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Old Feb 01, 2013, 09:43 PM
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Unfortunately I only know how to do it on 9503, that has glider programming, something that dx8 has sadly missing. I saw it done on DX7 on a Cularis somewhere on RCG but that one is quite different to dx8.

here is a sample of Dx7 programing, wow
http://www.rcgroups.com/forums/showp...&postcount=833

Quote:
Originally Posted by socommk23 View Post
i have a dx8. ive tried to get it to wor as discussed but the flaps would not play ball. they would go down with an aileron but not up. then one would go both ways the other only down.
gave up.
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Old Feb 03, 2013, 03:06 PM
xjh
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Originally Posted by cliffkot View Post
Ultimately that is what you are trying to achieve. The decalage mod eliminates the need for down trim once you get your CG aft of the stock position. (Paul Naton says the same thing in his PT DVD.) Of course a zero trim condition will reduce elevator drag, but I found on my Radian at least that with CG at 3 1/2 inches I only had about 1.5 mm of down trim without the decalage mod. I hardly think that little trim would affect the overall performance of such a slow glider.

That said, I've done the decalage mod on my new Radian just to find out how much the performance changes.

Cliff

PS To anyone considering changes to the stock Radian, you will find that the bird is amazingly different once you move your CG rearward of the recommended position. Do it slowly to get used to how she flies. You don't have to do the decalage mod to get the benefit. Decide on the mod after you get the CG to where it feels right. If you then have a lot of trim that you'd like to eliminate, and you feel like doing some cutting, then have at it.
Hi, it is not the reduced drag of the tail that improves the glide performance, but the reduction in induced drag of the wing as the a/o/a is lowered and its L/D ratio is moved on the curve. The glider with the new settings is slightly faster and thus penetrate better. The tail plane mod ,of course reduces the tail plane drag so some benefit is garnered.
Using the Robart incidence meter on an under cambered foil is at best an approximation of the airfiols camber line. Having said that in aerobatics, with symmetrical air foils (with the the camber line a straight line from LE toTE 1/2 way between the top and bottom surfaces and the Robart meter reflecting this) between 1/2 and 3/4 of a degree is the necessary longitudinal dihedral necessary to obtain sufficient lift on the main plane. Richard
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Old Feb 08, 2013, 10:26 AM
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Ak Eagle's Avatar
Alaska
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Prop Change

Is there any problem using the Graupner 10x8 prop with the 6mm shoulder vs the 8mm shoulder?

Thanks,
Rick
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Old Feb 08, 2013, 04:09 PM
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Quote:
Originally Posted by xjh View Post
Hi, it is not the reduced drag of the tail that improves the glide performance, but the reduction in induced drag of the wing as the a/o/a is lowered and its L/D ratio is moved on the curve. The glider with the new settings is slightly faster and thus penetrate better. The tail plane mod ,of course reduces the tail plane drag so some benefit is garnered. Richard
I beg to differ. It is the COMBINATION of the stab and the elevator that set the angle of attack of the wing. A change in stab incidence alone is not the whole story.

For a fixed stab incidence, the aoa of the wing is set by the elevator angle. Changing the elevator moves the plane along the polar curve. See

http://www.5c1.net/Glider%20Performance%20Airspeeds.htm
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Old Feb 09, 2013, 07:49 AM
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I just want to confirm...we are still talking about the Radian...not the Radian Pro? I'm getting a little lost. Thx
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Old Feb 09, 2013, 10:43 AM
Tossing planes into the snow
Canada, BC, Smithers
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Originally Posted by 6Sally5 View Post
I just want to confirm...we are still talking about the Radian...not the Radian Pro? I'm getting a little lost. Thx
I think that most of the posts are referring to the standard Radian, and when people talk about the Radian Pro, they usually specify Pro or RP. Are you wondering about the decalage mod in particular, or the other things that are discussed here?
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Old Feb 09, 2013, 10:59 AM
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Quote:
Originally Posted by williamson View Post
I beg to differ. It is the COMBINATION of the stab and the elevator that set the angle of attack of the wing. A change in stab incidence alone is not the whole story.

For a fixed stab incidence, the aoa of the wing is set by the elevator angle. Changing the elevator moves the plane along the polar curve. See

http://www.5c1.net/Glider%20Performance%20Airspeeds.htm
Agreed except that there is a third variable - the CG. The wing can be placed at the best L/D AoA by any combination of the three variables.

If we want to maintain a certain CG placement and have a neutral elevator to minimize drag then stab incidence is the lone remaining variable, which is the principle behind Paul Naton's decalage mod.
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Old Feb 09, 2013, 04:15 PM
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Originally Posted by Ak Eagle View Post
Is there any problem using the Graupner 10x8 prop with the 6mm shoulder vs the 8mm shoulder?

Thanks,
Rick
On what hub? The 6 mm shoulder fits the stock hub but you have to drill the holes out to 3 mm to accept the pivot pin and slip in a couple of washers. You can use the 6 mm shoulder on a hub made for 8 mm props if you put washers/spacers in to fill the gap.
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Old Feb 10, 2013, 09:36 AM
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Quote:
Originally Posted by Jovanx View Post
I think that most of the posts are referring to the standard Radian, and when people talk about the Radian Pro, they usually specify Pro or RP. Are you wondering about the decalage mod in particular, or the other things that are discussed here?
Thanks Jovanx...being brand new in gliders, I'm not familiar with terminology you guys are tossing out. It's a whole science and new world for me, so it's like learning Spanish by hanging around in Mexico, lol!
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Old Feb 10, 2013, 11:01 AM
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Quote:
Originally Posted by 6Sally5 View Post
Thanks Jovanx...being brand new in gliders, I'm not familiar with terminology you guys are tossing out. It's a whole science and new world for me, so it's like learning Spanish by hanging around in Mexico, lol!
Most of the talk about radio mixing is probably referring to the pro but most of the decalage discussion an apply to both it's just that the starting points might be different. my RP tail seems stiff enough and I haven't had any issues with the stab incidence. most of my mods were with the wing servos/hinges to get a full crow deploy and then working with props for the climb. The CF wing spar helped stiffen the wings and I assume it would with the Radian also
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Old Feb 10, 2013, 12:05 PM
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Alaska
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"On what hub? The 6 mm shoulder fits the stock hub but you have to drill the holes out to 3 mm to accept the pivot pin and slip in a couple of washers. You can use the 6 mm shoulder on a hub made for 8 mm props if you put washers/spacers in to fill the gap."

Thanks Kaptondave

Rick
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Old Feb 10, 2013, 12:25 PM
HaoleboyRC
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United States, CA, Auberry
Joined Apr 2009
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Better props

Hi guys,

I subscribed to this thread a while back and thought I would add what I found on props to improve performance. I put a 50mm aluminum spinner from HK on my Radian and it came with 3 collets so it can accomodate different size motor shafts. I am using a Graupner 11x6 (8mm shoulder so will not work with stock spinner) cam set of props and using a watt meter get around 200 watts with a 25c 3s 1300 mah battery. The same setup with the stock blades only pulls 150 watts. I then found a set of props at Value Hobby on their prop page and they are listed as 10x8 and have a 6 mm shoulder. I had to drill them out to number size drill bit 31 I believe or maybe 30 to work with no slop. Start at 32 and check after each size change. The Graupner blades worked very well and cost about $16.00 with shipping to get here in California. The props from Value Hobby cost $3.52 and shipping and total cost per set is less than $5.00 and they pull 220 watts on my watt meter. They pull 22 amps where the Gaupners only pull 19 amps so maybe not quite as efficient but a little stronger pull with 10x8 blades. I get 200 meters in just over 20 secs I think about 22 secs as close as I can tell. So for cost and fast shipping I use the Value Hobby blades. All of the guys here in our club Fresno Soaring Society are running these blades and we get 5 to 7 climbs per battery charge from this setup. I am using a Turnigy Nano Tech battery and it is rated at 25 to 50C. I just got some 45 to 90C rated batteries and have not really found out how long they will last and it is cold now but I think they make that climb with everything else the same about 15 secs. Hope this info helps some of you.

HaoleboyRC
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Old Feb 10, 2013, 12:37 PM
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I did a similar thing with my Radian Pro and posted my results over in the Radian Pro thread. Here's a copy of my findings. The part numbers are the HK prop blades I used. I have since gotten a GPS logger and will add a rate of climb column in the spring when I get back outdoors to fly
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Old Feb 10, 2013, 01:08 PM
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When you see a price difference as large as that between the Graupner and Value Hobby props there is usually a reason for it. The Graupner props are reinforced with carbon fiber. The Value Hobby props are nylon. If the cheap ones work for you that is fine but the two blades are not equal in quality.

I have tried the aluminum hub and spinner (Cermark) but found them to be significantly heavier than the stock plastic ones. In my case the added weight could not be balanced by moving the battery as far back as possible so I had to add dead weight to the tail. The total weight penalty using the aluminum hub and spinner was 1.7 ounces. While appreciating that the aluminum is stronger I did not feel it was worth it so went back to the stock spinner. I have been flying the same one for 2 1/2 years with no problem.

With both the props and the hubs there are trade-offs involving strength, weight, performance and cost. Each individual must assign weighted values and decide what is best for him.
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Old Feb 11, 2013, 02:51 PM
HaoleboyRC
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United States, CA, Auberry
Joined Apr 2009
135 Posts
Props

Hi KaptonDave,

Did not mean to indicate in my post that the props were equal only that they are a great improvement over the stock blades which I believe to also be nylon. After doing the mods on my tail I could use the weight of the HK spinner to move my CG back forward a little as I did not like it at 3 1/2 + so am using the HK spinner and the Graupner blades on my Radian and I also shortened the nose so that is why my CG shifted to the rear. I do believe I said that the Graupner's had a little less amp draw and still climbed as fast or close to it but they won't work with the stock plastic hub. Hopes this removes any bad thoughts I may have put out there for someone. The EMP blades do work very well however.

HaoleboyRC
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