SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Dec 09, 2011, 12:23 PM
Registered User
Jeff in So Cal's Avatar
Torrance, CA
Joined Sep 2004
385 Posts
Build Log
Martin K-III Kitten, Peter Rake Prototype

The J. V. Martin Kitten was designed and built in 1917-18 as a lightweight airship interceptor. The development of this aircraft did not support flight evaluations to occur in time for modifications to be made that might have made this plane a viable interceptor. Unfortunately, Mr. Martin did not appear to be receptive to constructive criticism that might have helped in creating a more flight worthy airplane (this was a flaw that followed him throughout his limited aircraft design career).

Regardless, long range bombers made the airship obsolete and a new generation of interceptors were required to combat the threat.

The Kitten is a small airframe, wingspan under 20 feet and a length slightly over 13. The plane exceeded empty weight predictions and the 45 h.p. Gnat A.B.C. appears to have been inadequate based on the few available flight reports.

The Kitten exhibited a few design features which were patented: semi-retractable landing gear, K-Struts and a tail skid that was integral to the rudder with some sort of bungee for shock absorption.

Getting back to the flight reports. The plane does not appear to have been flown more than ten feet off the ground and in a straight line. The ailerons did not appear to be very responsive. The plane also appeared to be somewhat unstable in pitch which was exacerbated by attempting to retract the landing gear which would shift the cg further aft.

Sounds like a great RC subject doesn't it?
Jeff in So Cal is offline Find More Posts by Jeff in So Cal
Last edited by Jeff in So Cal; Jan 27, 2012 at 11:41 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 09, 2011, 12:42 PM
Registered User
Jeff in So Cal's Avatar
Torrance, CA
Joined Sep 2004
385 Posts
Martin Kitten

As you can see from the photo's in the initial post, I won't have to worry about selecting from a wide range of livery. There was only one prototype developed. The Kitten is in the possession of the Smithsonian, I wish their were more detailed photo's available.

The landing gear partially retracts. The Ackerman light weight spring wheels nest in fairings which leave about one-half of the wheel exposed. The undercarriage appears to be rectangular stock which nestled into a cavity in the bottom of the fuselage. The only documentation I have been able to find indicates that a hand crank driving a worm gear retracted the gear. This was supposedly very easy to operate. If any one has additional detail, I would be grateful if you would share. I will most likely model fixed gear with accommodations for adding retracts later.

The ailerons are outboard of the upper wing. They are driven by an internal torque rod which Peter has included in the design. I can not tell from the photo's how the control cables were brought down from the upper wing. Once again, if anyone has any documentation, I would appreciate it. Otherwise, I will ad-lib.
Jeff in So Cal is offline Find More Posts by Jeff in So Cal
Last edited by Jeff in So Cal; Dec 09, 2011 at 02:33 PM.
Reply With Quote
Old Dec 09, 2011, 02:41 PM
Registered User
Jeff in So Cal's Avatar
Torrance, CA
Joined Sep 2004
385 Posts
Plans and Parts

I have had the plans printed and the laser cut parts arrived from Monzano. I need to get the few details I mentioned previously worked out before I start the build. I really don't want to work myself into a corner.

The engine compartment is very short coupled providing a small moment arm. I believe I am going to need to get the battery and speed control forward of the firewall to achieve balance.

Jeff
Jeff in So Cal is offline Find More Posts by Jeff in So Cal
Reply With Quote
Old Dec 09, 2011, 02:52 PM
Registered User
USA, CA,
Joined May 2001
1,724 Posts
Hi Jeff,
I like that little Airplane what Scale is it? Yes for sure it Sounds like a great RC subject to build What is the wingspan? Where did you get the plans? Hope to see the kit at Manzano Laser Works Soon ?
Joe Pierson is offline Find More Posts by Joe Pierson
Last edited by Joe Pierson; Dec 09, 2011 at 03:01 PM. Reason: Added text
Reply With Quote
Old Dec 09, 2011, 05:11 PM
Registered User
Norfolk, England
Joined Sep 2001
7,720 Posts
Jeff,
When I drew this one, I visualised it with a fixed u/c and primarily 3+1 function control - 3 channel, with the 'ailerons' as an auxiliary function.
To be scale, the u/c shouldn't really be any more than half retracted, because that's as much as they did in the official trials - otherwise it altered the c/g so much it became downright dangerous. That being so, it's unlikely that it ever flew with it fully retracted, no matter what Mr. Martin claimed for it.
Strictly speaking, the nose isn't really that short for the period. Just for comparison with another close coupled type, the Albatros DXI has virtually the same fuselage lengths ahead of and behind the balance point. If anything, the Martin has the longer nose of the two by a 1/4", but the shorter tail by 0.7". However, the Kitten is 48.5" span over the 'ailerons', whereas the DXI spans 52.5". IIRC, the DXI is 1/6 scale and the Kitten 1/5 scale.

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Old Dec 09, 2011, 05:15 PM
Registered User
Norfolk, England
Joined Sep 2001
7,720 Posts
Joe,
Assuming it actually flies, Manzano will list the kit just as soon as Jeff test flies his model. So, not likely to be within the next week or so.

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Old Dec 10, 2011, 12:27 PM
Registered User
Jeff in So Cal's Avatar
Torrance, CA
Joined Sep 2004
385 Posts
Martin Kitten

Quote:
Originally Posted by PETERRAKE View Post
Joe,
Assuming it actually flies, Manzano will list the kit just as soon as Jeff test flies his model. So, not likely to be within the next week or so.

Pete
Assuming it flies......................., which explains my comment about this being an interesting RC subject. To take the effort to build a scale model of an airframe that had inherent design problems requires a somewhat (fill in the blank) individual.

I am on company travel for the next week, so serious building won't start until I return home on Friday. S, Peter's assessment of not being ready to maiden for a week or two is a fair bet.

The picture shows either a giant of a man or a rather small airplane with landing gear retracted.

Jeff
Jeff in So Cal is offline Find More Posts by Jeff in So Cal
Reply With Quote
Old Dec 10, 2011, 02:34 PM
a.k.a Maltone
Australia, NSW, Goulburn
Joined Jan 2005
6,858 Posts
A typical Rakian subject an interesting one - go Jeff!

Pat
Pat Lynch is online now Find More Posts by Pat Lynch
RCG Plus Member
Latest blog entry: A Small Diversion From Annie
Reply With Quote
Old Dec 10, 2011, 03:00 PM
Registered User
Jeff in So Cal's Avatar
Torrance, CA
Joined Sep 2004
385 Posts
Rakian?

Quote:
Originally Posted by maltone View Post
A typical Rakian subject an interesting one - go Jeff!

Pat
Had to look Rakian up: Rakia (also Rakija or Rachiu) is an alcoholic beverage that is produced by distillation of fermented fruit; it is a popular beverage throughout the Balkans. Its alcohol content is normally 40% ABV, but home-produced rakia can be stronger (typically 50% to 60%).

This guy could probably help maintain one's focus during building.
Jeff in So Cal is offline Find More Posts by Jeff in So Cal
Reply With Quote
Old Dec 10, 2011, 04:20 PM
Registered User
Norfolk, England
Joined Sep 2001
7,720 Posts
Somehow, I don't think that's quite what Pat had in mind - although you never know.

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Old Dec 10, 2011, 04:40 PM
Registered User
Jeff in So Cal's Avatar
Torrance, CA
Joined Sep 2004
385 Posts
Rakian

Quote:
Originally Posted by PETERRAKE View Post
Somehow, I don't think that's quite what Pat had in mind - although you never know.

Pete
Definitely not, but I love the picture of the home distillery. That ole boy may have flown the Kitten from the looks of him.

Jeff
Jeff in So Cal is offline Find More Posts by Jeff in So Cal
Last edited by Jeff in So Cal; Dec 10, 2011 at 05:07 PM.
Reply With Quote
Old Dec 10, 2011, 06:08 PM
Registered User
Jeff in So Cal's Avatar
Torrance, CA
Joined Sep 2004
385 Posts
Fuselage outer surface

In reviewing the limited documentation available, it is difficult to tell if the fuselage was sealed wood or ???? The enlarged photo below shows a very irregular pattern on the fuselage which is quite similar to the wings in color, pattern and aging.

Peter,

Were you intending a doped 1/16 inch balsa skin?

Jeff
Jeff in So Cal is offline Find More Posts by Jeff in So Cal
Reply With Quote
Old Dec 10, 2011, 09:00 PM
You sabotaged my plane.
eliworm's Avatar
Arizona
Joined Jun 2002
2,806 Posts
I had posted this info in the other Kitten thread but should be useful here as well. These are some pages from the "Textbook of Applied Aeronautic Engineering" published in January of 1920 that everyone may find interesting.

Jim
eliworm is offline Find More Posts by eliworm
Reply With Quote
Old Dec 11, 2011, 02:51 AM
Registered User
Norfolk, England
Joined Sep 2001
7,720 Posts
Jeff,
I had nothing particular in mind for the finish, the sheet is there just to emulate the ply skinned original. I'm not terribly keen on exposed balsa finishes, it just never looks right to my mind. Knowing me, I'd probably cover the fuselage and then paint on the wood grain effect. However, if you feel it might be fabric covered, that solves the problem entirely. If only some enterprising person would start making 1/32 liteply our stained fuselage problems would be over.

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Old Dec 11, 2011, 03:50 AM
Registered User
Norfolk, England
Joined Sep 2001
7,720 Posts
Jim,
Interesting stuff there, especially the bit about no exposed aileron linkages. The model was always going to be a compromise in that respect, but I can't recall why I didn't show the internal elevator linkage. I usually do, but possibly went for simplicity on this one - another compromise. Jeff is at liberty to go internal if he so desires.
I saw no mention of a ply skinned fuselage, but that strip along the side has to be there for a reason. I assumed it was to cover a join.
Interesting that, withought really trying, I came pretty close to a scale fuselage structure.
As regards the ineffectiveness of the ailerons, I did alter them slightly. Figuring that they might be a little better if the rear part moved a little more (that being the part closest to where real ailerons would be), I moved the pivot a little forward.

The one point that did become obvious is that the item appeared to have been based on the designers own notes. It quoted all the inovations, and how effective they were supposed to be, but failed to mention that most of them didn't actually work very well. The retracting u/c couldn't be used in flight because of balance issues, the K struts were deemed too flimsy in the official test reports and the ailerons were ineffective. Goodness knows how they determined it would fly 22 miles on a gallon of petrol, I doubt it ever flew one mile, never mind 22. Especially so with an ABC Gnat fitted.

Why would I possibly want to draw up such an unlikely model? There's just something about it that appeals to me. It's quite attractive in an ungainly sort of way. However, although the plan shows scale dihedral (none), I wouldn't complain if Jeff wanted to add some - make it a real 3 channel style model. Then it wouldn't matter if the ailerons didn't work at all. Personally, I think they'll work well enough but Jeff is the one building it.

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log Peter Rake's 60" Pfalz E.1 - 3rd Prototype, yes another one... 1905Flyer3 Scale Kit/Scratch Built 40 Nov 30, 2011 02:04 AM
Build Log Peter Rake's 60" Pfalz E.1 - 2nd Prototype Newtron Scale Kit/Scratch Built 64 Oct 12, 2011 10:13 PM
Discussion Peter Rake's 'Martin Kitten' Neil Straker Scale Kit/Scratch Built 30 May 27, 2010 04:24 PM
Peter Rake 50" Camel prototype wanted Bengtson Scale Kit/Scratch Built 8 May 28, 2003 11:36 PM