Thorp Air Command - T18.net

Supporting Owners, Builders and Pilots of the Thorp T-18 and its variants.
It is currently Sun Dec 22, 2024 8:27 am

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 70 posts ]  Go to page Previous  1, 2, 3, 4, 5  Next
Author Message
Rich Brazell
 Post subject: Re: RPM/EGT
PostPosted: Thu Feb 14, 2013 12:33 am 
Hero Member
Hero Member

Joined: Wed Oct 21, 2009 12:33 pm
Posts: 3108
Images: 64
Location: Jamul, CA (San Diego area)
Bill: I think you are correct in regard that the Marvel carb requires some type of "pressure " to the unit. My 1950 Ford 8-N tractor has the old reliable Marvel carb on it and gets it's fuel from a gravity fed tank above the carb... and there is some type of head pressure there ? Not sure how much , but has to be at least 1 psi ? ??? My 1950 Ford tractor NEVER gets above ground level so I am not worried about fuel feed . ;) My S-18 has a fuel pump for TO and landing . BOOM !

RB O0


Top
 Profile Personal album  
 
jrevens
 Post subject: Re: RPM/EGT
PostPosted: Thu Feb 14, 2013 2:44 am 
Sr. Member
Sr. Member
User avatar

Joined: Thu Oct 22, 2009 10:13 pm
Posts: 789
Location: USA
The vent line that most of us use, when pointed into the wind, does create a measurable amount of pressure. At cruise speeds in a Thorp, it can amount to something like 1/2 psi. That may not sound like much, but it can also be looked at as an increase in head pressure that would be created by having your fuel level about a foot higher than it is. These are very rough estimates based on my memory (known to be faulty). Looked at another way, you will have about the same pressure feeding the carb while flying when your fuel level is low as you would have when sitting on the ground with a full tank. I'm too lazy, but those of you so inclined could look up Bernoulli's equation & do the math. Fluid mechanics never was my favorite subject. If you do, tell me how far off I am.

Gravity flow works perfectly with a T-18, and that has been proven for 50 years with all size engines, but you need to give yourself every advantage, in my humble opinion, if you're smart.

_________________
John Evens
Arvada, Colorado

T-18 N71JE (sold)
Kitfox 7 SS N27JE


Top
 Profile  
 
Bill Williams
 Post subject: Re: RPM/EGT
PostPosted: Thu Feb 14, 2013 6:07 am 
My advantage is a fuel pump


Top
  
 
Rich Brazell
 Post subject: Re: RPM/EGT
PostPosted: Thu Feb 14, 2013 3:28 pm 
Hero Member
Hero Member

Joined: Wed Oct 21, 2009 12:33 pm
Posts: 3108
Images: 64
Location: Jamul, CA (San Diego area)
I had lunch with Tom Bernoulli yesterday and he said..."turn on your boost pump for take off and landing ." My advantage is also a boost pump .

RB O0


Top
 Profile Personal album  
 
david read
 Post subject: Re: RPM/EGT
PostPosted: Thu Feb 14, 2013 10:08 pm 
Sr. Member
Sr. Member

Joined: Tue Oct 20, 2009 9:21 pm
Posts: 228
Location: USA
John is right as usual. My research once after an argument shows that it takes a little over 200 knots to make 1 psi. That has to at least improve airflow. You can also use a similar pressure chart to calibrate your airspeed indicator.


Top
 Profile  
 
dan
 Post subject: Re: RPM/EGT
PostPosted: Thu Feb 14, 2013 10:47 pm 
Sr. Member
Sr. Member

Joined: Wed Oct 21, 2009 9:30 am
Posts: 898
Images: 0
Location: USA
Don't look to me like your memory is lacking at all John, 1/2 psi is good. One of the attributes of the Thorp is simplicity, this attracted me from the start, not only that but it's down right good looking. Dan


Top
 Profile  
 
Rich Brazell
 Post subject: Re: RPM/EGT
PostPosted: Thu Feb 14, 2013 11:11 pm 
Hero Member
Hero Member

Joined: Wed Oct 21, 2009 12:33 pm
Posts: 3108
Images: 64
Location: Jamul, CA (San Diego area)
Dan...you are simple and good looking , but I am NOT attracted to you !

RB O0


Top
 Profile Personal album  
 
jrevens
 Post subject: Re: RPM/EGT
PostPosted: Fri Feb 15, 2013 1:22 am 
Sr. Member
Sr. Member
User avatar

Joined: Thu Oct 22, 2009 10:13 pm
Posts: 789
Location: USA
Thanks, David & Dan. To you fuel pump guys... when I say give yourselves every advantage, I'm mostly referring to a great advantage when using a gravity-flow system in a T-18. Everybody knows that fuel pumps never fail, and because of that you would never need or want any additional pressure to help push fuel through all those check valves & multiple pumps (or whatever you guys use), even if it is simple & free. I believe in K.I.S.S., as I know John Thorp did. Then there are those who wear a belt AND suspenders. ;) All kidding aside, whatever gives you peace of mind is OK with me.

_________________
John Evens
Arvada, Colorado

T-18 N71JE (sold)
Kitfox 7 SS N27JE


Top
 Profile  
 
dan
 Post subject: Re: RPM/EGT
PostPosted: Fri Feb 15, 2013 8:15 am 
Sr. Member
Sr. Member

Joined: Wed Oct 21, 2009 9:30 am
Posts: 898
Images: 0
Location: USA
Aw Gee Rich, now ya hurt my feelins...................Ya onery Cuss....Dan


Top
 Profile  
 
Fraser MacPhee
 Post subject: Re: RPM/EGT
PostPosted: Wed Mar 06, 2013 10:11 am 
Sr. Member
Sr. Member

Joined: Wed Oct 21, 2009 8:57 am
Posts: 722
Images: 19
Location: USA
Here is the new vent scoop - will put a bug screen on it and test fly - will report any "mixture" changes.


Attachments:
VentScoop.JPG
VentScoop.JPG [ 1.87 MiB | Viewed 12615 times ]
Top
 Profile Personal album  
 
dan
 Post subject: Re: RPM/EGT
PostPosted: Wed Mar 06, 2013 8:04 pm 
Sr. Member
Sr. Member

Joined: Wed Oct 21, 2009 9:30 am
Posts: 898
Images: 0
Location: USA
That's interesting Frase...........Dan


Top
 Profile  
 
Rich Brazell
 Post subject: Re: RPM/EGT
PostPosted: Wed Mar 06, 2013 8:17 pm 
Hero Member
Hero Member

Joined: Wed Oct 21, 2009 12:33 pm
Posts: 3108
Images: 64
Location: Jamul, CA (San Diego area)
Like Dan said...very interesting ! :-* Looks like part of an air powered phone they used on WW II Battleships . ??? It will certainly push some air ! :o I am sure it will work just fine ! :P If in doubt you could always use it as an ice cream scoop ! :))

RB O0


Top
 Profile Personal album  
 
James Grahn
 Post subject: Re: RPM/EGT
PostPosted: Wed Mar 06, 2013 8:42 pm 
Hero Member
Hero Member

Joined: Sat Oct 24, 2009 7:16 pm
Posts: 1462
Images: 0
Location: USA
That's a lot of air. You are carberated right?
Cubes


Top
 Profile Personal album  
 
Rich Brazell
 Post subject: Re: RPM/EGT
PostPosted: Wed Mar 06, 2013 10:29 pm 
Hero Member
Hero Member

Joined: Wed Oct 21, 2009 12:33 pm
Posts: 3108
Images: 64
Location: Jamul, CA (San Diego area)
1. You may have to hook up ram air heat to the tube to prevent in flight icing . ;)
2. Go the the County Clerks Office and give the Girl a name . Bertha ? :o
3. Make a "Kilt" Ram air tube cover . 8)
4. Declare it as a dependant on your income tax . ::)

BADA BING , BADA BOOM !

Just funnin with ya Bro !

RB O0


Top
 Profile Personal album  
 
dan
 Post subject: Re: RPM/EGT
PostPosted: Wed Mar 06, 2013 10:54 pm 
Sr. Member
Sr. Member

Joined: Wed Oct 21, 2009 9:30 am
Posts: 898
Images: 0
Location: USA
Lets see what that little scoop does I'm kinda curious.........Dan


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 70 posts ]  Go to page Previous  1, 2, 3, 4, 5  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 15 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron

[ Time : 0.116s | 13 Queries | GZIP : On ]