Frequently Asked Questions
I AM NO EXPERT!! ANY ANSWER IS JUST MY OPINION OR THE OPINION OF PERSONS I FORMED MY OPINION FROM.
What is the difference between the Pietenpol Air Camper and the Grega GN-1 Aircamper?
Basically the GN-1 is a modified Pietenpol that looks very similar to a Pietenpol when finished. However, anyone familiar with both designs can likely tell the difference.
Iím no expert on the GN-1 design because I am building a Pietenpol Air Camper, but I do have the plans for the GN-1 so I will try to list some of the differences.
There are more, but like I said, Iím not building a GN-1. One last thing Ö, note the difference in the name. A Pietenpol is called an Air Camper while the Grega GN-1 is an Aircamper. Note the Pietenpol is two words.
Aircraft grade spruce is expensive. What other wood can I use?
Good question. People have used all kinds of wood to build airplanes, but the most common alternative wood is Douglas Fir (DF). DF is slightly heavier yet slightly stronger than spruce too. It is more prone to splintering, a bit harder to work using hand tools, yet cheaper and more abundant than spruce. Steve Eldredge in Utah built his nice green and silver Air Camper using, I believe, select DF flooring. Many other flying Air Campers have been built using DF. Others have had luck in ordering DF from Internet and local wood suppliers. Before you decide to use an alternative wood, make sure you get a copy of and know the grading standards. This way you can order the grade of wood you want or select it from the pile locally. You should know these standards even if you are using AC grade spruce as well (Not all AC graded wood is acceptable). You can find some good information in a book entitled "Acceptable Methods, Techniques and Practices" (AC43.13-1A). This book lists the properties of the most common alternative woods as they compare to spruce. Also, the EAAís "Wood" book has a good article on grading wood, but this information can also be found in online sources. I remember one person saying he purchased 2"x12" DF boards because he could cut out spars from outer edges where the grain was more vertical. The best option, and if I would have known then what I know now, would be to use spruce for the 4 fuselage longerons, the complete tail group and the wing spars (If you can get some really good DF, Iíd use DF for the spars too). All the other pieces I would make out of DF. You can also try to find Western Red Cedar. I hear it works great for the wing ribs and the turtle deck stringers. Donít know if I would use it for spars.
Iím thinking about using Doug Fir for my Air Camper. If Doug Fir is stronger can I reduce the woodís cross sectional dimension?
Yes you could, but you need to know the engineering behind this to do it right. Also, once you go through all the calculations and effort, you are only going to save about 10 pounds. Personally, I think it would be easier to shave 10 pounds off the pilotsí weight than to try to save 10 pounds re-engineering the plane. Steve Eldredgeís Doug Fir Air Camper is lighter than some of the all spruce Air Campers, and as far as I know, he built his to the dimensions shown on the plans.
Aircraft grade plywood is expensive. What other wood can I use?
I have heard of marine plywood, hoop pine, birch, and some stuff called "Aquatek" and "Hydratek" being used. Make sure you get a copy of the aircraft grade standards for plywood. Also check the British standards as some plywood is graded to this standard. Most important of all, use good wood with no voids between the plies.
I like the tall wire wheels. Where can I buy them?
For information on building wheels, check out my Wire Wheel page. It sounds like itís not that hard to do. Check out Mike Cuyís and Larry Williamsí wheels to see just how nice a set of wheels you can build if you try. Ken Perkins makes and sells some really nice hubs if you donít have the tools to build them yourself ($180 for the pair in 2006). Also, you can try Aerodrome Airplanes for some ready-made wheels, but I donít know anything about their size or weight.
I donít want to use the Ford Model "A" engine. Can I use something else?
Yes, itís your plane. Use what ever engine you want.
Ok, thatís probably too short of an answer. You can use any engine you want. However, some engines are too light in weight, such as the VW and Rotax engines. Remember that most Air Campers, without the Ford engine, turn out to be tail heavy (aft CG) when the wing support struts are installed vertically. If you replace the Ford a lighter weight engine, you are bound to be tail heavy unless you compensate for it (See question below). The most common alternative engines on an Air Camper are the small, A-65 to 0-200 size, aircraft engines (probably the only plane where you can call an aircraft engine an alternative engine). The Corvair engine is another popular choice and one which Mr. Pietenpol designed. The Subaru engine as well as other auto conversions have been used successfully. Some even have a big old radial engine on the nose... man that looks good. (This is the engine I would use if I could afford one). By the way, you can purchase plans for the Corvair and Continental motor mounts from Andrew Pietenpol.
I built my Air Camper to the plans and the CG is too far back (i.e. the plane is tail heavy). What do I do now?
This is a typical problem with the Air Camper. The way to get your CG where you want it is to move the wing back. Yes, I said move the wing back. When Pietenpol designed the airplane, he made it so the wing is able to move forward and backwards. Unlike airplanes where the wing is built into the fuselage (Piper Cub style), the Air Camperís wing is held up by 4 center struts and 4 wing struts. The combination of the 8 struts (plus the wire bracing) keep the wing where you want it. Now that your plane is done, and knowing that the aft most CG should not be over 20-inches back from the leading edge, you can calculate where your wing needs to be. Most of the time it is 2-4 inches back (Using vertical center struts as a reference). This might mean you need to remake the struts going from the leading edge down to the top engine mount brackets (They are not on the plans, but everyone seems to use them).
You could also lengthen the engine mount, but be careful because Mr. Pietenpol cautioned against moving forward too far saying that the longer nose makes the airplane to not want to recover from a slip as easy. I always wondered what he means by "as easy".
Brian Kenney in Canada, has a A-65 Air Camper with its nose extended to keep the center struts vertical. Graham Hansen, said Mr. Pietenpol told him to extend his 6 inches. This has worked great for Graham. There is also the option of adding lead weight in the nose or installing a heavier engine. Sounds like justification for that radial engine to me.
I canít find seat belt installation details on the plans. Am I missing a page or something?
You canít find them because they arenít on the plans. This is one of the things you need to come up with on your own. I guess when you flew around in the 30ís you didnít need seat belts. It must have been fun flying in turbulence. I donít know if you noticed this, but there are no wind screens either. For some hints on how others have gone about adding seat belts, check out my Seat Belt archives.
Iím a big person will I fit?
Well that depends on how big you are. Vi Kapler (who used to work for Mr. Pietenpol) is a big guy 6"4 200lb and he flies a long fuselage Air Camper. However if you are on the smaller side, you will fit better. The best advice I can give you is to build a mock-up out of cheap wood, PVC pipe or cardboard and see if you fit. From what I hear, itís more of a space thing than the airplaneís ability to lift heavy pilots. You also need to watch the CG. Pietenpol's are notoriously tail heavly.
The Bleepedy Bleeping plans stink.
The plans are not as detailed as I would hope.
Well yes, they do leave some things to your own interpretation, but they are not that bad either. It seems that when you think you canít find something; say a dimension, if you look on one of the other pages it is there. However, the dimension may change depending on what page you are looking at, so be careful. I wish I could track down all the errors or supposed errors in the plans, but I have not been able to do this. The strange thing is that some people have a lot of problems with the plans, while others say they built to the plans and had no problems with them. I guess itís like the commercials say, "Your results may vary". I have a background building remote controlled airplanes, so in my opinion the plans are not all that bad. For instance, look at the horizontal stabilizer; it is made with ĺ" L.E., a 1" Main Spar and Ĺ" T.E. the tip is ĺ" where it mates to the LE, Main Spar and the TE. Right off the bat you can see these pieces are not going to fit together. So what you need to do is taper the front and back of the tip piece to match the LE and the TE and taper the Main Spar to join the tip. You only need to do this under the gusseted area. Make sure to use a smooth taper so you donít build in a stress point. Most of the time if you look at the plans and see how the parts are ultimately going to fit together you can usually solve most problems. Donít forget to ask others how they did it. Usually itís something easily solved.
What is the correct dimension for the spars 1" or ĺ"? The plans say 1", but the 3 piece wing plans say ĺ".
Some people use solid 1" spars as shown on the plans. Others use laminated 1" spars (5 pieces if 1"x1" laminated together) and others use solid or laminated ĺ" spars (Mr. Pietenpol did this on his last Air Camper). Itís up to your own personal preference on what to go with. Both seem to work fine. Iím opting for the 1" spar because I like the big beefy feeling to them. If you use the solid 1" spar do rout them. Yes, it makes a big mess, but it will lessen the weight. Iím not sure if you should rout a laminated 1" spar, but I donít think you're supposed to rout the ĺ" spars.
No one sells steel in gage thickness. They only sell it in decimal inches. How do I convert to decimal?
Here is the table I use. By the way, when ordering the tubing for the torque tube and bell crank bearings, make sure the OD matches the ID of the tubing it is supposed to fit into. I went straight off the table and had way too much space between the two pieces.
What kind of steel should I use for the metal fittings?
Well most people use 4130 steel. It costs more, but it is easier to find and is stronger. However, if you can find the 1020(25) steel, you can use that. The airplane was designed for this type of steel, so it should be strong enough.
Where is the best place to buy (stuff)?
First off, shipping will kill you. Buy as many parts as possible at one time. I shop at the local aircraft parts supplier for my bolts. I can stomach $10 every now and then instead of having to wait until I can order enough bolts to make the shipping cost acceptable. And Besides, I can buy the right size the first time instead of having to order two or three different lengths.
Get it from Dillsburg Aeroplane Works, 111 Sawmill Road , Dillsburg , PA 17019 . Telephone (717) 432-4589. I understand they have the largest selection of 4130 in the country. Rumor has it most, if not all, the homebuilt supply houses buy 4130 from them, so you might as well buy it from them directly without the added markup. They donít have a web site or a catalog, just a price list. If you need something metal, call them they probably will have it. I hear they also sell hoses, rivets, fittings, turnbuckles and such. Also, try Aircraft Spruce and Wicks, but check on prices from each before ordering.
Turnbuckles and other hardware
B&B Supply in Gardner Kansas, 913-884-5930.
I havenít found a good inexpensive source yet, so check prices at both Aircraft Spruce and Wicks. I have used wood from both.
I hear talk about a Long and Short fuselage. Whatís up with that?
There are actually three different fuselage lengths, letís call them the shortest, short and long. The shortest fuselage are the plans published in the Flying and Glider magazine. The short fuselage, also what is called the "Improved Air Camper", is the one shown on the 1933 drawings. The long fuselage is shown on a supplemental drawing, not dated (my drawing says it was revised in 1994, but I know the fuselage plans date before this).
Rumor has it the long fuselage was designed to be used with the Corvair engine (Air cooled engines). I donít know if this is true, but it does not seem to matter what fuselage you build and what engine you hang off that fuselage. Build the one you like and fit in. Mike Cuy, Steve Eldredge and others have the short fuselage with an A-65 (wings slanted back from vertical). Sky Gypsy (Built by Frank Pavliga and his son) was a long fuselage with a Ford engine. They have since removed the Ford and are now flying with an A-65 (and some lead in the nose I believe).
The long fuselage adds 2" in the first bay, 2" in the rear cockpit and adds 2-1/2" inches in the second to last bay and almost 3" in the last bay.
Do I need Jurry Struts?
The plans donít show them, but you need them. Even Mr. Pietenpol said you need them.
What are those struts which go from the wing to the engine mount?
Mr. Pietenpol used these struts to replace the X wire bracing in the front cockpit. This modification also makes it easier to get in the front cockpit. Mr. Pietenpol cautioned not to use too light of a material here. This also requires the modified upper engine mount shown on the supplemental plans.
Should I rout the wing spars?
Yes, always take advantage to save weight. A lighter airplane will climb better.
I want to make the wings fold.
Many have thought this, but as of yet I have not seen anyone accomplish it. The closest is the British quick connect aileron fittings so the wings come off more easily. But I understand this is still a pain. If you come up with a good way Iíd be interested in it too.
I canít find aircraft grade hard wire in the catalogs
As near as I can tell it does not exist anymore. I plan to use cable on my tail and wings. From what I have read; if you nick hard wire it can break more easily then stranded wire.
The design looks kind of flimsy, so I think I will beef up the ÖÖ..
No, donít do it!!! Itís plenty strong and all you will do is add weight. But ultimately itís up to you. If you really want to do it, first look at the Grega GN-1 plans to see if he already designed a beefed up component. It seems he did a lot of beefing up.
Can you recommend any books?
Get the four books by Tony Bingelis:
EAAís Wood book
I also really like "Aircraft Maintenance for the Airplane Mechanic" by Daniel J. Brimm, Jr. and H. Edward Boggess, Pitman Publishing Corporation, New York-Chicago, 1940 (I got mine off the internet for $15). It is a good source for 1940 building techniques.
To braze or not to braze that IS the question.
If you use the mild 1020(25) steel call out in the plans, brazing is fine. However, if you choose to substitute 4130 steel, you should weld. My understanding of this is when heated, the crystalline structure of 4130 opens up and allows the melted braze rod into the structure. Upon cooling the brazing metal contracts differently and causes, cracking of the 4130 steel and I think we can all agree this not a good thing.