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AG5B Jaguar
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GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Sun May 02, 2010 1:06 pm Post subject: AG5B Jaguar

Bill Scott's STC limits rpm to 2650 rpm.  Same as limiting manifold pressure at sea level.   

 

  Ned, I talked to Ken yesterday about making a 10:1 -A4K.  A 10:1 -A4K would be limited to about 2550 rpm at sea level to make 180 hp.  Limit with rpm or MAP, it's the same result.  A none ported and polished 10:1 -A4K will make about 210 hp at 2700 rpm.  

  

 

  Ken would be interested in doing the development work if you're interested.  One of my customers is selling his plane, a 76 TIger with a mid-time engine, for $58,000.  If you buy the plane and get the engine modded by LyCon, I can get Bob on board for the flight tests.  Since you know what needs to be done, you could work with Bob and Ken and perhaps duplicate the testing done by Firewall Forward.  I'll take care of the paperwork that I can do and do the flight testing with Bob as the FAA rep.  Sounds like a great idea.  

  

 

  Gary

 

  

 

 

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Gary
AuCountry Aviation
Home of Team Grumman

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Sun May 02, 2010 3:42 pm Post subject: AG5B Jaguar

"Same as limiting manifold pressure" is true  only for a fixed pitch prop. We are talking about using a constant speed prop  right?

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flyv35b(at)minetfiber.com
Guest

Posted: Sun May 02, 2010 4:35 pm Post subject: AG5B Jaguar

Why?  Reducing either will decrease  horsepower.  A manifold pressure limitation would be better since you would  be able to have full power at altitude after the MP drops to the limit.  So  at altitude it would act as a larger more powerful engine.  Limiting RPM  would limit you all the way from the ground up.  But limiting RPM with the  governor setting is easier to control and less likely for the pilot to CHEAT  during takeoff and climb with a CS prop.

  

 Bill Scott limited RPM to 26r0 since that was the rpm  that resulted in a 5% increase in HP.  For the 180 hp that would amount to  whatever resulted in 189 hp.

  

 Cliff

 [quote]   ---

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Sun May 02, 2010 6:02 pm Post subject: AG5B Jaguar

The idea is to show the FAA that you are not exceeding the HP certification of the engine. So put in 10:1 pistons and limit to manifold psi that equals the previously FAA approved HP limit for the engine. This is the route Firewall Forward took and were succesful with in achieving FAA approval.

 LAike you say Cliff if you limit by RPM you will get less Thrust. Limit by MP pressure and you can still crank out the RPM up high.

This assumes a controllable pitch prop. AND most controllable pitch props are most efficient at less than 2700 RPM more like 2400 - 2500 As I understand it. So the idea is to get rated HP at the most efficient prop RPM  



Sent from my iPhone



On May 2, 2010, at 7:33 PM, "flyv35b" <flyv35b(at)minetfiber.com (flyv35b(at)minetfiber.com)> wrote:



[quote]  Why?  Reducing either will decrease  horsepower.  A manifold pressure limitation would be better since you would  be able to have full power at altitude after the MP drops to the limit.  So  at altitude it would act as a larger more powerful engine.  Limiting RPM  would limit you all the way from the ground up.  But limiting RPM with the  governor setting is easier to control and less likely for the pilot to CHEAT  during takeoff and climb with a CS prop.

  

 Bill Scott limited RPM to 26r0 since that was the rpm  that resulted in a 5% increase in HP.  For the 180 hp that would amount to  whatever resulted in 189 hp.

  

 Cliff

 [quote]   ---

GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Sun May 02, 2010 7:52 pm Post subject: AG5B Jaguar

no, I wasn't.  lots of folks out there with -A4K and no CS prop.



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Gary
AuCountry Aviation
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GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Sun May 02, 2010 7:59 pm Post subject: AG5B Jaguar

The Mooney has a CS prop.  There are a lot of things you can do with a CS prop that you can't with a fixed pitch.  Unless you are going to limit the 10:1 to planes that also purchase a $15,000 prop, the conversation makes no sense.  People out there just don't have that kind of money.  I can put a 10:1 engine together at top overhaul for $6,000.  That makes a hell of a lot more sense than trying to sell an MT prop at the same time.  

 

  Kevin opened the conversation when I talked about a derated 10:1 -A4K for Tigers.  How the conversation assumed a CS prop was included is beyond me.  

  

 

 

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Gary
AuCountry Aviation
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Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Sun May 02, 2010 8:11 pm Post subject: AG5B Jaguar

So why was it that you thought it was a  great idea?

 [quote]   ---

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Sun May 02, 2010 8:22 pm Post subject: AG5B Jaguar

Gary,

  In all your testing for the Jaguar  Cowling did you happen to get before and after manifold pressure data? If so,  for the same conditions, is the manifold pressure lower with the Jaguar  cowl than with  the factory cowl? Seems apparent that you have slowed the  airflow over the cylinders ie dropped the pressure on top of the  cylinders.....

  

 Ned



  

   [quote][b]

GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Mon May 03, 2010 1:56 pm Post subject: AG5B Jaguar

I have slowed the airflow down, Ned.  And, thanks to a fellow named Bernoulli, pressure goes up.  I got 1.5 to 2.5 inches more pressure drop across the cylinders than stock using half the inlet area.  All those years in fluid dynamics weren't wasted.

 

  

 

 

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Gary
AuCountry Aviation
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GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Mon May 03, 2010 4:48 pm Post subject: AG5B Jaguar

I'd be using your money.

 

  

 

 

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Gary
AuCountry Aviation
Home of Team Grumman

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Tue May 04, 2010 4:37 am Post subject: AG5B Jaguar

Without starting an argument about the oversimplification of trying to apply Bernoulili's principle to the airfow in your cowl, let me simply ask again,

Do you have before and after manifold pressure data comparing manifold pressure in the cylinder head with the factory cowl and your cowl?

As you know Pressure drop across the cylinders is not even close to answering this question

Ned 

Sent from my iPhone



On May 3, 2010, at 2:08 PM, teamgrumman(at)aol.com (teamgrumman(at)aol.com) wrote:



[quote]I have slowed the airflow down, Ned.  And, thanks to a fellow named Bernoulli, pressure goes up.  I got 1.5 to 2.5 inches more pressure drop across the cylinders than stock using half the inlet area.  All those years in fluid dynamics weren't wasted.

 

  

 

 

  --

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Tue May 04, 2010 5:26 am Post subject: AG5B Jaguar

Gary,

  

 What is the paint used on the inside of the  cowl?

 I need some more paint.

 It will need to be touched up after  the roughness and 'catches' have been smoothed out. 

  

 Thanks,

 Ned

   [quote][b]

flyv35b(at)minetfiber.com
Guest

Posted: Tue May 04, 2010 6:04 am Post subject: AG5B Jaguar

Are you talking about the AA-5B,  Ned?

  

 Gary's cowl (on his plane) uses the stock AA5B  induction system and I doubt that his cowling had any measurable effect on the  induction system manifold pressure.  If you get only 1" hg. MP drop at full  throttle on takeoff vs. atmospheric with the engine not running that is about  the best you can hope for and I think the Tiger system is pretty close to  this.  Increasing the pressure above the cylinders by 1" or 2" of H2O would  be unnoticeable on a MP gauge.

  

 Gary's real complaint has been with the efficiency, or  lack thereof, of the AG-5B induction system.  See his recent comment  below.

  

  • The first step is to fix (i.e., correct) the poorly designed carb air  inlet using as much hardware as is already there. The idea is to provide  something that is simple to install and regains the lost inch of pressure.

  

 Cliff



 [quote]   ---

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Tue May 04, 2010 6:34 am Post subject: AG5B Jaguar

Cliff,

  

 Yes I am asking what the manifold pressure on  the AA5B cowl is compared to the manifold pressure on the Jaguar  cowl.

  

 I'm not asking about the over cylinder  pressure, under cylinder pressure or the differential just the manifold  pressure. Either Gary has the data or he doesn't. I just want to  know if he has it and what it was. I'm not looking for an extrapolation  just if the manifold pressure was directly measured on both cowls.

  

 I need to eliminate all the variables so I can  determine why my plane is slower and hotter after the cowl installation than it  was before the cowl installation.

  

 Ned

 [quote]   ---

flyv35b(at)minetfiber.com
Guest

Posted: Tue May 04, 2010 7:10 am Post subject: AG5B Jaguar

I guess Gary will have to answer that.  I can't  imagine that MP would vary much at all.

  

 Cliff

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GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Tue May 04, 2010 9:09 am Post subject: AG5B Jaguar

Imron N0006

 

  

 

 

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Gary
AuCountry Aviation
Home of Team Grumman

GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Tue May 04, 2010 9:09 am Post subject: AG5B Jaguar

I didn't notice any appreciable difference in MAP between cowlings.

 

  

 

 

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Gary
AuCountry Aviation
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GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Tue May 04, 2010 9:47 am Post subject: AG5B Jaguar

Ned, take out the closeout you fabricated on the bottom of your cowling.  All of the flight tests were done with that open.  You'll notice a big difference in CHT.

 

  

 

 

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Gary
AuCountry Aviation
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GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Tue May 04, 2010 10:50 am Post subject: AG5B Jaguar

Ned,

  

 

  You changed the prop and the cowling at the same time.  And you're saying the cowling made the plane slower?  Are you serious?  I flew the plane, remember?  I also flew along side of you.  At 152 TAS, you're at least 12 knots faster than a stock AG5B.

  

 

  Ned, you got a hell-of-a-deal on that cowling.  $9000 installed.  It shouldn't cost more than $500 to get the outside painted to match.  I painted the inside for you to protect the fiberglass from getting oil soaked.  I exchange, you kept your old cowling and baffles which I usually keep to recover some of the 50 hours in labor I put into baffles, fitting, painting and installing the cowling.  I could sell cowlings all day long at $9000 installed if I wanted to go out of business.  As it is, I lost $4,500 on your installation alone.  

  

 

  Ned, I'm sorry you're not happy with the cowling.  You haven't been happy with the whole deal since we started.  I've gone out-of-my-way to accommodate you and the installation on your AG5B, including pissing-off my DER and DAR.  Nothing I've done seems to be good enough for you.  

  

 

  If you're not happy with the cowling, sell it to your buddy there in OK for $10,000.  Make a clean $1000 for your effort.  All the hard work in fitting and trimming is done.  You still have your original cowling, reinstall it.  His plane would only need (at the most) to have the engine mount shims adjusted to align the spinner.  I'm fairly certain he'd be happy with the cowling.

  

 

  

 

  Gary

  

 

  

  

 

 

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Gary
AuCountry Aviation
Home of Team Grumman

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Tue May 04, 2010 8:34 pm Post subject: AG5B Jaguar

Gary,

  

 I don't know where your coming  from at all. I really like your cowl. I liked following the journey you took to  get the cowl to where it is today. I appreciate your willingness to take on the  challenge of getting it installed on my Tiger.

  

 I don't understand why you are  unhappy. I don't understand your math. 

  

 You know full well that I paid  you $13,665.31 why state otherwise?  

 Don't you recall flying with me  at 152 ktas before the cowl was installed when I flew a couple hours to  help you deliver Martin's plane? Do you realize that you charged me for the  fuel burned in my plane on that trip? And for the two flights you made with  Krytie in my plane. Do you remember, on your first flight test in my plane, how  the engine burbled after take off over a gorge? And how you left me with a plane  that ran rough? And after I picked the plane up and made that 300nm trip to  Oxnard I found #2 AND #4 top spark plug wires only  inserted in the plugs and the hold downs were not screwed in not even one  thread.  Guess what, no more rough engine no more noisy radios after I  finished the plug wire install. Do you remember how you kept changing the deal  you made with me on the cowl? How you ask me how the alternator was wired  because you forgot how you took it apart?  Do you remember how you ask  me to get MT propeller to write a letter saying your cowl was okay with their  prop? And how you said you would not be able to sign off on the 337 and I would  have to have someone else sign off on it. How you spoke with my mechanic in  Oklahoma about this? Have you forgotten how you needed $5000 last January  in order to have a new cowl built for me but you ended up using the money on  baffles? Gee Gary I could go on but this should be enough for you to  get why I might be a little dissappointed in you.

  

 Again I'm happy with the cowl.  I suppose I just expected a different Gary. I'm just going to  consider that you were not at your best thru this.

  

 As for the speed increase we expected I  will continue working to get it. It has to be there. So I've cleaned the bugs  off the plane and double waxed it and been tweaking on it since I returned from  California last Thursday. Soon as I can I'll do more flight testing and I'm sure  we'll evently see the results from the cowl that we expected.

  

 ned  

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