Boomerang Sprint Build Thread!
06-22-2010, 09:59 PM
#1351
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RE: Boomerang Sprint Build Thread!
Try Dreamworks and Altecare RC. They both have retract sets for the sprint. I bought the set from Altecare and they are nice but the Dreamworks gear is a little better looking.
Chris
Chris
06-23-2010, 03:42 AM
#1352
RE: Boomerang Sprint Build Thread!
Sandor at Digitech does a nice set of retracts for the Sprint and is a helpful guy.
http://shop.digitech-turbines.com/
http://shop.digitech-turbines.com/
06-23-2010, 06:51 AM
#1355
RE: Boomerang Sprint Build Thread!
Yes, for sure. And if anyone wants to give me a quick and dirty summary here of build tips and potential screw-ups to avoid, it might be a good place in this long thread for it...kind of like the Cliff's Notes of the Sprint Build Thread 
06-23-2010, 07:22 AM
#1356
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RE: Boomerang Sprint Build Thread!
If you are used to building larger size plane,like a 120 to 140 size, I have good confident that Sprint is more or less the same. You will not have any problem. If you have doubt,you can always voice it out here,and we are here to help. It is also good to scan thro the pages here.
06-23-2010, 08:23 AM
#1357
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RE: Boomerang Sprint Build Thread!
be careful there is a left and right landing gear well. i didn't realize that untill to late..lol. very straight forward build. For safety i reglued all the servo mount areas (areas where servo mounts screw into).Also on my sprint everytime i tried to Z bend the pushrods in the kit you could feel the metal fatigue...i think they were too hard.so I replaced them with 4/40
06-23-2010, 09:10 AM
#1358
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RE: Boomerang Sprint Build Thread!
Finished one of these recently and here are a few tips. Remember to fuel proof all exposed wood where a leak from the tank or UAT can end up. BVM Heat Shield the entire top and bottom of the engine compartment. Reinforce the battery tray -I fiberglassed the bottom of it from the nose gear compartment. The Dreamworks gear are very good [but will cost more than the ARF]. I replaced all the hardware just out of personal preference. With an P-80, I needed to add down thrust [washer under the front of the mount]. I epoxied the booms to the middle wing. Oh, and don't forget to insert the wing tube before you fly.
06-23-2010, 08:19 PM
#1359
RE: Boomerang Sprint Build Thread!
Thanks for the tips, guys. Yes, I was looking over the instructions and noticed the z-bend steps, and immediately was thinking if there was a better way. I also noticed in the instructions that the fuel tank be secured to the formers or it will rip out under negative 'g'...that got me thinking that the structure might need beefing uo. But damn, here we go adding weight...maybe I need to stick with my P-120!
My next question would be servos. I'll admit I haven't yet had time to read this thread, so it's probably in here. But, at the risk of getting flamed for asking before reading, I plan on using an AR9100 with two 2200 mah A123's to power the system.
My next question would be servos. I'll admit I haven't yet had time to read this thread, so it's probably in here. But, at the risk of getting flamed for asking before reading, I plan on using an AR9100 with two 2200 mah A123's to power the system.
06-23-2010, 09:42 PM
#1360
Senior Member
RE: Boomerang Sprint Build Thread!
I flown the Sprint for 23hrs, I recently expoxied the booms to the middle wing too. Noticed some free play after a while. Now it feels solid.
06-23-2010, 10:19 PM
#1363
Senior Member
RE: Boomerang Sprint Build Thread!
i had a small discussion with fellow flyer regarding putting a 120 into a sprint. We all agreed that if u use 120,DONT limit its throttle limit. As such when u put that engine in sprint, it already adding more weight to the airframe. THe danger is only when u fly in straight line, on max power,it stressed the airframe due to the drag. BUT, on low speed and mid range ( that is what u use most of the time), u will need the extra power to get out of situation when needed. I hope you able to understand what I mean...
06-23-2010, 10:22 PM
#1364
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RE: Boomerang Sprint Build Thread!
Used Sig Supercoat to fuelproof. UAT developed a leak on the maiden resulting in a flame out. Fortuntely, I got her down without damage. There was a pool of kero in the fuse thanks to the fuelproofing. Not sure if its the best product but it definetly helped.
Using two A123's and an AR9100 myself -working good. The only problem is they aren't as flat as other batteries so they won't fit in the battery compartment above the nose gear. Not a big deal, just had to add 2 to 3 ounces of lead in the nose. Using less than 200 mah per battery per flight.
Using two A123's and an AR9100 myself -working good. The only problem is they aren't as flat as other batteries so they won't fit in the battery compartment above the nose gear. Not a big deal, just had to add 2 to 3 ounces of lead in the nose. Using less than 200 mah per battery per flight.
06-23-2010, 10:23 PM
#1365
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RE: Boomerang Sprint Build Thread!
all those things will be perfect. 2 sugestions i would use the two 123s for the reciever and get one lithium maganese for the ecu. also if your using the 120 get the jettech 125 oz fuel tank. as for servos use the best you can afford. hitec 7985s all around would be great.
06-23-2010, 10:44 PM
#1366
RE: Boomerang Sprint Build Thread!
Great stuff guys, thanks. I should have added that my 120 came with a v6.0 ECU and a lipo, so I've got 3 batteries total. I may have to re-think the A123's. I just HATE to add dead weight. I like weight to earn it's keep, so to speak. My problem is I'm leery of NiMH and false-peak charges, and lipos need regulators, so that adds weight and failure points. I'm a little concerned about this jet and getting it 'porky', since it's balsa...seems fragile.
Seravios, yes I know exactly what you mean...use the power of the 120 in climbs, not WOT level down the runway. But, another issue is my -120 is an older, slow spooling model that I got fresh from a Jetcat visit and is "0" time (hence the newer ECU and lipo power) This slow-spooling has me concerned, and frankly played a large part in my decision to go with the Sprint...I could just see myself getting behind on the power when trying to land that big, heavy L-39 and crunching it in. A new P-80SE really seems like the way to go.
Sluggo
Seravios, yes I know exactly what you mean...use the power of the 120 in climbs, not WOT level down the runway. But, another issue is my -120 is an older, slow spooling model that I got fresh from a Jetcat visit and is "0" time (hence the newer ECU and lipo power) This slow-spooling has me concerned, and frankly played a large part in my decision to go with the Sprint...I could just see myself getting behind on the power when trying to land that big, heavy L-39 and crunching it in. A new P-80SE really seems like the way to go.
Sluggo
06-24-2010, 01:30 AM
#1367
Senior Member
RE: Boomerang Sprint Build Thread!
Sprint is not fragile. You will be surprise of how tough this box of match sticks (thats what some called it) can be...hahaha! And being balsa/ply,repair (if needed) is a piece of cake. Try to repair a composite jet,and let me know. Yup, with the old jetcat, the larger the turbine,the longer is the lag, frankly it is just a matter of getting use to it. Nothing serious acutally. My mentor been flyin the Kingcat with old P120 for 98 hrs...I sometimes have a go at it,no problem at all.
06-24-2010, 01:35 AM
#1368
Senior Member
RE: Boomerang Sprint Build Thread!
Or i feel a good option is to sell your L39, and buy a Kingtech K80E. Very very good spool up time. Very reliable engine and most important it is CHEAP. It suits the Sprint very well. LIght and powerful.
06-24-2010, 02:31 AM
#1369
RE: Boomerang Sprint Build Thread!
ORIGINAL: VF84sluggo
Great stuff guys, thanks. I should have added that my 120 came with a v6.0 ECU and a lipo, so I've got 3 batteries total. I may have to re-think the A123's. I just HATE to add dead weight. I like weight to earn it's keep, so to speak. My problem is I'm leery of NiMH and false-peak charges, and lipos need regulators, so that adds weight and failure points. I'm a little concerned about this jet and getting it 'porky', since it's balsa...seems fragile.
Seravios, yes I know exactly what you mean...use the power of the 120 in climbs, not WOT level down the runway. But, another issue is my -120 is an older, slow spooling model that I got fresh from a Jetcat visit and is ''0'' time (hence the newer ECU and lipo power) This slow-spooling has me concerned, and frankly played a large part in my decision to go with the Sprint...I could just see myself getting behind on the power when trying to land that big, heavy L-39 and crunching it in. A new P-80SE really seems like the way to go.
Sluggo
Great stuff guys, thanks. I should have added that my 120 came with a v6.0 ECU and a lipo, so I've got 3 batteries total. I may have to re-think the A123's. I just HATE to add dead weight. I like weight to earn it's keep, so to speak. My problem is I'm leery of NiMH and false-peak charges, and lipos need regulators, so that adds weight and failure points. I'm a little concerned about this jet and getting it 'porky', since it's balsa...seems fragile.
Seravios, yes I know exactly what you mean...use the power of the 120 in climbs, not WOT level down the runway. But, another issue is my -120 is an older, slow spooling model that I got fresh from a Jetcat visit and is ''0'' time (hence the newer ECU and lipo power) This slow-spooling has me concerned, and frankly played a large part in my decision to go with the Sprint...I could just see myself getting behind on the power when trying to land that big, heavy L-39 and crunching it in. A new P-80SE really seems like the way to go.
Sluggo
Mike
06-24-2010, 02:36 AM
#1370
RE: Boomerang Sprint Build Thread!
ORIGINAL: VF84sluggo
My next question would be servos. I'll admit I haven't yet had time to read this thread, so it's probably in here. But, at the risk of getting flamed for asking before reading, I plan on using an AR9100 with two 2200 mah A123's to power the system.
My next question would be servos. I'll admit I haven't yet had time to read this thread, so it's probably in here. But, at the risk of getting flamed for asking before reading, I plan on using an AR9100 with two 2200 mah A123's to power the system.
Mike
06-24-2010, 05:54 AM
#1371
RE: Boomerang Sprint Build Thread!
I was wrong, went and looked and my A123's are 2300mah...got 'em here: http://www.hangtimes.com/a123_packs.html
I did see in the instuctions where it was recommended to go with max flap deflection and a crow setup. Up-ing the rpm is also a good idea, one I hadn't considered. What to do with the L-39 is a thinker. I could 'cannibalize' it, sell it as an ARF, and pretty much have everything I need to build the Sprint, short of a fuel tank and gear. Some folks already have their own engine. Or just sell it pretty much RTF as it is, just needing final accessory placement and CG balancing.
I did see in the instuctions where it was recommended to go with max flap deflection and a crow setup. Up-ing the rpm is also a good idea, one I hadn't considered. What to do with the L-39 is a thinker. I could 'cannibalize' it, sell it as an ARF, and pretty much have everything I need to build the Sprint, short of a fuel tank and gear. Some folks already have their own engine. Or just sell it pretty much RTF as it is, just needing final accessory placement and CG balancing.
06-24-2010, 08:36 AM
#1373
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RE: Boomerang Sprint Build Thread!
What's the advantage of the crow setup? Just looking to learn not saying one is better than the other. Have 700+ ft runway and have been landing without flaps [or crow].
06-24-2010, 08:40 AM
#1374
RE: Boomerang Sprint Build Thread!
I should think so on 700 ft!
The main advantage is to slow down considerably, the up ailerons act as air brakes and more importantly washout and help to prevent tip stalling at slow landing speeds at high alpha.
The main advantage is to slow down considerably, the up ailerons act as air brakes and more importantly washout and help to prevent tip stalling at slow landing speeds at high alpha.
06-24-2010, 08:43 AM
#1375
RE: Boomerang Sprint Build Thread!
ORIGINAL: madmodelman
I should think so on 700 ft!
The main advantage is to slow down considerably, the up ailerons act as air brakes and more importantly washout and help to prevent tip stalling at slow landing speeds at high alpha.
I should think so on 700 ft!
The main advantage is to slow down considerably, the up ailerons act as air brakes and more importantly washout and help to prevent tip stalling at slow landing speeds at high alpha.
Mike