The 'Mode-zero Goblin' a simple S/C or intermediate glider

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iflylilplanes
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Re: Recreating the Irvine Pixie S/C or intermediate glider

Post by iflylilplanes »

I will take the adjustable approach, and build a pod I can tilt with a couple of locking screws, and adjust my way to the correct angle. Thanks for the start and stop angles, from the sound of it on some aircraft it's not critical.
Cheers,

Dave
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Sundancer
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Re: Recreating the Irvine Pixie S/C or intermediate glider

Post by Sundancer »

The pods I have used on such models as the Soarcerer and Amigo have always been set at zero relative to the datum from which the wing incidence is measured, as is the one on my current Frog Tarquin, which although it has an elevator spends 90% of the time flying as a rudder/throttle model. Never felt the need to change the thrustline, but these models are/were all very gently powered. I suppose if a lot of power is used, forcing the model to fly much faster than it's normal glide speed and hence generate excess lift then maybe some downthrust may be required??
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Igull
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Re: Recreating the Irvine Pixie S/C or intermediate glider

Post by Igull »

Sundancer wrote: 25 Jul 2018, 06:45 as is the one on my current Frog Tarquin
Frog Tarquin??
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Phil_G
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Re: Recreating the Irvine Pixie S/C or intermediate glider

Post by Phil_G »

If you think about the geometry of a pod, where all the thrust is on the end of a long lever, I wouldnt expect a few degrees either way to have any effect at all :D


@Neil, bearing in mind what we've been discussing here, are you happy for this thread to stay or should we hide it?
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Igull
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Re: Recreating the Irvine Pixie S/C or intermediate glider

Post by Igull »

Phil_G wrote: 25 Jul 2018, 18:33 If you think about the geometry of a pod, where all the thrust is on the end of a long lever, I wouldnt expect a few degrees either way to have any effect at all :D
When I said that there may be some 'aeronautical arguments', I think I might have been right :mrgreen:
It's not just as simple as it might appear at first and there are far more inputs to the problem than simply putting the thrustline at 0/0. It may well work for some very low power applications and it may well work perfectly ok for the 'ixie'. That 'thrust at the end of a long lever' is what it's all about - that and how far it is away from the Cp and the CG - but I'm not going any further than that as complete boredom will set in - just suck it and see :lol:
@Neil, bearing in mind what we've been discussing here, are you happy for this thread to stay or should we hide it?
Perhaps renamed might be a better solution. It's probably too late anyway as the BOT's will have been and recorded everything anyway :-)
Are we any further forward on a naming solution for this 'ixie' do you think - I'd like to draw a line under the plan :?
Martin
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Re: Recreating the Irvine Pixie S/C or intermediate glider

Post by Martin »

Sometimes thrust lines on power pods work because of how the prop wash blows on the tailplane. The effects vary from model to model depending on the tailplane position and area. If you only have enough power to give a fairly gentle climb then you don't need to worry about it and zero upthrust or down thrust is fine.
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Re: A new, as yet unnamed S/C or intermediate glider

Post by Martin »

We were flying today on Bosley Minn (South Easterly slope of the Leek and Moorland club - LMMGA) and I snapped this photo of two mythical creatures alongside a bird's thumb (click and click again for (much) larger view).
Pixie_Elf_Alula.jpg
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Igull
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Re: A new, as yet unnamed S/C or intermediate glider

Post by Igull »

Has some dastardly company copied the Mode Zero Goblin already ????? I think we should collectively sue them :lol:

The Dreamflight Alula and their Weasel/Trek are IMHO probably the best performing aircraft ever made on the planet - I spent two happy hours up a warm hill yesterday morning with the Weasel Trek - such a great model.

Ron and his eclectic mix of Sharkfaces might disagree though :lol: :lol: :lol:

Cheers

Neil
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Mike_K
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Re: A new, as yet unnamed S/C or intermediate glider

Post by Mike_K »

Martin

Is part of the Elf wing missing, or is it an optical illusion? The reason I ask is a I have a spare set of Elf wings somewhere in the shed if it would help you.

You have two of my favourite models in the photo, I fly my Alula (Evo) and Elf more than all my other models put together. You can fly them nearly everywhere can't you! If I'm feeling lazy, I launch my Alula from the garden, while walking to the paddock, well it saves carrying it... And it has flown from numerous parks, slopes, road-side verges, sand dunes. Brilliant fun.

Cheers

Mike

PS have you built the Goblin already?
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Sundancer
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Re: Recreating the Irvine Pixie S/C or intermediate glider

Post by Sundancer »

Igull wrote: 25 Jul 2018, 15:48
Sundancer wrote: 25 Jul 2018, 06:45 as is the one on my current Frog Tarquin
Frog Tarquin??
Yep, one of Frog's lesser known designs and an absolute delight. This is mine which has a 50 watt outrunner propped for less than 40 watts. 36 inches span and a lovely performer at 200 grams. As I said it really doesn't need the (one sided) elevator (although it is useful when flying in a bit of wind, which it does remarkably well for such a small light model), flys just fine on rudder/throttle. Interestingly it was designed by Frog from the outset as a power model (for the Frog 50), F/F of course, rather than glider with added power pod. For anyone wanting a pretty and "different" single channel model with a great glide and thermal/slope soaring potential you could do a lot worse. I love FROG designs!
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