Here is an email exchange with Dave Cotton
Steve,
Thanks for your efforts with these events. It should be quite
interesting at the Nat's.
With respect to jet speed (my favorite subject, of course), I would like
to point out a couple of items. In the late 50's and early 60's Jerry
Thomas, Harry Latshaw and I were all running extended heads at
contests. Sometimes they worked, sometimes they were dogs. Also,
nearly everyone had the fuel tank at the front of the fuselage. These
tanks were carved out of the wood and sealed with either Ambroid glue or
epoxy resin. Our current fuels with propelene oxide will dissolve both
Ambroid glue and epoxy resins. Latshaw built one airplane with a metal
tank on the front and flew it at the KOI one year. It was so nose heavy
it only got one foot off the ground with full up. He trashed it when he
got back to Illinois. There might be some early jets with metal tanks
but I don't know of any. To use the current prop oxide fuel some
serious mods will be needed on vintage jets.
As a side note, if Ashley is interested in sport jet I can bring my
extra one to contests and if you are there she can try it out and see
what she thinks.
Cheers,
Dave Cotton
Hi Dave
I talked will Bill Pardue a lot about the Vintage Jet before we posted any of the rules. I asked a lot of question so I could get a feel of the Vintage Jet scene.
The forward tanks capacity will be a Issue with the use of 80/20 fuel. I would not be opposed if the modeler expanded the body to increase tank capacity or move the tank back some, as long as you maintain the outlines of the body, must keep those long noses. One of the plans not on the original list but after some research that would be legal is the Sidewinder. It wasn't published until February 1971, but Hoyt did fly the design at the 1961 Nat's, this would make it legal. This might make Vintage Jet a one plane event, I hope not. I've attached the article.
Bill did mention there was some experimentation with extended heads but with little success. So we decided to go with stock heads for now Under Engine in the rules, it is stated the "Modification are allowed provided that they were available and in use up to 1964"
We did not want fliers to show up with heads from current fast jet engine on old pipes. With everyone using the basic stock head, we level the playing field. Since no one published what modification in respect to an extended heads they made in 1965 or prior it will impossible to judge what is legal and what is not.
Engine:
Engines produced on and before 1964.
Modification are allowed provided that they were available and in use up to 1964.
No ABC conversions. No Schnuerled engines or tuned pipes.
Jet Engine modification that will be allowed is:
Opening of the ports, cowlings, back-up reed valves that we were running, modifying the reed retainer,
spray-bar & spark plug
Not Allowed
Intake extensions, pressure fuel systems
Ashley is really excited for this coming flying season. We were out last week and flew some combat planes in the snow. She did her first loop and I want her to learn how to fly combat that it will help her in her overall flying. She has been asking about sport jet and she would be excited to give it a try.
Dave let me know what you think about Vintage Jet. We want all the input we can get to make this a success.
Steve, Tom & Ashley
Steve,
Thanks for the refresher. The article tells me that the Hoyt sidewinder
did have a metal tank. I think I was at the '61 Nat's, but I'm not
sure. That was the year I transferred to Evreux AB, France and
marriage, family followed and I was pretty much out of the hobby when we
returned stateside. I think my last competition was the European
Championships at Genk, Belgium in 1963. The Hoyt sidewinder is probably
the only vintage jet of that era that had a metal tank. Billy Hughes
recently sent me some photos of Hoyt airplanes he got from a Hoyt
relative who had some questions about them. The fuselages looked as if
they had metal tanks (including the uprights) and now I'm sure they did.
I think I could make a metal tank for the Firedart. It would have to
extend further back into the fuselage and would be a soldering nightmare
to insure engine mount strength. But, maybe not. We need about 4
ounces of fuel, even with a "hopped up" engine. My sport jet tanks are
one 4" x 10" sheet of hobby tin. This is just a little over 4 ounces
and I get 16 laps on each flight at 142-143 mph. I could put one of
these tanks in a Firedart with a pear shaped fuselage instead of the
designed oval.
Another thing is monoline. This could be a problem. In those days it
was the Stanzel units and nothing else. I would not trust one of those
units in a current airplane. I still have a few, but I doubt many folks
do. Also, they do not meet present AMA safety criteria. The button is
to small. Our current torque units for jet use an external pushrod.
Everything was enclosed in the wing and the fuselage in "old" days.
Mods will, perhaps, be necessary.
Tank and monoline are the two major problems (in my opinion) to
overcome. I have a sidewinder sport jet and a new "radical" fast jet to
build and then I'll tackle this problem. I think we can make it work
with a little tweaking.
Just a little head scratching technical stuff now.
Hoyt's article says the rudder is necessary on the dolly to keep the
airplane (sidewinder) from coming in at you. Very true. For some
really strange reason, there has to be a scientific explanation, but I
don't know what it is.....the jet engine, when mounted and running,
wants to push down on the front mount. That is why upright jets have to
be flown with up control and are squirrelly sensitive when flying. The
sidewinder mounted engine pushes down on the front mount which means
it pushes inward and therefore the necessity for the rudder on takeoff
to counteract the reaction.
I think that's enough pratter for now. I'm planning to be at St. Louis
so I'll see you there. I'll chat with you later.
Cheers,
Dave