Project M120 Black Hawk

[Benvk]

Another rainy windy day in London, it's driving me nuts...3 weeks now and counting..

So, Project M120 Black Hawk has started.

It's a 1/48th scale kit that I bought for a fiver from ebay. I'd already spent a few hours with a CAD program working which kits at which scales would likely fit the size of the M120 and D02s, there's not that many to be honest! A 1/48 Sea King kit might also be good but they are very expensive and hard to find.

So here are pictures of day 1 of the build. Had to get the dremel out and cut some of the body off but not as much as expected. The tail boom as been rotated 180 so the tail rotor is on the opposite side as per a previous discussion on another thread.

I'd love to be able to mount the tail rotor up on the outrigger tail for accuracy but can't find any parts in micro size to do that yet. Any help with that would be appreciated.

You might notice that the main shaft and rotor head sits too high to be accurate so I'm planning to cut the main shaft down, loose the crap anti rotation device and make my own based the D02S. I think I can loose at least 15mm off the shaft by doing this.

Also planning to shorten the tail blades so that the whole heli sits lower to the ground as it should.

Once I'm happy with the fuselage, the airbrush will be dusted off to paint this thing. Haven't used it for a couple of years so looking forward to that.

Cheers
Ben

[Magooch]

That's pretty slick

[Heli-opolis]

You never cease to amaze me with the stuff you think up!!

[Benvk]

Now I know why the kit was so cheap, it's missing the windscreen.

Anyone got any good tips on how to scratch build one?

[john aeras]

You could carve a form out of foam put some heat resistant silicone over it and cut a flat piece of clam-shell packaging to put over the foam form.
Take a heat gun to it slowly and it should form. Trim off as needed.
I personally haven't tried this, but seen a friend use the technique.

[Benvk]

Thnk you, I'll give it a go..

[Benvk]

Well, I'm an idiot.

I should have checked to see if it would fly before I went to the effort of painting it!!

It's just too heavy at 45g and even with full throttle, it barely makes it into a hover.

Oh well. you live and learn.

[Magooch]

It looks good though
check these out, been wanting to order one but have to many projects at the moment...
http://darthdrk.4t.com/photo3_6.html

[Benvk]

I just don't like any of the off the shelf scale fuselages that I've seen for micro helis. There's zero detail in the moulds so they don't look much better than strapping a plastic coke bottle to your heli.

I know that it is possible to convert plastic kits, this guy has made lots.
http://agusta.ms.u-tokyo.ac.jp/agust...o-plastic.html

I guess it's just a power to weight ratio thing and sub 200 size helis are not really suitable.

[Benvk]

Tried some weight lifting today, on the M120, not me personally!

The results were quite interesting.

I stuck some packing tape between the landing skids and placed a D02S battery on it. It lifted off into a hover with very little effort. Then I placed another battery on and again it lifted off and although I could tell it was struggling a bit, it hovered nicely.

I was quite surprised at this because 2 x D02S batteries weigh about 30g. So I got the mini drill out and attacked the hawk fuselage, cutting some of the underneath off where it doesn't show and shaved as much excess off from inside as I could and got the weight down to 35g.

Put it back on the M120 and moved the battery forwards to get the COG right but it still wouldn't lift off correctly. It just wanted to tip over backwards or sideways or any which way and I bent the feathering shaft again when the rotors hit the ground. This shaft is crap and way too weak, will probably have to swop to the D02S head.

I'm wondering whether the weight distribution is causing a problem for the gyro. It's happy enough with all the extra weight below the main shaft but not with it dispersed from nose to tail.

Got the 15500kv motor coming tomorrow so I'll see if that makes a difference plus I'm going to make a carbon main shaft as well.

[Benvk]

Pissed off today big time..

Straightened the feather shaft, installed the new motor, ran it up on the bench and all seemed fine but a test flight was impossible as the heli is now totaly uncontrollable. Spins around as if the tail gears are stripped and wants to flip over as well.

After all the hours I've put into this, I'm now back to square one with trying to get it to fly straight again even without the hawk fuselage..

This hobby can be a total bitch sometimes...

[Heli-opolis]

"Heli's a bitch, and then you crash."

What's worse though, the fact that it is uncontrollable or the fact that you did it to yourself?

One hopes that the risk vs. benefit of thinking outside the box is in one's favor but sometimes, all you get is the box.

[bvento]

Originally Posted by Heli-opolis

One hopes that the risk vs. benefit of thinking outside the box is in one's favor but sometimes, all you get is the box.

I always liked boxes growing up as a kid!

[Heli-opolis]

When I was young, I used to have more fun with the boxes some toys came in than the toys themselves.

Sometimes one can do more with one's imagination than the physical reality.

And then there is Benvk who seems to meld both together pretty well!

Usually.

Seriously though, it's too bad it is too heavy to fly because it is one sweet looking bird!!

[bvento]

Originally Posted by Heli-opolis

Seriously though, it's too bad it is too heavy to fly because it is one sweet looking bird!!

I agree! Is pretty bad ass... I'm sure you'll find a way to make it work Ben!

[Benvk]

Well, got the M120 flying again and with the new motor.

Took me ages to find the fault, it was the cable from the rudder servo. The plastic covering had worn away from rubbing against the metal clip that holds the cable to the frame. Must have been shorting out the servo because it was pirouetting at random.

Haven't tried it yet with modified fuselage.