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Old Mar 13, 2013, 06:49 PM
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Originally Posted by Chrizz View Post
Hi Builder Bob!

The prop does not especially seem too big in relation to the plane, it looks quite ok. It really depends on what you want to accomplish, but in this case, to me, it looks adequate (compared to i.e. some aerobatic planes, it is not that big at all). A more important question is, if it is the right prop for the chosen motor?
I think you'd like to resize the elevator, it is very small compared to the rest of the plane. In general, you'd want to have a very large tail surface, both horizontal and vertical, otherwise you might end up with a lack of stability.

Happy landings :-)
that's the recommended prop for the motor I ordered so I hope it works.

I already have remade the elevator, it was way to small!

I also colored the plane with a sharpie. would elevator/aileron or elevator/rudder control be better?
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Old Mar 13, 2013, 10:21 PM
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Denmark, Central Denmark Region, Silkeborg
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Hi builder bob!

If the prop is the recommended one for that motor, then it (hopefully) should be good, if not perfect! :-)

Don't hesitate to make the rudder quite big to, I could not tell its size from the previously posted picture.

The most common solution for a 3 channel setup is rudder/elevator/throttle, but the plane will require some dihedral build in the wing to get a suitable, stable flight.
Both setups will work, but it depends of the specific application.
In this case I would recommend RET (rudder/elevator/throttle) with some dihedral.

PS it might not be a bad idea to color each side of the plane differently (i.e. the wing, left/right), to better recognize its left from its right in the air.
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Last edited by Chrizz; Mar 13, 2013 at 10:26 PM.
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Old Mar 14, 2013, 04:59 PM
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Quote:
Originally Posted by Chrizz View Post
Hi builder bob!

If the prop is the recommended one for that motor, then it (hopefully) should be good, if not perfect! :-)

Don't hesitate to make the rudder quite big to, I could not tell its size from the previously posted picture.

The most common solution for a 3 channel setup is rudder/elevator/throttle, but the plane will require some dihedral build in the wing to get a suitable, stable flight.
Both setups will work, but it depends of the specific application.
In this case I would recommend RET (rudder/elevator/throttle) with some dihedral.

PS it might not be a bad idea to color each side of the plane differently (i.e. the wing, left/right), to better recognize its left from its right in the air.
here's a better view of the rudder and elevator. I haven't added any dehidral yet because I need to cut the piece of carbon fiber that's in the wing.

i'll try using rudder and elevator control I guess.

coloring each side of the plane diferently is a good idea but I've never had a problem with disorientation when flying any plane.
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Old Mar 19, 2013, 12:18 PM
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the parts are at the post office! I don't know if i'll be able to pick them up today though because the roads are bad.

edit: I've got to get them tomaro
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Old Mar 20, 2013, 08:45 PM
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got the parts! the motor and battery's allot bigger then I thought. the motor didn't come with a prop saver like it said it did!

I've got a problem; I already had ordered a 2s battery to try but that has a eflite umx connecter and the 3s I got has some other one and a balance lead. is their any way I could use both?
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Old Mar 21, 2013, 10:48 AM
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The thing I'm still puzzling over is why a 16" span model should need a battery and receiver that weigh more than 100 grams and why it would possibly need 200 grams of thrust? That isn't a model plane, it's a rocket about to rip its' wings off - so how much dihedral it has doesn't really matter, they won't be there long enough to make a difference.
I wouldn't use that weight of equipment in a model over twice that size. It's 3 times what my 18" span models actually weigh ready to fly. Unless you're a very good pilot I'd rate the models' life expectancy in seconds. It is, I take it, supposed to fly like a pylon racer?

Sorry if that sounds harsh, I'm just trying to figure out what is going on here and why nobody else queried a 16" model carrying over 4 ounces of gear. Those are utterly ridiculous figures. Those 10 gram outrunner motors will fly a gentle flying 30" model weighing around 6 ounces.
Remember, the heavier a model is (for a given size), the faster it has to fly just to stay in the air. The faster it flies, the harder it is to control and the more likely it is to crash. Being heavy to start with, the harder it hits the ground and the more damage it's likely to do.
If your model is intended to be easy to fly, rather than a projectile, I'd suggest you at least double its' size to use the gear you seem to have. You definitely don't need a thrust to weight ratio of 2:1. A 16" model weighing 8 ounces is a disaster waiting to happen. Give us more precise details (brand, specs, weight) of what gear you are using and maybe we can guide you towards a successful model. From your photo, I'd think you might be over estimating the weights. That receiver looks awfully similar to the Orange 410 and that weighs around 4 grams.
As a guide, this 18" model weighs 35 grams ready to fly.

Pete
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Old Mar 21, 2013, 08:28 PM
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I couldn't find any thing light so I just found a motor that I thought would barely be able to move it all. unless I read all the weights of the stuff wrong (which is entirely possible), just the electronics would be around 500 g which I thought was way to heavy for the motor. like I said in the beginning this is my first design and so I thought I the hole set up shouldn't way any more then twice the thrust produced by the motor. this also is only my second plane build (the first has around 3:1 thrust to weight). I can down size the battery to a 2s 120 mah battery if it's necessary.
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Old Mar 21, 2013, 09:03 PM
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As I said, I am trying to help, so let's start with a basic question. How well could you fly your 3:1 thrust/weight model? You're well into the realms of 3D power there and well beyond the requirements of a novice type model.

More out of curiosity, are you really trying to put 500 grams of equipment onto a 16" span model? That's almost the entire weight of some 48" models I've built.

Just going through your list, I can see that you aren't. At most your motor, receiver, 2x servos, ESC and battery come to 50 grams. So, that gives two obvious points. 1) you can't add up simple numbers, or 2) you're taking the piss.
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Old Mar 22, 2013, 05:33 AM
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Okay, it was late when I did my last post and I was tired and crotchety. When I saw that every link posted included the weight of the item it was like a red rag to a bull.

Anyway, we now know that your airborne components weigh a maximum of 2 ounces, not the 17 ounces you suspected. Although how anyone could mistake one for the other I've no idea. At least your model doesn't need to be too lightly built if you're to use the 200 grams (7.14 ounces) thrust your motor is capable of. Mind you, given the quoted current draw, your 180 mAh pack is good for around 3 minute flights only.

What are your actual goals with this model?

Now there's a worrying thought, a 16" span model, built from 9 mm EPP and carrying 17 ounces of gear. The mind boggles....

Pete
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Old Mar 22, 2013, 07:09 PM
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Originally Posted by PETERRAKE View Post
As I said, I am trying to help, so let's start with a basic question. How well could you fly your 3:1 thrust/weight model? You're well into the realms of 3D power there and well beyond the requirements of a novice type model.
i can fly my bipe that has the high power set up well (it's way easier to fly then my trainer), just haven't learned to do anything 3D. i know that there is no need for 3:1 thrust/weight but i thought that if i could get it to 1:1 and make a simple plane it might be as forgiving and easy to fly as my biplane.
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Originally Posted by PETERRAKE View Post
More out of curiosity, are you really trying to put 500 grams of equipment onto a 16" span model? That's almost the entire weight of some 48" models I've built.
i had decided to use 16" for the wingspan because that is a little larger then the horid little biplane that my brother had gotten and we were just going to swap over the parts. then the wires on the motor broke so i went through hobbyking looking at the weights of things and i thought i needed a plane with 200 g of thrust.
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Originally Posted by PETERRAKE View Post
Just going through your list, I can see that you aren't. At most your motor, receiver, 2x servos, ESC and battery come to 50 grams. So, that gives two obvious points. 1) you can't add up simple numbers, or 2) you're taking the piss.
i think that the reason why i thought that everything was so heavy was that i didn't realize that the weight that is listed by the product on hobbyking is the shipping weight...

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Originally Posted by PETERRAKE View Post
Okay, it was late when I did my last post and I was tired and crotchety. When I saw that every link posted included the weight of the item it was like a red rag to a bull.
it's fine, I've had so many people say what i'm doing is stupid it just seems funny now.
Quote:
Originally Posted by PETERRAKE View Post
Anyway, we now know that your airborne components weigh a maximum of 2 ounces, not the 17 ounces you suspected. Although how anyone could mistake one for the other I've no idea. At least your model doesn't need to b, e too lightly built if you're to use the 200 grams (7.14 ounces) thrust your motor is capable of. Mind you, given the quoted current draw, your 180 mAh pack is good for around 3 minute flights only.
i'm glad I won't need to build lightly, i'm bad that. it's too bad that we ordered that small of a battery, I did it because I thought everything was going to be to heavy

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What are your actual goals with this model?
easy to fly and not underpowered
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Now there's a worrying thought, a 16" span model, built from 9 mm EPP and carrying 17 ounces of gear. The mind boggles....

Pete
I can photocopy the plans I made to make it bigger. I sanded down most of the foam that I was using exept for the wing which I tried to put some air foil on
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Last edited by builder bob; Mar 29, 2013 at 10:06 AM.
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Old Mar 29, 2013, 09:58 PM
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doubled the size of the plans so now the wingspan would be about 32 inches, is that a good size?
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Old Mar 30, 2013, 07:55 AM
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Glad you bumped this, I've been meaning to get back to you.
I was going to suggest making it twice the size, increasing the dihedral and making all the tail surfaces bigger.
Stick with your 9 mm wing, sanded to section but try to use thinner stuff for the tail surfaces - 3 mm?
Ideally, the tailplane should be around 1/4 to 1/3 the area of the wing.

Pete
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Old Mar 30, 2013, 08:57 AM
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alrighty i'll do that. the elevator is already about 1/3 of the wingspan but i'll enlarge it. the rudder should be 1/4-1/3 of the wingspan or just the elevator? are my little servos powerful enough?
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Old Mar 30, 2013, 12:08 PM
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there's a problem with using 9mm foam to make the wing; I can't really put much of an airfoil on it. I was able to round the front and slope the back on the small wing but it had a flat spot in the middle. if i double the size of the wing to around 6 1/2 inches the flat spot would be huge and the wings wouldn't provide much of any lift. I don't think I have enough epp to rebuild my biplane and double up the foam in this plane's wing. how much extra weight would be added by using blue insulating foam (which I think I have)
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