Estes Mini Heli question...

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Alan R

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Instructions say to cut 3 slots in the upper part above the hinges.
I read all of it, looked at the pictures, and looked at build threads, but ... what are these for?
Is this strictly for exhaust? Do you need all that?
 

neil_w

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Paging neil_w , got your ears on?
Oh man, I had *just* fallen asleep.
1615000733381.png


Anyway: yes, they're just for exhaust. I imagine they are indeed quite a bit bigger than needed, but it can't hurt. Of course, the way I'm building mine, they'll end up quite a bit smaller. I'm hoping mine won't blow apart. We shall see!

If I were building it stock, I'd leave the slots as-is, but if they were smaller it'd probably be OK too.
 

kuririn

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Sorry Neil.
It was rocket related, so high priority.
;)
 

Alan R

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glad i posted the question. came across this:
 

Alan R

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Gave it the drill bit and a CA edge... drilling cardboard doesn't really work that well.
IMG_0601.JPG
 

BEC

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I modded a couple of these for contest use. One of the things I did was shorten the tube above the hinges and use a single-hole paper punch to punch the holes.

The ejection charge has to get out somehow (after it cooks the burn string that holds the blades closed). That's what the vents are for.
 

GlenP

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Cutting the slots per instructions creates a pretty weak spot on the tube, would probably not survive a lawn dart, I like your choice of three holes instead.
 

Alan R

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The ejection charge has to get out somehow (after it cooks the burn string that holds the blades closed). That's what the vents are for.
Makes me think you could just use a booster motor instead of a charge. lower the string just above the motor and it would burn, no ejection needed
this was probably part of my confusion. I didnt realize the recommended motor had a charge. I was just expecting a booster that did the burn.
 
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kuririn

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Makes me think you could just use a booster motor instead of a charge. lower the string just above the motor and it would burn, no ejection needed
The booster blowby gasses still need to be vented.
The pressure is not as much as an ejection charge but still need to go somewhere.
 

Rktman

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Other reinforcement options would be to add support ribs like with Apogee Components' Heli-Roc, or strengthen the vent area with a coupler.
 
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Alan R

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Flew the heli today. Beautiful flight, popped open and worked great. Long descent time, fun to watch.

When it finally landed I noticed I have burnt wings. These are from the thread holes.
Anybody else experience this?

friend suggested I just glue a little patch of tin foil at those burn points.

I searched but couldnt find any reference to this problem. The one is actually pitted pretty deep.
any other ideas?


IMG_0677.JPG
 

BEC

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Yeah, it happens. No need to patch at least until they burn through on repeated flights. Don't tie the blades down quite so tightly against the body with the burn thread next time you fly it. Just keep the blades closed.
 

BABAR

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Flew the heli today. Beautiful flight, popped open and worked great. Long descent time, fun to watch.

When it finally landed I noticed I have burnt wings. These are from the thread holes.
Anybody else experience this?

friend suggested I just glue a little patch of tin foil at those burn points.

I searched but couldnt find any reference to this problem. The one is actually pitted pretty deep.
any other ideas?


View attachment 460569
Yuppers, that’s what happens with balsa next to vents.

options.

spray adhesive and a little aluminum foil over the area exposed.
or at launch maybe a piece of tissue type wadding “trapped” between the blade and the hole.
not sure where the burn string is on this model, you could try a double half moon baffle between the burn string and the vent holes.
 

Rktman

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Flew the heli today. Beautiful flight, popped open and worked great. Long descent time, fun to watch.

When it finally landed I noticed I have burnt wings. These are from the thread holes.
Anybody else experience this?

friend suggested I just glue a little patch of tin foil at those burn points.

I searched but couldnt find any reference to this problem. The one is actually pitted pretty deep.
any other ideas?


View attachment 460569
Common problem with helis using burn string retention. The foregoing suggestions are solutions that work or at least minimize the problem. You could also epoxy a thin piece of aluminum from a beer or soft drink can to protect the area. Makes it really bullet-proof.
 

Alan R

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Common problem with helis using burn string retention. The foregoing suggestions are solutions that work or at least minimize the problem. You could also epoxy a thin piece of aluminum from a beer or soft drink can to protect the area. Makes it really bullet-proof.
I think I would use this as a learning experience for future builders. If you wait until the wings are attached to cut the thread hole, you could place the holes between the wings. You still might get a bit of char on one edge though (like the pic above).
Another idea would be to make that hole as small as possible just using a needle. I think that would really minimize the problem as well. I could do that next time myself, just put a piece of tape over the hole (maybe use aluminum tape?) and then poke through
 

neil_w

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Or you could build my version without the burn string!*



*not yet proven to work. :)
 

Alan R

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Or you could build my version without the burn string!*
I've been watching your build. Good engineering. But I think I was way ahead of you when I did mine. Also my first heli, so I didn't know enough to do any experimenting
 

neil_w

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I know, just joshing. But you were talking about how to do a future build. Also my first heli, somewhat out of character for me to start nodding before I’ve gotten a stick build under my belt, but I couldn’t resist.

By hook or by crook I’m gonna get that thing into the air this spring to see if it works. The only real question in my mind is whether it’ll hold together.
 

Alan R

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Also my first heli, somewhat out of character for me to start nodding before I’ve gotten a stick build under my belt,
Ya I'm not that brave. This is one of the most complicated builds I've ever done. Tricky little bugger.

All I can say is I built mine to spec, airfoiled the blades, used elastic thread. I drilled the exhaust holes instead of cutting slots, something I learned from research here. People had said those slots were a problem.

Went straight up maybe 500' I dunno. popped and heli'd nicely down. It's a really nice slow descent.
 
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