Article: 3629 of rec.aviation.homebuilt Path: newshost.ncd.com!ncd.com!olivea!charnel.ecst.csuchico.edu!yeshua.marcam.com!zip.eecs.umich.edu!newsxfer.itd.umich.edu!gatech!newsfeed.pitt.edu!dsinc!netnews.upenn.edu!msuinfo!nscl.nscl.msu.edu!stetson From: stetson@nscl.nscl.msu.edu (JEFFRY STETSON) Newsgroups: rec.aviation.homebuilt Subject: BD5 Info (Long) Date: 25 May 1994 17:17 EST Organization: NSCL Michigan State University Lines: 102 Distribution: world Message-ID: <25MAY199417172266@nscl.nscl.msu.edu> NNTP-Posting-Host: cycdes.nscl.msu.edu News-Software: VAX/VMS VNEWS 1.41 OK, a brief (non-certified) history of the BD5 & present status ... It was, to my knowledge, the first kitplane, in the modern sense of the word, and came on the scene in the early 1970's. The designer, Jim Bede, had a good track record, (the BD-1 was certificated and produced as the "Yankee"; the BD4 was the only 4-seat homebuilt available at the time and had a good reputation). The BD5 was his version of the many different attempts at putting an airplane in every garage. His approach to getting good performance at low cost was to build the smallest, slickest airframe possible to be able to use a cheap lightweight 2 stroke engine. The performance of the prototype was very good and the price was right, so thousands sent in their money. The engine turned out to be the problem; the German company Hirth was given a contract to provide a reliable engine of the appropriate performance. What they produced broke (failed pistons) in flight. The reason for the failed pistons turned out to be (I think) crankshaft vibration, but without 'modern' tools for analysis of such problems, they went through several generations of piston designs. They were finally ready to deliver, four years late, but the original Bede aircraft company died a year before. (Hirth went bankrupt too, but was reformed, and now offers a line of air-cooled aircraft 2-stroke engines). There were about 3000 kits delivered, and these customers lost the money they had given toward the engine. Additionally, a certificated version was planned and several hundred customers lost their deposits. Hence a lot of ill will towards the design that has nothing to do with the airplane itself. Gradually, interest is coming back; there are more suitable engines than in 1973, and two 'full-service' companies are providing builder support that has been absent since the 1979 bankruptcy. IMHO, the key to the BD5 remains the engine. It was designed to perform well and safely with empty weights of about 450 lbs, which demands installed engine weights of 100 lbs or so. Here are some performance figures for what is IMHO a pretty good (but a bit overweight) example with an appropriate, modern engine: BD5-B, with 4 stroke air-cooled KFM 112 ======================================= Power 62.5 shp @ 3400 RPM Engine Weight 119 lbs Empty Weight 505 lbs Gross Weight 813 lbs Normal TO Weight 750 lbs Performance, 1500 MSL, 90 deg F: Stall (Clean) 90 mph Stall (Full Flaps) 67 mph Cruise (70% Power) 150 mph (An Austrian BD5 with a Rotax 582 (lighter) has been clocked at 200 mph.) Unfortunately, many BD5's (Honda-Powered) are flying very overweight, 600 lbs empty. These have flap down stall speeds in the 80's! Now combine the following factors: a) heavy = high stall b) auto engine (unreliable) c) high thrust line (power loss = pitch up) d) inexperienced pilot, maybe on a first test flight e) a 64 series airfoil that stalls at 10 deg AOA, but doesn't recover until 5 deg AOA f) minimal crush space ===> great disaster potential Now, the Microturbo TRS-18 & the BD5J has been a great combination! The 66 lb engine weight keeps the empty weights in the low 400's. The 220 to 300 lbs of thrust gives a top end of 280 mph and the jets have been tested to 410 mph. The only problem with them has been the $$$, say $120000 for a new engine, a 600 hour TBO, and 33 gph with a 36 gallon fuel supply. There were only about a half dozen made. All are highly prized airshow performers and would sell for $200000+. There *is* a lot of engine development underway with the goal of replacing the TRS-18 with a cheaper, better alternative, and, consequently another half-dozen BD5J airframes are under construction. The 75 lb, 95 hp Solar T-62 turboprop would also be a great engine for this plane. The best source of information is, at present, the BD5 Network Newsletter, published quarterly at $20/year (overseas $24). Back issues from Jan 92 are available (and recommended) for $2 each ($3 overseas). It's very well written & 'professionally' done. Write to: Rich Perkins The BD5 Network 34311 Bodkin Terrace Fremont, CA USA 94555 Phone: 510-797-2804 Both of these companies can supply all pieces, plans, and finished sub-assemblies for the BD5: BD-Micro Technologies 1260 Wade Rd. Siletz, OR 97380 Altruair 1405 N. Johnson Ave El Cajon, CA 92020 ==================== Jeffry Stetson "The cost of aviation remains constant - Comm ASEL everything!" Pvt SES, Glider Instrument Airplane stetson@35.8.32.128 Mooney M20E "Super 21"