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Century Hawk - Falcon - Raven - Predator > Raven bogs inverted

QuantumPSI
Elite Veteran
Location: Boston, MA

Quote
I always thought that the 50 standard ratio is the 8.5:1 (The Raptor 50 runs a 8.5:1 ratio), so I think that is probably the issue.

Mmm, that doesn't make it the standard. I have a Raven with the speed up gear with the 8.73 gear ratio and a 600N with the 8.5 gear ratio. Although the 600N has a little bit more pop, the Raven definitely powers through maneuvers a little bit more. Matter of preference to be honest. Would be nice if we could change gear ratios on all our helis but oh well.

I'm really perplexed by this one. Can the mainshaft move up and down in the frame at all? That could add or subtract pitch. I'd say for the time being bump up the throttle curve to a more aggressive setting. I wanna know if the engine is having a problem catching up to the blades. With the aggressive throttle curve and high headspeed you'll be able to tell if the engine is truly bogging. The rpms should drop to a certain level when climbing out hard but it should stabilize, this is when the engine falls into its max power band. If the RPMs continuously drop, there's a problem.

Also, can you give more details on your setup? What servos are you running? What blades are you running? Can you post pictures?

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

07-24-2008 06:55 PM

mikefoy6
Senior Heliman
Location: Thief River Falls, MN

I have the old gear (black not gray) in my raven 50 and it climbs out great, inverted or right side up.

I do have uni-flow on mine though...

There are 10 types of people in the world: those who know binary, and those who don't

07-24-2008 07:01 PM

Cambo
Senior Heliman
Location: Phoenix, Arizona

So here is the setup currently

Hyper/hatori SAB 5
servos s3050
Speed: .20 sec/60° @ 4.8V, .16 sec/60° @ 6V
Torque: 72 oz-in at 4.8V, 90 oz-in at 6V
These arne't the best but they will go 13 degrees of pitch without a problem. They are slower but i can live with that. I moded the realflight heli to have slower servos so i have been practicing on the same specs

coolpower 20%
Hurricane 600mm fiberglass i think is what they are called. Regardless they are stock

401/9254

throttle controled by JR 810 so it is faster than the s3050

the main shaft is tight on the fram

How high is too high on this thing

I started today at 100-65-45-65-100 and ended with 100-80-55-80-100. I am not sure if i should go more as i am worried about over speeding the head. I guese i could try something like 100-90-70-90-100.

07-24-2008 07:05 PM

Cambo
Senior Heliman
Location: Phoenix, Arizona

You know, i think my Raven already has the grey speed up gear? I didn't know the stock one is suposed to be black. The one that came in my kit was grey.

EDIT:

Bad news, i just checked and low and behold i already have the stuping speed up gear. I carefully counted the teeth and it came out to 53. HRRRRRRRR.

I am running out of ideas here and am thinking of buying a new engine. Possible the ys50 or tt53.

Maybe i broke the thing in wrong or did something worng when i first had it. Regardless, i wasn't capable of inverted flight then so i can't compare.

07-24-2008 07:11 PM

QuantumPSI
Elite Veteran
Location: Boston, MA

Do you have a header tank? I wonder if you're getting good fuel flow when you're inverted...

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

07-24-2008 08:56 PM

Cambo
Senior Heliman
Location: Phoenix, Arizona

Ya i have a header tank but am just not sure if it is helping. That is why i am concidering the YS

07-24-2008 09:06 PM

QuantumPSI
Elite Veteran
Location: Boston, MA

I dunno man, I wish I could physically see your helicopter but you're in Arizona. Do you have any other experienced people around? The climb upright is ok right? Try changing the spark? Make sure the engine head is tight?

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

07-24-2008 09:17 PM

jschenck
Elite Veteran
Location: La Vista, NE.

Something I haven't seen in this thread - does it climb well when the heli is upright?

Have you tried bypassing the header tank?

...yep...

07-24-2008 09:17 PM

QuantumPSI
Elite Veteran
Location: Boston, MA

Yeah, I thought the same thing Jschenck. It's implied by the topic but was never said explicitly...

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

07-24-2008 09:21 PM

TulOkFly
Senior Heliman
Location: Tulsa. OK - USA

Quote
that doesn't make it the standard

True, I guess I meant a ratio of around 8.5:1 is more common for 50s than 9.2:1 I think. Something to do with the torque of the 50 motors.
It has been a while since I had a 50 so I am probably not much help.

One thing I do remember is that I would set the max pitch for no bogging, no matter if it was less than 10 on the pitch guage. Response is mainly from keeping a good headspeed and not just from a lot of pitch, in my experience.

Keep dialing back the pitch and test flying and see if it helps. Cheaper to experiment that way than buy a new motor right away. IMO

Also, If fuel flow is the problem the motor would be going lean even in an inverted hover. If it runs about the same hovering both ways then it must be in the setup.

I have had helis that had enough play/slop that even though the pitch guage said 10 degrees if I grabbed the blades and put pressure on them as if air was pushing on them they were going to more pitch than that. So on the guage they had to be set with what looked like only 8 degrees, but no bogging and good response.
Good Luck!

Just Fly!!!
TRex 450
Blade 400
MX450XS (parts machine now)

07-24-2008 09:23 PM

mikefoy6
Senior Heliman
Location: Thief River Falls, MN

My hyper with a MP5 pulls +/-12 degrees just fine.

Couldn't hurt to try a uniflow set up. It takes about 5 minutes to do.

Basically just add a clunk to the exhaust presasure line, and add a vent. Your raven fuel stopper already has the holes molded into it for uniflow.

Read up:
http://runryder.com/helicopter/t271298p1

There are 10 types of people in the world: those who know binary, and those who don't

07-24-2008 09:32 PM

Cambo
Senior Heliman
Location: Phoenix, Arizona

Upright climbout is acceptable but not the best i have seen. I am not sure if fast servos would give me what apears like fast climbout because it is accelerating faster? The main problem here is going from upright to inverted. Anytime the heli is in the inverted orientation i loose HS. The engine doesn't sound like it leans out. It almost sounds like it gets really rich. The problem is i can't move back and forth quickly between inverted and upright because the HS drops.

I think, for the next, i will try a uniflow and bypass the header. I am scared of running the tank without a header but in don't see why not at this point.

07-24-2008 10:01 PM

QuantumPSI
Elite Veteran
Location: Boston, MA

I wonder if it's your muffler. I've never even heard of the SAB 5, but it's hatori so I'd expect it to perform well?!

I really wish I was in person to futz with it...

I like a challenge.

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

07-24-2008 10:04 PM

bcm
Senior Heliman
Location: Tuolumne,CA

here's my "opinion" from my experience. I use to have exactly the same response from my ravens, they get quieter and definately richer while inverted. I also believe that the cooling fan is not as efficient as some others, that being said I have spent this year leaning the needles on my hypers a couple of clicks at a time. It has made all the difference in the world. The back-plate is warmer than I was comfortable with at first, but, they are not too lean. The transition both up in rpms and down is smooth, and they're not "hanging on the pipe".
I am almost positive that youre mixture is a little richer than you think. I am hesitant to tell very many people to go leaner, because they're usually on the verge of "kill" as it is, but if you slowly lean( a couple of clicks max) at a time, I'm pretty confident you'll find the sweet spot. By the way I,ve got about 5 gallons of 30% thru the engines I'm referring to, and they're running very well. I can now do tick-tocks till my thumbs are numb.

07-24-2008 10:36 PM

HOMEPAGE

Cambo
Senior Heliman
Location: Phoenix, Arizona

I have wondered if i can go leaner. How can you tell if you have gone to far?

The muffler on the box says SAB5-RS
Strangley, heliproz no longer sells it and there is barely any info of it on the net.

HMMMMM

07-24-2008 10:44 PM

RICH.L
Key Veteran
Location: east springfield p.a.

Just wondering if the dx-7 has slider's on the radio like a futaba?

I forgot to disable mine on my 9c and it would alter my pitch and made it feel like it had no power!

another thing is how many gallons on the hyper,they are noted for rear bearings going bad and that will cause them to bog out and run like crap!!

I had two hyper 50's do the same thing,had them tuned up good but just would not get out of their own way,I replaced the bearings and put a new ring in and they would run super again.

also i had hitec digital servo's on my raven 50 and they had a transit speed of .18 at 69oz/inch of torque and they were plenty fast enough!!

Just some more things to consider.

rich

07-25-2008 02:00 AM

Cambo
Senior Heliman
Location: Phoenix, Arizona

Hi rich, funny you should mention that as i literally just replaced the bearings 6 tanks ago. I have aproximatley 7 gallons through it. The DX-7 doesn't have sliders thank goodness. My hitec optic 6 did and it drove me nuts.

There are a few more things i have done. First, i bypassed the header tank and set it up for a uniflow system. Really quick and easy, worth a try. Also, my pressure nipple long stripped out. To get the whole tight again I used JB weld and rethreaded it. It is holding strong but just in case i put a little bit of silicon in the threads to prevent any minute air leak.

I am going to see were that gets me and post back the results

07-25-2008 04:05 AM

helimatt
Elite Veteran
Location: Lafayette, IN

From what I've read thus far, sounds like the motor is too restricted- go with a different pipe. The motor may be a tad richer inverted by your current fuel system (Uniflow might help it), so less power.

Try an Align pipe, or MP5, or Hatori (which is the current one for the Hyper?), see what a difference it might make.

Also what fuel/plug are you running?

Never, ever, ever, ever give up.

07-25-2008 04:41 AM

jschenck
Elite Veteran
Location: La Vista, NE.

Is it possible some JB got in the muffler tap? No pressure in the tank would cause problems!

...yep...

07-25-2008 05:30 AM

Cambo
Senior Heliman
Location: Phoenix, Arizona

No, i made sure of that. I really might come down to trying a new pipe if it still flies poorly this weekend

Edit: i ordered a new MP5 from readyheli. I am, to be quiet honest, kind of anoyed with this hatori pipe. First off, the muffler bolts came loose no matter how tight i got them and eventually got to the point were when i came to land they were stripped. I couldn't get JB weld to hold the threads so i had to drill the holes out and put nuts on the other side. The pressure nipple stripped and and caused porblems. The thing is, i really haven't noticed amazing power from either of the two birds i had this in. I am wondering if maybe the pipe is to restrictive maybe causing backpressure problems.

07-25-2008 05:58 AM

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