Rare Bear and a 49 Merc.

anm2 wrote:Roddie,  That Rare Bear looks awesome.  Did you draw the plans up yourself?  Andy

Thanks very much Andy. Yes, I found a 3-view of the Grumman Bearcat, studied it for proportions and started cutting/gluing wood together. I had never scaled a drawing before.. so I didn't really know how to do that... but I'd designed and built plenty of 1/2A profile planes over the years, so I had faith I could do it this way.

I always draw plans for a model I'm designing in pencil, as I go.. then if they need to be revised along the way, it's an easy task. The plan for this model needs a few more notations made, then I will ink it.

Here's the 3-view I worked from..



and here's the plan I drew for the model..

I need to bench run this engine some more.. while experimenting with fresh fuel.. (35% nitro is on my list of things to buy..) and adding head-gaskets. (only x1 installed currently)

To re-cap; this reedie has a dual-bypass/dual-boost ported SPI cylinder (Tee Dee clone) from Cox International.. with a standard-compression head. The rear-end has a "Killer-Bee" style backplate with a Mylar reed installed.



This is how I keep from losing small screws..



I had initial problems with fuel-draw from a custom-built hard-tank.. that seemed to have been solved by increasing the diameter of the fuel line to a size used for larger engines. My thought was; that if I decrease the resistance for fuel to flow.. it might overcome the reduced suction from using the high-performance backplate. (it would not stay running past an exhaust-prime without making this mod.) It simply uses a compression sleeve to hold the line securely on the small nipple of the NVA.



Before reinstallation on the airplane.. I want to bench-run the P/C in a couple of different engine configurations. I am curious to see how/if a venturi-throttle (Ace-style) will work. I will need to set up a "bee" (tank-back) engine to test this. I also have a Golden Bee that has a large (.082") factory-stock venturi.. that will be interesting to get some performance #'s on, when running this P/C. The parts on the "right" (both photos below) have the larger air-intake, as compared to the left.. which is a standard-smaller (.062") size.. as a Babe Bee has.




Bernie (Cox International) was curious as to whether the "Ace-style" venturi-throttle would work when using an SPI cylinder.. so I will perform a test and report my results using the standard air-intake. Just for "kicks".. I will also make (grind) a larger plunger-needle for the bigger air-intake, using 5/64" dia. (.078") music wire.. to see what kind of throttle-response I can get. If it works well.. then this style throttle could also be adapted for use on Black-Widows.. because they have the larger air intake.

My Ace clone arrived from Bernie today. Very nicely made. All aluminum, even the pin!

Phil

rsv1cox wrote:roddie, did the 57' Turnpike Cruiser have the slanted to the inside rear window that opened electrically?  

Nice "Rare Bear".  Doesn't Kim have a very similar model and isn't it available in kit form?  

Bob

Hi Bob, Yes.. it was called a "Breezeway" window.. and was also featured on later (60's) Monterey Park Lanes I believe. The Turnpike Cruiser also had vents along the front roof-line that could be opened and closed. My Grandfather had a 57 T/C sedan.. antique-white with fender-skirts and a "Continental-kit". It looked a lot like this..





Here's a shot of the front roof-line vents. My Grandfather used to brag about driving with 6 people in the car.. all smokers.. while raining.. and opening the vents while cracking the Breezeway-window a few inches.. and the smoke would just go right out the back without ever having a side-window open. I can still hear him uttering those words! He LOVED that car! I think it came with a 362 V8 Lincoln "Premier" engine.

The "inward-slanted" Breezeway-window was introduced by Mercury in 1963.. and continued through 1966? available on the Monterey, Montclair and Park-Lane models. This "inward-slant" probably didn't require as much trunk-space as the earlier Turnpike Cruiser's design did.

1963 Monterey-Breezeway


1964 Monterey-Breezeway


1965 Montclair-Breezeway (Gramps bought the "Marauder" (coupe) version of this car a few years later.. which he gave to us before buying a beautiful 1974 Cougar XR-7.. his last Mercury.)


1966 Monterey-Breezeway

Three headgaskets, high compression glow head, and a 5x4 fibreglass Cox Competition prop (shorten from 5 1/2 and thin with swept leading edge) and that will make a lot of thrust and take advantage of that cylinder and venturi. Those tiny flexy props just turn power into vibration. Another great prop for making thrust is the APC 4.75x5, they make a real difference at speed and seem to unload better than any other prop I've used on a 1/2A. I use a machinist friend to index and balance them. Though, I haven't actually flown all that many in the last few years they sure howl.
Give it a whirl Roddie, the Rare Bear looks fabulous.
Chris...

stuntflyr wrote:Three headgaskets, high compression glow head, and a 5x4 fibreglass Cox Competition prop (shorten from 5 1/2 and thin with swept leading edge) and that will make a lot of thrust and take advantage of that cylinder and venturi. Those tiny flexy props just turn power into vibration. Another great prop for making thrust is the APC 4.75x5, they make a real difference at speed and seem to unload better than any other prop I've used on a 1/2A. I use a machinist friend to index and balance them. Though, I haven't actually flown all that many in the last few years they sure howl.
Give it a whirl Roddie, the Rare Bear looks fabulous.
Chris...

Thanks very much Chris. Props are something I really need to pay more attention to. Up until joining CEF I was not an active flyer for many years.. and didn't have any mentors, especially when it came to 1/2A. I just flew for fun and would throw any 5 or 6 inch prop on my stock reedies without even balancing. Then came CEF.. and the speed contest. When I put together this engine.. I knew I had a different animal when I bench-ran it for the first time!

I had sourced three APC 4.75 x 4's from Tower Hobbies and all three wouldn't balance following my attempts on bushing the hubs to fit the Cox's 5-40 prop-screw size. I may have ruined all of them.. but before I make that assessment, I need to get a few of the spacers that Ken Cook designed expressly for this application. I'm told that a piece of fuel tubing used as a centering guide also works.. but I'd rather go with a precision-made bushing if possible.

I think you're correct about the Cox black prop causing vibration. I actually used a different one when I attempted to fly the airplane. It was a black Cox 5 x 4 that had a hub designed with "tabs" for a snap-on plastic spinner-cone. It originally came with my "Cosmic Wind" model. When attempting my flight for the contest, the spinner flew-off.. hit the pavement and cracked. Engine runs were erratic.. and the model was plagued with nose-overs when attempting to launch.. so I threw in the towel.

Until I can achieve consistency with this engine.. I won't attempt to put the Rare Bear in the air again. I was also very nervous with the 42' line length required for the 1st contest. I'd never flown with lines that long before. Jim Roselle has reduced the length to 35' for the current contest, which I feel a little more comfortable with. The "nose-over" issues were a compound-condition of rough pavement along with a slightly "tail-high" launch attitude caused by my pin-stooge. Upon release I could see the tail rise-up near level every time. Future flight attempts will be made from a smooth runway surface for sure.

I now have a high-compression head to try.. that I didn't have before. I'll start with 3 gaskets.. and give it a shot. As I mentioned though.. my fuel may have gone bad. I should get some fresh fuel before I can get an accurate baseline for engine tests.

Thanks again for the advice and compliments!

Fuel is pretty tolerant. If it is kept sealed, protected from light and extreme heat it lasts quite some time. Sealed prevents water form being absorbed. Light and heat break down nitro, which produces water. The alcohol is quite stable, as is castor when protected from oxygen.

Fresh fuel still won't hurt.

Phil

Nice Airplane

pkrankow wrote:Fuel is pretty tolerant.  If it is kept sealed, protected from light and extreme heat it lasts quite some time.  Sealed prevents water form being absorbed.  Light and heat break down nitro, which produces water.  The alcohol is quite stable, as is castor when protected from oxygen.

Fresh fuel still won't hurt.

Phil

I have always stored my fuel tightly-capped at room temp.. and never near sunlight. It's been sitting up on a shelf in my workshop which has a florescent shop-light (F40/25W x2 lamp fixture) on all the time. The fuel is about 6 feet away from and to the side of the fixture.. so it doesn't receive direct light from it. Is any florescent light exposure bad?

I had a case of insomnia around 3:00 a.m. so I started putting an engine together to hopefully run today. It's 50 degrees F. and climbing.. so it looks good.



Not your Grampa's Golden Bee.. This one has the larger venturi and the Tee Dee-clone SPI P/C with a high-comp. head. I installed a new venturi gasket, three head-gaskets, Copper/Beryllium (star) reed, new fuel pick-up and made a seal for the needle threads. I'm going to use my Kevlar gloves when cranking, because I have a gig tonight.. and need all  my fingers!

I also made a throttle needle for it.



Since the screen must be removed from the air-intake.. it's a good idea to provide a filter.



This filter media is Polyurethane used for air conditioners.. (also great for cushioning fuel tanks..)



I enlarged the hole in my guide/mount.. but the hole pattern for the bee-mount is sideways. I can still run the engine.. as long as the fuel pick-up faces down.

I put my fuel in a cardboard box... I don't know how bad fluorescent lighting is, of if it is any light.

http://www.rcuniverse.com/forum/rc-fuels-161/223049-nitromethane.html
http://rcvehicles.about.com/od/rcfuel/f/nitrostorage.htm

I also recommend reading some MSDS, although the ones I looked at did not say much about light and storage, since they generally assume steel drums.

Phil

pkrankow wrote:I put my fuel in a cardboard box...  I don't know how bad fluorescent lighting is, of if it is any light.

http://www.rcuniverse.com/forum/rc-fuels-161/223049-nitromethane.html
http://rcvehicles.about.com/od/rcfuel/f/nitrostorage.htm

I also recommend reading some MSDS, although the ones I looked at did not say much about light and storage, since they generally assume steel drums.

Phil

Thanks Phil, very interesting reading.

It was great to run an engine today! Nothing fabulous to report.. other than the fuel I used (Sig Champion "25") seems fine. The APC 4.75 x 4 turned what seemed like some SERIOUS rpm's.. but I had trouble keeping it on the engine. The first run was a screamer.. but by the time I leaned it out.. I was out of fuel before I could get my tach... and then backfires kept loosening it. I think this may be a good prop for this engine set-up. The prop-screw was short.. which didn't help matters. I switched to a Cox grey 6 x 3.. but couldn't hold a steady rpm.. so I called it a day. I didn't have too much time to do any more.