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Jeff Brenhaug
12-30-2007, 08:17 PM
Any HR3 builders here?
I spent the Summer flying fires in SoCal and had the opportunity to meet John Harmon and his Rockets at Bakersfield and Porterville.
I have built the -8 empennage and have the HR3 plans in hand with the rest of parts to follow.
Any info would be appreciated.
Jeff

john02
01-04-2008, 06:13 PM
Jeff - I am in the same boat...still working on my -8 empennage though...Havn't seen a single website yet and still havn't decided on a 'lite' yet-if the W&B would work. Check the plans, though. The dimensions of the tail kit on the plans are for an RV-4 tail - even though one of the articles in the brochure says it has an rv-8 tail. Another post in the forums is from a guy who said that Harmon's III originally had an 8 tail but it was changed for some reason? Any info on that?

John

RVjim
01-04-2008, 09:35 PM
Jeff - I am in the same boat...still working on my -8 empennage though...Havn't seen a single website yet and still havn't decided on a 'lite' yet-if the W&B would work. Check the plans, though. The dimensions of the tail kit on the plans are for an RV-4 tail - even though one of the articles in the brochure says it has an rv-8 tail. Another post in the forums is from a guy who said that Harmon's III originally had an 8 tail but it was changed for some reason? Any info on that?

John

The HR3 had a RV-4 HS & elevators. The elevators were changed to the RV-6/RV-8 style counterweighted elevators with a HS tip added.

This resulted in a 2 knot increase in airspeed.

Jim Ayers

Jeff Brenhaug
01-05-2008, 08:56 AM
Thanks guys, after 372 views I finally got someone to chime in.
I was at Porterville airport (KPTV) when John Harmon and Matt Baker brought their rockets over to look at.
Matt's had the -8 tail and John's rocket had the -4 tail. John says I could use my -8 tail with no problems.
When you see them side by side the -8 tail looks big, but when you see the -8 tailed rocket by itself it looks good.
Hoping to gather some more HR3 builders into a network if at all possible.
Thanks,
Jeff

PhoenixRocket
01-05-2008, 09:36 AM
You might be adding my name to that HR3 builders list soon. I'm going to order the plans soon so I can wrap my head around the mods. What are the benefits of either tail? I'm still a little confused about why you would use a -8 tail vs a -4 tail.

Jeff Brenhaug
01-05-2008, 11:06 AM
The -8 tail has the counterbalanced controls, thicker skins.
AND..............I already have the -8 tail finished.
Either way is good, I guess.

PhoenixRocket
01-05-2008, 02:43 PM
I'm beginning to understand ...its all about personal preference. I keep hearing that F1s have a stronger tail, would it be a good idea to buy an F1 evo empennage kit? Will it even bolt onto a HR3? I guess the real question is would it be worth it? The evo's top speed is 265mph where the HR3, with its 'weaker' tail, has been tested to 320mph without any problems.

Jeff Brenhaug
01-05-2008, 05:02 PM
I would run that by John Harmon first.
My friend owns a Harmon Rocket with the F1 tail and slider canopy, it used to belong to Mark Fredericks (sp?) as "Check Six". The tail looks similar to the -8 tail but there are a ton of differences. Just looks similar.

rocketbob
01-05-2008, 07:42 PM
The later F1 tail kits have spars that are reinforced with 1/8" thick doublers. The CZ engineer did an FEA analysis on the tail and found some beef-ups were prudent. The airfoil thickness of the F1 tail is also 1/4" thicker in cross section at the HS aft spar. This increases the cube area of the HS spar making it stronger as well.

I have a gut feeling it would be difficult to overload the tail before the wings would break. Vibration fatigue is the enemy here, just watch a RV tail shake and rattle during start and runup. On high time RV's its not uncommon to find loose rivets on the fixed tail surfaces.

Floridagator
08-16-2008, 12:28 PM
Thread bump.

I still haven't found anyone on this site (or any other) who has started or finished a Harmon Rocket III.

I've had it in my head to build an RV3 for some time, but the HR3 seems like an order of magnitude more fun!

Does anyone have any building or flying impressions?

mark manda
08-16-2008, 01:32 PM
i was at L 45 a couple weeks ago just before Rosie flew in and I heard this high RPM radical high horsepower plane in and around the pattern. Yep. The HR-3 was out flying.