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Old Feb 19, 2004, 10:56 PM
check your six!!!
rc.hackmaster's Avatar
maltby washington
Joined Mar 2002
31 Posts
what prop are you using? if it has a lot of pitch you wont get alot of r's. mine on a 13x8 gets just over 9 grand. more pitch=less rpm's and more speed. try using a 13x6 and read the tuning section in the manual. you should get a nice smoke trail with a blue sky background . btw my engine is only a 65. try setting it for the 8000 mark and try flying. it should fly fine. the 72 is a torker you dont really need alot of rpm's. our feild manager told me once that alot of guys try to squeeze as much as they can out of a 4 stroke thinking in 2 stroke. it just doesnt work like that. its all about torque. thats why i like 4stroke power big prop and low rpms. as long as you have the idle mixture set properly you shouln't dead stick. just in case you do the mentor does glide pretty well. and be easy on the new engine for at least a gallon of fuel. what fuel? i hope you use at least 15%. if you want alot of power try using 30% heli fuel, it'll run killer and have gobs of power. but dont try till you go thru a gallon first or regular fuel. more nitro will kill it quicker. let me know what happens. hack.
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Old Feb 19, 2004, 11:35 PM
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Joined Jan 2004
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Quote:
Originally posted by rc.hackmaster
what prop are you using? if it has a lot of pitch you wont get alot of r's. mine on a 13x8 gets just over 9 grand. more pitch=less rpm's and more speed. try using a 13x6 and read the tuning section in the manual. you should get a nice smoke trail with a blue sky background . btw my engine is only a 65. try setting it for the 8000 mark and try flying. it should fly fine. the 72 is a torker you dont really need alot of rpm's. our feild manager told me once that alot of guys try to squeeze as much as they can out of a 4 stroke thinking in 2 stroke. it just doesnt work like that. its all about torque. thats why i like 4stroke power big prop and low rpms. as long as you have the idle mixture set properly you shouln't dead stick. just in case you do the mentor does glide pretty well. and be easy on the new engine for at least a gallon of fuel. what fuel? i hope you use at least 15%. if you want alot of power try using 30% heli fuel, it'll run killer and have gobs of power. but dont try till you go thru a gallon first or regular fuel. more nitro will kill it quicker. let me know what happens. hack.
I'm using a 13x8 prop. I wish the book was more specific about setting the rpm or gave some forumula to figure out rpm for what prop you are using. I was looking for around 9,500 to 10,000 so when I could only hit 8500 I was a bit concerned. I dont use need for tach if I dont know what max rpm to expect in the first place.

When you say 2 turns, are you saying that from 2 1/2 I should be able to turn in approximately 2 turns? I hope thats not the case because from what I could tell the engine stops showing any improvement on rpm after I turn in about 1/2 turn, which would be equal to two turns open.

I think I made a mistake getting the four stroke. 2 strokes are so much easier to set by ear and like I said, what use is the tach if I dont have a base rpm to start from for the prop I'm using? Im taking it back to hobby town tomorrow so they can check it out. Besides the 8000 rpm issue, I found that after setting the needle to where I thought was optimal from listening, the engine does not maintain a steady tone. You can hear the tone raise and lower in short subtle surges. Now I have to wonder if the engine has been damaged because I was going by the books instructions and trying to reach a higher rpm.
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Old Feb 24, 2004, 08:02 PM
check your six!!!
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maltby washington
Joined Mar 2002
31 Posts
dont give up on the 4 stroke yet. i talked to a couple of guys at the club who are 4 strokers. set for about 8500 to 9000 rpms on the ground it will go to the max rpm in flight, on the ground you are getting static thrust, in flight there isnt much resistance from the air. so the engine doesnt work as hard, and it will achive the max rpm for the needle setting. but dont set too lean or youll detonate the engine and that will do nothing good to the engine. allways set rich. ok i just read the saito manual and they have the peak rpms wrong for static tuning. open top mixture screw 2 1/2 turns and start. warm up and then check max rpms, try to set it for 8500 to 9000 rpms. you may need to open (richen)the top end a little or you may need to close (lean) the top end to achive proper rpm range. if you hear some loud popping or banging at max rpms in flight such as in a dive on a fly by, then your a little lean on the top end. it should sound clean and be pretty quiet. sorry if i didnt answer your question the first time. your engine should be ok , just try retuning and set for the rpm range i gave you and it should run great. be patient and give the engine a chance. i also have 2 strokes, they are good for sport planes but you cant beat the 4 stroke sound in a scale plane, its just an awesome thing to see and hear. if you want to try to call me for better explanation pm me. the hack....
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Old Feb 24, 2004, 10:11 PM
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Joined Jan 2004
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Getting engine back in next day or two

You information is always helpful and welcome. I took the engine back to hobbytown and the owner took it to an older experienced club member that is known for his knowledge of 4 strokes. He got it running correctly and said the valves were not correct from the factory. They say its running very smooth. Im going to pick it up in the next couple of days. Weather is bad so there is no real hurry. Of course I got a new spinner. Went from black plastic to aluminum. Had to get an adapter to make it work so its going to add more weight to the front so that means more weight to the back to balance it out. After a few flights and I am comfortable with it, Im going to get the retracts.
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Old Feb 24, 2004, 11:25 PM
I can 3 point
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Mount Dora Florida
Joined Aug 2002
731 Posts
Hi Widowmaker,
perhaps I should have jumped in a little earlier, I didn't see the way the thread had gone until today.
Even if I knew the kind of fuel you were using and content plus the prop size and where you were running the engine and how you mounted it and what tank you had and where the tank was and what type of tubing and etc. etc. then it would still be difficult to tell you what rpms to expect. I am not trying to be funny just to point out the many things that peak rpm depends on, the manufacturers cannot give an exact number withoput taking the chance of having people burn their engine out or being so conservative as to make some combinations unusable. I will go out on a limb and say with a 13x8 on 15% fuel you can expect about a 9400 peak from others (not mine)experiences, you would back off about 300 and run at 9100 if that is right. Having said that. I did my buddies and I think we had it about there (8900-9200) with 15% wildcat here in Florida.
To be honest I wouldn't think of trying to set a four stroke by ear without a lot of experience, I don't, definitely not for top performance and longevity. The tach is the only way to go. The difference in sound between a few hundred rpms is less easy to hear with the 4c.
The thing is that you tune a 4c the same as a 2c. Warm up the engine set rich, open throttle wide and close the needle gradually letting the engine settle between turns until you find the peak rpm, then back off a couple of hundred rpm. Then you set the bottom end. The only difference with the 4c is that you use the tach to determine peak rpm's and not your ear ( it doesn't hurt to use the tach with a 2c either as it is more accurate).
I will say this, the first 4c I had was a saito 56, it was new to me and I had help tuning it from many experienced flyers. It was very inconsistent and unreliable. I found that I had let so many people mess with it that really had just a little more knowlege than I did and that was foolish. I called Saito and asked how to get the needles back to the factory settings and followed the instructions using a tach. Everything went great, it still had a few problems so I took the cowl off and noticed some bubbles coming in with the fuel, I balanced the prop as someone told me it could be vibration but no luck. Then I did some research and checked the length of the clunk in my tank, it was not touching the back but was close, maybe 1/4 inch, I took another 1/2 inch off and my bubble problems ended. Did a final tune by the book and the engine ran like a top all the way to 4 inches underground some time later when my ego overtook my flying skills. Since that time I have only bought one 2c, all my glow planes have 4c engines, (ys or Saito) and I couldn't be happier.
If you cannot get a fairly constant rpm after balancing your prop then check your fuel feed, tank position and muffler pressure.
Look for bubbles in your fuel line etc. Check your valves as if you have run it a little fast and you have a little fuel through it it will be ready for its first adjustment.
If you like I will post a complete run down of tuning the Saito including the bottom end, use the tach is the best advice I can give, the fuel economy,sound and flying character for a warbird I am sure will make you a 4c convert.
good luck
Paul
whoops, typed this while you weere posting the last one, glad you are sorted out.
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Last edited by Paul Wilson; Feb 24, 2004 at 11:29 PM.
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Old Mar 22, 2004, 10:54 PM
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Joined Jan 2004
67 Posts
Maiden Flight

Believe it or not I took the mentor up for the first time yesterday and two more times today. I was waiting on my AMA and joined the local club. I give this ARF two thumbs up on flight. Its stable and looks very good in flight. The retracts really touch it off. The Saito seems to be running ok. In the process of waiting on my AMA I got the H9 Funtana S40 ARF and another Saito 72 and a flight pack. I took it up yesterday and today as well. Roll rate from hell even with the aileron throw 1" less than suggested. This ARF was alot easier to get ready since the wing is in one piece. The covering was perfect. Its also very stable and floats in for landings. The mentor does very well at low speeds but weighing almost twice as much it does not come in as slow.

Thanks for everyones help and input.

Lots of plane pics at http://www.pbase.com/rz22g
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Old Mar 26, 2004, 04:28 PM
Ice
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United States, CA, El Cajon
Joined Jul 2002
578 Posts
I have one and getting ready to maiden her out this weekend.. cg is from root AGAINST fuselage not typical leading edge.. please confirm...
Nickel
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Old Mar 26, 2004, 11:01 PM
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Quote:
Originally posted by Ice
I have one and getting ready to maiden her out this weekend.. cg is from root AGAINST fuselage not typical leading edge.. please confirm...
Nickel
I attached the wing and measured from the leading edge of the wing right against both side of the fuselage. Thats the way I took the instructions to mean. Either way it worked out great. Very stable even at low speed. Its a joy to land.
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Old Mar 29, 2004, 11:49 AM
Ice
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United States, CA, El Cajon
Joined Jul 2002
578 Posts
thats what I did, thank you sir
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Old Aug 11, 2004, 04:21 PM
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Joined Aug 2004
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mentor engine? four stoke size?

Can I put a 4 stroke 90 on a t-34 mentor? the largest it calls for is a .72.
hangar 9 .40-.46 size arf.
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Old Aug 11, 2004, 04:49 PM
Ice
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Joined Jul 2002
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It will be hard to fit in the cowling my 72 does and it has enough guts..otherwise sure
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Old Jun 06, 2005, 01:49 PM
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Joined Jun 2005
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how does this airplane fly? is it more aerobatic than a basic trainer?
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Old Jun 06, 2005, 02:32 PM
Ice
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if you consider aerobatic as is real airplanes. Yes very much so... I dont consider 3d or 4d flying airplanes... maybe cause I am a pilot.

I highly recommend her as great fun for any occasion.
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Old Jun 10, 2005, 11:34 PM
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Dallas Texas
Joined Feb 2003
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My T-34

I have the Hangar 9 T-34 arf.
I did a few mods but not much.
I drilled out the retracts and installed a larger wire. (mains only)

I had a old set of wheel well liners painted them and glued them in.
While doing gear I made a set of outer gear doors, just some scrap plastic.
.
As for the wing I do not like those servos hanging out in the breeze.
I purchased some servo covers from Hobby Lobby made them flush and painted those also, much cleaner look on the underside.
For the noise maker I had a trusty OS 46 SF engine plopped it in and a Graupner 11X6 2 blade prop. perfect fit and power.

I did not like the plastic wing walk and the glare shield so I removed it and painted it flat black
Decals looked too skinney to me changed them out for a set I had for another plane.
The rest of the plane was mostly box stock as per the instructions.

As for flying it does it all fast slow and everything else in between.
You do need to get the plane slowed up to land wants to come in fast.
I slow it down early and get that slightly nose high look for landing.
I would build another one if I needed to.
I haveoinly flown it on a paved surface, grass is unknown
Two thumbs up here
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Old Jun 21, 2005, 10:27 PM
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Joined Jun 2005
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For fuelproofing, I like to use Aerogloss / Dope. It's meant more for silk covering etc, but as long as you get the fuel-proof kind it works pretty good on all the woods you would normally use thinned epoxy on. Plus you can get your innards to match your plane's exterior. Or for the T-34, I used gray on the wheel wells and all visible wood near the firewall. Makes it look like real internal metal!

My issue though is the fuel tank on the Hangar 9 Mentor. It barely fits, and even with thin foam, it's so tight in there I have to think that it's going to vibrate right through the compressed foam and foam up the fuel. What have others done about this? The only way it goes in is if I make sure the fuel cap goes into the large center hole in the firewall. Then the back just clears the instrument panel's wall. So there's really not a lot of options for giving it more room short of buying a different tank. Eeek. I can make the firewall hole bigger and maybe sand the panel at the back of the tank but that's about it. Otherwise, I'll just run a few tanks of fuel through it and see if I can spot any fuel problems. I really want to fly this bird this weekend!
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