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H.Zwakenberg

Instruments you really don't need

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Being a former sailplane pilot, it dawned on me that - with pusher aircraft - you don't need a slip indicator. Just do as sailplane pilots do: take a bit of tape and use it to attach a 2-3 inch long tuft on the centerline of your cockpit. That string tells you all you need to know - and quite a bit faster than that liquid damped slip indicator. Don't take wool, cotton or another natural fiber, as these cease to work when flying through a rain shower....

 

bye

Hans

 

[edit:] if you fly N-VFR or IFR, this might not be a good suggestion :)

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If you're flying a VFR day-only experimental, you need NO INSTRUMENTS except perhaps an ELT and a transponder:

 

http://rotarywiki.org/Minimum_Inst_Requirements.html

 

It took some doing to convince me, but 91.205 -- the FAR that lists the required instrumentation -- applies only to aircraft with standard airworthiness certificates. As experimentals, we are issued special airworthiness certificates. 91.205 doesn't apply to us. Now, the rules become applicable when equipping for night and IFR ops.

 

As for coordinated turns, doesn't the yarn, string, eventually scratch up the canopy glass?


Wayne Hicks

Cozy IV Plans #678

http://www.ez.org/pages/waynehicks

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another suggestion/question:

 

will it suffice to just monitor the hottest cylinder, or is there solid merit in fully instrumenting the engine?

 

bye

Hans

In theory this is correct, but which cylinder is the hottest?? The hottest Cyl can change due to power settingsand other factors, both normal and abnormal.

 

The real advantage (other than LOP operations) is that looking at each cylinder, you can many times diagnose ignition, injection, etc problems with a glance to the instrument. A full egt/cht unit can sometimes indicate pending problems before they become critical--- That is, of course if one looks at it and understands the meaning of what is being measured and what variations of the data means.

 

On the other hand, if you have no desire other than to lean to roughness and then enrich slightly, you don't need an EGT at all. CHT (on one cylinder, I think, is required, however


I Canardly contain myself!

Rich :D

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If you're flying a VFR day-only experimental, you need NO INSTRUMENTS except perhaps an ELT and a transponder:

 

http://rotarywiki.org/Minimum_Inst_Requirements.html

 

It took some doing to convince me, but 91.205 -- the FAR that lists the required instrumentation -- applies only to aircraft with standard airworthiness certificates. As experimentals, we are issued special airworthiness certificates. 91.205 doesn't apply to us. Now, the rules become applicable when equipping for night and IFR ops.

 

As for coordinated turns, doesn't the yarn, string, eventually scratch up the canopy glass?

 

In European countries, things are a bit more complicated than this.... Essentially, over here we need those instruments, that non-experimental planes would legally need to carry.

 

bye

Hans

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In theory this is correct, but which cylinder is the hottest?? The hottest Cyl can change due to power settingsand other factors, both normal and abnormal.

 

The real advantage (other than LOP operations) is that looking at each cylinder, you can many times diagnose ignition, injection, etc problems with a glance to the instrument. A full egt/cht unit can sometimes indicate pending problems before they become critical--- That is, of course if one looks at it and understands the meaning of what is being measured and what variations of the data means.

 

On the other hand, if you have no desire other than to lean to roughness and then enrich slightly, you don't need an EGT at all. CHT (on one cylinder, I think, is required, however

 

As far as I was informed - and in the context of my project, an IBIS pusher canard powered by a VW derivate - the #4 cylinder (starboard/aft) should be the hottest. Might be a simplification though, I don't know. Perhaps someone can enlighten me on this topic?

 

thanks,

Hans

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As far as I was informed - and in the context of my project, an IBIS pusher canard powered by a VW derivate - the #4 cylinder (starboard/aft) should be the hottest. Might be a simplification though, I don't know. Perhaps someone can enlighten me on this topic?

 

thanks,

Hans

Hans,

 

Although there is usually one EGT that usually runs hotter in a specific installation, EGT is merely an indirect measure of the combustion efficiency in a cylinder. This relates to the fuel air mixture and a bunch of other things effecting the burning of that mixture including swirrling of the mixture as it traverses the induction system and the ability of the gasolene not to condense out on the runners. If the assumption is made that the intake system is absolutely smooth without friction, and the carburetor or injection system mixes the entire mass of air with the same amount of vaporized or atomized air at all throttle settings (remember there is a butterfly in both the injected and carbureted engines) then the assumption that the hottest EGT would be on the same cylinder all of the time would be correct. It is not!

 

----Wait---- The hottest cylinder to which you refer is the hottest CHT, not EGT. That is a product of cooling air, essentially, not necessarily directly related to the combustion process. It is possible for the hottest EGT to be in the cylinder with the coolest CHT, although in reality probably not likely. The answer may be somewhere between.

 

The only way you can tell exactly what is going on-- If you want-- to is with multi probes.


I Canardly contain myself!

Rich :D

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