NMPRA

That is a lot of bolts just to stabilize the plastic shell in front of the firewall. Just don't get it. I have seen the glass nose vibrate like crazy without tying it to the mount.
The web from beam to beam is nice dut dosen't the motor tie the beams together when bolted in place. I think you get little from the front end. Models with full nose rings are a bit stiffer in front but still a plastic shell offering little support fot the beast.
Just my thoughts.

The theory on the front cross beam is a simple one. It gives much more glueing surface from the mount to the G10 board so that things don't vibrate loose after numerous flights. Also it does stiffen the front end even more when it's incoorporated into the front of the fuse.
All of the hints that I have posted are things that have helped me with my race program. These hints might not work for everyone. If there are other or better ways to accomplish the goal of more speed, then by all means use them. Von Der Hey.

Tom has been on the fence about front mounts as long as I have known him. But we still love him.
Bet you get no distortion of the case with the N mount.

I believe Tom's main question/interest.. Is why the need for 5 #6 screws to hold the fiberglass cross beam adapter in place.? I assume you tie the fiberglass beam to the side of the fuse with carbon filled epoxy? And with the mount already having a aluminum cross beam...why not just bond the aluminum cross beam without the fiberglass adapter? what do you lose structurally by not having the fiberglass adapter in place?

Cheers,
Randy Bridge

When I posted this information I was only trying to share the things that I fell that have helped increase the performance of the engine and airframe. Again this is only my opinion. I am a truck driver, not an engineer, scientist or genius. Good luck, Von Der Hey.

I have to agree with kurt. That's one nice test stand.

Lee, can you elaborate on why no peak on the test stand. My thoughts are a solid test stand would prolly give you the most accurate rpm.

I don't disagree with the ring type nut plate but if secure when you tie down the front to the fuse and several flights later you snug up the mount you could pull thd front loose. Stabilizing the front shell is not a bad idea but little gain for the mount. Good solid firewall install is most important. If, when you glue the mount in, you pack the holes in front of the blind nuts with epoxy the blind nuts will not pull through. Always grease the bolts befor you do final install. Service is golden.

I thought that the ring type nut plate sold by Terence was the best. It was an aluminum ring with lightening holes and PEM nuts pressed in. Surely there are still some of these around???

I have never greased the bolts on my mounts. This goes way back to F1 and QM15 days. I was told that everything needed to be solid and if done right they shouldn't come loose. I roughen up the back of the mount, fill the blind nuts with epoxy and the front of the firewall. Install the mount (glued in place) and tie down the front. I have used 1/2 rings like Lee. I have used two bolts glued to the nose like Lyle. I have had mounts come loose, I have had airplanes last 30 seconds. I have airplanes last years. In the end it is all personal preference. I do believe tying the front down using either method is better than not doing it.

DK

I haven't been racing Q40 for all that long so I may be all wet in my reasoning.. I always tie the mounts down because any vibration created was done so at the expense of power.. If something is shaking, spinning, rattling, etc, it is only doing so by converting the power from the engine into those movements.. If the power is going into those movements, it's not going into the prop.. Not saying this is correct, just what I've always been told or done myself.. So, for me, the mount is part of the air frame, never to be removed..

vonderhey wrote:This info is directed towards Kurt but would work for all. You can call up Mike @ APM and order the set-up that I use. .192 & .019 . Ask for no glue in the crank and the piston fit @ .280 to .290 Break it in just like Ray says and race it with a 7.4 X 7.5 After a few runs you should be leaving the ground around 25K to 25.5K Ray is right when it comes to the piston / sleeve fit. As accurate as Mike makes all of the engine parts the chroming and fitting is the biggest variable with these engines. However Mike makes them as good as they will ever get so just about every engine that leaves his shop is a sub-minute engine. Along with all of this information I must stress that a .58 engine will only go 1.04 or slower in a bad airframe. Having the front of the airframe rigid is as important as having a sub-minute engine. Von Der Hey.

Hello Lee,
Thanks for your info.

May I ask why you use those piston fit numbers? Is that a piston loose fit? How is the best way to measure?
One more, why don't you use a ramp crank?

Regards,
Alex

I've always wanted to have a "racing program" like Von Der Hey but so far all I get is static. I feel like the little girl in "Poltergeist" .. they're heeeere ....

But, FWIW, I share Tom's skepticism about whether the front tie-downs alone really do anything ... and equally so for a continuous nose ring. I'd much rather cut an opening in the nose ring so I can pop the engine in & out without having to remove the prop & spinner. But I can see the benefit of tying down the beams and also reinforcing the inside of the shell, at least up to that point, making sort of a Russian speed pan for the engine to nestle in. Seems to me the end result won't be to eliminate all traces of wobble through brute force (we don't have enough resin for that, nor can we afford the weight penalty) but just to quiet things down a bit. If nothing else, this may prevent secondary harmonics that will loosen up bolts, etc.

Once I was privileged to get a close look at one of the F3D airplanes (a Stiletto, I think) that Chip Hyde had used to set a record. I was shocked to see that the front of the mount wasn't tied down -- and it was one of those long mounts, for a rear-intake engine. Maybe he just didn't have time, or balanced his props really well, or flew so much better than everybody else that it didn't matter. But it gives me comfort to know that if I can't learn good habits from the fast guys, at least I've already copied some of their bad habits. Whee, I mount my motors just like Chip!!

Think how much faster he would have gone had it been tied down ;- )

rocket wrote:Think how much faster he would have gone had it been tied down ;- )

Or... How much faster you could go if you DIDN'T! OH SNAP.

DK

(ONLY ONE MORE WEEK OF BEING THE NMPRA PREZ!!!)

Touche DK