Aegea TD toy

[VE6WEM]

Here’s a picture of my Aegea. The wings are supposedly from Phil Barnes (I bought the plane used) and are the heavy duty F3J layup. They had better be since they weigh 45.3 oz. with servos and joiners. Built to plan, the tips have 5 degrees of dihedral and the center section is flat.

I have added the wing to my own pod and boom fuselage with a tailboom.com heavy Bubble Dancer carbon boom. Though a little soft for my preference, the boom will be adequate since this is a low speed model. The tail has my version of the V-mount full flying stab, tail surfaces are bagged FG on pink 250 foam and uniweb carbon spars with weblets. The rudder has a Kevlar hinge.

Pushrods are 0.050” CF in 16 ga. Teflon tubes. The wing is bolted on with two 10-32 bolts.

Design wise, I have gone to a long tail moment with minimal tail area coefficients. Once you get used to the lower control power, the low speed handling can be smoothed out a lot with some practice.

All up flying weight is under 66 oz., if you don’t think a 19.4 oz RTF fuselage is light, go and weigh your own 130” open class fuse. I can save another ounce by using an Electron Rx instead of the Airtronics PCM Rx.

After a few hand tosses, I flew it on the winch in light winds. In comparison to my own TD designs, the plane is quick for the all up weight and wing loading. Landings are slow, but if 10 ounces could be taken out, it would hang on the wing like my Supergees.

I’m sure that the Aegea 130 would probably be a more popular plane if it were not an exercise in gathering parts from a multitude of suppliers or scratch building everything but the wing. A lighter bagged wing with a proper carbon spar should come out at least 6 ounces less and this may be an advantage since the airfoil is designed for these low Reynolds numbers. After this flying season. I’ll decide if the weight reduction is worth the effort to build a new plane.

[Ollie]

A 130 inch span Aegea wing built to Dr. Drela's specification should only weigh 25 ounces.

[pteromorph]

To compare weights:
http://www.rcgroups.com/forums/showpost.php?p=1916588&postcount=63
I am sure a 3m TD of the same genesis would be VERY attractive. Maybe FATHER (http://www.polecataero.com) is working on it...

[VE6WEM]

A 130 inch span Aegea wing built to Dr. Drela's specification should only weigh 25 ounces.

I agree, that's why it may be worthwhile to build a new wing with a proper spar. Guessing at the servos, wiring and hold downs, this wing weigh approx. 38.5 ounces. I have built much stiffer wings at 134" that weigh less than 29 oz. with joiners and wing bolts.

As far as the Skydancer, I have one of those too. The structural requirements of F3J towing make the material choices and contruction of the Skydancer inappropriate.

[briandlg]

very nice looking bird. i've been toying with the idea of putting together a aegea mantis after i complete the supergee i'm working on, but after seeing your pics i may just come up with my own sort of fuselage/pod contraption. i would *love* to have a 130" wing, especially with the sort of weight that people have been bringing their mantis' in at (usually between 60-70oz). i do know that phil has been doing some mods to the aegea wing to make it stronger, what i wonder is if the current aegea wing (found at the allegro-lite list page) incorporates any of those strength improvements that people have been doing. it may be lighter per plan, but is it strong enough?

[Ollie]

It is my understanding that Phil Barnes is using the aerodynamic design but not Dr. Drela's structural design. The Barnes structure is less labor intensive and thus less expensive to produce but heavier.

Dr. Drela's Aegea wing structural design is to stiffness rather than strength criteria. As a result it is about twice as strong in bending as it needs to be. You will be very hard pressed to find either a better aerodynamic (high L/D) or structural (high strength to weight) design than Dr. Drela's.

[briandlg]

that's what i wanted to hear! i don't mind labor intensive. :)

I would love to see some more detail pics of your fuselage...how did you attach the wing?

[Les Horvath]

Here’s a picture of my Aegea. The wings are supposedly from Phil Barnes (I bought the plane used) and are the heavy duty F3J layup. They had better be since they weigh 45.3 oz. with servos and joiners. Built to plan, the tips have 5 degrees of dihedral and the center section is flat.

I have added the wing to my own pod and boom fuselage with a tailboom.com heavy Bubble Dancer carbon boom. Though a little soft for my preference, the boom will be adequate since this is a low speed model. The tail has my version of the V-mount full flying stab, tail surfaces are bagged FG on pink 250 foam and uniweb carbon spars with weblets. The rudder has a Kevlar hinge.

Pushrods are 0.050” CF in 16 ga. Teflon tubes. The wing is bolted on with two 10-32 bolts.

Design wise, I have gone to a long tail moment with minimal tail area coefficients. Once you get used to the lower control power, the low speed handling can be smoothed out a lot with some practice.

All up flying weight is under 66 oz., if you don’t think a 19.4 oz RTF fuselage is light, go and weigh your own 130” open class fuse. I can save another ounce by using an Electron Rx instead of the Airtronics PCM Rx.

After a few hand tosses, I flew it on the winch in light winds. In comparison to my own TD designs, the plane is quick for the all up weight and wing loading. Landings are slow, but if 10 ounces could be taken out, it would hang on the wing like my Supergees.

I’m sure that the Aegea 130 would probably be a more popular plane if it were not an exercise in gathering parts from a multitude of suppliers or scratch building everything but the wing. A lighter bagged wing with a proper carbon spar should come out at least 6 ounces less and this may be an advantage since the airfoil is designed for these low Reynolds numbers. After this flying season. I’ll decide if the weight reduction is worth the effort to build a new plane.
Measure the thickness at the root of where the wing is joined (25%, 2.25")
with a caliper and let me know.
Les

[VE6WEM]

0.702". Should be 0.698". That's better than most can do. So what?

[briandlg]

i too am curious why you asked les?

[Les Horvath]

i too am curious why you asked les?
I wanted to know how accurate is the wing. You close.
Les

[RSCherry]

VE6WEM-

66 oz is pretty average for the 130" Mantis. Mine came in at 63.2, but I have a custom wing (made in the general style of Phil's design) that is 134". Of the 4 built, one came in at 61 oz by leaving off the bottom paint. We used a tube spar, like Phil's design.

I find mine to be a pleasure to fly- shows lift extremely well.

Bob

[VE6WEM]

RSCherry - I'd be interested in knowing what your wing weighs, servos, wiring and bolts included. Admittedly my wing tips are pretty light with only the single tube spar/joiner, the center panel is nice and stiff. Apparently there are two tube spars as well as top and bottom carbon doublers in the center panel. Phil's fit and finish is very good.

Thanks.

[RSCherry]

I'll check the weight of my wing tonight. Mine has only a single CF tube spar in the center section and tips. Mine was the first wing we built, and we found it was not stiff enough so I sanded the paint off the top of the center section and added 2 more layers of CF fabric. Subsequent wings still use the single tube spar. (this is NOT a Barnes wing, but made using his techniques by our little group)

For hardware- I'm using a 1/4-20x2" stainless steel bolt as a hold down, my single flap servo is (currently) a HS-85MG, and 2 HS-85's for ailerons. Wiring is somewhat heavy-22ga. antenna rotor wire stripped of it's covering and twisted, Deans's 4 pin connector.

I wouldn't worry about the weight- I can easily see this wing performing very well balasted up for a breezy day.

[RSCherry]

Here's my wing weight:

Center = 678g
Left tip = 226g
Right tip = 231g

Total = 1135g (39.9 oz)

[VE6WEM]

That's 5.5 oz. lighter in the wing, so under 60 oz. is a good RTF target for this plane. 55 oz. is probably achievable.

Thanks.

[markdrela]

my single flap servo is (currently) a HS-81MG, and 2 HS-81's for ailerons.


Yikes. A single HS81MG for both flaps? I think that servo will get a hernia on a hard winch launch. I'd go with an HS85MG on each flap as a minimum.

[RSCherry]

Dr. Drela-

Oops...my typo, they are HS-85's all around (previous post edited). Even so, I worry about the single flap servo set-up. I had a HS-225MG in the flap first, lasted one afternoon. The servo case broke internally as I dropped the flap to set up for landing (not a ground strike- in the air!). I've not had a problem with the HS-85MG, but I've also not winched this plane yet. May not get to see a winch until BRASS- not really where I want to be testing.

Which brings to mind a few questions-
1) What is the maximum moment around the flap hinge line on the 130" Aegea wing?
2) In general, what's the most effective way to approximate the moment created by control surfaces? Can I approximate this closely enough using some formulas from my old undergrad fluids book for flow around flat plates?
3) I've not used Xfoil- does it provide reasonable results for severe control surface deflection?

Bob

[nuevo]

Dr. Drela-

Even so, I worry about the single flap servo set-up. I had a HS-225MG in the flap first, lasted one afternoon. The servo case broke internally as I dropped the flap to set up for landing (not a ground strike- in the air!). I've not had a problem with the HS-85MG, but I've also not winched this plane yet.

RSCherry,

You tried a 225, it broke. So you replaced it with an HS85??? :eek:

Now you're using a single HS-85 for a 60" long flap with a 2+ " chord ???? :eek: I don't expect this servo to last either. :confused:


I've also not winched this plane yet.
This is key. Wait until you put that bird on a winch.

[RSCherry]

RSCherry,

You tried a 225, it broke. So you replaced it with an HS85???

This is key. Wait until you put that bird on a winch.



Just to expand a bit- the 225 broke and jammed in mid air at about 30% deployment on one of the first flights from a high start. Thinking back, that servo never felt right when it was installing it, either. It was clearly defective- Hitec has already replaced it, the new one is much smoother. The HS-85 was on hand, so I used it. While this might seem like poor engineering judgement, I made the decision based on what I had on hand at the time to get back into the air quickly. Let's face it, the difference between 44 oz-in and 55 oz-in is insignificant anyway if the problem does turn out to be excessive aerodynamic load. In that case I'll need 2 servos and a split flap, something I was trying to avoid to save weight.

No question the winch launch is the real test.

[nuevo]

Let's face it, the difference between 44 oz-in and 55 oz-in is insignificant anyway if the problem does turn out to be excessive aerodynamic load.

If it were plastic gears, I do know that the 225's have thicker gears, which would make them more durable. Of course you said both are MG's.

I understand about "using what you have". ;)

About the winch, my personal motto is to never try anything new at a contest. If you can find a winch before your first contest, get out and use it.

[markdrela]

1) What is the maximum moment around the flap hinge line on the 130" Aegea wing?
2) In general, what's the most effective way to approximate the moment created by control surfaces? Can I approximate this closely enough using some formulas from my old undergrad fluids book for flow around flat plates?
3) I've not used Xfoil- does it provide reasonable results for severe control surface deflection?


Xfoil is very reliable for predicting hinge moments. But as a worst case, the moment can be closely approximated by the following formula:

M_hinge = 0.25 * (flap_area/wing_area) * Lift * flap_chord / CL

This applies to large flap deflections where the flow over the flap is separated or nearly separated, such as with a 10-15 degree flap setting on launch. For the Aegea flap:

flap_area/wing_area = 71/1062 = 0.067
Lift = 150 lb
flap_chord = 2.4 in
CL = 1.2
M_hinge = 5.0 in-lb = 80 in-oz

The servo moment will be smaller than this due to the servo/flap "gearing":

M_servo = M_hinge * (servo_arm/flap_horn_arm)

This depends on the servo arm/horn ratio you have, but my guess is that

servo_arm/flap_horn_arm = 0.75
M_servo = 60 in-oz

Fairly hefty, but not too bad. Note that Lift = 150 lb is a VERY hard launch.
In any case, an HS85MG should be able to hold this moment without trouble.

[RSCherry]

Dr. Drela-

Thanks for the quick reply. You already went to my next set of questions, bringing in the 4-bar linkage that is the servo arms and connecting rod.

It seems to me that the servo torque requirement varies depending on where (geometrically) the servo arm and flap horn are for a particular flap deflection, as well as the ratios of arm lengths. Since the true moment about the servo or hinge is dependent on the "effective" moment arm, I was considering looking at this on , say, 10 degree intervals to detect the peak. If Xfoil can easily provide me with the flap moments at 10 degree intervals, it's an easy task to draw the 4 bar link in AutoCAD and determine the servo torque at the 10 degree intervals.

Bob

[SoarNeck]

Bob - send me a PM with your email and I'll send a spreadsheet that will do this for you.

Warren - nice model! Be sure to bring it out on Saturday if you can. I'll be a little late for the DLG clinic, since the earliest I can make it would be 11:30.

[VE6WEM]

Well I had a chance to get some extensive thermal flying on the Aegea today, the lift was weak in the morning and built to boomers later in the afternoon. Launch trim is strange, I have the towhook right on the CG and should be ¼” behind that to get rotation. With some compensation of up elevator trim on launch the plane still gets a decent launch though not as strong as my MH32 designs.

What is more impressive is the cruise mode with recommended amount of reflex. No other plane I have built has as much pitch response to reflex. Once 8% down trim was programmed in, the speed range of the plane increased to the point where everyone was impressed. As the wind picked up to about 15 mph in the afternoon, no ballast was needed as the plane still came upwind at a good clip. As a TD style plane you can now see the advantage of 8 ounces out of the plane since the top end would be more than adequate at 56 ounces, while the thermalling capability would increase. This is very nice ranging plane that can thermal with the best of them, there’s no observable performance difference today while flying against the Icon, Pike Superior, Artemis, Eraser F3B and Extreme that showed up. But then again, they do say it’s the pilot not the plane :)

Next is the landing mode setup, getting a flap/crow/elevator setup to work, though the one landing measured today was a 97.

[markdrela]

With some compensation of up elevator trim on launch the plane still gets a decent launch though not as strong as my MH32 designs.

Are you using launch camber?. I'd go with about 10 degrees, full span.

[Badger]

del