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andoman 06-07-2021 07:23 PM

HR2 Gear Legs (F1 mod?)
My HR2 is at the “paint and panel to go“ stage. Fortunately I acquired it that far along.
I’ve read every Rocket thread and searched high and low throughout the RV gear leg stiffener threads.
My questions:
-should I seriously consider the F1 mount and it’s tapered socket leg upgrade?
-If not, what gear leg stiffener configuration should I move forward with?
My gear leg stiffener goals are aimed squarely at lessening the aft flexing of the legs during braking given the design’s light weight on the tailwheel and very flexible gear legs.
I found this recent -4 thread compelling (see pix links in post #4):

Thanks in advance and thanks to all the brilliant Rocket and -4 forum contributors over the decades.


rv699jb 06-07-2021 07:49 PM

F1 gear
Another point to not let lightly slip by, is that the F1 gear mod. moves the tires forward a few inches. This might be more important in preventing nose overs than the stiffness of the legs. I don’t think you would be disappointed with the F1 mount and gear legs upgrade.
Jim Baker
F-1 Building

andoman 06-07-2021 08:16 PM

Thanks, Jim, for the quick reply.
The improved geometry of the F1 gear is exactly why I’m asking the question.
The majority of the HR2’s seem to be flying fine with the stock gear, but it is less than optimum.

Tom Martin 06-07-2021 08:49 PM

The standard F1 mount will not fit a HRII fuse as the F1 is wider at the bottom mounts. It might be possible get a special one made. Contact Vince Frazier

Tom Martin

Little Al 06-07-2021 09:15 PM

Vince @ F1 aircraft now has available an engine mount available for the HR2 that has F1 geometry and accepts the F1 gear legs. Insurance statistic is something like 50% of all HR2s end up on there nose but thats only the ones the insurance knows about. John Harmon will tell you he believes 90% is more accurate. The price of a prop and 540 overhaul I would say YES its worth it.

sailvi767 06-08-2021 06:00 AM


Originally Posted by andoman (Post 1531500)
Thanks, Jim, for the quick reply.
The improved geometry of the F1 gear is exactly why I’m asking the question.
The majority of the HR2’s seem to be flying fine with the stock gear, but it is less than optimum.

The majority if you call that 51% might be doing fine but at least 30% and probably closer to 50% of the Harmon’s have been over on their nose. That is the reason Rockets have such horrible insurance rates. The F1 has been unable to distance itself ftom the Harmon to get lower rates.
The standard rule of thumb for a tail dragger is 5% of the weight should be on the tailwheel. Most F1’s are 50 to 70lbs on the tailwheel. The Harmon’s I have looked at had 20 to 30. A 1300lb aircraft should have 65lbs on the tailwheel.

titanhank 06-08-2021 11:39 AM

My hr2 had 19 lbs on the tail when i got it. I talked to john and several other rocket guys that recommend 35-40 lbs on the tail. John’s comment was “ throw a couple cases of oil in the back and go fly, you will love it”. I put a 4 gal smoke system in the cargo compartment and added 20lbs of lead dive weight to the aft elevator spar. This gives me 41 lbs on the tail with full smoke oil. It flies beautifully and has no tendency to nose over if you keep the stick back. It flies like a big engine airplane should, you just have to respect it on the ground.

andoman 06-08-2021 12:41 PM

I appreciate the comments.
My Rocket has a 15 gal aux fuel tank in lieu of smoke tank.
I really hope to hear more from those with time in HR2’s with standard gear.
Thanks again

vfrazier 06-08-2021 03:00 PM

Indeed we do make such a part:

HR2 Rocket Lycoming IO-540 Engine Mount – using F1 gear legs and leg geometry

Tom Martin 06-08-2021 04:41 PM

I have owned two HRII aircraft and flew a total of 6 or 700 hours on the two of them. I never had the tail come up on the ground but I was really careful. (maybe lucky)

Two real gotcha scenarios; the first is on initial start up; if you look down for a few seconds and the plane starts to roll forward; your head comes up, you jam on the brakes and over it goes.

The second is; heavy application of brakes while taxing. Easily can happen when you are in a line up waiting for clearance, push forward, apply too much brake too fast and over it goes.

When I sold my RV4 the gentleman started the aircraft at a high power setting and it went over as well. Fortunately he had a wooden prop and there was limited engine damage.

The F1 is much more solid on the main gear due to the wheels having been moved forward and also the gear legs are stiffer.

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