Whizza!

[Jim (Chairman)]

All,

In mid-November I intend on getting a Woodpack for an electric Whizza!

I don't yet have any plans or build manual, so I was just wondering how many / what type of servos were needed?

I'm guessing 3 x Standard Size Servos: Aileron, Rubber & Elevator...?

If someone could let me know so I can get them ready...

Cheers!

Jim

[Chairman]

I put three of these in Jim (I think).  Metal geared just to save on stripping gears when I bash the model on a doorway. There is also a digital version.

http://airtekhobbies.com/genas90mg.html

While a woodpack is a slightly quicker way to build, there's absolutely nothing on a Whizzza thats at all difficult to cut out.
See my build blog here http://www.modelflying.co.uk/forums/postings.asp?th=75236

PS - Every now and again, ask me what models I'm selling, over the next 12 months or so... 

[Jim (Chairman)]

Chris,

All understood...

Er, what aircraft are you selling over the winter?

Saying that I derive much of the pleasure of the hobby from the build phase. Plenty of opportunities to put my own touches and features on the build.

Any chance you could copy me the list of raw wood that's needed to build a Whizza, and I'll price up what it would cost from Mikes "Happy" Models....?

I think Morgan is going to lend me his plans to photocopy...

Cheers!

[Chairman]

Hi Jim

I assume you're OK with a wood list now you have the plan?

Planes I'm selling - TBH not decided yet. Possibly:-

Staufenbiel Do27 1.6m Zebra,

1400mm Foamy FMS Hellcat,


(Whizzza sized) P51 Miss America,


Little Cermark Dragonfly glider


Who knows, I'll probably change my mind a few times.

[Jim (Chairman)]

All,

My Whizza build is moving along at pace.

Fuz and tail feathers are built but not actually joined yet.

The whole lot now needs covering with Solarfilm etc.

On that point, I have a question for you all.

What's the best / recommended thing to "seal" the balsa with before it gets covered with film?

I just figure that the dry porous balsa surface will not take film well untreated and I don't what balsa grain showing through.

Thanks!

[Chairman]

Hi Jim

Bare balsa is in fact the best thing to stick any of the iron on films to.
If you seal the surface you tend to trap lots of air bubbles, and the only way to get those out is to prick each one with a pin. Porous balsa lets the air through.

If an edge isn't sticking down well, and to seal against that icky fuel ingress, people use balsaloc (a heat activated brush on glue) underneath Or Solarfilm Clearcoat, which is more varnish like, takes film on top of it, and also dries to a shine that matches the solarfilm surface it's self, so is OK to seal edges with afterwards.

With electric models though, I just iron the film on the balsa and that's it. Just arrange it so edges are trailing in the wind, rather than facing it.

[Jim (Chairman)]

Chris,

Thanks for that, I probably would have gone and plastered varnish / sealant / something all over it tonight and that would be that! Glad I asked the question...

Balsaloc is available from Mikes Models, but if I don't need any sealant then that can wait until the covering stage.

Hobbyking do an interesting film that looking like brushed aluminium. I'm going to try that with some "carbon fibre" decals...

I'll try to get some photos tonight and upload...

Cheers!

[Chairman]

Brushed aluminium and carbon sounds smart Jim.

It may be worth some sort of range test just in case it does actually contain aluminium, 'cos there's a very small chance it will affect the RF.

Another covering technique worth a mention is for going round compound curves. Here, shrinking the film is often not enough for a neat job. Instead, if you cut the pieces generously so there's something to hold, and once one side is attached, pull as you heat, to stretch it around the piece. This way it will pull around the curve (mostly).

[Jim (Chairman)]

Chris,

Thanks for the tips!

The "brushed aluminium" film is here: https://www.hobbyking.com/hobbyking/store/__62898__Covering_Film_Bright_Silver_5mtr_406_UK_Warehouse_.html

I don't think it will contain aluminium but I'll range-check it anyway...

Do you recommend a sealing iron or heat gun for doing film?

I used a sealing iron on the Fledging rebuild and it was annoying but ultimately OK.

The Whizza is mainly striaght lines so I won't have too many issues with compound curves.

Back to shaping....

[Chairman]

I managed for years with a travel iron Jim. "In hotel" covering was done with the cheapest possible iron from Argos. (under a fiver)
If you use the domestic one, just make sure you clean any colour off it before it's used on clothes again!

Having said all that, the prolux iron with the LCD display is useful, in that you can set, and read off, the exact temperature.

Careful with a heat gun, even for shrinking. Some films can be overheated. Two things can happen here: 1) You can put a great big hole in it quite easily. 2) It can look fine, but having been overheated, it will wrinkle badly in the sun.

Have a look at the solarfilm instructions on their website. They are a good indication of technique.

[Jim (Chairman)]

Some photos from my Whizza build...

Overall shot with the Carbon Fibre spar tube clearly visible before balsa capping:



Nose section still unfinished, waiting for spinner before shaping:



Main components:



Battery and sevo hatches:



Rudder and elevator bits:



What it really needed is a "rubber duck" style antenna, and yes, the actual RX antenna (one of them) will go in there!



Possible canopy layout, if I can get the aileron servo to fit:



Not very exciting I know, but I'm quite happy with it seeing it's my first (very simple) balsa scratch build...

Jim

[Chairman]

It's looking great Jim.

Doesn't matter how simple or complex it is, it's always exciting seeing a new model come together. 

[Jim (Chairman)]

Chris,

Just been flying, nice calm morning.

John and Morgan were there with their Whizzas...

I've gone for a front mounting motor arrangement as you can see in this photo:



John thinks that this might not be a good idea due to motor cooling issues. Valid point!

I also want a 51mm diameter spinner (on the plans) for visual reasons.

In your experience, could motor cooling be an issue here? Or is it a "suck it and see"...

I will be doing much motor / prop / power testing on the bench, so hopefully any issues should show up then...

Cheers!

[Chairman]

I've been clearing out a garage while swearing at the good weather, all day today

It's probably worth opening up the ply mount to match the cooling holes at the front of the motor. But then, the spinner will deflect the cooling air anyway as you suggest.

It probably depends just how hard you're pushing the motor. John and Andy do seem to like to "get their moneys worth" out of electric motors and batteries 
If you're not pushing so hard, you may well be fine, especially with that scoop under the nose. Just make sure some air can get out further back too.

I always try to fly a maiden for just a minute or two, and then land to check temperature of motor, batt and ESC.
Keep an eye on it, it should be fine.

[Jim (Chairman)]

To help with motor temperature issues(?) I've broached out the motor mounting plate, and given the Whizza some exhausts!

Hopefully the exhausts will venturi some air past the motor...