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Old Feb 22, 2012, 06:53 PM
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New Whale & Aerobatic/VTPR Thoughts


Last year around this time I was enjoying my share of moldie whistles and killer pumps as usual, but I wanted more. In the past, I remember flying a friend's kulbutin and not really "getting" it. I kept thinking about it and wanted a foamy version. Something a little different. Something dedicated to aerobatics and not speed or maniac pumps. I still love that stuff, don't get me wrong. I just wanted a thinking man's plane.

I came across the Madslide Plans and gave them to Dan. Through Dan the Madslide evolved into his extra kit. I quickly built this thing and was soon enjoying effortless inverted flight, flips, spins, and more.

Pictured is my evolution of slope aerobatic planes.
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Old Feb 22, 2012, 07:08 PM
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New Whale


Currently I'm really enjoying my DoDo design, but I like building...

The New Whale, or whatever you want to call it started with a 60" EPP wing with a slender TP42 airfoil. I cut the templates and took them to the EPP cutting master, Dan. He cut the whole airfoil including the planned 2.25" ailerons.

The construction so far is very similar to the Multifun. It uses EPP for all control surfaces. This EPP is very important for me for durability reasons.

So far everything is weighing 16oz. I'm guessing I won't go over 25oz.
Old Feb 22, 2012, 08:44 PM
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HaHa, I think Cliffhanger affectionately called my Dodo the D1LDO.
Last edited by Big Gas; Feb 22, 2012 at 08:47 PM. Reason: picture
Old Feb 22, 2012, 08:48 PM
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I've seen the video of the Dodo in action, and judging by the fact you're building another version of that forward-biased fuse shape, care to elaborate on your findings to date?

What's better about it vs. the more fishy shapes common to previous designs? Drawbacks (maybe more drag? Hard to say though since frontal area is not really influenced too much). Surely getting it CG'ed is easy and I have to imagine it's quite resistant in a crash!

Steve
Old Feb 22, 2012, 09:01 PM
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Originally I was going for a dolphin fish type look, mahi mahi, or dodo as some call it.

Everyone says it looks like a whale though.

I don't think drag is much of an issue here. In the design I was thinking it would make the nose tougher for those nose ins, it did, and keep more mass ahead of cg, I didn't add any nose weight.

The fuse are actually offal pieces from Dan's work. A slight cut in the nose made the whale shape. The moment may change a bit. This is a variable I really like to play with.

The big thing I wanted to think about here was incorporating the TP42. I also wanted to play with EPP tail feathers as I really like them on the Multifun.
Old Feb 23, 2012, 12:11 AM
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So do you notice a difference in knife edge performance with this fuse shape versus the more fishlike fuses of the other aerobatics gliders you've flown? Or the Madslide/Extra (I find the Madslide shape has very good KE authority)?

Steve
Old Feb 23, 2012, 02:38 AM
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Looks like a Humpback to me!
That's quite some side area ahead of the l.e.
Love the nice big rudder.

Good question by Steve there, ref knife edge flight- looking forward to seeing some video.
Old Feb 23, 2012, 05:12 AM
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Dare I say...
"Hope you have a whale of a time flying that"

I think "Moby" might be a good name for it?
(plenty music to choose from then - or there's always Nantucket Sleighride)

Phil.
Old Feb 23, 2012, 10:02 AM
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It immediately reminded me of the Hotspur I built back in 2003:

https://www.rcgroups.com/forums/showthread.php?t=149751

Anyways I would love to get John's impressions. I still think the ideal fuse shape for this kind of flying remains to be discovered

Steve
Old Feb 23, 2012, 11:47 AM
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A knife edge pass on the slope has more to do with the speed and energy of the model prior to entering the maneuver. I think the shape of the fuse/ rudder design help, but the speed is more important to sustain knife edge. My Extra could hold a fairly decent knife edge with its weight behind it, but nothing like the 200-300' passes with my loaded 70oz. minivec in 50mph wind. Use of the rudder is also important too. If I bash the rudder stick on my Dodo, it will simply pop its nose up (which is actually pretty cool) slow and stall. If I milk it, on and off, a more elegant KE will occur. I am a particular fan of the "suicide" KE, where the nose points to the ground. Enter KE the same, with speed, slight nose up, roll, and then opposite rudder. I usually roll over inverted to exit.

One of the main goals with this fuse shape, in this case something like a cricket bat, is to offset or perhaps balance the rudder. In particular during a flat turn, or in a knife edge slide toward the ground, ie the model rides an "elevator" down with the wings perpendicular to the ground.

Tail moment is also an important thing to consider here too. We've found with Gary's night nobler, with its short tail moment, and large rudder, that it just acts as an airbrake, instead of offering any sort of nice yaw movement.

Steve, I like the looks of your old Hotspur. I have a shark fuse that needs to fly.
Old Feb 23, 2012, 12:13 PM
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This was the third (and last!!) of my "X-centric" prototypes to investigate K.E flight.

It's as ugly as sin and has been likened to an industrial"wheelie bin" by one flying buddy!
It makes John's Whale look quite handsome.

The wings are from a Guppy and the fuselage is a TP42 airfoil.

It flies well, one day I'll take some video. It'll probably be rated "XXX"

Last edited by cliffhanger; Feb 24, 2012 at 02:26 AM. Reason: picture addition
Old Feb 23, 2012, 12:18 PM
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Yikes!

*off for a cup of tea and a sit down to recover*
Old Feb 23, 2012, 05:12 PM
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Here's a question/thought re. longerons. Wouldn't the use of tapered carbon graphite tubes(ie. fishing rod tip sections) help decrease mass in the tail while still providing adequate and progressive stiffness to the fuselage as the taper enlarges towards the nose? Same potential gain for wing spars??

Ken W.
Old Mar 12, 2012, 11:39 AM
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TP42 Tested


Quote:
Originally Posted by Snewk View Post
Here's a question/thought re. longerons. Wouldn't the use of tapered carbon graphite tubes(ie. fishing rod tip sections) help decrease mass in the tail while still providing adequate and progressive stiffness to the fuselage as the taper enlarges towards the nose? Same potential gain for wing spars??

Ken W.
That's a good idea, but aren't tapered tubes more expensive?


Quick and dirty, I put this wing on my multifun.

WOW! I found my airfoil and foamy wing construction technique. I really liked the performance. We thought this thin foil was going to be a little too fast but were nicely surprised at how slow it would fly or hover if wanted. I put it through a number of "VTPR" maneuvers and really enjoyed. Weight came in just under 20 oz. and the durability is solid. One of the best parts was the lack of flutter, YEAH, when at terminal velocity or during quick outside loops. Flips were not as impressive, do to the standard elevator, yet still fun and "sorta" on high rate.


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