'Returner's questions'

[Ian McTaggart]

I'm starting again after over 50 years and I got such good advice from you all when I asked about a suitable motor for the original KK Super 60 kit I got for £10 on Gumtree that I hope you will indulge me with another dilemma: - which doesn't involve R.C. or E.

I'm getting back into the hobby by restoring a free flight Frog Tutor with a Mills .75 that has been on top of the wardrobe since I was a lad. I will try and post some photos because the resurrection has been quite amazing.

Here's my question: I didn't think it wise to run the motor with a 55 year old Keil Kraft nylon propellor, so I ordered some new ones. Oh how things have changed!

I need help in selecting the most suitable prop for free flight with a Mills .75.

Very happy if someone says none of the ones you have bought are suitable - try .............

All are "8x4":

Kavan: colour yellow, but the blades have quite a wide chord and the trailing edge is prominently curved.

Graupner: nice looking grey prop but the hole is enormous! The mills prop- shaft is tiny.

Master Airscrew G/F series: Good profile with l/e & t/e that could double up as a modelling knife but the packet says 'For Glow and Electric Power'. Sounds irrational I know, but is it ok for a small, elderly diesel?

Thanks, Ian.

[Peter Miller]

The Master Airscrew will be fine. Just sand off the moulding flash round the edges.

I have actually carved balsa with them just to photograph as a warning to others.

I once was asked to hand start an engine for someone whose starter had gone flat. He had not sanded the flash off.

Lets just say that he never, ever did that again after I had "explained" in detail what he had done wrong

[Robin Colbourne]

The crankshaft on a Mills .75 is pretty flimsy by modern standards. They were protected in the old days by the use of wooden props which broke, or flexible nylon props which flexed. I wouldl be tempted to use the Kavan prop as a bit of insurance against 'arrivals'.

Other similar props are Tornado and Top flite if you can still get them.

Failing that, I would try this 8.5x4 Bolly Prop: **LINK**

I second what Peter has to say about sharp edged props and have the scars to prove it. Holding a knife blade a t right angles to the prop leading or trailing edge and dragging it along a few times will get rid of most of the moulding line, which can then be finished off with emery paper.

[Peter Miller]

4 plus list 8X4 wood propellers intended for electric power however I know that these would be safe on a Mills .75

[Ian McTaggart]

Thanks for your great advice, chaps. Very much appreciated.

I'm going to try the Kavan prop. as it is the most flexible and not dissimilar to the original 1960's KK prop - and I just happen to a have a collet the right size for it.

By the way, after I took the old KK prop off, after about 55 years, I thought it could do with a clean. - a few rubs with a 'Sterets' alcohol wipe brought it up like new.

If the Kavan doesn't work out I shall look at wood props. The 'strong and stiff ' philosophy doesn't really seem right for balsa and tissue.

Thanks again.

Ian

[jrman]

I would boil ( about 5 minutes) the old nylon props to restore their moisture content before using them.

[Ian McTaggart]

Thanks jrman but I won't risk running the 55 year old nylon prop , although I may use it for 'posing' with the model so it looks original.

[gangster]

Ah boiling props. That brings back memories