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teamgrumman(at)yahoo.com
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 Posted: Fri Mar 29, 2013 10:44 am Post subject: N28697: Jaguar cowling |
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With the engine in the right place, fitting the cowling is pretty easy.
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| Posted: Fri Mar 29, 2013 10:45 am Post subject: N28697: Jaguar cowling |
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Even the upper fits pretty well before trimming.
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Discover
Joined: 26 Feb 2007
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| Posted: Fri Mar 29, 2013 4:53 pm Post subject: N28697: Jaguar cowling |
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I'll second that!
For sure!
On Mar 29, 2013, at 1:43 PM, Gary L Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
With the engine in the right place, fitting the cowling is pretty easy.
<IMG_3124.JPG>
[quote][b]
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teamgrumman(at)yahoo.com
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| Posted: Sat Mar 30, 2013 10:02 pm Post subject: N28697: Jaguar cowling |
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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 <n76lima(at)mindspring.com> wrote:
| Quote: | 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 <teamgrumman(at)yahoo.com> 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(at)mindspring.com" <n76lima(at)mindspring.com>
> To: teamgrumman(at)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.
|
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teamgrumman(at)yahoo.com
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| Posted: Sun Mar 31, 2013 10:17 am Post subject: N28697: Jaguar cowling |
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Ned,
This was in response to the post of pre-fitting to which you responded.
From: 923TE <923te(at)att.net>
To: Ned Thomas <923te(at)att.net>
Sent: Sunday, March 31, 2013 8:02 AM
Subject: Re: Re: N28697: Jaguar cowling
--> TeamGrumman-List message posted by: 923TE <923te(at)att.net (923te(at)att.net)>
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 <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
--> TeamGrumman-List message posted by: Gary L Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)>
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 <n76lima(at)mindspring.com (n76lima(at)mindspring.com)> wrote:
| Quote: | 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 <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> 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(at)mindspring.com (n76lima(at)mindspring.com)" <n76lima(at)mindspring.com (n76lima(at)mindspring.com)>
> To: teamgrumman(at)yahoo.com (teamgrumman(at)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.http://www.ma -Matt Dralle, List Admin. href="http://www.matronics.com/contribution" target="_blank">http://ww=======================
|
[quote][b]
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teamgrumman(at)yahoo.com
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| Posted: Sun Mar 31, 2013 10:41 am Post subject: N28697: Jaguar cowling |
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|
Ned,
• The MT prop spinner is in a different position than the stock FP prop.
• We never measured the angle on your engine before and after.
• Regardless of what the factory says about alignment, experience shows that a down thrust angle makes the plane more stable during power changes. It also makes the plane faster.
• If you 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 here. You didn't make that clear.
• Why do you think the factory alignment is the preferred alignment?
• The AG5B has different screw spacing on the bottom than the AA5B. I don't recall the bottom not fitting. If there was a problem with matching the fuselage, I don't recall. I measured the width of my cowling and compared it to a 91 AG5B cowling; it is exactly the same.
See attached pics
Pic 2626 is an AG5B cowling at 42 3/16 inches.
Pic 2628 is a Jaguar cowling fresh out of the tooling. There is a little parallax but it's also 42 3/16 inches
Gary
From: 923TE <923te(at)att.net>
To: Ned Thomas <923te(at)att.net>
Sent: Sunday, March 31, 2013 8:02 AM
Subject: Re: TeamGrumman-List: Re: N28697: Jaguar cowling
--> TeamGrumman-List message posted by: 923TE <923te(at)att.net (923te(at)att.net)>
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 <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
--> TeamGrumman-List message posted by: Gary L Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)>
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 <n76lima(at)mindspring.com (n76lima(at)mindspring.com)> wrote:
| Quote: | 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 <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> 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(at)mindspring.com (n76lima(at)mindspring.com)" <n76lima(at)mindspring.com (n76lima(at)mindspring.com)>
> To: teamgrumman(at)yahoo.com (teamgrumman(at)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.http://www.ma -Matt Dralle, List Admin. href="http://www.matronics.com/contribution" target="_blank">http://ww=======================
|
| | - The Matronics TeamGrumman-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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teamgrumman(at)yahoo.com
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| Posted: Sun Mar 31, 2013 10:43 am Post subject: N28697: Jaguar cowling |
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two more pics
From: 923TE <923te(at)att.net>
To: Ned Thomas <923te(at)att.net>
Sent: Sunday, March 31, 2013 8:02 AM
Subject: Re: TeamGrumman-List: Re: N28697: Jaguar cowling
--> TeamGrumman-List message posted by: 923TE <923te(at)att.net (923te(at)att.net)>
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 <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
--> TeamGrumman-List message posted by: Gary L Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)>
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 <n76lima(at)mindspring.com (n76lima(at)mindspring.com)> wrote:
| Quote: | 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 <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> 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(at)mindspring.com (n76lima(at)mindspring.com)" <n76lima(at)mindspring.com (n76lima(at)mindspring.com)>
> To: teamgrumman(at)yahoo.com (teamgrumman(at)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.http://www.ma -Matt Dralle, List Admin. href="http://www.matronics.com/contribution" target="_blank">http://ww=======================
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