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Trevor Grace 117/09/2019 13:21:27
35 forum posts

i intend to build a 48-50 inch w/s flying wing type model using a irvine 53 and wondering if anyone could give me an idea on the size of 3 bladed pusher prop. looking at about 3lb -3 1/2lb flying weight

many thanks.

Nigel R17/09/2019 13:28:28
avatar
3394 forum posts
524 photos

you sure you're going to need a .53 in something weighing 3-1/2lb?

anyway, I thought the rule of thumb was, standard prop size, minus one inch diameter.

Trevor Grace 117/09/2019 14:01:00
35 forum posts

hi Nigel R. thanks for your reply, i went electric a few yrs ago so lost touch with the i.c. world, the engine (brand new) has been sitting in my shed all of this time. Not making

exactly a flying wing but a star wars type twin fin long nose job. Will be making it up as i go along but loosly based on the KR84 TORTUGA Robodrone.

Martin Harris17/09/2019 14:07:16
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9084 forum posts
224 photos

If "push" in the thread title refers to the engine, be very cautious with an Irvine. The needle valve is extremely close to the propeller arc - Irvine users regularly get a slap on the knuckles while making adjustments to engines fitted with conventional props. If you try this with a pusher prop it will almost certainly inflict serious injury due to the blade coming at you at a chopping angle which pulls the blade into whatever it contacts.

I was bitten (twice in one day) back in the 70s by a pusher driven by a little Veco .19 - I still have the scars to remind me. I shudder to think what an Irvine 53 would be capable of.

Edit: Just spotted your last post after posting this and it seems to confirm it's a pusher.  I would seriously advise against the Irvine unless you can arrange a remote needle adjustment.

Edited By Martin Harris on 17/09/2019 14:17:05

Don Fry17/09/2019 14:51:47
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4384 forum posts
52 photos

I too have the scars of adjusting, in my case a pre Scnurl (spelling?) ported plain bearing 40. So a tidier to the power of the Irvine. When I had a 53 Irvine it was as big as ever I flew alone. I had eternal debates with myself as to wheather I could get to casualty if it bit me. And working behind the engine was tight. I ended up with a simple expedient, slow needle, stop engine, and adjust. Main needle, Ok with caution,

On a pusher, I would not touch those needles if it's running. Have you thought of the launch, a chuck, excepting one of those underhand discus affairs also brings digits to the slicer.

Denis Watkins17/09/2019 15:02:44
4055 forum posts
75 photos

With the Irvine Trevor

You could fly a 6lb model with a 10 x 6 3 blade prop

These models are usually driven by .36 - .39 motors

Trevor Grace 117/09/2019 15:04:48
35 forum posts

hi guys the remote adjusting needle valve will be no prop, what has got me foxed at the moment is the exhaust to prop clearance.

Don Fry17/09/2019 15:14:19
avatar
4384 forum posts
52 photos

True, but I bet it's a dose of fun on a 53.

Trevor Grace 117/09/2019 16:12:35
35 forum posts

hope so as for the props, had a fight with a 20x8 a few years back-guess who won.

Nigel R17/09/2019 16:18:06
avatar
3394 forum posts
524 photos

"what has got me foxed at the moment is the exhaust to prop clearance."

Just point it forward. It'll look a bit funny but will work fine.

Or

a) find a dustbin, or a pitts type, or some other compact silencer type

b) fit a pusher pipe (weston do them)

re, Tortuga drone, try:

**LINK**

note, prop in correct (!) place

a bit smaller than you are looking for but could easily be scaled up a bit

Trevor Grace 117/09/2019 18:51:08
35 forum posts

thanks Nigel R. I will check the Weston link.

ps you have got the wrong plane the TORTUGA -KR84 is on the microbirds.com and type in TORTUGA

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