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How do you run up a Heli without it taking of ?


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solentlife
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Joined: 30 Dec 2010
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Location: Latvia / UK

PostPosted: Sun Jul 10, 2011 6:24 pm
PostPost subject: How do you run up a Heli without it taking of ?
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So here's my solution ... crude but effective.

Simply skids are tied down to a Workmate ... for larger Helis I would suggest a couple of heavy blocks fixed to the workmate !! But my 450 at full throttle and me WELL AWAY ... can rattle the workmate on the floor indicating it's about max size to use this ..

Anyway - I only use it to run up to test tracking .. and thats only half throttle is enough.

You will also note the use of a small battery .. in this case a 1000mAh spare I have left over from upgraded fixed wing ... saves using my actual flight batterys just before going out to flying site.





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Trouble
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Joined: 12 Aug 2010
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Location: Galveston, Texas

PostPosted: Sun Jul 10, 2011 10:07 pm
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Evil or Very Mad

Last edited by Trouble on Mon Aug 08, 2011 1:42 pm; edited 1 time in total
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tombo242
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Location: Santo Estêvão, East Algarve, Portugal. Now 82, but still feels 22.

PostPosted: Sun Jul 10, 2011 11:47 pm
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Great link there Trouble.

Solent life, shouldn't the blades be checked at hovering lift? Surely you don't hover at 1/2 throttle, got to be at least 2/3 to 3/4 for a proper check.

Tom.
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solentlife
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PostPosted: Thu Jul 14, 2011 2:15 am
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tombo242 wrote:
Great link there Trouble.

Solent life, shouldn't the blades be checked at hovering lift? Surely you don't hover at 1/2 throttle, got to be at least 2/3 to 3/4 for a proper check.

Tom.


I agree ... but having seen the effects of a blade throw ... and also the video of the guy who holds a heli down by hand to do tracking ... that video is also one that has been linked to by various forums for how to do it !! I want to play as safe as possible.
The mid or 50% throttle position on normal curve is 0 pitch. When tracking shows unequal blade disposition - that means one blade is higher pitched than other .... the datum point surely is irrelevant ? You wind in the high pitch blade to the zero pitch point ? or whatever.

I agree that because blade holders, rubber bushes etc give as rpm and lift comes on - you track in accordingly ... but major tracking error occurs because of mismatched links. At 50% throttle ... rotors run up to reasonable speed should show that ... well let's put it this way : mine certainly do. I track in at 50% throttle and in flight I see a good tracking set of blades ..........

If anyone thinks that I do not check tracking at lift / hover speed ... then think again ... I've been involved with helis RC since early 1980's ..... here's me checking tracking on my Irvine 20 IC powered job back then ...



In those days we were told to track in helis at speed just BEFORE lift point.
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platinum
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Joined: 31 May 2011
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Location: Bangkok Thailand

PostPosted: Thu Jul 14, 2011 6:27 am
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For the idia :
My old day tracking check of the real bird.

- On ground 100% rpm and collective up until feel lightly on the skid then check track of the blades.
- Shutdown and adjust.
-Test flight to check vertical vibration of the bird.
Anyway, it depend on the specific heli. Question

For my rc bird I fly then notice the track.

platinum
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solentlife
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PostPosted: Fri Jul 15, 2011 1:09 pm
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I thank moderators for calming down a situation on this thread but also wish to DISCUSS the issue ... it's no good brushing it aside as definite views are held by various. Healthy sensible debate can be beneficial here to help others particularly newcomers to the hobby. The issue as I see it is how safe is the act.

There are Youtube videos by 'quoted Experts' holding by HAND on a bench a 450 for tracking ........
There are other ways on Youtube including the lift of and observe.

My usual initial check is to have 450 on ground and run up rotors to reasonable speed but not lift .. adjust then to get best as near as possible .. run up again .. if very close to tracked - then a short run on the bench to get that final 'tweak'. The real check then being when flown.

The link by TROUBLE to another older forum ... Why we don't tie down etc. - having trundled through the whole thread leaves you in the middle ground wondering who's right.

It starts of with a Chinook being tied down in the FULL size world and it being purposely put into ground resonance to destroy the airframe. Many of the replies to the OP quote again and again that comparison of this and models is false.
There are others that claim whatever the resonance is - it's harmful and that is very true. But non-one proves that the theory applies to models. I agree that it's more than likely that damage can occur IF excess use / time while tied down. But in the original method as posted by me - we are talking less than a minute ... in fact more like 20 secs max just to see track of blades at just under lift point and actually not at resonance point anyway. I know my models resonance point - and I do not agree it is ground res. - it's as many on the other site say - based on heli itself straightening blades out .. getting into 'balance / equilibrium' ...

We also have a serious difference with full size - they can separate pitch and rpm but we have them coupled. They can as another says run up to 100% rpm without pitch applied. We cannot unless a very sophisticated model with separated functions ..
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silhouette015
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PostPosted: Fri Jul 15, 2011 2:48 pm
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solentlife wrote:
I thank moderators for calming down a situation on this thread but also wish to DISCUSS the issue ... it's no good brushing it aside as definite views are held by various. Healthy sensible debate can be beneficial here to help others particularly newcomers to the hobby. The issue as I see it is how safe is the act.


I have no object to that all, but let's keep it a "discussion" this time and not move it to the "personal attack" territory Wink

When I first started I got my first T-REX 450S set up by a LHS. The owner of the shop simply held the heli in his and and held it to eye level and revved up the throttle. Suffice to say that is not safe and highly not recommended! He's one of Thailand's champions so (I think) he knew what he was doing.

Anyways, I brought that up to point of that if a bare-hand can hold a T-REX 450 then strapping it down really well to a work table would definitely work as well. This is for a 450 class heli, anything bigger and I would say it's a no-no.

I wouldn't say holding it in your hand is safe either and highly non-recommended!
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solentlife
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PostPosted: Fri Jul 15, 2011 7:47 pm
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Thanks Silhouette .. I agree and hope that personal stuff can stay out this time. This forum has provided loads of help / info / advice for me to improve heli flying ... I was really upset to think about possibility of leaving .... it is THE best and makes the more well known Forums look what they are ... poor relations.

I don't know all the answers and no-one else does ... so we all debate and learn.

There is a widely acclaimed expert's Youtube vid where he tracks a 450 by holding down to bench by hand. That is in my view a suicidal act ... blades are within head area.

In old days we might at extreme hold a heli over head by both skids to run up rotors - the heli was then well above head, if a blade let go it would throw out and away from person holding heli .... if you think about it - this could be debated as a safer way than most others ......... depending on person holding heli of course

My way with the workmate does not transmit resonance as the skids are held by soft 2mm rope ... with a little give to allow the Heli to go through it's little shakes as blades etc. line up.

Anyway winds too strong today - so it's down to river at bottom of my garden and BBQ ... set-up music from my yacht to keep all happy and dancing
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nick_onelove
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PostPosted: Fri Jul 15, 2011 9:13 pm
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Hey I was just trying to calm people down, why was my reply and subscription deleted? Crying or Very sad LOL JK

I certainly don't mean to argue, but how exactly does spooling it up tied down protect you from blade throws better than just doing it in the air?
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solentlife
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PostPosted: Fri Jul 15, 2011 11:08 pm
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Tied down at least you know
a) blade will go of horizontal to release point
b) heli will not self-destruct throwing out other item
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platinum
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PostPosted: Fri Jul 15, 2011 11:20 pm
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Blade can throw out any time when spooling it up if the grip becomes loose.
Very dangerour especially the 450 and bigger.
My experienced, my fellow 450 threw out the blade and grip while hover.
Imagine how hard it hit the tree. Lucky nobody got hurt.

Check condition, security check....the heli and not close to it when speed up or if nescessary use min time as posible.

platinum
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nick_onelove
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PostPosted: Fri Jul 15, 2011 11:45 pm
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So it sounds like the moral of the story here might be to keep your grips and blades maintained and check them regularly?

If you're worried about a blade grip failing wouldn't tracking be the last thing on your mind?
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solentlife
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PostPosted: Sat Jul 16, 2011 12:43 am
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solentlife wrote:
Tied down at least you know
a) blade will go of horizontal to release point
b) heli will not self-destruct throwing out other item


My post has been edited by Moderators ... Why ?

Sorry but I want debate on this ... a very large post has been deleted and this has been substituted ... this is NOT my post.

Please put YOUR name to this post as it is not mine ............
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tombo242
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PostPosted: Sat Jul 16, 2011 9:46 pm
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I would love to debate on this as well, but it seems that what I know to be true just annoys others who know that what they know is true also. A real debate comes from considering the others and seeing how, or if, it could possibly be correct within your experience, not just dismissed out of hand.

Tom.
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