Pond Skipper

Ahh bummer!
I always oil every engine when sourced and keep them indoors out of the garage to include the shed, trunk O car, tin box on der back porch etc.
I have a few ran this year that are do for oil won't be in use for who knows when now. Will bench tach the GM this weekend hope to see 22k loaded.
The wide blades should give some reasonable thrust and won't break smacked into the grass. I have broke a few already this year.

Pond Skipper

From Sunday - would make a good oil painting.

Pond Skipper

 https://www.youtube.com/watch?v=WyKwCxfHxf0 This one can be viewed in HD 1080p. go to setting bottom right corner (the pinion gear) of the player for HD quality.
Apparently my last effort could only be viewed at 480p / with the plane being so small HD is the only way to go.

Pond Skipper

Flew today with the APC 4.2 x 2
In the hand 21,400 rpm
23,600 rpm unloaded
Great thrust with a mix of speed throttle response was very good with this prop but the 2p limited to average 44.7mph level.

Pond Skipper

Picked up a KK crank case pressure tap slash back plate for a TD .051 notice the inside hole is half the size dia of the average needle with the nipple being about the same size of a TD .049 at the carb. Hope it does well with a 1oz hard tank.

62.8g with the radial mount / beams removed:

MJD

My Feedback: (1)

How's that pressure tap going to work with a carb I wonder.

What, this thing gets an .051 now..?

Pond Skipper

I am not sure how the carb will respond KK didn't design there backplate to work with a Tarno carb. I may go with a muffler tap and save the back plate for a CL project.

Lol I have been thinking of using a 1/2A on the plane but would have to cut back the firewall a whole inch to compensate for the weight.
The G-Mark .030 shown in this thread is possible too. The airframe is strong per the rolled fuse method but I would have to reduce the tank size to have enough room - not willing to lower run time so will stick with the TD .020.

CafeenMan

What about a piped Nelson .40?

Pond Skipper

Could use one of my round 1oz tanks for the .051 to make another rolled fuse type plane that suits the dia. of that tank and would design the plane to handle up to a TD .09. I would copy the design clone the wing which would go to 4.5 x 26in. span and 17in. fuse.

Pond Skipper

lol Cafeenman!
My friend Mark had one on a quickie 500 impressive power! If they could just make a Nelson .040 I would slap that puppy on der plane in a heartbeat.

combatpigg

My Feedback: (3)

That .051 will be at the heart of some interesting projects..!
It's nice to be able to do away with the beam mounts for certain types of planes.

Pond Skipper

Yes need to make good use of that engine it was lapped and tuned by a French enthusiast who was heavy into competitive national level racing. He had nixed the tabs and had another radial mount. Compression is very snappppppy. The race engine had a bored venturi and kk needle. Cut beams for a radial mount that incorporates the original backplate and aluminum ring with three mounting holes. Might of been one of Harry's efforts back in the day. I did some mods to suit my needs and wants including polishing the case and muffler on a buffing wheel.
The next plane needs to be able to handle the weights / sizes of .049's to 09's is the plan. Then a .15 to 26 size to cover the entire spectrum of engine types I have on hand in these two bins and tucked away in boxes. Only one in the batch not ready to run a GM .061 missing the throttle barrel for the carb. I need to fabricate one if I should ever want to hear it sing again.

Pond Skipper

Some prop testing again this weekend:

Cox 3 blade 3x2.5 gets 22k ish the torque required me to dial in some right aileron easy to set the needle with the prop and no overheating.
Didn't expect much but had to try speed was reasonable but not enough.

Tried a cut down APC 4.2x4 to 3x4 and left it constant cord, just snipped the ends for a simple square tip as was not sure how much sweep and taper I would go with. I was able to get 19,300 in the hand and 20,800 rpm as an average unloaded level. The load seemed constant dives did not increase much over 21.4k. 80 mph on paper about 60 mph in the air.
Needle settings seemed easy to hold so tonight I formed the tips looking for 24k rpm level unloaded for theoretical 91 mph so perhaps I will finally surpass 70 mph with a stock engine. Had to use the cox rubber spinner set up to match the prop hub and avoid using a long bolt and 1/2A aluminum spinner to help reduce vibration. 3in dia doesn't produce much thrust at 21k - now that the tips are cleaned up 24k should help.

Here's the prop ready to roll:
3x4

combatpigg

My Feedback: (3)

Nicely done..!
I think you could scrape the top side of the blades down if you want it to unload better. This material scrapes / shaves pretty easily.
It's the mass out towards the tips that bog the engine. I'd love to see you make this 4 pitch prop put that model over the top.

Pond Skipper

Thank you CP.
Will post a new vid if this prop exceeds the 4 x 2.5
Yes straight cut tips now formed and thinned should do 23-24k -will tune / thin the prop hair more if need be trying to save some strength to avoid breaking the prop in the grass.
I noticed the mold flashing around the hub after taking the pic lol. I used two small flat files to reduce the bulk and shape then sanded with fine sandpaper. The underside of the airfoil at the root is still bulky but the extra beef may save from snapping off a blade so will keep for now and get another reading next weekend.
Im ready to close the book on this design once I know what prop hit my goals. The Cox 4 x 2.5 and APC 4.2x2 should be first for overall thrust and reasonable speed. Its really down to what prop for all out speed with this plane. Knowing the dimensions and weight should give me enough data to build a faster stock TD .020 plane later down the road.

Pond Skipper

Did some flight tests with the new thinned out prop and tips reworked as shown.
In the hand 21,600
Best pass 24,260 for 92 mph theoretical - given the dia of the prop has the speed looking like 65 ish at best.

Currently I have enjoyed the additional thrust over speed to hold and pull out of the turns better so will stick with the 4in dia. props.
Unless a carbon 3.8 x 3 should magically appear.

DeviousDave

Bob Mattes does glowbee/nelson conversion heads for the .020, they run a lot faster after he gets done with them..

Pond Skipper

Yes been tempted to hop up a TD .020 I have read Bobs tips and seen his work in action, most impressive.

Pond Skipper

As shown with prop and spinner 43.6 oz this may be the lightest stock .049 by cox - nicknamed the postage stamp engine do to its minimal backplate. I won this on ebay to see how it would match up to the existing firewall... Its close. It has two ports ground in for its dual exhaust with strong mint compression and a matched cylinder piston assembled back in the day when Leroy was running the show.
To note the TD .020 with aluminum back plate, throttle sleeve, spinner prop 26.4g. for a difference of 17.2g .
If ran with the APC 4.2 x 4 it should make anyones .020 plane scream for mercy exceeding its original speed with a huge leap.

Pond Skipper

The red dots may be drilled out to suit the exsting firewall. If ran without the long allen bolt and no spinner and fitted with one of my older thin walled vintage cylinders to reduce weight further the final step would be to grind down the steel and aluminum cooling fins as the 4.2x4 prop should have the engine running cool enough to get away with this.
I could see the weight around 36g thats light for 1/2A.
Weight of bolt /spinner 3.6g
With short bolt /washer .9g

MJD

My Feedback: (1)

IIRC the VA .049 Mk1 - a very light engine for the displacement - was about 42g, so 36g definitely qualifies as light!

Pond Skipper

Yes 40.9g with just a short bolt n washer

14.5g thin walled cylinder and plug
16.2g thick walled and plug

Now with short bolt / washer and thin walled cylinder 38.6g with APC 4.2x4
Will grind down the steel and aluminum fins tonight to see if I can hit 36g.
The Peewee with 3blade prop and spinner 30.3g

Pond Skipper

Ok took down the cooling fins
Drum roll final weight 35.7g as shown with prop!
Only 5.4g more weight than the PeeWizzer yet .029 more displacement.
9.3g more than the TD .020
Need to spiff up and polish the lil gem yet for now here are some pics.

Mr Cox

What, you removed the cooling fins for a whopping 3g weight loss and risk to have an engine that overheats?
1oz of fuel is 28.4g, that's how much the weight will change during one flight alone, are you sure you will feel a 3g difference on top of that....?

The extra fuel needle to compensate for the poor cooling might be more than 10% and then you'll need more than 3g of extra fuel...

Pond Skipper

Hey Kris sound absolutely insane huh lol I started off at 43.6g and ended up at 35.7 for an additional 7.9g reduction in weight. I now only have a total of 5 stubby fins left.
I have few tricks for cooling a batch of requested custom blend 25% all castor / 40% nitro - prop selection is the thin blade narrow cord APC 4.2 x 4 verses a common thicker foil and cords found with the cox props such as 6 x 3 or 5 x 4 even the 4.5 x 4 thus load has be greatly reduced allowing runs that will stay much cooler. This reed engine wont turn up blistering rpm but can atleast now be ran to the max limit of the reed. I plan to test with a higher performance mylar reed over the older brass reed and compare. I may try a high compression head if the reed can handle over 22k rpm. I plan to use a custom made .65oz pill tank dry weight 8.8g see pics one full reading one empty for reference. The idea is to have more power than a .020 that is low enough in weight to add to the nose of an existing .020 plane. A typical .049 won't fit weight or size wise on a existing .020 plane. ref pics showing the footprints.