Van's Air Force
Don't miss anything! Register now for full access to the definitive RV support community.
ATSB recommends upgrading 7A and 9A nose gear
- Thread starter IowaRV9Dreamer
- Start date
wirejock
Well Known Member
RV8JD
Well Known Member
From Van's Service Letter:
"The new design weighs more, requires potentially significant adjustments to several major parts FWF when retrofitted to an existing aircraft, and in some cases (specifically where the existing aircraft has a CG close to the forward limits) may require a lightweight battery replacement and/or relocation of the battery (or other similar changes) in order to properly accommodate and configure safe aircraft weight and balance.
By way of illustration, during installation of the new mount and gear system on the Van’s Aircraft RV-9A factory demonstrator aircraft, the following changes were measured before and after the modifications described in this service letter had been completed.
NOTE: Your aircraft will not match these weight and balance figures; this information is taken from a single aircraft and is provided for illustration purposes only. You will need to re-weigh your aircraft and complete a new weight and balance document upon completion of your project.
• Empty weight: Increased from 1088 lbs to 1093 lbs (+5 lbs)
• Nose wheel arm: Moved forward 1.18 inches
• CG in specific typical max-gross-weight loading scenario: Moved forward
from 81.447 inches (21.60%) to 81.174 inches (21.08%)
• Nose wheel weight measured in specific typical max-gross-weight loading scenario: Increased from 318.0 lbs to 333.3 lbs (+15.3 lbs)
• Cooling changes: Due to the changes to the engine mount and gear structure near the exit area of the cowl, exit airflow was reduced. Louvers were added to increase exit airflow and properly cool the engine. Net result on the demonstrator aircraft after all modifications including louvers was slightly lower operating engine temperatures than before the changes, with improvement especially noted during climbs. Airspeed was unaffected."
By way of illustration, during installation of the new mount and gear system on the Van’s Aircraft RV-9A factory demonstrator aircraft, the following changes were measured before and after the modifications described in this service letter had been completed.
NOTE: Your aircraft will not match these weight and balance figures; this information is taken from a single aircraft and is provided for illustration purposes only. You will need to re-weigh your aircraft and complete a new weight and balance document upon completion of your project.
• Empty weight: Increased from 1088 lbs to 1093 lbs (+5 lbs)
• Nose wheel arm: Moved forward 1.18 inches
• CG in specific typical max-gross-weight loading scenario: Moved forward
from 81.447 inches (21.60%) to 81.174 inches (21.08%)
• Nose wheel weight measured in specific typical max-gross-weight loading scenario: Increased from 318.0 lbs to 333.3 lbs (+15.3 lbs)
• Cooling changes: Due to the changes to the engine mount and gear structure near the exit area of the cowl, exit airflow was reduced. Louvers were added to increase exit airflow and properly cool the engine. Net result on the demonstrator aircraft after all modifications including louvers was slightly lower operating engine temperatures than before the changes, with improvement especially noted during climbs. Airspeed was unaffected."
gmcjetpilot
Well Known Member
Per previous post upgrade is not trivial in time to install, modifications of existing systems, cooling (cowl) and cost . Loss of untility (speed and payload) small but it is something. Worth the upgrade? Totally up to you.
If anyone has done upgrade or about to, it would be great if you post your re-build mod on the forum with lots of pictures. May be this documented nose gear retrofit already exist on VAF or WWW. Please post link for others. Cheers
Thanks for posting Ref.
If anyone has done upgrade or about to, it would be great if you post your re-build mod on the forum with lots of pictures. May be this documented nose gear retrofit already exist on VAF or WWW. Please post link for others. Cheers
Thanks for posting Ref.
Maybe when I overhaul the engine, not likely before that.
As noted in the document from Van's, no measurable difference in airspeed was noted during testing.
What about 8-A
Does any one know why this modification is not offered for 8-A aircraft?
Does any one know why this modification is not offered for 8-A aircraft?
PaulvS
Well Known Member
See post #47 above, extract as follows:
"RV-8A
Van’s Aircraft has not retrofitted the new nose gear system on the RV-8A for two reasons. First, the number of these models is very low. Due to the low number of 8A’s flying or the type of pilots that are attracted to this aircraft, we have not seen failures on this model. Again, we feel the old nose gear design is adequate if flown properly. Our RV-7A demonstrator still uses the old-style gear and is regularly used for transition training. Some of us who work here who own RV A models also use the older style gear. Pilot training is key."
gmcjetpilot
Well Known Member
No "Measurable" difference does not mean no difference. Adding weight it is axiomatic you will increase basic empty weight, reduce usable payload, reduce rate of climb and yes speed & range, even if it's small or nil. It is hard to measure changes in speed loss of a MPH or two, but it's not impossible.
The original nose gear looks cleaner aerodynamically, but both new and old nose gears use the same 11x4.00-5 tire I believe. Correct me if I am wrong on tire size. Personally I think they should have gone to 5.00 x 5 like the RV-10. That would effect speed more, but it would add even more resistance to nose wheel digging in and pole vaulting the plane.
Cooling? I think that is effected, which can affect cooking drag and speed, but again this can be mitigated and a small loss. However it is not nothing.
I stand by my statement you will lose speed. How much no one can say. I would not argue with Van's saying loss of speed is not (easily) measurable. May be someone who has made mod can give a before and after.
Last edited:
I guess there is always room for argument based on the theoretical but I would bet the rest of the world is willing to accept a statement that testing showed no measurable speed difference…..
gmcjetpilot
Well Known Member
"I bet" is not a scientific statement. I did not say theroretical, I stated facts. You have no idea what "test" was done or definition of "measurable" means. Does it mean nothing? No. If it was nothing they woukd say that.b
So let me ask you this. If you make an airplane slightly heaver, slightly less aerodynamic gear (larger frontal area), and impead cooling air exit air glow (cooling drag) the airplane will get:
A) Plane will GO faster
B) Plane will GO slower
�� There is no free lunch. The difference is small but measurable not zero. You could remove weight in orher places and clean up fit and finish overall for lower drag and mitigate the loss of new gear.
Last edited:
Actually... I do have an idea.
I personally did some of the flight testing.
And it is for that reason that I called into question your personal opinion statement that it must be slower.
Additionally, I disagree with the idea that changes are always measurable. They are not.
If a change is small enough, I can be nearly impossible to detect.
You will likely cue on my use of the word nearly, and that is fine. If you want to argue that with enough effort a reduction in speed would be measured. That might be true (depends on how much the actual speed delta is) but as already mentioned, if the delta is that small, no one else will care... there will be a bigger effect on speed from not having cleaned the bugs off from the previous flight...
Last edited:
AlexPeterson
Well Known Member
I'm always skeptical when someone posts about some change they made to this or that, and then "airspeed increased 2 knots", or "CHT's dropped 10 degrees". It takes a lot of control of many variables to determine those kinds of changes, and a lot of data on numerous flights.
wirejock
Well Known Member
Delay
Must be more delays because I bought the kit with my Finishing Kit a long time ago. Hopefully Vans will catch up soon.
Must be more delays because I bought the kit with my Finishing Kit a long time ago. Hopefully Vans will catch up soon.
Actually I think that Dan has shown us that reducing cooling air flow by reducing the exit area actually reduces drag and therefore increases speed, though it does reduce cooling effectiveness. Not really new knowlege though, as many planes use cowl flaps to do the same thing, adding drag and better cooling only when necessary.
Last edited:
