Fokker DVII Replica

Hello all! I am calling on all replica builders and enthusiasts for help and support on my flying fokker DVII project. First let me tell you where I stand on the project and also tell you a little bit about myself. I am doing this to let you know that this is a legitimate request for information: I am a 32 year old pilot of 14 years who has begun to develop an interest in WW1 aircraft and it's pilots over the past few years. I have helped in the construction of a "Smith-Mini" Bi-plane so I have a little experience with wood and fabric. I am currently in possession of several authentic instruments: Tach, Altimeter, Greaser, Fuel hand pump, and other small items( Thanks Joe Gertler) I am also in possession of various drawings from the following people: Herb Kelley, Jim Keiger, and Dick Funke(Thanks to Mr. Oepdyke at WW1 Aero Magazine). Just like many builders I am looking for guidance and support to see this project through to fruition. I have hundreds of questions and am sure that there are answers to them all. Here are some examples: -Are people substituting 4130 steel tube instead of original 1020 steel? -Rib thickness for Fokker DVII appears to be 1.2mm(.047"). Is this available or have people used 1/16" thick Birch? -Too many questions to list about the tapered box spar. (WOW I am sure some hair has been lost over that component alone.) -people have used original Mercedes motors, Rangers and others. Has anyone considered others such as a V6 car engine? I hope that people who are in a similar situation or who have knowledge will contact me. All information will be greatly appreciated. Thanks and Blue Skies, Richard G Beinhauer RBeinhauer@aol.com Western Suburbs of Chicago

Richard,

Sounds like you have most all the current info on the D-7. Most people are using the 4130 steel in the States, some use the 1018-20 metric tubing but it is imported. There is a supplier here that has your metric plywood.
I'm building a Dr1 and have found most of what you'll need. Please drop me a e-mail and I'll try and answer any questions about who and where to get things. Also Dave Watts could help you with those engines he has a D-7 himself.

Mark

About the motors, I have often wondered if an *inline* six would work. The reason I ask, is that I own a '72 Chevrolet Blazer, and on the list of options available for it was an inline six. Mine has a V-8, but I have asked around and seen some in used parts houses. I would think that it would work, they apper very similar.

Butler

As long as the engine is modified for use at altitude and making sure that it works at angles other than horizontal, You can use any auto engine. The testing period for a auto engine equipped homebuilt is (in Canada) 40 hours of trouble free operation before certification as opposed to 20 hours for a certified aero engine, which as we know usually uses technology from the 50s

you need to join some of the sites at the Forum Links section of this page. Especially the Great War Aeroplane Asso. and the WW1 Repo Aero Forum. They can help with your questions.
Tally Ho,
Lt. Dwight Rudder, RFC

The problem with an auto engine, or a Ranger too for that matter, is the lack of cubic displacement as compared to period engines. Today's engines are high RPM, low torque as compared to low RPM, high torque back then. An auto engine will have to be geared if you want anything near similiar performance. If you've got the bucks (big ones) I've always wondered about the suitability of the Dynacam engine. It is a low RPM, high torque modern engine that looks like it might fit the bill admirably. Anyone examined this engine? I'd be interested in hearing your thoughts.

Your DVII won't fly like a original unless the prop is nearly identical and this means "big" by modern standards as well as slow turning in terms of RPM. (1450-1750 RPM). You can't expect a engine from later eras, ie 200 H.P Ranger, or any other powerplant to spin a prop similar to that of the VII. This obviously precludes any modern auto engines such as suggested in the previous responses. You need the prop of an original diameter and pitch and you need it turning at the torque and r.p.m. which was innate to the Mercedes or BMW of l917-18. This means, as an example,if a M-B, or more likely a BMW of 1918 put our appx. 200 H.P. at 1750 RPM, than the folowing is evident: If HP=Torque X RPM divided by 5250 then a 200 HP engine must put out 600 #s of Torque. I mean no offense to the prior respondents but the engines as suggested in respones wouldn't put out even half of the required torque. We don't know at exactly what rpm the max. torque was generated or exactly what the width of the torque band was, but you can, from these calculations, realize what was required of a power plant capable of twisting the "airscrew" that pulled the big ships of that era through the air. I looked the D-VII idea over years ago, went to visit Herb Kelley, secured his plans etc. I felt a big block Lincoln/Ford 460 was the best choice for a engine. It weighs about the same as a M-B (750 #s) and had the needed Torque at (as I best recall) 2200 RPM. A cam regrind and other mods. could be incorporated: Ie. Con. Rods of lesser length c. to c. will ordinarily give torque at significantly lower RPM, but this change of "rod-to-crank ratio" requires pistons with relocated wrist pin holes etc. You could reduce the prop o.d. minimally to stay within the prop tip speed limits. (There was a thread of a month or so ago that went into some of the arguments and dicta and/or arcane belief as re. limitation of tip speed as normally calculated). I, as you discern, was trying to stay with "direct drive". The intention was to eliminate any need to go into fabrication of any gear reduction device. You will need a supplementary front mounted housing however as it can be noted that the prop. is trying to pull the crankshaft out of the block at all times. Therefore anticipate here the need for an extension housing which will incorporate "thrust" bearing surfaces to absorb the tendency of the crank to shift forward. Moreover it will provide a location for a pair of bearings to support the prop. shaft. Cost considerations? You only have to recall that the Dave Blanton "Javelin A.C."" (Ford V-6) engines as developed several years ago for Experimental aircraft(and duster/sprayers)were priced around $20,000 so you can see that you could do a great deal of preliminary work yourself, pay some significant engineering and manufacturing costs and still be appreciably under the 20 K. Your replica would be worth 35-50 K. My final personal decision was to concentrate on the round engine versions of the WWI aircraft. I have several Continental radials ("220s) and know that you can get them ready for installation at about $10,000 or less.If all the V-8 rework seems complicated you could do a DVIII with a Continental and still feel as if you were truly historically participating in the Fokker experience: a feeling which you won't obtain in some lightweight and/or underpowered ersatz DVII. You should order the concordance from Leo O. which lists all the previously published articles. One article presents a description of a method by which you can build the tapered Fokker spar with far greater facility than would be expected. You do want to use 4130 which is incomparably stronger than other steels. Build an exact replica and be aware that there are Mercedes out there that can be obtained. You could fly it as a Ford, have a lot of fun and perhaps eventually sell to a collector/museum that has the original WWI Six in inventory. I know of at least one specific M-B in this category: Ie "not for sale but other options considered". Do it! VBR. Lee.

Lee:
Are you familiar with the Dynacam? My recollection is that it puts out about 220-250 hp at about 1900-2000 RPM, turning a very large diameter(as standard) composite prop. At about $20,000 it is very pricey, but it does have the advantage of being a certificated, thoroughly tested, reliable engine.

Hello gents: The specific article of interest on the Fokker spar-building device is in WWI Aero of Aug. '98. The "Rolling Planer" was built by Byron Peterson. 12215 N. 73 E Ave, Collinsville, Ok.74021. For Matt: I know of the engine you remark upon but while the cost is a deterrent there is also a problem of weight. You need that 750 #s or there will be a lot of redesign involving weight and balance considerations. I prefer to think in terms of the 460 as it is commonly available to all at a extremely low price. I would suggest getting any old engine running on a stand and first resolve the issues pertaining to control cabling,radiator mounts/engine mounts/exhaust fabrication/prop hub extension/propeller hub/propeller availability and other considerations which are the special concerns of mandatory interest should a a/c builder plan to utilise such a system. You can get the mods on the engine done later to maximize the approximation of the Mercedes/BMW RPM and Torque requirements. You could do a lot with increments of $500-1000 at a time. I feel it would be a contribution of great worth to the replica bulders community where certification is not an issue and where liability concerns probably dissuade much development of a suitable engine by commercial firms. The $20 K figures we've cited for available engines includes, no doubt, really significant charges associated with liability premiums. I think a competent individual (who knew what machine shops to avoid!) would find that for around $7500 he could get smoke out of the exhaust of a newly rebuilt ("torquer version") big block Ford which would be swinging a nice new "96 prop. with the required torque and at the desired RPM. Carry on! Regards! Lee.

Thanks for all the responses!!!

You all have given me great leads and good food for thought.

I can't believe I missed the article on the "Rolling Planner" in WW1 aero magazine. That is such a great and simple idea for the tappered box spar

Thanks again,

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