CEF speed contest Design Discussions

Temporary cowling and removable landing gear in place:


Jim

Nice, NICE Jim! I love utilizing hardwoods into my aircraft. Handsome engine plate! Mine will be hiding in the cowl...

Looks really nice Jim.

Roddie-I might still build a bipe to try. Just need to find one that looks right. The racing bipes have short fuses.

Ron-That's a great idea. I'll look to see if there's a local contest that I can run that Gee Bee in.

Duke... I feel your pain... I've struggled with the F8F-2... but at least it's closer to a "lawn dart" now... (to quote Jim) I had sized the engine plate for a vertical "tanked" engine... luckily; a horseshoe back-plate will mount horizontally... which gave me the option... and a huge c/g trim.

The "Pitts" bipe is awesome!! I'd re-think it...

A little work... and weighing-in... I won't be running that wood 6 x 4... but I liked the way it looked for the photos... It's a "series 25" (Rev-Up?)




ounces...




grams...




"Paint and chrome won't get you home".. but it's sure gonna' help me balance this model!

Roddie
Looks like you are winning the race to the starting line. Looks great! I might loo into a different drawing for the Pitts, they do look cool! I'm trying to get myself to get up and work on the P-40 tonight.

Duke, the P-40 was my favorite plane as a kid! You can "whittle it up" in no time!

roddie wrote:shoot..... still no speed Bi-plane...   yet...

That may happen..... I am about to abandon the Spit as the cowl would be a pain. A while back I was doing a "Super Solution RC" and then I was bit by the CL bug.

Anyway, the "Solution" would make a quick build and I can put a cowl on it.

Ron

BTW great job Roddie!

My Mustang cowl is going to be tough too. I'm going to draw it all up before cutting wood, but won't start seriously building until after the Yak. I love the polyhedral wings I'm seeing, if I have time I'll try a dihedral too. It's only a slight one on my plane.

RknRusty wrote:My Mustang cowl is going to be tough too. I'm going to draw it all up before cutting wood, but won't start seriously building until after the Yak. I love the polyhedral wings I'm seeing, if I have time I'll try a dihedral too. It's only a slight one on my plane.

Cribbs74 wrote:

roddie wrote:shoot..... still no speed Bi-plane...   yet...

That may happen..... I am about to abandon the Spit as the cowl would be a pain. A while back I was doing a "Super Solution RC" and then I was bit by the CL bug.

Anyway, the "Solution" would make a quick build and I can put a cowl on it.

Ron

BTW great job Roddie!

Remember guys cowls are not mandatory and you can always do this:

My second plane and my sons plane will have some version of that.

Jim

duke.johnson wrote:Roddie
Looks like you are winning the race to the starting line.  Looks great!  I might loo into a different drawing for the Pitts, they do look cool!  I'm trying to get myself to get up and work on the P-40 tonight.

Look for a drawing of a Pitts S-2B.  Wikipedia list a 20 foot span span and 18 foot 9 inch length. With a 12.5 inch span the fuselage works out to about 11.75 inches,

Jim

Here's something to get the creative juices flowing. Put a 1/32 ply doubler on the inboard side of the nose. This would allow a side mount as shown above but mounted flush against the ply. And if you use this home made mount for a modified 290 your firewall frontal area is 3/4x3/4.



Jim

   I think I have made my pic finally after a lot of looking and trying to decide if I can build this baby from scratch! have a baby bee thimble dome that I purchased off ebay but is gummed pretty bad has the standard tank will it make 12 rounds at 42 ft. I don't know yet? is any one using 3 bladed props and what is a good pitch you think? I not thinking about winning just want to have some FUN !!      

JPvelo wrote:Here's something to get the creative juices flowing. Put a 1/32 ply doubler on the inboard side of the nose. This would allow a side mount as shown above but mounted flush against the ply. And if you use this home made mount for a modified 290 your firewall frontal area is 3/4x3/4.



Jim

I had done some research on those "290" back-plates... That "tab-mount" was described, but this drawing really helps. Did these back-plates all have fine-pitch NVA's? I have x2 of these and they're both red colored. I only have x1 needle... I believe it's 128 pitch. The fuel-line nipples on the NVA's are different lengths though... and I'm wondering if only one of them had the fine needle? (I wanted to try "pressing it out"... and into a horseshoe back-plate... but I decided not to.)

I can't get a good photo... sorry

Roddie,

Go ahead and press it out and reinstall in a horseshoe plate. That's what I've done with every Reed valve I fly. Press from the needle side. Every 290 backplate I've seen is fine thread.

Jim

getback wrote:    I think I have made my pic finally after a lot of looking and trying to decide if I can build this baby from scratch! have a baby bee thimble dome that I purchased off ebay but is gummed pretty bad has the standard tank will it make 12 rounds at 42 ft. I don't know yet? is any one using 3 bladed props and what is a good pitch you think? I not thinking about winning just want to have some FUN !!      

That's a cool looking plane!! I decided to run a horseshoe back-plate/external tank, because of c/g issues on my F8F-2... (which has a relatively "short" nose...)

An external tank (or bladder) will allow for experimentation with fuel quantities. If the 5cc tank comes up "short"... you have the 8cc option, but at the cost of moving the heaviest part of the engine forward; further aggravating "nose-heavy" trouble that some of us have been dealing with on these little models.

A 3-blade prop is what I wanted to run on my Bearcat, but I can't find one with enough pitch... so I just ordered (x3) 2-blade 4.75" x 4's to try out.

I hope this helps you to get started! Good luck!  

Roddie

With my hopped-up baby stunt bee, (tank is a baby "stunt tank" from Bernie, which I then drilled out the air passage to 5/64, or 2mm) on a unmodified plastic BW backplate I get 10+ laps after a wing wrap stooge launch on my coroplast wing, which is a somewhat slow airplane. I believe I have a 6x3 rubber ducky prop on because a 5x3 doesn't provide enough pull for launching. With a 5x3 it performs similar, but I need someone to launch for me.

I expect that a 5 or 6 inch prop will have adequate economy to make this challenge.

With a clipped prop turning extra revs I don't know if you'll have enough economy to make the full run, but it will be close. With hot-fueling just before launch I am confident it will make it.

I am planning on using a 1/2 oz tank or bladder (undecided on the delivery system)

Phil

JPvelo wrote:Roddie,

Go ahead and press it out and reinstall in a horseshoe plate. That's what I've done with every Reed valve I fly. Press from the needle side. Every 290 backplate I've seen is fine thread.

Jim

3 reasons why I'm nervous about doing that.. #1; I've never done it... #2; my only "fine-thread" needle is slightly bent... and #3; I've got (one) "red" back-plate (o/s venturi) coming from Bernie, that I don't want to risk ruining if I mess up.

I'm kinda' stalled on a fuel tank right now anyway... I'd really like to "build" one... because there aren't many out there, in the capacity/style we need for this run. I've seen the tanks that Ian builds... and they're VERY well made. I have most of what I need... except the skill... and per "Ken's" comments... the tubing (for longevity).. whatever type that is... some sort of seamless metal tube... but definitely NOT Brass... (I'll bet that the sm. dia. "top portions" of telescopic antennae might make good plumbing...) I may install a uni-flow tube in a sm. (Perfect) wedge-tank. I need to obtain better soldering equipment... (a couple small pencil irons just doesn't cut it) I "do" have .005"/.010" sheet Brass, Brass/Copper tubing and Silver solder/flux supplies to build a tank for this race though... either way; I'm going to run a uni-flow vent.

Roddie, my local hobby shop has a lot of smaller perfect brand control line tanks. Do you want me to see if they have something that would work?

Jim

Common brass tube gets a bad rep because it will eventually fail, and it corrodes to produce green gunk.  To limit the risk of failure, soldering the tube ends in the tank is important.  Also what kind of life span are you looking for?  A decently made tank with common brass tubes, kept reasonably clean will be good for hundreds of flights.

Now, if you go to the auto parts store there is copper tubing for a oil pressure sender in (I believe) 1/8 OD which is reasonably suitable, easy to solder, and annealed so it is easy to form.  It is still important to affix the inside ends in place rigidly.

Phil

JPvelo wrote:Roddie, my local hobby shop has a lot of smaller perfect brand control line tanks. Do you want me to see if they have something that would work?

Jim

Thanks Jim... but I'm not really sure what road to take yet. I have a few small narrow Perfect wedge-tanks... and I have some Copper/Brass tube. I need to read a little more before making choices. I'll probably end up with 2 or 3 different options to try.

Thanks again,
Roddie

Don't over think it Roddie, all you need is a tank that will work.

I will probably use a tanked bee myself, but If I was going to run an external tank I would open it up, clean it out, solder the pickup and press.

This tank doesn't have to last forever just a few runs. If you want to have a real reliable tank then modify it later on.

Ron