FASST Users... Question for You

[wlfk]

Originally Posted by Santini

I fly with a group of guys w Logos so I have seen a bunch of crashes. I would have reservations about attaching the antenna to the boom. One crash comes to mind where the boom was completely sheered off, Ive also seen booms pretzelized. Would hate to see the rx ruined.

That's a very good point. But your receiver aerials are perhaps a bit close to the carbon fiber tail struts to work optimally. It's only the silvery bit at the end that's actually the antenna and this part should ideally be kept clear of anything conductive in order to keep its tuning correct.

Still probably better than "Nko15 I use the bobby watts style. Right next to each other. straight ahead."

I can't find any pictures of Bobby Watts' receiver, but... I can see why someone might do something slightly suboptimally because it saved a lot of effort. But why specifically aim to build a poor setup? Do you miss out threadlock on a matter of principle?

NKO - do you actually understand the reason for having two antennae, and how did you perform your range check?

[Nko15]

Originally Posted by wlfk

Still probably better than "Nko15 I use the bobby watts style. Right next to each other. straight ahead."

I can't find any pictures of Bobby Watts' receiver, but... I can see why someone might do something slightly suboptimally because it saved a lot of effort. But why specifically aim to build a poor setup? Do you miss out threadlock on a matter of principle?

NKO - do you actually understand the reason for having two antennae, and how did you perform your range check?

It really doesnt matter if you put them side by side. saw it on bobby watts his (both electric and nitro) Whiplash. The dual antennas are used for diversity, wich creates miles and miles of range. but them on the bobby watts style, and you still have about a mile range.. and really, i havent met anyone that flies an rc heli further than 3, maybe 400 meters.. The range check mode in pdm(power down mode) on my 7c still had about 150 meters of range. thats with about 1/10 the transmitting power.
Just a style of doing things.

Bobby's whiplash, few months ago:
http://www.rcheli resource.com/sneak...ghted-at-expo/
(remove the blank between rcheli/resource)

[wlfk]

Originally Posted by Nko15

It really doesnt matter if you put them side by side. saw it on bobby watts his (both electric and nitro) Whiplash. The dual antennas are used for diversity, wich creates miles and miles of range. but them on the bobby watts style, and you still have about a mile range.. and really, i havent met anyone that flies an rc heli further than 3, maybe 400 meters.. The range check mode in pdm(power down mode) on my 7c still had about 150 meters of range. thats with about 1/10 the transmitting power.
Just a style of doing things.

Well, according to your range check you should only have about 2.2x 150 metres of range - 330 metres so according to your own estimation, you should be able to fly out of signal. That's because radio power falls off as the cube of distance from the transmitter. 2.2^3 > 10.

But that's slightly aside the point. Antenna diversity isn't there to increase range*, but to ensure that the signal isn't blocked either by orientation issues (the range of a vertical transmitter to a horizontal aerial is much reduced relative to a vertical transmitter to a vertical aerial) or to reduce the chances of a single antenna being blocked by part of the helicopter.

With the older, lower frequency transmitters the radio waves were better able to travel round objects than the newer gigahertz transmitters. If you put a single antenna on the far side of a carbon fiber frame, range can be reduced very substantially.

What you really need to do is to perform a range check in a range of possible orientations, including the worst case scenario. This would be with the helicopter facing you so that the antennae are masked by the battery, motor and electronics, with the transmitter aerial pointing directly towards the helicopter and with the receiver antennae oriented directly towards/away from the helicopter. I suspect that the ground will bounce signals towards the helicopter, so your range on the ground will be slightly more than your range in the air. But I may be wrong on this.

Bobby's whiplash, few months ago:
http://www.rcheli resource.com/sneak-peek-new-heli-sighted-at-expo/
(remove the blank between rcheli/resource)

'You just encounter our 404 error page'

*Arguably this is just another way of saying that antenna diversity is there to increase range... because at short range these things are less of an issue. However, looking at the problem from a perspective of orientation and shielding is better in terms of actually understanding the reason for it. Also, two independent antennae and radio receivers with exactly the same setup aren't going to have a longer range than a single one so it's wrong to think that antenna diversity will ever increase maximum range.

[Nko15]

well,It works for me and alot of buddies.. and honestly, i cant care how others think of it.....

About the link, read... i said to remove the blank between rcheli and resource.

[wlfk]

I did change the link - it wouldn't have gotten as far as saying that ************** couldn't find the page if I hadn't gotten the domain name correct...

Aha... The link is truncated on my screen, but when I tried to reply to your email it showed me the complete link in one of the replies and now it works. I don't know what you see on your screen, but helifreak had inserted lots of dots in the original address.

http://www.rcheli resource.com/sneak...ghted-at-expo/

versus

http://www.rcheli resource.com/sneak-peek-new-heli-sighted-at-expo/

Bobby Watts may know lots about helicopter design, but if it was him who installed the electronics... I have to say, that's a spectacularly dumb way of fastening the receiver antennae. Almost as bad as you can theoretically get. I suppose if they'd taped them inside the frame it may have been worse.

Let me put it another way. Flying is all about reliability. If you have a 1/1000 chance of something going wrong, sooner or later it will bite. Which is why we use threadlock then do preflight checks anyway, to make certain that nothing's worked loose. And why we sometimes get the heeby-jeebies and replace blades that look OK after a crash. Or maybe you don't? Then there are dozens of ways for helicopters to fail. Bolts can work themselves loose despite threadlock, or they can snap. Batteries can open-circuit. Wires can chafe and short against carbon frames. Never had any of these things happen to me more than once... if at all, but they all bring down helicopters on a regular basis.

Anyway, it wouldn't have cost whoever set up that helicopter a thing to have at least put the antennae on either side of the frames, so I repeat... Why wouldn't you. And if you search for 'FASST' and 'lockout' you will find reports. It's good... excellent... but not bombproof.

[spektrex]

Originally Posted by Santini

I fly with a group of guys w Logos so I have seen a bunch of crashes. I would have reservations about attaching the antenna to the boom. One crash comes to mind where the boom was completely sheered off, Ive also seen booms pretzelized. Would hate to see the rx ruined.

Please note that in my solution the small pieces of fuel tube are shrinkwrapped to the servo horn, this leaves plenty of room for the antenna wires to move freely, they slide in and out with no effort, so in case of a tail boom accident the antenna wires simply slide out of the tube with zero damage. The thing I like is the guaranteed 90 degrees angle and the wires are not within very close range of any heli part, they are forced to hang completely free in the air left and right of the boom.