Anyone got tips on how to bulid a glider

[aloev]

i intend on DIYing my own glider...

first time doing it...

so need some help from those 'old gears' out there...

any help will be much apprecaited...

[Curare]

i intend on DIYing my own glider...

first time doing it...

so need some help from those 'old gears' out there...

any help will be much apprecaited...

Talk to the Guru of scratch building....Joe Yap

[Junwei]

introduce him to me oso can? haha.. i oso wanna noe more bout building frm scratch.. thanks man...

Junwei

[jon-AMIG]

Question here too.

Taper ratio. How much is enough & how much is too much? Also does flexing of the wing helps the glider to go the extra "mile"?

Thanks in advance

[Demented]

i heard the temasek poly guys doing a chuck glider competition...
r u guys joining?

[xwing]

Best glider competition?

[joe yap]

Taper ratio can be quite tricky to determine. Usually designers try to avoid excessive taper which can trigger early tip stall, due to the low Reynold's number on the tip. I'll say, most small gliders has the tip chord more than around 60% of the root chord, unless some kind of airfoil geometry or stall delay devices are incorporated at the tip. This is just a very rough guide.

The flexing of the wing does nothing to help the glider to achive the extra mile actually. Ideally, there should not be any flex which can reduce the flight controls effectiveness and wing efficiency. The main thing they want to achieve is the high aspect ratio wing which reduces induced drag. Of course, the side effects are structural flex as mentioned, and the lower critical angle of attack. That's why modern high performance gliders have to be flown carefully.

For our sport glider models, we try to stick to around 8:1 or 10:1 for aspect ratio and thin airfoils around 8-9% thickness. If you use too thick an airfoil, say around 14% onwards, low speed handling will suffer and the airflow above the upper wing skin tends to seperate even before reaching stall angle.

[jon-AMIG]

Ok..I understand that now. Thanks!

[Curare]

Taper ratio can be quite tricky to determine. Usually designers try to avoid excessive taper which can trigger early tip stall, due to the low Reynold's number on the tip. I'll say, most small gliders has the tip chord more than around 60% of the root chord, unless some kind of airfoil geometry or stall delay devices are incorporated at the tip. This is just a very rough guide.

The flexing of the wing does nothing to help the glider to achive the extra mile actually. Ideally, there should not be any flex which can reduce the flight controls effectiveness and wing efficiency. The main thing they want to achieve is the high aspect ratio wing which reduces induced drag. Of course, the side effects are structural flex as mentioned, and the lower critical angle of attack. That's why modern high performance gliders have to be flown carefully.

For our sport glider models, we try to stick to around 8:1 or 10:1 for aspect ratio and thin airfoils around 8-9% thickness. If you use too thick an airfoil, say around 14% onwards, low speed handling will suffer and the airflow above the upper wing skin tends to seperate even before reaching stall angle.

You the man..Joe. Figured that you would be the right person to ask about scratch building.

[jon-AMIG]

Ya..Im asking these question is because My team & I are joining the Hand-launch Glider Competition in sch.

So here's another question. How does the wing span of the glider affects the descend rate of the glider? Longer wing span = longer distance? Then also shorter chord = higher aspect ratio = better lift?

Thanks..

[joe yap]

For a given fixed wing area, increasing the aspect ratio increases the lift to drag coefficient, meaning it produces less drag for a given lift coefficient or vice versa.

However, due to the side effects like lower critical angle of attack and lower reynold's number, wing aspect ratio for small models should not be to high.

Since chuck gliders are not guided, the pitch stability must be more positive than a R/C glider.

[P4cm4n2000]

hi Jon...use lead weight to balance in front. Don't use plasticine cos it dries up or melts, and days before the competition trim runs out slidely.

most of my competition gliders back 20yrs ago at JFC uses 1/8" to 1/4" light balsa (choose the super light ones, usually whiter in color),
1/16" tail / rudder, 1/8"x1/4" spruce (top) glued to balsa fuselarge.

the dihedral of the wing also affects.... unfortunately all my plans no longer with me now...

you got to really try many times to see the decent rate by adjusting the nose leadweight forward or backward (i.e. CG) until you are happy with a slow decent.

I believe YFC have many chuck glider plans or do a search.

All the best bro!

[jon-AMIG]

Hi John! Im actually thinking of foam ribs & balsa spar because those are the materials I have now! Haha..

Here's another question: Is it possible to have constant thickness on taper wings? Then under-cambered wing gives better lift? But not that wise to use under-cambered wings on hand-launch glider(so its also called chuck gliders?).

Thanks!

[joe yap]

Maybe you'll like to let us know what's the size of the glider you are looking at.

[jon-AMIG]

Im thinking of a glider with 1metre span, mean chord approx 8cm & a T-tail. I have two pieces of 1metre by 3/8'' by 1/8" balsa strips. One for main spar, another for leading edge spar. What do you think?