Douglas X3 Stiletto

Do you know any Olympic Javelin chuckers? 

I used to represent my school at the javelin a while ago about 70 years, i would most likely put my fingers through it now as i seen to get clumsier with each passing year 

It's the same for me, Tony
 

My heaviest jet, the Hunter F6, uses the same 50mm EDF and has a wing loading of 8.24 oz/sqft, however its wing is swept 45 degrees whereas the Stiletto's is not.
Doubling the wing loading means the launch speed will rise by 40%. Maybe a touch less given the Stiletto's full span flaps will be set to 10 degrees.
My biggest concern is not the increased launch speed but the reduced thrust resulting from the bifurcated exhaust.
The quicker it accelerates to a sustainable flying speed the less likely it will "meet the ground" before it has.
Its going to be a interesting too find out. 

The new basic 6ch Lemon Rx arrived today to replace the Lemon stab Rx in the Hunter F6 so it can be used in the Stiletto!The 4s battery and Lemon stab in place.
 
The wires will be tidied up but of more concern is the HK Tx6i uses channel 5 for the dual aileron and its associated flaperon feature. The Lemon however uses channel 5 to switch the stab feature on and off.
At the moment I have dual ailerons using a "mix" to set the LH aileron on channel 6 and can switch the gyro on/off in flight but no flaperons.
At the moment I can't think of a way of moving the ailerons in unison say 10% ands 20% down using a 3 way switch other than by setting the gyro permanently on so it releasing channel 5 for use by a servo..    . 

Time to invest in eight-channel gear? 

I am sure more modern kit would be able to do what I want but I am only using 4 channels on the X-3!
It is just that the Lemon Stab receiver and the HK TX6i have different ideas on which channels should do what!

Ready to go less paint it weighs 440g  (just under 16 oz) so it does not "feel" impossibly heavy for the wing area particularly as on 4s it seems to have quite sufficient thrust.
I am sure a fixed 10 degree flap will provide the necessary "safety margin" of lift at the launch.

Now I have an actual CofG position there are just the three finger holes to add to the underside and it will be ready to try!

  

The Stiletto os now very white having been given a light coat of acrylic.
 
It always surprises me that no matter how much care you think you have taken the first paint coat reveals all sort of dents and blemishes.
After some thought the easiest way to make the finger hole "tubes" is to print them in LW-PLA.
 
All three holes are under the wing so each tube has a firm base to be glued to.
Two sized a slightly larger one for my thumb. This means the X-3 is a left hand launcher!  

The three LW-PLA finger holes added.
 
Although the aileron servo are fully built in unusually for me the servo arms and the retaining screw is readily accessible.
 
 It seems rather than make some special longer servo  links to achieve a 10 degree permanent flap it would be easier to simply move the servo horn round one spline with advantages it would be just as easy to reset the flaps if and when I find a way to use a proper "flaperon" system. 

Nothing to do with the Stiletto but this is what happens if you print an object with a 5% gyroid fill but in error set the outside wall flow to zero.
 
A free standing fill. 
  

Pretty - but not much use! 

U started thinking about how to make the long and fine nose of the X-3.
I wondered if it would be possible to print it in LW-PLA. Further more there would be advantages in "Lofting" it as well.
It would have to be in many section to keep with the limitations of the printer.
Progress so far.
 
It will be over 800mm long!
At least by printing it would be relatively easy to make another as it is likely get damaged in anything but a perfect landing.
  

To see how strong/rigid a LW-PLA nose might be I printed "test" one.
 
8 sections but the smallest first two are printed in one piece. The remaining six have 3mm Depron formers to provide support at the joints.
 
Tedious to do but it is commendably light at 12g.
No matter what nose I end up up I fear it will end up as a single flight "disposable" item even with magnet retention.  
 

BMFA elfin safety might object if they see you flying a giant lawn-dart! 

Those stubby wings look like they came off a F104 

Yes - the tailplane!