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reed-valve stunt

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reed-valve stunt

Post  roddie on Thu Oct 09, 2014 10:59 pm

A challenge.. Can a pattern be flown using a reedy? This Winter, I'd like to build a 1/2A C/L stunt airplane, using the mounts I made for the "290" (postage-stamp) prod. engine's backplate.. and an external fuel tank of some sort. A "Horseshoe" back-plate would suffice as well. The tank would need to hold enough fuel initially for experimentation. I used to fly my 1/2A models on less than 30' of line. I also use to experiment with 7 and 8 inch diameter propellers. A decent Cox .049 reedy will (barely) 2-stroke on an 8 x 4 "Zinger" wood propeller using Sig Champion 25 fuel. (try it..) I used to fly a considerably heavy biplane with this combo.

I had very limited space in which to fly my airplanes at the time... and was flying them on 25-30 foot lines. An airplane built around a competent "stunt" design, "might" fly slow enough on short lines with a big prop... to provide some fun stunting.

Any thoughts on this?
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Re: reed-valve stunt

Post  JPvelo on Thu Oct 09, 2014 11:14 pm

Here's a bad video of a poorly flown beginner pattern with a reedie lol! :
https://youtu.be/SvEpZuh9wNs


Last edited by RknRusty on Fri Aug 12, 2016 8:52 pm; edited 1 time in total (Reason for editing : Tried to fix Youtube link)
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Re: reed-valve stunt

Post  Brenda on Thu Oct 09, 2014 11:23 pm

JPvelo wrote:Here's a bad video of a poorly flown beginner pattern with a reedie lol! :
Ear spliting! Love it.
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Re: reed-valve stunt

Post  Cribbs74 on Thu Oct 09, 2014 11:26 pm

I have plenty of thoughts!

First off, yes a reedie can do a full pattern. It would take some setting up and a capable plane, but it's very possible. If you are serious then contact Jim Roselle (JPvelo) and he can get you started in the right direction.

No Cox engine is designed to do a 4-2 stunt run. While it is possible to make the engine run that way it won't make enough power during level laps and stunts will be entered into going too slow and you will have tension issues.

Speed is the name of the game in 1/2A stunt. You can pitch down on props to slow things down, but it will still be quicker than the usual 5.5 sec lap times the larger ships do.

Forget large diameter props, they do work as in the engine will turn them however, you rob so much power that again your stunts will be hampered. You need to stay in the power band to be successful.

You can play with line lengths to get the speed to where it's tolerable, but it will always be fast.

There is a lot to consider, but like I said it can be done. If you want to learn how to stunt at a reasonable pace then I would suggest you finish the Ringmaster and learn with that. It will get you started.

I have met many folks that have flown CL for 50yrs and still can't do a loop in fear of crashing. That is something one needs to come to grips with. If you read some of my posts from a few years back you will see my plight in learning. I went through a lot of planes. Then I flew a Ringmaster and all that started to change. I still crash from time to time, but that is mostly caused by engine trouble or learning a new stunt.

Anyway, that's not what you asked I suppose. If I were you I would just fly something and get your feet wet again and go from there.

Ron





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Re: reed-valve stunt

Post  Theo Kleynhans on Fri Oct 10, 2014 1:16 am

I guys

Sorry to ask this again, but could you also post the link on the video please. I would like to see this pattern with a reed.

My server is blocking it the way they are posted.

Thanks

Theo
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Re: reed-valve stunt

Post  JPvelo on Fri Oct 10, 2014 1:29 am

There's really not much to be seen but here it is:
http://youtu.be/SvEpZuh9wNs
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Re: reed-valve stunt

Post  Theo Kleynhans on Fri Oct 10, 2014 1:30 am

Thanks Jim.

That was quick
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Re: reed-valve stunt

Post  roddie on Fri Oct 10, 2014 8:52 pm

Cribbs74 wrote:I have plenty of thoughts!

First off, yes a reedie can do a full pattern. It would take some setting up and a capable plane, but it's very possible. If you are serious then contact Jim Roselle (JPvelo) and he can get you started in the right direction.

No Cox engine is designed to do a 4-2 stunt run. While it is possible to make the engine run that way it won't make enough power during level laps and stunts will be entered into going too slow and you will have tension issues.

Speed is the name of the game in 1/2A stunt. You can pitch down on props to slow things down, but it will still be quicker than the usual 5.5 sec lap times the larger ships do.

Forget large diameter props, they do work as in the engine will turn them however, you rob so much power that again your stunts will be hampered. You need to stay in the power band to be successful.

You can play with line lengths to get the speed to where it's tolerable, but it will always be fast.

There is a lot to consider, but like I said it can be done. If you want to learn how to stunt at a reasonable pace then I would suggest you finish the Ringmaster and learn with that. It will get you started.

I have met many folks that have flown CL for 50yrs and  still can't do a loop in fear of crashing. That is something one needs to come to grips with. If you read some of my posts from a few years back you will see my plight in learning. I went through a lot of planes. Then I flew a Ringmaster and all that started to change. I still crash from time to time, but that is mostly caused by engine trouble or learning a new stunt.

Anyway, that's not what you asked I suppose. If I were you I would just fly something and get your feet wet again and go from there.

Ron






Thanks Ron! Yes.. I have all these LARGE airplanes/kits here... and have never flown anything larger than 1/2A. I'm hoping to get the S1 built this Winter.. but my workshop is small and terribly cluttered.. or I would have also started on my "Voodoo" that Lieven so generously sent me templates/updated plans for.

I "do" understand what you're saying about the "usable" power-band of an .049 reed-valve engine. What I thought "might be" attainable.. is the combination of a "small/light enough" model to overcome the loss in power from using a larger prop.. along with unusually short lines... to be able to stunt in the small area that I have in my side yard here at home. Yes.. it still may be too fast.. even with the engine "lugging".. but that's something that I wanted to test. I also found that using the "larger than normal" props almost doubled the engine's run-time.. so a fuel tank won't have to be very big.. maybe 1/2oz. I'm planning a small "built-up" wing with a fairly thick/fully symmetrical airfoil and short tail-moment for the initial test. Possibly building-in generous amounts of engine/rudder offset could help to slow the model down too. The planned lines will be less than 25 feet long for what I have the room for.. here at home. It's my "crazy nature" to try something unorthodox... or that the odds are against. I've had my share of crashes. That's the only way to learn.. and I'm also going to try to adopt Mark's "BTC" concept into the design.. The built-up "wing" will be the challenge there.. but I have something already in the works; that I hope will build quickly, and still be light and strong.
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Re: reed-valve stunt

Post  pkrankow on Fri Oct 10, 2014 10:38 pm

A bee with a 6-4 rubber ducky prop is a lot of fun. With a more rigid prop go with the 6-3. Keep the plane sub 6 oz and it can do quite a bit.

I am still not convinced that the 5 inch prop is turning enough more revs to make up for the area of the 6 inch prop... but I have seen it is a plane by plane basis. The larger prop works better on a lighter plane.

Might as well also take a KB backplate and a texas timer nva to run on bladder while you are at it.

Phil
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Re: reed-valve stunt

Post  roddie on Sat Oct 11, 2014 11:56 am

pkrankow wrote:A bee with a 6-4  rubber ducky prop is a lot of fun.  With a more rigid prop go with the 6-3.  Keep the plane sub 6 oz and it can do quite a bit.

I am still not convinced that the 5 inch prop is turning enough more revs to make up for the area of the 6 inch prop... but I have seen it is a plane by plane basis.  The larger prop works better on a lighter plane.

Might as well also take a KB backplate and a texas timer nva to run on bladder while you are at it.

Phil

Thanks Phil. This is actually a candidate model for the .018" thick phenolic skinned "monocoque" tube-wing that I'm working on. I'm at the "fixturing" stage currently. The CAD software/CNC router that I use at work, will allow me to design/cut ribs and external rib templates to form the leading edge.. just back to the spar. The templates (probably 4 of them) will be mounted rigidly to a board equally spaced to the wingspan.. and the bottom of the phenolic sheet will be tacked to this board with the spar and tip-ribs having been glued in place to the bottom skin beforehand. The spar and tip-ribs are not structural.. but are for establishing the airfoil-shape/thickness only. The strength will be in the skin. It's a crazy "Roddie" experiment.. but I'm going to try it!
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Re: reed-valve stunt

Post  roddie on Fri Aug 12, 2016 7:20 pm

Well.. here's one of my old threads.. check-out Jims' (jpvelo) nice control of a small c/l reed-valve stunter. Not sure what the model/engine/fuel/line-length/prop combo was... but it was a sweet flight!

I started this thread, because I was interested in trying to build a reed-valve stunt model. I still want to build an .049 Cox reed-valve powered model for use in a very small area... being my side yard which is quite small. I have approx. 40' of clear area in which to fly. This is more geared toward an .020 sized craft.. but I don't have engines that small. I'd really like to fly "here" at home.. if possible. The aircraft will need to be designed to turn on a dime.. but not fly so fast that I can't control it. I have several Cox 6" x 2" L/H props to experiment with.. which I think might help keep a stock .049 reedy pulling steady.. along with the advantage of the added line-tension that a L/H rotation prop provides. I'm thinking about building a small 18" w/s close-coupled slab-wing airplane that will perform in a small diameter circle. I hope to keep the speed "down" and the power "up". I have this next week off from work... and hope to put a model together to at least try.

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Re: reed-valve stunt

Post  RknRusty on Fri Aug 12, 2016 9:20 pm

roddie wrote:...I started this thread, because I was interested in trying to build a reed-valve stunt model. I still want to build an .049 Cox reed-valve powered model for use in a very small area... being my side yard which is quite small. I have approx. 40' of clear area in which to fly....
So 20' from pilot to edge means you're talking 15' lines, is that about right? based on that assumption, if the Cox 6x2 is too much load for the engine to have the steady power, try an APC 6x2. It's still going to be faster than your preferred stunt speed, but you've gotta start somewhere. While you're getting the feel of it, you might think about building another plane with a bigger wing area and a blunter fatter airfoil. A little heavier and draggier with lots of lift for tight maneuvers that can be flown with a shorter prop. Seems like bigger props result in bigger turns than small props. If it's heavier with an adequate wing, you can move the CG aft and still get the snappy turns. I'm interested to see if others agree or not with that assessment. Flying in a half sized circle is the greatest challenge to getting your plane set up to do it.
Just guessing.
Rusty

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Re: reed-valve stunt

Post  JPvelo on Fri Aug 12, 2016 9:57 pm

Roddie,

I would build a Lil' Satan and put the prop on backwards to slow it down. I have plans for
A Bill Netzband designed slab wing reddie combat thing I will dig out tomorrow and send pics of if you want.

Jim
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Re: reed-valve stunt

Post  batjac on Sat Aug 13, 2016 12:02 am

Roddie, way back when I joined this forum and built my first C/L plane in 40 years, it was my little blue and white Baby Ringmaster.  I couldn't do more than roundy-roundy with a few loops (kinda like now...), but I took it over to Delta Park and let the 1/2A guru there fly it.  He was able to do all the pattern maneuvers, so I can say that a reedie powered Baby Ringmaster CAN do it, if the pilot can do it.  A killer bee clone would do it nicely.  My Baby Ringmaster came out at 6.1 ounces with heavy Monokote wings and fuse, so it could be built lighter with a dope finish or one of the light iron on films.  Looking back at the planes I've built recently, I don't understand how it weighed so much, but again, it was my first build coming back.

Here 'tis




And with the Beginner Ringmaster:



Wow! I built those things just over 3 years ago!  What a time it's been here on the forum!

The Noob Mark
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Re: reed-valve stunt

Post  getback on Sat Aug 13, 2016 9:17 am

I agree with the Baby Ringmaster although I have not flew mine yet I think would bee the best choice for getting started back and working toward the beginner pattern or just getting in the air in that short distance . The scratch build is not too bad a build , slap one together , rattle can that baby and go fly with one of your red Bee mount engines if not experienced in bladder balloon tank , use a stunt tanked Bee as not to take time figuring just to get in the air . Would Love to see you get some flight time in Roddie it will do you good Eyebrows I am going to have to put another engine on mine as I don't like the way this one on it runs ... Eric This Site Rocks!
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Re: reed-valve stunt

Post  roddie on Sat Aug 13, 2016 12:04 pm

Thanks for the comments guys.. I really appreciate it. I recently went on a med for depression/anxiety. I hope it helps me, but it takes a while to work.. and usually makes you feel worse for a bit. Not my first time on a med.. but it's been several years since I've gone that route. I have a family history (both sides).. so it's a chronic thing, along with situational. It's been holding me down with everything for a long time. I've never liked the idea of taking meds for this condition.. but I'm tired of the stifling grip that it's had on my life. Hard to understand if you haven't lived it. With me it's a constant cycle of ups and downs. The "ups" get me excited initially to start a project.. then the "downs" stop me in my tracks with feelings of anxiety. It's a debilitating disease.. and embarrassing for me.

I figured that (I often figure that..) a new model project will jump-start me back into sync. I look at all my projects previously started.. and think; "no.. that's too complicated".. or "that was a dumb idea to start with." Part of that problem is my desire to build models of my own design. I used to be able to do that.. finish and actually "use" them.

Flying something (C/L) would really help I think.. but I've had anxiety toward packing stuff in the car to go off somewhere and fly by myself.. I always think of reasons not to do it.

Back to my thread-bump.. 17' lines and .049 reedy for power.. Huh... I'll have to slow the model down for even just roundy-round.. Maybe some of my ARF's would be candidates. I could launch with a super-rich needle just to get back used to flying. Maybe the Cox PT-19 for starters.. with the firewall set on beginner and the 6" x 2" LH prop that it came with.

Thanks again for the encouragement! Thumbs Up



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Re: reed-valve stunt

Post  rsv1cox on Sat Aug 13, 2016 12:52 pm

roddie, your the same age as my middle daughter, her sister turns 60 next year and they both require meds similar to yours. My wife and I grew up in the forties and fifties and graduated together in 1955, a whole different world from yours and theirs. Our class was just one big (25 students) happy family. Their classes not so much due to the complexities of the times. Perhaps you experienced the same tensions during your formative years that they did, only thing I can think of that relates despite your family's history. I have read that there are entire towns that are hooked on Prozac. We sent our younger son to a private school to avoid those complexities and well, the kid turned out "normal" whatever that is.

But I would think that playing music in front of a crowd takes a lot of talent and courage, something that you obviously have. When I had to speak in front of a group of people my knees would turn to jelly.

For me building models at this stage is enough, it's fun and stimulating. I would love to be able to fly them but for me that's secondary. Do what makes you happy and damn the torpedo's.

Bob
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Re: reed-valve stunt

Post  getback on Sat Aug 13, 2016 1:55 pm

Yeah that was me with the Greenie lol and I have myself been down that F-ing road and made things worse in the long run FOR ME ! you bee careful young man ,, NOW back to subject .. well you have more than 3 models soo test a engine put on model and launch almost WAO so you don't struggle with getting in the air ==== if I were closer I would bee there for you and you know that BUT< , [bleep] round and round is GOOD !! that's what I do for now Huh...  I want let up this time till U DO IT Friend ( make it happen and I will send you a prize ) Hows that ? Bob the whole town DAMMIT! man that's crazy ; // Here Roddie just for a good laugh**     https://www.youtube.com/watch?v=54gzhqiPC9U  I look like a toy on a string myself lol!
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Re: reed-valve stunt

Post  JPvelo on Mon Aug 15, 2016 3:23 pm

Roddie,

Here's the plan I promised, a little something for the pipe bomb lovers out there. Says right on the plan "will perform all AMA precision aerobatic maneuvers". Build it in a couple evenings and hit it with a light coat of duplicolor clear enamel.


Root chord 6"

Tip chord   3.25"

Stab root   1.5"

Stab tip      .25

Elevator     2"

Rudder height 2"

All other measurements are on the plan.
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Re: reed-valve stunt

Post  roddie on Tue Aug 16, 2016 5:38 am

JPvelo wrote:Roddie,

Here's the plan I promised, a little something for the pipe bomb lovers out there. Says right on the plan "will perform all AMA precision aerobatic maneuvers". Build it in a couple evenings and hit it with a light coat of duplicolor clear enamel.


Root chord 6"

Tip chord   3.25"

Stab root   1.5"

Stab tip      .25

Elevator     2"

Rudder height 2"

All other measurements are on the plan.

Thanks so much Jim! I've been wanting this plan! I believe that it's called the "Ambush".. the model that Allen Brickhaus was teaching that group of kids ("The Patton St. Pirates"?) to fly before he sadly passed away in 2013.

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Re: reed-valve stunt

Post  roddie on Wed Aug 24, 2016 2:34 pm

I had some thoughts on giving a "bathmat-stooge" a try. As I mentioned.. I'm going to attempt flying in my side-yard with short-lines. The primary model candidate will be this little self-designed airplane which has never seen any airtime since I built it in 1993.



It has a 20" span 5" chord (100sq.) 1/8" balsa sheet-wing. The firewall is sized for a horizontally-mounted Cox horseshoe back-plate. Weight with this .049 reedy engine configuration right now is 4.9oz. (less tank). The tip-weight is a hefty .25oz. to offset the weight of the solid lead-outs which are .031" music-wire. I can easily swap-out the Perfect metal bell-crank and lead-outs, and substitute a Sig 1/2A Nylon bell-crank and .015" solids. There is an adjustable lead-out "comb-type" guide that I wouldn't use any type of braid with.



That's an .005" sheet-brass comb. spanning 80% of the tip-chord and has a strip of 1/8" sq. balsa glued to the wing, as a "backer" for the comb.. but more so to lock the lead-out position captive. The comb is detachable via screws. Removing one screw and loosening the other; affords a "hinge" to lift the comb to alter the lead-out position. The 2-56 screws thread into t-nuts set into "popsicle-stick" supports glued into the wing.



That guide-arrangement doesn't weigh much, for what it's designed to do. I'm proposing a 2-blade 6" x 2" L/H prop for the first flight. Hoping to keep the weight right around 5oz. "with" the 6cc wedge-tank that it was built around. The tank's position is on the model's theoretical c of g. I might not need much (if any) outboard tip-weight, running the L/H prop.. we'll see.

At the time I built this model.. I was experimenting with "cored" sheet-wing construction. Where you see the blue mono-kote strips; there are 1" X 7" cut-outs. Strange.. but it does trim some weight with the short nose-moment. The firewall is dead-straight.. but the rudder/fin has a few degrees of offset.

As with most of my designs, I did draw-up some plans. It's not complete.. but the outlines are there. I'll post what I drew in 1993 in this thread. If anyone's interested in building it.

https://www.coxengineforum.com/t6164-roddie-s-combat-model-for-reed-power?highlight=roddie

It's a quick-build.. other than the lead-out guide design.. but that part of it would be up to the builder to duplicate. I'll be glad to provide any extra info.. and will "update" the plan to include the missing measurements/illustrations and pertinent construction data. The "unofficial" name of this model is the Rodbat.
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