NACA 66 Special A/BGS

[Rex Schimmer]

Rob,
The front end looks great! I do suggest that you add an orifice to the flow line for some dampening, my bet is it will be smaller than .030 to be effective. You might want to consider using a pair of flow control valve that have an internal check valve that allows free flow in one direction and controlled flow in the other. You would connect them in series with the "free flow" arrows, which will be stamped on the valves, pointing at each other. This set up will give you the ability to set both compression and rebound dampening. I would also not consider using heavy oil as a method of changing dampening as you will find it is very temp sensitive. Something very thin like ATF or MIL 5606 would give the best results. If you go with the flow control valves they are available with extra fine adjustment which I would recommend. You do not want to use what are know as "pressure compensated" flow controls as they typically require at least 150 psi differential to work. Let me know if you want to go this way I can get the correct part numbers for you and maybe even "free".

Rex

[SPARKY]

Rob and team

[robfrey]

Rex, funny you mentioned that. I just ordered some flow control valves from McMaster. They should be here tomorrow morning. I only ordered the double direction flow though. I was wondering if you could do exactly what you said by running the valves in series but opposite directions but that seemed too easy to work. LOL
I come from a radio control car background (1/10 scale dirt oval). After a lot of experimenting, we went back to a single dampened rate (compression and rebound). Let me get them installed tomorrow and see what she feels like with a single comp/rebound adjuster.
I'm glad you have some experience with this. I will probably need your help.
Was a bit rough getting the air burped out of them.

[robfrey]

Here are some pics of the individual pieces of the front suspension.
Javier DeLeon did all the CNC mill work and as you can see it is all very beautiful and the finishes on the bores are awesome. There does not appear to any leaks so far.
Thank you very much Javier!







Hole in top of spindle locator is for welding in a 3/8" pin for die spring pilot.


Spindle subassembly


As soon as we are happy that everything is working like it is supposed to, all steel parts will be ferritic nitrocarburized  and teflon treated for surface hardness, corrosion control, smoothness, and appearance. This is the same processed used on all the new nitrogen spring pistons if they are coal black.

[DND]

Hi Rob

Front end looking very nice, i see you are still using the teflon tape in the front end hose fittings.

Better throw that stuff away or give to your local plummer as that is what it was made for, not aircraft or racing machines as it can come back and bite you right in the arse.

Don

[robfrey]

Hi Rob

Front end looking very nice, i see you are still using the teflon tape in the front end hose fittings.

Better throw that stuff away or give to your local plummer as that is what it was made for, not aircraft or racing machines as it can come back and bite you right in the arse.

Don

Yeah, I want to change over all the fittings to SAE style o-ring fittings eliminating the need for any kind of thread sealant. I don't know what I was thinking using NPT except I did not have tooling to install SAE ports.

[DND]

Hi Rob

Loctite makes a sealant for just about everything a guy would need, might be good to have some of that too for what ever might come up.

Those sales reps are good prople to work with on a project like yours, like samples !!

All it takes is a call or two.

Don

[Rex Schimmer]

Rob,
Really like the your front "suspension" design, am planning something similar on my lakester. One thought is to use Bellville washers in place of the die spring, they are pretty much self dampening and you can change spring rates by the way you stack them. I know it has been said before regarding teflon tape but if you use it make sure you do not put it on the first 2-3 threads of a pipe fitting, gives you a better chance to not have it in the system, the Loctite thread seal is the best though. Also like the teflon coating on the suspension parts, I worked on some off shore oil transfer buoys once, a long time ago!, and we teflon coated all of the bolts, washers and nuts for corrosion resistance. Seemed to work as they are still working today.

Rex

[Jon]

Very nice work as always Rob.

Thanks for sharing.
You don't get any measurable bump steer generated by the main drag link from the bellcrank to the back wheel?

Cheers
jon

[robfrey]

Very nice work as always Rob.

Thanks for sharing.
You don't get any measurable bump steer generated by the main drag link from the bellcrank to the back wheel?

Cheers
jon

Correct, no measurable bump steer. This is one of the reasons I ran the linkage to the back wheel as the link would be longer and would induce less bump during the 1.25" of wheel travel.

[Dean Los Angeles]

McMaster sells belleville discs. Cheap way to have flexibility over spring rates without buying lots of springs.

[robfrey]

Yeah I thought about Bellevilles but I believe the die spring was better for this application. Used both Bellevilles and die springs in my former occupation.
Tha advantage the die spring had here was that it was simpler and easier to keep centered in spindle without rubbing the bores. I used the Danly brand spring as it is wound from trapezoid shaped wire. During the winding operation, the outside is stretched and ends up in a rectangular cross section. Danly also has a great catalog that makes picking the right spring pretty easy.

[robfrey]

Got the McMaster dampeners (needle valves) installed today. They did nothing originally. Easy to diagnose as I closed the needle valves all the way and the suspension still moved. You guessed it. Air in the system. Figured out a better and easier way to bleed the units and this solved the problem. Now suspension is stiffer and I have total control over the dampening. Seems like1.5 turns out on each valve gave me the feeling I'm looking for.  

[robfrey]

Got new tool in the shop today.
Blaze 2 CNC plasma cutter. Arrived in crate this morning and I made the first part (rear wing rib bracket) on it this evening.

[robfrey]

For reference, that is a 3" hole in the center and it took a little over 1-1/2 min to cut. I'm amazed. Bad thing is that it makes a lot of smoke and fumes. Might need to hook it up to our ventilation system.