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HelicopterAerial Photography and Video › Thinking of investing in a new ship ...
03-18-2009 05:17 PM  8 years agoPost 81
theslayer

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Munich-Germany

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Hmm, TT or MAH Blades is a bit what they look like... Perhaps SAB?

Daniel

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03-18-2009 11:38 PM  8 years agoPost 82
Hogster

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Excellent news

I found a pair of nice flat-head M5 screws at home which, when fitted, allow the blades to sit in place with no filing whatsoever! These are the screws (top is the stock bolt, bottom is the type of screw I've found):

They seem to be extremely sturdy to me and I can't see why they wouldn't be up to the task of replacing the stock feathering spindle bolts? Yes they're a bit shorter but that shouldn't matter too much?

At least I won't have to touch the blades now

Your thoughts are most welcome!

Cheers,

David

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03-19-2009 12:17 AM  8 years agoPost 83
tabbytabb

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seattle

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David,

Socket head cap screws are by far the strongest type of screw. That is why they are so widely used on RC helicopters. I personally would not fly the ship with the screw you have shown, especially in a high stress place like the spindle bolt.

Just my 2 cents, but this is one of those times when not spending 100 bucks for some new blades could cost you a couple grand. It is ugly when a heli throws a blade.

Tabb

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03-19-2009 12:22 AM  8 years agoPost 84
46Taylorcraft

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AZ

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I'd personally not trust those flat head screws.

FWIW I've flown TT 710's with the roots trimmed 3-4mm for years with never an issue.

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03-19-2009 01:05 AM  8 years agoPost 85
HugeOne

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Quebec, Canada

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Your thoughts are most welcome!
NO

Use only carbon steel screw, check RTL fastenenr...

Raptor e620 w/V-bar, Tango 45-06, Phoenix 85HV, TrueRC 12S1P 4000mAh

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03-19-2009 02:20 AM  8 years agoPost 86
Oyley

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feathering spindle bolts

David...I think you will find that the manufacturers in the main....supply high tensile bolts for this purpose and almost certainly on 600 size helis,for a very good reason along with the correct length.
Have you seen how far a blade flies when one lets go?

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03-19-2009 10:52 AM  8 years agoPost 87
Hogster

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Hi guys, thanks for the replies

Seems to be a unanimous 'don't do it'! Glad I posted here before going ahead

So I'm basically restricted to using the head as it is now ... so I'm looking for some new blades then! How about SAB 710mm wide chord ones?

http://www.modelhelicopters.co.uk/a...Blades_Sab.html

Can you see what the difference is between SAB224 and 226? Seems you pay £3 more for a difference in the name of the blade, but not the specs!

If I go with those I will phone the retailer and ask them to measure the distance from the blade hole to the root so I don't end up in the same situation as I am now ...!

With the pinion I've bought (12t) and the motor I'll be using (Actor 24-4) I'm looking at a headspeed of 1650rpm at 37V ...... how does that sound? Sounds a bit fast? That's the smallest pinion I can get for the 153t main gear though

Many thanks

David

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03-19-2009 11:09 AM  8 years agoPost 88
Hogster

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Alternatively I could go for a set of these:

http://www.fast-lad.co.uk/store/pro...roducts_id=4362

Which Tabb raved about here:

http://runryder.com/helicopter/t446521p1/

(well, not about the 710's directly, but Rotortech's in general)

Cheers

David

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03-19-2009 09:35 PM  8 years agoPost 89
CRCR

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Aus

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David,

How much interference is there between the blade and cap screw?

Most new Cap screws have a high Strength Designation of up to 12.9 so it should be fine to just cut a bit off the head of the cap screw.

Just make sure the you cut it by hand and don't let it get to hot.

A lot cheaper option than getting new blades.

You can get hex head bolts with a Strength Designation of 10.9, slightly less than the cap screw but still very strong, but the only problem with these is that there probably won't be enough room to get a socket in to tighten it up.

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03-20-2009 01:19 AM  8 years agoPost 90
Hogster

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When I got home today I had a closer inspection of just how much of the blade root was interfering with the spindle bolt ... as it turned out, not as much as I expected. In fact, the blade bolt could *almost* be passed right through the 710mm blades when they were outstretched!

So going on the advice of others who've sanded off a small amount of their blade's roots, I clamped the two blades together through the bolt hole, and used a bench-mounted disc sander to carefully sand away the root of the blade, mm at a time. I used the bolt which was holding the blades together as a pivot by sinking it into a hole in a block of wood underneath - this meant the resulting curve sanded into the blade would be a perfect arc - allowing the blades to easily fold back next to each other for storage, whilst removing the absolute minimum of material.

This is the result:

and a before and after:

and a shot with them mounted:

After sanding, I sealed the ends of the blade with thin CA, which I then sanded with fine sandpaper, sealed with thin CA again, etc, 3 times.

As it was mainly the < section I sanded off, I barely removed any material – at least material which was obviously necessary to ensure the strength of the blade root. Any thoughts?

CRCR - Hmmm I had considered that, but there's so little metal for the alley key to bite on, I was afraid that reducing the thickness of the head even more would risk the cap socket stripping ... which would be a REAL pain to remove then!

Cheers guys

David

PS. I don't suppose you guys could guess what this is for on the underside of one of the blades? Maybe for balancing purposes? It's a strange soft rubber material - like the sort you would get around baths .... and it's sunken into the blade, so there was obviously a hole there that had been filled in ...

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03-20-2009 01:31 AM  8 years agoPost 91
Griffo

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Melbourne /​Canberra, Australia

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That's odd... perhaps it was for a lighting system? Or an interesting attempt to balance the blades.

Or perhaps the previous owner left the blades on the bench while he was hacking away with his hand held drill. One slip and oops !

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03-20-2009 01:35 AM  8 years agoPost 92
46Taylorcraft

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AZ

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As it was mainly the < section I sanded off, I barely removed any material – at least material which was obviously necessary to ensure the strength of the blade root. Any thoughts?
Like I said.. with such a small amount of material removed at the end you'll have no issues. You can swing those blades at 1700 rpm 24/7 for a year and they'd never fail at the root.

that silicone plug is there from part of the manufacturing process. Normal.

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03-20-2009 01:39 AM  8 years agoPost 93
Hogster

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That's great to hear, thanks guys!

All that's left now is to fashion the battery tray and charge the batteries!!!

David

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03-20-2009 01:41 AM  8 years agoPost 94
Griffo

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Let us know how you go with the battery tray. I'm also considering upgrading mine using some spare G10.

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03-20-2009 01:45 AM  8 years agoPost 95
Hogster

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Surrey, UK

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Mine needs to go on the boom as the heli's sporting a front mount! Some head-scratching and sketch-drawing are in order!

David

PS. Another little dilemma ... when the blade sits in the blade grip, there's about a 0.5 -> 1mm gap between the top of the blade and the grip. I can put a washer in there, but then the blade bolt doesn't penetrate into the nyloc nut far enough to lock sufficiently well ... if I don't put the washer in it's just acceptable .... any thoughts? Thanks ever so

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03-20-2009 01:46 AM  8 years agoPost 96
Oyley

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Manchester (UK)

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Plug in blade

David...is there some sort of balancing weight behind that plug?

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03-20-2009 01:47 AM  8 years agoPost 97
Hogster

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Surrey, UK

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Allan - Hmmm not sure, quite possibly though - it looks to be around the blade's CofG. Do you want me to poke it to find out?

David

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03-20-2009 04:08 AM  8 years agoPost 98
nooobs

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web

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...

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03-20-2009 06:56 AM  8 years agoPost 99
theslayer

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Munich-Germany

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That rubbery thing is for sure, where the blade got balanced. as far as i know, they put some weight in there and then stuff it with the rubber-stopper... No need to worry bout it

Daniel

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03-21-2009 03:29 AM  8 years agoPost 100
Oyley

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Manchester (UK)

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poke

Hi David...far be it for me to suggest where you 'poke' around,but all young guys like to experiment...so feel free to follow your instincts just be careful with any pics you choose to post with your results....lol

I still believe you may find some weight behind that silicon plug,in fact...you may have inspired me to find an old blade and have a poke around myself......

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