Anybody else scratch building tonight?

Leaded50
The distance between the inlet and exhaust is fixed so it all comes down to which suffers the most from the lack of space. The inlet area is above the FSA whereas the exhaust divides & tapers down to 90%. My experience suggested it was more important to maintain a good exhaust path than the inlet given the inlet velocity will be only about 80% of the exhaust.
Surely 350g thrust down from 500g is a reduction of 30% not 50!
I am building the plane to take into account the limited thrust. It should still fly adequately on a 70% thrust to weight ratio particularly given its generous area & un swept wing. It won't be a 'rocket ship' but then neither was the full size. ;)
We shall see.
Well said. Well thought out.
 

quorneng

Master member
Slowly making progress. The fuselage centre section skinned.
The LH inlet.
LhInlet.JPG

The LH exhaust.
LhExhaust.JPG

Part of the wing root underside is left open so the aileron and elevator servo wires can be fed through the formers to the cockpit area.
There will be quite a bit of sanding, filling and general tidying up to do.
 
Last edited:

leaded50

Legendary member
Leaded50
The distance between the inlet and exhaust is fixed so it all comes down to which suffers the most from the lack of space. The inlet area is above the FSA whereas the exhaust divides & tapers down to 90%. My experience suggested it was more important to maintain a good exhaust path than the inlet given the inlet velocity will be only about 80% of the exhaust.
Surely 350g thrust down from 500g is a reduction of 30% not 50!
I am building the plane to take into account the limited thrust. It should still fly adequately on a 70% thrust to weight ratio particularly given its generous area & un swept wing. It won't be a 'rocket ship' but then neither was the full size. ;)
We shall see.


I see you have thought it over, and hopefully you get it to work :)
Im not quite agree ;) on your thoughts on the inlet velocity vs exhaust though.... without any good inlet, the EDF exhaust will lack much..
In my experinecs with different EDF´s even with more than enough FSA, it easy lack power if it need go in high angled inlets.. you can have a hole in fuselageside to the EDF fully open, but as long air need travel 90 degrees to the EDF inlet, it will lack effect a lot. Im scrapping a "jet" seaplane for that reason... it cant be built with straight enough intake.. only way to fly it, is without the canopy and pilot, so air can fully go into that place direct to the EDF. Not superb for waterspray :)
 

quorneng

Master member
The Sea Hawk wings are structurally very simple. Two 5 mm XPS sheets cut to size and simply drawn over two tapered XPS shear webs to give a near symmetrical section.
LhWing2.JPG

By far the most tedious and messy part is sanding down the inside of each sheet to give a fine trailing edge.
The aileron servo is let in through the lower skin and lies flush with the lower skin surface.
AilServo.JPG

The aileron is top tape hinged so is very free moving. Just as well its only a 3.7 g servo! Atleast with no ribs it is easy to feed the extended servo wire through the wing.
Next is the frightening bit. The wing is simply glued directly onto the centre section. No reinforcement. Its all just XPS foam.
LhUpper.JPG

The foam safe glue I am using eventually dries rock hard so a good 'skin to skin' butt joint is virtually as strong as the skin itself. A bit of filling and sanding to hide the joint. The end result is of course remarkably light and hopefully adequately strong.
 

Battery800

Elite member
Idea for a new project hopefully for combat at ff 2022: so I get a big plane of some sort (probably a giant-ish guinea) that carries a huge net for combat, which opens up and brings down any planes in its path. Second idea is a guinea with a wide wing that has about... 20 wing servoes that
Launch a mass strike of some sort
 

Matagami Designs

Master member
Figured it was about time I shared what I have been designing the past few weeks or so. :geek:

1626750998936.png


The idea is that it will be a twin 50 mm EDF but I feel I wanna try as a pusher 1st to see how flight worthy it is. Still a good bit of initial design to do but I think most of the idea is there. Challenges at this point are the canards/elevator servos n such and wing construction.
Design is inspired from @Namactual 's dat rhino.

1626751346567.png
 

quorneng

Master member
The rear fuselage for the XPS Sea Hawk built in the same way as the fuselage centre section.
RearFuse1.JPG

The more complex shape and the small radii make the planking a challenge in 5 mm XPS.
The completed rear fuselage glued onto the centre section.
RearFuse4.JPG

Still the tail surfaces and the fuselage nose section to do.;)