CAD design for landing gear

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WARPilot

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I have a WAR FW190 that has landing gear issues. I have decided I should do a deep dive and fix the issues. There are strut problems and general looseness that is incurred due to the budget design.

I think the WAR oleo strut should be ok with some improvements such as hard chroming the strut. There may need to be an additional O-ring or two to help seal. Bushings are needed at the trunnion without enlarging the trunnion. So the gear pivot point will have to be reduced to accommodate the bushing.

The current retract system uses a worm drive that also needs attention.

Are there any CAD guys here that would creat the design? It would need to retract with no binding with the constraints that are imposed by the gear angles.

I am about to trace the gear drawing from the plans. I’m hoping the gear can be simplified some and possibly lose a pound or two.
 

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WARPilot

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The airplanes weigh about 1000#. Of course I need wall thickness as thin as possible but with safety factor.

Should I use hydraulic pipe?

The current WAR trunnion is only 3” wide and approx 2 1/4”. I’ll have actual dimensions when I look at the plans.
 

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dog

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pazamays book on landing gear
and the tubeing is called "mechanical tube' or seamless DOM,nice stuff to work with
 

Soehlig

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I was working on something similar for my design. Retracts based on the 190.
 

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WARPilot

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pazamays book on landing gear
and the tubeing is called "mechanical tube' or seamless DOM,nice stuff to work with
I ordered the book
 

gtae07

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Your thread title suggests you just want someone to make drawings from an existing design.
Yet your text says you want someone to resdeign your gear and do some actual engineering work.
There's a big difference between the two.
 

WARPilot

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Your thread title suggests you just want someone to make drawings from an existing design.
Yet your text says you want someone to resdeign your gear and do some actual engineering work.
There's a big difference between the two.
I think the basic design is OK…..it was designed in the 70’s so surely there are better analysis tools that can help with materials and kinematics. I’m redrawing from the plans and “visualizing” what might be better.
Im sure there will be some re-engineering needed.
 

cblink.007

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so surely there are better analysis tools that can help with materials and kinematics. I’m redrawing from the plans and “visualizing” what might be better.
Im sure there will be some re-engineering needed.
There are plenty of good engineering tools in the open source world at your disposal. FreeCAD is a great design tool, and is FEA capable. You can even animate assemblies. I am using it on my own aircraft design....which has retracts. Pazmany's book is great!!

If you think a sort of re-engineering is in order, although you are asking us (several of us being engineers ourselves), I would advise retaining & consulting an engineer accordingly. Not that we may be full of crap, but without any of us being eyes-on/hands-on your project, anything we say can be pure conjecture at best. Insurance adjusters tend to look unfavorably on things that have failed as a result of advice given from the internet. It's only an airplane...with you in it.
 

WARPilot

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You answered your own question
The wheel axle has issues(strength), the trunnion area definitely has issues(wear and narrowness), alignment of the side brace when in motion is an issue, the gear leg/ole system needs some improvement.
The basic system works but it has been problematic.
 

wsimpso1

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Triple degreed 38 year experienced engineer, with experience turning concepts into working product made in production.

What currently exists is called a concept or a sketch. A design is complete when it has detail drawings for all the parts with materials, raw stock, tolerances, etc. Your design appears to be much closer to the start than to the finish...

A rudimentary analysis of the concept shows some primary weaknesses that must be resolved. You need an engineer who can adjust and size the components, turn them into dimensions that can be made from stock materials, using standard seals, bearings, and brakes with tolerances so they will assemble and hold fluids.

Seek out some engineers, define the work closely around your packaging, load cases (as defined by the FAR's or other engineering study), landing gear loads, weight and cost targets. Get bids. Pick an engineer, and go.

Billski
 

proppastie

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pure conjecture at best
sorry to rain on your parade.....my own experience influences my opinions..I did CAD design for a living, I also worked on the drawing board for 12 years BC (before cad)....I once designed a machine that worked perfectly as delivered from the tool maker.....I should have retired then......Check out the PropPastie product of mine.....there were 7 revisions total with two of them a rework after delivery from my fabricator. If you plan on selling kits you have a big job ahead .....we need people like you .....I wish I had the energy anymore.
 

cblink.007

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sorry to rain on your parade.....my own experience influences my opinions..I did CAD design for a living, I also worked on the drawing board for 12 years BC (before cad)....I once designed a machine that worked perfectly as delivered from the tool maker.....I should have retired then......Check out the PropPastie product of mine.....there were 7 revisions total with two of them a rework after delivery from my fabricator. If you plan on selling kits you have a big job ahead .....we need people like you .....I wish I had the energy anymore.
I was only offering my honest opinion as a credentialed A&P, aero engineer & OEM engineering development test pilot to the OP. My experience heavily influences my opinions as well; I am only imploring the OP to get the right people involved from the get-go....not just solicit advice from a forum. The last thing we all want is for something bad to happen, that's all.
 

WARPilot

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I’m seeking the advice and observations so I can know if there are better solutions or methods from the get go. I’d want to be able to direct the engineer-designer from a more knowledgeable position.
 

wsimpso1

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The stock you build from has to be standard materials.

Oleo-pneumatic struts need to use COTS seals rated for the oil and pressures you intend to run, using sufficient preload and interferences, as defined by the seal manufacturers. Their manuals also will provide surface finish etc needed for grooves and sliding surfaces.

If you are using airplane wheels and brakes (a good idea) standard airframe axles are also a good idea.

Bushing design for mechanism pivots must be designed around worst case landing loads. There are a bunch of cases detailed in Paz‘ book from the FARs. Among them are the bottom of a landing from max vertical speed with spin up loads, max braking, and max side loads. That the base design has apparent weaknesses in the axle and main pivots indicates the designers did not cover all of the cases. You must cover those cases.

Have fun.

Billski
 

wktaylor

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In addition to others insight-filled comments... WAR design appears to have multiple complicating factors...

'Scaled-down to look authentic'... not necessarily a good design solution.

Retractable implies a range of added design problems for reliable motion... tolerances/alignment being a critical element for wear-n-tear.

Maintenance/inspection of the 'original design' and of any 'new design' is rarely considered by designers/developers... it's an afterthought.

As a design matures, thru builders EXPERIENCES, the OEM and 'user's groups are good sources of info. What is the.... WAR/USER-groups experience [comments] RE: Your MLG VERSION...??

WAR/USERS often develop upgrades and repair/mod and maintenance suggestions/upgrades... have these been incorporated?

Also, ensure Your MLG was 'made-by-the-book/drawings'. Are You CERTAIN that every part was made using the specified materials/heat treatment and dimensional accuracy [and alignment]? Steel alloys/temper, bronze alloys, aluminum alloys/tempers have have wide ranges of material properties from strength/stiffness, toughness, wear resistance, etc. Likewise what lubricating grease(s) are You using?

IF other USERs and/WAR admit to problems, then get together on this safety-important subject.
 
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WARPilot

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In addition to others insight-filled comments... WAR design appears to have multiple complicating factors...

'Scaled-down to look authentic'... not necessarily a good deign solution.

Retractable implies a range of added design problems for reliable motion... tolerances/alignment being a critical element for wear-n-tear.

Maintenance/inspection of the 'original design' and of any 'new design' is rarely considered by designers/developers... it's an afterthought.

As a design matures, thru builders EXPERIENCES, the OEM and 'user's groups are good sources of info. What is the.... WAR/USER-groups experience [comments] RE: Your MLG VERSION...??

WAR/USERS often develop upgrades and repair/mod and maintenance suggestions/upgrades... have these been incorporated?

Also, ensure Your MLG was 'made-by-the-book/drawings'. Are You CERTAIN that every part was made using the specified materials/heat treatment and dimensional accuracy [and alignment]? Steel alloys/temper, bronze alloys, aluminum alloys/tempers have have wide ranges of material properties from strength/stiffness, toughness, wear resistance, etc. Likewise what lubricating grease(s) are You using?

IF other USERs and/WAR admit to problems, then get together on this safety-important subject.
 
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