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Author Topic: "Ellipsis" P30  (Read 1434 times)
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applehoney
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« on: March 25, 2018, 07:42:36 PM »

A P30 version of my 'Ellipsis' line of rubber models just came off the board;  just requires a dusting of fluorescent red sprayed on wingtips and outer surfaces of fins.

'As is',  with tracker and batteries, it weighs in at 41 grammes.
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"Ellipsis" P30
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faif2d
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« Reply #1 on: March 25, 2018, 07:55:14 PM »

Very nicely done!  Is the plan going to end up in the Gallery?
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I used to like painting with dope but now I can't remember why!    Steve Fauble
applehoney
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« Reply #2 on: March 25, 2018, 09:59:19 PM »

Afraid I do not have a 'proper' plan, Steve -  just basic working lines on paper.

Anyway I'd have to fly and be happy with it before doing such.
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strat-o
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« Reply #3 on: March 25, 2018, 10:03:19 PM »

Neat design.  Fuselage reminds me of a Teacher's Pet by John O'Donnell--my favorite P-30.

Marlin
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gossie
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« Reply #4 on: March 25, 2018, 10:49:47 PM »

Lovely build Jim, as to be expected from you. Smiley
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applehoney
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« Reply #5 on: March 25, 2018, 11:05:05 PM »

Very different to the Teacher's Pet, Marlin   .... but the TP can still hold its own despite how old the design is.
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OZPAF
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« Reply #6 on: March 26, 2018, 02:30:22 AM »

Very nice Jim. It will no doubt need that tracker.

happy flying
John
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skyrocket
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« Reply #7 on: April 22, 2018, 01:06:37 PM »

So glad to see something new off your board!!!...can't wait to see it fly at the HOBO...going to go trimming tomorrow so I don't make a fool of myself when I see you soon...I have a bunch of stuff to trim...that Ellipsis P30 looks way cool and clean as usual from you...I got my P30 back from Florida and it is in pristine condition so I've got 2 back-ups now...RELEASE THE HOUNDS!!!!...
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Bargle
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« Reply #8 on: April 22, 2018, 08:10:41 PM »

Nice to see another Ellipsis in the stable. Hope she flies great.  Smiley
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Windbeam
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« Reply #9 on: January 17, 2019, 01:47:05 PM »

Hi Applehoney, I really like the look of that P-30. I'm kinda new to free flight and its design principles, so I'm trying to understand the unique and aesthetically pleasing features such as you built into the Ellipsis. What benefits do elliptical wings offer? Also, does a "diamond" fuselage have advantages over the more common arrangement where the sides are squared to the wing and stab? It certainly does look like it just wants to fly
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applehoney
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« Reply #10 on: January 17, 2019, 03:13:36 PM »

Thanks for the kind words, Windbeam.

I believe it's said that a full size elliptical wing, such as that of the Spitfire, has some aerodynamic advantages but requires substantial washout to overcome tip stalling tendencies and lacks  glide performance .  Whether all these theories are valid really does not concern me, as far as  model airplanes are concerned, though I concede that glide efficiency appears to be tied to high aspect ratio planforms. 

Many years ago I built a simple small model of about 20" span with such a wing just to try something 'different' - it flew very well for its diminutive size and, on the conviction that 'bigger models fly better',  inspired me to progressively build a line of airplanes of increasing size using folding propellors, varying airfoils , etc. to prove that point.

Benefit?  A low A/R elliptical wing packs square inches into a shorter span than a 'standard' structure of similar area and the shape is structurally strong and warp resistant.  Spars are shorter and lighter, trailing edge dimensions are much reduced. 

'Diamond' fuselages offer a deeper dimension than the same box set 'square' and offer a little better visibility at a distance.  Wing mounting does take a little more effort compared to strapping it down on the flat top of a box, however. ... but I think the diamond looks cool, too!   

Flying ... I build wings 'flat' .. no warps at all;  no tip stall problems ever encountered.   Stability - very good.  Glide - excellent and holds its own against 'conventional' models.

More than you ever wanted to know, I  feel.  Bear in mind that flying comments spring from larger Mulvihills ..   only one P30 in the past  (pictured) which seemed a little sluggish before I lost it into a forest and I wondered if that was due to f/w prop, power and airfoil combination not working as well as hoped; hence the 'diamond' Ellipsis with different airfoil and built right down to minimum weight.  Had no chance to fly it in 2018 .. hopefully... this year !
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skyrocket
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« Reply #11 on: January 17, 2019, 03:48:32 PM »

When Jim builds something, it would be wise to sit up and take notice...and his design understanding is spot on...in the past 5 years I've learned so much from him it is ridiculous...what was I thinking?...my own ideas go in a different direction in that I tend to use higher aspect ratios combined with under-chamber, usual something from Benedeck's stable of airfoils...sure I'm losing square inches but I like the idea of gaining as much altitude as possible to catch the thermals and try to stay out of the ground clutter...both ideas work...dealers choice...and P-30 is a great event with performance in a simple format...
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randoloid
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« Reply #12 on: January 17, 2019, 11:21:29 PM »

Beautiful build as usual Applehoney!  Whenever I feel like I'm really getting pretty good at this building thing, all I have to do is log on here and see the mastery that others possess and I'm instantly humbled again.  Never deterred, just humbled.

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skyrocket
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« Reply #13 on: January 18, 2019, 06:51:32 AM »

sweet looking color scheme...just finished building a tailless P-30 based on G. Woolls' classic "Pipstrelle"...came out at 37 grams minus the D/T fixings which I'm still trying to work out. I'm leaning towards wing tipping but I don't know which is better : LE or TE? I'm thinking LE popping up because I'm afraid  air pressure
would keep the wing down popping the TE...any thoughts?
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Windbeam
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« Reply #14 on: January 20, 2019, 07:29:44 AM »

Thanks for the explanation, I appreciate the detail. Also thanks Skyrocket, that was actually exactly where my mind was heading, wondering about airfoil use with a elliptical/ high AR wing. Just checked out your thread about the tail less model you just built, very interesting model. How big were the original plans that you scaled down to make yours? I'm building a simple p-30 called the Juiblex which I found as a plan on the outer zone website. It's got a constant chord, v dihedral, flat bottom airfoil wing and the rest of the model is similarly straightforward.
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skyrocket
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« Reply #15 on: January 20, 2019, 09:22:15 AM »

Windbeam...original Pipstrelle was 34" span...but lets not get away from Applehoney's fine "Ellipsis".....the idea of low A/R is really appealing and I go that route when building for the small field my buddy and I use to fly on. We like to fly bungee on it and started to build 30" gliders and rubber jobs. Jims "Ellipsis" ticks all the boxes for that and just looks great.
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