A Special Note to All BD-5 Builders

This letter is intended to give all of our BD-5 customers a clear and accurate status with recommendations on the various options available for the BD-5. We have spent two years of hard, concentrated work in testing and evaluating every possible variation that came to our attention for the BD-5. Rather than establish a single configuration of the BD-5, we felt that certain options could be incorporated. Now that evaluation of all these options has been completed we'd like to share with you the results and our recommendations.

A and B Wings

We have flown the BD-5 with both sets of wings and have completed all stability tests except spins which will be done shortly. The overall handling and stability of both wings is good. The A wings, however, do have a faster rate of roll capability and higher wing loading which results in higher takeoff and landing speeds. The B wings, on the other hand, possess a slower, but still excellent, rate of roll and very good gliding and low speed handling qualities.

Takeoff and landing performances are appreciably better for the B model wings. Since the BD-5 is a single place aircraft we recommend that everyone obtain a set of B wings and that first flights be conducted with the B wings. We encourage this particularly for relatively low time pilots. After becoming thoroughly familiar with the BD-5 a change to the A wings is a simple matter. Although we see no adverse characteristics of the A wing for even a first flight operation, it is apparent that the low landing speed and the excellent gliding characteristics of the B would make early flights with the BD-5 on the safer side with the B wings.

Engine Sizes

Of the three engines available for the BD-5, we recommend the largest engine of 720cc displacement as the most ideal engine. It not only produces the maximum power for the best overall performance, but it is a new engine specifically designed for us and incorporates the latest technical features as a result of our extensive test programs.

This 720cc engine has an advanced new cylinder, cylinder hear and piston design compatible with dual ignition to permit aircraft operation at high continuous horsepower. This engine is so well designed that it is lighter than the 650cc engine. The added horsepower provides higher cruising speeds and as an added benefit shortens the takeoff distances and improves the rate of climb. With over a 25% increase in power over the 650cc engine the performance results are obvious.

Some of our customers expressed concern on fuel consumption but it must be remembered that the largest engine can be throttled back to the same cruising power of the smaller engines with corresponding fuel consumption the same as with a smaller engine. The resale value of the BD-5 with the larger engine would be considerably higher maintaining the investment of the larger engine. Only the 720cc engine is scheduled for type certification as the certified standard aircraft engine. Because of these benefits we strongly recommend the larger 720cc engines as the best choice.

The next best engine would be the 650cc with dual ignition. This engine has been used in all our current flight test evaluations and demonstrations. We find it to be totally acceptable as an engine for a BD-5. This basic engine has been used on snowmobiles and other ground transportation vehicles. We are satisfied with the engine and will continue to offer it for both our BD-5 and new BD-6 aircraft.

The third engine that could be installed on the BD-5 is the 440cc engine. While this engine is lighter than the other two available it provides less horsepower. Although this is the least expensive of the three engines we feel that our customers will be much happier with one of the larger engines. It is only available in single ignition and is basically a standard snowmobile engine. There seems to be no problems with reliability of the engine. However, many of the features incorporated in the 720cc engine will not be available on this model. We will delivery the 440cc engine if a customer so desires. However, we may be discontinuing it in the near future.

Dual Ignition

We highly recommend the use of dial ignition on the BD-5 engines. We do this simply because the weight and cost of the added ignition system is small and the dual ignition provides that additional safety factor. Our test and demonstration experience has been excellent on all the ignition systems. However, with a dual ignition system, engine shutdown due to ignition problems becomes remote. Aircraft electrical power is generated in the ignition system, therefore, with a dual ignition system, an additional source of power is available as a standby system.

NOTE: If you ordered your aircraft prior to October 15, 1972 (when the base price was below $2,600), cost of the dual ignition system is $72.00 to you. However, when the base price was raised to $2,600, part of this increase was to compensate for the cost of the dual ignition, to those customers who ordered after October 15, 1973 will receive dual ignition with either of the two larger engines at no additional cost.

Because of the overwhelming customer interest in the dual ignition system, all 650cc and 720cc engines in our initial production run from Hirth will be fitted with dual ignition. Should you desire one of these larger engines without dual ignition, it will only be available on a "special production run" basis after our dual ignition commitments have been fulfilled.

Please remember that in no case will 40 HP engines be supplied with dual ignition.

Variable Speed Drive

We do not recommend the variable speed drive and are discontinuing it from our optional equipment. We did conduct many tests, air and ground, on this unit and found it to be operational. However, we were unable to guarantee a reasonably long belt life. It was possible with the variable drive that the belt life would be more than adequate but the only method of confirming this was to have many of these units operate in aircraft over a long period of time. We did not want our BD-5 customers to be part of this experimenting. After extensive testing, we have settled on a fixed drive system as the operational unit. We can guarantee the belt and drive system to over 1,000 hours of operation. For those of you who have already paid for the variable speed drive, the $90 will be credited to your account automatically, and you can apply it to other equipment or request a refund.

Electrical System

We do recommend the use of the electrical system on the BD-5. It provides push-button starting for ease of operations. It does permit the owner to use electrical instruments and radio equipment. This option can be purchased later and retrofitted on the aircraft. However, it is easier to install the battery and do the necessary electrical work during construction. This option is not mandatory. It is a good feature and adds convenience and utility to your aircraft.


Also, many of you early customers have been asking about the interest program. Enclosed is a complete outline of who is eligible, and how the interest will be paid. As you can see, there is no way we can tell you how much your interest will amount to until we have shipped all of your parts.

Therefore any change to your order which requires additional payment must be accompanied by a check or money order for that amount, or we will not consider it a firm order.

If after considering all of the above information you are satisfied with your order as it currently stands, no reply is necessary.

If, on the other hand, you wish to change your order (i.e. add a larger engine or dual ignition, etc.) please notify us in writing and remit the correct amount of money on or before October 31, 1973.

Bede Aircraft, Inc.

Last Update: 5/17/97
Web Author: Juan Jiménez
Copyright © 1997 by Juan Jiménez - ALL RIGHTS RESERVED