H/K F18 Hornet has landed

[Tim Mackey]

Details. The maiden flight used a 2.6Ahr 3s nanotech battery, which gave an AUW of a rather portly 1lb 14oz, and previous power testing with a 3s showed 370 Watts static, so around 200 watts per pound. This flew the bird fine, I landed after 4.5 minutes, and the charger pumped back in just 1300m/a. Glad to report that the added wing spars, and modified elevator coupling worked a treat

As stated launch speed needs to be higher than can be easily achieved by a simple hand launch.

I hate bungees, so plan to move up to a 4s pack, which showed a rather whopping 740watts static in earlier testing ( see above )

I do have 2 x 4s packs which may fit the bill - but to keep the weight down, capacity will have to be less than the 3s nano pack.

The problem is the 2300 4s that I have is only 20C ( max 46A ) and the earlier testing showed peak current at 51+ Amps.

I have a nanotech 25 -50C pack which is good for 45 -90 A, but its only 1800mahr.

This could mean very short flight times

Gonna have to think about this one, and maybe do some more testing of the 4s setup.

The model suffered a crack almost right through the fuselage near the front end, probably from one of the aerlier aborted launches - easily fixed, and then I shall beef it up with C/F rod and probably glass the whole underside - scuffing around the intakes is evident already from just today's testing. FOD is also easily ingested into the fan unit, so a mesh guard will need to be made up and fitted over the intakes and cheater holes.

 Pleased to report that the cheap H/King "orange" park fly receiver behaved impeccably.

A few pictures from back home, still awaiting JBs proper shots

 

Possible 4s contenders

scuff marks and the remarkable £10 orange receiver - aerial just visible

 The battery used today fitted in the bay created to achieve the correct COG

The broken fuselage

 

Overall, well impressed for the money. If I had a tarmac runway site, Im sure ROG would be far easier than hand launch, but I dont - and besides...... dangly legs on a jet just look stupid.

[David perry 1]

Nice report Tim, very glad it all went well.

 

Also pleased re the Oranges!! I have four and all work fine. 

 

David 

Edited By David perry 1 on 14/10/2010 20:25:59

[Tim Mackey]

Cheers david.

Not quite sure what has happened to the pictures, but JB has just sent a couple of low resolution jobs...more later I hope.

 

 

Edited By Tim Mackey - Administrator on 15/10/2010 08:06:30

[Tim Mackey]

Right heres the pics of some of the mods

1) cheater holes

2) battery bay

3) spars added and film strip covers

4) elevator coupling

Thanks for the pics JB

[David Ashby - Moderator]

Nice one Tim and nice shots JB

[Tim Mackey]

Cheers

JB just sent a couple of replacement shots over, so I have put these up instead.

The light was very poor, and the model fast and small - a pretty tough combo.

Im sure we will have some much better ones in future.

 

I am pleased enough with this cheapo foamy to now spend some time on sorting out the issues, which will include getting the right 4s fitted, light glassing of the underside, CF reinforcement in a few weak places, tidy up the battery bay, and enlarging the cheater holes even further and then fitting some FOD grilles.

 

Anyone got any ideas what I could use for grilles? .....needs to be

 

A) Very lightweight

B) Small enough mesh to work - but large enough to not restrict airflow

 

[Ultymate]

Tim I've used some mesh from a stick on sunshade to keep sun off babies in the back of the car to cover the carb intake on one of my petrol engines to stop any foreign matter getting ingested from inside the fus in the past. I found the one I used on a visit to the tip one day and I've just been up in my loft to see if I had any remnants left sadly I haven't.

[Tim Mackey]

Cheers Brian, I will have a look at that idea.

[David perry 1]

Netl for keeping Herons of ponds.   It might be called strawberry netting too come to think of it.  Its  black so "invisible".  You'll get it from garden centres!

 

Ive had a look and all I can find here is green stuff with a mesh of about 1cm square.  You could double it or tripple it of course.  Otherwise I'd go for the black stuff from  garden centre.  If you want mine let me know. 

 

 

D 

Edited By David perry 1 on 15/10/2010 11:06:01

[Ed Darter]

those nets that you get a bunch of Babybel minis in ? holes may be a bit too large for what you are after.

[Tim Mackey]

Some good ideas there - I think it may need to be a little stiffer than merely netting though

[Colin Naylar]

cut up either-

plastic flour sieve from the poundshop?

or-

or a plastic colander (strainer) from the poundshop?

[TonyS]

Its a bit of a faff but you could use a sheet of plastic film (the stiff stuff used for OHP's etc) and a paper hole punch....then spray it the colour you want. That way you get the right no of holes to suit....

[TonyS]

Or... plastic film covered in Solarfilm (dark blue might work) then punched...?

[Tim Mackey]

I like the colander /sieve idea.

I did think about acetate or similar and hole punching...but I worried that there may be too much restriction...this fan is very thirsty for air.

[David perry 1]

Plastic tea strainer?

[Tim Mackey]

Ok thanks for the ideas guys, as it happens I was wandering around the local Aldi and spotted this. Scraped off the non stick covering and it took glue fine, easily cut with scissors, so job done. Seems to be a Fiberglass mesh under the coating.

 

To finish this "build" thread off, heres the last few shots.

The three previous landings ( two were arrivals from a failed hand launch ) caused a crack across the fuselage, and also some scuffing and light damage to the intakes.

So I patched up the scuffs, and cut a thin line into the fus sides and epoxied in some carbon fibre flat strip.

 

the lot was then spackled over, primed, painted and finally covered with light glasscloth and epoxy laminating resin.

 

 Due to lack of power, hand-launching was a bit iffy ( I am thinking of a dolly system buts thats another thread )  to overcome the problem I am going with a 4s 2150 battery on the lander 4300 kv fan, so have modified again the area I made for the battery to get the COG right.

Closed up a lot of the area previously opened - used expanding builders foam and spackle. Heres the old 3s battery space

 

And the new 4s space - glassed and painted. Note the battery retaining strap.

 The new FOD grilles were glued in place, and more strips of F/G and resin applied to finish off, and also offer some scuff protection to the soft foam on the landing areas.

Look a bit tatty in close up and flashlight, but at a distance, they are fine. Its all pretty much underside anyway, so wont be seen much. I will be leaving the battery bay open, to aid cooling, and again, not really visible in flight.

Test report on the 4s flight as soon as the weather behaves.

 

Edited By Tim Mackey - Administrator on 27/10/2010 14:31:25

[Plane Addict]

Is that a plane from the mini series?

 

Anyway, nice work... hope that weather becomes good soon, we are moving to the worse part of the year too.

[Tim Mackey]

No not the mini series...its the Art Tech one.

[Plane Addict]

Ic, now I read the thread again it was obvious it is not a jpower plane

[David perry 1]

Tim,

 

Whats the final weight evolution? All your bits of glass here and carbon there, what have they added over the "stock" weight?

 

D 

[Tim Mackey]

"Stock" target weight is 640 gram all up.

Airframe sans battery is  655 grams ( 23 oz )

Absolute final AUW  (4s) is bang on 907 grams ( 2lbs ) so almost 50% heavier, a lot of which is down to the lander all meta fan unit, and of course a much larger and heavier battery than suggested for stock model ( 1300ma 3s )

Testing with new 30C battery arrived this morning gave the following figures ( static ).

51A, 14.2v, and 728 Watts.

Obviously the power will drop off in flight a bit, but I still reckon on around 350 Watts per pound.   Should go well

 

I have just taken delivery of a second unit for a mate...and he is going to build it absolutely stock....so will be interesting to compare.

[Pete B]

Presumably you'll be landing this on some salt flats, Timbo - Bonneville or Mojave Desert, perhaps?..........

 

Pete

[Tim Mackey]

LOL- hopefully not quite that long a walk Pete

[Tim Mackey]

OK I promise no more boring pictures of the job after these last few

These are the batteries I intend using.

I cut off the fitted plugs and extended the cables slightly and added my connectors of choice ( 4mm gold ). A sellotape tab was attached to aid in removal from battery bay.

The battery is slid in from the front, and the cables exit into the cavity behind the cockpit - accesible through the previously formed removable section - where they are connected up to the ESC, trough the top access hatch hole.

Heres the bay, and its associated wooden strap tab,and the battery in situ.

A shallow foam "shelf" wedges the battery in place once its slid right in.

 

This shows the battery in place, ready for strapping in - the blue colour of the pack was an unexpected bonus - its barely visible

The bay will be left completely open, and a section of clear canopy was removed which will draw air out over the pack.

Final job looks pretty reasonable