Design

[someusername]

alright thanks. I may have found a little better place to test, but it is pretty cramped. On the note of turning off the AC, I doubt they could do that. I go to a school of roughly 1800 students so there is something going on in the gym almost every hour, and they prefer it cooler.

But all in all thank you very much for the feedback

[Toms_42]

Anyone have any adhesive tips? I'm building a plane tomorrow so I need to mix some adhesives. I have thin ca, brush on ca, and light epoxy which I plan on using for the dihedral joint. I also have a big can of weldwood contact cement, that could be diluted. I've heard of people diluting ambroid with acetone, but I haven't seen any in stores near me. Will the weldwood work the same way?

[jander14indoor]

See this document on the NSO website on glue, I wrote it a couple of years back for Wright Stuff, but it applies to all the building events where weight is important:
http://soinc.org/sites/default/files/up ... weight.pdf

For Wright Stuff you only need two, maybe three glues.
CA, I prefer the thin stuff because it wicks into joints better. It can be used for every wood joint on a WS plane and is plenty strong. There is no joint that requires the weight/strength of epoxy. Trick is to use very little of it, see link above for how. You MIGHT save a little weight using balsa cement like Testor's wood glue or whatever your favorite is, but they take longer to dry and special techniques like double gluing. CA will work and is much faster for those who have not yet developed the patience.

To attach the covering the 'traditional' solution is spray glue. Spray a VERY little on the frame where you want it to stick to the covering and drop the frame on the covering. Rub down, you are done. Weldwood contact cement (not the water based stuff, that will warp the balsa) will work. You'll want to thin it (a lot, with appropriate thinner), otherwise there is no way to brush it on other than WAY to thick. Then apply carefully to the wood surface you need to glue the covering to, a VERY little will do. Note, you don't have to glue every rib, just the outer frame and the dihedral joint. You can save a little glue/weight that way. DON'T get glue on other surfaces, will make handling difficult as well as add unneeded weight.

If you are making your own tissue tube, you'll need some balsa cement like Testor's or Ambroid that can be thinned, redissolved, and dry hard/non-sticky, Weldwood doesn't dry non-sticky so it can't really be used for this. If you reinforce critical joints (I tend to for the prop hanger and rear motor hook, not much else) you can lay on tissue in layers with Testors or Ambroid also.

Hope those are useful suggestions,
Jeff Anderson
Livonia, MI

[artysophia]

Hi! So I'm not sure if this is the appropriate place to pose this question but...
So I'm completely new at wright stuff and I built my first plane this week. It weighs exactly 8.0 grams (with added clay onto the center of gravity), the minimum weight. The wingspan is 40cm, and the wing cord is 8cm. I am used an Ikara prop w/ maximum diameter. However, I tested my plane a couple times, and it only flies for about 30 seconds. Again, I am completely new at this, so some advice and explanations would be greatly appreciated! Should I increase the wingspan to the maximum? Also, I may not be winding the rubber correctly...during my test flights, I have been using a 15:1 winder, and winding it approximately 15 times. Is that too little? I feel like if I wind any more the rubber will snap. I have also been double looping the rubber...is that inadvisable? I tried it once single looped, but I found that the propeller didn't spin fast enough so the plane kept falling down. Or maybe I didn't wind enough?

[chinesesushi]

Hi! So I'm not sure if this is the appropriate place to pose this question but...
So I'm completely new at wright stuff and I built my first plane this week. It weighs exactly 8.0 grams (with added clay onto the center of gravity), the minimum weight. The wingspan is 40cm, and the wing cord is 8cm. I am used an Ikara prop w/ maximum diameter. However, I tested my plane a couple times, and it only flies for about 30 seconds. Again, I am completely new at this, so some advice and explanations would be greatly appreciated! Should I increase the wingspan to the maximum? Also, I may not be winding the rubber correctly...during my test flights, I have been using a 15:1 winder, and winding it approximately 15 times. Is that too little? I feel like if I wind any more the rubber will snap. I have also been double looping the rubber...is that inadvisable? I tried it once single looped, but I found that the propeller didn't spin fast enough so the plane kept falling down. Or maybe I didn't wind enough?

you didn't wind enough. e.g. on my 1ST flight i wound the rubber about 400 times

[artysophia]

Do you suggest double looping the rubber or keeping it as it is (a single loop)? Also, when you mean 400 times, do you mean about 26 winds (x15 = approx. 400) because I am using a 15:1 winder?

[chinesesushi]

Do you suggest double looping the rubber or keeping it as it is (a single loop)? Also, when you mean 400 times, do you mean about 26 winds (x15 = approx. 400) because I am using a 15:1 winder?

I'm not an expert at this event (just started this year XD and never done flying events before) but I suppose it depends on the kind of rubber you're using/plane. Yes about 30 winds on the 15:1 winder. I suggest you PM jander14indoor or maybe wait for him to post here because he probably will He has a lot of experience with planes I think.

[jander14indoor]

Check back up this string and the other topics in this forum for some of your answers with explanations, but...

Absolutely, yes, you should be building to max span and chord. Less 1-2 mm to prevent getting second tiered because the ES ruler is different than yours...

Rubber, no where near enough winds. Winning flights will have more like 1200 turns, not 400, not 225. That's why you need to double up. Not enough torque with so few winds. To wind that many turns you'll need to lube your motors, again, look around this forum for why and how. If you aren't breaking motors fairly regularly, you aren't winding hard enough. Remember, this is a duration event, turns are fuel, why fly with a qtr tank (less, because the first turns store much less energy per turn than the ones near breaking).

But, need more info. The important thing about your motor is its width. You MIGHT double up if you only have very thin rubber. Example. Most of these planes will be flying on rubber between 0.080 inch and 0.105 inch wide (that's intentionally over wide range, I'd expect most to be towards the lower half of that range). If you only have some 0.045 rubber on hand, you might need to double up to get an effective width of 0.090 wide rubber. Why you'd have such small rubber I don' know unless you strip your own to width and that was just what you had left...

Oh, and what rubber are you using? Hopefully TAN Sport or TAN Super Sport. Office rubber bands just will not cut it.

Another Oh, how much rubber are you using? Again, you are allowed 2 gm, using a 1 gm motor, even if fully wound, is flying with half a tank of gas.

Regards,

Jeff Anderson
Livonia, MI

[artysophia]

1200 turns with rubber double looped? Alright, I guess I'll need to buy myself some lubricant.

The rubber I have is .093 Tan Super Sport. I am using about 1.9-2 grams. I have been doubling up my rubber (it is hard to do, but manageable). When I do not double up, my rubber is much longer than the distance between motor and rear hooks, so it cannot unwind all the way. Should I set the hooks farther apart or...?

[jander14indoor]

Sorry, not clear, 1200 is a single loop of 0.093 or so rubber. A double loop would never take that many turns and would overpower the plane if wound close to max. Just to make sure when I talk single loop that means there is one loop of rubber resulting in two individual strands running front to back. There is a way to have a single strand front to back, but not particularly useful for WS. Double loop means four strands front to back.

Hook length vs rubber length, just not important as long as you don't get TOO short. Loose hanging rubber is the norm for an unwound motor. Those first few wind (or last few unwind) turns will not provide any meaningful torque however you set the hook to hook length. And by few I mean 50 to 100 or so. Just use 12-14 inches hook to hook on these things and don't sweat it. I've flown some classes where the rules required about a 6-8 inch hook to hook for a 20 inch loop of rubber. Biggest problem with hanging rubber is it falling off or changing the CG unexpectedly.

Suggestion to understand torque vs turns, make up some short test motors and wind them with a torque meter taking data every few turns. Wind the first motor to breaking. Plot it. Wind the next identical motor to just short of breaking and then unwind continuing to take data. Plot it. You'll see why I'm saying the first turns are useless in powering the plane and why you MUST wind to near breaking. Reason and more details discussed previously, dig in the WS archives.

And yes you'll need some sort of lube to hit the turns you need to be competitive. But nothing hard to get.
- I use Armor All (or Son of a Gun) vinyl protectant, the original general purpose stuff, last time I looked there are a lot of specialized formulations. Works fine, I'm on my second bottle after 15 years. And the only reason I bought a new bottle was the old one was just NASTY smelling after 10 years in my flight box. One good spritz and that motor is good for many winds.
- Some folks use the silicone oil from RC car shocks. Also stays on.
- Haven't checked availability lately but there was a free flight supplier who sold a variety of amusingly named rubber lubes, things like Snake Snot, Mongoose Mucus, etc that was basically silicone oil.
- Old school was a mix of glycerin, soap and what not. Works, but not as good as silicone oil and must be reapplied.
- Whatever you do, DON'T use anything petroleum based, will ruin your motor like NOW.

Besides lubricant, you'll need to stretch wind to get those turns. Do some digging through the WS archives for more info on that.

Regards,
Jeff Anderson
Livonia, MI