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Dec 31, 2019, 06:41 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
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Jan 01, 2020, 04:05 PM
B for Bruce
BMatthews's Avatar
Install the tail wheel in line with the fin's hinge line and install a brass tube with a tiller wire. The tiller wire is "U" clamped to the lower side of the base of the rudder. Steering done.....

And just losing the nosewheel will help a lot with less risk of coming out nose heavy. Also don't just look at the engine weight when doing a comparison. There was the mount used by the engine and the muffler for it and the fuel tank which even empty was about an ounce. All things you won't have with an electric motor and conventional gear. Also motors that make the same sort of power as a .15 to .25 tend to be lighter than the engine anyway. So coming out nose heavy is not really all that likely. In fact I'd be surprised if you don't need to position the flight battery pretty much where the fuel tank normally went.
Jan 01, 2020, 04:54 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Great information Bruce, thanks.

Flying buddy I talked to the field today has the plans so I'll be able to trace out the fin and rudder (although it looks real simple).

I swapped the reverse shaft motor for a same-weight motor with a conventional shaft, it weighs 132 grams so with a 9 inch prop on 3S maybe I can get 300 or so watts. I need to bench-test, I don't know the kv rating. Maybe I can do a magnet count or something else to figure that out. For this motor I only need to cut off about 1/2 inch off the nose with the included collet.

I figure worse-case the all up weight will be 3.5 pounds. Clipped wing area is 357.75 sq in. Wing values:
WL: 22.5 oz / sq ft
WCL: 14.3 (falls in-between scale and racer range)

It still has a flat-bottom airfoil so more lift.

It will be very interesting to see how this airplane flies.
Jan 01, 2020, 06:01 PM
Registered User
I don't see why this plane should be so heavy. It should be possible to build it to 2.5 pounds without difficulty, and that's with a glow engine. My Livewire Champ, built from a Midwest kit with a bit of lightening and mostly stock came to 2.9 pounds and it had a 55 inch wingspan and 590 sq inches. It flew great with a .15.

Be careful using wing loading. It only works to compare planes of similar sizes. I think a full scale Piper Cub has a wing loading of about 25 POUNDS per square inch. Why doesn't it fly like a brick? Because at that size the wing loading is quite light.

Your plane would fly fine at that weight, but it would be on the heavy side. Take a pound off a plane that size and you will really notice the difference. Set your sights on a lower weight.
Jan 01, 2020, 06:20 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
The weight I estimated was putting the airplane and all parts (including power and radio gear) on a scale. It may come in a bit lighter, but it was a bit over three pounds. The original builder built it heavy.
Jan 01, 2020, 06:29 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
One more thing...

Scale was an old analog dial type, capable of weighing maybe 15+ pounds, so it may have had some calibration issues. I'll drop everything on to my digital scale and report back. Hopefully it comes back lighter.
Jan 01, 2020, 07:08 PM
B for Bruce
BMatthews's Avatar
I do recall that the weights of the student built kits way back varied by a lot. Depended somewhat on the wood in the kit but as much or more on how heavy handed the builder was with glue and "stuff". But at least with the stock wing they all flew surprisingly well. I'd expect this clipped version at 3.5 might have an issue or two but then again it might be just fine.
Jan 01, 2020, 08:50 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Well, maybe I wasn't reading the scale right (parallax issue?)...

It weighed 2.6 pounds on my scale, so WL comes in at 16.9 oz / sq ft, WCL 10.7. That's much better.

Buzzard bait had it nailed as far as expected weight.

I'm going to put future posts here:
https://www.rcgroups.com/forums/show...berg-Eaglet-50

Thanks for all your feedback.
Jan 11, 2020, 01:35 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
I was just informed the thread I continued posting was in fuel planes, so I'll post over here now.
Jan 11, 2020, 01:41 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Work continues, right cheek side built up. I'll need to carve out some of the material on the left side to allow the motor to be set. I will leave material that I can, including the covering over the motor. With proper holes and one section of monokote cut out on the bottom of the fuselage in the rear area I should have plenty of ventiliation.

Measurements show I need 35 mm standoffs to get about 5 mm clearance.
Jan 14, 2020, 02:17 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
The nose area is complete, got the first round of filler applied.

Need to work the electrics and get the motor mounted before I apply final coat of filler and add monokote. Got some bright red to cover the UT orange...

Lots of stuff still to do, including bolt-on wing, create fin, cut out control surfaces, electrics, elevator and rudder servos, covering. I'll pick away at it and look for an early spring maiden.

I gotta get going on a SUD Caravelle that has been in planning for over two years!
Jan 14, 2020, 06:38 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
With the windows being open, I'll hold off on cutting out monokote on the fuselage bottom. Plenty of ventilation!
Jan 16, 2020, 06:41 PM
TAFTS
Its not balsa but I built a little Eaglet from foamboard. Here is the first post. I may do a build thread in my blog later.

https://www.rcgroups.com/forums/show...3#post43615007

Scott
Jan 20, 2020, 07:21 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
I created the standoffs from Pex, they seem to be real strong. I'll post a picture when I have the motor permanently mounted. 4 degrees down, 1 degree right as measured in the plans. The Pex was cut with slightly different lengths to get the thrust angles right.

I decided to use hold down bolts and a dowel instead of rubber bands to secure the wing. Used some ply to attach the assembly to spars, then filled in the gap from the wing bottom to the dowel with some layered balsa glued together. Cut a channel for the dowel, it is tight and will hold down the block while the glue dries.

The fin construction is the only surface I needed to pin down, as all the others are built. It is glued up.
Jan 25, 2020, 08:04 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar

Wing Mounting Question


As I stated earlier, I'm going with wing bolts and a dowel for the Eaglet.

I wanted to see if I could get some recommendations for attachment points for the bolts. They are 1/4 20 nylon bolts, with large heads, making them easy to turn. I have some 3/16 hardwood I'm figuring will work well, not sure what it is. It would drill nice, even at an angle then tapping and using ca to harden the threads. I also have some hardwood stock that is much thicker and square, that might provide more gluing surface.

I can't run a piece across the back of the opening, the aileron torque rods need every bit of space, and I don't think I could bend them and get the movement I need. I could run pieces along the side, maybe about 20 mm. I'm concerned about the strength. There is a bulkhead right behind the opening, but I don't want to compromise it by running the wood through it. It may be possible to embed a dowel in the end and run that through the bulkhead.

Thanks.
Last edited by ruff1; Jan 25, 2020 at 08:09 PM.


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