used as the basis of part of the fuselage, what you need is to get the total length of that spline/polyline and to lay it flat on your workspace, this way your creating a 2D flat drawing. This 2D drawing is then used as the basis of cutting the foam.
10. Youve gotta lay out these 2D reference lines as per 9 above in the same manner that you created them in a 3D space. By that I mean by using the same spacing apart from one spline/polyline to the next spline/polyline etc, maintaining the correct spacing until youve laid out all the 2D profiles for the fuselage/wing ect.

More to come...

 

[Dazzy]

Just waiting on my flitetes order to come in, waiting and waiting so I thought Id share what Ive ordered and ask a few question to boot.

Heres the order:

So in my 1st post Im talking about the cad design of the Nieuport 17, Id like to know if any one can give me the dimensions of the power pack c battery, also dimensions on the ar620 as these dimensions will form the basis of scaling the the Nieuport down to a size that compatible with these products?

Why are there 2 props in the radial edition C power pack?

Is the gyro really necessary, I bought it on the off chance that Id make heaps of mistakes/crashes early on?

Okay so Im a newbie with aspirations of creating my own rc aiplane design a little further down the track so in the mean time Im cad designing just for fun?

 

[Dazzy]

So heres the Nieuport 17 pdf file overlaid with the wire diagram of the splines, polylines and elliptical curves from the fuselage. The red outlines of the fuselage are the lofts used to create the basic shape.

And heres a similar image with an outside image scaled to the same size just for reference while drawing the Nieuport design.

 

[Ketchup]

Well, so I can’t answer your questions about the battery/rx size, but I can answer the other one. So there are 2 props in the c pack because the props in the package come in packs of 2. So basically hq sells them in packs of 2, so ft just takes one of those and puts it in the c pack box.

 

[JasonK]

also having extra props is nice as your likely to break a few (I haven't been flying for long and have broken 4-6 props).

I do see an issue between the Aura 5 light board and the receiver you have there. I have that same receiver and as best as I can tell it doesn't have serial/PPM output which is what the Aura 5 Light board uses an an input.

 

[Merv]

Great looking design

 

[quorneng]

Dazzy
I appreciate you have already bought your gyro board but by far the simplest solution is to buy a Spektrum compatible gyro rx like this one from Lemon.
Nothing fancy it just adds gyro stability, so no panic button or anything like that, but the degree of gyro is adjustable and it is can be switched on/off from the Tx so you can learn how your plane really flies.

Like all WW1 biplane types, particularly with a scale wing section, it will be pretty sensitive to the CofG position. Remember also the full size wings were thin and relied entirely on the rigging for strength and rigidity. Models are stronger for their size but it is quite likely you will need some support from the rigging.

 

[Dazzy]

Dazzy
I appreciate you have already bought your gyro board but by far the simplest solution is to buy a Spektrum compatible gyro rx like this one from Lemon.
Nothing fancy it just adds gyro stability, so no panic button or anything like that, but the degree of gyro is adjustable and it is can be switched on/off from the Tx so you can learn how your plane really flies.

Like all WW1 biplane types, particularly with a scale wing section, it will be pretty sensitive to the CofG position. Remember also the full size wings were thin and relied entirely on the rigging for strength and rigidity. Models are stronger for their size but it is quite likely you will need some support from the rigging.

Thanks @quorneng thanks for the feedback, yeah I was intending to add some rigging but not sure whats suitable, any ideas?

As for the wings when you look at my 1st posts image the wings do seem to have little thickness around the middle of the wing profile so I took the later option and added a more suitable profile that I saved from wikipedia. Point is the wing profile from the original picture looked a tad too difficult to create out of 1 or 2 sheets of foam, alternatively the wing rib would be mighty slim. I will post about the two variations that Ive seen for a better understanding of the good and bad regarding alternatives. Thanks for your comments.

 

[quorneng]

Dazzy
Contrary to much opinion I have found nylon mono filament line quite adequate. It is very strong and yes it does stretch a bit under load but particularly for foam wings this is not really an issue as foam tend to 'give' anyway.
My AN2 has foam wings with no spar. The wings are probably just about rigid enough by themselves to fly but they are also rigged with 10 lb mono filament line. It is worth noting that just a single strand will carry over 5 times the total weight of the plane so the degree of stretch of the rigging is always less than the likely 'give' in the foam.

The wings are just thin Depron top and bottom skins over ribs so rely just on the strength of the foam and the rigging.

It can be easily picked up 'ready to fly' by just the tips of the upper wing which gives the equivalent aerodynamic bending load on the wings to pulling at least a 4 g manoeuvre. As a result It has been looped with no ill effects.
Much of the secret to a successful plane is knowing how and where weight can be saved.
After all the power to fly is directly proportional to weight so less weight means more 'spare' power.

 

[Boberticus]

Dazzy
Contrary to much opinion I have found nylon mono filament line quite adequate. It is very strong and yes it does stretch a bit under load but particularly for foam wings this is not really an issue as foam tend to 'give' anyway.
My AN2 has foam wings with no spar. The wings are probably just about rigid enough by themselves to fly but they are also rigged with 10 lb mono filament line. It is worth noting that just a single strand will carry over 5 times the total weight of the plane so the degree of stretch of the rigging is always less than the likely 'give' in the foam.
View attachment 172174
The wings are just thin Depron top and bottom skins over ribs so rely just on the strength of the foam and the rigging.
View attachment 172175
It can be easily picked up 'ready to fly' by just the tips of the upper wing which gives the equivalent aerodynamic bending load on the wings to pulling at least a 4 g manoeuvre. As a result It has been looped with no ill effects.
Much of the secret to a successful plane is knowing how and where weight can be saved.
After all the power to fly is directly proportional to weight so less weight means more 'spare' power.

how did you attach your rigging to the spar\brace? is it just looped around? could you take a closeup?

got a Airco DH2 in the works and rigging is the last thing i need to plan out

 

[SP0NZ]

The battery range for the Corsair is 2200-2800. The 1800 mAh pack you bought might work, but I think the Corsair definitely likes the bigger packs. John Overstreet (the designer of the Flite Test Master Series Corsair) uses a 4S 3000 mAh as his go to in these warbirds. Make sure you get the CG right.

 

[quorneng]

Dizzy
Sorry to be hijacking your thread.
Boberticus
As there is no spar as such the rigging is attached to small thin acetate sheet anchors long enough to be glued right through the wing onto both the top and bottom wing skins.

A short cut in the Depron allowed the pre-glued anchor to be inserted into the wing just ahead and behind the inter plane strut.

The inboard was done in a similar way except for the lower front which uses the undercarriage strut retaining pin.

Which is exactly where the full size does it.

 

[Dazzy]

Dazzy
Contrary to much opinion I have found nylon mono filament line quite adequate. It is very strong and yes it does stretch a bit under load but particularly for foam wings this is not really an issue as foam tend to 'give' anyway.
My AN2 has foam wings with no spar. The wings are probably just about rigid enough by themselves to fly but they are also rigged with 10 lb mono filament line. It is worth noting that just a single strand will carry over 5 times the total weight of the plane so the degree of stretch of the rigging is always less than the likely 'give' in the foam.
View attachment 172174
The wings are just thin Depron top and bottom skins over ribs so rely just on the strength of the foam and the rigging.
View attachment 172175
It can be easily picked up 'ready to fly' by just the tips of the upper wing which gives the equivalent aerodynamic bending load on the wings to pulling at least a 4 g manoeuvre. As a result It has been looped with no ill effects.
Much of the secret to a successful plane is knowing how and where weight can be saved.
After all the power to fly is directly proportional to weight so less weight means more 'spare' power.

Thanks mate, yeah Im sure mono filament will do the trick.