SEN 1836

 Table of Contents - SEN 1836

  1. Hybrid LDA and Pin Turbs
  2. Fab Feb Recap part 2
  3. AZ Champs Results

 


Ken Bauer on Hybrid LDA and pin turbulators

From FB, ties with the Jim Parker piece in the preeceeding SEN


Ken: Ahhh nothing like aerodynamic experiments on a Saturday morning! Proved that pin turbulators work on new model with Canadian hybrid LDA wings. With turbulators taped to right wing glide turn opened up to almost straight. When taped to left wing the glide circle tightened up to about 35 seconds demonstrating that the turbulated wing has less drag.


Hernan Alarcon Herrera Great test.

Lars Buch Jensen Sounds right.. What was the impact on the bunt sequence?

Tony Mathews Pin turbulators should have lower drag than conventional string or tape turbulators during the launch and bunt. Should be similar to normal turbulators in the glide. The Benedek 6356b (which is what the upper surface of this airfoil matches) must be turbulated to behave properly.

Ken Bauer Tony the pins are 1mm dia and 1mm tall spaced about 45mm apart. They seem to have no effect on the high speed launch or bunt, but do effect straight tow and circle tow as well as the glide of course. They were quickly taped on with some messy masking tape which could also be having an effect but the pins should dominate. Model was trimmed in just a few flights and seems to behave very well so thanks to your team up north for the nice design!



Aram Schlosberg Ken, The Hobbinger article on pin turbulators is a classic. Of course the difficulty is how to implement them. I'm a bit puzzled by the very large distance (45 mm??) between the 1 mm height/diameter pin turbulations. I would expect a much shorter distance, say 4-5 mm, to make them work as advertized.


Javier Abad Ken , from the light picture it seems you used pieces of masking tape and the nylon pieces on top of it....did they hold well after some flights?

Tapio Linkosalo ... and what is the impact of the masking tape on the airflow? Maybe it is a masking-tape-tab-turbulator?


Ken Bauer: The picture doesn't show the pins very well at all. The pins are glued to some thin strips of trim pin stripe tape which are then crudely held in place with the masking tape. So yes the tape will have some effect as well as the pins, but the pins do stick up much higher than the tape. But in any case it proves that turbulators do not need to be a continuous thread or strip but can work at intervals. Yes Aram the article suggests the pins should be placed much closer together like 5 to 10mm. I did some personal experiments a few years ago where I started with closely placed pins and then removed and spread them apart until they quit working. I was surprised and delighted to discover that they could be over 2" apart and still be effective. So the wide spacing is my own idea.

 

Editorial Comment - ken's patience is to be commended - chopping little pieces of nylon line and gluing them on vertically as turbulators. Ken says it is not as bad as it sounds and once you get started it moves right along   Also those of you who have seen ken's molded wing HLGs will be interested to learn that he used these for doing some of the pin turb testing

 

 

Fab Feb Recap - Continued

 

Ike and Kiwi pre-entry

For the Ike and Kiwi we are offering pre-entry by email this year. All payment of entry fees should be made on the field.  You can enter on the field and there is no financial penalty for on the field entry, although it might take a little longer.

In addition to help you plan what events you want to fly in we have listed the events by  day and separated the FAI events from the AMA and NFFS ones. This will help you plan out your day.  So what you do is put your name , country and license (AMA) number in the place below, then delete all the lines of the events you do not want to enter and send it back as a reply to SEN. The parts you send start with the Start of Ike/Kiwi entry form line and end with the End of entry form line.  Below after the blank entry for there is an example of a filled out entry form for someone entering F1B, Mc Cready HLG, F1G and SAM Compressed Air

 

So far Fred Terzian holds the record for the max number of events entered, closely followed by the Leeper.  To match Fred the Leeper would need to dig that Mean Machine out of the attic.



Start of IKE/Kiwi Entry Form
Name:
Country:
License Number:
Saturday FAI events:
Kiwi-New Zealand World Cup

F1A
F1B
F1C
F1P

Saturday AMA/NFFS
MacCready HLG
E-36 World Open
E-20
Big E
Vintage FAI Gas
AMA CLG, Nat Cup
Gollywock one-design
1/4A Nos Gas
1/2A Nos Gas
C Nos Gas
AMA Gas C, D and Super D combined

Sunday FAI:
F1Q (World Cup)
F1G
F1H
F1J

Sunday AMA/NFFS
MacCready CLG
E-36 Mass Launch
A Nos Gas
B Nos Gas
Early 1/2A Nos Gas
AMA Gas 1/2A, A and B combined
AMA HLG, Nat Cup
P-30
Large Nos Rubber & Nos Wake
Moffett
Classic Glider
SAM Compressed Air
BTV West 12” CLG

Monday
F1E Kiwi World Cup
End of Entry form





**************************start of example
Start of IKE/Kiwi Entry Form Name: Edward Gibbon Wakefield
Country: New Zealand
License Number: NZL AM1840
Saturday FAI events:
Kiwi-New Zealand World Cup
F1B
Saturday AMA/NFFS
MacCready HLG
Sunday FAI:
F1G
Sunday AMA/NFFS
SAM Compressed Air
End of Entry form
*********************************end of example

 

 

 

AZ Champs Results


Round                   1      2      3      4      5      6      7  FO1  TOTAL
F1A
Name
Brian Van Nest 180 180 180 180 180 180 180 348 1608
Shlomi Rosenzweig 180 180 180 180 180 180 180 167 1427
Enis Pecenkovic 180 180 180 180 180 180 180 18 1278
Jim Farmer 180 180 180 180 180 180 156 1236
Jim Parker 180 180 180 180 180 180 135 1215
Lee Hines 180 180 133 146 180 180 180 1179
Peter Brocks 180 180 180 180 60 152 180 1112
Andrew Barron 20 180 180 180 180 180 180 1100
Peter Alnutt 150 50 180 180 180 180 180 1100
Jasminka PecenkoviC 180 180 180 180 105 180 71 1076
Don Zink 180 139 DNF 319
Dick Nelson 97 DNF 97

F1B
Tom Ioerger 166 180 180 180 172 DNF 878
Dick Wood 177 171 180 136 180 DNF 844

F1C
Matt Gewain DNF DND 123 DNF 123

F1G FO1
Tom Ioreger 120 120 120 120 120 178 778
Peter Brocks 120 120 120 120 120 154 754

F1H
Jim Parker 120 120 120 120 120 135 735
Lee Hines 120 120 120 120 120 104 704
Brian Van Nest 120 120 108 120 120 588

Elmer Nelson, CD



.....

 

Roger Morrell