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Bruce Culver’s Fokker XXI project concept.

William Wynne

Friends,

Builder Bruce Culver wrote the note in blue below. He is kicking around a replica of a historic, but somewhat unknown, WWII fighter.  The letter caught my eye because it has some elements  I can comment on from personal experience. I included a three view and a spec. sheet from the original aircraft. These planes fought in one of the least understood facets of WWII, the ‘winter war’ , a 105 day savage conflict between the Finns and the Soviets. In spite of fantastic Soviet numerical superiority, the Finns fought them to a halt in minus 40 degree temps. Their national pride soared, but they learned the bitter lesson that they could count on no allied support beyond gestures. My comments on the project are in green and follow the letter-ww

“This is outstanding, William – thanks for letting us in on the secret that the ancient steam gauges I want to use will be pretty cheap because no one wants them anymore. I wonder what the backup system is for those glass cockpits if you have a major electrical failure – if the fancy panel loses power, you have NO instruments at all. And as you mentioned by implication, nowadays few instructors teach students to fly by the feel of the airplane. I KNEW I should have learned to fly in the ’60s….. Well, there is a lady who teaches around here in a decathlon,,,,,

I want to build a simple LSA replica fighter using the Loehle P-40 as a starting point and ending up with a Fokker D.XXI as the preferred design. I have tried three times to order the information pack from them and still don’t have it, but so much for customer service. Nonetheless I’d like a plane that will be fun to fly, safe and won’t break the bank at Monte Carlo. I also want to build the whole airplane and the engine, so I know what’s in both and can check better for problems, maintenance needs, etc. It will require a complete rework of the kit fuselage, but this gives me a chance to reinforce the cockpit area. One of their customers wrapped their P-40 prototype in a ball getting too slow on landing and stalled it in, but he almost walked away….. The pictures ain’t pretty. So, it’ll be wood, but good wood. The great thing about the Loehle P-40 and the Fokker D.XXI is I can leave most of the kit as it comes in the box and change only the cockpit and forward fuselage areas, so flying characteristics should be the same as the kit design.

My point is, Fokker D.XXIs didn’t have glass cockpits, so I can cheerfully go for the unwanted orphan steam gauges. And a Corvair engine, probably a basic model as it will power an LSA. And remember, there is always a place for knowledgable troglodytes…..”

General characteristics

Performance

Bruce, I like the basic idea and the XXI is a well proportioned aircraft that could be scaled to fit the task. At 28″, the Corvair is narrow enough to fit inside the radial cowl as long as the scale was bigger than 62% (5/8ths). At the Zenith open house dinner this year, Mike Loehle and his wife sat at the table with Myself, Becky Shipman, Dan Glaze and Dave Gardiea. Mike was there to support his covering and painting systems. In recent years, his kit company, just like all others, has felt the pinch of the economy. In years past, Loehle has provided 100s of builders very highly regarded kits, but the company operates in a very scaled back capacity from the peak years. If you sat across the table from him you would understand he still cares about builders, but has trouble justifying a full-time communication staff person. A good friend at out airport has a Loehle P-40 that is about 90% done. Let me say that this aircraft is way to lightly constructed for Corvair power. It is intended for two-stroke rotax engines only. Many more things would have to be beefed up than just the front fuselage.

As an alternative approach, think about the WAR replica aircraft. My next door neighbor built and flew a FW-190 powered by an 0-200. We also had one of these airframes fly on a Corvair in Europe a few years ago. They are 1/2 scale, and are too small except for medium and small pilots, and they don’t have the wing area for LSA. But, the wooden ‘dehavland box’ construction, fared in with non-load bearing foam and glass has merit. A number of one-off 5/8th scale fighters have been made this way. In St Augustine there is a 70% Hawker Hurricane that is probably made from this technique. For wing structure, you may wish to get a look at how KR-2s are made. 10 years ago a group of KR builders tested a new airfoil, and had coordinates for an 18% thick root section. This could be laminated into a very strong box spar. There are a number of low wing wood aircraft that could be studied for ideas like Jodel/Falconair single seaters. You can always look at a steel tube fuselage with wooden formers and fabric, it is possible to make a very shapely plane this way. Even if you don’t yet know welding, a challenging and unique aircraft like you are considering will require learning a number of skills. -ww

 

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