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Old Oct 02, 2012, 10:22 AM
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UK south
Joined Dec 2007
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Originally Posted by Paul1PA View Post
Hey Steve,

Yes, the OD of the Radian spar is 10mm. Also, the 75cm length of the HyperFlight carbon spar will be fine (in fact, you'll have to trim off 50mm to match the stock length ).

What is your reason for wanting to use CF? If you're only looking for increased stiffness, one good option is to simply use a Radian Pro wing spar. Both the length and OD are identical but the spar is substantially stiffer. However, since the Pro spar is still fiberglass and has a thicker wall, it is heavier. For comparison, my Radian and Radian Pro spars weigh 21.5 grams and 41.9 grams, respectively. Don't see a published weight for the HyperFlight spar, but being CF it will most likely be stiffer and a bit lighter than the stock Radian spar.

Personally, I like to use the Pro spar in windy/turbulent conditions or when doing aerobatics. Plane seems to handle the flight stress better plus the added mass may help slightly with penetration into the wind.

Hope this helps,

-Paul
Hello Paul and thanks for that information. Like you I have both the Radian and the RP......both of which are, at the moment, 200 miles away, otherwise I might have cottoned on to that solution! The actual weight of the CF tube (10mm OD and 9mm ID) is 24gm per metre length. I might buy a length and try it out, though I quite agree about using the heavier Pro wing spar for windier weather....something I haven't tried yet.

That was useful information and is food for thought - thanks.

Steve
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Old Oct 02, 2012, 10:41 AM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
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The CF spar is heavier than the Radian spar, at 28 grams, and lighter than the RP spar. It is considerably stiffer than the others two. I like the way it flies and the reduced wing flex probably cuts down on the wear and tear in the saddle area.
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Old Oct 02, 2012, 11:53 AM
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USA, CA, Pismo Beach
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Originally Posted by Jovanx View Post
The CF spar is heavier than the Radian spar, at 28 grams, and lighter than the RP spar. It is considerably stiffer than the others two. I like the way it flies and the reduced wing flex probably cuts down on the wear and tear in the saddle area.
Weight is dependent on wall thickness so if the wall is the same as the stock spar it should be lighter shouldn't it? Where did you get your CF spar?
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Old Oct 02, 2012, 12:00 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
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It has the same wall thickness as the RP spar, which is quite a bit thicker than the Radian spar. I got it from Great Hobbies, and it was made by CST The Composites Store. A thinner-walled tube, such as an arrow shaft would still be an improvement over the stock one, and would be the ultimate choice for someone who is serious about keeping the plane light.
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Old Oct 02, 2012, 12:02 PM
St. Louis
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USA, MO, Ballwin
Joined Mar 2010
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The pilot admitted he charged a 1c battery at 4c by mistake. Since the charger and battery were on the curb he did not torch his car.
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Old Oct 02, 2012, 01:35 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
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Ground effect on windy day

One of my favorite things to do with the Radian is to milk the ground effect for all it's worth. If the field is big enough, you can get it down to about 2 feet off the deck and still go an amazing distance before finally setting it onto the grass. My question is...does this still apply when the wind is blowing hard and the plane is hovering in one spot?

On Saturday the Radian was put to the big wind test and it did great. Usually I fly the RP on those days, but it was at home. The wind sock was sticking straight out and there was only one guy flying (an edf jet). I did a few loops and spiral dives just for fun, but most of the time was spent with it pointed into the wind and staying in one place. I did about 5 or 6 vertical landings, and all were good except one was hard enough to knock the canopy off.

One of the landings was amazing, and the pilots who were watching were impressed. It just hung there, hovering 2 feet off the ground, for an unbelievably long time. (gliding, not under power). Was the ground-effect cushion still a factor in this wind?
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Old Oct 02, 2012, 01:40 PM
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"Was the ground-effect cushion still a factor in this wind? "

I think is was but the higher percentage would seem to be with the head wind.
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Old Oct 02, 2012, 06:23 PM
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Originally Posted by Foambird View Post
The pilot admitted he charged a 1c battery at 4c by mistake. Since the charger and battery were on the curb he did not torch his car.
Thanks for the clarifucation. For those not making the connection Foambird is referring to an earlier post about the practice of charging Lipos in a vehicle.
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Old Oct 02, 2012, 08:18 PM
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Originally Posted by Jovanx View Post
One of my favorite things to do with the Radian is to milk the ground effect for all it's worth. If the field is big enough, you can get it down to about 2 feet off the deck and still go an amazing distance before finally setting it onto the grass. My question is...does this still apply when the wind is blowing hard and the plane is hovering in one spot?
When the wind is blowing absolutely steady, it has no effect on rate of descent. However, keep in mind that when you are in ground effect you are very close to the ground which means that any wind will be affected by frictional ground forces and deflect off any discontinuity in the surface. This in turn causes turbulence, which negatively impacts the aircraft's performance, but it may also cause little updrafts which will tend to keep the plane aloft a bit. What I've found though is that these little updrafts generally hit one wing or the other which causes the plane to bob around which is not good if you are trying to get every last little bit of performance out of the plane.

I find that I get the best glide in this situation on absolutely still days. Then the plane seems to want to fly forever, even 12 inches off the ground. It's fun to do, unless you misjudge things a bit and find yourself heading for a fence, curb or pick-nick table, in which case you have to dump the nose real quick and pick up a little grass.

Cliff
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Old Oct 02, 2012, 09:56 PM
Tossing planes into the snow
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Originally Posted by cliffkot View Post
I find that I get the best glide in this situation on absolutely still days. Then the plane seems to want to fly forever, even 12 inches off the ground. It's fun to do, unless you misjudge things a bit and find yourself heading for a fence, curb or pick-nick table, in which case you have to dump the nose real quick and pick up a little grass. Cliff
That's a roger. cliffkot. I like to make circles close to the ground, until the wing tip almost touches, and then the circles have to be bigger. Eventually, the ground effect is exhausted, and the plane is forced to make a perfect soft landing. This is much more difficult with the Radian Pro, because it is moving faster, sideslips more, and is more likely to drag a wing tip on the ground. The ground-effect-effect with the standard Radian is absolutely awesome.
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Old Oct 03, 2012, 06:11 AM
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UK south
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Originally Posted by Jovanx View Post
The CF spar is heavier than the Radian spar, at 28 grams, and lighter than the RP spar. It is considerably stiffer than the others two. I like the way it flies and the reduced wing flex probably cuts down on the wear and tear in the saddle area.
Thanks you for your input, Jovanx.

Steve
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Old Oct 03, 2012, 11:50 AM
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Windsor, Canada, near Detroit
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Originally Posted by Jovanx View Post
One of my favorite things to do with the Radian is to milk the ground effect for all it's worth. If the field is big enough, you can get it down to about 2 feet off the deck and still go an amazing distance before finally setting it onto the grass. My question is...does this still apply when the wind is blowing hard and the plane is hovering in one spot?

On Saturday the Radian was put to the big wind test and it did great. Usually I fly the RP on those days, but it was at home. The wind sock was sticking straight out and there was only one guy flying (an edf jet). I did a few loops and spiral dives just for fun, but most of the time was spent with it pointed into the wind and staying in one place. I did about 5 or 6 vertical landings, and all were good except one was hard enough to knock the canopy off.

One of the landings was amazing, and the pilots who were watching were impressed. It just hung there, hovering 2 feet off the ground, for an unbelievably long time. (gliding, not under power). Was the ground-effect cushion still a factor in this wind?
my view is that, as the wind blows horizontally, it has to be some sort of vertical draft, a surface thermal coming from warm air from the ground, mild but strong enough to keep the plane afloat. i have seen this with some of my planes. i used to fly free flight towline gliders. once early in the morning i launched to test trim with a short line, about 20 feet, and the plane remained turning around at 10 feet for 3 minutes, until the dethermalizer made it drop. it was a surface thermal, not stronger than the plane needed to stay at same level. when the speed of the plane is the same as the wind, and there is a thermal strong enough to balance the weight of the plane, it stays there as hanging from the sky. it also happened to me when flying another r/c sailplane: it didn't move for over 10 minutes. people came asking how was it hanging. i had to bring it down because there was another fellow on same frequency and was asking me how long i would be there.
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Old Oct 03, 2012, 12:09 PM
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Originally Posted by Jovanx View Post
One of the landings was amazing, and the pilots who were watching were impressed. It just hung there, hovering 2 feet off the ground, for an unbelievably long time. (gliding, not under power). Was the ground-effect cushion still a factor in this wind?
Sounds like you would like slope soaring your Radian. I have "parked" the Radian in the air and set the contoller down and watched it just sit there hanging six feet above the ground. Really fun.
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Old Oct 03, 2012, 12:21 PM
Tossing planes into the snow
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Originally Posted by jmps View Post
Sounds like you would like slope soaring your Radian. I have "parked" the Radian in the air and set the contoller down and watched it just sit there hanging six feet above the ground. Really fun.
I have slope soared a couple of times with the Radian Pro and it is a lot of fun. I tried again yesterday but there was barely a breeze and no lift to speak of. It would have been more fun with the Radian. I want to try it with the Radian for sure. The landings up on the mountain are not foam-friendly, and I did some damage to the RP on a sharp rock. Gotta keep practicing those hand-catches.

The scenario I was describing earlier occurred on flat ground, and although it might have looked to the other people that it was just hanging by itself, I was actually very busy operating the elevator stick to make it happen.
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Old Oct 04, 2012, 01:51 AM
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Australia, WA, Perth
Joined Aug 2011
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Less wind I take the Radian out. More wind I take the Radian Pro out.
They are both terrific, just different.
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