SEN 1836

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Category: Archive 2014
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 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