Trailing Link Suspension nose gear

I have received emails from RV owners asking if Custom Flight Systems has a system that could be adapted to work on some of the nose gear models. CFS has prototype castering nose gear for the AVID and Arion Lighting aircraft. See photos at www.CustomFlightSystems.com (caster info) http://www.customflightsystems.com/Caster.html

The AVID caster nose gear has 8 inches of progressive spring suspension travel with 6 inches of downward movement.
11 inches of ground clearance to the tension nut at the base of the nose gear leg with a static load on the wheel.
5 inches of ground clearance to the base of the nose gear leg at full compression less tire compression.

Vertical static load testing has been conducted per FAR 23.499 at 2.25 times the vertical static load on the wheel. The dynamic load testing for the AVID was at 300 lbs this was simulated using a air ram and compressing the nose gear to the pavement at 55 mph with the nose gear off center to induce shimmy. I can post the video on www.youtube.com if there is interest.
The gear leg is not designed to flex and the trailing link suspension can be setup to absorb 2.5 times the static load. The gear leg has a inner 4130 tube with a outer aerodynamic 4130 tube that has inner gussets that are all welded together to the tubing that makes it light but rigid.

Questions:
1.What is an approx two blade ground clearance with the standard RV nose gear using a Lycoming O-320 and O-360 or other engines?
2.Static nose wheel weight for the Lycoming O-320 and O-360 or other engines (~Min – Max range) Is 320 to 375 lbs a good range?
3.Is there data showing the force needed to bend the RV motor mount nose gear bracket?
4.What is a reasonable system failure load on the front nose gear (lbs)?
5.Full compression load on the overload springs for the CFS nose gear _____ lbs (2.25 x static)?
6.Can the RV have a slight positive angle of attack (nose high) to improve ground clearance?
7.Is there a nose gear assembly target and max weight range?
8.Is there a engine mount drawing with tube size, wall thickness and angles? (Or loaner hardware)


Thank you
Wade Schmidt
Custom Flight Systems LLC

Wade,

I live in Ephrata and have a 6A motor mount that you're welcome to borrow for measurements. I'll send you a PM with my cell number.

Nate,

Thanks for your support that will help with the test stand design and interface for the nose gear leg.

Wade

A few photos of Wade's castering nose gear design...

Now we're cookin'!

This looks seriously good!

Huge clearance between the nut under the swivel and the trailing link suspension isn't breaking any new ground, really...very proven.

Say Wade, have you determined that the RV's lower motor mount is strong enough to take the forces of a stiff leg?

Thanks,

I reviewed information from the online NTSB reports:

NTSB Case No.: ANC05LA123
The FEA also revealed that the aft force required to deform the strut sufficiently to produce contact with the forward side of the gear to the surface was between 1,000 and 2,000 pounds, depending on the amount of the rearward deflection used in the analysis.

NATIONAL TRANSPORTATION SAFETY BOARD
OFFICE OF AVIATION SAFETY
WASHINGTON, D.C. 20594
June 21, 2007
VANS AIRCRAFT MODEL A SERIES AIRPLANE
NOSE-OVER ACCIDENT
PHOTOGRAPHS

After reviewing the reports, there was no documentation of engine mount failures. The photos showed the nose gear legs were still attached to the aircraft. The 1,000 and 2,000 pounds of force needed to bend the nose gear leg to the point of contact with the runway may indicate that the engine mount was capable of absorbing this force. I have not tested this assumption. It is acceptable to have the engine mount deform during this type of failure. The report did not state the forces needed to deform the gear to the point shown in the photos. If there is interest in our nose gear design for the RV we will perform additional prototype testing per FAR 23.499. Thanks to Nate, he has offered to loan us a RV6A engine mount, to help with the test stand design and nose gear leg interface.

I have listed several question on the Trailing Link Suspension nose gear post that need to be answered before we can get started and if someone has data or insight to what the test parameters need to included it will help.

Thanks
Wade
CFS

If you're gauging interest...

I'm very interested! Looks like great design but I'm completely ignorant of the subtleties in engineering...I would love it if it is more tolerant of marginal surfaces.

Jeremy Constant
RV7A 110hrs

I'm very interested as well.... please keep us in the loop as to your developement progress!

interested.

Bevan

After stooging around on the website, it appears that designing a wheel pant (spat) for the trailing link nose gear might be an issue.

Without a wheel pant, the drag would be very noticeable, I would think.

Welcome to VAF!!!!

Wade, welcome aboard VAF. Great to have you here.

While the design should be workable (IMHO), I suspect the materials should be scaled up to account for the increased weight of the RV's over the Avid.

Good luck with the design,