How I made my ASP 25II fly

[Tim Thompson]

Not being able to buy smaller OS motors anymore, I gave ASP a try.  Unfortunately they only come in RC versions. Now I know I could just wire the throttle open and it would work, but I wanted a CL style motor. So I asked about using nylon spacers here on Open Forum and found that I could.  So I got a nylon spacer from local hardware store. An inch long, half inch in diameter and a quarter inch hole through the middle. Not having a lathe, I used my Dremel with a Christmas tree burr and shaped a venturi shape the best! Could at the top and a double D shape at the bottom like the RC carb. Then I drilled a hole to accept a spray nozzle from an OS40 LA. This hole is just above the crankcase. Wrapped a piece of tape around the bottom of the venturi and put the O ring from the RC carb on it then clamped it in place. Next I used a tongue muffler from RSM that fits an OS 40 motor, direct bolt on. I  next mounted the motor on a board with a 8X6  Top flight prop, some  10 22 fuel ,primed it and she started in 4 flips
Next run she started in 1 flip. I ran a few more tanks through her then changed to an APC 10X 3 prop. A little fiddling and I got her to start 5 times in a row with one flip! So I bolted on my little plane simular to Phil C's Plugger and flew her yesterday. I haven't been able to fly in 2 years  so Doss Porter talked me into test fly it with the promise that if I got to dizzy he would take over. Well we launched her set slightly lean and boy did she fly fast! Pretty soon I was dizzy dispite spotting every lap so Doss took over!  And I fell down, lol! But any way I'm pretty impessed with my  $48 motor from Hobby King!

[Tim Thompson]

Picture of it

[Target]

Awesome success story,  Tim!  Congrats.

[Perry Rose]

The ASP .52 r/c with a Jim Lee venturi is a good set up for c/l.

[Tim Thompson]

The ASP .52 r/c with a Jim Lee venturi is a good set up for c/l.

Thanks for the suggestion, I  was thinking that the ASP  52 might be a good choice for an unfinished plane that I started before I got sick 2 years ago and gave away it's OS 46 LA.

[Steve Helmick]

I'm curious to find out how well the plastic holds up to the clamping drawbar, so maybe you or anybody else with experience with this configuration could report back? I've always gone with an aluminum venturi if I needed to use the drawbar. I have also installed the spraybar where the drawbar goes, like a Super Tigre, but it's a PITA.

While I have a lathe at home, I start roughing the bell mouth with a 60 degree single flute countersink...which you could do with an electric drill or drillpress...run it as slow as you can. I finish it up with a #11 Xacto blade, again, running it as slow as possible.
  Steve

[Tim Thompson]

Awesome success story,  Tim!  Congrats.

Thanks  Target!

[Tim Thompson]

I'm curious to find out how well the plastic holds up to the clamping drawbar, so maybe you or anybody else with experience with this configuration could report back? I've always gone with an aluminum venturi if I needed to use the drawbar. I have also installed the spraybar where the drawbar goes, like a Super Tigre, but it's a PITA.

While I have a lathe at home, I start roughing the bell mouth with a 60 degree single flute countersink...which you could do with an electric drill or drillpress...run it as slow as you can. I finish it up with a #11 Xacto blade, again, running it as slow as possible.
  Steve

I'm curious too! And I'll try to let everyone know what happens.
Many moons ago I used to port and polish heads. It's normal for me to carve with a rotory tool. And my 8200 Dremel feels a lot like a die grinder. Plus being battery operated it only takes a few seconds to make nylon flakes fly all over the place! Only took about 15 minutes to make it. Mounting the spray bar above the crankcase had me wondering, but no more. The spacer only cost 35 cents  so I didn't have much to lose if it didn't work. But it works amazingly well!

[RknRusty]

Makes you feel proud to get in the shop and innovate something like that, doesn't it. Good work.

What was that nylon spacer meant for, rather what department, plumbing, electrical, etc?
One of our Stunthangar members made a venturi for a combat engine from an APC prop hub. For a Norvel, if I remember correctly.
Rusty

[Perry Rose]

The spacers are used as "stand offs".

[Tim Thompson]

Makes you feel proud to get in the shop and innovate something like that, doesn't it. Good work.

What was that nylon spacer meant for, rather what department, plumbing, electrical, etc?
One of our Stunthangar members made a venturi for a combat engine from an APC prop hub. For a Norvel, if I remember correctly.
Rusty

Although I  blantely stole ideas from Mr Cartier, ( if you steal ,steal from the best ) I  made all the parts for the plane myself. So yes it did make me feel good! The plane itself flew better than I expected and I just love the motor!

The spacer is in the hardware department at a very well stocker hardware store we have called  Fresno Ag.it's in the section that has special stuff, like nylon,aluminum and stainless steel.  The drawer it was in just said Nylon  Spacers. There is another drawer that says Nylon Standoffs ,but they are smaller. The drawer that has Aluminum Spacers only has them up to one half long.
True Value and OSH  should have the same thing. I always go to Fresno Ag because its my to go to store.

[Tim Thompson]

 Although I'd like to say everything has been going smoothly, I  kan't. Next time I tried to fly it, she would die on me in about 3/4 lap like someone flipped the switch. It would be dry on fuel. So I called RSM looking for some guidance and Eric made me a new tank and shipped it for free! What a guy!  In the mean time I put a wedge tank on it, it didn't do much better.  So I called RSM  up and told Eric I had to eat crow, it was not the fuel tank, but he refused to let me pay for the tank he gave me. Then the next week I got a bad launch, the poor airplane came in at me faster than I could run and she broke. So last week I got her all repaired and tried again.  We set her off at a nice sounding 2 cycle and she went around real fast and ran the tank dry! Next flight I put the prop on backward and got the best flight yet! That was a 9X4 APC prop. Tower didn't have any 9X3 , next time I'm going to try putting a couple layers of panty hose.  If that slows her down then I need to have a smaller venturi made. Got my fingers crossed.

[Chris Sarnowski]

Hey Tim, since you have one, could you measure the R/C carb neck and report back? I am wondering what size venturi (OD of the neck) it would take. Also wondering what the inside diameter of the venturi is on your setup.

Thanks, Chris

[Akihiro Danjo]

Tower didn't have any 9X3 , next time I'm going to try putting a couple layers of panty hose.  If that slows her down then I need to have a smaller venturi made. Got my fingers crossed.

You can use Master Airscrew 9x4 G/F nylon prop because the actual pitch is about 3".
Aki

[Elwyn Aud]

I See some of the combat guys using ASP'S. Looks like someone is making a C/L venturi for them.

[Tim Thompson]

You can use Master Airscrew 9x4 G/F nylon prop because the actual pitch is about 3".
Aki

Thanks, I'll try that!

[Tim Thompson]

I See some of the combat guys using ASP'S. Looks like someone is making a C/L venturi for them.

Yes some guys are. Like Just Engines.com.  In the U.K. but buy the time they get here they cost more then the whole motor.  The whole point of this project is to make something work that doesn't cost a lot of money or take much time

[Tim Thompson]

Hey Tim, since you have one, could you measure the R/C carb neck and report back? I am wondering what size venturi (OD of the neck) it would take. Also wondering what the inside diameter of the venturi is on your setup.

Thanks, Chris

The carb measures .511 inch  outside dia. The inside dia is .231 inch. That's a smidgen less than 6MM. My homemade venturi is .250 inch. Or fourteen thousands  bigger than 6 mm. BTW the remote needle valve assembly will bolt direct to the back plate of an OS 25 FP.

[Pat Chewning]

This spacer, made from Acetal (Delrin) is available from McMaster-Carr:   1/2" OD,  1/4" ID, 1" L

https://www.mcmaster.com/#93717A436

[Tim Thompson]

This spacer, made from Acetal (Delrin) is available from McMaster-Carr:   1/2" OD,  1/4" ID, 1" L

https://www.mcmaster.com/#93717A436

As I have stated above nylon spacer is exact same dimensions and only cost. 35 cents from local hardware store.

While on the subject of size, the ASP  spray bar in the RC CARB is a tiny skinny little thing much small than the OS spray bar that I'm using.  I  can only guess, but I think that the square area of my homemade venturi is less than the ASP carb.

In the picture below is also an OS  venturi from an OS 40 LA. Almost seems like it would work installed upside down.

[Chris Sarnowski]

Hi Tim, thanks for getting the measurement on carb neck and ID for me. I have a magnum 28xl that is set up similar to your ASP 25, with a home depot spacer and OS needle through it. I believe the ID is 1/4" like you are using. Those nylon spacers don't machine very well, but you can do much better with Acetal/Delrin. It is the plastic of choice, I would say, for making venturis. Anyhow, the 28xl likes to run a wet 2 stroke and I think I had an APC 10/4 on it. Basically I copied Fred Krueger's setup from about 10 yrs ago as documented over on Stuka Stunt. Launch RPM was about 10,500 I think. It's been siting in a box for a few years now, but may get use again on a P-Force next season.

-Chris
 

[Tim Thompson]

So when I read about using panty hose and an O ring to hold it on the first thing that came to mind was to make the O rings like I do for smaller electric models prop savors. Cut a piece of rubber band that's used for ponytails. Then super glue the small piece together to form the size that I want. Never had one to break as a prop savor, shouldn't break wrapped around a venturi.

Next I put 2 layers on the venturi and did not change anything from the way I last flew it.
Well today it flew just about right. It was a very injoyable flight! Next week I'll try a 10X3 ,but will be ready to drop back to 9X4 if needed!
I'm glad that I did this. BTW Saturday morning when I opened my mail box, an OS25LA  and an OS FP 25 fell out!  Both brand new!

[Steve Helmick]

Mail Boxes are a wonderful thing! By the way, that Magnum rear NV assy is about as good as you can get (much better than one from an OS .XX LA), so use 'em if you got 'em!  Steve

[Tim Thompson]

In full disclosure my health has prevented me from flying as much as I'd like. And because of the meds that I take I'm dizzy, but that problem is improving.

Okay back to the OT. With the homemade venturi I was having to fly it with an APC 10X3 put on backward. So I put the carb back on and made a wire to hold the throttle and be able to adjust it. Actually the wire was a paper clip, trombone for our Canadian neighbors. Then I closed the throttle a smidgen and turned the prop back the correct way. Last Tuesday I was able to make 2 enjoyable flights even if they were just round and around and level. I'm going to leave it like this until I can fly better.

[RknRusty]

I used some little colorful rubber hair bands, about 1 cm across. The fuel melted them and my engine swallowed the pantyhose. Luckily there was a bit still hanging out of the gagged engine and I managed to extract it with a pair of hemostats.

[Tim Thompson]

I used some little colorful rubber hair bands, about 1 cm across. The fuel melted them and my engine swallowed the pantyhose. Luckily there was a bit still hanging out of the gagged engine and I managed to extract it with a pair of hemostats.


[/quote

Wow! What kind of fuel were you using? Will it melt rubber bands holding a fuel tank on? The rubber bands that I use are fabric covered.  10% Powermaster does not effect them. Do you have a picture of your fuel melting the rubber bands that you used? It would be interesting to see.

[Steve Helmick]

Neoprene O-rings are commonly used to hold bits of pantyhose onto the venturi. I had my OS .46 VF swallow some pantyhose once, but like Rusty, it pulled out ok with hemostats.     Steve

[RknRusty]

I used some little colorful rubber hair bands, about 1 cm across. The fuel melted them and my engine swallowed the pantyhose. Luckily there was a bit still hanging out of the gagged engine and I managed to extract it with a pair of hemostats.

Wow! What kind of fuel were you using? Will it melt rubber bands holding a fuel tank on? The rubber bands that I use are fabric covered.  10% Powermaster does not effect them. Do you have a picture of your fuel melting the rubber bands that you used? It would be interesting to see.

Sig Champion 10/20.
No it didn't affect the rubber bands securing the tank.
Rusty

[phil c]

Although I  blantely stole ideas from Mr Cartier, ( if you steal ,steal from the best ) I  made all the parts for the plane myself. So yes it did make me feel good! The plane itself flew better than I expected and I just love the motor!

The spacer is in the hardware department at a very well stocker hardware store we have called  Fresno Ag.it's in the section that has special stuff, like nylon,aluminum and stainless steel.  The drawer it was in just said Nylon  Spacers. There is another drawer that says Nylon Standoffs ,but they are smaller. The drawer that has Aluminum Spacers only has them up to one half long.
True Value and OSH  should have the same thing. I always go to Fresno Ag because its my to go to store.

Steal all the ideas you want, Tim.  I first used the plug in wing idea in 1974.  I got it from the Jim Walker baby balsa gliders and a plane from Model Airplane News that used a wing rubber banded on, ala' RC.  I forget where the SC-2 was published.  It made a nice stunt and combat trainer.

If you can find someone who flys, learn to fly loops and figure eights as soon as you can.  Then you won't have to spend so much time just turning around getting dizzy.  If you can't find anyone, look up the little booklet Goldberg included with the Shoestring profile.  It's an easy way to get started by yourself.  The plug in wing usually can take quite a few unintended landing with minor repairs.

[Tim Thompson]

Steal all the ideas you want, Tim.  I first used the plug in wing idea in 1974.  I got it from the Jim Walker baby balsa gliders and a plane from Model Airplane News that used a wing rubber banded on, ala' RC.  I forget where the SC-2 was published.  It made a nice stunt and combat trainer.

If you can find someone who flys, learn to fly loops and figure eights as soon as you can.  Then you won't have to spend so much time just turning around getting dizzy.  If you can't find anyone, look up the little booklet Goldberg included with the Shoestring profile.  It's an easy way to get started by yourself.  The plug in wing usually can take quite a few unintended landing with minor repairs.

Actually I bought plans for both the Plugger and SC-2. I made 3 Pluggers before I had my heart attack. So I gave them away thinking I might not be able to fly again. It's the medications that I have to take that make me dizzy, but I'm slowly overcoming it

Yes I do have several people who are helping me I belong to the club here in Fresno and they are a great bunch of guys. It won't be long now and I'll be able to fly again

[mike holen]

Tim how you doing haven’t seen you in a long time

[Bootlegger]

  Tim, if you have a N A P A , or some other auto parts store get some "O " rings from the air condition section that fit the venturi and they will hold the panty hose filter well and fuel doesn't affect them..

[John Given]

ASP CL venturis can be found here:

http://aerohobby.ca/store/index.php?main_page=product_info&cPath=1&products_id=435