Help! DIY Strix goblin

[hman123467]

Since shipping is far too expensive for me to get my hands on a Strix goblin, I am gonna try to build one myself, out of foamboard.
I am Using 3 sheets, one for each wing and one for the fuselage. The only difference is that the body will be a lot more boxy, as opposed to the rounded sides of the OG goblin (nose will still be curved though)
I have a few questions already though:

1. Can anyone tell me the dimensions of the fuselage for the goblin? more specifically, the width of it at the front and back, and the height and length of the tail fin? I have no way of getting the measurements.

2. Will laminating it with solarfilm be an option? Does it stick to foamboard? wanting to laminate it for extra speed and rigidity.

3. I am wanting to put in place a full-span aluminium square spar. How would I go about this? As I want the wing to be formed around the square.

4. My power setup is...very beefy to say the least. 2700-3500mah 4s, 6x4 prop, 5200 KV inrunner (yes, fifty-two-hundred RPM/V), and a 120A ESC. Not worried about the electronics, just if the foamboard (wings specifically) will survive the speed? (estimating well over 150mph (around 250-350km/h). I know it sounds a little OP for such a plane with a 1m wingspan, but I'm wanting to see how far I can physically push the foamboard without a catastrophic faliure

Any help is appreciated!
cheers,

 

[rockyboy]

1. I'd go for the eyeball approach - or take a picture from the website and figure out the proportions and work from the wingspan

2. Yes, I'm pretty sure solarfilm is low temp enough that it will work on dollar tree foam board. The hobby king iron on film certainly works - I have a buddy that's done multiple projects with that.

3. Take a look at how the Arrow wing folds around the cardboard spar, and use that for inspiration - it should work out pretty good!

4. That's the top end of what foamboard can do for sure! I'd consider using a generous amount of foaming gorilla glue in the wings joints so it foams out into the wing cavity and gives you a stronger joint. Also, at speeds like that control surface flutter will mean nearly instant catastropic failure - consider covering the elevons with fiberglass or balsa, using full length hinges to prevent any air flow between the trailing edge and the control surface, and looking into the other construction techniques NerdNic uses on his high speed designs. It can be done!

Good luck!

 

[LitterBug]

You could pick up one of the wall art posters.... https://www.readymaderc.com/products/details/strix-goblin-wall-art-poster

Cheers!
LitterBug

 

[hman123467]

1. I'd go for the eyeball approach - or take a picture from the website and figure out the proportions and work from the wingspan

2. Yes, I'm pretty sure solarfilm is low temp enough that it will work on dollar tree foam board. The hobby king iron on film certainly works - I have a buddy that's done multiple projects with that.

3. Take a look at how the Arrow wing folds around the cardboard spar, and use that for inspiration - it should work out pretty good!

4. That's the top end of what foamboard can do for sure! I'd consider using a generous amount of foaming gorilla glue in the wings joints so it foams out into the wing cavity and gives you a stronger joint. Also, at speeds like that control surface flutter will mean nearly instant catastropic failure - consider covering the elevons with fiberglass or balsa, using full length hinges to prevent any air flow between the trailing edge and the control surface, and looking into the other construction techniques NerdNic uses on his high speed designs. It can be done!

Good luck!

Thanks, I ended up using tape to cover it, solarfilm does not stick to aus foamboard very well! also the wing is one complete unit, with a 10mm aluminium tube as a spar. writing an article on it for 150mph under $100Usd. Also I have formed a piece of plexiglass for the FPV canopy, so there is even less drag!