Help With Tail Clearance

scottessex

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The Saga continues.......
I have the heintz 57 gyro mocked up, here is what I have in the pictures you can see the tail to rotorblade clearance.

How much is enough? I know that the blades will be flexed upwards in flight. The pics were taken with the blades all the way back against the stops.

Rotorhead Question. I noticed that the Dragon wing hub bar botoms out on the main bolt, instead of the teeter stops! Is this normal for a bensen head?
or is this a set of new problems?
 

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scottessex

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rotor head pics

rotor head pics

Here are the pics of the rotor head.

By the way, those are the 25ft Blades I got from Chuck, they don't look like they'll hit the ground.
 

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Jonvee

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Hub bar touching

Hub bar touching

That is what happend with my Rotor Hawk head and Dragon wings. The deal is that Ernie puts a bend in the hub bar for coning relief. This allows the bar to teeter a few more degrees before it contacts the stops of a Standard head. You can glue a piece of rubber or plastic to the bottom of the hub bar to act as an extra bumper. I just purchased a new head from Ernie. It has twice the fore/aft movement than my old head. I had to make new cheek plates to raise the head to get more clearence to the tail. Once I got a hold of the new head I understood why the Dominator is so damn tall. The new head also has taller towers. It also is as smooth as glass. The Dominator plans that I refer to when I make my modifications show a 1" clearence from rotor blade to tail. It seems kind of close when you look at it but I never push the blades on take-off so they would come near the stops. I also pre rotate before I taxi. Does anybody know the teeter angles during a fast take-off? I think in level flight it has been said the blades teeter about four degrees.
 
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Chuck Irby

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Scott, that small amount of clearance bothers me. I think it should be more like 6 inches.
 

Screw

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Screw-In

I don't anything, but I agree with Chuck. It looks like your mast needs to be taller by about 6 inches. As far as the head goes, you be safer buying one of Ernies heads.

Screw-Out
 

Chuck Irby

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Scott, I was thinking more like readjusting the head to give you adequate Clearance (whatever Ernie, or someone who really knows suggests) then drill the holes in the cheek plates. It looks to me like the mast may be tall enough. Then like Jonathan suggested, maybe some sort of protector between the bolt heads and the hub bar.

Have you hung it yet, Scott?
 

Chuck Irby

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Mike Gaspard in Chux Dom

Mike Gaspard in Chux Dom

Scott, this might help with ideas.
 

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Chuck Irby

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Scott, I just noticed something else in the pic of the whole machine. Your horizontal stab is several inches above the center of the prop flange. Can you cut off the bottom of the tail? If so, this would give you more clearance. BTW, that is one fine looking piece of tail. :D
 

rehler

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Scott,

I know you want it to work as is, but the clearance shown in the photos is way to little! Sure 98% of the time it should work, but one time if you get a little flap on take off (I did it today - going a little too fast and the blades had slowed down while taxing onto the runway) and it will probably hit. It's not worth the risk. The easiest thing to do is just make new taller cheek plates.
 

Screw

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Screw-In

No Doubt Chuck, I didn't even notice but your right. If Scott cuts off the bottom of the tail enough to drop the horizontal right in the center of the prop wash, that will probably give him the clearance he needs between the tail and the blades without changing the height of the mast. Good eye chuck!

And in doing so will lower the top of the tail and make the angle between the blade and tail close to parallel.

Screw-Out
 

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Brent_Brown

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Scott do you have the prop?

I would like to see where it plays in all this.

Did you drill the lower keel for this location.

It looks like it can come forward an inch. Not sure without the prop on and rudder in full right or left input.

Before you cut the tail or make new plates call me.

I think it will work as is. unless you think the HS to high but a lower tail might put the upper support into the prop then you got the dog leg thing.
 

Jamie Cleary

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Hi Scott,
I am not certain by the pic but it appears that you
have the hub bar in the wrong hole? According to
Ernie the bottom hole is for the Bensen style head,
that may help with bolt clearance, additionally you
want to check the bolts that secure the blades to
the hub bar on my AirCommand the first one or two
had to be put up from the bottom to get adequate
clearance on the Wunderlich pre rotator.As far as
the clearance on the tail all I can say my 503 CLT
Air Command the prop to rotor clearance is so close
it's scary and I have some first hand knowledge it
will hit if you try hard enough!!!!!!!!
 

scottessex

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Thanks guys,

I am still waiting on the prop.

Brent I will call you when I get the prop.
Also yes I drilled the keel, but it is the old keel, I have a fresh piece of 2x2 to drill up once everything is finalised.

I put the rotor blades on and the bolt goes into the bottom hole just like on John Stevens brock head.
I had a set of taller towers made 1" taller, I can get the bolt through the 3rd hole on the dragon wings hub bar. But it changes nothing except the pivot height.
 

Brent_Brown

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You can camp a wood 1x2 to the motor just for size and see how it looks.

The HS high or low 2 or 3 " is no big deal
 

automan1223

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Build questions

Build questions

Scott,

Clearance looks snug but might be ok once you set the max teeter stops at I think 17-18 degrees total travel, and the rotor head at 9 degrees back total.

If the teeter has 18 degrees and it should be ok, if it does not have 18dg then you want to make sure the hub bar does not contact the main bolt. You will have to rework the hub bar or mill a slot in it or turn the head of the bolt down a tad. Neither option is the best action.

You can with a nights work make a new plate with longer ends to bolt to the top of the bearing block assy. to set your teeter limits.

Concur With brent dont cut any tail yet.

Flap is concern but you should have a prerotator to take care of that anyway.

Jonathan
 

scottessex

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Can I mount just the hub bar with out blades, in the rotor head and check how many deg. travel? How about 1/4" spacers under the teeter towers to get them off the head? A No No?
I will be taking my tape measure to ROC!
 

Chuck Irby

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Hmmmm, yes to the hub bar by itself. I can't properly answer the spacer question.

If the tail can be cut off on the bottom, without any real problem, that's the way I'd go. That tail is pretty tall, Scott.
 

ben

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scott i'm having the same trouble with dragon wings my teeter tower are 1 1/2" taller then standard for undersling reasons and now i have 33 degs teeter in them hard to figure where to put the tall tail i'm building. i'm thinking about building up my stops on the rotor head.
 

automan1223

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rotor 101

rotor 101

there are many ways to limit travel in the teeter area. My only concerns about spacers are that they have to be secure and that means drilling holes, securing hardware etc. My method is while you are going to do that, why butcher a good part, just make another one made right from the start. If you are unsure then make it a bit larger and tune it down from there.
 

scottessex

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What I meant was machining a small, 3/8 or 1/2 inch spacer out of barstock that sits under the tower. I guess that would work for set up.
 
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