Super Chipmunk Engine Upgrade

Here is the story.

On Sunday I went up to Cashmoor with the Super Chipmunk which was fitted with an ASP180 FS. I have had this model for a number years and tried numerous props. Prior to Sundays outing (there was only three of us there ) I had tried a Menz wood 17x10. It did not like it at all, started to overheat. Rummaged in the prop store and found a "club" of a prop. MS Classic 18x6. Go for it! I raised the compression ratio a little by removing one head shim and did a quick home test. Well it swings it okay and a lot of air moving. Really need to WOT it up at Cashmoor with the tacho on it.

Before it never went above 7900 with a lighter loading prop. Now it was giving 8500 peak with the lawn mower blade from MS. As Chris H said fly it and see. Sounds like a real plane, slightly faster but above 2/3 throttle a real bark begins but not much more agility. Back on the ground tweaked it again with a slightly richer mixture and played with the throttle curve. Fly it again, slightly better. But not much! Flys around at half throttle easily and relatively quiet. An afternoon of p***ing about and covered in oil plus little time with the Angel which was getting bounced around a bit in the gusty NWesterly, then came the rain.

Driving home I thought, b*gger it, i have had this model for at least 3 years and never been happy with the performance even for a 13 pound scale model. It's gonna get a 30cc/35cc gasser. So today Monday pulled the ASP out, re-plumbing 600cc tank for petrol, removing the anti-vibration mounting. Test fitting a DLE 35 RA as a dummy engine on to the firewall looks like I will have to fill in some of those original mounting holes.

Finally plumped for a OS GT33 and ordered it today. Going to use DLE30 stand-offs (ex Ebay) Chippy looks rather forlorn now but while it is at this stage I will tidy up the covering and work on the new cowl locating screws positions.

Nice one.Phil, can't beat a gasser

flyingpete wrote: Nice one.Phil, can't beat a gasser

A sort of "trial run" for the Pepsi too .......

Due to rain and some DIY to undertake was unable to work on the Chippy's firewall. However, have replumbed the original 600cc tank for petrol. TNT delivered the OS GT33 this afternoon. Had to take a good look over the motor. Machined surfaces are superb nearing a mirror finish unlike DLE although I am knocking DLE as such.

As the future days (weeks) look like mini hurricanes mingled with wet stuff, which will put flying out of the question, I will share the DIY time :lol: with sorting out the firewall so I can mount the engine. Rummaging through my parts stores I have found an Opto Kill switch, breather outlet and heavy duty switch. Planning on using LiFe direct power for all electronics.

As the OS GT33 is a little lighter than the ASP 180 FS I may be able to bring hardware forward. We will see.

A question although I cannot see any reason why not. Is there any issue with mounting a Dubro tank inverted? It's the type with the recessed front. To me it just means that the outlets are at the bottom. I really would prefer it that way so access to the plumbing is easier to work on and maintain.

Plus when the tank is low in fuel the clunk would be in the small area therefore more depth of fuel.

PhilF51 wrote: A question although I cannot see any reason why not. Is there any issue with mounting a Dubro tank inverted? It's the type with the recessed front. To me it just means that the outlets are at the bottom. I really would prefer it that way so access to the plumbing is easier to work on and maintain.

Plus when the tank is low in fuel the clunk would be in the small area therefore more depth of fuel.

p

Phil - I used a Dubro tank in a Galaxy " Mystic" powered by a Laser 150, as long as the filler & breather pipes are angled
to the top of the tank ( in fitted position ) cannot see any problem, Never had any fuel problems when flying inverted
Colin