Mini-IMP Aircraft Company

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Building Time

Most potential builders are interested in “how long” it will take them to complete the construction of any homebuilt design they are contemplating. This is very difficult to answer since we have no way of knowing the degree of your skills, experience, equipment, facility, etc.  It is impossible for anyone to give you an exact estimate of how long it will take you to put a Mini-IMP together.  It depends entirely on how fast you work, how long you take to talk things over with the multitude of friends that are bound to drop in to see your project, and how long it takes you to get all of the parts and materials together.  If you are handy with tools and you have good facilities and working space, you should be able to build your Mini-Imp in approximately 1500-2000 hours.  If you are not handy with tools, find difficulty in reading drawings, and find it impossible to follow instructions, it will take you longer. This compares with an estimated 10,000 hours to build a Falco or 1,500 hours to assemble the kit of a typical fixed-wing, fixed-gear aircraft. The longest documented amount of time taken was 5000 hours by Seńor Bernardo de Sousa Dantas of Sao Paulo, Brazil.  He made many changes and also performed his own conversion on the plentiful VW engine.  You will probably take much less time. When people quote so many years to build an aircraft, they mean that they chose to spread the number of hours required over that many years, for whatever reason. If you have a limited amount of time available, consider subscribing to the newsletter, to see if there are good projects for sale that you can complete.  However, we want to give you every reason to succeed, and the Mini IMP Aircraft Company is available to give you advice, help you find parts, and assist you.  It must be remembered that since there are dozens of people wanting more information, it helps to make your letters or phone calls worthwhile.  Please don’t ask questions that are already answered in the drawings or instructions, and enlist the help of experienced friends wherever possible.  If you do have to write, be sure to send a self-addressed stamped envelope along with your specific questions listed on a separate sheet.  If you call on the phone, have your questions in mind.  The best method however, is to use the Mini-IMP Builders Email discussion group to send your inquiry to all participating builders.  See the information in the Email section of this information package.

Building the Mini-IMP

Probably the second most repeated question we get concerning the Mini-IMP has to do with “how hard is it to build?” 

Molt tried to do everything possible from a design standpoint to make it as easy to build as something like this can be.  He tried to incorporate detail drawings of every little piece.  He also came up with “assembly” drawings of how the pieces go together.  Molt detailed everything and dimensioned everything so that there can be little question as to how the individual parts are made.  It should be recognized that since each builder is going to be making only a single example of the Mini-IMP he is going to have to develop his own assembly methods, provide the necessary alignment etc., so that things all fit once he gets them made.  This obviously entails the need to drill and fit many things together upon assembly.  In a factory, parts are made on master jigs so that all of the holes will align when assemblies are put together.  With a “homebuilt” we jokingly say that our “master jig” amounts to throwing the parts in the air and nailing them together before they hit the ground.  Seriously, you have to do a lot of planning to be sure that you are going to be able to make things fit and assemble together as indicated on the drawings.  This is probably the most difficult part of building any homebuilt airplane.  It is very easy to spoil a part just because you didn’t anticipate how it was going to be fit together with some other part.  However, you should recognize that you do not build the whole airplane AT ONE TIME.  It is built ONE PIECE AT A TIME, and there are no parts in the Mini-IMP that are hard to build.  Builders should build the wings first.  This is the most time consuming part of the Mini-IMP to construct. 

The designer had wide experience with the “Coot” light amphibian homebuilt and worked with dozens of “first builders” who had never built anything like an airplane before.  This experience enabled him to design the Mini-IMP with even more consideration for the total amateur builder.  The full size patterns enable you to quickly lay out parts which might otherwise be difficult to make.  All bends of the sheet metal are straight.  A detailed “shearing guide” permits you to take your sheet metal to a local sheet metal house and have it all sheared at one time.  From there on it is more a matter of cutting off little pieces, bending them sometimes and drilling holes and bolting or riveting things together.  Some small parts are made by merely cutting them out of the proper material with a band saw, and then sanding the edges smooth on your belt sander, drilling some holes, and the parts are ready to be assembled.  We have lined up suppliers who have complete lists of things like the “aircraft hardware”.  These are things like the bolts, nuts, washers, pulleys, cable, fittings, etc. which are “aircraft grade parts”.  There are many aircraft supply houses in the country and you can find their ads in “Sport Aviation” which is the monthly magazine for the Experimental Aircraft Association (EAA).  If you don’t belong to the EAA, we suggest you join immediately.

There are only a couple of welded assemblies in the Mini-IMP.   These include the engine mount and main gear pivots which are available pre-made.  These parts are all detailed in the drawings.  There are some things which take very costly tooling to build.  The shaft system is particularly critical, and we do not recommend that you attempt to build this yourself or have it built by anyone other than an experienced machinist.  Materials and components of the shaft system are obviously critical.  The instructions that come with the drawings cover the installation, alignment, balance, and maintenance of the shaft system in detail so that you can perform those operations yourself.  Things like wheel alignment, brake installation, control adjustment, etc. are covered in the instructions.  We feel that if you have even modest mechanical talent you should have no difficulty building a Mini-IMP even if you have not tried something like this before.  We might suggest that if you can find a nearby chapter of the EAA that you join them since such groups usually have several experienced homebuilders in their membership and these people are usually only too happy to assist you with anything that might be giving you problems.

The photo set, which is included in the drawing set can be a great aid to a “first time builder”, particularly if you are not experienced in reading drawings although our drawings are very detailed.  Further, Mini IMP Aircraft Company is available on the phone (your nickel please) to discuss any problems, direct you to suppliers, etc.  As Molt liked to say it “WE WANT TO GIVE YOU EVERY REASON TO SUCCEED”.

General Construction

The years of experience that the designer of the Mini-IMP acquired with homebuilders have shown that the ideal homebuilt design should require no welding.  It should require a minimum of tools, and it should not require many costly machined parts.  While it is impossible to design an aircraft with out some of this complication, the Mini-IMP has been designed to keep these requirements to a bare minimum. We are investigating the possibility of offering a complete “kit” of materials.  At this time only those items indicated in this information package are available.  However, we do plan to further investigate the possibility of making arrangements with other outside suppliers to have kits of such items as aircraft hardware and all aluminum available for those builders that may find it difficult to locate suitable parts and materials easily.

The Mini-IMP has been designed to be built with a bare minimum of special tools.  Thus, a drill press with variable speed, a metal-cutting band saw with variable speed, and a bench sanding belt are the only power tools necessary other than usual hand tools.  A variable speed 3/8” chuck electric hand drill (or equivalent) is necessary.  A propane torch for brass brazing is desirable, although this work can be easily done by some job shop.  A variety of high speed drills are needed, and these are listed in the drawings.  Good quality sheet metal snips are required.  A hand riveter is required, and if the aircraft is to be flush riveted, a hand dimpling adapter for the riveter is needed.  There are a few long sheet metal members that must be sheared.  These can be done by a job shop, or can be hand done and the edges reworked and filed to get the desired smooth edges.  There are some members which must be bent, but these can be bent over the edge of suitable planks.  Drawings on how to do this are included in the drawing set.  Other than these special considerations, the builder needs a good work bench, a heavy vice, and the usual hand tools found in any hardware store.  The Mini-IMP can be built in a single car garage.  Wooden jigs to support the structure during construction can be made from 1 X 4 or 2 X 4 material available at any lumber yard.  The drawing set lists all tools and hardware needed for construction.  Outside contractors are being lined up to supply many of the hard to build assemblies.  Although none of these are really complicated or expensive, it is recognized that some builders would rather buy as much as possible and still stay legal within the FAA requirement that they do 51% of the work.  This requirement is easily met when building the Mini-IMP since there just isn’t too much that is needed other than putting it together.  The basic structural material for the Mini-IMP is 2024-T3 aluminum sheet.  There is no heat treating of the aluminum required.  The only heat treated parts in the aircraft are the main landing gear legs and the nosewheel leg.  These components are available.

Although there is some fiberglass component trimming necessary in the construction of the Mini-IMP there is absolutely no fiberglass lay-up or fabrication necessary, with none of the fumes, mess, and other problems such as skin allergies (necessitating work gloves, etc.).


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