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Old Sep 19, 2012, 12:13 PM
Gopher huntin' stick jockey
turboparker's Avatar
East Bethel, MN USA
Joined Jul 2009
11,539 Posts
Quote:
Originally Posted by KLRico View Post
I don't really think the RP is the best choice for rough air. Under the conditions you're talking about, you can definately tell you're flying something made of foam.

It can be done, but you'd probably appreciate a stiffer/heavier airframe for that kind of flying.
Quote:
Originally Posted by Jovanx View Post
Here is a video of slope soaring with the RP in a fairly stiff wind. It has had a few mods (mostly replacing fiberglass with carbon fiber) to stiffen it up. Most people use a heavier battery for slope soaring, bit this was just with the stock 1300. This plane handles the wind very well for a foamy.

http://www.rcgroups.com/forums/showp...ostcount=10303
Quote:
Originally Posted by aeajr View Post
Joel,

You don't say in your post but I presume you are talking about slope soaring. Thermal soarng in 20-30 mph would be at the extreme limit of most high end thermal gliders. Except for a contest situation, wind speeds of that level would keep my thermal gliders in the racks.

You can weight up a Radian Pro with a steel rod inside the wing joiner rod, but I would consider 20 to 30 mph to be at the extreme limit of the RP for good flying on the slope. It is designed as themal soaring ship rather than a slope soarer. So the optimum speed range is to the lower end.

But as a plane that will do well in light slope winds that you can weight up for moderate conditions (10 to 20) I think it would be good.

It is not highly aerobatic. The roll rate is not high so if you want to do a lot of spinning and such, there would be better choices. But you can roll it.

The foam nature of the RP is fairly flexible as compared to a balsa or molded plane. If you have rough landing areas, foam is great.

If you are looking more for real performance, crisp aerobatics and high speeds I would think there are better choices.

Hope that is helpful.
Guys,

Thanks for the great info! At this point, I'm exploring my options. See my post in the other thread for more details of what I'm looking for. Maybe I'm asking for a plane that doesn't exist.

Jovanx,

That was some great flying! Looks like you've got her dialed-in for SS. What all was involved in strengthening the airframe? I often set up RF for similar conditions & have fun surfing the ridge lift with a wide range of sailplanes. Unfortunately, it doesn't get much flatter than it is around here. I think I'd have to drive a few hours to find a suitable spot for SS with a 2 meter ship. But I'd still be interested in strengthening the airframe if I were to go this route.

Joel
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Old Sep 19, 2012, 12:41 PM
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South Africa, WC, Cape Town
Joined Oct 2011
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Hi KLrico,
I fly at an RC club, we have two cross runways that are about 130 yards long and 6 yards wide.
it is situated in a farm and surrounded by fields (currently Canola) and wheat.

In hot days (I flew on Saturday and Sunday) there is a considerable temp differecence between the runways and the rest of the ground and we (other chaps who also fly gliders besides powered planes) search for thermals downwind of the runways.
It is obviously possible that in these days there were none or insufficienct thermals.

JumpySticks,
I know that nothing works without a battery connected.
However, I can turn the prop easily by hand but when I flew the RP I observed that as soon as I cut the throttle the prop folded and stayed in the position where it folded.

I'll try to listen to the motor when I turn it and see if there's any whine.
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Old Sep 19, 2012, 01:11 PM
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Originally Posted by Danny_l View Post
I may have misundertood you whe you directed me to the video, it made me think that unless I do all these mods I cannot expect much from the RP. (this is pretty much the message that Paul passes).
Not quite. What he wrote was:

"Out of the box, the Radian is flyable for sure, but it certainly does not handle as well as it should, nor glide as efficiently as it could."

I think what he meant was that it did not fly to his high standards. I flew a stock model for a year before making his mods and was satisfied with it, but it did fly better afterward.

Quote:
... will set the CG again to somewhere around 80mm and use the lightest battery that I have (1800 Mah).
Rather than going with an arbitrary CG; before your next powered flight do some motor-off glide tests with neutral elevator trim, and adjust the CG to get the best possible glide.
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Old Sep 19, 2012, 01:44 PM
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eroeder's Avatar
United States, TX, Frisco
Joined Jan 2004
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For all you experienced mod'ers, I need advice. As the weight of my bird goes up, what are some things I can do to strengthen the wing saddle to support plane in flight? I can see the screw hole foam is getting worn out and I want to keep the wing from folding. Pics would be nice. At my current weight 54oz with 2200mah flies great and stable, but I am going to convert to 4400mah (two 2200mah)- strapped along fuselage under each wing. I will make foam piece to make aerodynamic and will look like "fusealage blisters." this should give me about 40mins of FPV.

So far, I upgraded to a carbon spar and have carbon stiffners in horizontal stab, vertical stab, carbon stiffner inside all control surfaces, wood piece to lessen tail flex, and control hinges on all surfaces. Prop swap has me at 240-270watts, and HK motor swap should add a few watts at a lighter weight.
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Old Sep 19, 2012, 02:45 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
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Quote:
Originally Posted by turboparker View Post
What all was involved in strengthening the airframe? I often set up RF for similar conditions & have fun surfing the ridge lift with a wide range of sailplanes.
An arrow shaft is used along the underside of the fuselage to either augment or replace the fiberglass "stiffener". Then a couple of CF "skewers" are inserted into the vertical stabilizer. They are both easy mods and well worth the effort. Then the removable fiberglass wing spar is replaced with a CF one. The plane ends up being lighter, stiffer, and more responsive.

I actually enjoy the standard Radian a bit more for general thermal hunting, but when the wind comes up the RP comes out. Having the ailerons and very little dihedral makes it more stable in gusty wind conditions. If you are looking for links to the mods, I can dig them up for you.
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Old Sep 19, 2012, 04:03 PM
Gopher huntin' stick jockey
turboparker's Avatar
East Bethel, MN USA
Joined Jul 2009
11,539 Posts
Quote:
Originally Posted by Jovanx View Post
An arrow shaft is used along the underside of the fuselage to either augment or replace the fiberglass "stiffener". Then a couple of CF "skewers" are inserted into the vertical stabilizer. They are both easy mods and well worth the effort. Then the removable fiberglass wing spar is replaced with a CF one. The plane ends up being lighter, stiffer, and more responsive.

I actually enjoy the standard Radian a bit more for general thermal hunting, but when the wind comes up the RP comes out. Having the ailerons and very little dihedral makes it more stable in gusty wind conditions. If you are looking for links to the mods, I can dig them up for you.
A lighter, stiffer, and more responsive airframe is a good thing in my book. One can always add ballast if extra weight is needed. I would definitely appreciate the links - thanks!

Joel
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Old Sep 19, 2012, 06:46 PM
Drifting off the reservation..
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USA, LA, Broussard
Joined Jan 2011
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The only downside to making it stiffer is that the plane is more likely to break when striking an object. The flex makes the plane very durable.
If you add stiffeners, the shock is transferred to the end of the stiffener, and the plane breaks there.
It's a trade off.
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Old Sep 19, 2012, 07:38 PM
Tossing planes into the snow
Canada, BC, Smithers
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Quote:
Originally Posted by turboparker View Post
A lighter, stiffer, and more responsive airframe is a good thing in my book. One can always add ballast if extra weight is needed. I would definitely appreciate the links - thanks! Joel
People have used various methods to make this plane more responsive. Here are my methods;

Elevator fix - works great on the PZ warbirds as well
http://www.rcgroups.com/forums/showp...postcount=7896

Vertical stab
http://www.rcgroups.com/forums/showp...ostcount=12837

Fuselage
http://www.rcgroups.com/forums/showp...ostcount=12370

Then of course there is replacing the stock fiberglass wing spar with a CF one (not a thin-walled arrow). Instant weight savings and performance increase. The wings stop flapping and the ailerons are more effective.
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Old Sep 19, 2012, 08:50 PM
Gopher huntin' stick jockey
turboparker's Avatar
East Bethel, MN USA
Joined Jul 2009
11,539 Posts
JumpySticks,

Yes - engineering is an exercise in compromise, and every system has a 'fuse', so-to-speak. I do place a high priority on in-flight strength & flight-performance. However, it has been nearly three decades since I last considered 'crashability' important when choosing an RC plane. As the saying goes - high-performance aircraft are designed to fly well - not crash well.

Jovanx,

Thanks for the links! What size CF spar is required for the wing? I'd be interested in doing that during the 'build', if I were to go this route.

Joel
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Old Sep 19, 2012, 09:19 PM
Tossing planes into the snow
Canada, BC, Smithers
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Quote:
Originally Posted by turboparker View Post
As the saying goes - high-performance aircraft are designed to fly well - not crash well.
Agreed. I believe that if the responsiveness can be improved, you are also less likely to crash it. The spar is 3/8" and has been much-discussed on this thread. No one who has tried it wants to go back to the stock FG spar, as it makes a huge difference. A little work can make this into a great plane, and it says a lot that so many people have more than one of them.
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Old Sep 19, 2012, 09:23 PM
Drifting off the reservation..
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USA, LA, Broussard
Joined Jan 2011
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Quote:
Originally Posted by turboparker View Post
JumpySticks,

Yes - engineering is an exercise in compromise, and every system has a 'fuse', so-to-speak. I do place a high priority on in-flight strength & flight-performance. However, it has been nearly three decades since I last considered 'crashability' important when choosing an RC plane. As the saying goes - high-performance aircraft are designed to fly well - not crash well.

Jovanx,

Thanks for the links! What size CF spar is required for the wing? I'd be interested in doing that during the 'build', if I were to go this route.

Joel
Well said. If you are proficient enough that a crash is unlikely, then a stiffer plane is going to be more to your liking. Most of the high end stiff carbon fiber planes have enough strength to withstand just about any aerobatic gyration you can throw at them. Just don't bang the wing into a pole as I am prone to do.

The Radian Pro is probably designed for less experienced fliers who are likely to botch a landing or two.

I agree with 100% Jovanx on the wing spar. I use a very lightweight CF arrowshaft .380mm outside diameter with a thicker CF crossbow shaft slipped inside which is about 3" shorter than the outer shaft. Sort of a laminated effect which only weighs about 1.5 oz total. Much lighter than the stock shaft but about as stiff as you can get. I haven't stiffened the fuselage though because I really want to keep the weight down for thermal flying.
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Old Sep 19, 2012, 09:39 PM
Tossing planes into the snow
Canada, BC, Smithers
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Quote:
Originally Posted by JumpySticks View Post
I haven't stiffened the fuselage though because I really want to keep the weight down for thermal flying.
The arrow shaft I put in the fuselage weighed exactly the same amount as the fiberglass stiffener that I removed. There was no weight gain, but a lot more response from the elevator and rudder. It's a win-win. Once you get that fiberglass thing out of there, you can feel how flexible it is.
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Old Sep 19, 2012, 09:46 PM
Drifting off the reservation..
JumpySticks's Avatar
USA, LA, Broussard
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Quote:
Originally Posted by Jovanx View Post
The arrow shaft I put in the fuselage weighed exactly the same amount as the fiberglass stiffener that I removed. There was no weight gain, but a lot more response from the elevator and rudder. It's a win-win. Once you get that fiberglass thing out of there, you can feel how flexible it is.
Ahhh....I didn't think about removing the FG stiffener. Good idea. Just the one that sits vertical near the bottom center? And that's where you imbed the shaft? I think there are two others beneath the pushrods, but those would be tough to remove I guess.
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Old Sep 19, 2012, 09:50 PM
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United States, WA, Spokane
Joined Feb 2004
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I too have been thinking that I ought to stiffen up the plane a bit. I think the aft half of the fuselage is the worse part of my plane. I was thinking some reinforced strapping tape applied under tension to each side would be a lightweight solution.

She's still a fine handling ship, despite the overall "foamy-ness". I was out for an evening flying session, but the air was dead, so I started practicing rolling circles. It was actually a pretty good plane for that; everything happens so slowly it's easy to make all the little corrections to make it look good. It is kind of funny though, such a big plane rolling about! Haha
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