Here is the second letter from Cy Mao in Thailand, about his proposed lightweight Pietenpol.
Above, Roger White’s Pietenpol. It has a steel tube fuselage and an A-75. It is still flying in the hands of a new owner, I’m pretty sure it is more than 25 years old. I saw it in person at Brodhead many years ago. Notice it has Vee cabane struts, yielding a two piece wing and no center section. I believe this is far lighter than a center section, and it is also stronger. I do not know the finished weight of the plane, but it was visually a very good performer. Roger’s EAA # is 42, he built a number of planes.
Roger White stops by my tent at Oshkosh 2010. Note he is wearing a CIB from Korea. He is a first class American.
Response to the letter:
I believe you are correct, the VW isn’t radically lighter than a 65, but a UL-260 is a four stroke, light, and it makes very good thrust.
I would plan on 3/4″ spar slots in the ribs, I will see if I can get you some examples of classic planes with 3/4″ spars. I would still route them.
Manual is on the way tomorrow. I will see if I can find a picture of the 590 pound plane we weighed.
Thank you for kind words of King Rama IX and Thailand. Both are deserving of your kind praise.
I think I will try to build this and if over 550 Lbs I will only have to license as airplane, not ultralight but in the process I will discover the lightest Pietenpol practical to build. Or perhaps as you mention use Rotax but I like reliable 4 cycle and sounds nice too so could look at this UL-260. Also perhaps Volkswagen but I think not best RPM for Pietenpol like this and I think not so much lighter than A65.
I will follow your suggestions and am curious just which fittings and such you believe are overbuilt and can be aluminum not steel. But this is not yet critical to know. I will first build ribs.
Of course I’m also interested in your light landing gear you mentioned and the two piece wing you talked about.
I meant to ask if you think 1″ routed spar is lighter or the 3/4″ solid spar I read about. You mentioned a 3/4″ spar and still router it too. So I would think this for sure the lightest. How much to router I will ask later.
First I will build ribs 1/4 x 1/4 so I need to plan spar thickness to build ribs to fit this spar. I believe you suggest lightest possible is 3/4″ and then router too. Is this correct?
Also if I plan to build two piece wing as you mention what is the rib count for this version. I have only seen one and three piece wing views. Not sure how many ribs I will need if two piece wing.
Of course I will report my discoveries such as how much weight is saved by 1/4 x 1/4 capstrips and other things to change and finally of course if something breaks we will all know it is not enough.
You ask my address sir:
KGC – Unit 708 -Emerald Development Group
94/81 MOO 7, Vichitsongkarm Rd
Kathu, Kathu, Phuket, 83120
Note Delivery in Thailand sometimes slow or never shows up. Best if can track and return to yourself if necessary. Also I am happy to pay for book as well. When I see your video I already know I need one.
Thank you Kuhn William