planecrazy101

I posted this question in the radios forum, but haven't gotten a response. Maybe someone here can help.

I'm in the process of scratch building a Diamond Dust. I had planned to use aluminum arrow shafts for the spars, two for the leading edges, and two for spanwise spars. In this plane, the most practical way to install the antenna is through a looped pushrod tube inside of the plane. BUT.... will that cause interference? Thanks for the help.

FlooredCOBRA

maybe try using fiberglass or carbon spars in stead. I would be afraid the aluminum spars would kink in a hard turn or doing a 90' out of a dive and fold the wings.

Cactus.

My Feedback: (1)

don't loop the aerial, please dont loopt it, run it up a fin and let it dangle.
Ali spars should be fine, but where you get ali arrow shafts, you also get carbon ones... THEN YOU MUST NOT HAVE THE AEIAL INSIDE THE PLANE

pdxpaul

My Feedback: (1)

I used an aluminum arrow shaft as the main rear spar in my scratch built dust. However, it only went to the middle ribs, with a carbon insert out to the tips. The inserts almost touch in the middle. If not for the overlap, I think there would be too much flex in the aluminum shaft I found.

Unfortunately, that dust was yanked out of the sky by a two inch tree branch. Jett 50 at full throttle. The Jett hit the branch flush. Broke both the Jett and the branch. The only survivor was that aluminum/fiber spar. Go figure.

Portland has a kite shop that has a large stock of carbon fiber; solid and cored, different lengths, diameters, and wall thicknesses. You may want to look for a kite shop, as opposed to an archery shop, for the shafts.

Paul

planecrazy101

Thanks, guys. I knew I could depend on the speed freaks. The story is that a couple years ago, I built a DD kit. The first flight was okay, but tumbled and broke a fin on landing. Second flight, on the second lap around, it seemed like I just lost control. Either I didn't know what I was doing, or the solid chrome bottom caused interference. Well, now I'm into scratch building, or from plans, and I remembered that I had those DD plans. I wanted to build it VERY cheap since it's time on Earth may be limited. My wife picked up some crossbow bolts the other day for .75 each. They're pretty stiff, but short. I've joined two of them with a 8-32 screw into the head inserts, and it's more solid than I expected. Oh well, to cut it short, I'll cut some ribs as soon as I can find some suitable ply. One other incentive is that I live 2 1/2 hours from any hobby shops, and I hate to pay shipping for just a few parts. THERE. Now you know where I'm coming from. Hope to have it done soon and will post results. Any other sugggestions will be much appreciated. Later

P.S. have you had bad luck with the looped aerial Phillybaby?

sydclement

My Feedback: (1)

Planecrazy;
Jeff spent lots of time getting all the bugs out of
the DD and it looks like you may be trying to put
some of them back.
Better stay with the latest plans.

Syd

planecrazy101

Yeah, guess you're right. I'll email you my address so you can send me that $140. (Gettin two just in case, you don't mind right?). Come on. I bought a kit for the first one. I'd really like to build one cheaper to learn to fly. I promise I'll buy another kit when I'm ready to move up to that Jett 50. Thanks, and I'll be lookin for that cash.

Cactus.

My Feedback: (1)

aerials work best in two axis, ie about hale way you want a 90 degree corner. we cant do that in most cases, but looping it is asking for trouble, when you get LE on the aerial is flat and hidden behind the ali or carbon LE and you can loose signal. I've seen this happen with a loop Dust as he passed it glitched every time. with mine running up the fin and hanging out the back it has a few angels for the wave to hit and i dont get any glitches at any angle. i know lots of guys will say the loops fine but for me its a no no. i hate having the aerial inside a plane, and yes the crome bottom probably killed your plane

planecrazy101

Thanks, I will run it across the top and over a fin. This is a prototype anyway, to see how the structure holds up.

Is carbon fiber just as conductive as aluminum? If so, my arrow shafts may work fine, as long as they don't fold up.

Cactus.

My Feedback: (1)

Carbon fibre is a very good conductor, in fact i've seen many RC cars smoking from the batts shorting.
A good reason also not use use CF rods when fishing near powerlines or chance of storms
Why does the conductivity matter in this case?

planecrazy101

Well I was thinking that anything metal or conductive could act as a shield and cause interference. That's why i had the question about the alum. spars. I've seen a few times that it's not a good idea to run the antenna along next to a metal pushrod.

FlooredCOBRA

I used the loop on both my Dusts and had not had any problems yet. (knock on wood)

I think the plastic tube it is in keeps it sealed fairly well keeping the antenna from touching the carbon rods.

Cactus.

My Feedback: (1)

ahhhh you made it sound like a good thing in that last text. yes, keep it far away from the carbon and ali.
Tho that loop pic just shows me again why i hate it, good idea for keeping the aerial save tho. IF i did it, i'd run the loop as an triangle type oval right to a wing tip and back up towards the engine, aiming forthat 90 degree bend, but the aerial is still only in one axis

Rudeboy

Any conductive material can cause interference in reception.

Watch out with carbon...it can get very tricky to get good reception when there's a lot of carbon in a airplane...ask me how I know.

Always try to route your antenna in such a way that it can't get hidden behind some carbon or metal piece in the airplane. Also, don't run your antenna close to other conductors in the airplane...not even servo wires.

I don't see the problem with looping your antenna (if it is only 1 big loop that is...). Just make sure the entire loop isn't in the same plane, give it some ups and downs...

Them chome films really do contain metal most if the times, so watch out for them!

planecrazy101

Thanks for all the great info! Wish i had known all of this before my DD. It was beautiful. Cherry red, black down the middle and fins, and chrome rays each side of the black. The entire bottom was chrome Ultracote. I wanted it to flash in the sun, and it did for sure. Looked like a strobe light in a vertical roll. It got a litlle far out and I lost control in a shallow dive. Can you say YARD DART?