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  #1  
Old 06-07-2011, 12:10 AM
rentiap rentiap is offline
 
Join Date: May 2011
Location: In my body
Posts: 13
Default About to build a Harmon Rocket I

Greetings:
I am about to pull the trigger and order the parts to build what I believe to be "essentially" a Harmon Rocket I using a RV-3b instead of an RV-4 for the foundation.

((actually this may just be a hopped up RV-3 with mods))

I have only found 2 pictures and what looks like what the late Pete Albrecht (sorry to hear that he has passed) was flying in the video that is posted of Harmon Rocket I's.

I prefer the slimmer front cowl of the RV-3 with cheeks, with fast-back rear turtledeck,
than the wider squared out look of the Rocket II, and am going to stay with a lighter weight stroked out IOX-340S (185-190 horse) apposed to going with the heavier IO-360, or the HR-III and much heavier IO-540.

I would like to shoot for an empty weight of 775 lbs, as apposed to the empty weight of 1080 lbs of the Rocket III.
I have not found very much info on the few HR-I's that have been built.

I am figuring that I will be needing to setback the cockpit for CG.(like the HR-III)

Does anybody have any information that could help in figuring out this setback before I actually start ordering the parts?

Any discussion and info is appreciated.
Thank you,
Geodfreid.
  #2  
Old 06-07-2011, 05:03 AM
Tom Martin Tom Martin is online now
 
Join Date: Jan 2005
Location: Ontario, Canada
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Default

Although it looks like you have discounted the RV4 as a foundation I still think that a clipped wing, single place RV4 would give you a more versatile aircraft. By that I mean you would be able to carry some baggage and have more engine options. It would retain the cowl cheeks that you like and with a raised turtle deck with seating towards the rear it would look hot.
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  #3  
Old 06-07-2011, 06:26 AM
HFS HFS is offline
 
Join Date: Aug 2009
Location: Lemoore, CA
Posts: 80
Default Rocket I

John Harmon and I went to high school together and my Rocket II is S/N 2 and his prototype is S/N 1. I'm not sure I remember the exact sequence of the Rocket I's evolution, but John did build two of them concurrently - one for the "sponser" - Jim Irwin (not AC Spruce guy), and one for himself as payment. This was back in the early to mid 1980's. They were essentially a standard -3 with a "pumped up" motor and a raised turtleback, I don't recall any change of seating location for CG reasons as all the parts and pieces were installed in the original locations.

You may or may not be aware, but Van made a drawing of the aft raised turtleback for the -3 back in 1984 - "Fuselage - Aft Fastback" Drawing #22, with upgrades by Sid Goldin in June of 1997. It provides the "callout" for the parts needed to turn a standard 3 into a razorback version. I have one of the few copies that are still floating around out there in space.

I am currently about 30% through my own -3 build, and am incorporating some of the upgrades that Van integrated into the design of the -4. I built (and flew for 15 years) a 4, and have noted the benefit of these changes from that airplane. When finished this airplane will feel like a single place RV4, but in the confines of a -3 "body".

If you want (need) any additional info regarding the above - give me a call at (559)816-0433.
  #4  
Old 06-07-2011, 08:47 AM
mvs163 mvs163 is offline
 
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Location: Southern Ontario
Posts: 100
Default

I have 100hrs on my -3 and its a great airplane. Current project,a single seat, clipped wing, 4 cylinder -4.
I've used the stock -4 motor mount and gear legs and the fwd fuse is the stock width at the bottom but 33 inches at the top. The upper longerons are straight from the seatback to the firewall. Uing the stock "cheeked" cowl as a start and "most" of the cheek will blend into the wider firewall. I believe the H1's were similar, keeping(hopefully) the slender/less blunt/faster stock nose.
Using the stock rear seat back position, the HR's are about 4" further back.
About 20' span,late model elevator balances with clipped stab,revised aft fuse bulkhead that matches the rudder width, a lot more room for systems, battery on the firewall and a C/S prop makes the C of G work and you've got the deeper/stronger spar of the -4.
My -3 is 760lbs so aiming for 900lbs this one.
Mike
  #5  
Old 06-07-2011, 09:37 AM
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JonJay JonJay is offline
 
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Default I would consider the CC-340 if they will sell you one.

Cub Crafters has done a lot of work on the 340. They pump it up to 180hp and although they put limits on the duration and allowable RPM's at a given altitude, I believe it is striclty to keep the SS in the Light Sport category. I believe you could run that engine all day at its fully rated HP.
They have taken a lot of wieght out by designing their own light weight fabricated sump, electronic ignition, and probably a few more things.
I do not beleive you could find a better lower wieght engine.
There was some talk about making this engine available to the public. I am not sure if that talk ever went forward or what the ultimate price of that product would be. CC is not a low price industry leader....
We have the good fortune of having Randy (Tardy/Splash) Lervold working for them. Nobody knows RV's like Randy and he would be the one to start with if you wanted to pursue this further. He may even still lurk on this forum.
You can take the pilot out of the RV but you can't take the RV out of the pilot. Ha!
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  #6  
Old 06-07-2011, 11:45 AM
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rocketbob rocketbob is offline
 
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Sounds like you just want a fastback -3. No need to stretch it, as there is plenty of room n the cockpit. A friend of mine built one and I flew it a few times...what a fun, nice flying, economical airplane. He did the raised turtledeck per the plans mentioned above and built a custom canopy frame and had a bubble blown for it. Sadly he crashed it and and eventually died from his injuries.
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  #7  
Old 06-07-2011, 11:33 PM
rentiap rentiap is offline
 
Join Date: May 2011
Location: In my body
Posts: 13
Default Hmmm??? to b-4? or to-3b?

Thanks for your comments Tom;
I have not completely discounted using the -4 for the foundation for this project.
There are many considerations that must be considered.
And of course I don't want to limit myself to engine options.
Also if I use the -4 as the foundation there is also the option for larger fuel cells.
And with the clipped -4 wing possibly a stronger wing. then the -3b wing.
Which is a better airfoil?
The thinner 23012 of the -3b with new internal structure @ 19ft 11inches?
Or the slightly thicker 23013.5 -4 clipped to 20 ft.?
Does anyone have an opinion on which is the stronger more efficient wing?
Lots to consider here.
Cheers,
Geodfreid.

Quote:
Originally Posted by Tom Martin View Post
Although it looks like you have discounted the RV4 as a foundation I still think that a clipped wing, single place RV4 would give you a more versatile aircraft. By that I mean you would be able to carry some baggage and have more engine options. It would retain the cowl cheeks that you like and with a raised turtle deck with seating towards the rear it would look hot.

Last edited by rentiap : 06-08-2011 at 10:55 PM.
  #8  
Old 06-08-2011, 12:04 AM
rentiap rentiap is offline
 
Join Date: May 2011
Location: In my body
Posts: 13
Default

Hi David:
I am not sure I could have asked for someone any closer to knowing about the HR-1 then you. I was hoping for someone like you to reply with first hand knowledge. I am sure I will be contacting you in the very near future.and hope to bend your ear a bit.
I was not aware that Van had "made a drawing of the aft raised turtleback for the -3 back in 1984 - "Fuselage - Aft Fastback" Drawing #22, with upgrades by Sid Goldin in June of 1997". And provides the "callout" for the parts needed to turn a standard 3 into a razorback version.this is great news
I have contacted John Harmon ,and he stated that the rear bulkheads he makes for the rocket II will work to make the raised turtleback if used on the -3. I am sure it wouldn't be just a slip in and go,,,some massaging I am sure would be required,,,But that's Kewl.
Thanks,
Geodfreid


Quote:
Originally Posted by HFS View Post
John Harmon and I went to high school together and my Rocket II is S/N 2 and his prototype is S/N 1. I'm not sure I remember the exact sequence of the Rocket I's evolution, but John did build two of them concurrently - one for the "sponser" - Jim Irwin (not AC Spruce guy), and one for himself as payment. This was back in the early to mid 1980's. They were essentially a standard -3 with a "pumped up" motor and a raised turtleback, I don't recall any change of seating location for CG reasons as all the parts and pieces were installed in the original locations.

You may or may not be aware, but Van made a drawing of the aft raised turtleback for the -3 back in 1984 - "Fuselage - Aft Fastback" Drawing #22, with upgrades by Sid Goldin in June of 1997. It provides the "callout" for the parts needed to turn a standard 3 into a razorback version. I have one of the few copies that are still floating around out there in space.

I am currently about 30% through my own -3 build, and am incorporating some of the upgrades that Van integrated into the design of the -4. I built (and flew for 15 years) a 4, and have noted the benefit of these changes from that airplane. When finished this airplane will feel like a single place RV4, but in the confines of a -3 "body".

If you want (need) any additional info regarding the above - give me a call at (559)816-0433.
  #9  
Old 06-08-2011, 12:07 AM
rentiap rentiap is offline
 
Join Date: May 2011
Location: In my body
Posts: 13
Default

Hi Mike:
Sounds like you might already be doing just what I was thinking of doing,,,Do you have any Pics of this fine project?

Quote:
Originally Posted by mvs163 View Post
I have 100hrs on my -3 and its a great airplane. Current project,a single seat, clipped wing, 4 cylinder -4.
I've used the stock -4 motor mount and gear legs and the fwd fuse is the stock width at the bottom but 33 inches at the top. The upper longerons are straight from the seatback to the firewall. Uing the stock "cheeked" cowl as a start and "most" of the cheek will blend into the wider firewall. I believe the H1's were similar, keeping(hopefully) the slender/less blunt/faster stock nose.
Using the stock rear seat back position, the HR's are about 4" further back.
About 20' span,late model elevator balances with clipped stab,revised aft fuse bulkhead that matches the rudder width, a lot more room for systems, battery on the firewall and a C/S prop makes the C of G work and you've got the deeper/stronger spar of the -4.
My -3 is 760lbs so aiming for 900lbs this one.
Mike
  #10  
Old 06-08-2011, 12:19 AM
rentiap rentiap is offline
 
Join Date: May 2011
Location: In my body
Posts: 13
Default Is there a more efficient way?

Hey Jon: Thanks for the heads up on Cub Crafters.
Maybe Randy will give his 2cts worth?

Should I be restricting myself to the smaller size of the stroked out IO-340?
What if I decide to go for 200 HP.
What would be the lightest most efficient way to make 200+HP?
Just more questions ?

Cheers,
Geodfreid.

Quote:
Originally Posted by JonJay View Post
Cub Crafters has done a lot of work on the 340. They pump it up to 180hp and although they put limits on the duration and allowable RPM's at a given altitude, I believe it is striclty to keep the SS in the Light Sport category. I believe you could run that engine all day at its fully rated HP.
They have taken a lot of wieght out by designing their own light weight fabricated sump, electronic ignition, and probably a few more things.
I do not beleive you could find a better lower wieght engine.
There was some talk about making this engine available to the public. I am not sure if that talk ever went forward or what the ultimate price of that product would be. CC is not a low price industry leader....
We have the good fortune of having Randy (Tardy/Splash) Lervold working for them. Nobody knows RV's like Randy and he would be the one to start with if you wanted to pursue this further. He may even still lurk on this forum.
You can take the pilot out of the RV but you can't take the RV out of the pilot. Ha!
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