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SuperTigre ST2500 on Gas

Old 05-20-2023, 11:28 PM
  #26  
1967brutus
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Then to me that sounds as if there is a non-return valve somewhere where it should not be: "Unchecked" crankcase pressure should not split tanks, checked pressure MIGHT split tanks.

FWIW, it is hard to make any prediction extrapolated to size, but on my smaller glow-to-gas conversions, when breaking in on gas I typically see a 500 RPM gain when comparing "first run from the box" to "fully broken in". But then I am only referencing to engines about half the size of your ST.
Old 05-21-2023, 12:26 PM
  #27  
planenutzz
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no there is not, it is a simple nipple. No might about it, it split several dubro tanks and they are hard to split.
Old 05-21-2023, 01:58 PM
  #28  
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That is what I mean... Bit weird, never seen that happen...
Old 05-21-2023, 04:43 PM
  #29  
planenutzz
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I have with the big ST engines. Mate of mine rand the big ST3250s in a few scale warbirds back in the 80s and 90s and had a few split with same setup.
Old 05-21-2023, 11:36 PM
  #30  
1967brutus
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That's weird... Because the Dubro tanks are strong...
Old 06-03-2023, 08:02 PM
  #31  
planenutzz
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Just to close this one out. I was not confident the ST2500 would develop the grunt the Mustang needs and deserves and while pondering this a post pops up on fascistbook by a mate of mine who was selling a ST3000!! mmm, hmmmm me thinks, a tad longer and a tad higher but should fit nicely.
Deal done, swapped over the MMM petrol conversion bits to the ST3000, installed and set up throws.

Ran it yesterday on the Mejinik 17x10, 8350 RPM. WOW Name:  smiley3.gif
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Right I thought lets see how it likes the Bolly 18x10, 8000 RPM and engine is much happier as it like the weight of the Bolly. It actually produces higher static thrust on the Bolly than the Mejnik. Bolly 21.65lbs static on a 24lb model.
Flew the Mustang this morning, boy what a difference! It roared down the strip and into the air, had to pull it back to half as it was that fast in the air. Loops from level flight.

It did feel different in the air . . .

Lined up for downwind, drop gear, flaps etc and had to hold quite a lot of back stick, never had to do that before.
Came in with a bit of power on and pulled throttle back like I usually do to flare it on the mains and it was hard to flare then reared up, got it leveled and landed, bumpy but ok.

Hmmm me thinks. Checked CG with help of another chap and yes quite nose heavy, the ST3000 must be quite a lot heavier. Moved both flight batteries and the ignition battery as far rearward as I could which is about where the pilots feet are but still nose heavy. Had to put 1ounce right in the tail via the access hatch there. Just a very slight nose droop which should be ok.
Fingers crossed for next flights.

Very happy with the ST3000 though, what a beauty! Name:  smiley16.gif
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Old 06-04-2023, 10:35 AM
  #32  
1967brutus
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Remarkable that the 25 and the 30 have such a big difference, but the beter for you. Congrats!
Old 06-04-2023, 12:28 PM
  #33  
planenutzz
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not remarkable at all, it is what I expected. QED.

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