You could well be right Jesse.
However, I have bought this wire many times and have always found that it is only in the 300ft reels that one gets a colour choice or indeed a decent choice of conductor styles. And those reels cost a huge amount of money, and no homebuilder will want to buy that much. The people who sell it by the metre sell just white, IME.
Peter wrote:
I don’t think normal aviation wire is Tefzel. It is irradiated PVC e.g. Raychem Type 55 is by far the most common
ETFE is Tefzel isn’t it, Tefzel being the Dupont tradename for ETFE? Might be wrong. Most wiring is MIL SPEC 27500 of 22759 and available from quite a lot different sources. Raychem’s Type 55 is one of them.
I do use different colours, which is slightly more expensive than using white. Different colours make future upgrade and troubleshooting far more easy. Same is true for wire marking, which I also use for the same reasons.
I don’t think normal aviation wire is Tefzel. It is irradiated PVC e.g. Raychem Type 55 is by far the most common.
You can get it in different colours but most people use only white because
IMHO the wire in that aircraft is not heat resistant, but may be the next grade up from plain old PVC which is +70C max.
Tefzel comes in lots of colors, red included.
And back to Peter’s mystery aircraft: all of the cabling is red – can it be fire-resistant? I only know of tefzel but that is usually white-coloured?
Not that fire-resistant cabling is a requirement for me, but if this installation is so exemplary than it definitely ought to have that.
Fair enough, but the idea of a firewall is to keep the fire on the outside, not to lock it on the inside. There is no right or wrong here. A Sonex with the ULPower engine crashed because he mounted the FADEC module on the engine side of the firewall without ensuring proper cooling. In my opinion as much as possible should be on the outside, and cooling issues should be handled there. For a Rotax with a heat exchanger, I don’t see what cooling issues there should be unless you for some reason force the exhaust air into the engine compartment.
No I don’t.
Jan_Olieslagers wrote:
But it IS queer to see those accessories on the business side of the firewall, in my craft they are on the much more protected – and less hot – cockpit side.
We don’t see what the top cowling look like. It may very well be a duct there guiding fresh air to that component. I doubt it is needed though, lots of air comes through the front opening of the cowling, and the engine doesn’t give off much heat being water cooled. It’s certainly higher than ambient, but not that much. It also depends how the heat exchanger is mounted.
You really do want to mount as much as possible on the business side, especially things that may eventually heat up.
tomjnx wrote:
If anything, long thin wires should dampen fast rising transients.
True, this is why long thin wires to the capacitor are useless (also for reducing rimple).
tomjnx wrote:
How do you know? Or is this conjecture? Switch mode power supplies usually generate quite some transients on their own, furthermore they typically have a huge input voltage range, and thus quite some headroom for transients and “dirt” coming their way from the outside…
True, sure it could be a conjecture. Have had lots of issues with several switch mode avionics products, same fault on several Rotax PM generator powered aircraft. I haven’t seen this fault on Lycoming / Continental powered aircraft, neither on Rotax aircraft with an external alternator. Oscilloscope view reveals output with lots of transients. at the bus. These don’t occure when switching from internal alternator to external alternator. Peter wrote:
Peter wrote:
It probably depends on where the capacitor is. If it is at the start of the long wire then you get a poor transient response.
This is why IMHO the capacitor is placed incorrect / incorrect wiring.
Peter wrote:
Also I am sure some voltage regulators have marginal stability. It’s a crude system – controlling the voltage by varying the field current
True, tough this system is as Jan also wrote with permanent magnets. The AC output is going in to the regulator, which rectifies and regulates. Quite poorly, there are lots of issues with this regulator.
Jan_Olieslagers wrote:
It might be a good idea to bypass it, though, with a parallel capacitor with good HF/transient handling, ceramic or so. Though I never heard of such a reommendation, it can never hurt.
That wouldn’t be much of help, due to the long thin wiring. Your basic idea of using multiple capacitors parallel is always a good idea.
