SEN 970 - 30 Aug 2005
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SCAT Electronic News 30 August 2005 issue 970
Table of Contents
=================
SEN
F1A D/T Rates - Edge of beyond
Altitude Recorder - Boutillier
Sink Rates - Segrave
Anyone seem the ROW resuts from the NATZ ? - Mate
Details of Sokolovs 57 and 59 Second Place A2 - Ball
2005 FAI Invitational Results - Markos
USSFC - Norval
SEN
====
Firstly the number on the last issue 96d was a typo - it should have
been 969. It is not a move to HEX for some other alien plot or diversion.
I will be travelling more over the next few weeks ... or even months so
this may effect adversally SEN production ..
F1A D/T Rates
=============
EoB
Mr SCAT,
My results from an altitude logger are similar to already published at 2.8 to 3.2
m/s for two diffent models over a number of flights. As is the case with F1As the
models were spinning nose down at I guess about 45 degrees. All the flights were
made in calm air with occasional thermal assistance. Sometime they don't spin and
come down flat but I have no logged data for these conditions.
With a number of people now using loggers (I don't leave home without one) is there
other data that the simulators can use to refine their analyses that can now be
provided ? Can there now be definite conclusions for the performance of flapped
v's non flapped F1A/C (I'm aware of Jan article in the
forthcoming NFFS on this subject), different F1C props, May '99 against
SuperSport gummi and very importantly does a pint of Abbott (english beer) affect
F1C climb heights ?
EoB
Altitude recorder
===========================
Boutillier
In the last SEN issue, Tapio, Matt and Roger wrote about
in board altitude recorders.
Where do they come from ?
Thanks, Thermals.
Bernard
[Bernard
It is the LoLo aka ALTi2 from Roman Vojtech
The web site is www.lomcovak.cz
It is a device originally intended for R/C Soaring and Electric events.
It weighs 9 grams and can capture data in .1 second or longer
increments. Data can be analysed on a PC or Palm. Tapio is one of
the people responsable for the development of the Palm based
analysis tool..
For magic timer users it can be powered by the same battery as the timer.
This makes it particularily attractive for right thinking F1B flyers in
as not extra battery is required. This is less of an issue with F1a and F1C.
There is also a much simpler unit from the model rocketey community that onlt
measures max altitude that can be put on a F1G . I've seen
jack Emery using this but for get the name ... Jack ?
or should this be an attitude recorder ?]
]
Sink rates
==========
Segrave
George Xenakis told me once long ago that all ships D/T down at 10 feet per
second. From the various entries to this discussion, it would appear to be
in the right area. I have used this data for the time since receiving it.
Perhaps some modification for loadings might be in order. A bigger
model(than a Wake) would be more efficient but this would be offset by the
heavier wing loading(bigger models come out heavier by the square/cubed root
formula.) Going the other way, what about lighter ships? i.e., lighter
loading and perhaps size. Is there maybe a minimum loading where the normal
D/T system of tipped stab does not work? I mention this as my latest
tailless Cdh is 18 dm2 wiith a loading of 4.4 gms/dm2 and am in the process
of finding a reliable method apart from throwing the wing off on a string
attached to the fuse. Perhaps bunting the model to come down upside down, in
which case the wing is FLYING the ship down. Gerd Wobbeking has used this
latter system on a P-30 with no damage after a dozen flights.
Best regards
Mike S
Heat is off...
==============
Sweeptte Lee
Aram,
Everyone can decide for themselves...we are all big, adult folk.
No heat crisis exists.
Ciao,
Leeper
More on DT descent rates and angles
===================================
Gregorie
> Thanks heaps for the data Tapio.
> I wonder if you could give a rough estimate of the
> angle of descent in these two cases that you mention ?
> My convention is 90 deg is vertical.
> (Seems that the many theoretical estimates are too high as I suspected. )
>
That sounds right to me: A model on d/t will, to a first approximation,
be falling vertically with respect the the air mass so there should be
no error in a calculated descent rate due to horizontal motion.
The only exception to this is some of the heavier power models (F1Cs)
which do have a forward velocity. I don't know why - maybe its due to a
lower d/t angle than we'd use with an F1A?
Martin
[Martin
You observation on D/T ties in with Ian's in the note below. I know I have more
than 45 degress and it looks like I come down a little faster. But when I try to catch
the mode it is still moving forward slowly and not coming straight down.]
DT descent rate
================
Kaynes
DT Descent Rates
I think Peter was over-simplifying to use flat plate aerodynamic data at
90 deg to the flow. In fact the horizontal speed can be close to the
vertical speed, as estimated by Tapio as a couple of m/sec horizontal
for 2.8 m/sec vertical.
I agree with Peter that beyond stall flat plate aerodynamics are
appropriate but well below 90 deg. Above stall the CP of the flat plate
approximation will move towards 50% chord and this gives a simple
approximation for a CG at 50%. If we can assume that the lift and drag
of the wing dominate then lift, drag and weight all act at 50% giving a
stable flight without any lift or moment from the tail. From this you
can deduce that the descent has the tail is flying at its zero lift
angle and so the descent angle will be close to the tail tip-up angle.
Typical flat plate data gives a flight speed for an F1B of about 4 m/sec
for a 45 degree descent (i.e. 2.8 m/sec down and 2.8 m/sec forward).
This relies on some assumptions but the underlying approximations have
worked well for me in a dynamic analysis to work the tail angle to get
an F1E into a stable descent.
Regards
Ian Kaynes
Anyone seem the ROW resuts from the NATZ ?
=========================================
Mate
I have not seen any ROW results from the Nats. Are there any? Please let
me know. I am working on, as mentioned in my Sympo article a flying
boat. There was an unsuccessful Triumph .49 powered flying boat at the
1946 nats. Anyone remember it? I will be using Meteor I wing and stab on
the "Meteor Boat I". I don't know if there is any advantage other than
not having to worry about misaligned floats. But I pretty much solved
that problem with my setup on the Meteor III as outlined in the Sympo
article if anyone is reading it. By the way you California and Texas
Guys that fly ROW all year round, do you have any tank or pond
guidelines to help us out for the Nats and I hope for the San Champs
(NFFS) for next year? Hey what about ROW Oldtimer and Nostalgia? Ed
Mate
Details of Sokolovs 57 and 59 Second Place A2
==============================================
Ball
Desperately Seeking Sokolov.
It looks like the BMFA will adopt Classic Glider for the 2006 Season,
the Rules are expected to allow designs form the end of the BMFA Vintage
era i.e. Jan 51 up to 1960.
I would like to build a copy of Sokolovs model which is widely regarded
as the starting point for the modern F1A, this model as excited me since
I was a youngster but I only have drawings from Frank Ziacs Year books.
Can any one help with more information particularly details of the wing
centre section, fuselage pylon and colour scheme.
I could do a calculated guess on most of these details but I would
rather have some accurate information, please help.
Regards Phil Ball
2005 FAI Invitational Results
=============================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
45th FAI Invitational, August 27-28, 2005 Muncie.
Although the weather forecast for the weekend was not promising, the
conditions ranged from fair to excellent for Free Flight. That the numbers were down
from previous years may be attributed to the high price of gasoline as well
as the expected conditions. On Friday, those who were on the field to
practice were greeted by overcast sky with light and variable winds. Gil Morris
made the mistake of setting up too near the corn fields and had to retrieve his
model from the same after the variable drift took it into the crop. We set up
in the middle of the field where three-minute practice flights required a
200-meter chase.
The expected rains from the front moving in came in the early morning before
Saturday's flying and were light. A couple of test flights before the rounds
started showed a drift of about one-forth mile for two minutes. However, the
drift at the south end of the field was towards the corn crop and was
expected to change to the SW bringing the cemetery trees into the picture. The FAI
line was moved to the north to avoid the tall corn. AMA soybeans were on the
eastern edge of the field. The first two rounds of F1A, B and C had 3-minute
maxes that were either just short of the beans or just going into them. As
the morning overcast started to break up, the wind velocities increased a bit
and the max was shortened to two minutes to avoid the hardships of walking
through those aforementioned soybeans. Even so, many of the flights that had
strong thermals and long DT durations were at the eastern edge of the field and
required a long hike through the bean crop. It was mentioned that the 2-minute
flights were going the same distance as the previous 3-minute flights.
We suspended rounds 6 and 7 from 2 pm until 4 pm as the internet weather
indicated that strong storms and wind were coming. The forecast was also for
lighter winds by 4 pm. However, by 4 pm a thunderstorm was approaching and I was
beginning to question my own decision to suspend rounds. Luckily, the storm
passed to the south and we were able to start the round on time although many
waited a bit before resuming their flights. Gil Morris was the first one up
and when his flight landed safely, the rest followed.
The fly-off was held at 6:45 pm (sunset was at 7:10) from the best location
we could find for a 5-minute flight. Both F1B and F1C had the same 10-minute
window for launching and happily, most of the contestants still remained to
help time flights. Crowley launched early in the window and seemed to have the
max in hand, but his model started stalling about 2 minutes into the flight
and landed at 4:25, still well on the field. Greg Simon launched near the end
of the window and also developed a stall in the glide, but it dampened out to
beat Paul's flight by 11 seconds. Both models landed on the field. In Power,
Bucky launched early, but his engine quit less than 2 seconds later. The
model made a transition into glide and was not damaged, but did only 72 seconds.
Norman Poti was the only one of the 6 fly-off contestants to make the 5-minute
max and win F1C.
F1A was won in the first seven rounds by Junior Kyle Jones. The only flight
he dropped was because of an early DT. The win cements his position as one
of the three F1A team members to represent the USA in the Junior World
Championships next year in Germany.
For the mini-FAI events on Sunday, the weather was perfect. The skies were
sunny and the breezes were light from the south. We had to adjust the flight
line once as the expected SW breezes never developed, but stayed mostly SSE
throughout the day. Kyle Jones repeated his winning ways by maxing-out F1H to
win. No short DTs this time. In F1G, Fred Blom and John Clapp decided to
settle the fly-off with a 5-minute max at 1:45 pm. John launched his first model
to the left and it crashed. He took out his spare and wound the motor with 3
minutes remaining in the launch window only to see it also hit the ground 13
seconds later due to being under elevated. In the meantime, Fred lit the fuse
on his home-made model and found a nice thermal to max the 5 minutes. His
timer lost the model in the air after 7 minutes, but it was retrieved from the
AMA cornfield on the north border of the property, almost 1.5 miles away.
For the F1J fly-off, a three minute max was used for the first flight. Jim
Haught went early and found some lift as his model glided in very wide circles
on the eastern half of the field. A few seconds later, both Tom Kerr and
Norman Poti launched and did not find lift on the western half of the field. Tom
just made the max by a few seconds, but Norman dropped. In the meantime, Jim's
model DTd into the cornfield by the power lines and he couldn't get a good
directional signal from his locater radio because of those lines. He came back
without the model by the time of the 3:30 second fly-off, but elected to not
fly.
Chuck Markos
F1A Total
Jones, Kyle (J) 180 167 120 120 120 120 120 947
Barron, Peter (S) 157 180 120 94 120 120 120 911
Barron, Andrew 180 123 120 120 120 120 120 903
Markos, Chuck 147 112 120 54 63 120 120 736
F1B
Simon, Greg 180 180 120 120 120 120 120 276 1236
Crowley, Paul 180 180 120 120 120 120 120 265 1225
Lacey, Dave 180 180 120 120 120 120 120 144 1104
Jones, Charlie 180 180 120 120 120 114 120 954
Simon, Evan (S) 180 180 87 120 119 120 9 815
Clapp, John 141 71 120 120 120 120 120 812
Matsuno, Chris 69 154 120 120 104 120 120 807
Seymour, John 174 114 120 34 120 120 120 802
McGlashan, Jerry 173 142 24 339
F1C
Poti, Norman 180 180 120 120 120 120 120 300 1260
Morris, Gil 180 180 120 120 120 120 120 250 1210
Servaites, Bucky 180 180 120 120 120 120 120 72 1032
F1G
Blom, Fred 120 120 120 120 120 300 900
Clapp, John 120 120 120 120 120 13 613
Jones, Charlie 120 120 101 120 120 581
Konefes, Ed 120 120 120 120 94 574
Crowley, Paul 92 105 120 120 120 557
Lacey, Dave 115 81 109 120 119 544
Matsuno, Chris 107 82 120 108 114 531
Simon, Evan (S) 81 31 53 46 67 278
F1H
Jones, Kyle 120 120 120 120 120 600
Chuck Markos 85 78 120 283
Campbell, Lee 6 45 50 101
F1J
Kerr, Tom 120 120 120 120 120 180 154 934
Haught, Jim 120 120 120 120 120 180 780
Poti, Norman 120 120 120 120 120 175 775
USFFC
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Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Roger Have you seen a flyer for the USFFC Labor Day weekend ?
Larry
[No]
....................................
Roger Morrell
