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October 14, 2011


Paul B.

Question Paul,
I just cristend my clipped wing power up Racien,as I call it. My only concern is this. I instaled an E-flite POWER 10 on a Radian nosecone piece. The airplane flew grand at 1/2 throtle. If I tried to fly it faster on the throtl, it would nose down and refused tomaintain altitude. I went ahead and installed washers behind the bottom two motor mounts. Ihavent flown it yet,but the engine looks more inline then before. Question: is the offset caused by the 3 or 4 degrees of built in down thrust? Im assuming so. If so, will the same problem reappear on my other Radians that I modified with LARGER motors?

Paul B.

Just the usual question. I viewed the mod tapes and made them to my radian. Shes a joy to fly now. My concern is that I cropped 1 foot from either side of a second wing set so now my wing is 47.5 inches. I went ahead and installed FLAPARONS to it for more control. Im just curious. I installed a eflite power 10 to it, and cut 1.5 inches off of either side of the horizontal stab and elevator. I have it balanced at 3.25. I even added gear(tail dragger) so I dont have to hand launch it. Can you give me any advice as to what Im in for other than higher flight speeds and touchier controls. I even took it to the field today(didnt fly though), but was repeatedly told it now resembled a quicky 500 racer. TY.

Paul B.

I tried the mods and they work wonderfully. I also own a Radian Pro. Can I use the decalage mod on that aircraft?


I flew my new,rebuilt,restored,modified Radian yesterday. It flew like a dream! I will admit though, It tip stalled on the approach at about 50 feet because I was going slooooo. No sweat though. I added power and she recovered. She now flies faster, but still as an angel. Thanks again for a great mod(decalage angle reduction).

Paul Blais

I just had another thought(scary). I got to thinking about my modified radian. It wanted to desend. After some thought, I realize that it wasnt my stabalizer deflection correction, it was DOWN THRUST!No mater how much up trim I used, she wanted to decend. Im thinking that because of the downward pull of the motor, the aircraft took up diving. I've givin it some thought. I didnt see or even catch a glimps or wiff that UP THRUST should be added to compensate for the built in 3 degrees of down thrust. Im recieving a new fuselage on Thursday and Im going to modiufy it again PLUS add 3 or 4 washers behind the motor on three of the 4 bolts, to compensate for the down thrust. Personaly I feel that you should make it a point to advise other pilots/modifiers of the thrust correction. I think that it might just save a glider or two. That was just a thought, do with it as you will. NO HARD FEELINGS!, or landings:) Paul

Paul Blais

Thank you for the prompt reply. I will now admit, I tried my modified radian today. She flew,,,well, She flew. I ended up meeting the ground nose first from 71 feet(per my altimiter). I got slightly upset. BUT. i NOW HAVE A NEW FUSELAGE ON THE WAY, 3 SETS OF WINGS, AND A CANOPY. iM SET TO MAKE A NEW ONE. aFTER SITTING DOWN AND TRYING TO CALM DOWN, i REALIZE WHAT THE CAUSE OF MY "INCIDENT" WAS. i HAD PUT APROX 7 OR 8 MM DECALAGE ANGLE ON THE STAB. i DIDNT REALIZE THAT ONLY 1 OR 2MM WOULD HAVE SUCH AN EFECT. tHE PLANE ONLY WANTED TO DESCEND THE ENTIRE FLIGHT. iVE BEEN THINKING. i MIGHT DO THE STAB ANGLE AGAIN BUT ONLY 2 OR 3 MM. wILL THAT RESULT IN A large NON CLIMBING tendency? although I realize she will still have a climbing lust.

Paul Blais

I just finished rebuilding my Radian. A wind gust got under the left wing and flipped her into the ground upon my last launch. My question is I have since made your mods to it and am curious as to how she will handle. Will she be faster, more responsive, more stable, or? I bought a second and third set of wings. I added FLAPARONS to one set and built the other one with no mods. Im curious as to how the fuselage will react. I changed the decalage angle so that will remain a constant change for all of the wings(flaparons, no mods, a super short 4ft. wingspan cropping with ailerons). Any comment will be appreciated.
OHHHHHH YEAH, the CG is 3 3/8" back from the LE.


No need to worry about that forward pivoting. At, say, 4000 rpm, your blades will experience over 800 g's (!) at the tip. Only over 400 g's halfway out. I suspect that's enough to keep the prop open when it's spinning.

In my experience, the Graupner 10 X 8 will get you to 200 meters in time. And it will make your motor last longer.

Larry Bradford

I received and installed the Graupner 11/8" prop today and it pivots 30 degrees forward beyond being 90 degrees to the motor shaft. Have I got the wrong 11/8 prop (1329.28.20) &/or do I need a different prop mounting hub? Yes, I had to drill the attachment pin holes larger to fit the standard pins. No big deal.


The plywood support is inserted into the tail, a slot is cut centerline from the top, then the support inserted,fitted and then epoxied in. THe side view photo shows the postion of the brace once inside the tail, no glued to the side. - PN

Alan Heller

You mentioned in your video about adding 1/32 plywood to the tail. Is one side good enough or should it be added to both sides? I have two Radians and just bought a Radian Pro. I am using one of the Radians for your mods. Hope to have them ready by the time this cold weather breaks!

DeForest Mapp

I taped my entire Radian with scotch wrapping tape.(Wings and all)I have not had the chance to fly it because of the weather. Do you think this will improve performance and durability?

Tony Fry

Do these decalage etc. mods hold good for the Radian Pro. as well?

cheers Tony Fry


I've had a hoot with mine, and flights over 1.5h, but always on a slightly puffy, now 2 year old stock battery.

Can anyone speak to making one of the batteries that's aftermarket fit the EC3 connector?

I love duration and would love to do a 2h plus flight...thanks in advance.

David Sciortino

Thank you Paul, for sharing your mods with us.

Any recent updates or amendments to share, before we start cutting, melting, taping, and gluing?


I did the mods you suggested and now it wants to point down a lot..

Did you use the same spinner or is that an upgrade too?


For the last two comments:
yes, change the decalage angle of the tail IF you know what that angle is by measurement. If your decalage is beyond one degrees negative (up angle to wing) then you must change the tail angle as the CG goes back. As I say in the video, tail power increases as CG goes back, making any decalage angle amplified.

As for the prop, the 11-8 has a wide shoulder that needs to to be ground down to fit the stock Radian spinner and pins. It should fold back fine, you can trim the spinner openings if they bind.



Hi, thanks for that info, iv done a few of the mods to mine now, iv not had time to try it out yet though..

One quick question if you dont mind, the 11x8 prop.. did you have to change the spinner? i have these props but they dont fit in the spinner and if they did they wouldnt fold flat to the fus.. maybe you use a different part??

Thanks again for everything..


I just read your very informative article on improving the Radian glider. I started building models in1956 and built many from 1/2 A to many 1/4 scale. Now after 25 years of not building I want to get back into flying again. I purchased the Radian and soon found the weak tail assembly. I fiberglassed the the rear fuselage and part of the fin with 1/2 oz. glass and eze-kote. It did a great job of fixing the tail. I will incorporate your other excellent mods. The question I have is that should I modify the stab. incidence as well. I am again just a beginner flyer and for learning to fly again should I modify it or stay with the original position and CofG and maybe modify it later after I have more stick time.

Bob Center

For my Radian I made a short wing (1.5 m), and a long wing (2.5 m) out of two stock wings. From one stock wing I cut a ..25m length out of the wing, just inboard of where the downwash begins. Removing the .25m chunk and gluing the "tip" to the "root" gives the short wing.

Cut the other stock wing just inboard of the downwash, and insert the piece taken out of the other stock wing.

I used a chop saw to ensure precisely square cuts; foam-safe gap filling super glue; and "Scotch Tough" transparent duct tape. This tape is great for all sorts of construction e.g. tailboom and wing stiffening, leading edge hardening and repair, e.g warping the tailboom to compensate for crash-induce fuselage deformity, so that yaw trim is not necessary. A great feature of this tape, particularly with white foam, is that it is pretty much invisible, or actually improving appearance by lending a smooth sheen.

Try it, you will like it.

Aeronautical engineering, design, and airframe mechaniching complete, we went to the cow pasture next door for flight tests.
The really cool thing is that the flights turned out as well as I had imagined.

As I thought might be the case, both flew OK with trim settings for the stock wing. T

Test flights with both wings were all successful; short wings had a much quicker roll rate, faster glide. Short wings seemed to climb more quickly at the same power setting.

The long wings seemed to increase sensitivity to elevator control input.

I look forward to thermaling the big wing and slope soaring the small wing.

I have not decided whether or not to change the decalage and move the CG aft. The higher aspect ratio will cause the plane to stall earlier; would moving the CG aft exacerbate this?

Also, it seems that a forward CG will provide better slope soaring stability and responsiveness, using the short wing.

Bob Center

P.S. Early on I got tired of digging cow pie and dirt out of the nose cone, and built several versions of light weight wheels that work well and could be better if I could find some titanium wire. I have slope soared with the wheels on, but I am not sure that thermalling would be possible with the wheels. I do not use them much anymore, but they are usefull if you are working on improving your landings.

If you would like photos of any of this stuff let me know and I will post (how do I do that?) or send them.

Jack Reed

...some times you get "stupid" lucky...ball hits tree,falls on green,sink putt for birdie etc,etc. I saw flex in the fuselage on early vids and bought 2 carbon strips which I ca'd to the fuselage from the motor mount to the tip of the tail[armor belt like on an old armored cruiser]which makes mine very crash resistant...looking at the wing in the store I could see that lengthening,the span would be possible. This makes the glider look [at least] like a sailplane...My new spars are made out of "rifle" shaft golf clubs because they are not "graduated" from grip to tip.Snow sticks inner sleeve the stock spar for joint strength.Bushings made out of graphite golf shaft preserve the integrity of the wing root...I added extra surface to the rudder,about 1/2 inch wide to increase directional control with my 3-meter wings at low airspeed...see my set up posted last year in my utube vid...Having a great time with my Kodac Playfull mounted in the back of the cockpit with the wrist strap looped around the strut and "X"ing rubber bands around the fuselage and canopy where it sits...don't know how much it weighs but this baby will penetrate and it flys faster in glide than bald eagles and hawks,seems slower than sandhill cranes when they are "cruising"...could not keep up with them in the Logan VOR looking forward to this fall when they migrate through the Cache Valley...go to patcojack for my utube posts.radian rc monster wing will get you to a seperate vid from 2 years ago.

Chuck Hough

I use the 2200 ma LiPo and have had very good sucess with them for many years now. I have two of the Zippy and a couple of others that allwork well, but the zipppy's are still the best ones I have and are about three years old now so they too are getting a bit on the weak side. the 25C rating is good, so maybe I will get a couple more to replace the tired ones this year. Mu oldes ones are five and six so they are about ready to go, but so far they are still holding up, so I will have to see how they go this year and make a judgement at that time.

Chuck Hough

I too fly a Radian and a Radian Pro and have had good luck, but the Radian seems to be my favorite flyer as it seems to be easier to get into the aif and keeep it up there for as much as an hour or ma be more. I love both of them butg it is the Radian that I fly the most. It seems t be the only one I would need to but again if I ever need to. The Pro seems to fly good, but it is the less preferede one right now.

Bryan Freund

Ive flown several models the last few years ,the radian is my 1st powerglider.i also was anxious to do all the mods,the insert can be cut with a razor saw from ace or where ever,nice for adding stringers and such to foamies anyway .I changed the decaleage as posted but cant say i prefer it,but its been in extreme winds ,in facy the canapy cover blew off and the battery got kicked out,it held and landed it.but my elevator lincage broke too,absolute junk,i put a z bend in it for nor thats limiting my up elevator a lot i need to fix,but on a nice day almost stock i easily get 1/2 hour flights ,even in rathe heavy winds,but last flight it was seriousy gusty,very tricky to land,even in my huge strenghten the fuslage as suggested i used bondo and carbon fiber ,but id do as suggested and fly it mainly stock for a while,its quite the fun bird ! i was anxious to switch the decalage as it does baloon badly stock,but trim her out and enjoy.


also check

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