Question 25: "Hi Darrel, I plan on buying the Top Flite P-39 soon and I was wondering if I could build it with fixed gear first and then buy the retracts for it later(when I get enough money-I'm 14). Can I take off the fixed gear and attach the retracts with out doing much damage to the plane or is it best to just equip my next warbird with scale retracts? Thanks. Aaron"

Darrell: "Aaron, If you build the plane with fixed gear, try to make the mounts so that they will work with the retracts. Then you can make a plywood mount that you can bolt in place of the retract that will hold the wire gear. Another option is to build two wings. Use the parts from the kit to cut out a second set of wood parts and build one wing now and one when you get ready for a wing with retracts. Hope this give you a couple of idea's. Thanks, Darrell"

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Question 26: "I'll soon start construction on a Top Flite P-40. I was wondering what recommendations you would have as to what gear to use. I've seen the Robart 615's but I've decided that I want something that looks more like a strut and not like a piece of wire. "

Darrell: "Hello, This is a common problem with the P-40, Corsair, Skyraiders and Hellcats in this size range. There are no good pneumatic retracts for these planes. They are to small to put a good set of retracts in, and most manufactures won't design a good set because modelers are not willing to pay more than $150.00 for a set to fit this size plane. So we will have to live with what is
available until modelers are willing to pay a little more for a quality set. Another problem is that if a good set were designed, the wing would have to be modified to accept the new design and most modelers building these size planes do not want to deviate from the original plans. Sorry I could not be of more help. Darrell "

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Question 27: "Hi Darrell, I 'm doing research for building and documenting an F4U by Meister, 100" w/s. My question is, I am also considering using a retract door system for sale by another outfit, which includes doors, cylinders, etc. Does the door system need its own dedicated air supply or will Robart's big tank take care of doors and gear? Thanks for your help."

Darrell: "Karl, The size of the air supply you will need will depend on how big the cylinders are going to be on both the main gear and
the doors. It will also depend on how many times you want to cycle the gear between air tank fills. A large tank should be good for at least 2-3 cycles. You could use two tanks in a 100" corsair if you wanted more than that. Good luck with the project. Darrell"

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Question 28: "Hi Darrell, I've been following several posts from other modelers complaining about the retracts that are available on the market for the TOP FLITE P-40s, CORSIARs, or any other kits that use the currently available Rotating Retract Systems. It seems that if the airplane is involved in a "hard landing" the retracts will toe-in or bend causing an immediate nose over situation, thus damaging the airplane. Or if the retracts don't open to a full 100 degrees, the airplane noses over alot. And it seems that these complaints, though numerous, have not been addressed until now. As I understand it, your company, SIERRA PRECISION is involved in a trail production run of a retract system that will be more "Robust" than what's available, but some requirements will need to be met first.

What are the requirements that are to be met in order to get these retracts? How much will they cost? Will your retracts "fit" right in to an already built wing or will modification be required? Will I need a new Air System to actuate your retracts or can I use my existing Air System? Will these retracts open to a full 100 degrees? If I want to purchase these retracts from you, where can I send a payment?

I've heard nothing but PRAISES from other modelers who have used your retract systems on their GIANT Scale airplanes, so I can only imagine what you'll come up with for the smaller size warbirds. Thanks in advance!"

Darrell: "Hello, Here are a few answers to some of your questions. The cost is going to be $250.00. This will include the retracts with oleo struts, not just music wire. You will be able to use your existing air system. The retract might be a little larger than the currently available retracts but should only require slight wing modifications. The retracts will go the entire 100 degrees of retraction and have a positive lock in both the up and down positions. Are for the deposit, you may contact me at Sierra Giant Scale at 440-476-4885 and I will give you the instruction on where and how to make the deposit. Or you may use Pay Pal and send it to a special account at sierradeposit@aol.com. The Refundable deposit is $100.00 US. We will stand behind our gear as we do all of our other designs and only ship a reliable product. I hope this answers some of the important questions for you and others. Thanks, Darrell Tenny Sierra Giant Scale "

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Question 29: "Darrell, do you know of any machanical retracts that are suitable for the top flite gold edition fw-190 d-9 "

Darrell: "James, try Spring Air, they list that they have mechanical retracts for this size plane. Their web site list a few different designs. You might have to call and talk to someone to see if they have anything with the right angles, their site is pretty limited.
www.retracts.com Good Luck, Darrell Tenny "

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Question 30: "What is the best pneumatic retracts systems for H9 P51D .60 in pneumatic systems? "

Darrell: "Luis, I have seen several different gear used in the H9 P-51. Some people have use a small set or retracts from Robart while others have used Spring Air. I do not know exactly what model they use though. I would guess you need something to handle a 10 to 12 pound model. Robart's site is www.robart.com and Spring Air's site is www.retracts.com Hope they can help. Darrell"

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Question 31: "Hi Darrell, I am building a Bridi aero commander and would like to put air retracts on it. the more I shop for these the more confused I get. It requires rotating (90degrees) retracting mains. It will weigh approximately 14 to 15 lbs when completed. Are you familiar with the model and what gear would you recommend? Any help you can give me would be greatly appreciated.
Bob Deliere PS The model is the same as the Great Planes model of the Aero Commander."

Darrell: "Bob, If it's the one I have seen before, the plans show the old Goldberg Plastic nose gear unit for the nose. They also show the plastic mains with an added link the modeler had to install to make them rotate. These day's modelers would rather spend a few dollars more for ready to go gear. The nose unit can be bought from Sierra Giant Scale (www.sierraprecision.com) The mains could also be bought from them or maybe from spring air depending on how much you want to spend. Let me know how you make out. Darrell"

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Question 32: "Hi Darrel, I was wondering what some pros and cons were of having mechanical retracts over pneumatic retracts. I would like to purchase retracts for my TF P-39 that I am buying, but pneumatic ones are quite expensive. Thanks -- Aaron M. "

Darrell: "Hello Aaron, Good question. Most mechanical retracts work off of a 180 degree servo in the middle of the wing. They push and pull on a control rod to move the gear up and down. They do have a limit on the weight that they will handle though.
With a P-39, you will also need a servo for the nose retract as well. With 2 extra 180 degree servo's you are starting to get up to the weight of a set of pneumatic gear. They are also hard to hook up because you have to have the linkages just right for them to pull the gear all the way up. Pneumatic retracts are easier to hook up because they usually have the cylinder mounted within the frame. If you are looking at the total cost, just stick with wire non-retractable struts. The gear is the most important part of a plane if they are going to retract. A plane with retracts usually costs more, is heavier and looks better in the air with the gear up but really looks
bad when you land and they fail on you and your plane is sliding down the concrete runway on its cowl because you wanted cheaper retracts. I say pay now for good retract, or pay many times later for major repairs. Good luck"

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Question 33: "Darrell I'm in the planning stages of building a 40 sized J2M3 "Jack" (50" WS, 7Lb) and I need your advice. The scissors on the oleos face outward on this aircraft and every strut I've seen so far has rear facing ones. Do you know of a production set I could modify or am I going to have to roll my own? This is my first try at retracts, so I don't know all the brands out there. Thanks, John from Houston"

Darrell: "John, Only a few planes had the Scissors mounted on the side as you have indicated. The "Zero" was one. I don't know of many struts made with the scissors like you want because it is very rare to see. I would need some more info on what gear
you are going to use. I might be able to help you out. For a 7 lb. plane they can't be very big and you might be able to make something out of simple plastic to make them look scale. Let me know what you need and I will try to help. Good Luck, Darrell"

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Question 34: "Mr. Darrell, What is the typical set up for controlling the movement of gear doors so the wheel well is covered like the scale versions of the planes."

Darrell: "Matt, Their are several ways to install gear doors on model planes. The most important decision is in how much you want to spend to make them work like the full scale. Some planes just had its doors connected to the struts, while other where closed by hydraulic cylinders. With models, the easiest way is to attach the door to the struts with door collars. It all depends on how much you want it to work like it's full scale counterpart. Do a search on your particular plane on the Internet to find some photo's of how they should work. Also look around at your next scale event and see how other have made theirs work. Good Luck, Darrell"

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Question 35: "Hi Darrell I am building a Brian Taylor Hawker Hurricane and net to get some retracts, I have seen centurian and unitracts make some that suit, do you have an opinion on which would be better or do you have a better suggestion?
your thoughts would be much appreciated. Thanks Robert"

Darrell: "Hello, You only have a few other choices with retracts. Also try www.robart.com or www.sierraprecision.com. Both of them may also have something that will work for you. I have never used Unitracts myself and have fixed to many brand new sets of the centurian gear to recommend either of them. Good Luck, Darrell"

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Question 36: "Darrell, I'm building a Pica 1/6 scale P-40E. The weight specs say it should build to a maximum of 15 pounds. I can't seem to find anybody that makes a pneumatic retract system specifically for this kit or anybody that sells a 1/6 scale rotating retract, period. Robarts, Spring-Air, Century Jet, all have rotating retracts that "come close" to the weight specs on my kit, but I know warbirds build heavy and I don't want to "accordion" the landing gear on the first flight. How should I approach this problem? Should I just use 1/5 scale retracts? Corsair retracts? I need specific companies and models please. I've looked at one too many "Gear Matrixes" today and I'm quite frustrated. I'm also suffering from sticker shock on what these sets cost, so go easy on me. I'm even willing to make my own system if you could point me somewhere for some sort of mechanical drawings and piston suppliers. Thanks Darrell! Anything you can tell me would be greatly appreciated. Sincerely, Tim"

Darrell: "Tim, You should put the biggest retracts that will fit in your plane, but you need to make sure that they were designed to fit the Pica P-40. Every kit was designed to use some gear available at the time but they may or may not still be available. Other than Robart and Sierra Giant Scale, I could not recommend any other rotating retracts for your kit. They are the only manufactures with gear that are not sloppy from the start. As far as drawings and cylinders suppliers, I could spend hours on the subject but without having the plans, I could not describe in a letter how to tackle such a project. Good luck on you project. Darrell"

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Question 37: "hey darrell looking for some guidance on locating retracts for a giant scale he 111 that I am beginning. At 1/6 scale it will have a 148" wing and come in at close to 60 pounds. The gear resemble that of a mosquito and dc3. I could probably modify a set of those. Any thoughts?? deke tampa, florida"

Darrell: "Deke, I don't think that any of the standard DC3 gear out their would handle that much weight. You could have a set custom made if it is going to be a nice project. You won't want to chance a nice plane on a too small set of gear. Check with some of the manufacturers to see what they could do for you on a custom set. Good Luck. Darrell"

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Question 38: "I just purchased an already completed TF P-47 and the wheel covers where not attached. What is the best method for attaching the wheel covers to the struts? Thanks, Pat"

Darrell: "Pat, You can use some door collars that attach to the struts, then you can bolt the door to the collars. You will need 2 door collars per door. You can also attach the lower door to the lower fork. The P-47 had a 2 pc. door that slide over the upper door when the plane was on it's wheels. You can get the collars from www.sierraprecision.com. They have them in different sizes. Good Luck, Darrell"

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Question 39: "Darrell, I am building a 1/7 scale P51D (Svenson kit). I selected, bought and installed mechanical retracts in the wing attached to a Hitec HS75BB servo. The wheels are 3.5" size. Testing the setup I found out that the servo cannot handle the weight of the wheels. You will probably tell me to switch to air retracts, but that would mean I have to redesign the mountings. I am hoping that you would be able to tell me how to modify the retracts I have to a springload assisted version. Thanks, Peter"

Darrell: "Peter, If you are having problems only when retracting the wheels up, you can put a extention style spring either on the upper gear leg or on the pushrod from the servo to help pull up the gear. The down side to this is the servo has to have enough power to push the gear AND the spring in the opposite direction to put the gear leg down. All you can do is give the spring a test in
different locations. Hope this helps, Darrell"

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Question 40: "Hi Darrell, I am building a TP Spit and I am just starting to do the finish work and details. I am ready to mount the gear doors to the struts but I cant find any strut collars for a 3/8" strut. The gear are century jet, do you have any suggestions? "

Darrell: "Ian, Ask and you shall receive. Hope this is what you need. http://www.robart.com/RoboStruts/380%20Series.html Darrell"

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Question 41: "I’m looking for retracts for the Brian Taylor 1:8 scale 81” Mosquito PR.XVI. Suggestions? Thanks, Peter"

Darrell: "Peter, Unless you were to make them per the plans yourself, I do not know anyone that makes a stock set for the Brian Taylor Mosquito. You could use a standard 110 degree retract with a double strut and use a fake retraction strut. The weight of the plane will not be that much that it would not work. You might also see if any of the custom retract builders would be interested in doing a few sets. Good luck, Darrell"

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Question 42: "Hello Darrell , Great web site, I am building my first stand off scale model, my troubles are gear door attachment , I have laid up f/g doors and i am using oleo struts , so what is the best way to attach them to the struts? is there a book that deals with this in detail . any help would greatly appreciated thanks Richard Valdez 931-388-0752 p.s. the plane is a mk 9 spitfire 65" ws old Dave Platt kit"

Darrell: "Richard, You can get some standard door collars that clamp around the upper oleo and mount the gear doors to them. Sierra Giant Scale makes them in 1/2". 5/8", 3/4" and bigger. Measure your strut dia. and give them a call. You could also make some from hard wood and glue them to the struts are an alternative. Hope this helps, Darrell "

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Question 43: "Hi Darrell Could you please tell me the best way to bend the extremely strong wire that is supplied with Spring air kits as I am building a Skyshark FW190 D9 with their 85 Degree angled units but the wire is impossible, is it best to heat the wire or just bend it cold? if so how. Any help would be great, Regards from England."

Darrell: "Andrew, Nice to here from you. The best way to bend wire is to use a wire bending fixture if you have one, but most people don't. So, the next way is to hold one end in a vise and put a small steel tube over the other end to bend it at the right place. The tube will act as a lever and will keep the wire from bending where you don't want it too. If you need a certain radius, you can bend the wire around a round tube or dowl the appropriate size. Don't heat the wire unless it will just not bend any other way. The heat will remove any temper that may be in the wire already. Hope this helps. Darrell "

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Question 44: "Hi, Darrel. I'm wondering about strengthening up the mount screws on my P-38 nose gear by CAing nyrods into the drilled holes for the mount screws. After the CA dries, I'll thread the mount screws in. Would this help more with security, or would make any difference at all? Sincerely, SSG Robert"

Darrell: "Robert, You are not giving me much to go on as far as size on the P-38 model you have, but the best way to mount the screw is with a blind nut behind the mounting rail or plate. That way the tread can't pull out. If that is not possible, the method you described will be the next best solution. Good Luck, Darrell"

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Question 45: "Darrell, what retract do you recommend for a 1/4 scale Nosen P-51?" Chuck.

Darrell: "Chuck, I would recommend the unit made by Sierra Giant Scale (www.sierragiant.com), they have a nice unit that has it own cylinder and retracts like a real P-51. It has been used in many Nosen and Don Smith P-51's. Good Luck, Darrell"

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Question 46: "Darrell: I am building a Ziroli P 51 with Robart retracts. This is my first adventure with retractable gear. The gear itself seems to be managable, however, the doors are another matter. There is the main and the inner door. Is there some sorce of material for this job. Perhaps some pictures or drawings of somw workable solution. I see P 51s with and without inner doors and it would appear that this seems to be a problem for everyone. Any help would be appreciated. Curtis "

Darrell: "Curtis, They say a picture is worth a thousand words. Well here are a few photo's that should help you decide how you want to work the doors. http://216.157.131.210/Gallery/p51/images/Dcp03567.jpg Hope this helps. Darrell"

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Question 47: "Darrell: I have the plans for the Don Smith B-29 (169"). I'm not sure that Robart air retracts are the way to go. Your thoughts! John, Stockton, CA"

Darrell: "Don, Any of the brand name Retracts on the market would work in the Don Smith B-29.
The main question is reliability based on the weight of the plane. When most of the Robart gear were designed 5-15 years ago, they did not have the large motors we do today and the planes weighed a whole lot less. I have not seen the Robart gear for the Smith B-29, so I cannot answer as to what weight they will take. When you build a big plane like that, it is good to ask someone that has built and used a particular set of retracts as to their reliability. Sorry I could not help any more. Darrell"

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Question 48: "I’m currently busy With a Top Flite Sea Fury Gold Edition. I’ll be using a OS120FS motor with pump and I bought Century Jet Models Centurion Scale retracts. I’m busy constructing it and would like to know if there is any thing I must be aware of with these retracts. They do not open unless there is air available. Thanks for any help or info Regards Hennie"

Darrell: "Hennie The retracts you purchased have a double action air cylinder so you will need to use air to put the gear up and down. The only thing you will need to do with the gear is to keep an eye on all of the Pop Rivits and Set Screws to make sure they don't loosen up. Use some locktite on anything that has a thread because it Will loosen up after time. Enjoy your new plane. Darrell"

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