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Thrust

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Trevor Grace 127/09/2019 09:03:26
28 forum posts

Hi All, Can anyone tell me what sort of thrust i will get from a 9x8 prop on a Irvine 53 Mk 2.

Nigel R27/09/2019 09:24:35
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3120 forum posts
479 photos

What's the application?

9x8 is an unusual choice especially on a 53.

paul d27/09/2019 09:33:25
70 forum posts
5 photos

That's a coarse pitch! one way to find the thrust is to attach a securely fixed spring balance to the model and give it the beans!

Jon - Laser Engines27/09/2019 09:37:02
4855 forum posts
180 photos
Posted by paul d on 27/09/2019 09:33:25:

That's a coarse pitch! one way to find the thrust is to attach a securely fixed spring balance to the model and give it the beans!

This is the only way to get an accurate measure of static thrust but as the prop is stalled on the ground it will not always give an accurate representation of how the combination will perform in flight

Trevor Grace 127/09/2019 09:38:23
28 forum posts

mad winter project self design/build canard pusher

static thrust is what i'm after as a starting point.

Nigel R27/09/2019 10:45:23
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3120 forum posts
479 photos

It'll rev on that prop, maybe 15k?

Speed model I assume?

Static thrust in region of 5lb, bit of a guess, but most any sensible prop on a 50 size 2 stroke will be in that ball park, so to speak.

Denis Watkins27/09/2019 11:51:24
3914 forum posts
61 photos

Is the 8 inch prop for ground clearance Trevor?

Piers Bowlan27/09/2019 11:56:24
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1896 forum posts
50 photos

Why such a small dia. prop on a 53? Is if for ground clearance on a pusher configuration? You could always go for a three bladed prop if that was the case although not as efficient as a two blade prop. Noisy too.

Beat me to it Denis!

Edited By Piers Bowlan on 27/09/2019 11:57:33

Trevor Grace 127/09/2019 13:10:12
28 forum posts

Yes ground clearance is my main concern. it will be a jetish type rear wing 2 fin/ rudders NO UNDERCART so may have to fit some type of rear skids for prop protection. max prop size would be 10ins.

Denis Watkins27/09/2019 15:27:19
3914 forum posts
61 photos

The Irvine will still fly a 5lb - 6lb comfortably Trevor

But now you propose to put it in high gear, with a 9 x 8 prop,

The model will launch very quickly

IF it had an undercarriage, the model would be able to move along the ground rapidly at high throttle

A big model from a hand launch with a rear prop? I just don't know

Though I am in favour of innovation

I have just sold one of these, this year, an ARTF kit from 2007

It had a .46 OS AX on board with an 11 x 6 prop, at 6lb, with an undercarriage

r-c-plane-long-ez-.jpg

 

Edited By Denis Watkins on 27/09/2019 15:42:49

cymaz27/09/2019 20:12:57
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8772 forum posts
1190 photos

Have a play with this

Trevor Grace 127/09/2019 20:32:17
28 forum posts

Hi Denis,The undercarriage is not going to happen, I fly off of a very remote hills/mountain covered in gorse and long grass etc so hand launch is a must. belly landings are the norm with all leading edges spars strongly reinforced with carbon rods. thanks very much for your input & remarks.

will try to work out how to get pics on this thing as the DRAGON evolves.

Piers Bowlan27/09/2019 20:58:07
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1896 forum posts
50 photos

Hand launching a pusher with a screaming Irvine 53 on a 9x8 prop. Yikes, this man has no fear! cool. What can possibly go wrong?

Nigel R27/09/2019 23:25:00
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3120 forum posts
479 photos

You are a brave man.

SIMON CRAGG28/09/2019 02:38:23
483 forum posts
15 photos
Posted by Trevor Grace 1 on 27/09/2019 09:38:23:

mad winter project self design/build canard pusher

static thrust is what i'm after as a starting point.

You could also try a three blade prop, I have been using these recently and great if ground clearance is an issue.

Also. please be VERY CAREFUL when hand launching!.

It is very easy to get caught by the prop, so probably no bare arms.

Good luck.

cymaz28/09/2019 06:16:59
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8772 forum posts
1190 photos

 

 

Rather than hand launch and risking severe injury, have you thought of a dolly? There are several web sites, designs and ideas out there

 

 

 

Edited By cymaz on 28/09/2019 06:20:26

Trevor Grace 128/09/2019 07:05:45
28 forum posts

a dolly off a mountain !!!!!!!!!!!! DO'NT PANIC....working on it.

Cuban828/09/2019 09:51:25
2774 forum posts
13 photos
Posted by Piers Bowlan on 27/09/2019 20:58:07:

Hand launching a pusher with a screaming Irvine 53 on a 9x8 prop. Yikes, this man has no fear! cool. What can possibly go wrong?

Loss of fingers? Severed arteries? Loss of the flying site because of the racket?crying

Martin Harris28/09/2019 10:26:47
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8893 forum posts
221 photos

...and it happening on a remote mountain side!

Pushers introduce a definite additional risk factor both from (if IC) tuning accidents and (shudder) hand launching. Be very aware.

Don Fry28/09/2019 10:30:37
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4065 forum posts
47 photos

If it's a Dragon, he is Welsh, and therefore fears nothing. Ask the Romans.

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