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Fast Lad Performance . Ace Hobby . Esprit Model

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Gasser Model RC Helicopters > Preddie again
 
 
pgkevet
Senior Heliman
Location: surrey UK

i have no embarrassment re my errors:
the tail blades measure 115mm blade length ..then a root.

I'm sure I've found the problem and suprising that newbie flew it as well as I did - the tail pitch control was binding on 'black crap' - dunno what - dried underneath it - so that it behaved like HH tail movement when it was in normal mode....suprising the servo didn't cook itself.

I flushed it all and freed it up and cleaned/flushed etc with silicon spray until the tail shaft is shiney as it should be. I can't remember but wonder if that output shaft had black anodising on it that has dissolved in something??

The only good news is that I must have been flying that tail pretty good by instinct (or fools luck) ...

pgk
06-26-2008 08:56 PM
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

Quote 
I can't remember but wonder if that output shaft had black anodising on it that has dissolved in something??

yep - more like black paint that goo's up - mine has worn off also. I regularly clean the tail shaft and put a few drops of triflow oil on there and the mainshaft on the washout and swash sliding area.

...yep...
06-26-2008 09:00 PM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
I meant to say that the grips survived a 2k hit into dirt, doubt slapping the air around will compromise the composite blade grips.

I suspect the feathering shaft is the weak link and that suffers the most damage but I would check the bores that the bearings fit into.

Ace
What could be more fun?
06-26-2008 10:04 PM
 
 
Eury
rrProfessor
Location: Ankeny, IA, USA.

In my case, i replaced everything. The grips, bearings, spindle and head block all went in the trash. Personally, I see plastic grips as consumables, if I have a bad crash, they get replaced. I've seen people not replace grips in the past and have it bite them when some unseen crack let go.


Nick Crego
I swear to God, I'll pistol whip the next guy that says Shenanigans
06-26-2008 10:18 PM
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

I agree replacing the grips after the crash is a good idea - my point is they didn't outright fail with stresses many magnitudes above the hardest that can be placed on these components during normal operations so the safety margin at 2k on composite main grips is probably way above a number of other components. - though I wouldn't mind having the $300 shiny head I certainly don't think it's needed for high headspeed.


lperagallo - have you seen or heard of an in flight head failure attributed to high headspeed?

...yep...
06-26-2008 10:19 PM
 
 
pgkevet
Senior Heliman
Location: surrey UK

..just to borrow my thread again:-)

..can we agree a target headspeed for a PUH231 stock for me..6.42 ratio. If shooting for 12500rpm that comes out around the 1950. .. which does seem unnecessarily high for me
1850 for an engine rpm around 12000 ?

Secondly

I reckon to use up my run-in 4 litres soon and move to Castrol TTS synthetic. Manufacturer recommendation is 50:1 for most applications (I found a Civil Aviation Authority sheet for use like that in microlights too). Is that reasonable or should I give it a gallon at 40:1 first?

pgk
06-26-2008 10:37 PM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

You will be fine at 1850, heck I run 1650 and it is happy.

Ace
What could be more fun?
06-26-2008 11:42 PM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
Is that reasonable or should I give it a gallon at 40:1 first?

If you are uncertain about what you are doing then don't go any thinner than 46:1, 3oz per gallon. Why toy with unknowns?

Ace
What could be more fun?
06-26-2008 11:45 PM
 
 
pgkevet
Senior Heliman
Location: surrey UK

Quote 
If you are uncertain about what you are doing then don't go any thinner than 46:1, 3oz per gallon. Why toy with unknowns?

Hmmm..somewhere I read that one should follow the oil manufacturers recommendations. When uncertain I ask. And I'm not entirely sure where this 46:1 idea comes from..and doubt that there's any real practical difference between that and 50:1.

What's your rationale for 46:1 (apsrt from owning a 3oz bottle)?

For me Litres are as easy as US or Imperial Gallons and any ratio is easy to mix..

pgk
06-26-2008 11:54 PM
 
 
Fixit
Key Veteran
Location: UK

I’m running a 20cc a 231 and a 26 all on 40:1 with TTS, more oil content more room for error the 26 is running 19000 head speed and the 20cc is at 20000 and they all seem more than happy.
06-27-2008 12:45 AM
HOMEPAGE  
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
(apsrt from owning a 3oz bottle)?

That's about it. 40:1 would be some fraction of an once. Using the same logic what's the difference between 40:1 and 46:1? Sooner or later there is a difference. 50:1 is sooner. You can run it but the thinner you make the oil content the better you should know your engine. Some will say 40:1 is the limit for the unexperienced.

You make the choice.

Ace
What could be more fun?
06-27-2008 01:33 AM
 
 
lperagallo
Senior Heliman
Location: Westfield, Indiana, USA

jschenck,

No, I haven't personally witnessed any head failures thank goodness. I believe that Vick from Vblades told me not to run his blades at greater then 2,000 Headspeed.

What started this was the comment about increasing headspeed to fix a tail holding problem. There is no reason that a novice flyer should be running a headspeed greater then 1,650. The helicopter is much more controllable and less twitchy with the slower headspeed and a whole heck of a lot safer should something go wrong.

Also when breaking in an engine you want to take it easy on it as heat is your enemy and a new engine generates more heat then a well broken in one.

Pgkevet,

Why risk your engine on a 50:1 oil ration when most experienced flyers here are running between 3 and 3.5 oz per gallon. The margin of safety may protect your engine so if you make a needle adjustment that leans out the engine you won't end up with a piece of molten steel. In a Gasser you are not trying to get the last ounce of power out of it like a Nitro. The extra oil will not affect performance that you could see or feel.

Feel free to do what you want it's your engine.

Lou


Lou

Bergen Intrepid EB, G-26, 720mm; Bergen Turbine, Wren MW54; Raptor 50V2, OS50-Hyper
06-27-2008 02:16 AM
 
 
pgkevet
Senior Heliman
Location: surrey UK

let's all take a deep breath..

I'm not trying to be some sort of clever bastard. I'm trying to understand this and get it right.

There has to be an optimum 'cruise' rpm for the engine and with any gearing therefore an optimum headspeed.

Similarly there has to be an optimum oil percentage - indeed there has to be an 'average' oil content across an 'average' tune state.

I asked the question because I wanted an answer.. not to demonstrate some superior ability to run on more or less oil than everyone else. And it so happens that the recommendation i found for the oil was 50:1. Indeed I suggested to run a gallon at 40:1 for 'safety'.

If the recommendation of folk with experience is 40:1 then fine.. I don't have a problem with that. I do have a problem with arbitrary guesses and numbers clawed out of thin air. I thought that the wgole point of synthetic oils was ability to lubricate so well that they almost interfer with running in and too much oil will leave residue.. whatever type of oil. What you want from the oil is lubrication with some additonal cooling effect and stablity at combustion temperatures?? And if my limited knowledge is true then superior oils will cling and spread better and stay stable .. such that a good oil needs less because less is degrading and being lost???

Back to the tail. Again no need to obsess. I did say and meant that i would rework the tail and gave the suggetsion of higher headspeed if necessary to help. Abd I found what I believe is the problem. Again there has to be an optimum that gives the tail servo the least work?... a compromise between slider movement and rotor pressure.

My nature is to worry at stuff until I understand it and get it right.

I really do appreciate the advice here but it's always nicer to have some provenance behind it.

Quote 
No, I haven't personally witnessed any head failures thank goodness. I believe that Vick from Vblades told me not to run his blades at greater then 2,000 Headspeed.

(Ipergello. please accept I only chose this statement for an example.. not knocking your advice or opinion)

That recommendation could be made for various reasons: speed/lift/drag on blades leads to functional limits at that speed, a speed at which the blade itself risks failure or torsional imbalance along its length. Or indeed a point at which centrifugal forces risk failure of grip or feathering shaft bolt threads (wouldn't kame a difference what the grips are made of)... yet an assumption that it's the blade grip.

It doesn't mean the recommendation is wrong. BUT it misleads

pgk
06-27-2008 07:46 AM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
Similarly there has to be an optimum oil percentage

But there are many many variables in that equation to achieve optimum. Through your own admission you have demonstrated a lack of expertise(jokingly in some cases).

Remember the choice is yours. When you become the next Bill M. you will be able to run the full 100:1 listed on some oils or even take bets on this forum running no oil at all!

Ace
What could be more fun?
06-27-2008 12:23 PM
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

pgk,, You are 100% correct in every one of your statements above,,

Quote 
There has to be an optimum 'cruise' rpm for the engine and with any gearing therefore an optimum headspeed.


Quote 
Similarly there has to be an optimum oil percentage - indeed there has to be an 'average' oil content across an 'average' tune state.



Quote 
. What you want from the oil is lubrication with some additonal cooling effect and stablity at combustion temperatures?? And if my limited knowledge is true then superior oils will cling and spread better and stay stable .. such that a good oil needs less because less is degrading and being lost???

This is one of the best statements I have read, You have a great understanding of how and why things work, What gets me is when people say, by running more oil, your safer, NOT TRUE!!! well maybe by seconds, but that's all,, if your running lean,,, Then no amount of oil is going to save your engine,, Period!!! You might get a extra few seconds, but that's it,, There really isn't allot of variables in that equation to achieve optimum. Just a few, and you stated them all in your post above,, Yes you want your engine is the sweet spot, and you get this by gear ratio's and knowing what your head speed is,,, yes use the oil as recommended, or more but not triple, as some post,, I ran 2oz.,, 64:1 for years, but the engine builder ask me to up that just a tad, to 2.5oz, 50:1, (Amsoil Saber),,, and set your needles as soon as possible, Get them close to start with,, You don't have to run a engine in really rich, you will get build up, just as you stated, You don't want to run lean, but that topic has been discussed here in length ( you know which topic to look at ) From what you have posted here, your going to do just fine,, XGM/VGM

John Crotts
www.soonerhelicamproductions.com
06-27-2008 01:47 PM
HOMEPAGE  
 
 
pgkevet
Senior Heliman
Location: surrey UK

I feel stupid and i'm paying for it

I flew today.. gusting to 25mph but Preddie was very stable. Nothing adventurous or outside my abilities.. just circuits and listening to the engine and climbouts. Towards the end of the second tank (5th 10min flight) I lost left aileron 100yds out and 100feet up..sudden left bank and nose in.. carnage. Someone else better might have done better..all I managed was to realise I had no control and hit throttle hold and shut off.

The reason is embarrassing. I had been using Preddie on the bench next to the Spectra build with an extenion lead from his rx to test the new servos. Because of that I'd loosened off the extra binding for one servo plug and forgotten to tie it down again at the end of the test session.. that servo plug vibrated loose on me.

Oh, the tail was holding well..so that's sorted.. or it will be with a new boom. The list is too long to even consider documenting.

I'll pull off the bits needed to finish the Spectra and then order up the parts..

When I told wifey how much my mornings entertainment had cost all she said was "It would have been cheaper to hire a prostitute and an eightball" - but I don't think that was said as permission

Quote 
your going to do just fine

..if I can stay in the air!
So what is best rpm for unmodified 231PUH? 1200??

I can practice by running in a spectra...

pgk
06-27-2008 02:24 PM
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

sorry about the pred going in again - gotta say, really like your attitude though! It's tough for me to accept a crash not due to LOFT (lack of f'n talent).

Wife sounds understanding

...yep...
06-27-2008 02:44 PM
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

Man...

So sorry to hear about the crash. Things like this are painful especially when they could have been avoided. I'm sure you'll be able to rebuild it, its just not fun to have to do so from a silly thing like this. I had to rebuild mine when some careless or nasty airplane pilot slammed into my heli from the bottom up, and every time I went down to the basement to work on it I was shaking my head as it was something I wasn't supposed to be doing.

As far as headspeed, there is NO REASON you should be running 1900 or 1850 or whatever, you're a BEGINNER! Forget about turning it up for max performance, slow it down, and concentrate on flying it and enjoying it. Only later, MUCH LATER (like maybe 75 flights later), turn it up when you're comfortable to see what it can do. Your first flights with a gasser should be orientation flights where you get to know the machine (like in a new job), not screaming max possible headspeed and trying to fly it by the seat of your pants.

As far as oil, put some more in there, it won't hurt you. Put less in there, and you open the door to hurt you. John believes no amount of oil will save you but I disagree and know that you'll have more room for error or forgiveness with the needles the more oil you have. Anyway, I'm not going to make a big subject on this, as Ace says, if you're Bill you can run the heli with NO oil, so the range is quite large and the motor is yours to keep - noone here is going to warranty it for you if you burn it up.

Be careful with wires on the Spectra-g -- the frame edges are quite sharp so make sure they don't rub on the edges and get cut. Either cover the edges, reroute the wires or protect the wires.

-=>Raja.

1005 Xcell Gas, BHH G26 3D Plus, Jewel Generator
Spectra-g, BHH G26 3D Plus, Jewel Generator
06-27-2008 02:52 PM
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

Dang pgk,, or (Lucky) which is your new name,,, Well a little preflight manitance might have caught that, but I know hine sight is 20/20,, Without some stress, I wonder how it came unpluged?? unless the plug was wore out or easy to plug in and out,, It should have stayed pluged in, unless something was pulling on it??? Yiekkkkkkkksssss this sucks, for sure,, Hopefully the Spectra will hold together better for you?? Well get those parts ordered, and have a beer, or a shot, of ta'kill'ya, and everything will be ok,, and stuff a 100.00 bill in your wifes panties,, that might make things better at home.. (for both of you) XGM/VGM

Quote 
So what is best rpm for unmodified 231PUH? 1200??

Yes I would say that 12,000 rpm on the stock engine will be in the zone, but you can try differant setting to see which one works best,,,

John Crotts
www.soonerhelicamproductions.com
06-27-2008 02:53 PM
HOMEPAGE  
 
 
pgkevet
Senior Heliman
Location: surrey UK

Quote 
Well a little preflight manitance might have caught that, but I know hine sight is 20/20,, Without some stress, I wonder how it came unpluged??

I haven't got an explanation. I'd plugged it back in.. just hadnlt tied it down. I've got all the plugs clipped together so they'll hold together but had loosened that from the bundle when playing with the spectra..sure had plugged it back in.. but assume just not well enough..it was the only one out on the ground and it fits with the way it went in.

I do always check servos via the tx before takeoff.. but this came loose 8 mins into the flight.. I doubt pulling the canopy off and a visual would have likely spotted it - if in well enough to be working.

You lives, ya learns, ya pays.

For a change all the parts are avilable UK and some out of stock your side.. but the price here is silly.. so I'll import what I can and wait. That was my reason for two gassers.. parts postage delays..

..so long as i can avoid cracking them both up the same week <rushes off to find wood to touch>

..my handle elsewhere is 'crash your way to success'

..just a shame they don't discount gasser parts in three-packs align-style..

pgk
06-27-2008 03:18 PM
 
 
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Thunder Power RC . Real Raptors . Mikado Modellhubschrauber

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Gasser Model RC Helicopters > Preddie again
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