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Old Jul 23, 2012, 10:30 PM
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United States, TN, Knox
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HK Ryan STA EPO build

Hi!
While waiting for the ParkZone UM Spitfire to be released, I became frustrated with the unceasing delays and decided to get a model of one of my all-time-favorites, the Ryan ST/PT.
Next question was: which model to buy or build? I've only ever flown ultra-micros, including the HZ Champ which is like a wonderful old shoe, the T-28 Trojan which really does fly very well and may be a good cheap introduction to 4-channel flying and the F4U Corsair, which gives me all manner of trouble and whose characteristics seem to change every time I fly it. It's been crashed and repaired so many times I'm fairly certain the CG is off and it's a fair bit heavier than when new.
And the UMs are so very wind sensitive I thought I'd like to try something with more heft and power.
I saw the Ryan NR-1 Recruit at the National Naval Aviation Museum in Pensacola and was smitten. See attached photo. Then I saw Banana Hobby's you tube demo vid of the STA model and decided I wanted to build a model of the ST/PT.
I found Richard Jarel's beautiful Ryan ST UM kit designed to use PZ UM electronics/mechanicals and ordered a couple but have yet to finish one. See link for build:http://www.rcgroups.com/forums/showthread.php?t=1322676

After having read more horror stories about Banana Hobby than Hobby King, I ordered from HK. Problem was, HK doesn't sell the Silver/Yellow version so I ordered the Blue/Yellow version and painted the blue bits silver. I also absolutely despised the mal-treatment of the rudder stripes by the mfr. and repainted with appropriate 13 stripes - 7 red, 6 white horizontal and 1 navy blue vertical...!!!!
I carved a pilot figure bust from pink foam and painted him up and assigned him to fly Ol' # 41.

Thanks to all you previous posters in this thread. You help novices like me to build a better model and increase the enjoyment of it!

Attached are some pics of my ongoing work in progress...
I hope you like them but would be happy to hear comments.
Cheers & Blessings!
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Old Jul 23, 2012, 10:45 PM
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United States, TN, Knox
Joined Sep 2011
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Ryan ST- Ole # 41

PS: Here's where I got the idea to use the #41 instead of something else:
from the San Diego Air & Space Museum Archives, a portrait of the designer/builder of the ST/PT series aircraft, T. Claude Ryan with a couple of the planes his company built ...
Cheers & Blessings!
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Old Aug 25, 2012, 05:24 AM
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Originally Posted by 4x4rc View Post
Not worth it I think, ground handling is bad enough as it is.

If you want to get CG forward (which I think you need to do) the best way to do it is to move the ESC into the nose section. That will move its weight forward, allow for better cooling, and at the same time allow you to move the battery to the very front inside the fuse. Here's one way to do it:



I repowered the bird with a RCtimer 2836/7 spinning a 9x6 or 10x4 prop but the same conversion can be done with the stock power system. On the underside of the nose I cut away some foam and epoxied the ESC onto the resulting pad. I drilled a tunnel through the foam from there at an upwards angle to end in the cavity for the wires inside the fuselage. This is easily done with a 10mm metal tube that I sharpened at one end. Push and turn it to cut the tunnel into the foam, much neater than drilling. The foam cowl received an air hole at the rear to let out the warm air around the ESC and still fits over everything to look stock.

With this setup and a 20C Turnigy 2200 3s battery CG will be right underneath the plastic wing struts which is good.
hi , i just received mine , the mod you did is quiet initutive ,may i ask how much kv of that motor is???????

i have plenty of 750 kv and 1400kv motors which one goes better????????
thanks
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Old Aug 25, 2012, 05:37 AM
Fly, crash, glue. Repeat.
Belgium, Walloon Region, Plombières
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It's an 1120 kV motor.

Which one of your motors is suitable depends on more than just the kV rating. First look at the power output and then determine which prop size you need to generate the thrust you want. A tool like Drive Calculator will help you do that.

You want something in the neighborhood of the AUW in thrust, so 850g+. The biggest prop you can fit is an 11" which might be ok for your 750 kV motor provided it can spin it. With the 1120 kV I measured 850g with a 9x6 and 1040g with a 10x4.

Good luck.
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Old Aug 25, 2012, 06:06 AM
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Originally Posted by 4x4rc View Post
It's an 1120 kV motor.

Which one of your motors is suitable depends on more than just the kV rating. First look at the power output and then determine which prop size you need to generate the thrust you want. A tool like Drive Calculator will help you do that.

You want something in the neighborhood of the AUW in thrust, so 850g+. The biggest prop you can fit is an 11" which might be ok for your 750 kV motor provided it can spin it. With the 1120 kV I measured 850g with a 9x6 and 1040g with a 10x4.

Good luck.
okay thanks ,one more question ,,did you cut the foam right behind the old motor mount?????
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Old Aug 25, 2012, 06:17 AM
Fly, crash, glue. Repeat.
Belgium, Walloon Region, Plombières
Joined Jul 2011
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Yup, right behind the slot the original motor mount sits in. Don't remove more than necessary because every mm counts in getting the weight forward as far as possible to maintain CG.
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Old Aug 25, 2012, 06:23 AM
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Originally Posted by 4x4rc View Post
Yup, right behind the slot the original motor mount sits in. Don't remove more than necessary because every mm counts in getting the weight forward as far as possible to maintain CG.
okay thanks ,im gonna get on to it now
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Old Sep 09, 2012, 07:38 PM
Getting good at foam repair
GTrain's Avatar
Australia, QLD, Surfers Paradise
Joined Aug 2012
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Hey guys the yellow / blue sceme is on liquidation sale at HK global warehouse for $59.95

https://www.hobbyking.com/hobbyking/...ellow_PNF.html

G
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Old Sep 23, 2012, 04:46 PM
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Southern Vermont
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Hi all, I was just given one of these that was too much for the original owner. Looks like he had a wing break (repaired w/epoxy) and a few small other dings, but all in all it's in very good shape. Looking forward to modding it a little and flying it. I'm used to flying an Artech spitfire of about the same size and a Tian Sheng Corsair also about 1000mm span. I also fly my own design scratch built foam Brown B-2 racer, a somewhat similar plane in shape and size.

First impression on this plane is that it is heavier than it needs to be, and tail heavy, as many of you have posted earlier in this thread. I will be moving the battery and ESC forward, as they are in the Brown Racer.

I would guess that the flying wires are really decelerating the plane fast at low speeds, and may be partly responsible for stalling -- along with weight and aft cg. I will be flying with a 1300 mah battery to keep weight down.

I also noticed a report of falling out of loops to the side. In my experience that is a direct result of too much elevator throw. I had the same problem in the spitfire, and only finally cured it by reducing throw after trying everything else. The Ryan has a huge elevator, and I bet that is a contributor. I expect that it won't take much throw to do a good loop.

Mine is a pretty ugly orange and blue. That might get changed down the road, but only if I can reduce weight first.

Looking forward to working out the kinks on this plane.
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Old Sep 23, 2012, 06:11 PM
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Looking at the wing, I think I'm seeing a bit of wash-in.

I might pull the rigging off and try to warp a little washout into it with a hair dryer....
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Old Sep 23, 2012, 07:37 PM
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Weighed mine. With my 1300mah 3S batt in it it weighs 27 ounces. Yikes! My Brown Racer, A little larger weighs 20. Where does that extra 7 ounces come from? The last owner did put a pilot and a big toggle switch in the cockpit. Those will be jettisoned.

I pulled the steel ballast weight out of the nose. Pulled the rigging off of the tail and upper wing so far. That stuff alone weighs about an ounce and a half.

I'm cutting a hole -- rectangular shaped, in the top of the fuselage, just forward of where the cowl seats (cowl is off) the battery will slip down vertically there. A vertical battery concentrates the most weight in one place -- it isn't spread out horizontally -- and it is now far more forward than it would have been if placed in the regular hatch.

Looking at the wheels, they are both too small for my grass field -- I'm sure -- and look quite heavy. I think I'll trade them for larger diameter foam wheels. There is plenty of room in those wheel pants for a bigger wheel. I bet the foam ones are lighter.

Rigging will come off of the bottom of the wing, too.

And the ESC will mount forward, as has been done before in this thread.

Prop also looks heavy -- probably no one worried about it, as it added weight forward which helped balance. But moving the battery forward might make it possible to go lighter.

I think I may go with a GWS EP9050 which might be lighter and bigger at the same time. The current prop measures 8-1/2" dia -- no idea of the original pitch but it looks high.

Noticed what looks like a lot of downthrust. Not sure if that has been increased by the crash this plane apparently had. But reading the thread about the diving tendency on hand launch, I think the downthrust is excessive, out of the box. Low wing planes generally don't need much downthrust, unlike high wing cabin jobs.
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Old Sep 23, 2012, 08:44 PM
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Quote:
Originally Posted by vtdiy View Post
Weighed mine. With my 1300mah 3S batt in it it weighs 27 ounces. Yikes! My Brown Racer, A little larger weighs 20. Where does that extra 7 ounces come from? The last owner did put a pilot and a big toggle switch in the cockpit. Those will be jettisoned.

I pulled the steel ballast weight out of the nose. Pulled the rigging off of the tail and upper wing so far. That stuff alone weighs about an ounce and a half.

I'm cutting a hole -- rectangular shaped, in the top of the fuselage, just forward of where the cowl seats (cowl is off) the battery will slip down vertically there. A vertical battery concentrates the most weight in one place -- it isn't spread out horizontally -- and it is now far more forward than it would have been if placed in the regular hatch.

Looking at the wheels, they are both too small for my grass field -- I'm sure -- and look quite heavy. I think I'll trade them for larger diameter foam wheels. There is plenty of room in those wheel pants for a bigger wheel. I bet the foam ones are lighter.

Rigging will come off of the bottom of the wing, too.

And the ESC will mount forward, as has been done before in this thread.

Prop also looks heavy -- probably no one worried about it, as it added weight forward which helped balance. But moving the battery forward might make it possible to go lighter.

I think I may go with a GWS EP9050 which might be lighter and bigger at the same time. The current prop measures 8-1/2" dia -- no idea of the original pitch but it looks high.

Noticed what looks like a lot of downthrust. Not sure if that has been increased by the crash this plane apparently had. But reading the thread about the diving tendency on hand launch, I think the downthrust is excessive, out of the box. Low wing planes generally don't need much downthrust, unlike high wing cabin jobs.
Following along to see your progress. Good friend of mine has a new one he picked up in Toledo last year and wants me to maiden it for him. Needless to say after going through this thread I'm a little reluctant.
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Old Sep 23, 2012, 09:02 PM
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Southern Vermont
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Well, mav913, also in this thread people have flown it without physical modifications. It's just that it is a little heavy mainly, has a fair amount of drag, and you have to watch the CG. So I wouldn't say it is something to be afraid of -- just realize its likely flight characteristics as an intermediate (or better) flyer.

I like to tune planes, and just reading the descriptions, I think I can make the plane a lot better than it was out of the box.

I've experienced a lot of the little problems mentioned in this thread at different times in different planes, and eventually figured out how to solve each -- usually the hard way. I have plenty of experience with repairs!

And since I'm mostly a scratch builder, I'm not afraid to cut a hole somewhere or change something. Foam can pretty much be endlessly repaired. At least thick foam can.

I'm not opposed to rigging either. But if I do add it back, it sure won't be made of hard wire, springs and screws like I found on this plane! Fishing line is a lot lighter, and has less air resistance than springs (and they were at both ends of all rigging!)

But I'm not overly concerned with rigging on this basically sport scale model anyway. I do like a good performing plane, and also one that flies at reasonably scale speed. And for that we need light weight. Much more than pseudo-scale details like protruding styrofoam rivets and steel wire rigging.
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Old Sep 23, 2012, 09:35 PM
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Here's the new battery location. I traced around the Lipo, and then started chopping away the foam with an x-acto knife.
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Old Sep 23, 2012, 09:42 PM
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I'm using a 1300Mah 3S Lipo btw. That is plenty for a plane of this size. I have read of others using 2100mah or larger batts in order to try to get the plane to balance.

But this just increases the plane's weight more than it already is. The Ryan really needs to go on a diet.

A larger heavier battery further back really doesn't alter the CG much. Because by increasing its size the battery gets longer. But if it is already up against a bulkhead, the way it gets longer is by extending aft, which is the opposite of what you want!

By simply moving the battery forward (several inches in this case) you alter the CG much more, while keeping the overall weight low. We can then ditch the ballast that used to be glued into the front of this plane.
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