As you know, there is a natural metal front edge on most non-military jet engine intakes(Hyperlink). What is a good technique for getting this to look good?
http://boeing.com/companyoffices/gallery/images/commercial/767400-03.html
I get to view these a lot through the passenger windows …
Try dull aluminum paint, or gloss aluminum paint with the gloss rubbed down.
I haven’t tried the other types of metalizer finishes, hopefully someone who has can enlighten us both.
Regards,
Bruce
Try stainless steel buffing metalizer. I use it quite a bit, and it works pretty well. You can control the metallic sheen by how much you buff it.
If you’re feeling like spending lots of time to get it right, you could go pick up some adhesive-backed aluminum foil from your local hobby shop and do the engine inlets that way.
Nothing looks more like real aluminum than real aluminum!
So correct me if I’m wrong - but those silver edges to the leading edges of the wings, vertical tail, horiz. stab. and the engine inlets are all used for de-icing right? I’ve been told that hot bypass air from the engines is ducted through passages in these areas to super heat them and kleep ice from forming. Does any A&P mechanic out there know more?
They certainly aren’t using the pneumatic boots of old at any rate…
The metal leading edges usually seem to have a clear coat in real life. Either that or they don’t stain easily. I’d go with titanium or magnesium (ModelMaster metalizer), covered with a light coat of Future. ALclad II should work even better, but I haven’t used that yet. Somehow the metal looks darker on the real planes than bare aluminum foil, so that’s why I’d go with a slightly darker shade. Just my [2c].
You won’t find a clear-coat on those edges. They are an aluminum alloy.
Uilleann is correct. They are part of the aircraft’s pneumatic anti-ice system. However, it isn’t bypass air that’s used, as bypass air is MUCH cooler than compressor-core air. You’ll typically find that the hot air is taken (or bled) from somewhere in the high-pressure compressor section of the engine… From there it is routed through several command valves (ON/OFF valves) and pressure regulators to several tubes in the leading edges and intakes. The tubes are often called “piccolo tubes,” as they have holes in them to uniformly distribute the hot bleed air onto the inner surface of the leading edges and cowling. The temperature of the bleed air by the time it gets to the anti-ice surfaces is typically between 110 degrees F (43 C) and 300 degrees F (148 C). For reference, aluminum alloy melting points are between 865 and 1,240 degrees F, depending upon what metal the aluminum is alloyed with.
Several other interesting things to note is that only SOME aircraft have anti-icing on their tail surfaces. This has to do with the empennage airfoil’s uniformity and relative narrowness compared to the wings. Also, on many aircraft, you’ll find that there’s a speed above which wing anti-icing is not needed, except in special situations. This is due to frictional heating. A third interesting thing to note is that because of the anti-ice system’s use of high pressure air from the turbine stage of the engines, it significantly affects the performance of the engine. Often, if wing and cowl anti-ice is required during takeoff, rather hefty weight restrictions are imposed on the aircraft.
Probably way more of an explanation than anyone really wanted, but there you have it!
I can think of only one modern-day jetliner that uses inflated rubber boots. That would be the Dornier 328 Jet. Of course, this is a derivative of the turbo-prop version, so that might explain it.
Most turboprop airliners these days (yes they’re still around) still use good-old inflatables on their leading edges. These are strictly for de-icing (shedding ice after it has formed) rather than anti-iciing (keeping the ice from forming in the first place). The “pool toys” (as we used to refer to them) still work great when used properly!
That metalic leading edge is also found on old navy jets. It was dark gray metallic in color and was a special paint that didn’t degrade due to airodynamic friction at high speeds. The navy had always been real sticklers for looks. I once asked a Blue Angels pilot why they didn’t wear G-suits, and he replied “Because they mess up the crease in our flight suits.” There is a very practical reason they don’t wear G-suits, but it has nothing to do with creases. But that getting WAY off the original question.
Just an aside.
Where else could you get answers to a question like that except here in the Forum from experts. Thanks for the lesson Captain.
Richard
You’re quite welcome!
Modern jet aircraft leading edges are left uncoated because paint and those fancy clear coatings (sprayed on or adhesive tape) get eroded by air friction and just peel away. De-icing of an engine intake lip is not practiced as ice breaking off would FOD the engine. Anti-icing of an intake lip on the other hand creates a weight penalty and reduces the efficiency of the engine. Engines themselves will have anti-icing capabilities using hot compressor gases in the inlet vanes. There may be exception, but they are few.
Interesting stuff folks: still living and learning[:D]. Thanks for the explanations. Didn’t bore me for a second[;)].
Deleted on account of my own stupidity!
Captain I think you get something wrong here. Im an aircraft mechanic and I have worked on Boeing 737’s, Fokker 50’s, Canadair Regional jets, Challenger 604 and I now work on F-16s. All of them take the air from the compressor section and no air form the turbine section.
The air from the compressor section is used to De-ice / anti-ice and cabin pressurization. You cannot use post.burn air to pressurice the cabin, it would kill the passengers. Also the air from the compressor is used to cool the turbine inlet guide vanes. Compressor air from the 13th stage is usualy about 350-400 degress F, but the turbine inlet vanes is in an airstream thats about 2500 degrees F.
As recently as today we ran a couple of tests on the F-16 airconditioning system, and I can asure you the compressor is hot enough. [:)]
Edit: I see you deleted your answer Captain. Don’t worry I have been a trained aircraft mechanic for some years now and I still gets things mixed up from time to time. Then I just grap my school books and gets things straightened out again, we all make mistakes.
Monrad,
Yeah, thanks for that correction. I really feel a bit daft about now.
14th stage COMPRESSOR is what it says in all my notes. Guess I should have reviewed them a little more carefully before shooting my mouth off. In fact I thought what I was typing sounded a bit funny, and in my head I over-diagramed the engine stages.
I’m a MUCH better pilot than I am a mechanic anyways!
Thanks again for the correction. I’ll review everything else I wrote in order to ensure that I’m only partially full of crap! [:D]
Captain !! read my edit !! [:D][:)]
Your second post is to the best of my knowledge 100% correct.
Heh…we must have crossed posts there somehow!
Yeah, just because I’ve got an Airline Transport Pilot certificate doesn’t make me infallable! Again, I appreciate the good catch you made. Thanks for being so tactful in your correction of my post! You could easily have said, “THIS GUY IS A MORON!!!”
This is how we learn, for sure! Today I learned to check my facts before I let hot air escape from my gob!
I also learned to check my facts the hard way. And yet I still get things wrong from time to time because Im to confident.
And I don’t call other poeple morons, I don’t like to be called a moron myself.
Nice office you have there, what kind of aircraft is it??
It’s a Canadair Regional Jet. As I type this, I’m on an overnight in Medford, Oregon. I start work again today at 1400, and I finish up back here in Medford again after 6 hours of flying time today. Tomorrow, I’ll be in Bismarck, ND after flying from Medford to Denver and Denver to Bismarck. Easy day. I’ll be done with this trip on Sunday, just in time to commute home to barbecue and watch fireworks for the 4th of July!