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Hi guys, a while back I picked up an old F1 Grove GR7. I had dub Jett set up one of his FAI practice engines for me to run on an open stack. I balanced it where I thought should have been balanced but on the first flight, the second it broke ground it dove back to reconnect with Mother Earth. No damage besides busted prop and bent pride. However, now I am questioning the CG location with the double tapered wing.
Hoping somebody can help me out. I asked Dub as he flew the GR7 and he couldn't remember. I have been waiting for Brian from B&B hobbies to let me know as he has a couple and said he would check his and get back to me but after multiple phone calls and emails I give up. The airplane is beautiful and I just don't want to damage it over something stupid like incorrect CG
Thanks in advance.
Jeremy.

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Nobody knows anything?

Pylonracr

Jeremy.
I have never had that plane, so I can not give a measurement. Did you plot the wing and see where the CG is in relation to the MAC? I would think the old 25% should at least make it flyable. If your present CG is close to the 25% mark I would go over the plane carefully and check all incidences. If the thrust or tail is off in relation to the wing it could fly like your plane did.

Let us know what you find

Scott

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Hi Scott,
the airplane was raced for many years with both the formula one fuse and in fai with the fai fuse. It belonged to Andrew MacIndoe out here in western Canada. Andrew doesn't remember where the cg is on it. The wing has an odd shape to it. This strange double taper, kind of like a squared off elliptical wing.

HighPlains

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I think they used to call those models Kazi Killers. That design was from about 1990 or '91. I think it might have been done by Keith Davidson, who was a friend of Robby Grove if my memory is still working. Or it might have been designed by Jerry Small.

Pylonracr

Jeremy
Give this calculator a try http://www.nasascale.org/howtos/cg-calculator.htm. Go for a CG about 25% and compare to where it balances now. You may have to adjust a little for rounded tips, but it should be close.

Scott

kane

Since it was also used in the FAI version, it was designed by Jerry Small. Bob Brogdon just had one at this year's NATS. Maybe someone can ask him where the CG is. And yes it is called "KAZE KILLER".

DK

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Hi Dan, Jerry Small has a qm40 and fai kaze killer but this is an old formula one. Looks much different than the qm40 version.

kane

Agree. I was referring to the F1 version. A couple of guys flew their old Form 1 airplanes during a break at the NATS.

DK

Stevem9

I have one of these Kaze Killer too, is still in Kit form but its going to be cool to put together any info you guys might have reguard this kit including the CG would be great! I was going to put a old Nelson SS Q500 in it should be fun!


Any chance Jerry small has some plans of info laying around still??

allang46

Jeremy,
Did you ever get a CG measurement for your GR7 ?

I have one ready to fly, I can check the CG and post it if you still need it.

Allan

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Allan,
No I didn't, still trying to find one. If you could check yours that would be great, yours is the formula one version, not QM40? Formula one is what I'm looking for

allang46

Yep, Formula 1 is what I have.
I have had 4 or 5 of these and I always start with 2-3/8" from the center of the wing.
This good starting point, you can fine tune it from there.
Allan

LGM Graphix

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What do you mean center of the wing? Do you mean 2 3/8" from the leading edge where the wing would join in the middle?
Thank you, that's a great starting point!

LGM Graphix

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Here is mine with a Jett FAI engine set up for open exhaust.

allang46

Yep, center of wing from the leading edge, measure back 2-3/8" and start there.
She will not have any bad tendencies starting with that CG.
You can move it back a little from there if it does not handle to your liking, but that is a good starting point.

LGM Graphix

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Awesome. Thank you so much!

allang46

That is the same plane I have.
Looks like you need to open up the cooling hole in the front of the cowl.
Should look like a T.
Top of T across head and the bottom should be about 3/8" wide down towards the crank.
Open up around the pipe to let the air out.
Don't want to toast that new motor.

LGM Graphix

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There is lots of exit air on the bottom of the cheek cowl. The original owner raced it for years like that.

ashley chapman

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The plane in ? is it A 42 % F -1 plane as raced in USRA? Wingspan would be in the 10 foot appox length. I along with about 30 other guys raced these in late 90s into 2003. I will look for C G info. A person that might now of the top of his head is Horizon guy KEN Mcspaddon.

LGM Graphix

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Ashley Chapman,
No, it is an old Formula one .40 sized pylon racer, not the 42% version. Thank you though, fortunately alleng46 has one and gave me the CG location to start