dschmid37

Thanks Arf Guy,
The dummy engine is nothing more than a photograph I found on the internet, glued to piece of 1/16" plywood, then covered in a clear coat.
This baffle, will help the air flow through the cowl much better than having it open.

ARF Guy

Thanks for the info. Good idea with the photo.

ARF GUY

blacksheep

My Feedback: (1)

Since no one else seems to have put the Saito 30 into the Corsair I went ahead with it anyway and today was the maiden "fright".

It didn't seem as fast as my friend's Mustang with the OS 25. Maybe it was just the "mosquito-on-steroids" sound of the two stroke that made it seem faster, but more likely the fact that the 30 FS was not broken in completely or the fuel or the prop size. Which begs the question, just what is the optimum prop size for the Saito 30 when it is to out perform (if it ever will) the OS 25. I used 12% Nitro fuel with significant castor and an APC 10 X 5 prop. I am going to try Wild Cat 20-20 when the engine is ready.

As an aside, the Saito 30 is easy to start and runs reliably, sips fuel, and is great fun. The GP Combat Corsair is a real winner with flight stability and solid maneuvers for a small bird and has an excellent sport scale look. Good job of engineering too. You can't beat the price either.

acep51

My Feedback: (21)

Your plane looks great Blacksheep. I didn't place a Saito30 in mine, but I did install a OS.32SX with a Pitts muffler and Spring Air 600 series retracts. I modified the fix rudder into a functional steerable rudder. I test flew it yesterday and it is a great flying plane! Yes, very stable and no bad tendencies. This plane is also very fast! I beefed up all of the tail structure with 1/32" balsa sheeting and epoxy 45s/fiberglass cloth on the back firewall. Placed 1oz fiberglass cloth on the center wing and outer wing joints.
This plane is very good in all areas and the quality is outstanding.Now, back to my gassers.

ARF Guy

blacksheep, I don't think you'll get a .30 4 stroke to out perform the .25 OS Max. The Saito, great engine that it is, is heavier and does not put out the hp per cubic inch the 2 stroke does. Also, the Mustang is smaller with less wing drag and one less servo to carry. The Corsair also has that big 'speed brake' on the front called an open cowl! My own experience with the Magnum .30 and at 5500' above sea level is that the plane is quick and flies very good BUT videos I've seen of the plane with the 2 strokers shows that mine just isn't as fast. My preference was scale-like flight and not competition, besides, I've seen guys strip out servos with outlandish monster performance stressing the servos and airframe itself in their quest for more speed.

Here in Prescott I'm using 15% fuel and a 10-5 master airscrew. I've noticed some surging during full throttle flight that I cannot duplicate on the ground and I've also noticed residue all around the outside of the FRONT of the cowl. That would indicate that high pressure in the cowl is forcing fuel and oil to blow out the FRONT. I cut a fair sized opening around the head and exhaust but even with the 2 stroke muffler opening I'm beginning to think there isn't enough opening to allow the incoming air to exit smoothly. I discussed this with some old time modelers (well, older than ME) and I believe the build-up of pressure from forward motion is pressurizing the engine compartment. You might think that I'm getting a "turbo-charging" effect however I think the increased pressure fluctuates and causes momentary negative pressure scavenging air FROM the carb intake. It is particularly noticeable when making a quick change in direction. I’m going to enlarge the opening around the head to see if that helps. The baffling that dschmid37 did with his dummy engne maybe the answer but my cowl attachment screws are really hard to get to and I save taking the cowl off as a last resort.

I really enjoy reading how you guys modify your planes and the different ideas expressed.

ARF GUY

blacksheep

My Feedback: (1)

AceP51: Thanks for the Kudos. How much does your Corsair weigh with all the upgrades?

ARF guy: Don't know why you are having the strange fuel dispersion but here is a picture of my engine and cowel cut-outs from the bottom. The opening for the engine head is about 5 cm by 5 cm. There is also some space around that tiny Saito muffler for air to be forced past it and into the cavity that would have been used for the relatively huge two stroke muffler. Notice that there is also a home-brew extension for the muffler pipe made from part of a broken engine.

What RPM are you getting with the 10 x 5 muffler? So far I am turning 10,200 max before takeoff with the 13% Nitro and heavy Castor.

konatiki

Can anyone tell me how they installed there landing gear and steerable tail wheel? Maybe a picture or two. I guess the way I would do the tail wheel would be to find where the leading edge of the rudder would be on the top of the fues then drill a hole all the way thru the fues (top to bottom) then use a tail wheel setup with the rod going into the rudder with an L bend, but I have no idea on the main gear.

ARF Guy

Yeah, your opening is somewhat larger than mine.

I'm getting up to 10,500 on the ground but I back it off per Magnum's recommendation to about 10,000. RPM range is up to 12,000 (but they don't say what prop) and here in thinner air I worry about over-revving in flight. 12,000 RPM's seems a lot for a pushrod 4 stroke. I guess I shouldn't worry. If you watch the ads you can get the Magnum .30 4 stroke for a hundred bucks.

Early in its life I had a couple lean runs where the engine quit. Before I put it in the Corsair I pulled the head to look for heat damage and it looked like it hadn't been run, not even any discoloration on the top of the piston. Darn thing starts almost instantly and even in 20+ degree weather like we had a couple days ago. I've heard of folks running high nitro (20% or more) for improved reliability. Have you or anyone else run 4 strokes on high nitro fuels and if so any problems, damage or shortened life?

Thanks,

ARF GUY

dschmid37

Arf Guy, everything I've ever read or been told about air flow through the cowl, is for every square inch of incoming air, you should have 2 square inches of exit openings.
The huge open cowl on this corsair causes a buffeting of air which hinders cooling for sure, and it wouldn't surprise me if it is causing some pressure problems with your carburetor. Having a smaller opening created with a baffle and in line with the engine head, will cause a rush of air (venturi effect) right where you want it for cooling.

Dan/dschmid37

dschmid37

konatiki
The placement of the rudder on this aircraft makes it very challenging to incorporate a "steerable" tailwheel. I am using a castoring tail wheel which causes
you to make your rudder actually functional so you can steer. That is easy on this model. Great Planes has even included the hardware for this. You can see some pictures of
what I've done for landing gear in my gallery. I must warn you, this gear has not been field tested because.... WE HAVE SNOW!!!![:@]

Dan/dschmid37

ARF Guy

I believe you are correct Dan. I'll be working on it.!

ARF GUY

ARF Guy

dschmid,

Found a pretty good head on shot of a P&W 2800 radial used in the Corsair. I printed it out and glued it to some thin plastic then clear-coated it. I cut out the area in front of the cylinder and hope to try it out today. Thanks for the suggestion.

ARF GUY

dschmid37

Excellent, let me know how it works and if that solves your problem.

ARF Guy

Well, outside of the fact that the temp was in the high 20's, the baffle seems to work. When it's this cool, I let the engine warm up completely before I tune for maximum power. When I adjusted the high end it was tacking over 11,000 rpms and running solid in any attitude. I took it off and after a couple circuits I tossed it around pretty good without the engine bogging as before. I pulled into a loop and was able to make the largest one it ever did with good power all though the manuver. I landed and checked the engine temp and it seemed very good. A subsequent run on the ground showed that the baffle will rotate in the direction of the engine run and overheat the engine so I've got to secure it. I think I'll run a scew through the baffle and into the front of the motor mount thus giving the the ability to release it and move the air intake slot around for access to cowl attachments screws and low speed needle ajustments.

Thanks for the idea. It made an already enjoyable plane just that much more fun. It is definiately something anyone who buys the Corsair to keepin mind.

ARF GUY

finishman2000

My Feedback: (7)

well i flew my corsair this morning....25 degrees and 10" of snow on the ground but I had to try it out. Flew very nice and hand launched no problem. The mustang seems faster and more agile but the corsair looks better coming in on the deck (to me anyway). Great little planes and very cool belly flopping in the snow!

dschmid37

Arf Guy,
Your welcome, I'm glad it worked for you.
I had a couple of 6-32 blind nuts laying around so I put those through my baffle and fastened it to the front
of the cowl itself. I hope the cowl can take the pressure around the screws. I think I'll beef it up on the
inside just in case. You're right, you have to be able to spin it around to get to the cowl attachment screws.
On another note, have you tried the Sonic Combat Module for your Stryker? It is loads of fun shooting
another combat module equipped plane down. I found a guy who makes a converter for this module so you
can use it with any receiver! When it is used in a gas plane, it is connected to the throttle servo, and when
you get "hit", your throttle will open and close erratically. (like you have engine trouble) If you reduce the
throttle below halfway, your engine will run smoothly so you can maintain control without endagering anybody.
If you try to throttle up above half, it will again run erratically. This only lasts for about 10 seconds and
then you're ready for another dogfight. I just bought 2 of them. One will go into the corsair, and I must talk one of my
fellow club members into buying a "Zero"!
Here is the link to these babies. They're very small and light!
Talk to you later, Dschmid37

http://www.rcgroups.com/forums/showthread.php?t=129958

ARF Guy

DS,

The only other Stryker owner in the club seldom flies it so not much dog-fighting here. Sounds like you use every aspect of the hobby.

Enjoy,

ARF Guy

ARF Guy

Here's a close-up of the baffle and cut out in the cowl of my Corsair. It was good for 500 RPMS and good stable engine runs.

babenson

OK Gang I set up my retracts over the weekend and a usable rudder. Only problem I have now is that I already glued the vertical stab in place and cannot figure out how to make it steerable. Any suggestions? Also, I will post some pixs tonight of my landing gear with brief descriptors. I am not sure how much I should bend the gear wires forward though. Any suggestions?


BTW
I am talking about the Corsair.

smokingwreckage

babenson,

The main gear axles should be even with the leading edge on a taildragger, with the aircraft in its normal level flight attitude.

Lewisville, TX, eh? I'm 40 miles west in Alliance. Do you know of any other LHSs besides Aero Hobbies or Mike's between I-35 and I-35?

smokingwreckage

Has anyone radared the Mustang with a stock OS .25FX?

ARF Guy

babensen, just make it a caster. There IS no easy way to make it steerable unless you spend a bunch of time and effort trying it run another pushrod down through the bottom and attach a bellcrank to the tail wheel. Isn't worth the time or effort. My caster works fine unless there is a cross wind. Just give the rudder plenty of throw and I've found that on a dirt runway it is more effective if you do not hold up elevator when taxiing. Mine has the axles even with the leading edge with a touch of toe-in. Tracks straight and true. On the real Corsair the gear are right behind the leading edge and appear to go straight down. In RC world we can give ourselves a little advantage!

You have rotating retracts that small? Sounds neat, please include picture in your next post!

Thanks, ARF Guy

Clean

Just use the spectro-analysis program found on this website http://www.philsrcworld.fsnet.co.uk/speed.htm

No need to go find a radar gun and try to stand in the path of a missle to get an accurate reading from the gun. You only need a sound recorder and the required cable to play it into your computer.

smokingwreckage

Clean,

That looks like a neat little program. I don't know how accurate it would be, but should give some idea of how mods affect speed. Somebody want to Dopplar their Mustang with a stock .25 sport engine for me?

We have a club member who is a state trooper. He stops by the field occasionally and uses the laser in his cruiser to get speeds. It is very accurate. Range is sufficient that he can stop on the road a couple hundred yards from the pylon and still get good readings.

cochinito77

hello! for all the people that have the coconuts to fly this with a .46 fx or any humongous engine [X(] .
do you all have any issues with it torque rolling when you take off? do you handlaunch or standard take off? and if so do you do it on grass or paved?
i was just wondering because i have a spare .46fx lying around along with $99.99 thanks fellas-
Rafael