SEN 684 - 15 Mar 2002
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SCAT Electronic News 15 March 2002 issue 684
Table of Contents
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FAI Sporting Code - Kaynes
Canards - Segrave
Henry Struck - Stott
Dick Lyons - Thorkildsen
SCAT annual - Brun
Correcting stalls - Schroedter
New Rules - Crowley
Re: flaky airfoils - Gregorie
Free Flight Quarterly, Number 3 - Pudney
Twin props - Segrave
FAI Sporting Code
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Roger
A couple of brief comments on current FAI related discussion points:
1) F1E
The definition of free flight states that and in the F1E rules 3.5.1
My interpretation is that steering may be closed loop - in fact that is
essential, whether magnet or GPS or anything else, since it is required to
sense the models direction of flight and adjust the steering controls to
change that course to the desired one. But the steering cannot be radio or
other control by the competitor during the flight. These are the rules as
they stand now and until the end of 2005. They can be modified in 2005 for
application in 2006.
2) The modified maximum rules. A key point to note is that the 4 min F1A
and 5 min F1B and F1C first round maxes are the standard choice. HOWEVER
different maxima can be set by the organisers if announced in advance (and
which is to be done at Holiday on Ice). Furthermore, these are the intended
max and if there is due reason of weather or recovery conditions it may be
changed on the day. The reason for the new counting system of tkaing the
basic 3 minutes then the extra time to determine ties was to reduce the
reduce the chance that a long difficult max in the first round would be the
sole deciding flight in the competition.
I have been asked to supply the full text of the new rules for SEN. While I
do not mind quoting individual sentences, as in F1E item above, the FAI
policy is that everyone should use a standard rules document. The sporting
code is available from the FAI web site as a PDF document and is thus
frozen and appears the same wherever it is printed. The danger of
publishing it in auxiliary media is that it may get quoted and possible
distorted when not under control, leading to greater confusion. To have the
full rules relevnat to free flight duration flying get volumes F1 and ABR
from
www.fai.org/aeromodelling/documents/sc4.asp
Ian Kaynes
Canards
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Does anyone have or know where I can obtain a plan and 3-view of Burt
Rutan's Long-eze and Vari-eze together with their airfoils, please? Since
both fly with VERY little decalage, perhaps there is something to be learned
here. Not too small, say at least 6" span or larger with foils large in
comparison with the plan. Mike S
Henry Struck
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Got a call from Dick Everet this morning. He tells me the Flying Aces
Trail Blazer of the Air, Hank Struck, had passed away on Sunday night,
Mar 10. A memorial service will be held at Grassy Hill Congregational
Church, in Lyme, CT on Sat. the 16th.
I am sure Henry had more friends than he realized. Anyone who built
one of his many designs would consider himself one. I had felt that way
long before I had the pleasure of meeting him many years ago. And, all
who flew with him have many and varied memories of him to cherish. To
say he will be missed is true. To say he is gone is not true. He has left
us a magnificent legacy.
Dave Stott
Dick Lyons
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You are right John. Dick Lyons was a great guy and we
got to meet him when he move out here during the late
70's or so. He joined the San Valeers for awhile but
eventually migrated to the old timer scif club since I
think that reminded him of his youth the most.
His health really deterioriated over the last year or
so, so that he couldnt compete any more. He was a
true craftsman and all of his models were top notch.
He used to speak proudly of the Chicago aernauts which
he was previously a member of I believe.
He will be missed by us on the West coast. He was a
true gentleman that you could be proud to have as a
friend.
Thermals,
Terry Thorkildsen
SCAT annual
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Correction to the report of the S C A T annual.
The new F A I ruling was employed at the 14 rounder!
Also there were 4 MAXED out in F 1 H , I maxed out the 3 minutes but
did only 211 on the 4 minutes round for the fourth place.
Your's truely
pierre
Correcting stalls
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Roger:
I must first state that I have no formal education in the field of
aerodynamics. What I have learned over the past 60 years has been from
observations and simple trial and error. I haven't the slightest idea
why the designs I made and produced running Champion Model Products for
18 years were so successful in competitions. Dumb luck I would guess.
After the successful introduction of the Champion Coupe and the Up Shot
36" mulvihill, I started on the Wake-up. This was to be a very simple
entry model to build and fly. Very low tech. Back in 1981 I barely
managed to qualify for the team finals to be held at Taft the following
year. My thoughts were: If I placed in the top 10 at the finals, I would
sell a lot of Wake-up kits.
Since the flat bottom section on the Wake-up could not be counted on the
make the required 4-minute first round, I modified the wing and stab. I
used a slightly thinner section that had only 3/32 of undercamber and I
increased the A/R and area of the wing slightly. The stab area was
reduced from 56 in=B2 to 49 in=B2. In July, 1982 I entered the Max Men's
Pierre Classic. In the early morning round the new model flew 5 minutes.
Walt Ghio made about 4=BD minutes and every one else did less than 4
minutes. So I was quite pleased my new Early Bird. But there was one big
problem with this model. When I flew it in lift it would start stalling.
Increasing the glide speed made no difference.
At the team finals in '82 this model did about 5 minutes each of the 3
morning flights. On the second day the air was calm during the second
round, so I used the Early Bird again for an easy max. In the 3rd round
I thought the air was still dead, but it was not. About a minute into
the round the model started stalling and landed 16 seconds short. That
was my second drop, so I figured the top 3 spots were out of reach for
me. But I maxed out the rest of my flights and wound up in 3rd place.
My next task was to solve the stalling problem and then build two more
of these models. Somehow I thought the stab was the problem. Maybe I was
lazy, because I could build a new stab quickly. But by increasing the
camber of the stab and adding a turbulator, the stalling in lift was
eliminated. I'll leave it to the experts to explain why this worked.
How did I due at the WC? I had by far the worst score I ever made in
F1B. The high winds, rain and stupid mistakes left me very embarrassed.
George Schroedter
New Rules
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Will someone, i.e.. Ian Kaynes or anyone else, who has the official wording
for the new flight time scoring rules for FIA,B,C please publish them in the
SEN. This must include under what conditions must these rules be used.
Please don't suggest downloading from the FAI site. I want everyone to see
the same words. I know George had a copy at the Max Men.
Maybe I'm missing something but it seems to me that you produce unsportsmen
like results by taking away time that I have achieved on the clock in the
first round. All time recorded should count! You can't take away time that
has been flown and timed! If I do 299 sec in the first round it must be
included in my final score regardless!
I understand the CIAM's desire to reduce the number in fly-offs. But it
would appear the rule as written is ill conceived at best and totally
unsportsmen like at worst. It can easily be fixed and still reduce the
number in fly-offs. Please Ian, at your upcoming meeting discuss this
inequity and take the steps necessary to rectify the situation.
Thanks, Paul Crowley
Re: flaky airfoils
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Bill Gieskieng wrote:
> The memory comes to me that the late Mike DesJardines tried an Eppler
> E-58 on a Nordic. This section has a very moderate, shallow look in
> the front but accompanied by sizable cusp on the trailing edge. He
> said it drove him nuts, couldn't get it to behave. I believe he ended
> up turbulating the thing ...which of course circumvented its original
> design target. I was a bit concerned in my case since some of my
> "Flapper"sections looked somewhat similar.
>
Years ago I tried the related Eppler E59 on an F1A model. It was a
bear to build, being thin. On top of that I had to laminate the TE,
which was sharply hooked, 30 mm wide, and was only 3mm thick at the
front. I had read Prof. Eppler's warning about stability and so I
used a (considerably) larger tail volume than was then common
practise.
I don't recall any particularly bad stability problems, but
eventually discarded the section because its usable trim range was
far too narrow for reliable performance from the then-current wooden
structures.
HTH
Martin Gregorie
Free Flight Quarterly, Number 3
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Details of the upcoming issue of Free Flight Quarterly are available at
http://users.chariot.net.au/~bluejay/ffqcurrent.html
Jan Pudney
Adelaide, South Australia
Twin props
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I am not the first to try this layout. Emmanuel FILLON had a twin fuselage
Wake a long time ago - I think it was at the time of unlimited rubber, for
he sent me some photcopies of the ship. The twin fuselages were joined by
the flat centresection and the stab at the rear. Both fuselages were diamond
with ,Irecall, freewheel props. He also sent a photocopy of a Coupe with as
he said ONLY 5g of rubber each side which did not augur well for performance
which was a twin also but I can't remember the llayout, partly because the
photcopy was of poor quality and also because he couldn't find a plan of the
ship after so many years!
.....................
Roger Morrell
