Sandy Pimenoff's Number 18

[Tapio Linkosalo]

The drawing does not indicate the angles, but the attached picture suggest the angles, and the article says "the decalage should be 2 to 3 degrees as in picture 54, the final value is established during trimming."

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

To me it seems that the spars are inset into the ribs, and the riblets have a flange coming over the spar.


 

[mick66]

Hi

looking at my trimming notes ... all angles wrt bottom of fuse.

CG:                         83%
LeftThrust:             +1.5 degrees
DownThrust:           +2.0 degrees (as in down)
Wings:                    +3.0 degrees
Tail:                        +1.5 degrees (giving +1.5 decalage)
PRT tip washout:       +2mm
PRT inner panel:        flat
STB panel washin:    +2mm
STB tip washout:      +2mm

On the actual plan the rigging angles are Wing (+4 degrees) and Tail (+2 degrees).
I've trimmed it out at little under ... +1.5 degrees as noted above.

Tip washout measured at TE behind last rib.

Cheers

Mike

[Starduster]

Gentlemen:

Thanks for all the help.

Thanks also to the power of "parametric" 3D modeling, it took me all of about 5 minutes to change the diagonals, see attached.

[hastf1b]

Sandy Pimenoff with "Ascender".

Heinz

[Tapio Linkosalo]

Different tailplane!

[john thompson]

Zaic 59/61 , shows 2 versions No; 18 and the Ascender , 18 had rectangler tailplane .
My set up is 82 % cg ,+3.8 wing +2.3 tail . 4 down 1.5 left  ( these are approximate but as measured with a digital gadget ) . No warps except both tips washout by about 1.5 . Power Oliver Tigre replica 9x 5 Master about 12 k . Model flies beautifully, nice spiral, A/R not really needed . Dihedral is on low side for windy UK weather .
I have tried with more power without success ,( the problem I believe,  lies with the wing section having the undercamber starting immediately from the LE ) the model being extremely erratic in pattern and unreliable . I have built another wing with this section for another model and had same erratic pattern . On other models where this apparent problem has arisen , I have covered in the bottom of wing to make a flat bottomed section and the problem has gone away . So I must, with this limited testing assume that the undercamber was the problem , but with so many variables who knows ?
On page 47 of that Zaic is also shown, what I think is a rather good model !!
 All ready for the 2 days at Middle Wallop . Forecast fine Sunday, but rain Monday . At least I will (with others ) not be stuck on the gate this time, as we are not charging SAM 1066 entry fee this time , as we do not want to built up funds just sitting in the bank doing nothing . With a bit of luck we may get up to 150 or more freeflighters in attendance on the fine day . I suspect that there are not many places in the world where that number gather . lots of walking and hiking sticks on view from folks determined to have a go.
John 

[hastf1b]

Different tailplane!

Hi Tapio, I have not written it is "Number 18". It is the "Ascender" like the left drawing in post # 8.

Heinz

[Red Buzzard]

John T. in #18 above,

Okay, I'll bite. Two questions: Are plans available and why "Zimbabwe". I've looked at the drawing numerous times and never quite figured out why the name.

You are correct. Nice proportions, flat bottomed stab, and could build fairly light for duty in both Nos A and Vintage FAI with a bit of ballast. Interesting.

Bill

[Starduster]

Tapio:

Quick question:

In the scanned image of the drawing from your book (post #22), can you take a look and tell me the dimension that is from the trailing edge of the wing to the leading edge of the stab? The dimension in the image is right on the fold, and I can't make it out.

Thanks

Rich

[Brian J Y]

Hi Rich,

If it's of any use the Zaic yearbook gives 600mm for the Ascender & 629mm for Number 18.

Brian

[mick66]

Hi

the plan I have ... which is the one in the book ...  says 628mm for the #18.

Cheers

Mike

[glidermaster]

What's a single millimetre between friends?
Sorry, 40 thou!

[Tapio Linkosalo]

Five years ago we had a meeting at the Finnish Aviation Museum (next to the Helsinki Airport), where some previous World Champions were presenting their models. Mr Sandy Pimenoff among them. Pentti Reinas took the attached photo of Sandy presenting his model. I think the model currently is at the museum.

 

[Tapio Linkosalo]

Inspired by this thread, I also launched my CorelDraw and imported one of the digitized drawings to it. Here in Finland we do not fly vintage power (nor much of any power), but I felt like the #18 might be an interesting subject for E-36, thus I reduced the size down to 36 in span. Next I would need to send the patterns for laser cutting... I have not figured out the nose length yet, but plan to cut the nose to final length with semi-assembled model, motor and battery in place. I suppose Mick's notes for angles and CG location would be a good starting point.

[FF Bruce]

Tapio,very nice should work well.I've done the same thing but with the Eros FAI model from the late 60's

[Tapio Linkosalo]

I met Sandy yesterday in a model fair here in Helsinki, and asked about the different versions. He told me that the two models were otherwise similar, but "Ascender" had the rectangular tailplane, while #18 sported the elliptical one. He said he used them both at the World Champs, started with Ascender, but at some round was timed an over-run (with big difference in the times of the two timekeepers), and had to fly #18 for that round and then sticked to the latter for the rest of the contest. #18 was called that as it (or he) made 18 maxes in the competition (counting in that one over-run).