A moderately high AR plank flying wing - Page 4 - RC Groups
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Feb 28, 2017, 03:52 AM
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Carolynne's Avatar
Hi Col!

Its great to hear from you and I hope to catch up soon in person! Perhaps at Jerilderie?
Thank you also for your compliments. I am very happy with the Calliope as it comes together and I am currently getting very anal about fuselage to wing fits and am about to do the sculpting of the fillets as they extend onto the rudder. Such fun!

The funky looking fin and rudder was meant to move the area as far aft as possible while keeping most of it disposed around the vertical CG. Hence the sweep. Another reason for the sweep was taking into account something Mr Rutan did in designing the winglets for the Long Ez. In essence, what he did was to use the pressure peak from the winglet to 'fill in' a separation prone area near the wing trailing edge. The idea behind the highly swept fin growing out of the fuselage just ahead of where separation caused by the wing fuselage junction is probably having a party, is to fill in that separation and hopefully reduce overall drag and also keep the elevator response reasonable at high A of A. Anyway, the reason for all this lecture is to say that I think that I'll try the rudders as is at first, but since they are going to be tape hinged, it will be the work of seconds to rip them off if I need to.

I would love to hear your thoughts and experience about the Horten / Pioneer setups and also your thoughts on negative differential. As mentioned earlier, I have found that it does seem to straighten things out, and am comfortable in setting things up that way if necessary, but I would love to get other's perspectives as well.

On another tack, I have also been looking at some of the European experience in using crow braking on plank style wings with separate elevators and ailerons. It certainly seems to work nicely and offers another form of braking.

Best regards

Carolyn
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Feb 28, 2017, 11:29 PM
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EdSoars's Avatar
"On another tack, I have also been looking at some of the European experience in using crow braking on plank style wings with separate elevators and ailerons. It certainly seems to work nicely and offers another form of braking."

Care to share any of those references? I just finished programming the separate ailerons and elevator of my Tiger Moth for the same thing. After all, it would be a waste of a 3-servo wing and a programmable transmitter to not try a crow braking system. I put the elevator on a left-side slider and the ailerons on the right-side slider. This way I can get some altitude, and try both to find a proportion that doesn't produce a dive or a loop... hopefully before hitting the ground.

Now if the snow will kindly stop falling...
Mar 01, 2017, 03:48 AM
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Carolynne's Avatar
Hi Ed,

Unfortunately I don't keep references and links handy ( or at all for that matter!). But, I do recall that one of the examples of crow braking on planks that I saw was an aeroplane named Tiger Hai ( Tiger Shark). I know this because I was given the article ( in German) from FMT for this aeroplane and I've also seen videos of it doing its thing. There are others showing the crow braking and I'm sure you'll find them on youtube , vimeo etc.

I'd be interested on your thoughts too!

Carolyn
Mar 01, 2017, 07:46 AM
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Hi Carolynne
You have buils a sexy flying wing, and have created a good topic to while away the hours.. Here are some more ramblings to add to the subject

Jim Marske is the Pioneer man. Interesting guy, does stuff in a practical way with not too much maths to complicate things.. He did a book in the 70's i think that made good reading. His wing layout was the same as yours, but not so high aspect ratio, so some things may not flow over. He too talked about differential, and concluded that it needed to be reversed a bit to get a no pitch in turns situation. In your situation you are likely to have more adverse yaw so a compromise might be necessary, or you may get to lead with some rudder. Im guessing you will get quite a few mixes going... much easier to do than with levers as full size.
Enjoy your build.. nice to watch. I think the test flying will be quite exciting, but rewarding eventually
Col
Mar 01, 2017, 09:25 AM
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EdSoars's Avatar
Carolynne, I found a few photos and videos just with simple searches in RCG, showing crow deployed that gave me a starting point. It looks like my TigerMoth planform with central one-piece elevator should work. The real trick is to estimate the difference in deflection between the elevator and the ailerons. I will start with full down elevator (about 40 deg) and half up-aileron (about 20 deg). This will be activated by the throttle stick. Separate trim for elevator and ailerons will be on side sliders so I can tune in-flight. I'll post bench photos a bit later today and hopefully flight video later today weather permitting.

ed
Mar 01, 2017, 06:14 PM
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Carolynne's Avatar
Hi Col,

I agree that the first flights of the Calliope are going to be more than usually exciting. This has been preying on my mind and so I've been doing a little bit of forward planning:

Firstly, I live on a few acres of grass that is surrounded by many kilometres of the more grass. This means that when the wind blows, even when it is strong, it is remarkably smooth. This should allow me to use my backyard as a bit of a wind tunnel and so let me get an idea of the trim and control effectiveness without letting the aeroplane get too far from my grasp.

Also, I usually mow large tracts of grass to keep things neat, make walking easier and also to keep fire and snakes away. However, I've recently let a section grow until it is now about thigh deep. Hopefully this will be a nice cushion if things don't go perfectly the first time I let go....

Anyway, this is incredibly premature as not only do I still have to finish the airframe and install all of the bits and pieces, but I also have the major and vexing issue of colour scheme to address..... White? Black? Black with light blue?Stripes? Mosaics?

Carolyn
Mar 03, 2017, 09:59 PM
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In the "old days" long grass was a pre requisite for test glides !. Might even be worth sneaking out before its painted !
Mar 04, 2017, 09:13 PM
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Carolynne's Avatar
I am so glad to be accessing "ancient wisdom" in my long grass cushion.

C
Mar 06, 2017, 03:28 PM
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EdSoars's Avatar
The most magnificent maiden I ever did was years ago with a 4m Alpina, standing on the passenger seat of a convertible Corvette Stingray. No grass, no snakes, but plenty of speed.

You have some nasty alternatives: no cushion with no snakes, or long grass with the snakes!
Mar 06, 2017, 07:40 PM
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Carolynne's Avatar
Hi Ed,

So, what you're saying, is that in addition to all of the other things that I look for in a man, he has to have a convertible car (preferably a "Corvette Stingray")???? Somehow, I think that I might be accused of being just a little 'picky'

Anyway, I have a nice bunch of snakes around here, mostly brown and tiger types, with whom I have a tacit agreement: If I don't scare or surprise them, then they won't try to eat me.......usually. Also, the weather is starting to cool off and so the snakes and other 'bitey' types are becoming less active, so traipsing around in the long grass should be OK by the time I need to.

Carolyn
Mar 07, 2017, 12:30 AM
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EdSoars's Avatar
Oops! Umm, er, that "Maiden" was a test flight!

But holy cow, that was fun. And it was a fun old car, too. 1969: last of the high-compression engines. At 123 mph it transitioned between a very good car into a very bad airplane. The front end would get light and start hunting. And the sound of that big V8 at 5500 rpm. Tuned intake and exhaust headers. Oh glory!

There's no Smilie for wistful. Still, I wouldn't trade that then for the fun I have here now.

ed
Mar 14, 2017, 10:30 AM
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Quote:
Originally Posted by EdSoars
Oops! Umm, er, that "Maiden" was a test flight!

But holy cow, that was fun. And it was a fun old car, too. 1969: last of the high-compression engines. At 123 mph it transitioned between a very good car into a very bad airplane. The front end would get light and start hunting. And the sound of that big V8 at 5500 rpm. Tuned intake and exhaust headers. Oh glory!

There's no Smilie for wistful. Still, I wouldn't trade that then for the fun I have here now.

ed
You don't like the latest generation of Corvettes?

My next car will be a used "modern" Vette of some type. The important variables are V-8 with too much torque/power, and a manual transmission.

I tried convincing the boss ... err ... wife ... in 2010 that the new car was to be a Vette. The kids were littler then, so I was not persuasive. I ended up buying a 2010 (new) Honda Accord with a potent 2-something-liter 4 cylinder. (I can hear you laughing) The Accord does have a manual transmission though, and the suspension is nice (double wishbone arrangement up front). Do you know how difficult it is to find a Honda Accord with a stick shift?? There were a total of 3 in Maryland at the time I bought.

I can just imagine driving a Corvette in your neck of the woods (curvy secondary/tertiary mountain roads). Oooh.

-Dave
Mar 14, 2017, 12:05 PM
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EdSoars's Avatar
Did I cause "topical drift"?

You can't drive a Corvette at anything like its performance level with safety on our roads: tourists, deer, elk, all are safety hazards lying around the next seductive bend in the road.

I've become a pickup guy. I can haul more gliders in it over rough terrain to the beloved slopes.
Mar 14, 2017, 02:07 PM
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Quote:
Originally Posted by EdSoars
Did I cause "topical drift"?

You can't drive a Corvette at anything like its performance level with safety on our roads: tourists, deer, elk, all are safety hazards lying around the next seductive bend in the road.

I've become a pickup guy. I can haul more gliders in it over rough terrain to the beloved slopes.


I *do* have one of those. We use it to haul our travel trailer.

-Dave
Mar 15, 2017, 01:00 AM
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Carolynne's Avatar
While you guys talk amongst yourselves, I'll just get on with the Calliope...

Happily, I now have a custom spinner that matches the original contour of the nose. Likewise the electric motor has turned up and so the next step is to slice of the nose and get all of the whirly bits to fit. ( fear and trembling at the thought of maybe ruining the fuselage!)

I still need to finalise the Dodgson coupler for the elevators and then the wings are ready for a final sand. And I still haven't decided on a colour scheme.....


Carolyn