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Gear covers
Jan 5^th, 2014 at 1:51pm

Sitting here finishing up my bottle of Jagermeister, I decided to treat this as a new project - the small hurri will fly (?) with or without the gear covers, but they look so neat I don't want to omit them....

The way the gear is set up, the geometry means the wheels are 10 degrees off level with the wing bottom when retracted, angling front to back. Therefore, if the gear covers are parallel to the wing surface when retracted, when the gear is down, the covers will be angled in, front to back the same amount. Huh Sign

Some threads have said there is no discernible drag to the covers when down, some threads have said there is a fair amount of drag.. my thought is simply that they will look like hell if the covers are pointed in. front to back, by 10 deg. Swear Word

The real plane has a drag link of some kind, attached at the upper 1/4 point, which rotates the real gear as it retracts... as shown in the "real" photo.

It's not too hard to attach the cover to the gear leg so that it is free to rotate and stays in place "up and down", what I need is a way "make" the cover rotate the correct amount. a link using that drag arm should be workable, but Help Me

This will involve, I think, more math than I know - i max out at Pie "R" round...so you math guys, including engineers, can pick at this

This is Good

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« Last Edit: Jan 5^th, 2014 at 2:23pm by Fingers »

gear_001_01.JPG (148 KB | 294 )

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Glen

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Re: Gear covers
Reply #1 - Jan 5^th, 2014 at 7:33pm

Finger's it's pie R square Roll Eyes

On a more useful note, I see the wheel's aren't flush in the wells. On the vailly hurri I believe the retract mount is bolted in unevenly so the wheel is flush in the well and the wheel ends up straight when down as well. Perhaps you could try that sort of geometry by putting a few washers under the retracts and trying them up and down. You might come out with a workable compromise.

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« Last Edit: Jan 5^th, 2014 at 7:38pm by Glen »

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Fingers

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Re: Gear covers
Reply #2 - Jan 5^th, 2014 at 8:32pm

Glen wrote on Jan 5^th, 2014 at 7:33pm:

Finger's it's pie R square Roll Eyes

On a more useful note, I see the wheel's aren't flush in the wells. On the vailly hurri I believe the retract mount is bolted in unevenly so the wheel is flush in the well and the wheel ends up straight when down as well. Perhaps you could try that sort of geometry by putting a few washers under the retracts and trying them up and down. You might come out with a workable compromise.

hadn't thought of that because my Vailly the retracts will rotate, so won't require the shims. I will give that a try, although it will move the wheels back when down won't it... mmmmm mayb e bot, maybe will move the wheels forward when down...not a bad thingy

compromise, compromise...

thanks glen

And cake R square, pie R round (unless it's a crisp, kinda pie, then that can be square)

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« Last Edit: Jan 5^th, 2014 at 8:34pm by Fingers »

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stryker Trainer Box Offline Forum User LastOn: Jan 6^th, 2019 Join: Aug 5^th, 2011 Posts: 27 Reputation: 0 New Glasgow Gender: Zodiac sign: Mood:	Re: Gear covers Reply #3 - Jan 5^th, 2014 at 9:09pm Hey Sandy. I wouldn't worry too much about the drag when the gear is down. My P-51 has doors and you do notice the plane slows a lot when you drop the gear. Actually helps on slowing it down for landing.
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Re: Gear covers
Reply #4 - Jan 5^th, 2014 at 9:33pm

stryker wrote on Jan 5^th, 2014 at 9:09pm:

Hey Sandy. I wouldn't worry too much about the drag when the gear is down. My P-51 has doors and you do notice the plane slows a lot when you drop the gear. Actually helps on slowing it down for landing.

my biggest concern is any pitch change when the gear are dropped - some threads say the pitch down is significant... but then, that might null out the pitch up from half flaps... Shocked

and of course i do realize the real Hurri didn't have half flap - 80 deg or nothing Grin

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Re: Gear covers
Reply #5 - Jan 6^th, 2014 at 8:52am

Sandy, flying your Hurri with the gear doors positioned as they are (with large gap between the gear)you will loose/damage the covers as they can rip away...in flight. Or twist to such a degree they won't retract or drop correctly. That is the same design issue I had with my Spit. The gear in the Spit also did not fit deeply enough into the well.
The solution I used is the following;
Assuming the covers are made the same as mine were, (fiberglass) I positioned the centerline(top to bottom) of the covers over a round object ie; pencil, and pushed down on the leading and trailing edges of the cover as I heated the centre with heating gun used for covering material (use glove).

You should be able to get a concave shape as the fiberglass will bend significantly under heat.

The centre of the cover will not be flush to the wing but, the leading and trailing edges of the gear cover will be.

Hope this helps.....

-

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Dan Marchand

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Fingers YaBB Moderator I still got all five! Offline Forum User LastOn: Today Join: Mar 22^nd, 2010 Posts: 3,088 Reputation: 0 Dartmouth Gender: Zodiac sign: Awards: 3 Mood:	Re: Gear covers Reply #6 - Jan 6^th, 2014 at 9:20am yup, that helps Dan, except my covers are plywood......I'll keep it in mind tho...
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waverider Aerobatic Pilot The Great White Flounder Offline Frozen Solid LastOn: Aug 7^th, 2020 Join: Nov 8^th, 2010 Posts: 499 Reputation: 0 Edmonton Gender: Zodiac sign: Awards: 1 Mood:	Re: Gear covers Reply #7 - Jan 7^th, 2014 at 1:32am http://vimeo.com/12005917 http://www.modelaviation.com/howtolandinggear http://www.avweb.com/news/pelican/185674-1.html?redirected=1
Back to top	« Last Edit: Jan 7^th, 2014 at 1:57am by waverider » image_022.jpg (165 KB \| 293 ) image_023.jpg (422 KB \| 310 ) image_024.jpg (32 KB \| 298 ) image_025.jpg (91 KB \| 291 ) image_026.jpg (196 KB \| 293 ) image_027.jpg (112 KB \| 294 ) Brian H "I see no ships" IP Logged

Fingers

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Re: Gear covers
Reply #8 - Jan 7^th, 2014 at 9:31am

dano wrote on Jan 6^th, 2014 at 8:52am:

Sandy, flying your Hurri with the gear doors positioned as they are (with large gap between the gear)you will loose/damage the covers as they can rip away...in flight. Or twist to such a degree they won't retract or drop correctly. That is the same design issue I had with my Spit. The gear in the Spit also did not fit deeply enough into the well.
The solution I used is the following;
Assuming the covers are made the same as mine were, (fiberglass) I positioned the centerline(top to bottom) of the covers over a round object ie; pencil, and pushed down on the leading and trailing edges of the cover as I heated the centre with heating gun used for covering material (use glove).

You should be able to get a concave shape as the fiberglass will bend significantly under heat.

The centre of the cover will not be flush to the wing but, the leading and trailing edges of the gear cover will be.

Hope this helps.....

-

Dan, just realized what your comment was......sorry Huh

The gear cover is not really that proud from the wing - if you look you'll see it's sitting on a stick and a can of paint Shocked

Whatever I do the front of the cover will be flush with the wing surface at least... Smiley

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