Graupner Bell 47

[Martin_H]

I have been handed a box of bits containing a classic Graupner Bell 47 from the '70's. Not exactly in pristine condition, it shows the ravages of time from 42 years of storage in a shed in tropical North Queensland.

I remember well the adverts in Aeromodeller, drooling over the pages of exotica as a pimply faced teenager. Frustrated with lack of access to these kits (and the requisite funding) I made up in my professional career by becoming a helicopter maintenance engineer and later aircrew technical writer for the Australian Defence Force.

This will be a long term restoration project. The HB25 (specially produced by Hirtenberger for this kit) does not appear to have survived very well.

It would be a shame, I think to replace this little gem with an electric motor, so, if anyone out there can offer advice on restoration...

The other factor is the frame, and whether the years have been kind to the plastic structure. I am concerned a degree of brittleness through age may prevent the airframe surviving my unique flying (= landing) style.

So, phellow heliophiles, is restoration to flying condition a reasonable proposition or should I turn this once classic kit into a museum piece?

[Former Member]

[This posting has been removed]

[J D 8]

Some are now putting electric motors in old IC engine case's,this keeps the original look of the model but makes operating them simpler. Also less vibration would be kinder to the air frame.

[John Tee]

Mine bit the dust a long time ago but still have the 25 motor. Held together with Stablit glue and plastic wedges.

John

[Mark Stevens 1]

A nice little find. I think you'll find the plastic on that one a lot better than you realise (much better than the stuff used today hence there still a few of these machines still around and even some spares).

As for the engine, take it out and soak in a tub of household white vinegar for a day or so. It's the stuff that's meant for normal cleaning so is not particularly harsh for the job you want to do. Once done, turn it over and flush through with some light machine oil. You will now be fine for when you first fuel it up and run it.

I did exactly the same on a 40 yr old HB25 engine which was totally gummed up from old castor oil. it now runs perfectly. The white vinegar also takes good care of rust and seized nuts / bolts. I've been able to turn rusted seized nuts quite easily by hand after soaking.

The 40 yr old engine was part of a 40 yr old airframe undergoing restoration - the whole lot is now 42 yrs old and flying fine

Mark

[Mark Stevens 1]

Ignore, duplicate post - oops

Mark.

Edited By Mark Stevens 1 on 30/03/2018 08:48:33