An EDF 'Jetex' Vampire

In response to Andy's challenge to build a KK or Veron FF kit I intend to build a kit designed by Jetex (originally for a Jetex 100) but to convert it to RC and EDF!

Very conventional balsa construction and at 25" span a bit bigger than the KK equivalent Venom which was only 17".
Searching through my 'spares' I have a working 40mm EDF with a broken fan, a spare fan, a tiny Orange 2.4 radio (4 channel) and a 20A ESC.
So far so good. A few calculations.
At 25" span the 40mm EDF will go inside the fuselage easily enough.
At 32mm the jet pipe shown on the plan is exactly 85% of the EDF's FSA. This is the exhaust area that is judged to give the best EDF performance.
With a bit of care the inlets shown on the plan can give exactly 100% of the FSA.
The EDF, fan, ESC, radio and 3x2.5g servos on the scales shows 1.2oz
Airframe say 1.2oz
Battery (950mAh 2s) 1.5oz
Total 4oz.
And the 40mm EDF is claimed to give 4.9oz thrust at 18A!

On paper at least it looks good to go !

Sounds good Q.......... and as you're the first to post, I'll match it with a KK Venom for Rapier Rocket.

Andy Sephton wrote: Sounds good Q.......... and as you're the first to post, I'll match it with a KK Venom for Rapier Rocket.

Change of plan!

WHile hunting out my old copies of Veron plans in the search for something to build with a prop on the front I found the plan to the Jetex powered Veron Sea Hawk. It was too good to miss and I'd completely forgotten I had the plan tucked away. So, my jet build will be the Sea Hawk for Rapier Rocket.

Wow, better than 1-1 power Still remember ours it's with its one and only flight (Jetex) about 1952. Disapeared in in the distance over The Explosive Works. Look forward to this Build thread.

Now the bench is clear(ish) I can start seriously thinking about the 40mm EDF Vampire.
The fuselage obviously has to have a big internal duct and working air intakes but its basic shape (and thus the formers) and stringers will be unchanged.
The big difference is removing the non scale FF dihedral which actually has an impact on the geometry of the wing root air intakes as well.
A start on the revised plan.

The quite a bit of thinking still to do.

This is turning into a bit of lark!
First, that down loaded Jetex drawing is very suspect. The left and right sides of almost everything in each view are different sizes and by quite a bit too. For example the LH wing in the front view was 1/8" shorter then the right!
I have resorted to select/copy/flip/paste to make sure all L and R sides are identical in every view.

Second, the redesign of the fuselage is/will be rather extensive so little of the original design will be left.

I have also changed the tailplane to a symmetrical section rather than the flat bottom one shown in the plan. I will probably change the wing section as well to a 'thin' Clark Y.
This is what the plan look like so far.

That inlet duct is going to be a nightmare to make.

but if anyone can do it, it will be you.

I think in terms of drawing this is about as far as I will go.

I have laid out the fuselage formers to show the EDF and exhaust duct (which are simply circular) but the internal inlet shape is so complex I shall have to more or less build the fuselage and then cut things away appropriately and just hope I can skin the inside from the outside!

The Vampire fuselage will be of 'composite' construction. The stringers will be balsa but the formers and nose block will be Depron. I expect the wing will be similar.
A very modest start. Former F6 glued to the EDF.

Rear of this the formers will be held in place by the paper thrust tube.
Forward of the EDF I haven't worked out how to do yet!

The mandrel for the thrust tube.

With the paper thrust tube in place formers 7 & 8 go on then the wing root ribs. These in turn support formers 5 & 6.

So far its all 3 mm Depron.
The inlet duct in 2mm Depron is next.

This is where this build get a bit ridiculous - that inlet duct!

About the only thing that can be said for it is being all Depron it is very light but fitting the pieces by trial and error is very slow and the resulting shape probably has questionable aerodynamic form.
The thrust tube is fine so I can only hope the 'shortness' of the inlet ducting makes up for any 'shape' inefficiency.

The next issue is just how small the fuselage is. It is going to be quite a struggle to get just the ESC and battery in.
At least I can put the radio in the wing by the RH tail boom where it can pick up the elevator servo lead.

With a bit of 'jiggling' the ESC and battery box go in.
The battery box provides the support for the remaining fuselage formers.

It will use the same battery as the Canberra 950mAh 2s.
The EDF has been tested 'insitu' and it delivered just a fraction over 3oz thrust drawing 10.1A (82W).

Nearly ready to start adding the balsa stringers!

It's looking good Q, you have a remarkable skill with Depron!

When you next take a photo, would you put a ruler in the frame, please, so we can have an idea of the size you're working to.

Thanks,
Andy