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Old 10-12-2017, 02:45 AM   #1
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Default working the Firebolt bowl to fit constant speed prop

I figured I would start a new thread, on my endeavors to "butcher" my Firebolt nose bowl. Making it work with my constant speed prop.

No way can I add spacers to take the prop forward and I am short of room to bolt on accessories like starter motor and alternator.

I have already laminated in a bump out for the stubby starter and now I need to add a bump out for the alternator pulley

I have included this
http://www.biplaneforum.com/showthread.php?t=16094
to show the other problem I had with this nose bowl and a constant speed prop

I started today with figuring out where I needed to cut through. As time goes on I will make a shape to bond to the nose bowl, allowing ample room for the alternator.
A couple of photo's so far.


DSCN6645 (1280x960).jpg   DSCN6646 (1280x960).jpg   DSCN6647 (1280x960).jpg   DSCN6648 (1280x960).jpg   DSCN6650 (1280x960).jpg  

DSCN6649 (1280x960).jpg  
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Old 10-12-2017, 06:52 AM   #2
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Wouldn't that frustrate you. So close yet so far..... now you need a bump


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Old 10-12-2017, 08:53 AM   #3
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Eric, if you intend to fly acro, you'll need more clearance. Probably a minimum of a 1/2". Isolaters sag with time and "G".
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Old 10-12-2017, 10:52 AM   #4
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Originally Posted by race38 View Post
Eric, if you intend to fly acro, you'll need more clearance. Probably a minimum of a 1/2". Isolaters sag with time and "G".

I was going to say the same thing.

Or, you could put an accessory case mounted B&C alternator on there.
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Old 10-12-2017, 11:22 AM   #5
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Originally Posted by race38 View Post
Eric, if you intend to fly acro, you'll need more clearance. Probably a minimum of a 1/2". Isolaters sag with time and "G".
Point taken.
This is what I had.
The bowl off (no way could I install the bowl with the alternator in place).
I measured where the alternator is in distance from the center of the crank. and then drew green lines from the crank to each side of the alternator pulley (with some extra space).

I removed the alternator and then I installed the bowl. Then threw some masking tape down that I could draw on. With a pencil fitted in my big compass I drew the line from center of crank and straight edged the green marker lines from the hub down to the pencil line.

Then drilled the two holes and cut out between.

Bowl off and installed the alternator with belt again.
Installed the bowl and this is what you see.
I think I was lucky to be this close. I didn't want to open up too big an opening.
I would prefer to slowly widen the gap rather than cut out too much on the first go.
Now I can figure out how much and where to widen.

A photo of the cover below
DSCN6644 (1280x960).jpg  
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Old 10-12-2017, 05:58 PM   #6
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Default roughing out my bump out

It was easy to get the shape out the PP mold.
I removed down to some thickness of wall.

Then I used an empty mixing cup to trace the curve of the center of the nose bowl and transferred this to the laminate. I drilled a couple of holes (for no reason I found out!) then used the band saw to remove that segment.
DSCN6652 (1280x960).jpg   DSCN6653 (1280x960).jpg   DSCN6654 (1280x960).jpg   DSCN6655 (1280x960).jpg   DSCN6656 (1280x960).jpg  

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Old 10-12-2017, 06:16 PM   #7
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Slowly trimming down the bump out to fit.
Later I will remove inside the red line. I'll keep a 1/8th edge to butt up the carbon fiber bump out.
DSCN6657 (1280x960).jpg   DSCN6659 (1280x960).jpg   DSCN6660 (1280x960).jpg   DSCN6663 (1280x960).jpg   DSCN6664 (1280x960).jpg  

DSCN6665 (1280x960).jpg  
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Old 10-12-2017, 06:23 PM   #8
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Nice work! I wasn't sure where you were going at first when I saw the mixing cup as a mold...
Fabricator extraordinaire!
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Old 10-12-2017, 06:51 PM   #9
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You'll have some drag on the face of that. Why not convex the face, somewhat....
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Old 10-12-2017, 07:55 PM   #10
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Quote:
Originally Posted by race38 View Post
Nice work! I wasn't sure where you were going at first when I saw the mixing cup as a mold...
Fabricator extraordinaire!

Thanks.

I went looking all around the shop for something I could use as a mold.
This was the best thing found.
It's easy to remove the part, use a sharp blade and slice the plastic and peel away.
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Old 10-12-2017, 08:07 PM   #11
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Quote:
Originally Posted by Beej View Post
You'll have some drag on the face of that. Why not convex the face, somewhat....
I didn't have a mold with a convex bottom. The plastic bucket was all I could find.
With this in mind, as compared to the Skybolt nose bowl I think the Firebolt has less of a gaping, air collecting mouth to cause drag.

During the last couple of weeks, what's been upsetting me is need to butcher the bowl and that has been a drag

Now! If I find half a play ball I could use as a mold, I could make a dome to sit on top Thanks for the idea.
I may go to Walmart with my tape measure tomorrow.
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Old 10-12-2017, 08:17 PM   #12
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a small piece of styrofoam glued on and sanded to shape, some clay, play-do, or even plumbers putty can be used to make a dome shape to form a mold the fiberglass.

Bob
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Old 10-12-2017, 08:36 PM   #13
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a small piece of styrofoam glued on and sanded to shape, some clay, play-do, or even plumbers putty can be used to make a dome shape to form a mold the fiberglass.

Bob
Let me get this rascal stuck on first and then I will look at dolling it up.
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Old 10-12-2017, 09:13 PM   #14
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Originally Posted by taff View Post
Thanks.

I went looking all around the shop for something I could use as a mold.
This was the best thing found.
It's easy to remove the part, use a sharp blade and slice the plastic and peel away.
I might have tried some heat on the bottom of the cup to bulge it a little.
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Old 10-12-2017, 10:33 PM   #15
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I might have tried some heat on the bottom of the cup to bulge it a little.
No you wouldn't........ you would be smashing one out of aluminum......
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Old 10-12-2017, 11:18 PM   #16
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OK, maybe in another life......
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Old 10-13-2017, 02:41 AM   #17
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A couple of photos from this afternoon.
I used a Dremel to trim back to the green line and then drum sanded to finish off.
My Aircraft Spruce order (with West 105) arrived late afternoon, so I went later to laminate the bump out. Tomorrow I will laminate the inside.

As to the aerodynamic dome.

One possibility I am thinking of is sticking on a fake landing light!

What about that?
DSCN6666 (1280x960).jpg   DSCN6667 (1280x960).jpg   DSCN6668 (1280x960).jpg   DSCN6669 (1280x960).jpg   DSCN6670 (1280x960).jpg  

DSCN6671 (1280x960).jpg  
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Old 10-13-2017, 06:12 PM   #18
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Done a little work this morning with the bump out.

Mainly spending time with the aerodynamic dome shape. Got some foam and glued it on and then started profiling.

I had not even finished profiling when I sat back and stared at the thing and said to self "self, this is not what I want" and went and got a saw and cut the foam off.
I will live with a flat front bump out.
It's only a couple of inches causing drag. ( I know, some will say every inch counts)

Anyway a few photo's
DSCN6672 (1280x892).jpg   DSCN6675 (1280x960).jpg   DSCN6677 (1280x960).jpg   DSCN6678 (1280x960).jpg  
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Old 10-13-2017, 08:09 PM   #19
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Now when you have that nose bowl all nice and pretty, wax it up, make a mold off it and vac bag a nice new Carbon one off of it
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Old 10-13-2017, 09:24 PM   #20
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Now when you have that nose bowl all nice and pretty, wax it up, make a mold off it and vac bag a nice new Carbon one off of it
Right now I want that vacuum bag over my head. I am loosing so much profit in this thing (time is money!) Lol.

Tell U wat. I'll send it to U and you can use it as a plug. When you made a few, I'll have one . I am done itching with glass, or I am itching to finish this.

Other thought. Someone can bang one out of aluminum for me (like the old dayz) That would be real nice.

It's up for adoption.
Me. I am just going through the motions to be done with it and get on with building / life.
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Old 10-14-2017, 12:12 PM   #21
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I'm curious why you spot painted the nice rework of the inlet ramps when you knew you were going to chop it up more and do more body work and painting?

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Old 10-14-2017, 01:50 PM   #22
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I'm curious why you spot painted the nice rework of the inlet ramps when you knew you were going to chop it up more and do more body work and painting?

Phil
Hi Phil.
The painting part is easy for me. It's all the guess work, head scratching and development work that wears me down.

I knew I needed to figure out the air ramps and I planned to do that. The need for a bump out was a bit later.
I figured that I would get the ramps complete before starting on the bump out.
I guess it's my way of keeping focused on one thing.
So no big thing. I will spray the whole lower thing in time. I may do a color spot repair on the bump out project first.
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Old 10-14-2017, 02:13 PM   #23
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Yesterday I applied some West fairing filler with resin.

After overnight drying I sanded and applied a thin coat of fresh stuff to fill pin holes and little low spots

If acceptable after sanding I will brush on a coat of epoxy primer (I have a feeling there will be some pin holes) I don't want to spray right now, will cover too much an area with primer and still not fill pin holes.
DSCN6680 (1280x960).jpg   DSCN6682 (1280x960).jpg   DSCN6683 (1280x960).jpg   DSCN6684 (1280x960).jpg  
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Old 10-14-2017, 06:03 PM   #24
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Lots of work on a "premade" nose bowl! Looking great! I'm curious why the Ramps weren't built in to it? I mean if everyone has to do this just change the mold. Same for the alternator clearance.
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Old 10-14-2017, 07:00 PM   #25
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Lots of work on a "premade" nose bowl! Looking great! I'm curious why the Ramps weren't built in to it? I mean if everyone has to do this just change the mold. Same for the alternator clearance.
I have seen the Firebolt nose bowl on Skybolt aircraft and it looks good. Probably with a fixed pitch prop.
But I can not add a spacer under the prop, I have a constant speed.

If there was enough room, The bowl would be further forward and I wouldn't need to cut and add stuff.

If the bowl were further forward Then the ramps would be as usual and no need to cat and make bump outs for alternator and starter.

The Skybolt nose bowl looks like this. (below) There should be no problem with this.
I live and learn. I didn't know this.


skybolt_nose_bowl_white_bg_150x113[1].jpg  
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