Retractable Landing Gear Design and Material

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WARPilot

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Apr 20, 2019
Messages
76
How wide is your wings' center section?
If it is less than the 8 foot trailer limit, you might want to extend its span to include the landing retraction mechanism.
That change will eliminate several variables and potential for jamming. Moving the wing joint farther outboard will also reduce bending loads on the joint, so may allow you to reduce the weight of the straps that span the joint. Again, ask an engineer to review your wing spar changes before cutting any metal.
The center section is 96". The outer panels are 72" each.
My composites engineer friend can calculate the loads.
 

Riggerrob

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Sep 9, 2014
Messages
2,655
Location
Canada
The center section is 96". The outer panels are 72" each.
My composites engineer friend can calculate the loads.

So your 96" (8 feet) center section matches the maximum width allowed on most highways.
How much can you reduce the center section span if you tilt it on a trailer? A few Formula 1 racers were trailered intact, albeit tilted at a steep angle. Consider that the average Formula 1 is only 4 or 5 feet tall from tail wheel to the top of the fin.
I am trying to suggest ways to simplify your wing center section and avoid the gap in the retract mechanism.
 

WARPilot

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Joined
Apr 20, 2019
Messages
76
What gross weight, wing area, fuel location, engine weight, Vs, Vd, etc., will you use to calculate the loads?


BJC
Here is what I'm thinking with consideration of input from this thread.
gross weight..............................900#
Fuel, Header Tank 14 gal............85#(possible 6 gal belly tank for XC flt)
Engine/Prop, FWF......................200#(220#)
Vs Slow as possible, No Flaps..50-60mph Flaps add some complexity and expense with little gain on lowering the stall, IMHO.
Vd(Vne)......................................200-220mph
Vc..............................................165+mph(180 goal)
HP....................all engines ........110hp-140hp
EOW......................................... 550-570#

Engines. Rotax 914T(114hp), 915i(141hp), UL Power UL350iS(130HP), D-Motor?, AC Aero Swift FL150?, Verner 7U*
Pilot weight 180-225#
Im 5'10" and it is tight but we could probably add minor cockpit increases
Seat back would have a notch for a 14# parachute
Flight Controls...Fabric and balanced

* using the 7U forces small upscaling due to diameter
Carbon Fiber Spar designed for 9g Ultimate

EOW.......560# Airframe 275# + Gear/Metal 65# + Avionics/Misc 10# + Engine/Prop 210#
Pilot........225#
Fuel........85#
total. 870#. Add parachute 885#. Add baggage 15# = 900#
 

WARPilot

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Joined
Apr 20, 2019
Messages
76
Here is what I'm thinking with consideration of input from this thread.
gross weight..............................900#
Fuel, Header Tank 14 gal............85#(possible 6 gal belly tank for XC flt)
Engine/Prop, FWF......................200#(220#)
Vs Slow as possible, No Flaps..50-60mph Flaps add some complexity and expense with little gain on lowering the stall, IMHO.
Vd(Vne)......................................200-220mph
Vc..............................................165+mph(180 goal)
HP....................all engines ........110hp-140hp
EOW......................................... 550-570#

Engines. Rotax 914T(114hp), 915i(141hp), UL Power UL350iS(130HP), D-Motor?, AC Aero Swift FL150?, Verner 7U*
Pilot weight 180-225#
Im 5'10" and it is tight but we could probably add minor cockpit increases
Seat back would have a notch for a 14# parachute
Flight Controls...Fabric and balanced

* using the 7U forces small upscaling due to diameter
Carbon Fiber Spar designed for 9g Ultimate

EOW.......560# Airframe 275# + Gear/Metal 65# + Avionics/Misc 10# + Engine/Prop 210#
Pilot........225#
Fuel........85#
total. 870#. Add parachute 885#. Add baggage 15# = 900#
I have a WAR FW190 that currently weighs 760# EOW. Lifts off the ground at approx 70mph, stalls at 65-66mph. Cont O200 with 3bladed whirlwind prop top speed 165mph. They are complex builds these days and could be improved fairly easily.
 

WARPilot

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Joined
Apr 20, 2019
Messages
76
What gross weight, wing area, fuel location, engine weight, Vs, Vd, etc., will you use to calculate the loads?


BJC
I have a WAR FW190 that currently weighs 760# EOW. Lifts off the ground at approx 70mph, stalls at 65-66mph. Cont O200 with 3bladed whirlwind prop top speed 165mph. They are complex builds these days and could be improved fairly easily.
 

Riggerrob

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Joined
Sep 9, 2014
Messages
2,655
Location
Canada
Dear WARpilot,
A typical back type pilot emergency parachute measures 24" by 16" by 3" (Strong 303 back PEP). They also offer a 311 Wedge that is still 24" by 16" but is 1" thick at the top swelling to 3.5" thick at the bottom.
... which is why I suggest building the rear cockpit bulkhead vertical, then adding a parachute or seat back cushion to adjust for pilots with different leg lengths. Back type PEPs weight 16 to 20 pounds.
Hint: I stand 6' tall, weight 210 pounds naked and have 32" inseams and am cramped in a stock WAR Sea Fury cockpit. Even a bit more knee room and elbow room would help. How much extra elbow room can you add in a carbon fiber, composite, moncoque cockpit?
 

WARPilot

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Joined
Apr 20, 2019
Messages
76
Dear WARpilot,
A typical back type pilot emergency parachute measures 24" by 16" by 3" (Strong 303 back PEP). They also offer a 311 Wedge that is still 24" by 16" but is 1" thick at the top swelling to 3.5" thick at the bottom.
... which is why I suggest building the rear cockpit bulkhead vertical, then adding a parachute or seat back cushion to adjust for pilots with different leg lengths. Back type PEPs weight 16 to 20 pounds.
Hint: I stand 6' tall, weight 210 pounds naked and have 32" inseams and am cramped in a stock WAR Sea Fury cockpit. Even a bit more knee room and elbow room would help. How much extra elbow room can you add in a carbon fiber, composite, moncoque cockpit?
The softie parachute advertises a weight of 14# for up to 240 person.
I’m thinking of 1/2 inch wider at shoulders and a couple of inc hips to rudder pedals. I don’t think it is possible to go lower but one might gain another 1/4” down and possibly slightly enlarge the canopy to gain another 1/4”tall. I’d have to get with my composites friend and see if adding an inch length forward and maybe two aft to pick up so e room. Changing the design introduces other complications and analysis so keeping them to a minimum is important.
 

WARPilot

Well-Known Member
Joined
Apr 20, 2019
Messages
76
Dear WARpilot,
A typical back type pilot emergency parachute measures 24" by 16" by 3" (Strong 303 back PEP). They also offer a 311 Wedge that is still 24" by 16" but is 1" thick at the top swelling to 3.5" thick at the bottom.
... which is why I suggest building the rear cockpit bulkhead vertical, then adding a parachute or seat back cushion to adjust for pilots with different leg lengths. Back type PEPs weight 16 to 20 pounds.
Hint: I stand 6' tall, weight 210 pounds naked and have 32" inseams and am cramped in a stock WAR Sea Fury cockpit. Even a bit more knee room and elbow room would help. How much extra elbow room can you add in a carbon fiber, composite, moncoque cockpit?
 

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WARPilot

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Joined
Apr 20, 2019
Messages
76
So your 96" (8 feet) center section matches the maximum width allowed on most highways.
How much can you reduce the center section span if you tilt it on a trailer? A few Formula 1 racers were trailered intact, albeit tilted at a steep angle. Consider that the average Formula 1 is only 4 or 5 feet tall from tail wheel to the top of the fin.
I am trying to suggest ways to simplify your wing center section and avoid the gap in the retract mechanism.
If it could be trailered at 40-45 degrees, then an 11.5’ center section is possible.
 

WARPilot

Well-Known Member
Joined
Apr 20, 2019
Messages
76
So your 96" (8 feet) center section matches the maximum width allowed on most highways.
How much can you reduce the center section span if you tilt it on a trailer? A few Formula 1 racers were trailered intact, albeit tilted at a steep angle. Consider that the average Formula 1 is only 4 or 5 feet tall from tail wheel to the top of the fin.
I am trying to suggest ways to simplify your wing center section and avoid the gap in the retract mechanism.
One good thing about going to a wider center section, if flaps were added, they would be of a more meaningful span.
 

Vigilant1

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Joined
Jan 24, 2011
Messages
7,804
Location
US
One good thing about going to a wider center section, if flaps were added, they would be of a more meaningful span.
Just an opinion, but I'd go the other way and make the center section a bit shorter to allow >much< more convenient trailering. I don't think folks looking to build this kind of plane will miss a bit of flaps, and it won't make a big difference in approach/stall speed.
Whether folks will actually move their plane frequently by trailer hardly makes a difference. Many think/dream they will, and that can help convince some buyers. Hangar space isn't getting cheaper or more available.
 

Sraight'nlevel

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Joined
Nov 4, 2021
Messages
304
Here is what I'm thinking with consideration of input from this thread.
gross weight..............................900#
Fuel, Header Tank 14 gal............85#(possible 6 gal belly tank for XC flt)
Engine/Prop, FWF......................200#(220#)
Vs Slow as possible, No Flaps..50-60mph Flaps add some complexity and expense with little gain on lowering the stall, IMHO.
Vd(Vne)......................................200-220mph
Vc..............................................165+mph(180 goal)
HP....................all engines ........110hp-140hp
EOW......................................... 550-570#

Engines. Rotax 914T(114hp), 915i(141hp), UL Power UL350iS(130HP), D-Motor?, AC Aero Swift FL150?, Verner 7U*
Pilot weight 180-225#
Im 5'10" and it is tight but we could probably add minor cockpit increases
Seat back would have a notch for a 14# parachute
Flight Controls...Fabric and balanced

* using the 7U forces small upscaling due to diameter
Carbon Fiber Spar designed for 9g Ultimate

EOW.......560# Airframe 275# + Gear/Metal 65# + Avionics/Misc 10# + Engine/Prop 210#
Pilot........225#
Fuel........85#
total. 870#. Add parachute 885#. Add baggage 15# = 900#

That is 7%.


Little too high...normally 3-5%.
 

Tom DM

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Joined
Mar 31, 2022
Messages
197
Location
EBGB Grimbergen airfield (N of Brussels, Belgium)
For thirty years I was on the lookout for ideas leading to a feasable 103 legal UL
retract gear certainly to use in a land configuration but expecially for the 103 seaplane
configurations. There were some interesting retracts for the float UL planes and the hull based UL planes and I remember a few for the amphib Trikes as well. In the museums there were some old old amphib seaplanes that allowed close up shots of their amphib gear. I also remember a Trike that looked like a streamlined bullet when its gear was retracted. One of the funniest retracts was on the UL Buchaneer where the pilot reached down and plugged in or unplugged the gear leg on each side and
tossed the gear leg and wheel into the fuselage when airborne. Somewhere there is a folder with the name "retracts" and maybe I can find it. I never looked at the Mooney Mite or the BD-5 that I can remember but I will be looking them up. Thanks.

F-PJKV 1962 french Maurice Paumier Baladin.

I have the plans and the airplane (S/N001). Retracts all wheels via 1 lever, cable and pulleys operated, no hydraulics. I will scan the concerned portions of the plans and wll e-mail.

When the wheels retract, it ceases to be a plane, it becomes a bird.
 

Malish

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Joined
Oct 11, 2013
Messages
783
Location
Russia. City of Volgograd
Current WAR landing gear, spring type, design. The trunnions are not depicted but need reinforcement and or a sacrificial bearing added. The steel tubing seems well overbuilt where it goes into the trunnion.
Then there is the retract system itself. It needs to be smooth, lighter, and simpler.

Do you have complete drawings for this landing gear system or know where to get them? One person I know designing replica of Yak-3 aircraft and interested to get more info about this landing gear, he think it's will work very well in Yak-3 replica.
IMG_20220521_144412.jpg
 
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