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quote:
ORIGINAL: Airbike-RCU
Ended up using a 8.8 x 8.75 clipped to 7.8 dia. Engine was at about 19100 on the ground.
I would have figured that RPM with out clipping the prop down that far. I was able to get about 18,100 with a Jett 50/SS muffler combo and a APC 9x8. Load factor on a 9x8 is 52488 and the 7.8x8.75 is 32388.
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Joined: 6/25/2004 From: Merced, Ca., CA, USA Status: offline
AIRBIKE:
Just knew you had the stuff to make this go right. Wonder if flaperons would improve my Krangke F-3d landing ability? ( or mine). The next question to answer is turning. You indicate it looks ok so far, should be ok, but as you know, strange stuff happens when you are going fast. Blew a elevon off a Q-500 a few weeks ago. Lawn dart? Nope, the thing did a very tight slow spin into the ground, did not even break a prop. Forces were such it fuse cracked all over the place, but it came down in on piece and did not even get dirt in the Jett 50. Deserve a little luck once in a while! Keep us informed please!
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Joined: 2/21/2004 From: Benicia,
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Looks like you still have issues with the engine muffler combo. A q40 engine would have supplied a lot more power even with the carb you are using. Good luck and have fun flying that beast.
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Joined: 3/18/2003 From: Walnut,
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Well, had a couple more flights today. and a close call too... Got it too far away preping for a landing and thinking about spoilerons or flaperons and the silloeutte almost went the wrong way. I'd better try harder to keep it closer.
Tried some pylon type laps and they were pretty groovy, turns were pretty tight without any problems.
I still have to figure out the sweet spot for the landing flare. So far the flaperons slow it down well but the flare has to be JUST RIGHT, or it goes bouncing down the runway. No broken props yet (I usually kill the engine once I'm over the threshold) but there must be some landing tips you speed guys can give a speed newbie.
Bob, I've got a question about the Jett. I've broken in the engine for about 30 to 40 minutes on the bench and it runs great. Once mounted on the plane. I've noticed the exhaust to be somewhat black mixed in with the oil. Should I be concerned with this? The engine is only warm to the touch after I land. Powermaster 15% fuel.
Mike, during the bench break-in, I ran the 8.8x8.75 on the 6th tank and it peaked at about 19400, but the engine seemed to run much hotter than before, so I clipped the prop to reduce the load. The ground rpm of 19100 or so was not the peak, that's just where I stopped leaning out the needle. I don't know how much these things unload in the air. Is it around 1K? more...less?? I figured that it would be safer if I didn't go for max performance until I get more time on the engine.
Opps, forgot the sunny pic:
< Message edited by Airbike-RCU -- 11/13/2005 4:32:35 AM >
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Posts: 4712
Joined: 4/9/2002 From: Cleveland,
OH, USA Status: online
quote:
ORIGINAL: Airbike-RCU
Bob, I've got a question about the Jett. I've broken in the engine for about 30 to 40 minutes on the bench and it runs great. Once mounted on the plane. I've noticed the exhaust to be somewhat black mixed in with the oil. Should I be concerned with this? The engine is only warm to the touch after I land. Powermaster 15% fuel.
Regular burnt fuel residue is normal .Dark brown - dark amber in color is normal and is ok.
If you are seeing acutal black, metalic coming from the engine, that is not right.
Make sure the head bolts are tight. Make sure the muffler is secure. Make sure nothing on the engine is rubbing on the airframe.
Put the bigger prop on it too. The small prop may be causing the engine to run too cool. If it runs too cool, the cylinder/piston fit is too tight (might be the black you are seeing). The 8.8x8.75 at 19,400 peak is perfect - back that off 500-600 rpm and fly it. A smaller prop hitting mid 19K range is hitting 'the governor' of sorts - its only going to turn up what the muffler allows it to. The only prop you might want to cut down is the 8.8x9.25.
If you feel you continue to see 'black metal' in the exhaust residue - let me know.
Bob
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Joined: 1/10/2002 From: Tulsa, OK, USA Status: offline
quote:
ORIGINAL: Airbike-RCU
Mike, during the bench break-in, I ran the 8.8x8.75 on the 6th tank and it peaked at about 19400, but the engine seemed to run much hotter than before, so I clipped the prop to reduce the load. The ground rpm of 19100 or so was not the peak, that's just where I stopped leaning out the needle. I don't know how much these things unload in the air. Is it around 1K? more...less?? I figured that it would be safer if I didn't go for max performance until I get more time on the engine.
It sounds like Bob answered most of the questions. I always understood this engine would unload 1.5k+ if tuned right. Maybe Bob can varify that.
I also noticed very dark (almost black) exhaust sometimes on my Jett 46 and 50. The muffler was tight so it concerned be for awhile but a couple hundred flights later the engines were still good. I pushed mine to the limit and got a little lean sometimes but these tough engines left the energizer bunny in the dust. I am sure they could be fried but mine never did and let me just have fun without being too careful.
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Joined: 6/25/2004 From: Merced, Ca., CA, USA Status: offline
Yo Bob Brazil:
Please see "My Way's" comments regarding a Q-40 being more powerfull than the Sport Jett 50. Thats not what I understand, but must ask you for a rulling. Not that I don't respect My Way's knowledge, but still want your comment for future design purposes.
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quote:
ORIGINAL: rmenke
Yo Bob Brazil:
Please see "My Way's" comments regarding a Q-40 being more powerfull than the Sport Jett 50. Thats not what I understand, but must ask you for a rulling. Not that I don't respect My Way's knowledge, but still want your comment for future design purposes.
Yeah, the QM40 engine probably is a bit more powerful. Short of an FAI engine, its pretty much squeezing every last bit of power that one might be able to obtaion from an 6.5cc (.40) engine. Develops on the 'order' of 3 hp. Runs well at anywhere between 23,000 and 27,000 rpm with a 7.5x8 prop on it. Will not run lower power for any length of time. Putting an red-jett carb on it is somewhat useless. The QM engine has a huge inlet venturi, monster timing and porting in the cranskshaft, and rather critical cylinder ports and port timing. If you were to throttle back, its just going to shut off (we use to run the q500 carbs on them for a while). Selecting the correct prop for a particular day, and setting the needle before each flight is somewhat of a learned science.
The QM40 engine is by no means a sport engine. But it is big power.
However .... the QJ-40 428 engine is more compairable. The SJ-50 or SJ-60L can perform like the Q-500 engine with the right setup.
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I have a Krangke F-3D gathering dust and sut in my garage just waiting for assembly to resume. I couldn't believe how stiff the aileron hinging was. I could just see my servo's burning down trying to deflect those buggers. I don't want to slam dunk it into somone's crainium whlie triming it out on the 1st flight. Since many of you have one (or had one before your servos melted down) perhaps you can enlighten me with a bit of confidence and say that is the way it should be. Also, what mutha brute force servos are you using?
I have a LR-1 also. Hard to believe anyone (especially the mfgr) would recommend or even suggest that the L/G be mounted foreward of the wing mount. They took an already ugly L/G and really made it look like someone from Walmart was doing their design work. Heck, even the Q500's don't use an 8oz tank, but this undersized 1/4 midget .15 plane does. Duh.....why? Got a few tricked out engines to try in it...... .8 thru .32. Originally was going to stick my Cyclon .15 in it to keep the weight down and RPM's up .....all 35000 of them without a pipe.
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Joined: 6/25/2004 From: Merced, Ca., CA, USA Status: offline
Twitcher: Know what you mean. I bought a couple of JR mini high torque digitals for mine for the same reason. No apparent problems in flight. I hand flexed mine for a while until some of the stiffness came out. Remember, there are two of them. My Yellow Jacket ailerons were a problem as the wing came off a Q-500 and the torque rods were sloppy. Solved the problem with some CA, but created a little movement problem. Fixed it with a JR 8611, works great, good centering etc. and has, through use, worked itself in. Oh yea, the servo is 280 oz. ENJOY Rever Bro 119
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Joined: 7/7/2005 From: , TX, USA Status: offline
The LR-1 flies good, lands bad. Flaperons work, but swept back landing gear work better. My club flies a .25 sport engine class with no mods allowed. I use a GMS .25 with an APC 8.7-7 pylon prop cut to 7.7, and see 16,220 on the ground. My landing gear is custom carbon fiber, hand laid and vacuum bagged, with pants over Dave Brown 1 1/2-inch wheels. The plane tops out at 106mph. Pretty good for a stock .25. I've not had any problems landing my LR-1, but everyone else who has tried to land on our grass field has destroyed theirs. I think the flaperons and modified landing gear make the difference because my landing speeds are easily 15-20mph less than anyone else's. Moral of the story: rework the landing gear and add flaperons before attempting to fly the LR-1.
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RE: wild hare, LR-1 pylon racer - 
