Pee Wee Horseshoe back plate

You are likely to find that this fiber filled Zytel is going to be entirely too coarse to be able to produce a sufficiently smooth sealing surface between reed and the venture.

It runs!  Needle setting is extremely sensitive. Maybe my intake is to big affecting fuel draw? I can also lower the reed circlip closer to the reed. Seems like I gave a few thousands too much reed float compared the metal pee wee tank or the heli backplate.

My tach didn’t work under the fluorescent lighting. Didn’t sound too high of an rpm.

Man! That was great. I think you are dialing in nicely. Who knows why the run wasn’t super steady, but there are a ton of factors involved.

I don’t think it’s a reed float issue though. I totally want one of those backplates!

Perhaps it will run smoother with the lower weight black flexible prop.
Hows the internals any signs of heat damage?



RPM was 12.8k to 15.7k at the end when it leaned briefly.
The NV could be leaking, if reed float is too gaped out it
could lag performance. The grey prop is giving it a workout
all the same. The TD .020 has to work hard to swing that
prop let alone the reed engine. The fuel draw won't suffer
the way you have it rigged up. Typically the engine would
not use that ID fuel line since you have a .049 NV on there
it fits. I get better fuel draw off the non clear more flexible
silicon fuel line. It has a smaller ID and does not have to
work so hard to pull the fuel out of the tank.

Nothing deformed or melted after the run.  I used a brand new nv seal when I inserted the needle valve into the backplate. I don’t have a bladder to try to see if it’s a fuel draw issue.

That's great,  some ideas to fine tune things like a good crank case surface
seal with 1 or 2 Pee Wee gaskets worth trying. Lower weight black prop see
how it responds, NV seal from air leaks with silicon fuel line. What size IV line
is that? The brass is beat up and could be an issue with IV line as it does not
seal as well as silicon tube. IV line is vinyl and gets harden up over time.

If need be reduce the reed float distance worth a shot no doubt if none of the
above has improved things.  




There is no .010 to .020 silicon fuel line available on either of the Cox engines sites.
Note this size is for the .020 engines:
http://www.exmodelengines.com/product.php?productid=17719&cat=264&page=1

This is good 1/2A  .020 to .049 silicon tube you can buy, I have had good results
with the thirsty TD .020.
https://coxengines.ca/cox-.049-1-2a-silicone-fuel-line-3.html

Another option, Dubro small silicon fuel line is 1.5mm ID great for the TD .010 but not
so good for the TD .020. Might be ok with the reed .020.
I have notice a difference in performance fuel draw stutters if the ID is too big
with TD .010's It's like a large dia. straw harder to draw from, promotes air
in the line.

Great job! Even little issues are not too big. Having an engine that will run again vs having a engine that doesn't is a big plus in my book! Like Ron, I would be interested in one of those too if you get into making them.

I replaced that deformed NV seal before the run. I do have small silicone tubing somewhere. I’ll have to find it. I’m using a piece of 049 fuel tubing which maybe too big.

.

I made the reed seal area .005 taller and .010 wider. There isn’t much there to try to polish up.

I want to avoid as much post processing as possible.

Also I don’t have enough fine thread NVAs to harvest from postage stamp backplates to make these. Users would need to provide their own.

I could redesign the back to use a TD .020 venturi and NVA since these are available new again.

This new resin printer has 25x50x50 micron resolution. Could definitely provide cleaner parts but not sure how well these would hold up to heat and nitromethane in the fuel.

https://www.matterhackers.com/store/l/zortrax-inkspire-uv-lcd-fully-assembled-3d-printer/sk/MSPHQELF?utm_source=MatterHackers+Newsletter&utm_campaign=56b3b1292b-EMAIL_CAMPAIGN_2017_01_30_COPY_01&utm_medium=email&utm_term=0_dccd3cdce8-56b3b1292b-123710005

Nice work!

Maybe you could use a junk crankcase to lap the backplate sealing surface? Or maybe some liquid gasket material instead of the paper gasket?

A little dab of glue compatible with the plastic component of the printing material would probably eliminate any leaks from around the fuel nipple.

My two cents only... Keep up the good work with this and other printing projects, I am following with great interest

Great looking work! A simple way to see if it is a fuel flow/pressure issue is to lightly pressurize the tank with a fueling syringe, close the vent line and leave the syringe attached then do a bladder start and run. I thought (I have practically no pee wee experience) that it sounded like it was a fule flow issue. Either way, you have done some really beautiful work!

Created a mount for a TD .020 venturi and needle valve assembly. Now I need to find my 11/64-40 tap.........

Just going on a whim here, but does the .020 needle assy look different from the .049. I do not have a .020 assy here, only an .049 so I do not know what the difference is. Just asking as the rear of the backplate does look very different.

For sure should have more performance with that setup, could also use a GM .030 RC Carb

Ok so here is a second run. Basically different parts - short block, backplate of same design of previous run, and different fine thread NVA. Smaller fuel tubing. Cox black 4.5x2 flexible prop. Cox 25% super power fuel. Basically can I recreate the run to make sure the first backplate wasn’t a fluke.



Few pics after the run.

WOW!!! That is sooo cool! Great work!

The second run was much better , Looks like a winner there . Ilike the TD mount too . That printer (Zortrax) seems amazing the things they can make today are to . For mas production but would need to cover the overhead first of the 2100.00 and what the material is ?? Fuel Proof ?? See if they can send a sample heck havem print a back plate for testing

Jason! ... very good work! ... I like how the engine runs!

Looks like your extra efforts have paid off the engine is running great!

RPM Readings:
After adjusting the NV steady for a bit at 18,007 rpm to 18087 rpm best brief peak.
Settled in at 17.8k
See how the lower weight black prop has helped pick up some rpm in conjunction to your fixes.
4.5x2 Prop @ 18k rpm: 6oz thrust / .034hp - 25.4w / 34 mph prop pitch speed


What plans do you have for the engine is there a plane in mind at this time?
A throttle sleeve would be great to have on tap to test with the engine.
Whatever it goes on if you can keep the all up weight no more then 5oz
it will perform very well.

WHOO! That was really slick! Nice run, smooth sounding. I continue to be amazed at the capability of you and your printer. Thanks for sharing.

Jason, that's the cat's meow. Nicely done and that video was very rewarding. Just too cool. I like it a lot. Ken

Thanks for the compliments guys. Just trying to bring life to orphaned pee wees with broken dicast backplates.

I plan to print the latest version tonight with the modifications I made to the reed area. I added a small Cox logo to the side to see how it prints. I'll also print one of the venturi backplate mounts to test out. Still looking for my .020 venturi tap..........