Model Concorde |
| T his radio controlled model Concorde was built in the early summer of 1999. It was a 50/50 project between Bob Blackmore and Bruce McKay. | |
 | |
|
| |
|
Bob is a well known flyer and builder/designer of model aircraft in the UK, and had been involved with a similar project some 20 years ago. It was decided to go for a 1/16th scale making the overall length 12ft 8 in. and using 2 Super Tigre 75's (running in reverse) as engines. Yes, the old fashioned prop driven method. We had already done some calculations and reckoned the flying weight would be about 27 pounds. this giving a very acceptable wing loading.
So we went to a local model/toy shop and bought a 72nd scale, plastic Airfix kit. These kits being well known as near enough to scale to make larger models. The first evening was spent crawling over this kit with a vernier and rule accurate to 1/2 a millimetre, taking down every dimension we could think of and scaling up to the required size. Bob set about modifying the design of the wing section to his thinking of what would fly well in a model, and he paid particular attention to the delta leading edge, anhederal and reflex. The reflex was particularly important as the release of air at the rear of the wing affects drag and determines the way the aircraft sits in level flight. | |
 |
 |
|
We had planned to construct using polystyrene foam and obeche veneer as the main materials for both strength and lightness, using smaller amounts of ply and epoxy/fibreglass as necessary. Balsa only features as nose and tail cones, leading and trailing edges and the control surfaces. The next step was to draw the templates to cut the foam. From this point on the building was just the usual hard graft of many evenings and weekends in my garage, burning some midnight oil in the process. We built the Concorde over a 6 week period with about 400 hours work in total to it's flying state. | |
 |
 |
|
The first flight was a real thriller, with a take off in about 130yds and a perfect climb-out to 100ft. Bob was at the controls and described it as a pussy cat to fly. On the third circuit he did a spectacular low pass at high speed and to our horror the rudder was seen to be fluttering violently - a problem that they also experienced with the real thing at the prototype stage. After a perfect and hurried landing the subsequent inspection showed that we had landed just in time as 3 of the 5 rudder hinges had broken due to the flutter. So it was back to the garage to repair and modify. We sought advice from modellers and even the retired assistant chief aero-dynamisist on the real Concorde's from back in the 1960's. It was remedied by a combination of mass balancing, squaring off the trailing edge and replacing the internal closed loop with a servo set in the tail as near as possible to the rudder. | |
 |
 |
|
More test flights proved we were on a learning curve with teething problems affecting the nose wheel retract and it's steering - it goes forward on Concorde. The engines (secondhand) didn't always seem to give the last ounce of thrust we were looking for, and a few times we experienced 1 cutting out that caused us to do a circuit and land as flight was marginal with only one running. Then came the real test, the 110yd long runway at Woodspring. We aborted take-off several times even though it was almost directly into the prevailing wind. So we changed props and did some static thrust tests, finding that 3 blades were giving us almost an extra pound. Using these take-off was between 70 and 80 yds. but the penalty appeared to be a reduced speed/acceleration performance once airborne. | |
 |
 |
|
Next came the landing at Woodspring and the wind had dwindled to nothing! I handed the transmitter back to Bob and ran to the end of the runway. Bob did a perfect approach and landed only 10 yds up the runway but with no brakes and engines cut it still hurtled along and, yes, I did have to catch and stop it at about 10mph, before the runway bridge that spans the stream. That became the normal practice for landing at Woodspring, although it will just about stop on the tarmac with a 7mph head wind. | |
 | |
|
This year we have been plagued with engine problems and running them backwards has not helped because the timing is slightly different than running forward. However the Super Tigre engines were second hand and we've now invested in 2 new OS 91FX. in theory, producing about 1 pound more each in static thrust. As I write this we are still running in these engines (even though we are told it's not necessary), and have yet again replaced the troublesome nosewheel and retract with a new and modified one. | |
 | |
Given some fairly settled winter weather we could well be taking the Concorde for flights, by car in its usual manner of being secured to a roof rack. (But the car is now a Ford Astra estate.) Yes, carried this way it does turn quite a few heads. It's a real shame the full size Concorde is no longer flying. | |
