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

From: Paparazzi Pcb
Subject: Re: [Paparazzi-devel] Tiny on larger glow/gas aircraft
Date: Fri, 8 Feb 2008 08:11:30 -0000

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 ,


----- 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:

Maybe paparazzi can get another title under its belt!



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