---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Sun 03/31/13: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:02 AM - Re: Re: N28697: Jaguar cowling (923TE) 2. 11:17 AM - Re: Re: N28697: Jaguar cowling (Gary L Vogt) 3. 11:41 AM - Re: Re: N28697: Jaguar cowling (Gary L Vogt) 4. 11:43 AM - Re: Re: N28697: Jaguar cowling (Gary L Vogt) 5. 12:18 PM - AA1B Jaguar cowling mockup (Gary L Vogt) 6. 07:21 PM - Speed Mod - Engine Down Thrust Angle (923TE) 7. 08:52 PM - Re: Speed Mod - Engine Down Thrust Angle (Gary L Vogt) 8. 11:41 PM - Re: Speed Mod - Engine Down Thrust Angle (923TE) 9. 11:53 PM - Speed Mod - Engine Down Thrust Angle (923TE) ________________________________ Message 1 _____________________________________ Time: 08:02:58 AM PST US From: 923TE <923te@att.net> Subject: Re: TeamGrumman-List: Re: N28697: Jaguar cowling Hi Gary and Bob, This looks like a discussion between the two of you. I haven't seen any of the emails posted to teamgrumman until this last one where my name is mentioned. Maybe this last post wasn't meant for the list? I'm only responding to the two of you. I really don't want to hash this all out again in public. My issues with your work, Gary, were primarily that you forgot to do what I ask about aligning the engine to the original factory cowl. As I look back on it, I think perhaps you didn't align my engine to the factory cowl because you didn't believe that was valid. We chased that a bit and I got some engine alignment data from the factory and forwarded that to you. Whether that was helpful or valid or not is another subject. Back to my Jaguar cowl. You had the Jag cowl aligned with the engine quite well. After I got home, I discovered that the pilot side upper mount nut had no bolt threads showing through and tightened it to factory specs. This moved the engine up and left quite a bit so that the cowl was now out of alignment. However, now my Tiger flew straight and level with all trim tabs neutral. This is how it flew prior to the upper left engine mount bolt being "loose." This fact along with the factory telling me that proper engine alignment is determined by aligning the engine with the factory cowl confirms in my mind that my engine is in the designed alignment. I did replace the Jag with the factory cowl and the engine is now aligned with the factory cowl. Another issue with the Jag cowl was that the bottom corners did not match my fuselage. Also, the spinner flange on the cowl was sticking out about 3/8" more than the MT spinner and the gap between the spinner and cowl was about 3/4". These things led me to look into refitting the Jag cowl. When I tried to align the cowl the right side was now not long enough. It was past the firewall flange screw holes. These are the reasons I extended the Jag cowl basically back to its pre-trimmed state and started over with installing it. The fact that my factory cowl was still quite "new" may be why the factory engine alignment method still works on my plane while you have found it doesn't work on the older 1970's planes. Or at least its inconsistent? I don't know. Maybe the engine mounts move with time and the cowl stretches? The factory told me that the lower cowl is drilled in a jig and that they are all the same when coming out of that jig. The cowl is then mounted and the engine alignment is compared to the cowl. If the engine is out of alignment specs then it is shimmed until it matches the cowl. They usually use the same number of shims but sometimes have to use more. It would be interesting to mount the Jag into the factory jig, drill the holes and see how well it aligns..... That's my summary. Yes, I'm probably more demanding than some and in my case it would have been much easier to have re-started with new parts but I didn't want to spend that much more for those new parts. The major hurdle at the time Gary installed the Jag was getting the STC approved on my AG5B. That was a big one and Gary did a great job of getting it approved so quickly. Hope this helps, Best Regards, Ned On Mar 31, 2013, at 1:01 AM, Gary L Vogt wrote: During the initial cowling fabrication, I made the assumption that each engine mount required one shim between the engine and the bushing. I installed a mockup engine on new Lord mounts on a 78 Tiger, N28840, using one shim on each mount. I laid up the new cowling using this as a starting point. When I installed the first cowling, actually a fiberglass 'splash,' on N119ST, it fit well using the same 'one shim per mount.' When I installed the second prototype, the first one flown, on N119ST, it also fit well with just one shim per mount. I installed the splash on John Bunker's Traveler. It didn't have any shims. It fit well. The first complete cowling was installed on N28747. 747 required 2 shims on each top mount. Each of the first 5 cowlings was installed on each plane using a trial and error method like that in the installation instructions. a lot of work. It was at this point that I started asking for feedback regarding the number of shims on Tigers. I also asked for the distance between the firewall and the back of the aft spinner bulkhead. The answers I got were varied and inconsistent. Ned wanted his cowling pre-fitted so he didn't have to wait very long. At that time, I had a wingless Tiger, N29348, in a neighboring hangar. To save time, I installed the cowling from N28747 onto 348. N28348 required 2 thick shims on the left and one thick plus one thin shim on the right in order for the cowling from N28747 to fit properly. After the new Jaguar cowling was completely fitted to N28348, I fit the lower cowling of the new Jaguar cowling to N28747 just to check. It fit fine. That cowling was installed on Ned's plane. Ned didn't like the fact that his engine needed shims to fit the cowling since he thought his original AG5B cowling was perfect and it fit well. Fast forward. I built a mockup for the Jaguar cowling using an AA1B, Cheetah engine mount, and the same mockup engine used in the original Jaguar cowling fabrication. I fit my cowling to the AA1B mockup and it required one thin shim on the upper right. I measured the thrust angle at .3 degrees down on the left side (no shim side) and .5 down on the right side. I then took the cowling from N28747 and installed it on N28697. It required 2 thick shims on the right and 2 thick plus one thin shim on the left. When done, the engine was .6 degrees down on the left and .4 degrees down on the right. The question that has been posed is: How well did the original cowling fit on N28697? 697 came to me with one shim on each mount. The engine was 1 degree up WRT the fuselage waterline. (thrust angle was not the same for each side.). The cowling fit OK. The engine looked like it was up just a bit, but not bad. Most people, let's just say 'no one' except me, would ever notice. So, why all the fuss? If the original cowling fit with the engine as is, what's the big deal with where the engine is? When I look at a plane, I see all sorts of poor fitting parts. Most, if not all, of the cowlings don't fit worth a damn. With 3/4 inches (or more) between the spinner bulkhead and the cowling, it can be off a lot and still look acceptable. Most people don't care. I'm an obsessive compulsive so it does matter to me. The space between the rear spinner bulkhead and Jaguar cowling is just 3/16 inches. The side-to-side location is less than 1/16 inches. The gap around the openings and cowling halves is less than .065 inches. Since my installation requirements are likely more stringent than most, I'm not selling anymore cowlings that aren't pre-fitted to a known installation. It'll cost more, but it will save the installer a lot of headaches. Gary Sent from my iPad On Mar 30, 2013, at 12:18 AM, Bob Steward wrote: > What I am asking is: Did the engine line up with HIS cowling? Or was your reference to "right place", saying that it did not match his cowl, and that once you re-aligned the engine, your cowl also lined up with it? > If you mean that the engine needs to be aligned differently for your cowl, how can those of us that do not have your plane handy to test fit a completed cowl, figure out the "right place", before starting to test fit an untrimmed cowl? > I can measure the thrust angle of 1/2 degree down with my digital level. Not sure about the offset to the (right) side. Could probably measure from firewall to some points on the engine, if I knew what those measurements were. > > Given only the information in your instructions and your "right place" comments, it seems that lacking your plane's cowl to prepare the engine position, I should set the engine at 1/2 degree down, and then figure some way to align the cowling to the spinner with 3/16" clearance all around, by shimming the engine until the cowling lays on the fuselage smoothly? > --Bob Steward > > Gary L Vogt wrote: > >> I could rehash this again for the umpteenth time . . . . but, >> >> suffice it to say, all engines are not aligned the same. When you have 3/4 inches clearance at the prop, it's not such a big deal. When you have 3/16 inches clearance, it makes a difference. >> >> When aligned to the cowling, the engine is down about .5 degrees wrt the canopy rails. >> >> >> ________________________________ >> From: "n76lima@mindspring.com" >> To: teamgrumman@yahoo.com >> Sent: Friday, March 29, 2013 1:09 PM >> Subject: Re: N28697: Jaguar cowling >> >> >> Are you saying it was in the "wrong" place before, or did it match his cowling location, but not yours? >> --Bob Steward >> >> With the engine in the right place, fitting the cowling is pretty easy. ________________________________ Message 2 _____________________________________ Time: 11:17:38 AM PST US From: Gary L Vogt Subject: Re: TeamGrumman-List: Re: N28697: Jaguar cowling Ned,=0A=0AThis was in response to the post of pre-fitting to which you resp onded.=0A=0A=0A________________________________=0A From: 923TE <923te@att.n et>=0ATo: Ned Thomas <923te@att.net> =0ASent: Sunday, March 31, 2013 8:02 A M=0ASubject: Re: TeamGrumman-List: Re: N28697: Jaguar cowling=0A =0A--> Tea mGrumman-List message posted by: 923TE <923te@att.net>=0A=0AHi Gary and Bob ,=0AThis looks like a discussion between the two of you. I haven't seen any of the emails posted to teamgrumman until this last one where my name is m entioned. Maybe this last post wasn't meant for the list? I'm only respondi ng to the two of you. I really don't want to hash this all out again in pub lic.=0A=0AMy issues with your work, Gary, were primarily that you forgot to do what I ask about aligning the engine to the original factory cowl. As I look back on it, I think perhaps you didn't align my engine to the factory cowl because you didn't believe that was valid. We chased that a bit and I got some engine alignment data from the factory and forwarded that to you. Whether that was helpful or valid or not is another subject.=0A=0ABack to my Jaguar cowl.- You had the Jag cowl aligned with the engine quite well. =0AAfter I got home, I discovered that the pilot side upper mount nut had n o bolt threads showing through and tightened it to factory specs. This move d the engine up and left quite a bit so that the cowl was now out of alignm ent. =0A=0AHowever, now my Tiger flew straight and level with all trim tabs neutral. This is how it flew prior to the upper left engine mount bolt bei ng "loose." This fact along with the factory telling me that proper engine alignment is determined by aligning the engine with the factory cowl confir ms in my mind that my engine is in the designed alignment. I did replace th e Jag with the factory cowl and the engine is now aligned with the factory cowl.=0A=0AAnother issue with the Jag cowl was that the bottom corners did not match my fuselage. Also, the spinner flange on the cowl was sticking ou t about 3/8" more than the MT spinner and the gap between the spinner and c owl was about 3/4". These things led me to look into refitting the Jag cowl . When I tried to align the cowl the right side was now not long enough. It was past the firewall flange screw holes. These are the reasons I extended the Jag cowl basically back to its pre-trimmed state and started over with installing it.=0A=0AThe fact that my factory cowl was still quite "new" ma y be why the factory engine alignment method still works on my plane while you have found it doesn't work on the older 1970's planes. Or at least its inconsistent? I don't know. Maybe the engine mounts move with time and the cowl stretches? =0A=0AThe factory told me that the lower cowl is drilled in a jig and that they are all the same when coming out of that jig. The cowl is then mounted and the engine alignment is compared to the cowl. If the e ngine is out of alignment specs then it is shimmed until it matches the cow l. They usually use the same number of shims but sometimes have to use more .=0A=0AIt would be interesting to mount the Jag into the factory jig, drill the holes and see how well it aligns.....=0A=0A=0AThat's my summary. Yes, I'm probably more demanding than some and in my case it would have been muc h easier to have re-started with new parts but I didn't want to spend that much more for those new parts.- The major hurdle at the time Gary install ed the Jag was getting the STC approved on my AG5B. That was a big one and Gary did a great job of getting it approved so quickly.=0A=0AHope this help s,=0ABest Regards,=0ANed=0A=0A=0A=0AOn Mar 31, 2013, at 1:01 AM, Gary L Vog t wrote:=0A=0A--> TeamGrumman-List message posted b y: Gary L Vogt =0A=0ADuring the initial cowling fabr ication, I made the assumption that each engine mount required one shim bet ween the engine and the bushing. I installed a mockup engine on new Lord mo unts on a 78 Tiger, N28840, using one shim on each mount. I laid up the new cowling using this as a starting point. =0A=0AWhen I installed the first c owling, actually a fiberglass 'splash,' on N119ST, it fit well using the sa me 'one shim per mount.' =0A=0AWhen I installed the second prototype, the f irst one flown, on N119ST, it also fit well with just one shim per mount. =0A=0AI installed the splash on John Bunker's Traveler. It didn't have any shims. It fit well. =0A=0AThe first complete cowling was installed on N2874 7. 747 required 2 shims on each top mount. =0A=0AEach of the first 5 cowlin gs was installed on each plane using a trial and error method like that in the installation instructions. a lot of work. =0A=0AIt was at this point th at I started asking for feedback regarding the number of shims on Tigers. I also asked for the distance between the firewall and the back of the aft s pinner bulkhead. The answers I got were varied and inconsistent. =0A=0ANed wanted his cowling pre-fitted so he didn't have to wait very long. At that time, I had a wingless Tiger, N29348, in a neighboring hangar. To save time , I installed the cowling from N28747 onto 348. N28348 required 2 thick shi ms on the left and one thick plus one thin shim on the right in order for t he cowling from N28747 to fit properly. After the new Jaguar cowling was co mpletely fitted to N28348, I fit the lower cowling of the new Jaguar cowlin g to N28747 just to check. It fit fine. That cowling was installed on Ned's plane. Ned didn't like the fact that his engine needed shims to fit the co wling since he thought his original AG5B cowling was perfect and it fit wel l. =0A=0AFast forward. =0A=0AI built a mockup for the Jaguar cowling using an AA1B, Cheetah engine mount, and the same mockup engine used in the origi nal Jaguar cowling fabrication. I fit my cowling to the AA1B mockup and it required one thin shim on the upper right. I measured the thrust angle at . 3 degrees down on the left side (no shim side) and .5 down on the right sid e. =0A=0AI then took the cowling from N28747 and installed it on N28697. It required 2 thick shims on the right and 2 thick plus one thin shim on the left. When done, the engine was .6 degrees down on the left and .4 degrees down on the right. =0A=0AThe question that has been posed is: How well did the original cowling fit on N28697?- =0A=0A697 came to me with one shim o n each mount. The engine was 1 degree up WRT the fuselage waterline. (thrus t angle was not the same for each side.). The cowling fit OK. The engine lo oked like it was up just a bit, but not bad. Most people, let's just say 'n o one' except me, would ever notice.- =0A=0ASo, why all the fuss?- If t he original cowling fit with the engine as is, what's the big deal with whe re the engine is?- =0A=0AWhen I look at a plane, I see all sorts of poor fitting parts. Most, if not all, of the cowlings don't fit worth a damn. Wi th 3/4 inches (or more) between the spinner bulkhead and the cowling, it ca n be off a lot and still look acceptable. Most people don't care. I'm an ob sessive compulsive so it does matter to me. =0A=0AThe space between the rea r spinner bulkhead and Jaguar cowling is just 3/16 inches. The side-to-side location is less than 1/16 inches. The gap around the openings and cowling halves is less than .065 inches. =0A=0ASince my installation requirements are likely more stringent than most, I'm not selling anymore cowlings that aren't pre-fitted to a known installation. It'll cost more, but it will sav e the installer a lot of headaches. =0A=0AGary=0ASent from my iPad=0A=0AOn Mar 30, 2013, at 12:18 AM, Bob Steward wrote:=0A =0A> What I am asking is: Did the engine line up with HIS cowling?- Or wa s your reference to "right place", saying that it did not match his cowl, a nd that once you re-aligned the engine, your cowl also lined up with it?=0A > If you mean that the engine needs to be aligned differently for your cowl , how can those of us that do not have your plane handy to test fit a compl eted cowl, figure out the "right place", before starting to test fit an unt rimmed cowl?=0A> I can measure the thrust angle of 1/2 degree down with my digital level.- Not sure about the offset to the (right) side.- Could p robably measure from firewall to some points on the engine, if I knew what those measurements were.=0A> =0A> Given only the information in your instru ctions and your "right place" comments, it seems that lacking your plane's cowl to prepare the engine position, I should set the engine at 1/2 degree down, and then figure some way to align the cowling to the spinner with 3/1 6" clearance all around, by shimming the engine until the cowling lays on t he fuselage smoothly?=0A> --Bob Steward=0A> =0A> Gary L Vogt wrote:=0A> =0A>> I could rehash this again for the umpteenth time . . . . but, =0A>> =0A>> suffice it to say, all engines are not aligned th e same.- When you have 3/4 inches clearance at the prop, it's not such a big deal.- When you have 3/16 inches clearance, it makes a difference.- =0A>> =0A>> When aligned to the cowling, the engine is down about .5 degre es wrt the canopy rails.=0A>> =0A>> =0A>> ________________________________ =0A>> From: "n76lima@mindspring.com" =0A>> To: team grumman@yahoo.com =0A>> Sent: Friday, March 29, 2013 1:09 PM=0A>> Subject: Re: N28697: Jaguar cowling=0A>> =0A>> =0A>> Are you saying it was in the "w rong" place before, or did it match his cowling location, but not yours?=0A >> --Bob Steward=0A>> =0A>> With the engine in the right place, fitting the =- - - - - - - - - - - - - - - -Matt Dralle ======== ________________________________ Message 3 _____________________________________ Time: 11:41:04 AM PST US From: Gary L Vogt Subject: Re: TeamGrumman-List: Re: N28697: Jaguar cowling Ned,=0A=0A=A2 The MT prop spinner is in a different position than the stock FP prop.=0A=A2 We never measured the angle on your engine befo re and after.=0A=A2 Regardless of what the factory says about alignme nt, experience shows that a down thrust angle makes the plane more stable d uring power changes. =C2-It also makes the plane faster.=0A=A2 If y ou had wanted the cowling aligned to your original factory engine location, then I wouldn't have pre-aligned and fitted the cowling before you got her e. =C2-You didn't make that clear.=0A=A2 Why do you think the facto ry alignment is the preferred alignment?=0A=A2 The AG5B has different screw spacing on the bottom than the AA5B. I don't recall the bottom not f itting. =C2-If there was a problem with matching the fuselage, I don't re call. =C2-I measured the width of my cowling and compared it to a 91 AG5B cowling; it is exactly the same.=0A=0ASee attached pics=0A=0APic 2626 is a n AG5B cowling at 42 3/16 inches.=0APic 2628 is a Jaguar cowling fresh out of the tooling. =C2-There is a little parallax but it's also 42 3/16 inch es=0A=0AGary=0A=0A=0A=0A________________________________=0A From: 923TE <92 3te@att.net>=0ATo: Ned Thomas <923te@att.net> =0ASent: Sunday, March 31, 20 13 8:02 AM=0ASubject: Re: TeamGrumman-List: Re: N28697: Jaguar cowling=0A ry and Bob,=0AThis looks like a discussion between the two of you. I haven' t seen any of the emails posted to teamgrumman until this last one where my name is mentioned. Maybe this last post wasn't meant for the list? I'm onl y responding to the two of you. I really don't want to hash this all out ag ain in public.=0A=0AMy issues with your work, Gary, were primarily that you forgot to do what I ask about aligning the engine to the original factory cowl. As I look back on it, I think perhaps you didn't align my engine to t he factory cowl because you didn't believe that was valid. We chased that a bit and I got some engine alignment data from the factory and forwarded th at to you. Whether that was helpful or valid or not is another subject.=0A =0ABack to my Jaguar cowl.=C2- You had the Jag cowl aligned with the engi ne quite well.=0AAfter I got home, I discovered that the pilot side upper m ount nut had no bolt threads showing through and tightened it to factory sp ecs. This moved the engine up and left quite a bit so that the cowl was now out of alignment. =0A=0AHowever, now my Tiger flew straight and level with all trim tabs neutral. This is how it flew prior to the upper left engine mount bolt being "loose." This fact along with the factory telling me that proper engine alignment is determined by aligning the engine with the facto ry cowl confirms in my mind that my engine is in the designed alignment. I did replace the Jag with the factory cowl and the engine is now aligned wit h the factory cowl.=0A=0AAnother issue with the Jag cowl was that the botto m corners did not match my fuselage. Also, the spinner flange on the cowl w as sticking out about 3/8" more than the MT spinner and the gap between the spinner and cowl was about 3/4". These things led me to look into refittin g the Jag cowl. When I tried to align the cowl the right side was now not l ong enough. It was past the firewall flange screw holes. These are the reas ons I extended the Jag cowl basically back to its pre-trimmed state and sta rted over with installing it.=0A=0AThe fact that my factory cowl was still quite "new" may be why the factory engine alignment method still works on m y plane while you have found it doesn't work on the older 1970's planes. Or at least its inconsistent? I don't know. Maybe the engine mounts move with time and the cowl stretches? =0A=0AThe factory told me that the lower cowl is drilled in a jig and that they are all the same when coming out of that jig. The cowl is then mounted and the engine alignment is compared to the cowl. If the engine is out of alignment specs then it is shimmed until it m atches the cowl. They usually use the same number of shims but sometimes ha ve to use more.=0A=0AIt would be interesting to mount the Jag into the fact ory jig, drill the holes and see how well it aligns.....=0A=0A=0AThat's my summary. Yes, I'm probably more demanding than some and in my case it would have been much easier to have re-started with new parts but I didn't want to spend that much more for those new parts.=C2- The major hurdle at the time Gary installed the Jag was getting the STC approved on my AG5B. That w as a big one and Gary did a great job of getting it approved so quickly.=0A =0AHope this helps,=0ABest Regards,=0ANed=0A=0A=0A=0AOn Mar 31, 2013, at 1: 01 AM, Gary L Vogt wrote:=0A=0A--> TeamGrumman-List message posted by: Gary L Vogt =0A=0ADuring the ini tial cowling fabrication, I made the assumption that each engine mount requ ired one shim between the engine and the bushing. I installed a mockup engi ne on new Lord mounts on a 78 Tiger, N28840, using one shim on each mount. I laid up the new cowling using this as a starting point. =0A=0AWhen I inst alled the first cowling, actually a fiberglass 'splash,' on N119ST, it fit well using the same 'one shim per mount.' =0A=0AWhen I installed the second prototype, the first one flown, on N119ST, it also fit well with just one shim per mount.=0A=0AI installed the splash on John Bunker's Traveler. It d idn't have any shims. It fit well. =0A=0AThe first complete cowling was ins talled on N28747. 747 required 2 shims on each top mount. =0A=0AEach of the first 5 cowlings was installed on each plane using a trial and error metho d like that in the installation instructions. a lot of work. =0A=0AIt was a t this point that I started asking for feedback regarding the number of shi ms on Tigers. I also asked for the distance between the firewall and the ba ck of the aft spinner bulkhead. The answers I got were varied and inconsist ent. =0A=0ANed wanted his cowling pre-fitted so he didn't have to wait very long. At that time, I had a wingless Tiger, N29348, in a neighboring hanga r. To save time, I installed the cowling from N28747 onto 348. N28348 requi red 2 thick shims on the left and one thick plus one thin shim on the right in order for the cowling from N28747 to fit properly. After the new Jaguar cowling was completely fitted to N28348, I fit the lower cowling of the ne w Jaguar cowling to N28747 just to check. It fit fine. That cowling was ins talled on Ned's plane. Ned didn't like the fact that his engine needed shim s to fit the cowling since he thought his original AG5B cowling was perfect and it fit well. =0A=0AFast forward. =0A=0AI built a mockup for the Jaguar cowling using an AA1B, Cheetah engine mount, and the same mockup engine us ed in the original Jaguar cowling fabrication. I fit my cowling to the AA1B mockup and it required one thin shim on the upper right. I measured the th rust angle at .3 degrees down on the left side (no shim side) and .5 down o n the right side. =0A=0AI then took the cowling from N28747 and installed i t on N28697. It required 2 thick shims on the right and 2 thick plus one th in shim on the left. When done, the engine was .6 degrees down on the left and .4 degrees down on the right. =0A=0AThe question that has been posed is : How well did the original cowling fit on N28697?=C2- =0A=0A697 came to me with one shim on each mount. The engine was 1 degree up WRT the fuselage waterline. (thrust angle was not the same for each side.). The cowling fit OK. The engine looked like it was up just a bit, but not bad. Most people, let's just say 'no one' except me, would ever notice.=C2- =0A=0ASo, why all the fuss?=C2- If the original cowling fit with the engine as is, what 's the big deal with where the engine is?=C2- =0A=0AWhen I look at a plan e, I see all sorts of poor fitting parts. Most, if not all, of the cowlings don't fit worth a damn. With 3/4 inches (or more) between the spinner bulk head and the cowling, it can be off a lot and still look acceptable. Most p eople don't care. I'm an obsessive compulsive so it does matter to me. =0A =0AThe space between the rear spinner bulkhead and Jaguar cowling is just 3 /16 inches. The side-to-side location is less than 1/16 inches. The gap aro und the openings and cowling halves is less than .065 inches. =0A=0ASince m y installation requirements are likely more stringent than most, I'm not se lling anymore cowlings that aren't pre-fitted to a known installation. It'l l cost more, but it will save the installer a lot of headaches. =0A=0AGary =0ASent from my iPad=0A=0AOn Mar 30, 2013, at 12:18 AM, Bob Steward wrote:=0A=0A> What I am asking is: Did the engine line up with HIS cowling?=C2- Or was your reference to "right place", saying tha t it did not match his cowl, and that once you re-aligned the engine, your cowl also lined up with it?=0A> If you mean that the engine needs to be ali gned differently for your cowl, how can those of us that do not have your p lane handy to test fit a completed cowl, figure out the "right place", befo re starting to test fit an untrimmed cowl?=0A> I can measure the thrust ang le of 1/2 degree down with my digital level.=C2- Not sure about the offse t to the (right) side.=C2- Could probably measure from firewall to some p oints on the engine, if I knew what those measurements were.=0A> =0A> Given only the information in your instructions and your "right place" comments, it seems that lacking your plane's cowl to prepare the engine position, I should set the engine at 1/2 degree down, and then figure some way to align the cowling to the spinner with 3/16" clearance all around, by shimming th e engine until the cowling lays on the fuselage smoothly?=0A> --Bob Steward =0A> =0A> Gary L Vogt wrote:=0A> =0A>> I could reha sh this again for the umpteenth time . . . . but, =0A>> =0A>> suffice it to say, all engines are not aligned the same.=C2- When you have 3/4 inches clearance at the prop, it's not such a big deal.=C2- When you have 3/16 i nches clearance, it makes a difference.=C2- =0A>> =0A>> When aligned to t he cowling, the engine is down about .5 degrees wrt the canopy rails.=0A>> =0A>> =0A>> ________________________________=0A>> From: "n76lima@mindspring .com" =0A>> To: teamgrumman@yahoo.com =0A>> Sent: F riday, March 29, 2013 1:09 PM=0A>> Subject: Re: N28697: Jaguar cowling=0A>> =0A>> =0A>> Are you saying it was in the "wrong" place before, or did it m atch his cowling location, but not yours?=0A>> --Bob Steward=0A>> =0A>> Wit h the engine in the right place, fitting the cowling is pretty easy.=0A=0A - =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- - ============= ________________________________ Message 4 _____________________________________ Time: 11:43:16 AM PST US From: Gary L Vogt Subject: Re: TeamGrumman-List: Re: N28697: Jaguar cowling two more pics=0A=0A=0A________________________________=0A From: 923TE <923t e@att.net>=0ATo: Ned Thomas <923te@att.net> =0ASent: Sunday, March 31, 2013 8:02 AM=0ASubject: Re: TeamGrumman-List: Re: N28697: Jaguar cowling=0A =0A and Bob,=0AThis looks like a discussion between the two of you. I haven't s een any of the emails posted to teamgrumman until this last one where my na me is mentioned. Maybe this last post wasn't meant for the list? I'm only r esponding to the two of you. I really don't want to hash this all out again in public.=0A=0AMy issues with your work, Gary, were primarily that you fo rgot to do what I ask about aligning the engine to the original factory cow l. As I look back on it, I think perhaps you didn't align my engine to the factory cowl because you didn't believe that was valid. We chased that a bi t and I got some engine alignment data from the factory and forwarded that to you. Whether that was helpful or valid or not is another subject.=0A=0AB ack to my Jaguar cowl.- You had the Jag cowl aligned with the engine quit e well.=0AAfter I got home, I discovered that the pilot side upper mount nu t had no bolt threads showing through and tightened it to factory specs. Th is moved the engine up and left quite a bit so that the cowl was now out of alignment. =0A=0AHowever, now my Tiger flew straight and level with all tr im tabs neutral. This is how it flew prior to the upper left engine mount b olt being "loose." This fact along with the factory telling me that proper engine alignment is determined by aligning the engine with the factory cowl confirms in my mind that my engine is in the designed alignment. I did rep lace the Jag with the factory cowl and the engine is now aligned with the f actory cowl.=0A=0AAnother issue with the Jag cowl was that the bottom corne rs did not match my fuselage. Also, the spinner flange on the cowl was stic king out about 3/8" more than the MT spinner and the gap between the spinne r and cowl was about 3/4". These things led me to look into refitting the J ag cowl. When I tried to align the cowl the right side was now not long eno ugh. It was past the firewall flange screw holes. These are the reasons I e xtended the Jag cowl basically back to its pre-trimmed state and started ov er with installing it.=0A=0AThe fact that my factory cowl was still quite " new" may be why the factory engine alignment method still works on my plane while you have found it doesn't work on the older 1970's planes. Or at lea st its inconsistent? I don't know. Maybe the engine mounts move with time a nd the cowl stretches? =0A=0AThe factory told me that the lower cowl is dri lled in a jig and that they are all the same when coming out of that jig. T he cowl is then mounted and the engine alignment is compared to the cowl. I f the engine is out of alignment specs then it is shimmed until it matches the cowl. They usually use the same number of shims but sometimes have to u se more.=0A=0AIt would be interesting to mount the Jag into the factory jig , drill the holes and see how well it aligns.....=0A=0A=0AThat's my summary . Yes, I'm probably more demanding than some and in my case it would have b een much easier to have re-started with new parts but I didn't want to spen d that much more for those new parts.- The major hurdle at the time Gary installed the Jag was getting the STC approved on my AG5B. That was a big o ne and Gary did a great job of getting it approved so quickly.=0A=0AHope th is helps,=0ABest Regards,=0ANed=0A=0A=0A=0AOn Mar 31, 2013, at 1:01 AM, Gar y L Vogt wrote:=0A=0A--> TeamGrumman-List message p osted by: Gary L Vogt =0A=0ADuring the initial cowli ng fabrication, I made the assumption that each engine mount required one s him between the engine and the bushing. I installed a mockup engine on new Lord mounts on a 78 Tiger, N28840, using one shim on each mount. I laid up the new cowling using this as a starting point. =0A=0AWhen I installed the first cowling, actually a fiberglass 'splash,' on N119ST, it fit well using the same 'one shim per mount.' =0A=0AWhen I installed the second prototype , the first one flown, on N119ST, it also fit well with just one shim per m ount.=0A=0AI installed the splash on John Bunker's Traveler. It didn't have any shims. It fit well. =0A=0AThe first complete cowling was installed on N28747. 747 required 2 shims on each top mount. =0A=0AEach of the first 5 c owlings was installed on each plane using a trial and error method like tha t in the installation instructions. a lot of work. =0A=0AIt was at this poi nt that I started asking for feedback regarding the number of shims on Tige rs. I also asked for the distance between the firewall and the back of the aft spinner bulkhead. The answers I got were varied and inconsistent. =0A =0ANed wanted his cowling pre-fitted so he didn't have to wait very long. A t that time, I had a wingless Tiger, N29348, in a neighboring hangar. To sa ve time, I installed the cowling from N28747 onto 348. N28348 required 2 th ick shims on the left and one thick plus one thin shim on the right in orde r for the cowling from N28747 to fit properly. After the new Jaguar cowling was completely fitted to N28348, I fit the lower cowling of the new Jaguar cowling to N28747 just to check. It fit fine. That cowling was installed o n Ned's plane. Ned didn't like the fact that his engine needed shims to fit the cowling since he thought his original AG5B cowling was perfect and it fit well. =0A=0AFast forward. =0A=0AI built a mockup for the Jaguar cowling using an AA1B, Cheetah engine mount, and the same mockup engine used in th e original Jaguar cowling fabrication. I fit my cowling to the AA1B mockup and it required one thin shim on the upper right. I measured the thrust ang le at .3 degrees down on the left side (no shim side) and .5 down on the ri ght side. =0A=0AI then took the cowling from N28747 and installed it on N28 697. It required 2 thick shims on the right and 2 thick plus one thin shim on the left. When done, the engine was .6 degrees down on the left and .4 d egrees down on the right. =0A=0AThe question that has been posed is: How we ll did the original cowling fit on N28697?- =0A=0A697 came to me with one shim on each mount. The engine was 1 degree up WRT the fuselage waterline. (thrust angle was not the same for each side.). The cowling fit OK. The en gine looked like it was up just a bit, but not bad. Most people, let's just say 'no one' except me, would ever notice.- =0A=0ASo, why all the fuss? - If the original cowling fit with the engine as is, what's the big deal with where the engine is?- =0A=0AWhen I look at a plane, I see all sorts of poor fitting parts. Most, if not all, of the cowlings don't fit worth a damn. With 3/4 inches (or more) between the spinner bulkhead and the cowlin g, it can be off a lot and still look acceptable. Most people don't care. I 'm an obsessive compulsive so it does matter to me. =0A=0AThe space between the rear spinner bulkhead and Jaguar cowling is just 3/16 inches. The side -to-side location is less than 1/16 inches. The gap around the openings and cowling halves is less than .065 inches. =0A=0ASince my installation requi rements are likely more stringent than most, I'm not selling anymore cowlin gs that aren't pre-fitted to a known installation. It'll cost more, but it will save the installer a lot of headaches. =0A=0AGary=0ASent from my iPad =0A=0AOn Mar 30, 2013, at 12:18 AM, Bob Steward wr ote:=0A=0A> What I am asking is: Did the engine line up with HIS cowling? - Or was your reference to "right place", saying that it did not match hi s cowl, and that once you re-aligned the engine, your cowl also lined up wi th it?=0A> If you mean that the engine needs to be aligned differently for your cowl, how can those of us that do not have your plane handy to test fi t a completed cowl, figure out the "right place", before starting to test f it an untrimmed cowl?=0A> I can measure the thrust angle of 1/2 degree down with my digital level.- Not sure about the offset to the (right) side. - Could probably measure from firewall to some points on the engine, if I knew what those measurements were.=0A> =0A> Given only the information in your instructions and your "right place" comments, it seems that lacking yo ur plane's cowl to prepare the engine position, I should set the engine at 1/2 degree down, and then figure some way to align the cowling to the spinn er with 3/16" clearance all around, by shimming the engine until the cowlin g lays on the fuselage smoothly?=0A> --Bob Steward=0A> =0A> Gary L Vogt wrote:=0A> =0A>> I could rehash this again for the ump teenth time . . . . but, =0A>> =0A>> suffice it to say, all engines are not aligned the same.- When you have 3/4 inches clearance at the prop, it's not such a big deal.- When you have 3/16 inches clearance, it makes a dif ference.- =0A>> =0A>> When aligned to the cowling, the engine is down abo ut .5 degrees wrt the canopy rails.=0A>> =0A>> =0A>> ______________________ __________=0A>> From: "n76lima@mindspring.com" =0A> > To: teamgrumman@yahoo.com =0A>> Sent: Friday, March 29, 2013 1:09 PM=0A>> Subject: Re: N28697: Jaguar cowling=0A>> =0A>> =0A>> Are you saying it was in the "wrong" place before, or did it match his cowling location, but not yours?=0A>> --Bob Steward=0A>> =0A>> With the engine in the right place, f =========== ________________________________ Message 5 _____________________________________ Time: 12:18:45 PM PST US From: Gary L Vogt Subject: TeamGrumman-List: AA1B Jaguar cowling mockup The really interesting thing about the Cheetah engine mount is that it is V ERY difficult to put shims between the engine and the shock mount. -The s hape of the shocks and the way they sit throws off the alignment A LOT if a shim is added. -Adding shims makes installing the bolts impossible. - =0A=0AI initially tried installing the mockup engine with one shim on each. -I couldn't get the bolts in. -After messing with it for an hour or mo re, I gave up for the day.=0A=0AThe next day, I removed all of the shims an d started over. -When I installed the Jag cowling with no shims, I was su rprised how close the cowling fit with the stock Cheetah mount and no shims . -Pic 3018s=0A=0AI took another pic before I added the shim. -If you l ook closely, you can see the engine is just slightly up and to the right. -That's how a stock, unadjusted, Cheetah cowling would fit. Pic 3019s=0A =0AInstead of removing the upper right bolt to install a shim, I cut a slot in a thin shim, loosened the bolt, and installed the shim. -With the thi n shim in the upper right, the engine is exactly centered on the cowling. -=0A-----=0A=0ABob, if you and Dave are installing the cowling, I'd recom mend starting with the engine roughly .3 to .6 degrees down; measured on th e left side or right side, I don't know. -It seems like the angle is not symmetric side-to-side. -Start with one shim in each location. -Adjust it from there.=0A=0ANote: On the cowling I'm currently installing, it looks like the left side of the spinner bulkhead is about .050 to .060 inches cl oser to the cowling than the right side. -I plan to block sand that side until it's the same as the right. -=0A ________________________________ Message 6 _____________________________________ Time: 07:21:54 PM PST US From: 923TE <923te@att.net> Subject: TeamGrumman-List: Speed Mod - Engine Down Thrust Angle Gary posted: =A2 Regardless of what the factory says about alignment, experience sh ows that a down thrust angle makes the plane more stable during power change s. It also makes the plane faster. Ned posts: I'm interested in the experience that you mention. Is that from the WWII air craft designs you mentioned a few years ago? Or have you actually flown your Tiger with 0 then 2 degrees down angle? That would be very interesting flig ht tests. If you haven't tried that I might do that sometime just to see wha t happens. I've been racing my Tiger for several years now. One of the fun things about doing that is getting to hang out with all the other racers. Nobody ever me ntions a speed advantage with anything but zero thrust angle. That is, they a lways say the same thing and that is you need to have zero thrust angle for m aximum speed. Maybe they are all wrong? ________________________________ Message 7 _____________________________________ Time: 08:52:34 PM PST US From: Gary L Vogt Subject: Re: TeamGrumman-List: Speed Mod - Engine Down Thrust Angle I don't know about 2 degrees down. =C2-2 Degrees is a lot. =C2-One thic k shim is worth about .5 degrees.=0A---------------=0AI double checked the AA1B mockup I'm using for pre-fitting the Jaguar cowling. =C2-=0A=0ACanop y rail: =C2-Left at .9 degrees up. =C2-=0A=C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- Right at 1.1 degrees up.=0A=0AEngine: =C2-Left at .8 degrees up. =C2-i.e., .1 degrees down=0A=C2- =C2- =C2- =C2- =C2- =C2- Right at .9 degrees up. =C2-i.e., .2 degrees down=0A=0AThat means the mockup engine is somewhere around .1 to .2 degrees down. =C2-So, worst case scenario, my cowling is, at most, .5 degree dow n.=0A=0ANote: =C2-I measured the engine in several different places and g ot different answers at each location. =C2-Measuring the cylinder bases, which, one would think, would be on the centerline, varied .1 degrees on ea ch side. =C2-That is, the front cylinder might show .2 down thrust and th e rear .1 down or vice versa. =C2-Measuring at the lifter body bosses yie lded values not consistent with either. =C2-=0A---------------=0A=0AWhen I get the upper cowling on N28697 so I can open it, I'll double check it. =0A---------------=0A=0ADown thrust: =C2-I did a lot of reading regarding down thrust. =C2-RC modelers use down thrust to make power changes less of a control issue. =C2-Straight and level, when the power is pulled back , the plane doesn't sink as fast sink the engine is no longer pulling it do wn. =C2-Likewise, when power is applied, there is less need for down elev ator since the engine is pulling down. =C2-=0A=0AThe T-28 has 5 degrees d own thrust angle.=0A=0ADuring WWII, it was found, mostly on big radials, th at the plane was faster with the engine in a down thrust position. =C2-Th is was due to reduced trim drag. =C2-As you go faster, if you don't have to trim the nose down, there is less trim drag. =C2-=0A----------------- =0A=0AGalloping Ghost: =C2-The trim tab failed on Galloping Ghost causing an abrupt pitch up. =C2-At those speeds, the trim is at the limit trying to keep the plane flying straight. =C2-Why not point the nose down and s hed all that trim requirement . . . or at least a large portion of it?=0A-- ---------------=0A=0ANACA 64-415 Mod. =C2-That's our airfoil. =C2-It's pretty close to a Clark Y (if you rotate the Clark Y on it's axis 2.5 degre es.) =C2-The Clark Y has best L/D at around 2 degrees down AoA. =C2-Or, about where the -415 is when the Grumman is at 2.5 degrees down at the wat erline. =C2-=0A=0ASo, you want the plane to be nose down. =C2-Why not l et the engine pull it down, reduce trim drag, and put the airfoil at minimu m L/D? =C2-And, get less pitch change when changing power settings?=0A=0A Gary=0A=0A=C2-=0A=0A________________________________=0A From: 923TE <923t e@att.net>=0ATo: "teamgrumman-list@matronics.com" =0ASent: Sunday, March 31, 2013 7:20 PM=0ASubject: TeamGrumman-List : Speed Mod - Engine Down Thrust Angle=0A =0A=0AGary posted:=0A=A2 Re gardless of what the factory says about alignment, experience shows that a down thrust angle makes the plane more stable during power changes. =C2-I t also makes the plane faster.=0A=0ANed posts:=0AI'm interested in the expe rience that you mention. Is that from the WWII aircraft designs you mention ed a few years ago? Or have you actually flown your Tiger with 0 then 2 deg rees down angle? That would be very interesting flight tests. If you haven' t tried that I might do that sometime just to see what happens.=0A=0AI've b een racing my Tiger for several years now. One of the fun things about doin g that is getting to hang out with all the other racers. Nobody ever mentio ns a speed advantage with anything but zero thrust angle. That is, they alw ays say the same thing and that is you need to have zero thrust angle for m ======== ________________________________ Message 8 _____________________________________ Time: 11:41:35 PM PST US From: 923TE <923te@att.net> Subject: Re: TeamGrumman-List: Speed Mod - Engine Down Thrust Angle ________________________________ Message 9 _____________________________________ Time: 11:53:03 PM PST US Subject: TeamGrumman-List: Speed Mod - Engine Down Thrust Angle From: 923TE <923te@att.net> ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message teamgrumman-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/TeamGrumman-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/teamgrumman-list Browse Digests http://www.matronics.com/digest/teamgrumman-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.