Those Whacky RC DS guys

Holy Cow! I hadn't checked YouTube for a while. I'm amazed at the
speeds they're getting.
http://www.youtube.com/watch?v=WaQB16ZaNI4

On 17 Apr, 01:32, Uncle Fuzzy wrote:
Holy Cow! *I hadn't checked YouTube for a while. *I'm amazed at the
speeds they're getting.http://www.youtube.com/watch?v=WaQB16ZaNI4

Thanks - astonishing. 391mph model glider that only weight
a few pounds.

I had a couple of thoughts.

1. I don't believe it - since got over that one, I do believe it now.

2. I wonder how many g they are pulling.

Does 35g seem reasonable?

From video:-

24 secs for 8 laps at say 370mph - max was 375 on that run.

close to 3 secs per lap

370mph = 165m/s

http://www.ajdesigner.com/phpcircula...n_equation.php

T is period

a = v^2 / r

r = vT / 2pi
= 165 * 3 / 2pi
= 78m

a = 165 * 165 / 78
= 349 m/s/s or 35g

This seems like quite a lot but is plausible.

I was expecting a big number since I recall
seeing a jet fighter do a reported 5g turn at
400mph ish and it took a LOT longer than
3 secs per orbit

On Apr 19, 4:50*pm, bod43 wrote:
On 17 Apr, 01:32, Uncle Fuzzy wrote:

Holy Cow! *I hadn't checked YouTube for a while. *I'm amazed at the
speeds they're getting.http://www.youtube.com/watch?v=WaQB16ZaNI4

Thanks - astonishing. 391mph model glider that only weight
a few pounds.

I had a couple of thoughts.

1. I don't believe it - since got over that one, I do believe it now.

2. I wonder how many g they are pulling.

Does 35g seem reasonable?

From video:-

24 secs for 8 laps at say 370mph - max was 375 on that run.

close to 3 secs per lap

370mph = 165m/s

http://www.ajdesigner.com/phpcircula..._acceleration_...

T is period

a = v^2 / r

r = vT / 2pi
* = 165 * 3 / 2pi
* = 78m

a = 165 * 165 / 78
* = 349 m/s/s or 35g

This seems like quite a lot but is plausible.

I was expecting a big number since I recall
seeing a jet fighter do a reported 5g turn at
400mph ish and it took a LOT longer than
3 secs per orbit

I know that modern all CF molded F3B planes snap in short order.
There was a group of guys in Oregon that were on the leading edge of
RC DS'ing. They tried the above mentioned F3B model first, then
designed their own, testing it to 50G's. It folded. I would love to
know just how many G's they're pulling now.

On Apr 19, 8:22*pm, Uncle Fuzzy wrote:
On Apr 19, 4:50*pm, bod43 wrote:



On 17 Apr, 01:32, Uncle Fuzzy wrote:

Holy Cow! *I hadn't checked YouTube for a while. *I'm amazed at the
speeds they're getting.http://www.youtube.com/watch?v=WaQB16ZaNI4

Thanks - astonishing. 391mph model glider that only weight
a few pounds.

I had a couple of thoughts.

1. I don't believe it - since got over that one, I do believe it now.

2. I wonder how many g they are pulling.

Does 35g seem reasonable?

From video:-

24 secs for 8 laps at say 370mph - max was 375 on that run.

close to 3 secs per lap

370mph = 165m/s

http://www.ajdesigner.com/phpcircula..._acceleration_...

T is period

a = v^2 / r

r = vT / 2pi
* = 165 * 3 / 2pi
* = 78m

a = 165 * 165 / 78
* = 349 m/s/s or 35g

This seems like quite a lot but is plausible.

I was expecting a big number since I recall
seeing a jet fighter do a reported 5g turn at
400mph ish and it took a LOT longer than
3 secs per orbit

I know that modern all CF molded F3B planes snap in short order.
There was a group of guys in Oregon that were on the leading edge of
RC DS'ing. *They tried the above mentioned F3B model first, then
designed their own, testing it to 50G's. *It folded. *I would love to
know just how many G's they're pulling now.

Thermal F3B planes snap at 100 mph or so. You do that in the dive-in.

Slope F3F models snap at 200 mph, or a couple of laps.

One production plane has gone over 370 mph. It cost $3 to $4 grand for
the airframe only. Anything faster is custom-made in home workshops
often sing Skunk Works-sourced airfoil profiles and CAD designed CNC
cut wing molds. These guys take this very seriously.

The problem is not continuous g as it makes a lap, it is peak g as the
plane passes the shear layers, a rather violent event. 35 g is a low
estimate.

Consider the D-160" model, which will likely break 400 mph next Santa
Ana season. It weighs 50 pounds and the spar is designed to withstand
over 4000 lbf. So it can over 100g when you consider the wing make
over half the weight of the plane.

In any case, strength is relatively easy to resolve and proper DS
ships rarely clap their wings. A far bigger challenge is in
controlling flutter. One recent design is using mass balancing on the
ailerons and multiple giant scale servos on the ailerons.

Joe Wurts calculated the maximum DS speed to be around 450 mph. The
progress to date has been astounding considering that 200 mph was a
record only 5 years ago.

I can attest that this form of flying it is VERY addicting!

/Adam

Adam wrote:


Consider the D-160" model, which will likely break 400 mph next Santa
Ana season. It weighs 50 pounds and the spar is designed to withstand
over 4000 lbf. So it can over 100g when you consider the wing make
over half the weight of the plane.

50 pounds moving at 400 mph could cause multiple fatalities if it plowed
into some bystanders. How do they make these models safe to fly? Do they
have insurance? How big/heavy can a "model" be before it becomes a UAV,
and perhaps regulated by the FAA?

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Apr 20, 12:47*pm, Eric Greenwell wrote:
Adam wrote:

Consider the D-160" model, which will likely break 400 mph next Santa
Ana season. It weighs 50 pounds and the spar is designed to withstand
over 4000 lbf. So it can over 100g when you consider the wing make
over half the weight of the plane.

50 pounds moving at 400 mph could cause multiple fatalities if it plowed
into some bystanders. How do they make these models safe to fly? Do they
have insurance? How big/heavy can a "model" be before it becomes a UAV,
and perhaps regulated by the FAA?

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes"http://tinyurl.com/y739x4
* * * Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Good point, but even a 1 pound plane could kill you at that speed.
Back in the stone age, when I was slope racing RC gliders, I think the
AMA imposed weight limit was 10 pounds.

On Apr 20, 5:08*pm, Uncle Fuzzy wrote:
On Apr 20, 12:47*pm, Eric Greenwell wrote:



Adam wrote:

Consider the D-160" model, which will likely break 400 mph next Santa
Ana season. It weighs 50 pounds and the spar is designed to withstand
over 4000 lbf. So it can over 100g when you consider the wing make
over half the weight of the plane.

50 pounds moving at 400 mph could cause multiple fatalities if it plowed
into some bystanders. How do they make these models safe to fly? Do they
have insurance? How big/heavy can a "model" be before it becomes a UAV,
and perhaps regulated by the FAA?

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes"http://tinyurl.com/y739x4
* * * Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Good point, but even a 1 pound plane could kill you at that speed.
Back in the stone age, when I was slope racing RC gliders, I think the
AMA imposed weight limit was 10 pounds.

The AMA limit is 55 pounds. However the AMA does not regulate, only
insure, lobby, and liaise. So if you want to be covered by the AMA
policy that membership affords, you best follow the AMA safety code
found he

http://www.modelaircraft.org/files/105.pdf

The FAA has this to say with regards to model aviation:
http://www.modelaircraft.org/files/540-C.pdf

Safety is a concern of course. Often the radar operator will stand
behind a very large pile of rocks or car. But many stand exposed to
the trajectory and by default accept the risks associated with that.

It is difficult to believe but more people have been killed
participating in a thermal duration model sailplane contest that by a
model sailplane engaged in dynamic soaring.

/Adam

Adam wrote:

The AMA limit is 55 pounds. However the AMA does not regulate, only
insure, lobby, and liaise. So if you want to be covered by the AMA
policy that membership affords, you best follow the AMA safety code
found he

http://www.modelaircraft.org/files/105.pdf

Wow, they've really raised the weight limit since I was flying models!

Also, the thermal fliers regularly exceed the 400 feet, don't they? Not
likely an issue for the dynamic soarers, I suppose. Personally, I've
never even seen a model while I've been flying, except waaay down there
on a slope soaring hill.

The FAA has this to say with regards to model aviation:
http://www.modelaircraft.org/files/540-C.pdf

This document is 28 years old. Does the FAA know what's going on now?

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Apr 20, 10:21*pm, Eric Greenwell wrote:


This document is 28 years old. Does the FAA know what's going on now?

Bwahahahaha ROTFL! .... sorry, I couldn't help myself. You mean model
'gliders' aren't made of balsa sticks, tissue, and dope any more??
--
Eric Greenwell - Washington State, USA

On Apr 21, 12:21*am, Eric Greenwell wrote:
Adam wrote:
The AMA limit is 55 pounds. However the AMA does not regulate, only
insure, lobby, and liaise. So if you want to be covered by the AMA
policy that membership affords, you best follow the AMA safety code
found he

http://www.modelaircraft.org/files/105.pdf

Wow, they've really raised the weight limit since I was flying models!

Also, the thermal fliers regularly exceed the 400 feet, don't they? Not
likely an issue for the dynamic soarers, I suppose. Personally, I've
never even seen a model while I've been flying, except waaay down there
on a slope soaring hill.



The FAA has this to say with regards to model aviation:
http://www.modelaircraft.org/files/540-C.pdf

This document is 28 years old. Does the FAA know what's going on now?

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes"http://tinyurl.com/y739x4
* * * Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Eric,

The document is current. Read the following regarding current
developments in UAVs and current model practice (same as 1981):

http://edocket.access.gpo.gov/2007/E7-2402.htm

I repeat, AMA is not "law", just a lobbying group and insurer. I have
no idea from where the 55 pound limit comes.

DS, slope and thermal planes can all easily exceed 400' but FAA
recommends against such activities.

What is your concern with today's modeling practices?

/Adam