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HelicopterGasser Model RC HelicoptersOther › Spectra Maiden flight NO-GO!
12-27-2008 02:05 AM  8 years agoPost 1
TERollins

rrApprentice

Culpeper, Va

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Well today I attempted my first maiden hover with my Spectra. Before I get into all the details of today, yesterday I fired the TRM231 up for the first time since I've owned the used Spectra. Ran a half tank of Colman fuel mixed 28:1 (4.5oz) with Honda (HRC) synthetic 2 cycle oil.

Today.....Started the heli in a couple of pulls. I let it idel for a few minutes to warm-up. Started my initial spool up and the tail violently spone around. Checked my 401 gyro settings and all seemed okay as far as the direction set on the gyro and my DX7 radio settings. Heli seemed to be rev'ing pretty high for a gasser. My throttle cure is set to 0-20-22.5-27-100 and I can't remember right off hand what I have my pitch curves set at. (Maybe 0-45-65-75-100) Tried to spool it up again and same thing, heli violently spone around. Didn't have a good feeling on what was going on. Took the heli back to the truck and pulled off the canopy. Looked at the main gear and the inner crown gear for the constant tail drive had a few teeth stripped off and plastic shavings were all over the place. What would have made the inner constant tail drive tail crown gear to strip? So now I need to order a new inner constant tail drive gear (MA0866-5) and figure out why the inner gear failed. A few other things on setup I have questions about. Throttle and pitch curves? What do I need to have these setup at in my radio for just basic hovering/forward flight? I did check and at mid-stick on collective I have zero pitch and all my servo's are at 90 deg. and everything seems to be mechanically setup correctly. I want to get the radio/pitch/throttle setup so that I can hover at around mid-stick. So here's my list of "to-do's"
1. Replace inner crown constant tail driver gear and figure out why it failed.
2. Re-check setup of throttle/pitch curves. (What should I have these setup in my DX7 radio and what should the pitch be using a pitch gauge at low-mid-high stick position.)
3. Re-visit throttle servo setup and adjust so heli can be shut-down using trim.
4. Review setup of 401 gyro and DX7 radio setup for gyro.
5. Re-check engine H/L needel settings.

Anything else I might be missing? Also does anyone know of a cheaper set of main blades that I can use on the Spectra? I currently have a set of SAB 710 carbon fiber mains but really don't want to use these just yet incase I have a little mishap. Thanks and I really appreciate the help!

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12-27-2008 02:45 AM  8 years agoPost 2
smallplanes

rrElite Veteran

S.C. ,SSA

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Well so far i've not flown a gasser(but i'm building one now) but it is possible the auto bearing could be letting go,that or maybe gear mesh was off a little. Like i said i don't know gas but it would be something to check. Hope you get it worked out.

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12-27-2008 04:59 AM  8 years agoPost 3
rbort

rrProfessor

Franklin, MA - USA

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Hmmm

Could be many things that would cause it. Gyro set incorrectly, tail gear mesh too loose, bevel gear not centered over the crown gear teeth, etc.

Don't know how you built it, etc. but I've seen different issues like that with people I've helped over the years.

#1 Check the gear mesh first. If you put in the gear in the right place and hold it steady not moving there should be little backlash back and forth as you rotate the head.

#2 check the gyro settings. Right rudder should PULL the pushrod towards the mainshaft. Pickup heli by mainshaft and rotate tailboom around to the right nose to the left, the gyro should pull the pushrod to the mainshaft (right rudder input). If incorrect it would explain why the tail spun around as you spooled up.

If not possible tail was not being driven is why it spun around. Goes back to #1 and the rest of the components in the tail. Set screws tight, tailboom pushed in all the way to the stop in the plastic boom guides, stop is those to the front not to the rear, etc.

P.S. It should have nothing to do with the auto hub. That is just to freewheel the mainshaft when the engine is not driving the transmission.

-=>Raja.

MA 1005 Hanson 280, 4136 flts
Spectra 27 3DMax, 3200 flts
Whiplash V1 Hanson 300, 1430 flts
Whiplash V2 Hanson 300, 196 flts

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12-27-2008 05:23 AM  8 years agoPost 4
TERollins

rrApprentice

Culpeper, Va

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Raja....I'm the third owner of this Spectra. First owner built and flew it about 3-6 times. Second owner only flew it 3 times. I initially checked everything over when I received the heli. The gear mesh looked okay to me. I think that the servo direction for the gyro was wrong and then between the heli spinning violently and me trying to maintain it caused the inner crown gear to strip a few gears. Once I replace the inner crown constant tail drive gear I'll double check the gear mesh and the other items you suggested. Any suggestions on some basic throttle/pitch curves for just hovering and some forward flight? Thanks!

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12-27-2008 06:00 AM  8 years agoPost 5
rbort

rrProfessor

Franklin, MA - USA

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Curves

Set the pitch curves to be linear: 0, inh, 50, inh, 100 for all modes.
Mechanically, it should be 0 degrees at mid stick, +/- 11 degrees at the extremes, and about +/- 5.5 degrees at 3/4 / 1/4 stick.

Set throttle curves approximately as follows:

N: 0, 18, 22, 25, 27, 100
IDl: 100, 30, 27, 30, 100
ID2: 100, 32, 29, 32, 100

Those are close to what I have now. I run a gv-1 with speeds of 1540, 1660, and 1780 in N through ID2 modes.

Your throttle linkage setup and mixture will change what the numbers are for your flight modes. Once you have everything set the way you want it, you can use the gv-1 as a cue to set curves so no change in rpms when you turn the gv-1 off and back on.

-=>Raja.

MA 1005 Hanson 280, 4136 flts
Spectra 27 3DMax, 3200 flts
Whiplash V1 Hanson 300, 1430 flts
Whiplash V2 Hanson 300, 196 flts

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12-27-2008 09:44 AM  8 years agoPost 6
TERollins

rrApprentice

Culpeper, Va

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Raja....I'm following what your saying but there is one thing I'm not 100% clear on. At mid stick I do have 0 degrees of pitch. At 3/4 stick are you saying that I should have +/-5.5 degrees of pitch? What at 1/4 stick? Not sure I'm following what your saying 3/4 / 1/4 stick.
about +/- 5.5 degrees at 3/4 / 1/4 stick

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12-27-2008 12:53 PM  8 years agoPost 7
zorba

rrApprentice

Montreal, Quebec,​Canada

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Raja same thing here.
Having the X9303 which has 7 point curve how do you do that?
On the DX7 was ok.
Saw me how to do it on the 9303 please. Pitch curve also.
I've set it up according to Malorie's setup.
Cheers

3-450's,rex500ESP,rex600G,Rex700G,Raptor60G,FreyaCW-EXII, VarioEC155, Logo20, Cessna310,CL-415,

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12-27-2008 01:56 PM  8 years agoPost 8
smallplanes

rrElite Veteran

S.C. ,SSA

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It might not be the auto hub but i have crashed due to the failure of this bearing in flight. It did not strip my gear,the head speed just went out of control and i had no powered lift and i had no choice but to try and auto it in a plowed up field,,it broke the gorilla landing gear and that was it. So i might just be what raja is saying,i just tought i would give you a heads up on this. It does sound like the gyro or servo was reversed

Thanks and hope you get it flying

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12-27-2008 03:44 PM  8 years agoPost 9
rbort

rrProfessor

Franklin, MA - USA

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Curves

Just make it linear. If you have a 7 point curve, set the ends at +/- 11 degrees and the middle to 0 degrees and let the other points default to a straight line linear curve. That's all I meant. 3/4 stick and 1/4 stick (throttle setting) will end up 1/2 way between 0 and 11 degrees which is 5.5 degrees.

Smallplanes, I'm not sure I follow how the auto hub crashed your heli. If it goes bad it just locks up meaning when the engine fails it will drive the outer main gear and clutch as well during an auto or a dead stick. With a running engine it will just operate the same way and drive the transmission.

I have never seen it fail where it doesn't drive anything and the engine just runs free. You're saying the head speed went out of control, like was overspeeding? How does that make sense that the auto hub failed? It sounds more likely that your throttle servo failed and went to the extreme full throttle and got stuck there. That would make more sense to me.

Please give more details on what you think happened, I'm interested to hear about it.

-=>Raja.

MA 1005 Hanson 280, 4136 flts
Spectra 27 3DMax, 3200 flts
Whiplash V1 Hanson 300, 1430 flts
Whiplash V2 Hanson 300, 196 flts

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12-27-2008 05:53 PM  8 years agoPost 10
smallplanes

rrElite Veteran

S.C. ,SSA

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No the servo was fine,i went back in my shop put another bearing in and it worked great,,the guy i sold it to is still flying it like that(same servo). Yes it was reving up and down and i had no power on the head,so the heli started a free fall i killed most of my headspeed on the way down so i pulled full negetive about -10 and was able to land farly slow. Like i've said before if it can happen it will happen to me. This was in a raptor 50 the new bearing was out of a stinger 50.

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12-28-2008 04:50 PM  8 years agoPost 11
arrio

rrApprentice

Newport News, VA

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Smallplanes, I'm not sure I follow how the auto hub crashed your heli. If it goes bad it just locks up meaning when the engine fails it will drive the outer main gear and clutch as well during an auto or a dead stick. With a running engine it will just operate the same way and drive the transmission.
I have not seen it with the gasser, but I have experienced auto clutch failure/overrun. The first stage of oneway failure is locking up. The second stage is rolling over center and not driving anything except the tail in a non-constant drive tail. Not sure how it would effect the tail on the Spectra. Drive it, or freewheel with the main shaft..

"fly it like you hate it"
Alfred (arrio) Riopel "more toys than time"

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12-29-2008 01:05 AM  8 years agoPost 12
bosshoss

rrVeteran

Chicago, IL

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All the thrott curve numbers are relative to your own setup.

Best to have a Optical tach and a friend calling out RPM on th efirst spin ups.....so you can get that Thrott curve right.

I had to flatten mine out so far, I was in disbelief.

Keep in mind , the last 1/3 or so of the butterly opening up does very little, in terms of non loaded rpm. You will be surprised when you get the hover thrott setting set, or near set.

When you look at the opening you wont believe how very little it is open.

Why Hover a Yak, when a Heli does it better?

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01-12-2009 03:28 AM  8 years agoPost 13
B.F

rrNovice

Graham, WA.

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Spectra tail problem is vibration

I have experience with the spectra gasser. What I can tell you about the gyro proplems is VIRBRATION. If you can find a way to isolate the gyro against the gasser vibrations you will be on your way. Sold mine because I was tired of screwing around with it. Went back to nitro.

B.F

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01-12-2009 03:42 AM  8 years agoPost 14
TERollins

rrApprentice

Culpeper, Va

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B.F....got everything sorted out. See my new thread:

http://www.runryder.com/helicopter/t486458p1/

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