Fun with Generic, Non-Threatening Title

I never noticed this small hole between the guide-rails.. It was hard to photograph. It doesn't seem like it would have been functional..   Anybody have a pic of the mating-mount in a Testors ARF model?

 Nobody ever saved the broken airplane.. just the engine! If you still had the model.. the engine would probably be in it. Of course.. if you had a fuse, you could bench-run the engine by clamping the fuse to a sawhorse!!  

Work of art roddie. New life for a purpose built engine. Could the same thing be done with like diameter aluminum tubing? Might save some weight but machining would be more difficult.

Good job, Roddie. I'd passed on the PVC path, but I'm glad you ran with it so we could see how it comes out. I've settled on two different mount designs, one heavy and one light. I deviated from my mount building to build a fuselage to mount the engine in. It's not supposed to rain Thursday, so maybe I can test fly it then and know if this is feasible or just an interesting experiment.

The Deviant Mark

rsv1cox wrote:Work of art roddie.  New life for a purpose built engine.  Could the same thing be done with like diameter aluminum tubing?  Might save some weight but machining would be more difficult.

The PVC has promise.. because of the way it's made. I believe it's extruded.. and being as rigid/dense as it is; permits slicing end to end.. having it spring-back against itself. This would allow for a squeeze-fit.. providing it's notched correctly to fit around the top of the case and cylinder. To tell you the truth.. the ear/rail on the side of the case could be trimmed off completely.. because the engine is now being held at the top of the case.

Pipe bomb speed!! I love it.
Phil

chevyiron420 wrote:Pipe bomb speed!! I love it.
Phil

Yea.. it seems like a worthy endeavor for this little engine that's so despised for it's post-wreck non-usability. Imagine a stubby little speed model.. with a 12" wingspan.. 30 foot lines..    sturdy music-wire gear placed well-forward for easier ROG launches. If I get this mount worked out.. an airplane like this would build quickly.. non-scale/experimental.. no-frills.. who cares if it crashes fun! Nothing ventured.. nothing gained.

For anyone wanting to give the 3/4" PVC pipe-mount for Mark's modified Testors back-plate engine a try; I cut my pipe to 2.125" long. This should provide room to hold the engine.. with room behind it to utilize a 3/4" hardwood-dowel firewall. I'll see if I can get V.2 worked out tomorrow. I'm going to trim/remove that channel/rail-mount from the side of the case and eliminate the slot in the pipe for it. This will help the pipe close tighter around the top case-edges better. The cylinder and the raised cylinder-boss on the case will lock the engine in place in the pipe.

Okay.  I finally got some time to get back to the Testors mount.  This is what I’m going with right now.  It’s not elegant, not sleek, and not polished.  But it’s made of scrap wood so it’s cheap.  It only weighs 12 grams bare before fuel proofing.  And it clamps the engine in tight.  It looks unwieldy, but there’s a reason for the shape.  I put that rear try on it so I could use it to hold a fuel tank.  And the width was chosen for the airframe I plan to put it in.  I figure I’ll make a variant of the coroplast PT-19 fuselage for this, but with a fixed stabilizer rather than a stabilator.  So the width of this mount is the same as that of the formers for the coroplast PT.





Here is somewhat how it will look in the new airframe.  This is the airframe for the Medallion powered PT-19 I made, so on the next fuselage I’ll be making a different cylinder cutout and different mounting screw holes.  But you get the idea.






I keep thinking I may just cut the fuel tank tray off the back and save the weight.  Cut down, I’d imagine the weight would only be 6 or 7 grams.  I’ll have to remember to weigh it with the engine in place.

The Bare Mark

Wood engine mount system and plane look great Mark, waiting for test report, excellent work and ingenuity.

Nice job Mark!  The 3/4" PVC would be a lot heavier I think.. but if I can get the engine to snap-in and hold securely, I could try a cool firewall mount for a profile fuse that I sketched-out last night. I think I'm going to have to cut that slotted rail off the side of the engine's case to make this work.. It's too close to the front-limit of the case-fit and a slot for it really weakens the pipe's clamping ability. I need a 3/4" hole-saw and don't have one in my assortment..   I used a paddle-bit to drill the first prototype's hole.. and it's wack.. not to mention hard to do.



I'm cutting another length of pipe to slot differently. If I can source a smaller hole-saw, I'm hoping to only have to cut a 2nd full-length (razor-saw) cut..to create a slot slightly narrower than the case and one hole-saw cut strategically-placed in between to surround the cylinder.



Good luck with flying your coroplast variant!

So I got this almost wrapped up.  For landing gear I made this a mono-wheel to save time and weight.  Besides, I only had one wheel sitting on the table unclaimed.   This pretty much turned into a little Testors power pod, which seems like a decent result.  Put together, the power pod weighs 3.1 ounces, or 90 grams.





The airframe is done with the exception of bending up an elevator pushrod.  It weighs 3.95 ounces.




So, guessing that the pushrod and various screws will add a couple of tenths of an ounce, we’ll call the estimated ready to fly weight at 7.3 ounces.  This compares favorably with the Cox Bee powered coroplast PT-19 I built at 7.65 ounces.  I’ll post the actual if I remember to weigh it.  It’s the middle of the night, so I’ll get assembled pictures tomorrow after I make up the pushrod.

The Forgetful Mark

Okay.  Ready for the weather to clear up and test fly.  The airframe is ugly, but it’s only meant to be a quick fixture to hold the Testors engine.  Gentlemen and Lady, I present The Pipe Bomb Special:





I only built the fuselage, the wing I pulled off of one of the PT-19’s I built earlier.  I deviated from Keith Morgan’s plans in that I made a stab and elevator instead of a stabilator.  I thought about making a separate hinge for the elevator and stab, but as this was just a quick and dirty build, I just slotted the coroplast for the hinge.




The Ugly But Functional Mark

Congratulations Mark! Did the weight come in where you expected? What size is that gear strut wire? It looks heavy to me..  Does the model balance comparable to your other variants? You're RTF engine-pod is approx. .5oz. heavier than a Baby Bee engine w/prop.. so removing that strut and wheel might make a big difference in how well it fly's.

FWIW.. I don't think it's ugly at all. Do you have a 1.25" plastic spinner? Slotting the top of the fuse for a profile canopy would dress it up some.

Great all around effort Mark.  Looks great, but a bubble canopy would dress it up.

roddie, you would be surprised just how light that nose wheel is.  I have a couple and I couldn't believe the lightness.  

From the peanut gallery..........

Bob

Hmmm....Just did a search for a small/1/2A canopy on Omni & Tower +ebay. Seems they are difficult to find.

Looks Pretty Good there Mark, hope it flies Ok for you (report please) Good to see your putting that stuff to good use . Eric Those wheels are really light Bob just read your post and had to go back and LOOK

Slice up a pop bottle to get a canopy, or recycle some packaging.

Looks good.
Phil

rsv1cox wrote:Great all around effort Mark.  Looks great, but a bubble canopy would dress it up. [...] Hmmm....Just did a search for a small/1/2A canopy on Omni & Tower +ebay.Seems they are difficult to find.

http://www.ebay.com/itm/Enterprise-Blue-Chip-Store-Display-Accessory-Pack-NIB-/301273257243

Penn Valley Hobby Center wrote:Enterprise Blue Chip Store Display Accessory Pack. Contents include, 12 1-¼” Spinners with back Plate, 8-3” Canopies, 12-4” Canopies, 24-½” Pilots and 18-1” pilots. Neat Collectable. New Old Stock.

$10 + $6 shipping. I bought one, the canopies are suitable for both 1/2-A CL planes, FF and rubber powered, comes with matching pilots ready to paint.

Mark, it looks excellent, with a bubble canopy it'd look like a generic WW2 fighter, like a lot of CL's do.

roddie wrote:Congratulations Mark! Did the weight come in where you expected? What size is that gear strut wire? It looks heavy to me..  Does the model balance comparable to your other variants? You're RTF engine-pod is approx. .5oz. heavier than a Baby Bee engine w/prop.. so removing that strut and wheel might make a big difference in how well it fly's.

Roddie, the weight came out about where I expected.  Final weight was 7.4 ounces after balancing.  It was slightly nose heave at first, but easily fixed.  This shows two more great things about building with coroplast.  To find the balance, just mark the balance point on the wing, make a couple of needle holes, and pass a thread through the holes to suspend the plane.  To balance the plane, I use a hot glue gun.  I use the gun to fill the flutes at the back of the plane with glue.  That allows me to add a couple of grams at a time until the plane balances out just right.





The gear wire is 1/16".  That's about as small a diameter I can go without it being too bendy.


The Expectant Mark

GallopingGhostler wrote:

rsv1cox wrote:Great all around effort Mark.  Looks great, but a bubble canopy would dress it up. [...] Hmmm....Just did a search for a small/1/2A canopy on Omni & Tower +ebay.Seems they are difficult to find.

http://www.ebay.com/itm/Enterprise-Blue-Chip-Store-Display-Accessory-Pack-NIB-/301273257243



$10 + $6 shipping. I bought one, the canopies are suitable for both 1/2-A CL planes, FF and rubber powered, comes with matching pilots ready to paint.

Mark, it looks excellent, with a bubble canopy it'd look like a generic WW2 fighter, like a lot of CL's do.

I saw those before, but I didn't realize how much stuff came in the package. I just ordered one. That should give me a little material to work with.

The Planning Mark

batjac wrote:

roddie wrote:What size is that gear strut wire? It looks heavy to me..

The gear wire is 1/16".  That's about as small a diameter I can go without it being too bendy.

The Expectant Mark

The gear wire looked a lot bigger in the above photo. Have you had a chance to get a flight in? How did you go about removing the tank to end up with the round back-end?

roddie wrote: Have you had a chance to get a flight in? How did you go about removing the tank to end up with the round back-end?

No flight yet. Still raining. I have to wait a couple of days after rain because I fly from a grass field that's soggy after a rain.

To cut the tank, I just used a razor saw and cut the back of the tank off where the air tube is. That leaves about a quarter of an inch where the round portion is. I then used an aluminum sanding block to square it up, and then trim off all the fuzz with an X-Acto knife. Quick and easy.

The Soggy Mark

batjac wrote:

roddie wrote: Have you had a chance to get a flight in? How did you go about removing the tank to end up with the round back-end?

No flight yet.  Still raining.  I have to wait a couple of days after rain because I fly from a grass field that's soggy after a rain.

To cut the tank, I just used a razor saw and cut the back of the tank off where the air tube is.  That leaves about a quarter of an inch where the round portion is.  I then used an aluminum sanding block to square it up, and then trim off all the fuzz with an X-Acto knife.  Quick and easy.

The Soggy Mark

Thanks Mark. What a drag.. You must be Jones'n to fly.. given the several models you've built over the last year. I've lost count.. but there's the Lil Toot last April.. the Pee Wee-modified Sea Fury, the 3 BTC series models, the Coro-Plast Duplex Delta and PT-19's... Holy crap!

I removed the back of the tank by cutting along the "flat".. so my air-intake will share the needle-access hole in the side of the pipe. I'll try filing a notch through the housing to expose the fuel-nipple. A 1/2" hole through the pipe should allow clearance for the needle on one side.. and R & R of fuel-line on the other.



I found a 3/4" hole-saw to hopefully form a saddle to surround the engine cylinder's base in my PVC pipe-mount.

Has there been a test flight on the pipe bomb special yet?

Here is a dis-assembly of a Testors P51. I call it the One Screw Wonder, because it is held together by only one screw!! Not anywhere near the complexity of a Cox Stutka.  Remove just one screw from the bottom, gently lift the plastic belly pan up and away from the fuse. take a long thin pry bar ( kitchen knife i=or screwdriver) and pry up on the locating pins on the port and starboard wings. Pop them free and continue to twist the belly pan back and forth while pulling back untill the motor pops free of the front cowl. BINGO totally dis assembled. the one piece landing gear assembly is held in place by the single screw that hold the top and bottom together, while the bell crank is held in position on a plastic shaft or pin between the top and bottom. SO easy...even a caveman could do it!!









I tried to get a good picture of the engine mount. The front cowl has a cut out for clearance of the the spring on the rotomatic starter. The engine just rests on the plastic
"formers" and is held in place by the Clamshell of the upper and lower assembly, with openings located for the fuel drop and Needle Valve. This one looks to have been run with the original small amount of  fuel that was packaged with the "FLY-EM" package and then stored away. I cleaned up the engine and it started right up with a few flicks of the starter. Ran a slobery rich tank and the refilled it and needled it up to 12500  RPM
Sat it down( unrestrained ) on the workbench (stooge) and as I was reaching for the camera, she leaned out screaming a DRAMIATIC increase of RPMs and flew off the work bench about 6-8 ft ran out of gas and landed in the weeds!! IT Runs it Flys, but I don't think with the small tank size  that it would last two or three minutes in the air.