The Plane Newsletter

A publication of Chapter 1111 Experimental Aircraft Association

February 2005 - February 2005 - February 2005 - February 2005 - February 2005 - February 2005 - February 2005


TECH COUNSELOR REPORT FOR FEBRUARY 2005

KEEP THE FIRE WHERE IT BELONGS: Part 3 (Exhaust)

In the past two months, I covered some precautions about the electrical system and fuel sytem installation. This month, I will discuss the exhaust system.

EXHAUST

Exhaust systems must be installed to safely carry the exhaust and associated heat away from the aircraft, and to conduct as little heat as possible to the airframe and nearby components. An engine under load generates enough heat to cause the exhaust system to glow cherry red.  If you have an EGT, you know the temperature exceeds over 1000 degrees F.  How fast would the roast cook if the kitchen oven could go over 1000 degrees?

Some engine installations create so much heat under the cowl, that the designers put a shield around the fuel pump and run a cold air duct off the pressure side of the cowl. Look at a Piper Cherokee and you will find this. The late Tony Binglis recommended that fuel pumps get the benefit of cold air to offset the heat created by the exhaust sytem. The concern is not about fire, but vapor lock by boiling off the fuel in the pump.

Tight fitting fiberglass or composite cowls need protection from the radiant heat of the exhaust sytem. An exhaust too close to the cowl needs to have an insulation barrier. There are products in the aircraft catalogs just for this purpose. Metal cowls can handle more heat, but the paint will suffer if the pipes are too close.

Some exhaust systems with long stacks need added support bracing or the engine vibration can fatigue the pipe and cause it to break.  Pay close attention to how the exhaust sytem designer shows the pipe supports. The supports usually have to be off the engine, so as the engine moves with the power pulses, the exhaust pipes follow with it.  

I have seen installations where the exhaust pipe has been supported off the motor mount, but this may actually induce failure.  As the engine moves in its mounts, the exhaust is forced to remain still with the motor mount. Sort of like bending a paper clip back and forth a tiny bit, but it all adds up.

Assume the engine is operating at 2400 RPM and the frequency of vibration is the same.  The math says 2400 x 60 minutes / hour =  144,000 bending cycles per hour.  Some systems have flex and slip joints to allow for motion, so there can be exceptions to how the supports are installed.

 

As part of the walk around before flight, it is a good idea to grab the pipe (cold of course) and check it for motion. In some installations, some motion is normal, but if the pipe seems to have excessive play or comes off in your hand, it is time to look further before flying.

 

I have had a personal, frightening experience of an in flight exhaust system failure, but that is another story for another time.


Plane Thoughts

This is a neat web site from the EAA Hotline that offers a builders construction log.  It will track work on various components or systems, and total  the  cost and time.  http://www.expercraft.com/


Builder Updates

 

Hot News!:

               

SAM AND SANDI ARCHER'S 180 HP MURPHY ELITE
 FIRST FLIGHT BY SAM,  DEC. 28, 2004



Calendar of events

EXECUTIVE BOARD MEETING AT KELSO FBO, 6 P.M. THURSDAY FEBRUARY 3, 2005

Next Club Meeting: Thursday February 3rd, 7:00 pm at the Kelso FBO

 

Program:

DON'T MISS THIS!  HEAR FIRST PERSON THE EXPERIENCES OF A NAVY TEST PILOT.
Our guest speaker will be  Mr. Robert (Skip) Leuschner USN retired. Mr. Leuschner soloed in 1959 and  flew actively as a test pilot and carrier pilot until 1975 when he went on to study nuclear propulsion. After 1975 he became a " boat driver" . 


Announcement

Keith Crimmin of the FAA will be at Kelso
Flight the evening of Wednesday Feb. 16 at 6:30 for a safety seminar.  This qualifies as the ground portion of the FAA Wings Program.  There is room for about 25 in the class room.  If you are interested, please
send an email to flykelso@pacifier.com so we've an idea of
how many people to expect.


Prospective ProjectorProposal

Whether noticed or not, a projector has been used in our chapter for the last few years to display presentations to the masses with great success.  Said projector has been a loaner from one of the members and it is time to find another source.  We have the opportunity to obtain a very nice projector at no cost to the chapter.  This proposal will explain the details of the EAA1111 projector, the raffle, and answer questions raised at the last meeting.

LCD and DLP projectors are the next step in projecting images from almost any media source onto the wall.  These projectors are different from overhead projectors or slide projectors in that they can accept input from computers, VCR's, and even digital cameras (if you remember the speech at our last annual dinner, a digital camera was plugged directly into the projector).  The technology behind these projectors has been on the same fast track as computers in the last few years.  Just a few years ago, these projectors were as large as a suitcase and cost five to ten thousand dollars making them available only to businesses and the very wealthy.  Recently, the projectors have become MUCH smaller and MUCH less expensive making them more appealing to the layman.  Projectors are showing up more and more in residential settings as the center piece of a theater style audio visual system, projecting a video image up to twenty feet across.

The raffle is simple.  Buy two projectors, give one away to the raffle winner.  Depending on the projector, the cost for each is eight to nine hundred dollars.  At the time of this writing, Costco was selling the Sharp XR-1S for $899.  Paul later called and told me he can get a 'Infocus' brand projector at their corporate prices of about $799.  If we were to sell a mere 100 tickets at $20 each (or 200 tickets at $10), we would have enough money for two projectors and a second cash prize of two to four hundred dollars (depending on the price of the projector).  A selling point of the tickets is simply a 1 in 50 chance of winning at least $200 (or $400) cash.  I am confident I could sell at least ten tickets.  If we were to split up the tickets among the chapter, I feel selling this would be simple.

Some questions raised at the last meeting when this idea was first presented:
What is the difference between a slide projector, overhead projector, this projector?
All of the above project an image onto a wall.  Slide projectors are limited to film slides as an input media, overhead projectors are limited to some transparent film with an image on it.  DLP/LCD projectors can have practically any electronic image input one would normally find on A/V equipment (s-video, component, digital video input, etc).


What tools are required?
No tools are required to use this equipment.  If one were to use the projector as a home theater, a ceiling mount is always preferable, although not required.


What will drive the projector?
DLP/LCD projectors can have practically any electronic image input one would normally find on A/V equipment (s-video, component, digital video input, etc).


How long before the bulb needs to be replaced?
All projectors use a high intensity bulb to project the image.  All bulbs have a life span.  The life span of most DLP/LCD projectors is around 3000 hours.  The Sharp model listed above has a lower intensity setting which is supposed to increase its lifespan to 4000 hours.  The major drawback to DLP/LCD projectors is the cost of the bulb which can run from one to three hundred dollars.  I am not sure of the specific price


What is the sweet spot for a ticket price?
$10, $20... not sure.  Any thoughts?


If we decide to do this, I will print some very nice looking raffle tickets explaining the prize to the potential winner.  We could coordinate the drawing with our annual fly-in which could also boost participation and 'buzz' in the fly-in.

Definitely a luxury, but one that is possible if we want to see it happen.

Please contact Eric Hoppe with any questions.

 


Officers and Committee Chairpersons

President & Tech Counselor Charlie Rosenzweig 577-6407 searose@kalama.com
V. President Paul Brown
Treasurer Fernando Cuglievan 636-5165  flcugl@kalama.com
Secretary & Newsletter Editor Jerry Sorrell 263-1532 jsorrell@worldaccessnet.com
Tech. Counselor Jay Tabor 425-6278 jtabor@scattercreek.com
Member at Large Steve Steinhoff 749-5298 flyrv@adelphia.net
Historian Terry Creamer 556-1670 terry@ados.com
Webmaster Bob Taylor 576-3806 bobtaylor15@comcast.net
Young Eagles Coordinator Sam and Sandi Archer 425-7777 sas@toledotel.com
Fly Out Director