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ceengland7(at)gmail.com
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 Posted: Sun Apr 09, 2017 1:31 pm Post subject: Kolb Twinstar (original version) info request |
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OK, now that I've got that short nose Kolb bit out of my system....
I'm now the proud owner of an N-numbered early Kolb Twinstar
(restoration project). IIRC, its serial number is in the low 20's range.
A little rusty, but we've peeled the fabric on one wing & the aluminum
seems to be in good shape, with very little corrosion, considering that
it spent its entire past life in central FL.
This one's got a Rotax 503 (converted from single to dual carbs, and to
free air cooling) that seems to be in great shape. The previous owner is
a close friend who was the builder. I trust what he tells me, and he
says that it always cooled fine running it free-air with some added
ducting.
I'll be replacing hardware, 'soft' parts, etc, but don't intend on doing
a showplane restoration; just a safe, nice flying 'after supper' flyer.
I've got the plans for the plane, but I'm hoping that you experienced
Kolbers can share any suggested mods to these early models, that will
make them safer/more durable/etc. Is there a published list of any/all
service bulletins or recommended updates? For instance, I've seen the
advice to add braces to the tailspring stinger. And I know that the
later Twinstars have mass balances on at least some of the control
surfaces; is it recommended to add them to the early models? This one
does not have any mass balances anywhere.
Who's recovered one? Any issues when you drilled out the rivets to
remove the ailerons, etc for recovering?
Any advice will be appreciated.
Thanks,
Charlie
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
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| Posted: Sun Apr 09, 2017 2:59 pm Post subject: Kolb Twinstar (original version) info request |
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Charlie E/Kolbers:
I have recovered a bunch of them. All that I tore up and a few I didn't.
Drilling rivets can be accomplished once you have the mandrels removed. It takes a 1/16" punch, or you can use a pulled mandrel, grind the end flat, hold with vise grips, and knock out with a hammer. The rivet needs to be held to prevent spinning. I grind a V in the end of a hack saw blade with sharp beveled edges. Use that to push up under the rivet to lock it in place while drilling.
4130 airframes should be tube sealed when fabricated. 99% of Kolbs probably have never been tube sealed. Their builders probably never heard of tube sealing. 4130 rusts from inside out if not sealed. That would worry me with an old fuselage, especially a Twinstar. I can't remember exactly what the fuselage looks like other that the root tube that seats and stuff are attached to. This I would make sure is rust free on the inside.
I helped Brother Jim rebuild Adriel Heisey's Twinstar, Navajo Nation pilot that shot aerial photos published in Nat Geo and other pubs, that he crashed in a wind storm. It was frightening when we started cutting tubing. Most were rusted well beyond serviceability. Here are photos of his Twinstar:
https://uanews.arizona.edu/story/aerial-photos-of-archaeological-sites-on-exhibit-at-state-museum
I don't recall anyone flying a free air cooled Rotax on a Kolb successfully. Yours may be an exception.
Don't know of any published updates for the Twinstar. It was not a popular model and kits only produced a couple years.
Strong lateral bracing of the leading edge of the wing is extremely important to me. Poor/weak lateral bracing can lead to leading edge failure. This causes the Kolb to stop flying immediately.
Lower tail post bracing makes it last longer.
I don't know a whole lot about the Twinstar. The one Kolb model I never flew.
john h
mkIII
Titus, Alabama
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John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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ceengland7(at)gmail.com
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| Posted: Sun Apr 09, 2017 4:15 pm Post subject: Kolb Twinstar (original version) info request |
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Thanks, John. I wasn't sure about how rugged the tubes would be when
driving out mandrels, etc. I use similar tricks on the heavier
experimentals I've owned. I've got a spring loaded center punch that I
ground to a flat nosed, straight shaft, & use it to punch out driven
rivets after drilling the heads. I also use small, flush cutting 'dykes'
(diagonal wire cutters) to grab pop rivet heads; same idea as your hack
saw 'V'.
I will be checking the 4130 pieces for integrity. One trick I was taught
that's used on Cubs, Taylorcraft, etc is to wrap the tube with something
to protect from scratching & squeeze it with a pair of 'channel lock'
pliers. Not a perfect test, but if the tube gives at all, you know
you've got a problem.
The free air cooling thing I'll be looking at, but he told me that he
had added some ducting (haven't seen it all assembled yet) so he may
well have added a 'collector' on the input side & an exit duct that ends
near the prop for extraction. We'll see.
We've pulled the fabric off one side of a wing, & I don't recall seeing
lateral bracing of the leading edge ribs. But I wasn't looking for it.
Will definitely make sure it has bracing in place before recover.
Speaking of which, has anyone wrapped the leading edge ribs with very
thin gauge aluminum sheet before covering? It's done on some heavier
fabric wing a/c to provide somewhat of a D-cell (lateral bracing) and
also provide a smooth, more aerodynamic leading edge (nothing like a
little aero cleanup  ).
I really don't want to stray too far from the original design, but I'm
curious about any mods people have been successful with.
Thanks,
Charlie
On 4/9/2017 5:58 PM, John Hauck wrote:
[quote]
Charlie E/Kolbers:
I have recovered a bunch of them. All that I tore up and a few I didn't.
Drilling rivets can be accomplished once you have the mandrels removed. It takes a 1/16" punch, or you can use a pulled mandrel, grind the end flat, hold with vise grips, and knock out with a hammer. The rivet needs to be held to prevent spinning. I grind a V in the end of a hack saw blade with sharp beveled edges. Use that to push up under the rivet to lock it in place while drilling.
4130 airframes should be tube sealed when fabricated. 99% of Kolbs probably have never been tube sealed. Their builders probably never heard of tube sealing. 4130 rusts from inside out if not sealed. That would worry me with an old fuselage, especially a Twinstar. I can't remember exactly what the fuselage looks like other that the root tube that seats and stuff are attached to. This I would make sure is rust free on the inside.
I helped Brother Jim rebuild Adriel Heisey's Twinstar, Navajo Nation pilot that shot aerial photos published in Nat Geo and other pubs, that he crashed in a wind storm. It was frightening when we started cutting tubing. Most were rusted well beyond serviceability. Here are photos of his Twinstar:
https://uanews.arizona.edu/story/aerial-photos-of-archaeological-sites-on-exhibit-at-state-museum
I don't recall anyone flying a free air cooled Rotax on a Kolb successfully. Yours may be an exception.
Don't know of any published updates for the Twinstar. It was not a popular model and kits only produced a couple years.
Strong lateral bracing of the leading edge of the wing is extremely important to me. Poor/weak lateral bracing can lead to leading edge failure. This causes the Kolb to stop flying immediately.
Lower tail post bracing makes it last longer.
I don't know a whole lot about the Twinstar. The one Kolb model I never flew.
john h
mkIII
Titus, Alabama
--
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
|
| Posted: Sun Apr 09, 2017 4:58 pm Post subject: Kolb Twinstar (original version) info request |
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" We've pulled the fabric off one side of a wing, & I don't recall seeing lateral bracing of the leading edge ribs. But I wasn't looking for it.'
Charlie E/Gents:
I didn't say "leading edge ribs", I said "leading edge." Lateral bracing on the leading edge tube keeps the noses of the ribs in column. Weak lateral, or little or no lateral bracing will allow the ribs to come out of column and fail. I know this by experience.
Homer Kolb did not wrap the leading edge with alum sheet, and did not recommend doing this. He felt his bow tip design and the valleys between ribs improved slow speed flight and decreased stall speed. Kolbs all use the same airfoil, all models, and have always been great slow speed performers, long before VGs. Homer's idea of flying was low and slow, right down in the tree tops to stay in touch with what was going on down there. He liked to fly with the birds. Thus the large ailerons and high lift wing.
john h
mkIII
Titus, Alabama
--
| | - The Matronics Kolb-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:
http://www.matronics.com/Navigator?Kolb-List |
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_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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ceengland7(at)gmail.com
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| Posted: Sun Apr 09, 2017 7:11 pm Post subject: Kolb Twinstar (original version) info request |
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Yes, you did. Sorry; I've got to adjust to having 3 spars instead of 2.
Thank you for the info.
Charlie
On 4/9/2017 7:57 PM, John Hauck wrote:
[quote]
" We've pulled the fabric off one side of a wing, & I don't recall seeing lateral bracing of the leading edge ribs. But I wasn't looking for it.'
Charlie E/Gents:
I didn't say "leading edge ribs", I said "leading edge." Lateral bracing on the leading edge tube keeps the noses of the ribs in column. Weak lateral, or little or no lateral bracing will allow the ribs to come out of column and fail. I know this by experience.
Homer Kolb did not wrap the leading edge with alum sheet, and did not recommend doing this. He felt his bow tip design and the valleys between ribs improved slow speed flight and decreased stall speed. Kolbs all use the same airfoil, all models, and have always been great slow speed performers, long before VGs. Homer's idea of flying was low and slow, right down in the tree tops to stay in touch with what was going on down there. He liked to fly with the birds. Thus the large ailerons and high lift wing.
john h
mkIII
Titus, Alabama
--
| | - The Matronics Kolb-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:
http://www.matronics.com/Navigator?Kolb-List |
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
|
| Posted: Sun Apr 09, 2017 7:55 pm Post subject: Kolb Twinstar (original version) info request |
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I don't have that problem since I have never built or flown anything but Kolbs and a few helicopters.
john h
mkIII
Titus, Alabama
--
| | - The Matronics Kolb-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:
http://www.matronics.com/Navigator?Kolb-List |
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_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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gajindra(at)sbcglobal.net
Guest
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| Posted: Mon Apr 10, 2017 8:04 am Post subject: Kolb Twinstar (original version) info request |
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take a snap punch and grind the tip down to be small enough to knock out the rivet mandrels. Then the rivets will drill straight with out enlarging the original hole
Gary Jindra
mark 111c
912ul 420 hours
From: Charlie England <ceengland7(at)gmail.com>
To: kolb-list(at)matronics.com
Sent: Sunday, April 9, 2017 5:34 PM
Subject: Kolb Twinstar (original version) info request
--> Kolb-List message posted by: Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)>
OK, now that I've got that short nose Kolb bit out of my system...
I'm now the proud owner of an N-numbered early Kolb Twinstar
(restoration project). IIRC, its serial number is in the low 20's range.
A little rusty, but we've peeled the fabric on one wing & the aluminum
seems to be in good shape, with very little corrosion, considering that
it spent its entire past life in central FL.
This one's got a Rotax 503 (converted from single to dual carbs, and to
free air cooling) that seems to be in great shape. The previous owner is
a close friend who was the builder. I trust what he tells me, and he
says that it always cooled fine running it free-air with some added
ducting.
I'll be replacing hardware, 'soft' parts, etc, but don't intend on doing
a showplane restoration; just a safe, nice flying 'after supper' flyer.
I've got the plans for the plane, but I'm hoping that you experienced
Kolbers can share any suggested mods to these early models, that will
make them safer/more durable/etc. Is there a published list of any/all
service bulletins or recommended updates? For instance, I've seen the
advice to add braces to the tailspring stinger. And I know that the
later Twinstars have mass balances on at least some of the control
surfaces; is it recommended to add them to the early models? This one
does not have any mass balances anywhere.
Who's recovered one? Any issues when you drilled out the rivets to
remove the ailerons, etc for recovering?
Any advice will be appreciated.
Thanks,
http://www.matronics.com/Navigator?Kolb-List
_=====================
http://forums.matronics.com
http://wiki.matro========================
| | - The Matronics Kolb-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:
http://www.matronics.com/Navigator?Kolb-List |
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ceengland7(at)gmail.com
Guest
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| Posted: Mon Apr 10, 2017 3:48 pm Post subject: Kolb Twinstar (original version) info request |
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|
Thanks, Gary; I've got one modified like that.
On Mon, Apr 10, 2017 at 11:01 AM, GARY JINDRA <gajindra(at)sbcglobal.net (gajindra(at)sbcglobal.net)> wrote:
| Quote: | take a snap punch and grind the tip down to be small enough to knock out the rivet mandrels. Then the rivets will drill straight with out enlarging the original hole
Gary Jindra
mark 111c
912ul 420 hours
From: Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)>
To: kolb-list(at)matronics.com (kolb-list(at)matronics.com)
Sent: Sunday, April 9, 2017 5:34 PM
Subject: Kolb Twinstar (original version) info request
--> Kolb-List message posted by: Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)>
OK, now that I've got that short nose Kolb bit out of my system....
I'm now the proud owner of an N-numbered early Kolb Twinstar
(restoration project). IIRC, its serial number is in the low 20's range.
A little rusty, but we've peeled the fabric on one wing & the aluminum
seems to be in good shape, with very little corrosion, considering that
it spent its entire past life in central FL.
This one's got a Rotax 503 (converted from single to dual carbs, and to
free air cooling) that seems to be in great shape. The previous owner is
a close friend who was the builder. I trust what he tells me, and he
says that it always cooled fine running it free-air with some added
ducting.
I'll be replacing hardware, 'soft' parts, etc, but don't intend on doing
a showplane restoration; just a safe, nice flying 'after supper' flyer.
I've got the plans for the plane, but I'm hoping that you experienced
Kolbers can share any suggested mods to these early models, that will
make them safer/more durable/etc. Is there a published list of any/all
service bulletins or recommended updates? For instance, I've seen the
advice to add braces to the tailspring stinger. And I know that the
later Twinstars have mass balances on at least some of the control
surfaces; is it recommended to add them to the early models? This one
does not have any mass balances anywhere.
Who's recovered one? Any issues when you drilled out the rivets to
remove the ailerons, etc for recovering?
Any advice will be appreciated.
Thanks,
http://www.matronics.com/Navigator?Kolb-List
_=====================
http://forums.matronics.com
http://wiki.matro========================
|
| | - The Matronics Kolb-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:
http://www.matronics.com/Navigator?Kolb-List |
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