KR> RE: tri-gear conversion

[Joe Beyer]

Message: 1
List-Post: krnet@list.krnet.org
Date: Wed, 2 Nov 2011 00:00:47 -0700 (PDT)
From: velocityo...@yahoo.com
Subject: Re: KR> Continuing thoughts on tri-gear conversion
To: KRnet 
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<1320217247.32437.yahoomail...@web126104.mail.ne1.yahoo.com>
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>Hello Dave,
 
>First off my salute to you and sincere thanks for your service to this
>country! You have my respect and help at any time.
 
>Glad to see you planning to get this thing going. A couple of things to go
>over. The original spring-bar isn't what is used for the tri gear
>conversion

I used the spring bar sawed in half and tapered for my tri gear conversion.
I made a trailing link gear leg which has taken some pretty bouncy landings.
The biggest challenge was getting the nose wheel to not shimmy or bend at
the pivot point. 
Joe
Valley View (Estacada)

KR> Re: Tri-gear Conversion

[Lee Parker]

I changed the small 4" tail wheel on my KR to a larger 6" tail wheel (solid 
rubber). . That makes the tail wheel farther back a few inches.  It now sits 
about 3 1/2" higher which makes it easier to see over the nose.  I know the 
math doesn't add up but, the new tail wheel I installed I made from a hospital 
stretcher and it sits higher.  The Tractor Supply cap bearing will fit right 
into the holes and a 1/4" will fit the bearings.  It also makes it easier to 
land and roll out is a lot easier to control.. I am not as likely to ground 
loop it now.  I takes a little more room to turn it around but, at least I can 
land it now without ground looping it. I am a 2000 hr. pilot but learning to 
fly a KR is a lot different but I have found that the more you play with it the 
more you learn..  Tail wheels are a whole different ball game.  I now have 10 
hours on it and still working out the bugs.




From: smwood <smw...@md.metrocast.net>
To: kr...@mylist.net
Sent: Wednesday, November 2, 2011 10:13 AM
Subject: KR> Re: Tri-gear Conversion

Dave,
I converted N6242 from a conventional retract gear to fixed tri-gear using 
Diehl fixed mains and nose gear.  The large holes in the wing in front of 
the spar were converted to inspection panels; very useful.  The large holes 
aft of the spar were mostly closed in with foam and glass lay-up.  You are 
correct: After fill, sanding and paint, the cover up is invisible.
If you use the RR spring gear, the RR gear legs may be to short to match the 
nose gear height and steering geometry.  The RR spring bar would need to be 
absolutely latched in the down and locked position; you may not have room 
under the seat for that setup.  The RR gear legs are HUGE flat plates 
hanging out in the air stream; sort of a speed brake permanently deployed. 
You will have much difficulty fairing around those wiggly gear legs.  On 
most retract KR-2 there is an aileron control cable running through the area 
aft of the main spar.  You will need to re-route the cable or use more 
modern control linkages.  If you have a spring bar aft of the spar, where 
are you going to mount the stick?

Highly recommend you use the Diehl or similar fixed main gear.  Fairings are 
also available.

Sid Wood
Tri-gear KR-2 N6242
Mechanicsville, MD, USA
smw...@md.metrocast.net

--
The aircraft was issued it's N-Number (N86KR) in 1986, and is in need of
3 things, it seems - wing pins, some avionics replacement, and
conversion to tri-gear (personal preference).

The pins can be bought from NVAero from what I understand, I've got the
avionics I plan to install back home - those are the 'easy' jobs..

The tri-gear conversion seems the most difficult, and has been the
subject of much thought & online research, resulting in the following
plan (which I'm seeking comments/advice on)

1) Components would be the original KR2 spring-bar mains, and the Diehl
nose gear kit as sold by NVAero.

2) The 'objective' is to convert the plane from taildragger to tri-gear
'in-place', prior to ferrying it from where it is now to my home state.

3) From what I've read here and online, the largest block of time (and
largest requirement for jigs/tools/space/etc) in doing this work is the
post-conversion re-assembly - which generally is done by flipping the
plane and re-glassing the area cut open to gain access to the spar/gear.

What I have come up with, is a *possible* process to accomplish this
conversion without flipping the plane, by raising it up on jacks,
cutting away a rectangular patch of skin (and saving it in-tact for
later) to create access to the mains. At this point, the gear could be
'flipped' from the front of the spar to the back, and then the
rectangular patch would be re-attached with doublers around the edges
(inside the stub wings, not out in the airstream) and Hysol 9309.3
(microbead structural adhesive) for an adhesive and gap filler. Properly
done (eg, keeping the patch sucked up tight to the plane while the Hysol
cures) it should be just about as strong as the original structure, and
once sanded & painted, invisible...

Now, I'm not familliar with the specifics of the KR2 design yet (this is
a mix of army helo repair techniques, online research, and so on),
beyond what I can read online. Apart from a small bit of added weight
(from 4 doubler strips and the 9309), do you guys see any issues with
this plan? Is it going to create issues with the structure of the
stub-wings? Am I going to have trouble cutting out the 'access patch'
and separating the glass skin from the rest of the structure (Say, due
to the skin being adhered to foam & wood structure, making intact
removal of a cut-out section impossible)

I'm submitting this for comment, because you guys know alot more about
these planes than I do at this point... For all I know, there is a very
good reason why everyone flips t

KR> Re: Tri-gear Conversion

[smwood]

Dave,
I converted N6242 from a conventional retract gear to fixed tri-gear using 
Diehl fixed mains and nose gear.  The large holes in the wing in front of 
the spar were converted to inspection panels; very useful.  The large holes 
aft of the spar were mostly closed in with foam and glass lay-up.  You are 
correct: After fill, sanding and paint, the cover up is invisible.
If you use the RR spring gear, the RR gear legs may be to short to match the 
nose gear height and steering geometry.  The RR spring bar would need to be 
absolutely latched in the down and locked position; you may not have room 
under the seat for that setup.  The RR gear legs are HUGE flat plates 
hanging out in the air stream; sort of a speed brake permanently deployed. 
You will have much difficulty fairing around those wiggly gear legs.  On 
most retract KR-2 there is an aileron control cable running through the area 
aft of the main spar.  You will need to re-route the cable or use more 
modern control linkages.  If you have a spring bar aft of the spar, where 
are you going to mount the stick?

Highly recommend you use the Diehl or similar fixed main gear.  Fairings are 
also available.

Sid Wood
Tri-gear KR-2 N6242
Mechanicsville, MD, USA
smw...@md.metrocast.net

--
The aircraft was issued it's N-Number (N86KR) in 1986, and is in need of
3 things, it seems - wing pins, some avionics replacement, and
conversion to tri-gear (personal preference).

The pins can be bought from NVAero from what I understand, I've got the
avionics I plan to install back home - those are the 'easy' jobs..

The tri-gear conversion seems the most difficult, and has been the
subject of much thought & online research, resulting in the following
plan (which I'm seeking comments/advice on)

1) Components would be the original KR2 spring-bar mains, and the Diehl
nose gear kit as sold by NVAero.

2) The 'objective' is to convert the plane from taildragger to tri-gear
'in-place', prior to ferrying it from where it is now to my home state.

3) From what I've read here and online, the largest block of time (and
largest requirement for jigs/tools/space/etc) in doing this work is the
post-conversion re-assembly - which generally is done by flipping the
plane and re-glassing the area cut open to gain access to the spar/gear.

What I have come up with, is a *possible* process to accomplish this
conversion without flipping the plane, by raising it up on jacks,
cutting away a rectangular patch of skin (and saving it in-tact for
later) to create access to the mains. At this point, the gear could be
'flipped' from the front of the spar to the back, and then the
rectangular patch would be re-attached with doublers around the edges
(inside the stub wings, not out in the airstream) and Hysol 9309.3
(microbead structural adhesive) for an adhesive and gap filler. Properly
done (eg, keeping the patch sucked up tight to the plane while the Hysol
cures) it should be just about as strong as the original structure, and
once sanded & painted, invisible...

Now, I'm not familliar with the specifics of the KR2 design yet (this is
a mix of army helo repair techniques, online research, and so on),
beyond what I can read online. Apart from a small bit of added weight
(from 4 doubler strips and the 9309), do you guys see any issues with
this plan? Is it going to create issues with the structure of the
stub-wings? Am I going to have trouble cutting out the 'access patch'
and separating the glass skin from the rest of the structure (Say, due
to the skin being adhered to foam & wood structure, making intact
removal of a cut-out section impossible)

I'm submitting this for comment, because you guys know alot more about
these planes than I do at this point... For all I know, there is a very
good reason why everyone flips the plane & does it the 'conventional'
way - or maybe it's just that's the way that always comes to mind... I
just started from 'assume you cannot flip the bird, what would you do to
fix a hole in the bottom (that conveniently happens to expose the spar &
landing gear)...