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OS 55AX - Phoenix 7 Tank Height

Old 07-15-2014, 11:46 AM
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tomfiorentino
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Default OS 55AX - Phoenix 7 Tank Height

Hi guys,

I know we all know about the tank height issue in the Phoenix 7; I recently changed to the Dubro 16oz tank which fits in the ARF fuse like it was made for it, and the center of the tank is about 1/2 inch lower...that has helped mitigate issues all the way around.

I have the OS 55ax, red Jett muffler, 15% Omega fuel, 11X7 APC prop and I'm getting 13,440 rpm on the ground, no flights with this set-up yet. I ordered a few 12X8's at my LHS as I read that is a great prop combo with this engine and exhaust; I'm interested to see what that does too.

My question relates to the effects of the tank height (and fuel level) as it relates to idle and transition in addition to HS needle sensitivity. If you can, please confirm what you think is normal vs. something I should keep working at:

1. I'm finding 3 clicks to be the difference between screaming RPM and blubbering rich. This seems to be more sensitive than any OS I've had before so I can't be so sure if this is coming from the performance exhaust or not. Thoughts?

2. At less than half tank, idle gets better and transition gets even a little better yet. Does the lower tank volume have a mitigating effect on the tank height issue or is the muffler pressure alone enough to keep the whole system stable regardless of fuel level? I am hesitant to mess with the low speed needle because the issue with idle seems to change with fuel level (see #3), so I don't want to start chasing my tail.

3. Above half tank, it loads up on an extended idle and when I move to WOT it needs two very quick pinches of the fuel line to break open to 13,000+. I'm thinking it will unload in the air quicker...anyone take a guess on that?

I'm good enough to fly and will probably do that on Thursday. That should give me information about what is going on in the air, but in the meantime, who has some thoughts?

Thanks,
Tom
Old 07-15-2014, 01:36 PM
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TonyF
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I have helped Jamie Schoolcraft with one of these engines in his ARF Curare. We are running a 10cc Quiet pipe on it with an 11x9 APC. It turns about 11,700 with that prop and seems like a very nice set-up on that light model. It's not real fast but it has plenty of vertical. With that pipe the needle is not sensitive at all. So my guess is that the Jett muffler is causing your issue. I have seen that sort of problem with other similar mufflers.

As to your idle issues, it sounds like it's just a bit rich. Might run OK in the air but I would lean the idle a bit.
Old 07-16-2014, 01:50 AM
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tomfiorentino
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Thank you TonyF...the more I think about it you are probably right. Today is beautiful in upstate NY; leaving work early; going flying!

I'll creep in the idle screw a little at a time and lean it out while I'm at the field. I'll also get to see what it does in the air and report back to let you know how I made out with it. I'm very interested to see how fast it is too and as much fun as the 50cc stuff is, I'm looking forward to just throwing a .60 size plan in the car and going flying!

By the way, if this is the same TonyF that did the Phoenix7 ARF build, thanks for the tip on the Dubro tank! Fits perfect!

Tom
Old 07-16-2014, 05:41 AM
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flywilly
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Hi Tom,
First, the Jett muffler (or similar) is essentially a pre-tuned pipe and has an ideal rpm range. This set-up is 'tuned' by finding the prop that suits the ideal rpm range. Your description of a very sensitive high speed needle would be corrected by lengthening a tuned pipe set-up. In your case, you probably should try a smaller prop (11x6) which will turn more rpm and be a better 'fit' for the tuned muffler. I suspect the 12x8 will aggravate the needle sensitivity, but would work well with the stock muffler. The new 'AX' series OS engines seemed to be designed for optimum performance at lower rpm (less noise, too). The set-up Tony mentioned (55ax with 11x9 prop @ 11,700rpm) is probably better suited to that engine. I would guess similar performance with a 12x8. Great flying weather - enjoy!
-WIll
Old 07-16-2014, 06:44 AM
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Will is correct. Call Dub and tell him what rpm range you want and he will make you a muffler. I use the red Jett muffler a lot, but it is tuned for a much higher range than you are running. You will either need less prop load or a muffler tuned for lower rpm.

Good luck

Scott
Old 07-17-2014, 02:35 AM
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tomfiorentino
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More good advice...thanks guys.

I flew last night with the 11x6 and was getting 13,877 on the ground; couldn't get near the 14,500 I have been reading but that's ok. One of our members is a cop and he happened to stop by so he hit the Phoenix with his radar gun. We had 117mph straight and level and I had a ball! The plane flies great...

i did lean out the low end slightly and I think I have it pretty good right now. The engine runs great, idles great and has that great instant transition. The carb shuts things off pretty good, but I need to remember to keep my hemostat in my pocket to clamp the supply line when I shut it down. It just works better.

also I messed up my initial post by referencing a 12x8 prop. I meant to say, and in fact ordered, some 10x8 props because of what I have read here on RCU. I might fly again tonight and will try the 10x8 just for giggles.

all in all....it's a really nice combination.

thanks for taking the time to post guys. I appreciate it!

Tom
Old 07-20-2014, 08:19 AM
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Timthetoolman1
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Tom,

I've been running that combo for a couple years now with a 11x7 APC. You have to have a smaller pipe to make sure it keeps high enough RPMs to get on the pipe so you're good with the 11x6 too since it will have no problem transitioning.
I use PowerMaster 20/20 since I have 4 stokes too and it loves that stuff. I do run it rich though because it will burn through glow plugs. Dub will even tell you to run it almost to the too rich side and it will get on the pipe nicely, especially in the up lines where you need it.
I always run a Jett tank too so I don't have the problems with tank height or location.

Tim
Old 07-20-2014, 11:13 AM
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tomfiorentino
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Yea...5 or 6 more flights and I think its even running better. I need to do something with and exhaust deflector though, just to get the slop past the wing saddle.

At the end of the day while packing up I powered the receiver so I could retract the gear (its easier to transport that way). The mains went up and the nose wheel was hung up. I happened to touch the wire to the motor and the gear moved 1/4 of an inch. Jiggled it again and it moved another 1/2. Then the wire just came out; fell right out!

While I am thankful that didn't happen during flight while the gear was up...it still is a pita that I have to pull the nose gear and send it to Robart or Horizon to get it replaced. Darn it! And now I left for vacation so I wont even be able to return it until next week!

The plan is lots of fun though...great fun!

Thanks guys.

Tom
Old 07-21-2014, 07:06 AM
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TonyF
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What retracts are you using?
Old 07-22-2014, 09:36 AM
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tomfiorentino
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Robart electrics. Darn wire just fell right out of the actuator motor!
Old 07-23-2014, 08:00 AM
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TonyF
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That's sad to hear. Same thing can happen with other electric retracts. The vibration from glow is just too much. They are so easy to use it's tempting to try them. I've soft mounted the engine in my current P-7 so they might have a chance with that. But the mechanicals are working for me now.
Old 07-24-2014, 11:07 AM
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tomfiorentino
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I dont know Tony...I mean, they are made for 60 sized airplanes and the vibration from gassers isn't any better/less. Plus, we are talking 10 to 12 flights max!

But whatever...its not that big a deal.

Tom
Old 07-26-2014, 03:47 AM
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I posted on this before, a good while back. I used the old Kraft electric retracts back in the day with great reliability UNTIL I started putting them in glass fuse pattern ships w/ tuned pipes. I began having broken wires, or more often, the vibration ruined the electric motor. Often after only 10-15 flights. Must be something about the vibration frequency w/ higher revs combined with less wood in the area to help distribute/dissipate the vibration. The Kraft nose gear even came with it's own mounting box that was lined with foam tape. Used to carry a spare nose unit in the toolbox complete with wheel, etc. ready to swap out quickly between flights. Finally solved the problem on my original P7 back then by installing a Southern Pro nose gear. On my current H9 P7, I simply went with Southern Pro for the nose and mains. Have about 50 flights on the bird now with absolutely no gear problems.
Old 08-01-2014, 08:10 AM
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tomfiorentino
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The problem I am having is a direct function of today's internet-based sales "order" world which is awful. And despite my best efforts to buy and order absolutely anything I can to keep my LHS afloat, none of this works for me. Plus, it is another failed attempt to supplement my hobby interests with this ARF world because the demands of my professional/personal life require it at this point. In every instance it has seemed like it would be quicker/better/feasible/workable....but it hasn't been worth the hassle.

First problem...order electric retract tri-gear, can't get complete information from sales on phone, so take an "educated guess" that you are getting the correct item. First phone call.

Second problem was "order" shipped without the proprietary Robart extensions that are absolutely required for retract operation. Blackout...nobody knew this. I couldn't examine the part I was about to buy, the sales folks can't be that versed in every single product, but when you ask them to physically check the part for you, they can't because it is sitting in the warehouse somewhere and the only thing salespeople have in front of them is the same computer screen I'm looking at. Second phone call.

Third problem, was that the proprietary extensions are not sold by Horizon. Those come from Robart directly. Third phone call. And even though the tri-gear retracts are a "totally different unit" that are designed "only for the Phoenix ARF" they don't work for that ARF. You can't buy a Hangar 9 ARF and HAN500E special retracts for Hangar 9 ARF and put something together that works, because you have to buy extra parts from the manufacturer. Blackout...nobody knew this either. Another phone call...another order...another waiting game for shipping, postage etc.

Fourth problem, after a few flights...the nose gear wire broke/fell out. Fill out the "internet repair form", print it and include it with the shipment back to Horizon. Trip to post office, postage, waiting game etc.

Fifth problem, phone call to check status on repair of part that broke (you won't get through on technical assistance, repair line etc. the only thing to do is go through sales...THAT line they answer, funny). Naturally, sales doesn't know (I knowingly called the wrong line)...So I figure I'll beat the whole system, take it on the chin and just buy a new nose gear retract so I can fly before the snow comes.

Sixth problem, not gonna happen. Sorry. Horizon doesn't sell one nose gear Robart retract...they only sell the special HAN500E tri-gear as a unit, and the mains are still in my wing at home. Darn...then I'll buy a whole new tri-gear unit...thinking I'll just use the mains or whatever in another project.

Seventh problem, sorry, that ain't gonna happen either! They are out of stock. The tri-gear unit is out of stock so I couldn't buy it if I wanted to! Blackout...no idea when more will be in stock. Silence...what to do now...

Then I'll go back to my status of repair question...oops... Horizon doesn't repair Robart retracts. What?

So let me get all this straight. You don't repair them, you don't think you could break apart a tri-gear set to send me just the nose gear, and you don't have any in stock anyway...with no idea when, if ever, you will get any. Transfer the call to someone who might be able to help me...which apparently is the same line that I can never get through on directly. Sitting at my desk...screw it, and hang up.

Call Robart. $95 bucks for a nose gear replacement. And in the process of that discussion, I find out that Horizon is probably going to send my retract back to me with a note of some sort telling me to send it directly to Robart for repair.

There are other aspects to this that make it even worse but I'm tired. I'm feeling a little better to vent though...but good grief this whole thing is stupid. I just don't have room for these kind of time-consuming antics with such a short flying season and so little time to devote to this in general.

Sometimes the simplest things are so hard. I want my old world back so I can go in to the LHS and walk out with exactly what I needed because I looked at the part, handled it, test fit it etc. etc. Not to mention I got to meet a few people in the hobby and share some stories, experience and a good laugh. Nope. No more. Today it's more time consuming and more expensive, press 1, press 2, click click I have no idea...and 90% of the stuff is junk geared for the quick fix folks who have no long-term dedicated attachment and commitment to anything, much less RC.

To be clear I'm not trying to flame Horizon...really...they are in a lose/lose situation as well. It is too hard to support the details of this hobby and the millions and millions of proprietary products and combinations out there using this electronic world. Those guys are a victim of the same problem, and our paths just happened to cross today. That's all. Really. It's just frustrating.

Right now, I have a plane at home. I have a nose gear at Horizon, who is out of stock, who I got tired of waiting for so I hung up the phone. I'm not calling back either. Screw it. Another couple days of this and the servos/engine/exhaust are coming out and the ARF is going to the gravel pit where it will not withstand my Smith and Wesson E Series 45. No joke.

Tom
Old 08-01-2014, 03:30 PM
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Jim Oliver
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Simple solution to all the retract frustration----Spring Air!
Old 08-01-2014, 08:56 PM
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pitstop000
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I'm with Jim, SPRING AIR!

Last edited by pitstop000; 08-02-2014 at 01:43 AM.
Old 08-02-2014, 04:51 PM
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TonyF
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I've seen more gear up landings and gear down during the contest flight with air gear then anything else.
Old 08-04-2014, 08:00 AM
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I am also a Spring- Air guy, but with the current generation of current limiting, proportional retract servos, I am leaning toward mechanical retracts for my next installation.

Robert
Old 04-13-2015, 03:15 AM
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tomfiorentino
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Originally Posted by tomfiorentino View Post
I dont know Tony...I mean, they are made for 60 sized airplanes and the vibration from gassers isn't any better/less. Plus, we are talking 10 to 12 flights max!

But whatever...its not that big a deal.

Tom
Ugh!!! We finally got a break on the upstate NY weather yesterday...andI flew the phoenix 7; we even had some snow still on the sides of the runway.

Three beautiful flights and then the dreaded nose gear retract wouldn't come down so I did another wheels up landing on the belly. I'm getting really lucky; no damage again.

The problem is the nose gear wire breaking loose again. When I hit the retract switch and jiggle the wire I get intermittent operation. Robart just repaired this in the fall and its broke again in three flights!!

I know some of you have posted indicating this is a vibration issue but I'm using these retracts in a manner consistent with what they are desinged for! Its frustrating.

I'll call Robart today, but one thing I have noticed is there is no mechanical strain/retention relief where the wire comes out of the motor housing. The wire has a piece of heat shrink on it, but the motor housing forms a space all the way around the wire. I'm wondering if something can be done there. Also, the wire itself (and the proprietary extensions) is very, very stiff. It's so stiff it actually feels like solid wire instead of anything stranded. So, the combination of the stiff wire and the lack of mechanical restraint means that any movement at all is born by whatever solder joint they have inside the housing. I can't tell what is going on inside the motor housing.

Anyone taken one of these apart before? I'm contemplating taking it apart myself so I don't lose two weeks sending stuff back and forth.

Tom
Old 04-13-2015, 07:09 AM
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Jim Oliver
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Same answer as before--------Spring Air
Old 04-13-2015, 03:02 PM
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Spring Air's work every time. Never a failure with me.
Old 04-13-2015, 05:56 PM
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RCDENT
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(To be clear I'm not trying to flame Horizon...really...they are in a lose/lose situation as well. It is too hard to support the details of this hobby and the millions and millions of proprietary products and combinations out there using this electronic world. Those guys are a victim of the same problem, and our paths just happened to cross today. That's all. Really. It's just frustrating.

Right now, I have a plane at home. I have a nose gear at Horizon, who is out of stock, who I got tired of waiting for so I hung up the phone. I'm not calling back either. Screw it. Another couple days of this and the servos/engine/exhaust are coming out and the ARF is going to the gravel pit where it will not withstand my Smith and Wesson E Series 45. No joke.

Tom )

See my post just above yours. Get a servo and you can order a Dave Brown Southern Pro nose gear unit from Ohio Superstar. You can be making more flights while the electric retract guys are re-soldering wires. There must be something about the frequency of vibration as well as amplitude. My guess is the modern elecs would probably be fine in a balsa airplane, but not the nose of a glass pattern plane w/ tuned pipe. Learned that lesson the hard way decades ago. In any case good luck. The P7 is a nice bird and deserves to be enjoyed.


Dewey
Old 04-17-2015, 07:49 AM
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tomfiorentino
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Thanks for the post Dewey.

I had a nice conversation with Justin at Robart who I have to say was genuinely interested in the issue and was happy to listen to my thoughts about the design of how this wire moves into the actuator and what might be done to improve it. Thats really all one can hope for under the circumstances and he followed up nicely. I sent him a quick video of the broken part, and he took my thoughts to one of their engineers. Due today at my home actually, is a new actuator. From what he described they have made some sort of seal and support of the wire...hopefully that will fix it, although I would be lying to you if I told you I wasn't concerned about another wheels up belly landing. I've been too lucky with that maneuver!

I'll let you guys know how I make out. I'm this far already with the electrics that I will stick with them in the Phoenix for now. Not sure if I would use them again though...lets see how things work out!

Thanks again,

Tom

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