Pulse 25XT
07-09-2010, 06:17 AM
#2
RE: Pulse 25XT
I haven't flown that one but a 40 engine in 25 model plane does not sound right to me.
Would be better with a 25 two stroke or 30 four stroke I would think. The electrics are a bit weaker built and also lighter so there is no need to overpower them.
Would be better with a 25 two stroke or 30 four stroke I would think. The electrics are a bit weaker built and also lighter so there is no need to overpower them.
07-09-2010, 11:45 AM
#4
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RE: Pulse 25XT
My understanding was that a .40 4 stroke would be about equal to a .25 2 stroke? I am in the process of putting a saito .45 into the Pawnee 15-25E and Im actually concerned it wont have Enough power...
07-09-2010, 04:23 PM
#5
RE: Pulse 25XT
To me it is not simply about the maximum HP that you can get out of an engine, it also depends on what kind of flying you're after, so it is not that easy to give an exact "conversion formula".
I do not run 4 strokes myself but for sport use I think a modern 4 stroke 30 can replace a 2 stroke 25. The advantage is a more comparable weight and a larger prop swung at lower revs, i.e. a well behaving sport plane. If you looking for maximum power vs weight then I think you are better of with a 2 stroke anyway, at least in these comparatively small engine sizes.
The weight penalty of a 4 stroke 40 engine might make it fly like a brick while giving comparable power to a 2 stroke 25.
I do not run 4 strokes myself but for sport use I think a modern 4 stroke 30 can replace a 2 stroke 25. The advantage is a more comparable weight and a larger prop swung at lower revs, i.e. a well behaving sport plane. If you looking for maximum power vs weight then I think you are better of with a 2 stroke anyway, at least in these comparatively small engine sizes.
The weight penalty of a 4 stroke 40 engine might make it fly like a brick while giving comparable power to a 2 stroke 25.
07-09-2010, 07:18 PM
#6
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RE: Pulse 25XT
OS 25 AX 12.6 oz (with muffler) 9x5 10x5 prop
OS Surpass 30 10.4 oz (with muffler) 9x6 10x6 prop
OS Surpass 40 13.3 oz (with muffler) 10x6 12x6 prop
they all are pretty close within weight, i'm assuming my 26 4-stroke weighs approx the same as the 30 4-stroke...and that my TT 25PRO is comparable in weight to the 25 AX
OS Surpass 30 10.4 oz (with muffler) 9x6 10x6 prop
OS Surpass 40 13.3 oz (with muffler) 10x6 12x6 prop
they all are pretty close within weight, i'm assuming my 26 4-stroke weighs approx the same as the 30 4-stroke...and that my TT 25PRO is comparable in weight to the 25 AX
07-11-2010, 08:00 AM
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RE: Pulse 25XT
The .25FX is 10.8oz with muffler.
I would also consider the vibration levels that you might see with a 4-stroke. Many smaller 'e' models use lightweight servos that will likely fail with excessive engine vibrations.
I would also consider the vibration levels that you might see with a 4-stroke. Many smaller 'e' models use lightweight servos that will likely fail with excessive engine vibrations.
07-12-2010, 07:10 AM
#9
RE: Pulse 25XT
That AX sure sounds heavy, a two stroke 25 engine shouldn't have to weight more than about 10oz.
My advice is to go with lightweight stuff all the way, i.e. 10 oz for the engine and keep the rest lightweight too. Magnum/ASP/SC .25 would be lighter and cheaper than an AX.
I haven't used those servos myself, but they do sound strong enough. Just keep the weight low and almost anything will fly...
My advice is to go with lightweight stuff all the way, i.e. 10 oz for the engine and keep the rest lightweight too. Magnum/ASP/SC .25 would be lighter and cheaper than an AX.
I haven't used those servos myself, but they do sound strong enough. Just keep the weight low and almost anything will fly...
07-15-2010, 12:22 AM
#10
RE: Pulse 25XT
I put a Thunder Tiger .28 in a friends Pulse 25...it is a nice combination. I had to side mount it...cylinder at 9 o'clock position, in order to get the carb at a proper level to the center-line of the tank.
Had to remove a bit of material in the battery tray area to make room for the tank. After that, had to reinforce the same area to get strength back...and I laminated some additional 1/8" ply on the firewall.
I like the way the new TT .28 has both beam and firewall mounts cast into the case...it made it easy to just bolt the engine to the firewall.
The fuselage and tail structure is kind of light...don't know if the 4 stroke .40 would be a bit too much? I have a feeling that if you carefully beefed it up in the fwd. area (tank compt. ) and firewall, it should be ok. I have an O.S. .40 Surpass and could see it as an alternative to the TT .28
The wing is plenty strong enough, IMO...but the horiz. stab and elevators aren't all that strong...(seems to be a "family trait" because the tail feathers on my XT40 are a little wobbly too )
We also used Hitec 225 servos...
Had to remove a bit of material in the battery tray area to make room for the tank. After that, had to reinforce the same area to get strength back...and I laminated some additional 1/8" ply on the firewall.
I like the way the new TT .28 has both beam and firewall mounts cast into the case...it made it easy to just bolt the engine to the firewall.
The fuselage and tail structure is kind of light...don't know if the 4 stroke .40 would be a bit too much? I have a feeling that if you carefully beefed it up in the fwd. area (tank compt. ) and firewall, it should be ok. I have an O.S. .40 Surpass and could see it as an alternative to the TT .28
The wing is plenty strong enough, IMO...but the horiz. stab and elevators aren't all that strong...(seems to be a "family trait" because the tail feathers on my XT40 are a little wobbly too )
We also used Hitec 225 servos...
08-06-2010, 05:08 PM
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RE: Pulse 25XT
I just picked up a XT25 today to put a OS 40 LA back into service. The LA 40 is not the fastest engine in the world, and didn't fly my superstar 40 with any authority. I just hate having a motor sitting on the shelf not doing anything. There is a ton of side thrust built into the fire wall, does anyone think there is a difference in side thrust setting between glow and electric? I'm going to mount the battery and maybe the tail survos in the back to offset the weight of the motor. Scoot
08-27-2010, 10:22 PM
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RE: Pulse 25XT
The firewall is set at 2 down and 3 right, that seems excessive for a low wing plane. My Ultra sticks have zero right thrust in them. Does an electric powered plane have to have more down and right thrust than an glow plane? I'm not comfortable starting out with that much angle for my glow conversion. I'm mounting an OS 40LA in it by the way. Its an old engine that I had laying around and wanted to use. It ran great with a 10x6 APC, but it was pulling a larger plane around. I might a 12x4 or 5 with the smaller plane.
08-28-2010, 07:54 AM
#14
RE: Pulse 25XT
In principle a larger prop may demand a little more right thrust than a smaller one, but if you have ailerons then you can compensate using thoose too. Unless you're a pattern addicted flyer, but then I don't think you would ask here anyway. Also 2-3° is typically what one will get or remove with a set of washers so you could build as it is and then add washers later, to either increase or remove the built in thrust angles.
On the latest low wing conversion I did, it required more down thrust than it was set up for as an electric, think I have about 4° now rather 2° (haven't measure it after I tuned it for good flight).
I wouldn't worry too much about it, it will fly as it is without any problem and it will have too tuned in flight anyway.
On the latest low wing conversion I did, it required more down thrust than it was set up for as an electric, think I have about 4° now rather 2° (haven't measure it after I tuned it for good flight).
I wouldn't worry too much about it, it will fly as it is without any problem and it will have too tuned in flight anyway.
09-07-2010, 11:24 PM
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RE: Pulse 25XT
OK, I have time to get back on the conversion, and the LA 40 is just to long as is. I have checked smaller engines, and there all to long. Im going to cut 1.125" out of the firewall to mount the engine back where I want it. What did some of you do to overcome this problem?? I could mount the engine as is, but I would have to move the cowl forward 1.125" and it just looks wrong. Way to long out front.
09-08-2010, 09:23 AM
#16
RE: Pulse 25XT
On the ones I have done (not the Pulse) I modified a plastic hayes mount so that the engine could be positioned really close to the firewall. Do you have any pictures of your problem?
