Re: [Paparazzi-devel] Tiny on larger glow/gas aircraft

[Paparazzi Pcb]

Daniel ,

I use IR Sensors on one of our large planes without any problems with a 
Desert Aircraft 150cc petrol
onboard without any problems , i also have used it on a smaller aircraft 
fitted with a 120 Glow , and again not had any problems , we fitted the IR 
Sensors ( fma ) on the top rear deck , below or should i say inside a clear 
dome .

any large aircraft should have seperate batterys and never rely on one 
battery to supply all power
we have seperate batterys for the rc reciever , paparazzi classic with gps & 
servo power , this is simple to do , lift out the positive servo pin at the 
servo connectors and route to one common point for all or even if in one 
case we had we seperated different servos across two batterys making sure 
each flying surface pair had one on each battery , this in case of failure 
of a single battery would give us one flying surface still working , so in 
principle we would still have control of the aircraft . and then connect the 
negative supply in common with the others , or use a few Y Leads can be 
modified to do this very easily , if your concerned over load spreading you 
can always fit to the y leads a diode in series in the positive wire IN4007 
in this case is fine , although try to keep connectors to a minimum , treat 
every connector as a potential hazard or trouble point , tie the connector 
together with a peice of string slotted between the wires stops them sliding 
apart , it's a lot cheaper than these plastic clips and less weight to

also a major problem to avoid is Interference , the servo wires and 
extentions available don't cut it
to help in this strip the wires down the joins and then plat them , doing 
the same with extentions too
we tend to make all our own extentions from heavier silicon wire which is 
much more flexable , last thing you need in a large model is current drop on 
a servo , this can give a number of problems from jitter , slow moving or 
even intermittent use

having a seperate battery for the rc reciever also again give a bit of 
redundancy in case of any problem
also using seperate batterys allows you to match the battery capacity to 
it's job , so in some cases smaller capacity batterys can be fitted , and a 
larger one for the servo's , where the capacity is needed , just about 
everything else is ticking over at a lower rate ,

this is normal practice for Large scale Aircraft and is a requirement , laid 
down by governing bodies
their is a lot of scope for improvements with a little thought

but dont forget the major do's , keep the airframe light !
and do your homework over wing loading ,

Dave

----- Original Message ----- 
From: "Daniel Kauter" <address@hidden>
To: <address@hidden>
Sent: Friday, February 08, 2008 1:44 AM
Subject: [Paparazzi-devel] Tiny on larger glow/gas aircraft


> Hi everyone,
>
> Has anyone tried using paparazzi with gas or glow engined planes, and if 
> so, was it a success? If not, could anyone speculate on whether it would?
>
> My concerns with it relate to the IR sensors:
>
> 1. Would the hot exhaust (which contains oils and residues) significantly 
> affect the angle measurements? There is likely to be hot exhaust behind, 
> and to one side of the aircraft, and possibly even below. The best 
> strategy I can see to mitigate this is to mount the x,y sensor high on the 
> tail.
>
> 2. Would the hot engine at the front of the plane affect the angle 
> measurements significantly? Hopefully the fuselage will shield most of the 
> engine from the IR sensors fov, but probably not completely.
>
> 3. Would hot oil and exhaust damage the IR sensors? Being on the outside 
> of the aircraft, I imagine it would be hard to ensure they are safe from 
> this.
>
> My only other concern is with regard to larger aircraft. Obviously the 5V 
> supply won't be capable of supplying 5 or 6 large servos, so I am planning 
> to supply them from a 6.0V NiCd. Does anyone know if the servos will have 
> a problem detecting their 5V PWM signals from the Tiny when their supply 
> voltage is higher?
>
> Thanks in advance to those who respond. Your input may save me a lot of 
> time pursueing something that might not work!
>
> Also, thanks to everyone who has helped create paparazzi. My team and I 
> enjoyed using it to build our MAV last year. I'm hoping we can continue 
> using it this year with a larger aircraft for this:
>
> http://www.uavoutbackchallenge.com.au/
>
> Maybe paparazzi can get another title under its belt!
>
> Cheers,
>
> Dan
>
>
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