treedog

Ijust saw this design online. It claims over 200 mph. Whatcha all think. worth scaling down?
Td http://www.west-wales-models.co.uk/s.../magnumr.shtml

combatpigg

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Treedog, those are neat planes but according to the German speed freaks who wrote the book on RC speed, no uncowled, side exhaust, 1.5 HP plane will do 200 unless you tie a rock to it and drop it from outer space. That goes for the Weston Magnum, too. Cool looking plane though and it would certainly be fast enough to put a smile on your face. I think it would be a good excuse for you to do a build thread............

treedog

CP Do you mean to say i might have been lied to by them dang english? heavens to murgitroid!!
Td[:-]

vicman

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I have seen a few of these bad boys cut up big blue. One with the whole Magnum combo. No two bills but totally cool nonetheless. I have even thought of scratching one for me-bad-sef. The best part of this plane is the cool whistle sound it makes.

combatpigg

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Td, don't change the subject, now get to building it!!! [>:]!!! We all drew straws and it is YOUR turn to do a build thread[don't forget to take lots of pictures along the way, too]

treedog

That's a fine idea CP but how do i scale down a wing spar out of foam? Any ideas ?[8D]
TD

combatpigg

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Td, I would just shape a 1/2A wing out of 1/4" thick balsa sheet. Let's say you go with a 26" span and the original has 40 inches of span, divide 40 into 26 and you come up with .65. Now all you have to do is take the full size dimensions and multiply them by .65 to do a rough scale job from a full size drawing. The other way would be to take a full size drawing to Kinkos and tell them you want 65% of the original. Now if all you can get is a small print out, them same procedure for scaling up can be used. For the sheet wing, I would inbed a full depth pine spar that is about half the span of the wing, and about 1/8x1/4 inch stock.

treedog

Cp, i knew you'd finally talk me out of that fine idea. T Kinko's finished that idea we ain't got 1.http://www.west-wales-models.co.uk/shop/frankenmodellbau/index.shtml
TD Here'S a 235 mpph plane.

ptulmer

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Kinkos, we don't need no stinkin' Kinkos! Build a box fuselage just big enough for the radio, add a turtle deck and canopy. Eyeball the outline of the wing in 1/4" and tail in 1/8" thick balsa. BTW, the easy way to do a spar for a SWR is go grab a 1/4x1/8 basswood. Join two sheets of 1/4" with the basswood in the middle. BW is light and strong, second only to spruce for this purpose. Oh, and far straighter that spruce! Layout the wing outline so that the airfoil high point is over the BW spar.

vicman

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How about the cool whistle noise? How do it work? I think there is a relationship with the top of the tailplane being higher than the trailing edge of the wing and the trapped air in the anehedreal of the tail.
Dunno but it sounds like it's tearing a hole in the time space continuom. I know a high power rocket guy who has a airflow whistle trick with the fins but he hasn't ever given me the whole story about how it works and what he does.
It's actually more like a whine than a whistle.

Raymond LeFlyr

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Vic,

Are you sure that the whistling sound you hear isn't somehow related to the "anhedral" between your ears?

ptulmer

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Vic, I bet it's servo arm slots. My Interceptor made a loud whistle that sounded really neat. We traced it down to the slots being positioned just right and the wind hitting it just like blowing into a whistle.

vicman

My Feedback: (10)

Raymond, you may be onto something. But I only hear it when I am looking up at one of these planes and not any others.[sm=72_72.gif]

PT, the sevos and linkages are internal. I think you have found my wish list for your next design
FWIW, the blink is nearly ready for fun. Once I clear two projects that are very near completion your delta is going back into rotation for completion.

MJD

My Feedback: (1)

Ah, the sound of drag... my Magnum does it too. Goes for high power rockets too. Some big fat draggy designs sound wacked when the motor cuts out. A member of the local club has a big fat 8" rocket with 6 tube fins and you can hear that thing a mile away when the motor cuts at speed. Mind you lots of things whistle and shriek at 500mph+.

Treedog, like CP said, Magnums do not do 200 mph. But they're not dogs either. Apart from the fact that it looks kind of cool, there is really nothing special about the aircraft's design with the exception of the thin wing airfoil. It's a small model with a lot of power = pretty fast. But aerodynamilcally it is not too refined. The tail surfaces are oversized with blunt leading edges and in the case of the vertical stab a square trailing edge. The wing sweep is unnecessary but of course looks neat. The canopy is fiberglass, and could have been designed as a nifty pipe tunnel for RE engines, instead the pipe hangs out like a drag brake.

With that out of my system, I would say that a 16-18" version on a honking 1/2A would be a fun wee project. Go for it!

If you want I can sketch out the basic planform for you - lemme know. I have one unassembled and it wold take mere minutes to do so. Besides, if I did that I could draw little ones too for fun.

MJD