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RV-3 vs. Harmon Rocket I

Jumbo

Well Known Member
Hi,

I am trying to find out what the differences are - both structural and aerodynamic - between the RV-3 and the Harmon Rocket I. I am aware of the turtle deck and more HP however I don't have any knowledge really re the wings in detail and re any resulting change in flying behavior.

If you guys, more knowledgeable than me, would provide some insight I'd be glad.

Thanks, Heinz
 
Heinz, the Harmon Rocket is based on an RV-4, who's wings are a lot bigger in both chord and span. The fuselage is also a lot longer on a -4.

The Harmon's wings are shortened by one bay but uses all the ribs, just spaced closer together. The tailfeathers are also -4, bigger than the -3 and the guys usually use thicker skins back there.

Best,
 
Scratch what Pierre said. He wasn't paying attention.

The Harmon Rocket 1 was based on the RV-3. Like you I do not know other than the turtle deck and an angle value IO-360 engine what the difference is.

The HRII had lots of changes but again, no so sure about the HRI.

John Harmon is still around and may answer your questions.
 
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yes, HR I (only 4 built) - not HR II

Thanks gents,

As far as I understand the HR I is essentially a standard -3 with a "pumped up" motor and a raised turtleback. I am not aware of any change of seating location for CG reasons as all the parts and pieces were installed in the original locations.

So with the angle valve AEIO 360 I think the CG at Empty Weight (I know the MTV-12 helps over a i.e. a Hartzell) is important. Too, I don´t know about potential flutter of RV-3 control surfaces at say 190kts+ IAS.

Someone out there able to advise?

Heinz
 
Birds of a feather...

Hi,

I am trying to find out what the differences are - both structural and aerodynamic - between the RV-3 and the Harmon Rocket I. I am aware of the turtle deck and more HP however I don't have any knowledge really re the wings in detail and re any resulting change in flying behavior.

If you guys, more knowledgeable than me, would provide some insight I'd be glad.

Thanks, Heinz

Wie Geht's Heinz!

As you know the HR-1 was a modification of the RV-3 kit of which John Harmon is very familiar. He was one of the original RV-3 builders and went on to assist or build seven more. The HR-1 was basically a beefed up RV-3 with an IO-360 A1B6 up front, .040 forward fuselage skin, single .032 top wing skin, RV4 empennage, longer landing gear, fastback.
From talking to the owner of the one currently in Barnstormers, there were only five ever built. He flies it regularly and touted excellent performance and speeds comparable or exceeding the HR2 he flies alongside regularly. He has flown the F-1 Rocket and says the HR-1 is much lighter in pitch and slightly less in roll, almost Pitts behavior. Most Rockets are nose-heavy but apparently the HR-1 is better balanced. Climb apparently is spectacular, surpassing even the F-1. Having owned a 300HP HR2, that's impressive. (not quite the F16, but what is:))

John Harmon doesn't use this site but does monitor the Matronics Rocket list regularly. Most of the Rocket guys are there as well. www.matronics.com

Good Luck!
V/R
Smokey

PS:You can also call him, I have his cell# if you want to email me offline.



The few, the proud...
 
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Rocket Mailing List

Smokey, Tom,

thanks for that - as per Smokeys advise I have put a post on the Rocket Mailing list (which John Harmon seems to visit normally) with my questions however still all input is welcome.

Best, Heinz
 
Smokey, do you know the reason for the larger empennage ??

One reason I can think of is to get balanced elevators. I've talked enough with Van about the flutter limit testign on the original (and still standard) non-balanced -3 tail feathers, and I sure wouldn't want to take it very far above the design redline....simply because it hasn't been tested much above that.

With the IO-320, it WILL exceed redline in level flight. With a 360? Yeah....I'd want a different tail....:eek:
 
Balancing act...

Larry,

Paul is spot-on. The stock RV3 Horizontal and Elevator aren't counterbalanced. That was one big improvement on the Ah Vee Four. The counterbalanced elevator for high speed is crucial according to my Aerodynamics 101 book. It says "Aircraft control surfaces above 200 Knots are highly susceptible to flutter". That's good enough for me. With an Angle valve IO-360 out front and the claims of "200 knots easily attained in level flight", it's needed.

Having had a trim tab "buzz" in my RV4 at high altitude and high TAS, it's ain't fun. I even wrote a blurb about it, posted in the RV8R several years ago. All that said, if I had the money right now I would buy it!

V/R
Smokey



My favorite RV-3 photo, from down unda...horizontal stab clearly visible.
 
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thanks for the info - seems I have found the MTOW

Hi,

thanks for the info re the tail indeed. I seem to have found the MTOW as it was listed in one of the accident reports of N455DB to be 1500lbs. However just one source and for the time being no feedback from John Harmon or the Rocket mailing list so far.

If anyone has more information - appreciated.

Heinz
 
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