C-ARF Ultra Flash build Thread + Video
03-31-2016, 11:15 PM
#5051
Hey SR117,
Not to distract from a thread on the Flash, but to answer your question on the Scorpion: I absolutely love it. no vices, goes slow very well. don't expect it to go very fast (unlike the Flash), véry draggy airframe, thick wing, and the way the inlets are designed make it slower as well. Mine is from the earlier production, so finish is not top, but the newer production is much better finished. Also, because the main gear is in the fuse and not on the wings, it can take an enormous amount of abuse. Mine is the "medium", powered by a 15kg Graupner Booster. on takeoff, it accelerates like it's been bitten in the a**.....I mostly cruise around at half throttle.. On landings I lower the gear and set half flaps on the base leg, full flaps on turn to final, and then I pull the airbrake on final.... glides in nose high, and on a long field you can do wheelies forever. just make sure you have enough throw on the elevators to flare, as the flaps mask part of the elevator when full down. This apparently is much less the case on the big Scorpion.
Dub, thx for the feedback... I would also like to set it up like with the saddle tanks for fuel... I'd have to see the original tanks first of course, but the jet-tech tanks seem a very nice addition.....
Dave, I think it's mostly my eyes.... ;-)
Wim
Not to distract from a thread on the Flash, but to answer your question on the Scorpion: I absolutely love it. no vices, goes slow very well. don't expect it to go very fast (unlike the Flash), véry draggy airframe, thick wing, and the way the inlets are designed make it slower as well. Mine is from the earlier production, so finish is not top, but the newer production is much better finished. Also, because the main gear is in the fuse and not on the wings, it can take an enormous amount of abuse. Mine is the "medium", powered by a 15kg Graupner Booster. on takeoff, it accelerates like it's been bitten in the a**.....I mostly cruise around at half throttle.. On landings I lower the gear and set half flaps on the base leg, full flaps on turn to final, and then I pull the airbrake on final.... glides in nose high, and on a long field you can do wheelies forever. just make sure you have enough throw on the elevators to flare, as the flaps mask part of the elevator when full down. This apparently is much less the case on the big Scorpion.
Dub, thx for the feedback... I would also like to set it up like with the saddle tanks for fuel... I'd have to see the original tanks first of course, but the jet-tech tanks seem a very nice addition.....
Dave, I think it's mostly my eyes.... ;-)
Wim
04-05-2016, 04:21 PM
#5054
New UF test flight. Well it flew. Very little trim required. Accelerates like a rocket. The only issues are it snapped out of a split S and drops a wing on landing. I think the cg is most likely a little too forward. I moved the batteries back a little but didnt get a chance to fly again. Any ideas about a forward cg causing the snap and wing drop?
04-06-2016, 12:38 AM
#5057
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New UF test flight. Well it flew. Very little trim required. Accelerates like a rocket. The only issues are it snapped out of a split S and drops a wing on landing. I think the cg is most likely a little too forward. I moved the batteries back a little but didnt get a chance to fly again. Any ideas about a forward cg causing the snap and wing drop?
Azzam
04-06-2016, 06:37 AM
#5058
My Feedback: (51)
New UF test flight. Well it flew. Very little trim required. Accelerates like a rocket. The only issues are it snapped out of a split S and drops a wing on landing. I think the cg is most likely a little too forward. I moved the batteries back a little but didnt get a chance to fly again. Any ideas about a forward cg causing the snap and wing drop?
sounds like rear CG.
04-06-2016, 09:11 AM
#5059
My Feedback: (57)
New UF test flight. Well it flew. Very little trim required. Accelerates like a rocket. The only issues are it snapped out of a split S and drops a wing on landing. I think the cg is most likely a little too forward. I moved the batteries back a little but didnt get a chance to fly again. Any ideas about a forward cg causing the snap and wing drop?
Good luck, Jay
04-06-2016, 11:39 AM
#5061
Thread Starter
222 is still nose heavy for most people, the sweet spot for many is 225-230mm. depends how your balancing it too...I'd never trust an electronic gimmick 
Still say the UF does not need CROW, test flown a few more in the last couple of months and they land sweetly and predictably-you can hold them off nicely.
Trouble is there is such a variation in flying weights and conditions we fly in on a international forum.
Still say the UF does not need CROW, test flown a few more in the last couple of months and they land sweetly and predictably-you can hold them off nicely.
Trouble is there is such a variation in flying weights and conditions we fly in on a international forum.
04-06-2016, 10:42 PM
#5063
Thread Starter
Gear up/down, if the balance was that critical we would be in trouble. Since its the landing phase people are concerned about and usually the gear is down to land...i'd balance it like that ;-)
04-06-2016, 10:51 PM
#5064
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). I put the crow mix on a switch for when I need it. Happy flying.Azzam
04-07-2016, 02:41 AM
#5066
Thanks for all the feedback and ideas. I have been doing this model thing for over 50 years and still learn from smart guys around the world. I had originally balanced gear down as that was what I was taught. I was surprised by the change in cg with the gear up/down. The test flights went well except for the snap/roll off but I was a bit surprised by the amount of trim required after the gear was down. I have Electron retracts and they are pretty "hefty" which causes a lot of weight to swing around during retraction/extension. I was taught many years ago by some guys who had been flying models over 50 years...(yeah, I know that makes me an official "old fart") Nose heavy airplanes fly poorly - tail heavy airplanes fly once. They also taught me that a airplane that is excessively nose heavy is prone to snapping out of a loop and dropping a wing during landing. I have been studying this very subject on the SkyMaster F-4 (my next project). Nose heavy jets have lots of problems such as long takeoff rolls then jumping off the ground during takeoff, diving with flaps and other nasty things. The guys who have the balls to move the cg back have now found the jet flys best with the cg 50 - 90 mm back from the original manufactures recommendation. BV recommended cg's for his products are slightly nose heavy. He does this to help ensure success on the test flights which allows us to move the cg back to one which is comfortable for the pilot. (See my previous statement on nose vs. tail heaviness). I have really been careful on this Flash..even with all my experience I have dorked 2. The first one on the 4th flight (which I believe was too nose heavy as it rolled off on landing just like this one) and #2 which I just plain "dumb thumbed". I'll give an update after I fly again on Sunday, 20-30 kt winds forecast in South Carolina for the next 2-3 days.
Last edited by tp777fo; 04-07-2016 at 03:59 AM.
04-07-2016, 03:20 AM
#5067
My Feedback: (57)
Thanks for all the feedback and ideas. I have been doing this model thing for over 50 years and still learn from smart guys around the world. I had originally balanced gear up as that was what I was taught. I was surprised by the change in cg with the gear up/down. The test flights went well except for the snap/roll off but I was a bit surprised by the amount of trim required after the gear was down. I have Electron retracts and they are pretty "hefty" which causes a lot of weight to swing around during retraction/extension. I was taught many years ago by some guys who had been flying models over 50 years...(yeah, I know that makes me an official "old fart") Nose heavy airplanes fly poorly - tail heavy airplanes fly once. They also taught me that a airplane that is excessively nose heavy is prone to snapping out of a loop and dropping a wing during landing. I have been studying this very subject on the SkyMaster F-4 (my next project). Nose heavy jets have lots of problems such as long takeoff rolls then jumping off the ground during takeoff, diving with flaps and other nasty things. The guys who have the balls to move the cg back have now found the jet flys best with the cg 50 - 90 mm back from the original manufactures recommendation. BV recommended cg's for his products are slightly nose heavy. He does this to help ensure success on the test flights which allows us to move the cg back to one which is comfortable for the pilot. (See my previous statement on nose vs. tail heaviness). I have really been careful on this Flash..even with all my experience I have dorked 2. The first one on the 4th flight (which I believe was too nose heavy as it rolled off on landing just like this one) and #2 which I just plain "dumb thumbed". I'll give an update after I fly again on Sunday, 20-30 kt winds forecast in South Carolina for the next 2-3 days.
Good Luck! Jay
04-07-2016, 03:47 AM
#5068
DBSonic..there are two different symptoms of nose vs tail heavy takeoffs. A nose heavy jet requires a lot of speed to rotate and when the elevator becomes effective it will just jump with a high rate of climb. The elevator is effective after you are airborne due to the higher speed. A tail heavy takeoff will begin to rotate early (before real flying speed) then stall or roll of with the nose up, elevator has little effectiveness in the nose down position. In the real jet world an Airbus has a "forward cg" chart. When the cg is forward of a certain point we have to factor in a weight penalty to artifically increase thrust compared from the normal weight takeoff thrust. We also have to add a few knots to the V speeds to allow for more elevator effectiveness to get the plane to rotate properly. We normally try to fly with the cg in the mid to aft range for efficiency and performance. Ok guys go ahead an beat up the bus, I have thick skin and 15 years on FiFi. I have also flown numerous Boeing jets which are good jets too, just a different design. The big difference is I eat lunch from a tray and Boeing guys eat from their lap.
Bluebus. I agree on crow, it reduces the angle of attack at the tip and forces the stall to progress from the root to the tip, the secret to a successful slow flying airplane. For the guys who still dont believe just look at an F-15 from the side, it has a huge amount of washout to increase stability at slow speed, crow does the same thing on a wing without washout. I guess from your name you are a JetBlue guy? I've got 15 yrs on Fifi at UA, a professional f/o. I really enjoy putting my feet on the footrests, folding my arms and telling the Cap..."your decision boss". I also dont work weekends, nights and holidays by staying in the right seat.
Bluebus. I agree on crow, it reduces the angle of attack at the tip and forces the stall to progress from the root to the tip, the secret to a successful slow flying airplane. For the guys who still dont believe just look at an F-15 from the side, it has a huge amount of washout to increase stability at slow speed, crow does the same thing on a wing without washout. I guess from your name you are a JetBlue guy? I've got 15 yrs on Fifi at UA, a professional f/o. I really enjoy putting my feet on the footrests, folding my arms and telling the Cap..."your decision boss". I also dont work weekends, nights and holidays by staying in the right seat.
Last edited by tp777fo; 04-07-2016 at 03:54 AM.
04-07-2016, 03:53 AM
#5069
Thread Starter
See, I wrote the UF Manual addendum and did not say gear up or down :-) But I always check it gear down. Obviously changing the gear/leg type will change things, the Behotec nose leg and wheel is quite light weight, the manual can't cover for other peoples choices...
The curved wing tips on the UF already do the job of a slightly raised aileron, so raising it more just dumps lift. I'm sure that I have flown more UF models than anyone alive...pretty certain on that, maybe 50 different models-so as far as set ups go I think I have a good idea on what the model needs.
But, that all said different thumbs and brain-thumb combos might need something different to convince them, when I set up for a customer I tailor the settings to suit the owner...cause he has to fly it most, no me :-)
Dave
The curved wing tips on the UF already do the job of a slightly raised aileron, so raising it more just dumps lift. I'm sure that I have flown more UF models than anyone alive...pretty certain on that, maybe 50 different models-so as far as set ups go I think I have a good idea on what the model needs.
But, that all said different thumbs and brain-thumb combos might need something different to convince them, when I set up for a customer I tailor the settings to suit the owner...cause he has to fly it most, no me :-)
Dave
04-07-2016, 04:14 AM
#5070
Dave, I originally balanced gear down as it was what I was taught, but when I read the manual yesterday (yeah I know, I should have read it a little earlier) the UF addendum I have states gear up. My Flash #2 landed very slowly without crow and I dont have crow in this one. I believe in solving one problem at a time. I might try crow after I get the cg where I like it just to see what it does. I have a FB Dolphin that loves crow...different jets and different problems require different solutions. Thanks for your input, I very much value your experience with this jet...thats why I asked. You ARE the Flashmaster!
04-07-2016, 04:48 AM
#5071
My Feedback: (57)
DBSonic..there are two different symptoms of nose vs tail heavy takeoffs. A nose heavy jet requires a lot of speed to rotate and when the elevator becomes effective it will just jump with a high rate of climb. The elevator is effective after you are airborne due to the higher speed. A tail heavy takeoff will begin to rotate early (before real flying speed) then stall or roll of with the nose up, elevator has little effectiveness in the nose down position. In the real jet world an Airbus has a "forward cg" chart. When the cg is forward of a certain point we have to factor in a weight penalty to artifically increase thrust compared from the normal weight takeoff thrust. We also have to add a few knots to the V speeds to allow for more elevator effectiveness to get the plane to rotate properly. We normally try to fly with the cg in the mid to aft range for efficiency and performance. Ok guys go ahead an beat up the bus, I have thick skin and 15 years on FiFi. I have also flown numerous Boeing jets which are good jets too, just a different design. The big difference is I eat lunch from a tray and Boeing guys eat from their lap.
Bluebus. I agree on crow, it reduces the angle of attack at the tip and forces the stall to progress from the root to the tip, the secret to a successful slow flying airplane. For the guys who still dont believe just look at an F-15 from the side, it has a huge amount of washout to increase stability at slow speed, crow does the same thing on a wing without washout. I guess from your name you are a JetBlue guy? I've got 15 yrs on Fifi at UA, a professional f/o. I really enjoy putting my feet on the footrests, folding my arms and telling the Cap..."your decision boss". I also dont work weekends, nights and holidays by staying in the right seat.
Bluebus. I agree on crow, it reduces the angle of attack at the tip and forces the stall to progress from the root to the tip, the secret to a successful slow flying airplane. For the guys who still dont believe just look at an F-15 from the side, it has a huge amount of washout to increase stability at slow speed, crow does the same thing on a wing without washout. I guess from your name you are a JetBlue guy? I've got 15 yrs on Fifi at UA, a professional f/o. I really enjoy putting my feet on the footrests, folding my arms and telling the Cap..."your decision boss". I also dont work weekends, nights and holidays by staying in the right seat.
Dave, I've never heard of the wing tips turning up assisting with washout. I thought they were a form of sharklet that stopped the high pressure on the bottom of the wing from moving up the tips to find the low pressure on top (high seeks low). There for reducing drag from wingtip vortices making it faster & more fuel efficient. I've only flown 1 UF though, & I'm sure you have forgotten more about this plane than I will ever know..lol. But it seemed to like to drop a wing in the flare until I added the mechanic washout (aka crow).
Last edited by BlueBus320; 04-07-2016 at 05:18 AM.
04-07-2016, 05:50 AM
#5072
Thread Starter
Here is a screen shot of CARF's web site manual on the UF...nothing about gear up or down!?
Jay
Normal end plates yes, but if you look at the UF tip it is not just a shark fin-or end cap, it washes out (up slightly)
Dave
Jay
Normal end plates yes, but if you look at the UF tip it is not just a shark fin-or end cap, it washes out (up slightly)
Dave
04-07-2016, 10:02 AM
#5075
