X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 10 Jan 2006 21:28:13 -0500 Message-ID: X-Original-Return-Path: Received: from web34914.mail.mud.yahoo.com ([209.191.68.193] verified) by logan.com (CommuniGate Pro SMTP 5.0.6) with SMTP id 921059 for lml@lancaironline.net; Tue, 10 Jan 2006 17:35:35 -0500 Received-SPF: none receiver=logan.com; client-ip=209.191.68.193; envelope-from=n103md@yahoo.com Received: (qmail 52039 invoked by uid 60001); 10 Jan 2006 22:27:10 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=n8eL+wpGIw3qFapCfxgZLGNfopdwy36ZYQCmYM8AZwE5UjAhtrAqX792SeHE9YzF6ZlfUeNuDUn00IILIViVPPYEImVYHq5sxIe4sy3tHFZo7CBvV7kAuB/LEOZLNTCuvi9jvTPh4bP6clm11X+7wCD+d2hgHuzm08GtERH1LCA= ; X-Original-Message-ID: <20060110222710.52037.qmail@web34914.mail.mud.yahoo.com> Received: from [12.146.139.19] by web34914.mail.mud.yahoo.com via HTTP; Tue, 10 Jan 2006 14:27:10 PST X-Original-Date: Tue, 10 Jan 2006 14:27:10 -0800 (PST) From: bob mackey Subject: Re: [LML] To header tank or not....that is the question X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1182435091-1136932030=:47937" Content-Transfer-Encoding: 8bit --0-1182435091-1136932030=:47937 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Others have mentioned the pros and cons of the header tank. PRO: + more fuel + gravity feed to engine + can be used to adjust CG forward + sight gauge might be the only fuel level gauge you can trust + less unusable fuel CON: - can dump 10 gal of flaming death in your lap during a crash - crummy access to back of panel - more plumbing - CG can move aft during flight, diminishing pitch stability One other advantage to omitting the header tank... If the cover is removable, you will have excellent access to the back of the instrument panel. Some have made the header tank removable, but that is more work. BTW, my airplane is plumbed to feed from the header or both wings to the engine. I take off and land on the header. No gauges on the wings, so after climb, I pump from wings to refill the header, then run the engine off the wings until descent or the wings suck air. I switch back to the header for descent and landing. Mike Soh asks... > Will the standard fuel bays give me sufficient flight time. Depends.... the wings are pretty flat, with no sump to catch the last quart of fuel. I would estimate that there are at least a couple of gallons of unusable fuel in each wing when you consider manuevering flight for a difficult landing. How low are you willing to go using only the wings? Also due to the flat package, it is difficult to accurately gauge how much fuel is in the wings. Below ~5-6 gal, you can't see any fuel through the filler. Again, due to the flat package, the top gallon or two in the wing tanks can blown out through the vents by yawing or taxiing turns. Of the 11 gal in each wing, I would consider at most about 7-8 gal usable, if I didn't have a header to pump the last two gallons into. Also consider your flight missions and engine choice. My high-compression O-320 averages 6.6 gal/hr from engine start to shutdown. I usually cruise at 10-12K feet for long legs. If you fly low, fast, far, or in interesting weather, you probably want a bit more fuel on board. > Should I move the Battery and hydraulic pump to the front as John mention. For convenience, some builders have cut panels out of the seat backs, then installed the battery and hydraulics behind each seat. This looks like the best arrangement to me, if your CG will be acceptable there. The area can be boxed in from behind for a very clean installation. My next one will be built this way. > What are benefit of the extended wing tip. Less induced drag at high altitudes. If you don't have a turbocharger, and oxygen system, you probably won't gain much from long tips. If you DO have a turbo and oxygen, then you might gain quite a bit of range. ... IF Vne (in True Airspeed) is sufficiently high to make use of the speed up high. > Should make the wing tips interchangeable? If you want to race down low, and also fly long high missions, then maybe it makes sense to swap tips. > Does anyone have flown one that can give me the flight characteristics. Not me... > Can I install speed brake in the 360.Will it fit? If you have a constant speed prop, you won't need the speed brakes. I have a wood prop, O-320 on a 235 airframe. The lack of drag causes long landing rolls. Speed brakes won't help that nearly as much as a C/S prop. When flying formation with other LNC2s with C/S props, I have to drop the gear an inch or two before descents. Otherwise I overrun the formation even with the engine windmilling. -bob mackey 235 / O-320 flying 360 / Subaru ~50% --------------------------------- Yahoo! Photos Ring in the New Year with Photo Calendars. Add photos, events, holidays, whatever. --0-1182435091-1136932030=:47937 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: 8bit
Others have mentioned the pros and cons of the header tank.
PRO:
+ more fuel
+ gravity feed to engine
+ can be used to adjust CG forward
+ sight gauge might be the only fuel level gauge you can trust
+ less unusable fuel

CON:
- can dump 10 gal of flaming death in your lap during a crash
- crummy access to back of panel
- more plumbing
- CG can move aft during flight, diminishing pitch stability


One other advantage to omitting the header tank...
If the cover is removable, you will have excellent access to the
back of the instrument panel. Some have made the header tank
removable, but that is more work.

BTW, my airplane is plumbed to feed from the header or both wings to the engine. I take off and land on the header. No gauges on the wings, so after
climb, I pump from wings to refill the header, then run the engine off the wings
until descent or the wings suck air.  I switch back to the header for descent
and landing.


Mike Soh asks...
> Will the standard fuel bays give me sufficient flight time.

Depends.... the wings are pretty flat, with no sump to catch the last
quart of fuel. I would estimate that there are at least a couple of gallons
of unusable fuel in each wing when you consider manuevering flight
for a difficult landing. How low are you willing to go using only
the wings? Also due to the flat package, it is difficult to accurately
gauge how much fuel is in the wings. Below ~5-6 gal, you can't see
any fuel through the filler.

Again, due to the flat package, the top gallon or two in the wing tanks
can blown out through the vents by yawing or taxiing turns. Of the 11 gal
in each wing, I would consider at most about 7-8 gal usable, if I didn't have
a header to pump the last two gallons into.

Also consider your flight missions and engine choice.
My high-compression O-320 averages 6.6 gal/hr from engine
start to shutdown. I usually cruise at 10-12K feet for long legs.
If you fly low, fast, far, or in interesting weather, you probably
want a bit more fuel on board.


> Should I move the Battery and hydraulic pump to the front as John mention.

For convenience, some builders have cut panels out of the seat backs,
then installed the battery and hydraulics behind each seat. This looks like
the best arrangement to me, if your CG will be acceptable there. The area can
be boxed in from behind for a very clean installation. My next one will be built
this way.

> What are benefit of the extended wing tip.
Less induced drag at high altitudes. If you don't have a turbocharger,
and oxygen system, you probably won't gain much from long tips.
If you DO have a turbo and oxygen, then you might gain quite a
bit of range. ... IF Vne (in True Airspeed) is sufficiently high to make
use of the speed up high.

> Should make the wing tips interchangeable?
If you want to race down low, and also fly long high missions,
then maybe it makes sense to swap tips.

> Does anyone have flown one that can give me the flight characteristics.
Not me...

> Can I install speed brake in the 360.Will it fit?

If you have a constant speed prop, you won't need the speed brakes.
I have a wood prop, O-320 on a 235 airframe. The lack of drag
causes long landing rolls. Speed brakes won't help that nearly
as much as a C/S prop. When flying formation with other LNC2s
with C/S props, I have to drop the gear an inch or two before descents.
Otherwise I overrun the formation even with the engine windmilling.

 -bob mackey
 235 / O-320 flying
 360 / Subaru ~50%

Yahoo! Photos
Ring in the New Year with Photo Calendars. Add photos, events, holidays, whatever. --0-1182435091-1136932030=:47937--