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1959 Berkeley Impulse Single Channel Pylon Racer Build

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1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  GallopingGhostler on Wed Mar 05, 2014 12:48 pm

Latest project I'm working on is a 1959 Berkeley Impulse single channel pylon racer build. It has a 46" wingspan with 295 square inches of wing area. I'm tearing up a vintage kit, but it was an E-Bay buy for a song about 4 years ago. (Nowadays vintage suff is going for ridiculous prices on E-Bay.) Box was marred with water stains, kit looked like it had been stored in an attic for some time. Besides, if I attempted to sell it, would get about what it would cost to have someone laser cut parts.

It will be powered by a Thunder Tiger GP-07 modern Schneurle engine. I had thought about the Cox .074 Queen Bee, but that engine is just too long to fit in the engine compartment, would stich out at least 1.5" beyond the cheek cowls.

Instead of single channel it will be full house with a servo on each strip aileron, zero decalage on the wing, half the dihedral for better aileron action, servos mounted ala 3D style closest to the operating surfaces with shorter linkages. My build will violate vintage appearance points being brought up to date, but what the hay, they would have done the same in 1959 as well.

True to Berkeley style (or so I am told), the wood came with the traditional die crunching, inferior wood selection, and less than accurate die cutting, which makes for an excellent build. (Completing a Berkeley kit was an accomplishment, a rite in its own crude manner. It made many a man out of a modeler, LOL.)

Box art (how finished plane should appear):


Fuselage former die crunch:


Fuselage:


Wing:



Stabilizer:


So far, I'm having a blast with it!  lol! 
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Re: 1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  Cribbs74 on Wed Mar 05, 2014 3:14 pm

Nice George!

What does the kit call for power wise? .049?
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Re: 1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  GallopingGhostler on Wed Mar 05, 2014 11:26 pm

Cribbs74 wrote:Nice George! What does the kit call for power wise? .049?

Plans showed a Fox .09 Rocket engine. It is a side port engine like the Gilbert .074 and .11 Thunderheads, with venturi off the cylinder back. The piston forms the porting valve for intake control. It had the power of a .049 engine. Per Peter Chinn, around 0.11 HP at around 14,000 RPM. Props were 6x3, 6x4, and 7x3. These are the same props for the Thunder Tiger GP-07 that I am using, but it develops 0.19 HP at 18,000 RPM, favors the 6" props. From what I gather, the Cox .074 Queen Bee has roughly about the same power as the GP-07, too.

Gilbert .11 overtop plan:


Fox .09 Rocket engine (downloaded this picture from somewhere sometime back, if yours please let me know and I'll credit you):


Fox .09 Rocket had an integral tank at the back of the engine. The Berkeley plan shows no other engine. Although one is free to install whatever engine would work, which for this size of plane could be a .049 to a .10, nothing else is shown on the plans.

I will add a 3/16" thick ply spacer sanded to give about 2 degrees right thrust and radial mount the GP-07 to the engine bulkhead.
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Re: 1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  GallopingGhostler on Thu Mar 06, 2014 3:24 pm

Got the right wing built and stabilizer planked.



To keep this lightweight due to the lower power of the GP-07, am going to use Litespan / Coverite Coverlite heat shrink and Balsarite to stick it on.
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Re: 1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  Cribbs74 on Thu Mar 06, 2014 10:20 pm

Looking good George. I think the .07 will easily outpower the Fox .09 and the Gilbert.

Not to change the subject, but how is the S-1 coming along? I hope it will be done by July.

Ron
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Re: 1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  GallopingGhostler on Fri Mar 07, 2014 3:51 pm

Cribbs74 wrote:Looking good George. I think the .07 will easily outpower the Fox .09 and the Gilbert.

Thanks for the vote of confidence, Ron. The GP-07 fits in the engine compartment better than the other choices I have (Enya 09-III TV, A.C. Gilbert .11 Thunderhead, Fuji 099S-II RC, Cox 047 Queen Bee, etc.).

Not to change the subject, but how is the S-1 coming along? I hope it will be done by July. Ron
S-1 is completed except for fuel proof clear coating. I'm waiting for a break in the weather (warmer with not wind) so I can spray it. I do want to fly it before March is out.
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Re: 1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  Cribbs74 on Fri Mar 07, 2014 4:47 pm

I like the idea of the Enya. Power is really good, but it's a bit heavy. Although with that big tail it may work quite well.

Here is a engine test of the Enya .09 III

http://sceptreflight.net/Model%20Engine%20Tests/Enya%2009-III%20CL%20&%2009-III%20RC.html
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Re: 1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  GallopingGhostler on Fri Mar 07, 2014 8:47 pm

Cribbs74 wrote:I like the idea of the Enya. Power is really good, but it's a bit heavy. Although with that big tail it may work quite well. Here is a engine test of the Enya .09 III http://sceptreflight.net/Model%20Engine%20Tests/Enya%2009-III%20CL%20&%2009-III%20RC.html

I've seen that test report, Ron. I am totally impressed on how well the Enya .09 flies, it's power is just as good as the .09 and .10 sport Schneurles. It likes the lower mass wood props. With a 7x6 Top Flite wood, it really moves out, adds spirit to any mild .049 plane. Torque is in the lower RPM band, around 12,000, so there is no advantage to running smaller props than 7x4. Its cousin, the .09-IV is a tad more powerful, but the III holds it's own.

Another plane I've got with the same proportions is the 1962 Airco Aero Star.



It is an odd swept high wing cain model with same wing area and tail moment. I may build that one as rudder and engine control. It would be a candidate for the slightly hotter Enya .15-III TV that I have.
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Re: 1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  Cribbs74 on Fri Mar 07, 2014 10:40 pm

I was impressed with the amount of nitro it can handle. Parts are probably scarce so I would go over 15-20%

Ron
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Re: 1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  GallopingGhostler on Sat Mar 08, 2014 7:23 am

I've been using 22% nitro fuel with it, and it runs just fine with a legacy Tatone .09-.19 Peace Pipe muffler. (Those Peace Pipes do fine as long as one stays with the smallest or less than that stated sizes. Am using the .29-.40 Peace Pipe on an Enya .19-VI TV.) I think one could get by on even 5% nitro with these Enyas. I like them because they are powerful, will spin larger or greater pitched props easily.

I found that the Enya .15-III TV with throttle wired open with 8x6 prop put out as much thrust as my OS Max .15FP-S with 8x4 prop. They have a lot of torque in the lower than Schneurle RPM band.

Regarding parts, Enya is still in business. Not sure but I think the current .09-IV version sleeve and piston might work in the III. The muffler works. The .09-III is odd in that the exhaust is on the left side of the engine. It's one reason why I installed one upside down in my OK Models Pilot Cessna 177 semi-scale.
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Re: 1959 Berkeley Impulse Single Channel Pylon Racer Build

Post  GallopingGhostler on Sun Mar 22, 2015 9:05 am

A couple days ago I received a gift from Dane Martin, CL flier and friend, a 1966 OS Max 10R/C cross scavenge engine with 702 muffler. This muffler is as rare as hen's teeth.


I was lacking a suitable powerplant for this 1959 Berkeley Impulse single channel pylon racer / trainer build. Fuselage sides engine cheek cowls were too closely spaced to fit the A.C. Gilbert 11 Thunderhead side port, which would be in the same class as the 1950's Fox 09 Rocket side port shown on the plans, ditto for using an Enya 09-III TV. Didn't have a needle set screw for the Thunder Tiger GP-07 to extend it beyond the cheek cowl. Cox 074 Queen Bee stuck out almost 2 inches beyond due to engine's extra length. My other OS Max 10R/C's have only the variable exhaust restrictor baffle ganged to the carb, which cheek cowl interfered with. This gift engine fits perfectly. On a 7x5 wood prop ought to haul this 46 inch span model with reasonable authority. I am making a few other mods to it to make it fly better on full house.


This engine looks like it was made for it. With a very ample muffler chamber volume, should have little loss in power. IMO so well engineered are OS mufflers that Peter Chinn mentioned that the earlier muffler, which is slightly smaller in volume basically caused a negligible decrease in power.
I'm stoked! St.Pats Beers Thumbs Up Cool
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