#Tag · bonfire.cafe

The glider now has 12 pounds of lead shot and epoxy added to dead space in the very end of the tail boom.

My initial estimate of volume indicated that I could add 8 - 10 pounds this way. I'm pleasantly surprised, and I didn't make a chocolate covered mess of things as I was pouring this goop into the tail.

I need to add a few more pounds to the tail. Phase two of this project will use lead plate, bolted to the vertical fin spar. (I need to unroll the 1/4-inch plate first, then develop a template to cut the lead.)

I could not add the epoxy/lead shot mix all at once because of the exothermic reaction of epoxy. When mixed epoxy is in a thick blob (instead of a thin layer), it generates enough heat to warm itself...which accelerates the chemical reaction...releasing more heat...further accelerating the reaction.... I have seen epoxy smoking hot because of this, so I added a bit, waited a half hour, checked temperature with an IR non-contact thermometer, added a bit more when it was clear that the exotherm was only very mild, etc. That took a while, but turned out well.

I note that Roto Metals has a discount on some 1-inch lead plate. Get your fork lift ready. No free shipping!

https://www.rotometals.com/lead-sheet-plates/sheet-lead-1-64-lbs-sq-ft/

#AvGeek #Aviation #ElectricAircraft #Homebuilt #Glider #DIY #EAA #Ballast #Math #Density #Exothermic #Chemistry #Thermodynamics #Lead #Epoxy

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A view from inside the tail boom, aft of the tailwheel, looking aft. A Plexiglass dam was caulked into place as a 'dam' to hold the lead shot and epoxy mix. I was able to fill up to the dam, then top off with extra epoxy. The lead shot is dark gray and most of the tail boom interior is carbon fiber...black.

A view of the very end of the tail boom, looking forward. Two dams on the sides of the tail boom's circular cross section are holding back several pounds of lead shot and epoxy. The ends of the rudder cables are wrapped in blue tape to keep away epoxy.

Dark gray lead sheet, 1/4-inch thick, needs to be unrolled and then cut into rectangular sections and bolted into the tail for further ballast.

Do you need any 1-inch thick lead plate? Cheap at the price! No free shipping!

https://www.rotometals.com/lead-sheet-plates/sheet-lead-1-64-lbs-sq-ft/ — Do you need any 1-inch thick lead plate? Cheap at the price! No free shipping! https://www.rotometals.com/lead-sheet-plates/sheet-lead-1-64-lbs-sq-ft/

Lead Sheet / Plates - Sheet Lead 1" ~64 lbs./SQ FT - RotoMetals

TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

@KrajciTom@universeodon.com · last month

Where is the center of gravity of the empty glider located?

If you measure the location of the main wheel and tail wheel (reference to something such as the glider's nose), and the weight each of them carry...you can do the math to answer that question.

Where is the center of gravity when the pilot is in the glider?

Climb in, and then take the same measurements.

Now I know if I need to add trim weights to the nose or tail, and how much.

Determining center of gravity location is critical for safety of flight and good handling characteristics. I'll do these measurements and math more than once so I can be very confident of the results.

#AvGeek #Aviation #ElectricAircraft #Homebuilt #Glider #DIY #EAA #Aerodynamics #Math #Mass #Weight #Balance #Safety

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The glider is assembled and ready to be weighed at both wheels to determine the center of gravity location. Wing stands hold the wings level.

The main gear sits on an electronic measuring scale.

A home made ramp that allows me to roll the glider onto the scales. This ramp has a very shallow angle so that it does not take much force to get the glider up the ramp. This ramp is over five feet long and lifts only about 2-1/2 inches.

Yellow wooden wheel chocks sit on the ramp, ready to use. — A home made ramp that allows me to roll the glider onto the scales. This ramp has a very shallow angle so that it does not take much force to get the glider up the ramp. This ramp is over five feet long and lifts only about 2-1/2 inches. Yellow wooden wheel chocks sit on the ramp, ready to use.

TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

@KrajciTom@universeodon.com · 2 months ago

Gliders often go to significant lengths to reduce drag.

My flaperons are driven by a push-pull tube that exits the wing skin and pushes against an external drive horn. There are two of these setups on each wing...four external devices that need fairings.

But they and the flaperons move. That complicates things.

First photo shows one push-pull tube and drive horn without fairings.

Second photo shows the inner/smaller fairing that will eventually be glued into place.

Third photo shows both fairings in place and the flaperon near the limit of its down travel.

Fourth photo shows both fairings and the flaperon approaching the limit of its upward travel.

One fairing of the two pairs on one wing are drying overnight. Tomorrow morning, I will make final adjustments to the remaining inner fairings and then glue them in place.

I'm using RTV silicone, which needs humid air to cure well. It's winter in New Mexico and the air is super dry. I have put a very large pot of water on the wood stove to humidify the air overnight.

#AvGeek #Aviation #ElectricAircraft #Homebuilt #Glider #DIY #EAA #Fairing #Drag #Aerodynamics

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The flaperon push-pull tube exits the wing skin and is connected to an external drive horn on the flaperon at the trailing edge of the wing. This needs a fairing to reduce its drag. (Beyond the wing's trailing edge is shop clutter and equipment. On the wing is an old pink towel and a pair of left-handed scissors with orange plastic handles.

The aft (smaller) fairing is temporarily held in place with blue tape. This is only half the battle. We also need a fairing on the forward part of this assembly.

Both fairings are now in place. The forward (outer/larger) fairing has been glued to the wing's surface. The flaperon is near the lower limit of its travel.

Both fairings are in place, and the flaperon is near the limit of its upward travel.

TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

@KrajciTom@universeodon.com · 3 months ago

This video shows the flapperons moving as camber-changing flaps. The two control surfaces move in unison. My flap control system has five settings. The central setting is flaps zero or flaps neutral. Two settings increase the camber more, which is suitable for low speed flight. Two settings decrease camber... this is when the two flapperons move upwards.... and this is suitable for higher speed flight.

#AvGeek #Aviation #ElectricAircraft #Homebuilt #Glider #DIY #EAA #Technology #Wing #Aileron #Flap #Flaperon

TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

@KrajciTom@universeodon.com · 3 months ago

Adjusting the flaperons.

This video shows them operating as ailerons. I move the control stick side to side.

Note that at max deflection, the control surface moves above neutral position more than it moves below neutral position. This is the principle of differential ailerons. It helps reduce adverse yaw.

The first comment to this toot will be a video showing the motion of the flaperons as camber changing flaps.

#AvGeek #Aviation #ElectricAircraft #Homebuilt #Glider #DIY #EAA #Technology #Wing #Aileron #Flap #Flaperon

TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

@KrajciTom@universeodon.com · 3 months ago

The glider's flight controls need final rigging/adjustments.

First photo shows that the left and right spoilers are extended the same amount, which is the desired condition.

But we need to check and ensure that they also lock (into the over center position) identically.

Second photo shows the view of one of the spoiler drive arms, as seen through an inspection port. I have added black marks to show when the arm is in the over center position.

How do I adjust the action/throw of the spoilers to ensure they are synchronized? By adjusting the length of push-pull tubes, such as the one I'm pointing to in the third photo.

Now that the spoilers are adjusted, I need to do similar checks and adjustments of the flaperons.

#AvGeek #Aviation #ElectricAircraft #Homebuilt #Glider #DIY #EAA #Technology #Wing #Spoiler