Arduino Based Soaring Related Devices

Its all vary admirable that you are trying to calulate the nominal load while under tow, but it is not needed for the task at hand. You just need to know when it is non zero. A simple push button switch such that when the cable is under load it pushes on the switch. Design a link that come in contact under load. All the load goes to the link, and the switch detects that it is closed. A light spring seperates the link to open the contact with an empty rope. The monitor sees that the link is open and if open long enough (longest conceivable slack rope duration) and records the hight when it first went slack.

All that said, Eric's human factors solution (don't do soft releases, or say "thanks" on the radio) will avoid over charge.

On Sunday, December 20, 2020 at 6:46:35 AM UTC-6, Lauren Rezac wrote:
On Saturday, December 19, 2020 at 8:42:08 AM UTC-6, wrote:
Hi Lauren,

To keep the traffic down on this thread lets start an off line conversation to get you all the info and file and answer questions. Unfortunately I'm not able to reply directly to you. Do you have the same limitation? If so then please include your email on your next post.

Bill
On Saturday, December 19, 2020 at 8:06:21 AM UTC-5, Lauren Rezac wrote:
On Friday, December 18, 2020 at 10:16:46 AM UTC-6, wrote:
Over the last two years I've designed and built three Arduino based soaring related devices.. They a 1) Tow Altitude Recorder with tow plane and ground units, 2) Cockpit Dual Battery Voltage & Temp Monitor, and 3)Trailer Lights Monitor.
Yes I am interested in the battery temp/voltage unit. (info on the other two might also be helpful

Thanks,

Lauren
Bill,

It is



Thanks,

Lauren Rezac
Bill,

Well that's interesting. It seem to remove all reference to email addresses. So lets try this a different way.

rezac6205

is the first part of the email then the at and comcast.net

Thanks,

Lauren

On Sat, 19 Dec 2020 20:22:36 -0800, Eric Greenwell wrote:

Doesn't the majority of the wash or downflow from the wing pass under
the glider if it tows at the same altitude as the tug?

Thats definitely the case for a narrow layer containing propwash and
turbulence coming off the tug wing: quite obvious when you hit it, but
there's a general downflow above and below that turbulent sheet and a
matching upflow beyond the tug wingtips which can be seen in both flow
visualizations and, in some cases, in photos of aircraft flying in foggy
conditions which show the upflow extending out beyond the wingtips to at
least half of each wing semi-span. After all, wing lift is essentially
due to momentum transfer: a mass of air with a momentum equivalent to the
aircraft weight is being deflected downward by the wings, so this air
mass must occupy a fairly large volume below and behind the aircraft.

I still have vivid memories of going to Chobham Common for a spot of
model flying on a calm day with a solid, cloud base at 1000-1500 ft. The
road we were on was directly along the Heathrow approach path and we were
heading west, away from Heathrow. Suddenly a 747 dropped out of the
overcast ahead of us with flaps and wheels down. Its wing was scooping
off the bottom of the cloud layer and hurling it downwards, making the
downflow clearly visible under its wing. It must have extended down
20-25% of the wingspan, so was very clearly visible: looking at it was
like seeing the Niagara Falls streaming down below the wing, making it
quite obvious that this downflow was supporting 180 tons of aircraft.

For example, I
used to demonstrate the ease of positioning behind the towplane to
students by banking to left until the glider was way off center line,
and I never noticed any significant difference in the airflow from
center to far out to the left. This was with a 200' long towrope;
perhaps, with a much shorter rope, the experience would be a lot
different.

Yes, but that's in a fairly lightly loaded training glider. Some high
span competition types, e.g a JS-1C when fully ballasted, need a high tow
speed to avoid tip stalling. I've seen an absolute minimum tow speed of
77 kts quoted for a fully ballasted JS-1C. It seems likely that this is
at least partly due to the change in incident airflow along the wingspan
from the downflowing field behind the tug to the upflowing field which
extends much further out than its wingtips and immediate tip vortex. The
effect is to put the glider's tips at a higher AOA than the root, thus
cancelling the effect of any built-in washout in the wing.


--
--
Martin | martin at
Gregorie | gregorie dot org

Lauren Rezac wrote on 12/20/2020 4:51 AM:
On Sunday, December 20, 2020 at 6:46:35 AM UTC-6, Lauren Rezac wrote:
On Saturday, December 19, 2020 at 8:42:08 AM UTC-6, wrote:
Hi Lauren,

To keep the traffic down on this thread lets start an off line conversation to get you all the info and file and answer questions. Unfortunately I'm not able to reply directly to you. Do you have the same limitation? If so then please include your email on your next post.

Bill
On Saturday, December 19, 2020 at 8:06:21 AM UTC-5, Lauren Rezac wrote:
On Friday, December 18, 2020 at 10:16:46 AM UTC-6, wrote:
Over the last two years I've designed and built three Arduino based soaring related devices.. They a 1) Tow Altitude Recorder with tow plane and ground units, 2) Cockpit Dual Battery Voltage & Temp Monitor, and 3)Trailer Lights Monitor.
Yes I am interested in the battery temp/voltage unit. (info on the other two might also be helpful

Thanks,

Lauren
Bill,

It is



Thanks,

Lauren Rezac
Bill,

Well that's interesting. It seem to remove all reference to email addresses. So lets try this a different way.

rezac6205

is the first part of the email then the at and comcast.net

Thanks,

Lauren

I get RAS via emails, and they always include the poster's email address in the header, and
your email address is in the body in your reply. Now I'm curious: do you see your full email
address he

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On 12/20/2020 9:04 AM, Eric Greenwell wrote:
Lauren Rezac wrote on 12/20/2020 4:51 AM:
On Sunday, December 20, 2020 at 6:46:35 AM UTC-6, Lauren Rezac wrote:
On Saturday, December 19, 2020 at 8:42:08 AM UTC-6,
wrote:
Hi Lauren,

To keep the traffic down on this thread lets start an off line
conversation to get you all the info and file and answer questions.
Unfortunately I'm not able to reply directly to you. Do you have the
same limitation? If so then please include your email on your next
post.

Bill
On Saturday, December 19, 2020 at 8:06:21 AM UTC-5, Lauren Rezac wrote:
On Friday, December 18, 2020 at 10:16:46 AM UTC-6,
wrote:
Over the last two years I've designed and built three Arduino
based soaring related devices.. They a 1) Tow Altitude Recorder
with tow plane and ground units, 2) Cockpit Dual Battery Voltage &
Temp Monitor, and 3)Trailer Lights Monitor.
Yes I am interested in the battery temp/voltage unit. (info on the
other two might also be helpful

Thanks,

Lauren
Bill,

It is



Thanks,

Lauren Rezac
Bill,

Â* Well that's interesting. It seem to remove all reference to email
addresses. So lets try this a different way.

rezac6205

is the first part of the email then the at and comcast.net

Thanks,

Lauren

I get RAS via emails, and they always include the poster's email address
in the header, and your email address is in the body in your reply. Now
I'm curious: do you see your full email address he


If you read RAS through the Google Groups web site it usually masks part
of any email address. I used to access RAS that way, but after they
switched to their new dumbed down format (lacking reply-to-author-only)
I switched to using Mozilla Thunderbird reading the posts via
eternal-september. Another option for reading (not posting?) via a web
browser is he
https://rec.aviation.soaring.narkive.com/

On Sunday, 20 December 2020 at 14:01:25 UTC, Martin Gregorie wrote:
On Sat, 19 Dec 2020 20:22:36 -0800, Eric Greenwell wrote:

Doesn't the majority of the wash or downflow from the wing pass under
the glider if it tows at the same altitude as the tug?

Thats definitely the case for a narrow layer containing propwash and
turbulence coming off the tug wing: quite obvious when you hit it, but
there's a general downflow above and below that turbulent sheet and a
matching upflow beyond the tug wingtips which can be seen in both flow
visualizations and, in some cases, in photos of aircraft flying in foggy
conditions which show the upflow extending out beyond the wingtips to at
least half of each wing semi-span. After all, wing lift is essentially
due to momentum transfer: a mass of air with a momentum equivalent to the
aircraft weight is being deflected downward by the wings, so this air
mass must occupy a fairly large volume below and behind the aircraft.

I still have vivid memories of going to Chobham Common for a spot of
model flying on a calm day with a solid, cloud base at 1000-1500 ft. The
road we were on was directly along the Heathrow approach path and we were
heading west, away from Heathrow. Suddenly a 747 dropped out of the
overcast ahead of us with flaps and wheels down. Its wing was scooping
off the bottom of the cloud layer and hurling it downwards, making the
downflow clearly visible under its wing. It must have extended down
20-25% of the wingspan, so was very clearly visible: looking at it was
like seeing the Niagara Falls streaming down below the wing, making it
quite obvious that this downflow was supporting 180 tons of aircraft.
For example, I
used to demonstrate the ease of positioning behind the towplane to
students by banking to left until the glider was way off center line,
and I never noticed any significant difference in the airflow from
center to far out to the left. This was with a 200' long towrope;
perhaps, with a much shorter rope, the experience would be a lot
different.

Yes, but that's in a fairly lightly loaded training glider. Some high
span competition types, e.g a JS-1C when fully ballasted, need a high tow
speed to avoid tip stalling. I've seen an absolute minimum tow speed of
77 kts quoted for a fully ballasted JS-1C. It seems likely that this is
at least partly due to the change in incident airflow along the wingspan
from the downflowing field behind the tug to the upflowing field which
extends much further out than its wingtips and immediate tip vortex. The
effect is to put the glider's tips at a higher AOA than the root, thus
cancelling the effect of any built-in washout in the wing.
--
--
Martin | martin at
Gregorie | gregorie dot org

I agree with Martin's explanation. To my mind the fullest account of the issues towing very high wing-loading long span gliders is by Aldo Cernezzi in the Jan-Feb issue of Gliding International. The article is slightly misleadingly titled "The Creation of a Vortex". As the ex-owner of a JS1c 21m who had just launched in it before a fatal towing accident in another 21m JS1c my mind became very concentrated on this issue. I subsequently never launched it fully ballasted in 21m mode without getting a direct confirmation from the tow pilot that the minimum speed would be 75 knots. Not least because the ASIs in many tug planes over-read in flight as they don't use proper statics.

On Sunday, 20 December 2020 at 16:52:39 UTC, John Galloway wrote:
On Sunday, 20 December 2020 at 14:01:25 UTC, Martin Gregorie wrote:
On Sat, 19 Dec 2020 20:22:36 -0800, Eric Greenwell wrote:

Doesn't the majority of the wash or downflow from the wing pass under
the glider if it tows at the same altitude as the tug?

Thats definitely the case for a narrow layer containing propwash and
turbulence coming off the tug wing: quite obvious when you hit it, but
there's a general downflow above and below that turbulent sheet and a
matching upflow beyond the tug wingtips which can be seen in both flow
visualizations and, in some cases, in photos of aircraft flying in foggy
conditions which show the upflow extending out beyond the wingtips to at
least half of each wing semi-span. After all, wing lift is essentially
due to momentum transfer: a mass of air with a momentum equivalent to the
aircraft weight is being deflected downward by the wings, so this air
mass must occupy a fairly large volume below and behind the aircraft.

I still have vivid memories of going to Chobham Common for a spot of
model flying on a calm day with a solid, cloud base at 1000-1500 ft. The
road we were on was directly along the Heathrow approach path and we were
heading west, away from Heathrow. Suddenly a 747 dropped out of the
overcast ahead of us with flaps and wheels down. Its wing was scooping
off the bottom of the cloud layer and hurling it downwards, making the
downflow clearly visible under its wing. It must have extended down
20-25% of the wingspan, so was very clearly visible: looking at it was
like seeing the Niagara Falls streaming down below the wing, making it
quite obvious that this downflow was supporting 180 tons of aircraft.
For example, I
used to demonstrate the ease of positioning behind the towplane to
students by banking to left until the glider was way off center line,
and I never noticed any significant difference in the airflow from
center to far out to the left. This was with a 200' long towrope;
perhaps, with a much shorter rope, the experience would be a lot
different.

Yes, but that's in a fairly lightly loaded training glider. Some high
span competition types, e.g a JS-1C when fully ballasted, need a high tow
speed to avoid tip stalling. I've seen an absolute minimum tow speed of
77 kts quoted for a fully ballasted JS-1C. It seems likely that this is
at least partly due to the change in incident airflow along the wingspan
from the downflowing field behind the tug to the upflowing field which
extends much further out than its wingtips and immediate tip vortex. The
effect is to put the glider's tips at a higher AOA than the root, thus
cancelling the effect of any built-in washout in the wing.
--
--
Martin | martin at
Gregorie | gregorie dot org
I agree with Martin's explanation. To my mind the fullest account of the issues towing very high wing-loading long span gliders is by Aldo Cernezzi in the Jan-Feb issue of Gliding International. The article is slightly misleadingly titled "The Creation of a Vortex". As the ex-owner of a JS1c 21m who had just launched in it before a fatal towing accident in another 21m JS1c my mind became very concentrated on this issue. I subsequently never launched it fully ballasted in 21m mode without getting a direct confirmation from the tow pilot that the minimum speed would be 75 knots. Not least because the ASIs in many tug planes over-read in flight as they don't use proper statics.

To correct myself. The main article is called Poor Handling on Tow. The above mentioned article follows on from it.

John Galloway wrote on 12/20/2020 11:01 AM:
On Sunday, 20 December 2020 at 16:52:39 UTC, John Galloway wrote:
On Sunday, 20 December 2020 at 14:01:25 UTC, Martin Gregorie wrote:
On Sat, 19 Dec 2020 20:22:36 -0800, Eric Greenwell wrote:

Doesn't the majority of the wash or downflow from the wing pass under
the glider if it tows at the same altitude as the tug?

Thats definitely the case for a narrow layer containing propwash and
turbulence coming off the tug wing: quite obvious when you hit it, but
there's a general downflow above and below that turbulent sheet and a
matching upflow beyond the tug wingtips which can be seen in both flow
visualizations and, in some cases, in photos of aircraft flying in foggy
conditions which show the upflow extending out beyond the wingtips to at
least half of each wing semi-span. After all, wing lift is essentially
due to momentum transfer: a mass of air with a momentum equivalent to the
aircraft weight is being deflected downward by the wings, so this air
mass must occupy a fairly large volume below and behind the aircraft.

I still have vivid memories of going to Chobham Common for a spot of
model flying on a calm day with a solid, cloud base at 1000-1500 ft. The
road we were on was directly along the Heathrow approach path and we were
heading west, away from Heathrow. Suddenly a 747 dropped out of the
overcast ahead of us with flaps and wheels down. Its wing was scooping
off the bottom of the cloud layer and hurling it downwards, making the
downflow clearly visible under its wing. It must have extended down
20-25% of the wingspan, so was very clearly visible: looking at it was
like seeing the Niagara Falls streaming down below the wing, making it
quite obvious that this downflow was supporting 180 tons of aircraft.
For example, I
used to demonstrate the ease of positioning behind the towplane to
students by banking to left until the glider was way off center line,
and I never noticed any significant difference in the airflow from
center to far out to the left. This was with a 200' long towrope;
perhaps, with a much shorter rope, the experience would be a lot
different.

Yes, but that's in a fairly lightly loaded training glider. Some high
span competition types, e.g a JS-1C when fully ballasted, need a high tow
speed to avoid tip stalling. I've seen an absolute minimum tow speed of
77 kts quoted for a fully ballasted JS-1C. It seems likely that this is
at least partly due to the change in incident airflow along the wingspan
from the downflowing field behind the tug to the upflowing field which
extends much further out than its wingtips and immediate tip vortex. The
effect is to put the glider's tips at a higher AOA than the root, thus
cancelling the effect of any built-in washout in the wing.
--
--
Martin | martin at
Gregorie | gregorie dot org
I agree with Martin's explanation. To my mind the fullest account of the issues towing very high wing-loading long span gliders is by Aldo Cernezzi in the Jan-Feb issue of Gliding International. The article is slightly misleadingly titled "The Creation of a Vortex". As the ex-owner of a JS1c 21m who had just launched in it before a fatal towing accident in another 21m JS1c my mind became very concentrated on this issue. I subsequently never launched it fully ballasted in 21m mode without getting a direct confirmation from the tow pilot that the minimum speed would be 75 knots. Not least because the ASIs in many tug planes over-read in flight as they don't use proper statics.

To correct myself. The main article is called Poor Handling on Tow. The above mentioned article follows on from it.

Did all these accidents/incidents occur while the glider was at the altitude as the tow plane?
What was the length of the tow rope in use?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On 12/20/2020 9:01 AM, Martin Gregorie wrote:
On Sat, 19 Dec 2020 20:22:36 -0800, Eric Greenwell wrote:

Doesn't the majority of the wash or downflow from the wing pass under
the glider if it tows at the same altitude as the tug?

Thats definitely the case for a narrow layer containing propwash and
turbulence coming off the tug wing: quite obvious when you hit it, but
there's a general downflow above and below that turbulent sheet and a
matching upflow beyond the tug wingtips which can be seen in both flow
visualizations and, in some cases, in photos of aircraft flying in foggy
conditions which show the upflow extending out beyond the wingtips to at
least half of each wing semi-span. After all, wing lift is essentially
due to momentum transfer: a mass of air with a momentum equivalent to the
aircraft weight is being deflected downward by the wings, so this air
mass must occupy a fairly large volume below and behind the aircraft.

I still have vivid memories of going to Chobham Common for a spot of
model flying on a calm day with a solid, cloud base at 1000-1500 ft. The
road we were on was directly along the Heathrow approach path and we were
heading west, away from Heathrow. Suddenly a 747 dropped out of the
overcast ahead of us with flaps and wheels down. Its wing was scooping
off the bottom of the cloud layer and hurling it downwards, making the
downflow clearly visible under its wing. It must have extended down
20-25% of the wingspan, so was very clearly visible: looking at it was
like seeing the Niagara Falls streaming down below the wing, making it
quite obvious that this downflow was supporting 180 tons of aircraft.

For example, I
used to demonstrate the ease of positioning behind the towplane to
students by banking to left until the glider was way off center line,
and I never noticed any significant difference in the airflow from
center to far out to the left. This was with a 200' long towrope;
perhaps, with a much shorter rope, the experience would be a lot
different.

Yes, but that's in a fairly lightly loaded training glider. Some high
span competition types, e.g a JS-1C when fully ballasted, need a high tow
speed to avoid tip stalling. I've seen an absolute minimum tow speed of
77 kts quoted for a fully ballasted JS-1C. It seems likely that this is
at least partly due to the change in incident airflow along the wingspan
from the downflowing field behind the tug to the upflowing field which
extends much further out than its wingtips and immediate tip vortex. The
effect is to put the glider's tips at a higher AOA than the root, thus
cancelling the effect of any built-in washout in the wing.

See: https://www.youtube.com/watch?v=WIZWzvMu1dM from time 13:40
Hope that's clear,
Best Regards, Dave

""If anyone is interested in building any of these devices I can provide a parts list, schematics, controller code, STL files for the enclosures, and more operational details. ""


Upload them to GitHub or Hackaday.io