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150 hp conversion for 2 place Grumman

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george.mueller(at)aurora.
Guest

Posted: Wed Jun 03, 2009 5:43 am Post subject: 150 hp conversion for 2 place Grumman

I am considering purchasing a two place Grumman with the 150/160 hp conversion.  What is the scoop on this conversion?  How fast will the airplane go?  What is the range with and without aux tanks?  I usually fly by myself or with one person, so this setup seems to be a way to get speed without a lot of cost but I am wondering what the trade-offs are with this airplane.   

 

 

George C. Mueller [quote][b]

JHOSLER(at)epri.com
Guest

Posted: Wed Jun 03, 2009 5:54 am Post subject: 150 hp conversion for 2 place Grumman

A friend of mine had one.  I would not recommend it.  Minimal range, gross weight is not increased so you have major weight restrictions AND weight and balance is way off- nose heavy  (very difficult to land).  

   

The plane flies beautifully with the original engine.  

   

John  

         

  

From: owner-teamgrumman-list-server(at)matronics.com [mailto:owner-teamgrumman-list-server(at)matronics.com] On Behalf Of george.mueller(at)aurora.org

 Sent: Wednesday, June 03, 2009 9:32 AM

 To: teamgrumman-list(at)matronics.com

 Subject: 150 hp conversion for 2 place Grumman  

  

   



 I am considering purchasing a two place Grumman with the 150/160 hp conversion.  What is the scoop on this conversion?  How fast will the airplane go?  What is the range with and without aux tanks?  I usually fly by myself or with one person, so this setup seems to be a way to get speed without a lot of cost but I am wondering what the trade-offs are with this airplane.   

 

 

 George C. Mueller    	  Quote: 	
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      [quote][b]

aa1bflyboy

Joined: 23 May 2008
Posts: 30

Posted: Wed Jun 03, 2009 6:22 am Post subject: 150 hp conversion for 2 place Grumman

George C go for it C the O320 is the engine the two place should have had all along (IMHO). You gain gross weight (depending on which STC you use). Not all of them do. If your CG is fwd you can install a Skytech LW starter and if you still are fwd CG relocate the battery to behind the baggage compartment. I used the AirModsNW STC and I get better than 1500 FPM climb flying alone with half tanks (16 gallons) I have the aux tanks in the wings. Even at GW I get better climb than the stock engine did when I flew alone with half tanks. Range is still more than 3 hours so my back and my bladder give out before I have too much air in those tanks to fly.

  

 The only thing I would do differently would have been to buy a two place already converted to the O320. So if anyone is thinking of buying a two place fly both before you buy a two place with the stock engine.

 

Steve Roberts 

AA1B - 641HY (at) ILG 

AYA Region 2 Director/Forum Admin 



We shall not cease from exploration. 

And at the end of all our exploring 

Will be to arrive were we started 

And know the place for the first time - T. S. Eliot

  

  To: teamgrumman-list(at)matronics.com

Subject: 150 hp conversion for 2 place Grumman

From: george.mueller(at)aurora.org

Date: Wed C 3 Jun 2009 08:32:22 -0500

I am considering purchasing a two place Grumman with the 150/160 hp conversion.  What is the scoop on this conversion?  How fast will the airplane go?  What is the range with and without aux tanks?  I usually fly by myself or with one person C so this setup seems to be a way to get speed without a lot of cost but I am wondering what the trade-offs are with this airplane.   

George C. Mueller [quote]

[b]

_________________
Steve Roberts

flyv35b(at)minetfiber.com
Guest

Posted: Wed Jun 03, 2009 6:56 am Post subject: 150 hp conversion for 2 place Grumman

George,

  

 The trade offs are range and useful load.  Speed  is all over the board depending on whether it is and AA-1 or AA-1A/B/C,   has wheel and gear leg fairings, the prop pitch and a 150 or 160 hp  engine.

  

 The biggest question is what STC was used for the  conversion as there are main STC's that I am aware of (Fletchair's, Air Mods NW  and Maynard Crosby).  The one Fletchair sells is the so-called Collier STC  and has a severe RPM restriction which would drastically reduce you top and even  the cruise speed.  The Air Mods NW STC only permits the O-320-A & E  series engines, which are only 150 hp but has no RPM reduction (2700 rpm  redline) and has a gross weight increase for takeoff only.  This is an  IMPORTANT consideration as the bigger engine and heavier prop will result in  less useful load.  Maynard's STC allows 160 hp versions of the O-320 (B  & D series) at full 2700 RPM, for takeoff and initial climb at  least.  

  

 There are some other considerations such as the AA-1C  has a larger tail which is more effective and makes flairing a little  easier.  It also came stock with an oil cooler and dynafocal engine mount  and is the only model that doesn't have any recurring AD Notes on the  airframe.  But all the O-320 conversions should have and will need an oil  cooler.  Some will have the battery located in the original location on the  firewall and others will be either in the baggage compartment or just behind it  (not very good for service, etc).  Quite a few will have an extra 10 gal.  of fuel or a very few have 20 gal extra.  Ken Blackman at Air Mods NW and  Gene Plazak at Dallas Metroplex Aviation can answer your questions about the aux  tanks.

  

 All these conversions will have a Sensenich 74DM6 or 7  prop, which can be reduced from 74 2 to 72.5 2 as I recall.  Prop pitches  seem to vary from about 60 2 to 64 2 with the 60 2 pitch being a climb prop and  used on slower planes without wheel and gear fairings and a 64 2 pitch being used  on a fast plane with full gear fairings.  

  

 Some info based on my AA-1C which has a 63 2 pitch prop  cut down from 74 2 diameter to 73 2:  My top speed is 170 mph with the engine  turning 2850 rpm down low (only flown like this long enough to stabilize and get  the data).  At 10,000 ft or higher the full throttle rpm is still at least  2700 rpm.  The plane has full wheel fairings with the brake cover, leg and  sump fairings from an AA-5A/B.  I think all these add about 10 mph or  more.  The plane needs another inch or so of prop pitch to take advantage  of the power and maybe increase cruise speed a little but it climbs great at  2500 rpm and 100 kts.  I've seen 1500 FPM by myself on a cool day!   I've also flown it out of a 5000 ft altitude grass strip (3500 ft long) at  full gross weight (1684 lb.) on a cool morning (40 F) and not had any  problem.  Useful load for takeoff is about 500 lb. so that leaves 368 lb  for people and baggage.  The CG (with the battery on the firewall) is at  the forward limit with no baggage and just the pilot but there is PLENTY of  elevator to flair and keep the nosewheel off the ground for a long time after  touchdown.  And I can put just about anything in the baggage it will hold  without exceeding the aft CG limits.  The other models have less CG range,  so for several reasons I think the AA-1C is the most desirable  model.

  

 A cruise speed at 8500 ft or higher is 155-160  mph if I push it to 2650-2700 rpm.  It is slightly faster than a Tiger and  will outclimb one unless the Tiger has only one person.  Fuel consumption  is between 7 and 8 gph up high, leaned out, depending on power setting.   Range is ABOUT 275 nm or possibly a bit more at reduced power  settings.  10 gal aux tanks would increase this to nearly 450 nm.   With  A fuel flow instrument (instantaneous and totalizer) is almost  mandatory for these planes to be able to safely get the most range out of them  as the fuel gauges bounce around a lot in turbulence and you can't rely on them  totally.  You need to keep track with a watch and based on experience with  fuel flow at different power settings to assure adequate reserves.  There  is no published data for these conversions and planes will vary a lot from one  to another.  You have to develop your own information.  The 22 gal  useable fuel capacity limit it's range and usefulness for a longer distance  cross country traveler and the 10 gal aux tanks will help this a lot, but most  likely not allow you to carry any baggage or maybe only one person with full  tanks.

  

 At any rate this is a good plane that performs far  better than the original and can be operated most anywhere with the extra power  it has to overcome the high induced drag from the short wings at takeoff  speeds.  Prices seem to vary from around $25K to $40K depending on  condition, engine time and avionics.

  

 Cliff  A&P/IA

  

  

 [quote]   ---

jeremyawilliamson(at)gmai
Guest

Posted: Wed Jun 03, 2009 8:12 am Post subject: 150 hp conversion for 2 place Grumman

John, 



The AA-1A with 160 hp conversion is a fine machine. They are not all fine machines, it just depends on who did the conversion. Simply don't assume that one conversion is as good as another.  Have a GOOD inspection done on it because unless you have significant experience with these aircraft, you WILL NOT all the squawks on your own. I have one that I purchased about 5 years after the conversion was done.  The range is about 2 hours with VFR reserves.  As with any plane, whether you make it to your destination non-stop is a function of how far you are going, which direction the wind blows.  It's also a function of how long you can sit on a wooden seat until your ass starts to hurt.  Personally, for me, in the AA-1A the range just so happens to coincide with time when my butt needs a break.

 

If you want to see some actual data, check out my most recent flights on flightaware.com... http://flightaware.com/live/flight/N9464L



The plane is nose-heavy, but not bad. Use a little trim. It's NOT hard to land!!  If you are close to St. Louis I'd be happy to show you what the plane can do.  

 

You mentioned trade-off's. ALL planes have trade-off's.  You want aux tanks on your 160hp AA-1A then you will probably be flying alone. Or maybe you don't depending on the weight of you, your passenger and your comfort with the performance of the aircraft. With aux tanks you can make the plane go 3 hrs instead of 2.

 

Bottom line is: you should inventory YOUR needs from the plane against what it is the plane can provide.  If a majority of your flights are less than 2 hrs and consist of you and 1 other person and bags, the AA1 could be for you. Even if your flights are longer than that, determine how critical it is to you to go non-stop.  Also, keep in mind that it's possible to throttle back and lean out the mixture and get the same performance as the original airplane.

 

Jeremy



On Wed, Jun 3, 2009 at 8:48 AM, Hosler, John <JHOSLER(at)epri.com (JHOSLER(at)epri.com)> wrote:

 	  Quote: 	
		                  

A friend of mine had one.  I would not recommend it.  Minimal range, gross weight is not increased so you have major weight restrictions AND weight and balance is way off- nose heavy  (very difficult to land).  

   

The plane flies beautifully with the original engine.  

   

John  

         

  

From: owner-teamgrumman-list-server(at)matronics.com (owner-teamgrumman-list-server(at)matronics.com) [mailto:owner-teamgrumman-list-server(at)matronics.com (owner-teamgrumman-list-server(at)matronics.com)] On Behalf Of george.mueller(at)aurora.org (george.mueller(at)aurora.org)

  Sent: Wednesday, June 03, 2009 9:32 AM

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)

 Subject: TeamGrumman-List: 150 hp conversion for 2 place Grumman  

  

   



 I am considering purchasing a two place Grumman with the 150/160 hp conversion.  What is the scoop on this conversion?  How fast will the airplane go?  What is the range with and without aux tanks?  I usually fly by myself or with one person, so this setup seems to be a way to get speed without a lot of cost but I am wondering what the trade-offs are with this airplane.   

 

 

 George C. Mueller    	  Quote: 	
		    http://www.matronics.com/Navigator?TeamGrumman-Listhttp://forums.matronics.com 	
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-- 

Jeremy 

  [quote][b]

flyv35b(at)minetfiber.com
Guest

Posted: Wed Jun 03, 2009 9:13 am Post subject: 150 hp conversion for 2 place Grumman

So here you have a totally different opinion!   Sounds like a bit of hearsay info here.

  

 BTW the range will NOT decrease if you slow down and  fly at the same speed as the original.  Gross weight IS increased on all  models (84 lb on the AA-1C) with Air Mods NW STC.  And that is more than  the empty weight increases.  I've already discussed the CG and landing  capability relative to the CG and elevator control.

  

 Cliff

 [quote]   ---

GrummanDude

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

Posted: Wed Jun 03, 2009 9:43 am Post subject: 150 hp conversion for 2 place Grumman

Cliff, do you ever take this plane to fly-ins?

--

_________________
Gary
AuCountry Aviation
Home of Team Grumman

v1rotate(at)verizon.net
Guest

Posted: Wed Jun 03, 2009 12:21 pm Post subject: 150 hp conversion for 2 place Grumman

George,

  

 Our AA1C/150hp is equipped with Ken  Blackman's STC and aux tanks providing the common 10 gallons of extra fuel  (32 total).  In spite of a few acknowledged limitations in payload, I  have never regretted purchasing and flying this airplane.  My wife and  I are admittedly not large people.  I'm about 160lb. and she's about  125 lb., so the weight of the occupants is important.  With this in mind,  flying solo with full fuel at takeoff, I can climb to 13,000 ft+ for a 2:45  endurance and a 330 n.m. range.  With my wife aboard, I  can takeoff at the legal limit of 1684 lb. with roughly 21 gallons of fuel  and 60 pounds stuff in the baggage area.  This limits endurance and range  to 1:45 and 210 n.m.  There is one caveat in the later scenario.  The  legal landing weight for the AA1C is still 1600 lb. even with the  approved takeoff weight increase.  That means that if you legally takeoff  at 1684 lb., you have to burn 84 lb. of fuel before you land.  That's  14 gallons, or about 1:30 in the air.  To avoid landing over the legal  weight you therefore have to fuel the airplane appropriately for the intended  length of the flight with two people aboard.  I mention this only because  it's what the limitations say, in case you are a stickler in this kind of  situation.  To elaborate a bit with a practical example, depending on the  empty weight of the airplane, you could load up with two average  people (say 170 lbs or more), put a moderate amount of baggage in the cargo  area, and be at or even over the maximum landing weight with no fuel in the  airplane.  The "balance" portion of weight and balance is also  important with the big engine STC.  The heavier engine and prop will move  the cg forward.  In my case, which may be the extreme, I also have a rare  form of aux fuel tanks which are situated ahead of the wing spar,  whereas I think the majority of the aux tank installations are behind the spar  which makes a lot more sense.  You won't see too many installations like  mine.  They are field approved tanks, not STC'd, an if there are a dozen of  them out there I'd be surprised.  So, with the more likely aft aux fuel  tanks, I would imagine that some of the forward cg concerns would be alleviated.  I suggest you do a few weight and balance computations on any prospective AA1X  with the big engine and make sure they fall within the approved cg range  for the types of flights you intend.

  

 As far as handling goes, I can't comment on  the "AA1X" with the big engine prior to the AA1C because the earlier models  have the smaller elevator.  With the larger elevator of the AA1C I  find no overly objectionable issues with landing, as some have intimated,  even with my 99.9% of the time forward cg condition.  Yes, there is a  slightly nose heavy feel, but it is not bothersome and you have plenty of trim  authority.  In general, any version of the AA1 series, perhaps especially  with the O-235 engine, is less forgiving if you get too slow, but fly  it by the numbers and you will have no trouble.  Also, the big engine will  give you a much wider margin for error in this regard.

  

  The 150 hp conversion does make the AA1 series much  more capable, but it may be necessary to more carefully consider who you are,  what you are comfortable with, and what your typical trips demand from an  airplane as compared to an AA5X.  It is worth the extra time to make this  determination because if an AA1X/150 meets your needs you will have a  plane that is a huge amount of fun to fly, not to mention one that will attract  quite a bit of attention from passers by.  It's a great way to strike up a  conversation when some curious person starts asking what kind of plane you  have.

  

 Bill Kelly

 AA1C 39065

 Lancaster, CA



  

  

 

I am considering purchasing a two place  Grumman with the 150/160 hp conversion.  What is the scoop on this  conversion?  How fast will the airplane go?  What is the range with  and without aux tanks?  I usually fly by myself or with one person, so this  setup seems to be a way to get speed without a lot of cost but I am wondering  what the trade-offs are with this airplane.   

George C. Mueller 

 [quote] 	  Quote: 	
		  



href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List

href="http://forums.matronics.com">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/c

	
[b]

flyv35b(at)minetfiber.com
Guest

Posted: Wed Jun 03, 2009 2:41 pm Post subject: 150 hp conversion for 2 place Grumman

Sometimes here in the NW.

---

aa1bflyboy

Joined: 23 May 2008
Posts: 30

Posted: Wed Jun 03, 2009 5:04 pm Post subject: 150 hp conversion for 2 place Grumman

Bill Kelly wrote"

 << In my case C which may be the extreme C I also have a rare form of aux fuel tanks which are situated ahead of the wing spar C whereas I think the majority of the aux tank installations are behind the spar which makes a lot more sense.  You won't see too many installations like mine.  They are field approved tanks C not STC'd C an if there are a dozen of them out there I'd be surprised. >>



 Bill I'm another one of that dozen or so with the fwd mounted aux tanks... Anyone else out there? 

 BTW C I relocated my battery to behind the baggage compartment.



 

Steve Roberts 

AA1B - 641HY (at) ILG 

AYA Region 2 Director/Forum Admin 



We shall not cease from exploration. 

And at the end of all our exploring 

Will be to arrive were we started 

And know the place for the first time - T. S. Eliot

   

  



  [quote][b]

_________________
Steve Roberts

v1rotate(at)verizon.net
Guest

Posted: Thu Jun 04, 2009 1:53 pm Post subject: 150 hp conversion for 2 place Grumman

Hi  Steve,

  

 So you have the tanks that were field  approved out of Hemet, CA?  Could I get your personal email  address?  I know I've seen it, but I don't keep everyone's  around.

  

 Bill Kelly

 v1rotate(at)verizon.net (v1rotate(at)verizon.net)

  

 

Bill I'm another one of that dozen or so with the fwd mounted aux  tanks... Anyone else out there? 

BTW, I relocated my battery to behind the  baggage compartment.

    [quote][b]

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