Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
July 09, 2020, 07:16:02 AM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: [1] 2   Go Down
Print
Author Topic: Pimenoff Number 18 Build and (Short) Kit Review  (Read 1994 times)
0 Members and 1 Guest are viewing this topic.
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« on: October 10, 2014, 09:26:08 AM »

Good Gentles, All

If you have been keeping up, you know that I have been re-creating, in 3D CAD, Sandy Pimenoff's Number 18 FAI Power model from 1960. The intent was and is to make available a laser-cut "short kit", the laser cutting to be done by Bob Holman Plans service.

I have completed the initial design of the 3D CAD model, the drawing and the laser cut sheets. Mr. Holman has taken my data and created the first set of laser cut parts. I received this prototype set yesterday in the mail, and anxiously opened the box. For those of you who have had the pleasure of building from a Bob Holman kit, you know that Mr. Holman does outstanding work. The wood he uses is top notch, and the weights and grains are perfect for the intended use. The laser cutting is as clean as you can get, and once the three 1/8 inch tabs are cut, the parts fall out of the sheets.

A few words about the design itself:

When creating the 3D CAD model, my intent was to stay as historically accurate as possible. I used three sources for the model: 1) From the Zaic Yearbook, 2) An image from Volar Libremente (both of which can be found with a simple Google Images search)  and 3) A scanned image provided by Tapio, as seen in an earlier post. I felt that the image supplid by Tapio to be the most accurate, as it was from a (Finnish) modeling book, and the article itself was written by Mr. Pimenoff himself. However, the plan shown from the book, though complete, did not have many dimensions, so I had to rely on the other two sources. I also felt that the Volar Libremente drawing was more accurate than the Zaic.

I feel that I have created a very historically accurate model, and drawing. I did take a couple of liberties, but they are minor, and in no way changes the aerodynamic properties (One example is that at the wing outer panel dihedral break, it was difficult to see exactly how Mr. Pimenoff strengthened the joining of the main and outer panel. From the Image from Tapio, it appears that there is a doubler at the leading and trailing edge. I decided that to incorporate two 1/16th ply doublers on the spar instead)

A note about the measuring units: The airplane was created in Metric units, so when I created the 3D model, I also used Metric. So all of the outlines, and basic dimensions are correct per the original. However... when it cam time to create the cutouts for the spars, leading and trailing edges, the thicknesses of the material, Mr. Holman and I agreed to use Inch units. For instance, the main spar is shown as "5 X 10 Pine". In the model, and the drawing, I used 3/16 X 3/8. For the spars in the horizontal stab, the original was "3 X 3" I used 1/8 X 1/8. And so on. But be assured that the over all dimensions are in Metric.

The first image is of the completed 3D CAD model. the second picture is of the two bags of laser cut parts.

The drawing (plan): Some of you may have noticed that the drawing that I up-loaded to the Plans Gallery has been removed. There are two main reasons for this:

1) That drawing was done many years ago (by me) and when I started to research this present model, I saw that there were several serious (historic) errors on that drawing.

2) Because the laser short kit and the drawing will now be offered commercially by Bob Holman, I did not feel that it would be right to have the drawing offered as a download.

So, now on to the build itself.

Last night, I laid out the drawing for the rudder and horizontal stab. I first glued the rudder and stab center rib together. The next couple of pictures show the laser cut sheets, the rudder completed and the rudder/stab center rib in place on the drawing.

One of the first things you will notice is that the three 1/8 X 1/8 spars are embedded in the ribs. Due to the laser cutting, this becomes very easy to do. If I had to cut the spar holes by hand, I would not have used this technique. However, the cutting is so good that the 1/8 spars slid effortlessly through the holes. I first marked cut the three spars to the correct length, then marked the spars where the center rib would be. I then slid the spars through the center ribs, placed the center rib, rudder into the correct location. Once located, I used thin Ca to glue them in place. Then working outward, I slid each rib down the spars, located them and then glued them in place. The entire stab took about 45 minutes to complete.

The laser cutting makes me feel like I'm cheating (almost).
Attached files Thumbnail(s):
Pimenoff Number 18 Build and (Short) Kit Review
Pimenoff Number 18 Build and (Short) Kit Review
Pimenoff Number 18 Build and (Short) Kit Review
Pimenoff Number 18 Build and (Short) Kit Review
Pimenoff Number 18 Build and (Short) Kit Review
Pimenoff Number 18 Build and (Short) Kit Review
Logged

"We have done the impossible, and that makes us mighty..."
billdennis747
Palladium Member
********

Kudos: 62
Offline Offline

United Kingdom United Kingdom

Posts: 4,101



Ignore
« Reply #1 on: October 10, 2014, 01:39:55 PM »

This looks fabulous. A pity my efforts in power duration produced only holes in the ground. But I'm tempted. What engine was in the original? I now only have an ED Racer of 2.5cc size. What is its reputation for trimming?
Logged
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #2 on: October 10, 2014, 01:53:42 PM »

I'd guess the ED would be near perfect for this airplane. The original was flown with an ETA .15 and later with a tuned Oliver Tiger. I'm going to build two, one with a PAW .15 (2.5) and one with electric.

According to the documentation, Mr. Pimenoff brought the airplane to the 1960 FAI World Championships un-tested, trimmed it the morning of the contest and flew it all day. So I'm thinking it might be a pretty easy one to trim. Someone else (on another thread) mentioned that they didn't think it even needed the auto-rudder.
Logged

"We have done the impossible, and that makes us mighty..."
billdennis747
Palladium Member
********

Kudos: 62
Offline Offline

United Kingdom United Kingdom

Posts: 4,101



Ignore
« Reply #3 on: October 10, 2014, 02:26:48 PM »

I wonder why the fin was left empty of structure? Is that a good idea?!
Logged
Ployd
Gold Member
*****

Kudos: 19
Offline Offline

Australia Australia

Posts: 300




Ignore
« Reply #4 on: October 10, 2014, 07:18:22 PM »

What sort of mula, pesos, denarii are we talking for the short kit and plan?

Ployd in OZ
Logged

"So I collect engines, what's your problem?"
Tapio Linkosalo
Platinum Member
******

Kudos: 30
Offline Offline

Finland Finland

Posts: 1,237



Ignore
« Reply #5 on: October 11, 2014, 04:24:00 PM »

May I copy the pictures (and description) to a Finnish modeling forum?

Logged
duration
Gold Member
*****

Kudos: 8
Offline Offline

United States United States

Posts: 488



Ignore
« Reply #6 on: October 11, 2014, 05:40:23 PM »

Took a look at the three-views of the model in the 59-61 Zaic Year Book and the upper rudder parts (wide leading edge, trailing edge, and spar) are shown as dashed lines. This would imply that the rudder is sheeted. The lower rudder is shown as a solid balsa piece (i.e. with Frank's signature wood grain). On the wing and stab, ribs are rendered as solid lines, indicating the surfaces are tissue or silk covered.

I can't imagine the upper rudder being stiff enough without sheeting on both sides.

Louis
Logged
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #7 on: October 11, 2014, 08:18:52 PM »

May I copy the pictures (and description) to a Finnish modeling forum?

Hi Tapio

Yes, absolutely. In fact, if there are any glaring errors, please let me know, as this is the prototype and I can still make changes.

billdennis:

To quote Tapio from the earlier thread/post:

"About rudder, the article (from the book) says that "the rudder should be built-up instead of sheet, to avoid warping.""

Ployd:

I don't know the final cost yet. I should know by the end of next week. I can say, though, that even though this is a "short" kit, it is almost a complete kit. The airplane will be able to be completed with three 1/8 X 1/8 X 36, one sheet of 3/16 one sheet of 3/32 one sheet of 1/4 and a little 1/6th ply (and a little 1/8 ply or 3/8 X 3/16 Hardwood, depending on how you do the firewall/motor mount)



Logged

"We have done the impossible, and that makes us mighty..."
JohnOSullivan
Silver Member
****

Kudos: 4
Offline Offline

Canada Canada

Posts: 205


WWW

Ignore
« Reply #8 on: October 11, 2014, 08:49:01 PM »

Also, the Zaic Yearbook shows the tailplane spars flush with the surface rather than internal.
Logged

John O'Sullivan
MAAC 5401
MACI 26
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #9 on: October 11, 2014, 09:05:39 PM »

Also, the Zaic Yearbook shows the tailplane spars flush with the surface rather than internal.

Which conflicts with both the Book and Volar Libremente plan. In this case, I believe the Zaic plan was/is incorrect.
Logged

"We have done the impossible, and that makes us mighty..."
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 866




Ignore
« Reply #10 on: October 11, 2014, 10:57:54 PM »

Bill Dennis' point is that there is nothing in the fin structure other than outline.
It obviously worked but it doesn't seem like great design (to me). It obviously wasn't a weight issue, look at all the wood in the tail (h.stab).

Bill, an ED Racer would be a decent choice, but this model will handle more power.

This is a good thread, Iceman, keep up the good work!

JB
Logged

Gliders are a part of me.
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #11 on: October 13, 2014, 02:06:50 PM »

The Stab/Rudder is complete. One thing I did find was to make sure to glue int the stab tip filler and the two gussets at the tip before trying to lift the stab off the plan or trying to sand.
Attached files Thumbnail(s):
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Logged

"We have done the impossible, and that makes us mighty..."
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #12 on: October 13, 2014, 02:12:08 PM »

Now on to the wing. As you can see in the pictures, I actually made a mistake and glued the dihedral braces on the spar before I slid the ribs down the spar. I had to remove one set, slide the ribs on and then glued the braces back on. I also decided to use a hard balsa spar instead of  a "Pine" spar.

As before, the laser cut ribs fit perfectly.
Attached files Thumbnail(s):
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Logged

"We have done the impossible, and that makes us mighty..."
FF Bruce
Gold Member
*****

Kudos: 13
Offline Offline

United States United States

Posts: 486



Ignore
« Reply #13 on: October 13, 2014, 03:53:04 PM »

Are you flying this in Vintage FAI ? If so a Super Tigre G20 from 1960 would really make it go.Of corase it would need to weigh 26.5 oz. and as it looks it would come out way under weight.Nice model
Logged
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #14 on: October 14, 2014, 08:34:07 AM »

Are you flying this in Vintage FAI ? If so a Super Tigre G20 from 1960 would really make it go.Of corase it would need to weigh 26.5 oz. and as it looks it would come out way under weight.Nice model

Hi Bruce, thanks. The airplane is going together quite well. Mr. Pimenoff designed a very nice airplane. I can't wait to start flight-testing it.

As for flying it in Vintage FAI, I would love to, but that event is not flown anywhere near me (The North East US). I am planning on flying it in AMA Electric B. Not sure what other event.

Attached are a few more pictures of the wing build. I put the tip panel together last evening, and everything fit exactly as it should. I first placed the trailing edge (laser cut) on the plan. (BTW - I've forgotten to mention that for both the stab and the wing trailing edges, since I am building on a flat surface, I added a 1/16th shim under the forward edge of the trailing edge in order to maintain the under camber)For the spar and ribs, I first marked the laser-cut tapered spar where the ribs would be placed, then slid the ribs down the spar. Then I glued in the first rib, then the second and so on.

The tip panel went together quite well.
Attached files Thumbnail(s):
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Logged

"We have done the impossible, and that makes us mighty..."
flydean1
Platinum Member
******

Kudos: 25
Offline Offline

United States United States

Posts: 1,110



Ignore
« Reply #15 on: October 14, 2014, 10:04:15 AM »

In addition to Vintage FAI Power, for Nostalgia Gas, it would go really well with an OS MAX or a Veco .19, especially one suitably massaged by Bob Mattes.
Logged
Red Buzzard
Silver Member
****

Kudos: 4
Offline Offline

United States United States

Posts: 127



Ignore
« Reply #16 on: October 14, 2014, 11:09:29 AM »

Hi Dean,

Again there is some confusion about Vint FAI and Nos Gas. Vint FAI goes on into the early modern years while Nos Gas stops in Dec. 1956. The Pimenoff #18 is essentially a 1960 or thereabouts model. Ineligible for Nos Gas but perfect for Vint FAI. Unfortunately a one-trick pony unless you want to fly it in AMA Gas. Before you cut wood, it is good to think about which Vintage era you are aiming for, which engine is appropriate, etc. As Bruce points out the ST G20 is dynamite for V-3, but may not be appropriate for other Vintage eras. Likewise #18 fits V-3 but can't fly in V-1 or V-2 because it is too "young".

If you want something Finnish from the Nos era, try Zaic 1957 - 58, page 51. There is a small group of four models that flew in 1956, one of which is by "Samdy" and is presumed to be Sandy Pimenoff. Nice proportions, the right era to do double duty, etc. One of the others, the Love Me or Leave Me, is being campaigned successfully by a good friend in both events.

Bill
Logged
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #17 on: October 21, 2014, 08:11:12 AM »

Hi all

Just an update: The wing and tail are complete for the Number 18. They both came out very well. The only problem is that the elliptical tips on the stab are pretty fragile. I wonder if this had something to do with why Mr. Pimenoff went with a rectangular plan-form later for the stab?

As some of you might be aware, I do not have anywhere to do dope-and-tissue (or silk), so I am covering the wings and stab with Ultracote Parklite. I know that plastic coverings do not add the rigidity that tissue and silk do, but I really don't have any choice. I think the wing is rigid enough and will not present any problems, but I am a little worried about the stab.

I covered the stab/rudder last night, and it looks pretty good. Certainly not dope and tissue good, but man, do I love those elliptical surfaces!

Next up is to build the fuselage. Should be very straight-forward. I'll post pictures later.

If all go to plan, I should be able to put up a few test flights on the electric version before the snow flies. I'm still trying to figure out the engine for the diesel version. I had found a vintage Oliver Tigre on EBay, and as much as I hate ebay, I did put a bid on it, but it finally went up to $265.00. Too rich for my blood.
Logged

"We have done the impossible, and that makes us mighty..."
Ployd
Gold Member
*****

Kudos: 19
Offline Offline

Australia Australia

Posts: 300




Ignore
« Reply #18 on: October 21, 2014, 07:08:17 PM »

Quote
I had found a vintage Oliver Tigre on EBay, and as much as I hate ebay, I did put a bid on it, but it finally went up to $265.00. Too rich for my blood.

You can buy brand new one's direct from England (Tom Riley) for about 160 pounds sterling (from memory).

Ployd in OZ
Logged

"So I collect engines, what's your problem?"
glidermaster
Gold Member
*****

Kudos: 19
Offline Offline

Canada Canada

Posts: 866




Ignore
« Reply #19 on: October 22, 2014, 10:55:19 AM »

Ployd's almost right - see link below.

CS Replica's might also be an option. Beware, however, the legendary Oliver quality is not fully replicated  Wink

http://controlline.org.uk/phpBB2/viewtopic.php?t=4251&postdays=0&postorder=asc&&start=180

John
Logged

Gliders are a part of me.
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #20 on: November 04, 2014, 08:08:14 PM »

Ok, Guys, I'm back...

I've put the fuselage together. Very straight-forward, but I'll post a few pictures:

1) The Wing Pylon and Fin are laser cut and come in the short kit
2) I measure and mark where the top stringer is placed
3) The top stringer is placed
4) the hardwood engine mounts and three uprights are glued on the pylon
5) the other side is marked
6) The stringers are glued on
Attached files Thumbnail(s):
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Logged

"We have done the impossible, and that makes us mighty..."
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #21 on: November 04, 2014, 08:23:12 PM »

1) The fuselage sides, top and bottom are not included in the short kit, but the dimensions are shown on the drawing. All four can be easily cut from one sheet of 'A' grain 1/8 and one sheet of 3/32.
2) The assembled pylon is glued into the slot in the fuselage bottom.
3)  The bulkheads (included in the kit) are glued onto the bottom, then the sides are glued on. (Hint: This is very tricky to do with super glue, use a slow-cure glue (Titebond, etc))
4) A close up of the rear slot where the fin will be inserted (This is another place where you do not want to use super glues!)
5) The top is glued on.
Attached files Thumbnail(s):
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Logged

"We have done the impossible, and that makes us mighty..."
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #22 on: November 04, 2014, 08:46:50 PM »

1) The fuselage
2) Detail of the fin
3) Detail of the pylon
4) Complete wing (With messy bench!)
Attached files Thumbnail(s):
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Re: Pimenoff Number 18 Build and (Short) Kit Review
Logged

"We have done the impossible, and that makes us mighty..."
billdennis747
Palladium Member
********

Kudos: 62
Offline Offline

United Kingdom United Kingdom

Posts: 4,101



Ignore
« Reply #23 on: November 05, 2014, 04:24:24 AM »

I´m enjoying following this. On the rare occasions when I´ve tackled something similar, I found it very hard to cut straight sides or tops. A lot of balsa sheets seem to have inbuilt stresses which come out when you strip it. I had to resort to cutting oversize, leaving it a while and cutting again. And maybe again.
Do those bearers come with the kit and are they adequately hard? They look much paler than the beech we get in the UK
Bill
Logged
Starduster
Platinum Member
******

Kudos: 35
Offline Offline

United States United States

Posts: 1,396


Topic starter


Ignore
« Reply #24 on: November 05, 2014, 04:48:05 PM »

Hi Bill

The "Bearers" are Bass wood. Spruce is hard to find around here, and I think the bass will be fine. And, no, they are not included in the kit.

Rich (who is still looking for a diesel for this airplane)
Logged

"We have done the impossible, and that makes us mighty..."
Pages: [1] 2   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!