mschneider2005

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Hey Guys,

This posting is for TF 310 owners who have been thinking about adding sequenced inner gear doors to their airplane. I have been following the 310 threads for quite a while now and I haven't really seen a good explaination on how to make the inner gear doors work. After many hours of racking my brain.. I've come up with an easy solution. I will list the parts I used and give step by step instructions with photos. The most difficult part is getting the air cylinder to fit in the space and have enough throw to open the door wide enough to let the wheel clear. I've expermented with a workbench mockup system and figured out all the dimensions and throws. Using a 1/2" stroke air cylinder, the door will open a full 90 degrees. The total cost is about $150.00 and it's really cool.

mschneider2005

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Here are the basic parts:

*Du-Bro Large Nylon Hinges #257
*Du-Bro 2-56 Rod #801
*Great Planes Ball link Set #GPMQ3841
*Du-Bro 90 Deg Bell Crank set #167
*Du-Bro Aileron wire set #556 (Only the Nylon parts are used)
*Ultra Precision UP2 Retract valve
*AirPower Lightweight Geardoor Cylinder - 1/2" Stroke
Air line
Robart QD a total of 4 sets.

mschneider2005

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The first step is to hinge the doors. I used the large Du-Bro hinges. I used my sanding drum on a dremmel to grind out the fiberglass in the are that the hinges will be epoxied. They need to be recessed so the hinge pin is centered on the edge of the door. I'll post a photo with a ruler for dimensions. The gear doors are curved but the hinges cannot follow the curve. They need to be potted in at an angle to they are in a stright line relaitive to eachother.

mschneider2005

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The second step is to install the door stops inside the wheel well to prevent the door from falling all the way in. You want to CA or Epoxy them in such a way that the outer surface of the gear door is smooth and flush with the rest of the wing. The right an left doors look the same, but believe me, they're different. If you get them backwards, you'll never get them to sit completely flush.

mschneider2005

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Once you’ve attached the hinges to the doors and installed the door stops, you’re ready for the next step.

Lay the door in the stops centered from front to back with the hinges laying flat on the wing. Carefully mark the location of the hinge pin, not the whole thing. Cut and remove the small portion of wood between your marks and the fiberglass wheel well.


Test fit the hinges in the slots and cut as much of the fiberglass wheel well as needed to accommodate the hinge. You want the door to sit flat and flush with the wing panel. Epoxy in when satisfied. Don’t forget to oil the hinge so the epoxy won’t gum it up. You want the door to flop open and closed as smoothly as possible.

I’ll take pictures tonight and post them tomorrow.

Here is a cross section drawing:

mschneider2005

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While the epoxy is curing, you can start on the actuator.

Install a ball link in the inner hole on one side of the bell-crank and the outer hole on the other. Install a cup on the end of the air cylinder. Cut off the two unused holes on the short side of the bell crank. Be sure you make a right and a left!

mschneider2005

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Epoxy a small hardwood pad to the inside of the wheel well near the bottom right up against the 45 deg. bend. The pad should be about as thick as the bell-crank bearing. It helps to pre drill a hole in it for a servo screw since its hard to work at the bottom (top) of the wheel well. I used a lighter to heat up a t-pin and pushed it through the fiberglass to make a starter hole.

mschneider2005

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Mount the bell crank short side down right in the corner where it can swing close but not touch anything. I epoxied the bearing and used a wood screw to install it bellcrank. Make sure you cut off the tails of the ball links so they won't rub. Make minor adjustments to allow clearance and full extension and retraction of the shaft on the air ram.

mschneider2005

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The last step is to make a small final rod using two ball cups and short piece of 6-32 all thread rod. Add a ball to the nylon alieron links and make the final adjustments. Once you have every think hooked up to the UP2 valve, it should sequence perfectly. I'll post a video once I finish the other wing.

orvel

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mschneider, I don't know why you had to go through all that trouble of installing bellcrancks and stuff. Here's a few pictures of my setup using 1" stroke BVM cylinders hooked directly to the doors. They work like a dream, no problems at all! I also mounted the cylinders on removable panels secured by screws that allow full and easy access to the air lines.

DAN AVILLA

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I did mine with tams offset hinges. Dan

mschneider2005

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Orvel,

That is a nice set up. This set up was actually my second design. My first set up was using the same rams pushing the door open from the back side. It worked well for about 50 cycles, but eventually one door would not close all the way. (see photo) When I redesigned the set up I started again from scratch.

I wasn't able to get BVM 1" stroke air cylinders, I had to use my Tamjet 1/2" stroke. They are too long to stand upright and the stroke is too short to open the door from an angle. If I go through the set up again in the future, I'd use 1" stroke rams like you did. Looks great!

mschneider2005

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Dan, your hinges look good too. I though about using off set hinges, but I couldn't figure out a way to access the back side of the wheel well with out cutting a hole in the top of the wing right at the spot where they always crack. How did you get around that problem?

DAN AVILLA

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As you can see from the picture the cracked wing. That was my first set. The second set I glassed but still if you land real hard they will crack at the back of the pocket. They did not crack were I cut the hole for the hinge. Because the hinge has predrilled holes I made a piece of plywood fit the hinge and cut out the sheeting and inserted it. I cut off the flaps and layed carbon cloth the full length of the flap hinge area to stop the cracking. Then rehinged. Thanks Dan

DRMRJON

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Has anyone figured out how to set up the nose gear door? I have been searching around with no luck.

thisoldman

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did you make your doors out of glass. Have been looking at your setup.

orion4455

Hello Orvel:
I purchased a cessna 310 with robarts and downandlocked this past april. i was looking at your pictures and info on sequenced inner gear doors. what wheels and tires are you using? they look awesome! also, any new ideas on how you would do your hinges now that its three years later since you did you gear doors? im looking at types of hinges and doors to use. dont want to buy a whole set of doors for just three doors, but may have to. fill me in if you get a few minutes...best, orion4455, and mucho thanks for sharing your ideas and pictures.

orion4455

Hello Orvel:

I am revisiting the idea of making or buying landing gear doors for my 310. i would like to buy the doors, but i would be forced to buy an ENTIRE set at $60.00. do you have any ideas regarding the purchase of the three main doors to the set ( the big ones in topa1671).
i would use about 9g servos, futabas, with the downandlocked.com electric board. Also, want HINGES that are clean, simple. any ideas would be appreciated from you or any of the guys who have wrestled with this area of doors.

i welcome all input. thank you. orion4455.

orvel

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Orion, other than making the doors yourself out of fiberglass or 1/8 plywood/ balsa I don't see how you get around the issue of not spending the 60 bucks, that's retailing in this hobby! I can tell you that those doors would be real easy to make, there's really nothing to them and that is what I would do if I ever needed to! If I was shopping around for hinges today I would probably use those offset ones specifically made for LG doors, I had those multipurpose ones at the time and that's what I used. Regarding the tires, I bought them from a primarily RC Jet supplier, I believe it was Northern Hobbies but I'm not 100% sure anymore since it's been awhile, I'll try to see if I have some further info and if I do I'll let you know!

orvel

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orion, I bought the wheels from an RC website "greatnorthernhobbies.com" however they have since changed their name to "truenorthernhobbies.com" but I was just trying to access it and was having trouble with it! Hope you have better luck!

orion4455

Hello Dan! Friday, Oct. 24, 2014. Just wanted to say hello. I have great friends in Sacramento, Auburn, Colfax, and Truckee. Lived in Riverside/Palm Springs for 28 years. Your tams with offset hinges look great. I will be doing my doors soon, as its fall, and the weather is the nice "indian summer" time here in Fairfield, Iowa.
was wondering: before I get going on the wheel doors, perhaps I could speak with you. I always like to be educated when someone has already done the job, and in this case, done the job exceptionally well. The wheel wells look clean, neat, well organized, and just plain great! Great job Dan! I will email you when I start the work. Thanks again for being a great supporter for other guys who don't have your knowledge and skill. Best, Bob Gill, Fairfield, IA. (ORION4455).

orion4455

MSCHNEIDER2005: Thanks for providing all the great ideas, pictures, and knowledge about installation of the landing gear doors. Its a great help for people like myself who need the insight, ideas, and instruction before doing the work. GREAT HELP AND GREAT THANKS. bob g, Fairfield, ia. Orion4455