Influential American aerobatics expert, Bob Palmer, was the honoured guest of Ku-Ring-Gai Model Flying Club in May of 2000. This report is by John Quigley, who took the opportunity to interview Bob extensively.
Ku-Ring-Gai is a very active C/L club in the Sydney area catering for all classes of Control line flying, although it must be said that the emphasis is on Stunt and Vintage Stunt within this group. I was looking forward to the privilege of talking to Bob and asking many questions, most of which he has answered before but not down under.
The day was fine with a breeze in the morning abating as the day progressed. There was a contest going on and there were some good flights, but most modellers were more interested in talking to and asking questions of Bob. My own efforts in the contest were mediocre as I was flying a Chief in windy weather, not a comfortable situation. The Chief is great to fly in calm weather but with a strong breeze it is a bit of a hand full.
I discussed the evolution of the Chief with Bob and it proved to be interesting. The Chief was designed in 1949 and the design was shared with Aldrich. I have built a "polywog" wing (sometimes described as a reflex wing section) and the virtues of this shape have been reported over the years. So let me report on this design from the horses mouth. While it is possible to get more ribs out of a sheet of balsa (as reported in the original magazine article) the wing shape was to aid the manufacture of the trailing edge and had nothing to do with aerodynamics or maximising the number of ribs out of a sheet of balsa. Bob did not want this shape for the following reason: he believed that a buyer would never again buy a kit of that design after trying to cover the wing. I feel that he was right on the button with his point of view
While there were flapped kits prior to the Chief these were not full span. An example of this layout is the Go Devil. The Veco Chief was the first production kit with full span flaps. Evolution showed that the flaps could have been larger but the full span flaps were revolutionary at the time. Later George Aldrich built many Chiefs with varying changes. Spinners, bubble canopies, Saftig or NACA0015 wing sections, half inch thick tails etc.
It seems that Bob and George are good friends and a variety of photos of them together have been published over the years. I went to the Ku-Ring-Gai event, with a Chief, that had been autographed by George Aldrich. I was naive in thinking that I may have the only model that survived from Georges Australian trip, some five years previously, and have a model with both signatures on a wing. This was not to be. Two other models have survived, both in much better condition than mine!
After the Chief with its wing there were a few followers with this wing shape. My most notable recollection is Bill Morley's Thunderbolt. Bob and I discussed landing techniques for the Chief. His method is much like the wheely method of a full size two wheeler aeroplane. Drive it down on the two wheels and use some down to hold it there and then some up to lower the tail. As we mostly fly over grass, my endeavours with this wing section are some what different in trying to get a gentle landing required by the judges. This sometimes results in a stall at about a foot if I do not get it just right. A wheel landing on a hard surface would be easier.
There have been many Thunderbird variations over the years. Upright and inverted engines, three wheels and the famous round cowl; Bobs prototypes and Veco kits. So which is the best Thunderbird? In Bob's opinion, his mark 2 version.
Bob tried to build his Thunderbirds to weigh between 38 and 43 oz. Many ideas were tried including the built up flap concept. An idea that was followed for many years by other designers. He abandoned the built up flap method fairly quickly as he believed that the flaps were twisting so he reverted to sheet flaps. He feels that two pieces of 1/16 sheet and a LE strip would give a light strong flap, though a good piece of quarter grain would be quite satisfactory.
A photo that Bob left behind is interesting: The 1955 US Nats winning model shown with the trophy has stall bars fitted to the wing LE for about 6 inches. This is a full size practice to make the wing root stall before the tip. Making the wing root stall first means the tips are still flying, and this provides a controlled entry into a spin. Or conversely, a pilot can feel the wing start to stall, and provided the pilot is not asleep can do something about the impending stall. What has this to do with models? Bob applied the stall bar full size concept to the Thunderbird to make it turn.
In Hungary at the 1960 World champs Bob was asked to do a closing demonstration flight. Many believed that Bob should have won that year using the inverted engine Thunderbird. Up to that point Bob had done more travel for demo flights than any other stunt modeller and was prepared to pass on his craft. It's a credit to Bob that he still does this today.
His flights in the UK with the classic round cowl Thunderbird in 1957 changed the style of stunt flying in the UK forever. No doubt the trip was invaluable to the UK. Travel to Australia in those days for most people was by ship.
The SAM35 Speaks documented the restoration of Bob's round cowled Thunderbird, its test flight and unfortunate crash. During the setup of this model much debate occurred as to what was a good engine setting. Well, Bob has advocated 5.2 second laps on 60ft lines with all other parameters irrelevant. The ageing model is being restored this time by Ian Russell in the UK. It was reported in SAM35 Speaks that the original Veco 35 was returned to Bob. He passed it on to George Aldrich for restoration and the engine has been returned to Ian Russell to be fitted to the restored round cowl Thunderbird which will eventually be on display in a UK museum.
Bob feels that the US are asking too much from the older models in Vintage stunt when the pilots are asked to do tangential horizontal eights. In Australia we fly the vintage eights as lazy eights, i.e. a straight section in the middle as was the style of the day.
Bob has fond memories of the Veco 35 for stunt. One must remember that he did work for Veco so there is some bias, but an organisation that has such a leader on their staff would take note of his point of view. The Veco was better finished than the Fox 35. Bob feels that the Veco 35 switched better than the Fox. While I have never used a Veco 35 the much later Veco/K&B 45 as used in the Skyscraper was a very good engine. There were a few of the Veco 45's used in R/C and they were just superb. My point of view is that today's so called Schnurle ported engines are not suitable for the lower RPM required for stunt as the passages are too large. I feel that a "Veco 45" design, especially the metallurgy in the piston cylinder department, with a satisfactory muffler and muffler attachment points, would be better than many of the current R/C engines being converted for C/L stunt. Tiger 46 / Veco 45 / Thunderbird / Nobler rivalry could be again fostered. The Merco 49, while a well engineered engine and very successful in R/C is considered a little on the heavy side for C/L stunt. All three are twin ball raced with the Veco 45 being a lapped piston.
Bob feels that today's models have lost direction and while the stunt schedule has not changed, the models are not fitting into the maneouvers description. As an observer I must agree. Either fly to the judges guide or re write the guide. Bearing in mind the above point of view Bob feels that the OS40FP is the most suitable current engine for stunt.
Other Palmer designs:
I asked what was the thought behind the Mars and Hi-Boy. Like the Pow-Wow both were driven by commercial requests from kit manufacturers. With the Mars he wanted to try a three wheel set up and to fit twin rudders to get them out of the fuse turbulence. The Hi-Boy also was driven by marketing and kit manufacturer's desires and neither were intended as serious stunt models. Neither were kitted so they were quickly published. I got the impression that he was not impressed with either the Mars or HI-Boy.
It is interesting to note that the Thunderbird design preceded the Pow-Wow. The Pow-Wow was again in response to manufacturers request for a 29 type model. The Pow-Wow is dated as 1954 while the Thunderbird first flew in 1953. This does not mean that all Thunderbird variants flown in age bonus stunt events should claim 1953 as their design date!
There are two Smoothies, the first was an upright engine and a rear high point wing section, resulting in a smooth flying model but difficult to turn. The second was an inverted engine and a different wing section. This resulted in a better stunting model.
Three wheeled Thunderbird:
Believe it or not, this is true! In the '50's there was a move to include an accurate landing in C/L stunt. So the theme of the "new rule" was for points to be awarded determined by the accuracy of the model stopping from a mark on the circle. The wording may be inaccurate but the concept is the important point. After some thought Bob built a three wheel Thunderbird with a brake on a wheel operated by down elevator. With some practice he could stop the model with the nose wheel on the mark, as required for maximum points. Bob again won contests. No other pilot could repeat the performance and the idea was soon dropped.
Bob's discussion on his tank proved to be quite a revelation. Not to put too fine a point on the subject ALL the drawings that have been published in the printed press are wrong! I will describe folklore and repeat Bob's description: three and a half inches long and a baffle three quarters of an inch from the back with the pipe stopping at the baffle. From that, most C/L followers will know what I am describing. What Bob described is interesting; the size does not matter and is changed to suit the engine. The baffle can be anywhere provided the feed line stops at the baffle. Usually he fitted the baffle three quarters of the way down the tank from the front! Filler pipes as per usual. Who is going to be first to try this tank?
The Day's Contest:
I think this was one of the most relaxed stunt days I have attended. It was the annual Ku-Ring-Gai Palmer/Aldrich classic stunt day. There were visitors from Queensland, NSW, Victoria, Australian Capital Territory and South Australia; a very good roll up. Many well finished models were entered, mostly Thunderbirds, one Skyscraper, (a model I like) some Noblers and Pow-Wows.
After the contest, Bob presented the trophies with enthusiasm to all the class winners then a huge photo session took place
At the end of the day Denis Percival prepared a model for Bob to fly, and did a shakedown flight. The wind abated and the sun was out; a wonderful afternoon and Bob took the handle. A nice smooth take off and a few wobbles to get the feel of the controls of a new model followed by inside loops some inverted flight, outside loops and some lazy eights. A nice landing after a full tank of fuel and loud applause from the gathered crowd. I hope I can still fly at 80 plus.
There was a constant barrage of plans being thrust in front of Bob for signing (including my Gee-String plan), and without hesitation every one was accommodated with personal attention. I have seen "stars" in other situations signing memorabilia in a most mechanical way, but not here.
I have had the opportunity to be with many influential modelers, but Bob is undoubtedly the best at analyzing the big picture.
I am indebted to the time taken by Bob to answer my many questions. I was 12 when the famous Aeromodeller stunt article appeared and it has been imprinted on my mind ever since. To actually sit down with the man himself and ask my simple questions was a wonderful experience. Bob is a quiet man who made himself available to all and answered all questions asked by me and all the other modellers who took the time to sit and talk. I feel Bob is not the person who would get up in front of an auditorium and discuss his exploits. During my time with him he answered all questions asked and in an informative way even though the same question was often asked several times. It was a pleasure and honour to meet him, an experience I will never forget. A thorough gentleman. Thank you Bob.
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