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Buzzard Bombshell

Making a s/h model work for me.

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Braddock, VC15/08/2019 17:47:00
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1626 forum posts
76 photos

A few years ago I bought a second hand buzard bombshell, mainly bought it to try out electric flight.

As soon as I got home I knew I'd made a mistake as the esc didn't work and the centre of gravity was literally miles out, so much so that I had to fit 700 gms of Pb up front.

It flew but it was still tail heavy so I lobbed it in the back of my workshop with a view to putting a nice little 2 stroke in it.

Fast forward to last week when I pulled it out to start work.

It's really too flimsy to pop an engine in so I started looking over how I could make it work for me.

There's a pic nearby showing a glued in hatch that covered up where the servos were, two massive metal geared chinese servos that weighed just over 100 gms.

I cut a new hatch in and made and fitted a ply mount with two corona HV digitals. Pulled the snakes out of their tube and substituted a 14 swg wire rod for the rudder and a 2mm round carbon rod as the elevator pushrod in the original tubes. The wire rod had adaptors soldered on and the CF rod had them glued on.

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Braddock, VC15/08/2019 17:52:19
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1626 forum posts
76 photos

To continue, I fitted the wing and with the balance point set at 42% needed just 330 gms (the new servos are mounted at the C of G site)

Because of the flimsy front end I encapsulated the lead in gorilla glue as ther's nothing really strong enough to bolt the stuff to.

That's where I'm at at the moment waiting for the GG to set.

Braddock, VC15/08/2019 18:06:35
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1626 forum posts
76 photos

Here's the glue setting, everything is wrapped in polythene sheet and the bands are holding the battery hatch on.

I'll have to make a pattern for the windscreen which was made out of thin mylar and disappeared on the first flight I had with it.img_0027 (1).jpg

Braddock, VC16/08/2019 11:30:23
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1626 forum posts
76 photos

img_0029 (1).jpgPics of the lead gorilla glued in place, tried shifting it, it's well and truly fixed.

Also access hatch for the servos, 1/8" bass gussets and held on with servo screws.

Just have to iron down the film and make the windscreen now , also some form of battery retention, stick on velcro hasn't taken to the battery.

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Braddock, VC18/08/2019 11:42:00
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1626 forum posts
76 photos

Well it flew, still seems either over elevated or the c of g is too far bck. I'll try 3mm of light ply under the wing trailing edge at first to see if that sorts it.

PatMc18/08/2019 12:20:12
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4193 forum posts
520 photos

If you reduce the wing incidence you will also be reducing the motor downthrust, why not simply adjust some down on the elevator ?

Braddock, VC18/08/2019 21:23:43
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1626 forum posts
76 photos

Good point, Pat. I think I'll try some more lead in the nose as that's the easiest option even though my head tells me the c of g isn't miles out as it has a lifting tail section and my other oldies with similar arrangements fly with a c of g in excess of 50% chord from the leading edge.

I'll let you know how I get on, but it won't be for a while as the grandson is coming down for the week and all the old men up the flying site give him the heebie-jeebies.......disgust

PatMc18/08/2019 23:06:00
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4193 forum posts
520 photos

The model you have seems to have been altered from the original to suit the builder. There are 3 versions of the BB on Outerzone, the 1940 original, a kit from the 1970's & a RCM mag's plan also from the 1970's. The original mentions the cg as being about 33% & the RCM plan shows the same position but the kit version has it at around 45%. They all have the same shorter nose length than your model seems to have & none have lifting tail section, they're all symmetrical.

Good luck with the grandson, we look after our (now) 4 1/2 year old granddaughter at least one day per week but have never yet taken her to the flying site. OTOH she's had me on a kid's slide (nearly got stuck embarrassed) & on the roundabout (dunno how I used to manage flying C/L crook) a couple of times at a local park. Always knackered by the end of the day but enjoy every minute of it. teeth 2

Braddock, VC19/08/2019 01:00:15
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1626 forum posts
76 photos

Yes, I noticed the variations with the CG, also the plane is built from a laser cut kit. the really annoying part has been the wood selection eg the top cabin rails are made from 3/8 triangle section that is soft as butter, some of the formers are soft 1/8 sheet and the beech engine bearers, which tend to stiffen up the structure, have been omitted.

It'll probably fly fine when I get it sorted but today I took off in flat calm and two mins into the flight half a gale blew through, high pucker factor.

Grandkids are a law unto themselves, mine is 7 going on 45 he's very technology biased and gets quite cross when I drag him outdoors, but he loves playing poosticks on the bridges over the streams in our village, as do I; it's all I have the energy for !

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