George Gassaway
Well-Known Member
- Joined
- Dec 1, 2004
- Messages
- 197
- Reaction score
- 2
Just recently started posting to the forum, and ran across this thread. A number of things I might have posted have been said already.
Ken Parker wrote:
>>>>
I'll tell you one motor that I really want to try in my T25 when I get it finished - an Aerotech F12. I'm hoping that motor would really boost it up there.
<<<<
The F12 (or E12J RC version) ought to work out very nicely in it, not too little thrust and not too much thrust. The altitude increase probably will be more than the E9 and E12 (or F12) newton second ratios, since a lot of the early N-sec is used up in getting moving to a reasonable velocity (that is, 33% more n-sec might produce much more than just 33% more altitude).
Ought to be visible enough. After all, the F12 is a very wimpy F, not full power.
g_boxwood wrote:
>>>>
I checked the E6 specs: initial thrust is around 20.12 N which should be enough to lift it off; the only problem is that thrust suddenly drops to about 6 N for the remaining burntime which may be unsufficient to maintain an aggressive climb angle.
<<<<
Unless it was very lightly made, with very light radio gear (and battery pack), an E6 is probably too low thrust. Ive done an R/C model (SkyDart 2X) at 14 ounce liftoff mass on an E6, its pretty sluggish. Its happiest with about a 45 degree climb angle. And I know 14 ounces would be way light for the T-25/Centurian, so in imagining another 3-4 ounces to that combo, even 45 degrees might not be a shallow enough boost angle.
An interesting way to pep up the boost would be to use a D12-0 Chad-staged to an E9. Although the liftoff CG would be more rearward, so the model would be sensitive from liftoff till it staged. Also, there is the potential for the D12 casing to tumble up and hit the horizontal stab when it stages. The stab itself probably would not break but it might overstress the glue joints where it is attached to the rudder tips and knock the stab off.
FWIW - theres some photos of R/C models, and a few links, on my website:
https://members.aol.com/GCGassaway/rcgliders.htm
- George Gassaway
Ken Parker wrote:
>>>>
I'll tell you one motor that I really want to try in my T25 when I get it finished - an Aerotech F12. I'm hoping that motor would really boost it up there.
<<<<
The F12 (or E12J RC version) ought to work out very nicely in it, not too little thrust and not too much thrust. The altitude increase probably will be more than the E9 and E12 (or F12) newton second ratios, since a lot of the early N-sec is used up in getting moving to a reasonable velocity (that is, 33% more n-sec might produce much more than just 33% more altitude).
Ought to be visible enough. After all, the F12 is a very wimpy F, not full power.
g_boxwood wrote:
>>>>
I checked the E6 specs: initial thrust is around 20.12 N which should be enough to lift it off; the only problem is that thrust suddenly drops to about 6 N for the remaining burntime which may be unsufficient to maintain an aggressive climb angle.
<<<<
Unless it was very lightly made, with very light radio gear (and battery pack), an E6 is probably too low thrust. Ive done an R/C model (SkyDart 2X) at 14 ounce liftoff mass on an E6, its pretty sluggish. Its happiest with about a 45 degree climb angle. And I know 14 ounces would be way light for the T-25/Centurian, so in imagining another 3-4 ounces to that combo, even 45 degrees might not be a shallow enough boost angle.
An interesting way to pep up the boost would be to use a D12-0 Chad-staged to an E9. Although the liftoff CG would be more rearward, so the model would be sensitive from liftoff till it staged. Also, there is the potential for the D12 casing to tumble up and hit the horizontal stab when it stages. The stab itself probably would not break but it might overstress the glue joints where it is attached to the rudder tips and knock the stab off.
FWIW - theres some photos of R/C models, and a few links, on my website:
https://members.aol.com/GCGassaway/rcgliders.htm
- George Gassaway
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