quote:

ORIGINAL: Nick Yuhasz

quote:

ORIGINAL: rcguy!

Do you throttle up to check things out before flying like on a piston powered plane? Anybody else have any input on this?

Dave Rigotti

Dave:

At jet rallies, it is generally frowned upon to run up your turbine in the pits / start up area for safety reasons. Also, last year there was some emphasis on blowing debris from full throttle run-ups causing debris to get sucked back into intakes after circling around from the blast protectors in the start-up areas.

Most modern turbine ECU's do not need a full throttle run-up on the ground .....

Nick

quote:

ORIGINAL: TommyWatson

I seem to remember that Bruce recommended a "Startup Shield" to stop hot starts from damaging the airframe. Mine is a piece if 4" gal pipe on three legs. Works for me.

I think that even on a no flam start the heat will rise up with no airspeed.


Regards

quote:

ORIGINAL: BruceTharpe

Dave, the singed Monokote must be happening during startup. It sounds like you haven't been using any type of heat shield. My guess is that even though it's starting without flame, the slow-moving heat during ignition is probably doing the damage. I have routinely used my "hot box" (steel tunnel) for startups, then moved the model away from the box to do full-throttle runups before every flight. I've also done ground runs, out of the hot box, at WOT for several minutes with no burning of the Monokote. I did sheet the full length of the tail boom with stainless on my model, but that was before these ground tests, and before the thrust angle was set. Simply feeling the bottom of the tail boom and finding it cool to the touch made me decide to eliminate the weight of the extra stainless for the kit version.

Because of the finicky nature of my Ram 500 startups, I've never tried starting without the hot box. There was a time when I thought maybe you could do without, but now I think startups with some sort of heat shield should be mandatory.

Bruce
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BTE www.btemodels.com

quote:

ORIGINAL: BruceTharpe

I made a tunnel from three slabs of sheet steel, joined at the corners with angle iron. Weight of the hot box is 15, maybe 20 pounds. I've felt it after starts, and it's definitely warm. I thought about using a stove pipe, but it would either need legs or somebody holding it during startup. In the end, I thought the heavier tunnel was the best way to go because it could just sit there with no concern about being blown away. If you use a pipe, I suggest using as large a diameter as practical, and make it heavy enough that it can just sit there during startup.
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Bruce, and all:
I have flown *another* designers airplane with the similar engine configuration using a 6" dryer duct....single walled...on a 2X4 base for over 100 flights (and a compadre's for 10 more) with out a problem of heating the bottom, or blowing it down the runway.
(Common sense does need apply re: wet starts). Weight is less than a pond. Does it get hot? You bet! so just don't touch the metal as you move it away from the airplane to taxi. My unsolicited 2 cents is *KISS* does apply.

Greg

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(in reply to BruceTharpe)

quote:

ORIGINAL: BruceTharpe

I made a tunnel from three slabs of sheet steel, joined at the corners with angle iron. Weight of the hot box is 15, maybe 20 pounds. I've felt it after starts, and it's definitely warm. I thought about using a stove pipe, but it would either need legs or somebody holding it during startup. In the end, I thought the heavier tunnel was the best way to go because it could just sit there with no concern about being blown away. If you use a pipe, I suggest using as large a diameter as practical, and make it heavy enough that it can just sit there during startup.

With the Kavan brake activated, it should take quite a bit of force to turn. Not all your strength, but not fingertip pressure either. That's as much as I can quantify it. I actually added a dab of grease to the friction plate to help it turn easier. Maybe the idle thrust of the P-60 is higher - My model actually rolls to a stop fairly quickly on pavement without braking.

Bruce

quote:

ORIGINAL: rcguy!


Folks,
An update on the Kavan brake. I've run some "breakaway" torque tests and sent the results to Bruce. It seems his Kavan brake at 8 volts is holding about 5 times better than mine at 12.3VDC. The actual figures are irrelevant. Bruce is sending another unit for me to try. Stay Tuned...It looks promising!

Bruce is tops with customer service!

I'll fabricate a blast tube this weekend. BTW... I purchased AeroShell 500 turbine oil at $7.89 per qt from the oul-store.com Fast and cheap shipping!

Dave Rigotti

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ORIGINAL: causeitflies-RCU

I got my R54 yesterday from Bruce . I hope the brake works because I got it too, after considering cancelling that part of the order.

I am fighting the temptation to start unpacking the kit as there is no way I could get all that stuff back in the box. I have to finish another project before starting this one and if the parts get mixed together on my crowded bench well....it wouldn't be pretty!

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ORIGINAL: rcguy!

Looking Great! Nice colors and all. I have FOD screen envy!

Dave Rigotti