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
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| Subject: | 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 <teamgrumman@yahoo.com> 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 <n76lima@mindspring.com> 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 <teamgrumman@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@mindspring.com" <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
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| Subject: | 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 <teamgrumman@yahoo.com> wrote:=0A=0A--> TeamGrumman-List message posted b
y: Gary L Vogt <teamgrumman@yahoo.com>=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 <n76lima@mindspring.com> 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 <teamgrumman@y
ahoo.com> 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" <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
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| Subject: | 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 <teamgrumman@yahoo.com> wrote:=0A=0A--> TeamGrumman-List
message posted by: Gary L Vogt <teamgrumman@yahoo.com>=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 <n76lim
a@mindspring.com> 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 <teamgrumman@yahoo.com> 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" <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
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| Subject: | 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 <teamgrumman@yahoo.com> wrote:=0A=0A--> TeamGrumman-List message p
osted by: Gary L Vogt <teamgrumman@yahoo.com>=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 <n76lima@mindspring.com> 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 <te
amgrumman@yahoo.com> 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" <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
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| Subject: | 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
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| Subject: | 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
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| Subject: | Re: 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" <teamgrumman-list@matroni
cs.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
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| Subject: | Re: Speed Mod - Engine Down Thrust Angle |
Message 9
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| Subject: | Speed Mod - Engine Down Thrust Angle |
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