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HRII Engine Air Intake

andoman

andoman

Well Known Member
I'm wrapping up my HRII project. It has the standard P-51 "smile" intake on the cowl. Making it function appears to be more work than a fresh effort.
My specific question is: has anyone used an off the shelf intake kit? James or F1 perhaps? Any others?
Ease of initial install and ease of cowl off/on are my goals.
I'll email Sam James and Vince, but I thought I'd get some opinions here first. I've looked through all the relevant threads and i know that this cat has been skinned many, many ways.
For owners of old school HR's with the original intake design, a few pix or tips would be GREATLY appreciated.

Dan
 
Flat top...

I adapted the more recent "flat top" F1 intake to my RV-7 back in 2011. I had to fabricate an airbox to hold the square K&N filter and then adapt to the Avstar fuel servo.

IIRC the change was worth about 1" rise in MAP. However, maintenance, cowl removal/installation became more difficult.

In hindsight, I would have built a different airbox and larger access panel to connect the SCEET duct to the fuel servo.


Cheers.
 

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Did you create the intake mouth from scratch? Or did you glass on a basic shape that you got from Vince?
I've seen pixs of rockets that had the entire external intake portion removable (the forward half of the raw glass portion in your pix). I believe Dan H has such a setup on his -8. Could you have incorporated that feature into your design and solved your cowl removal/install difficulties?
 
andoman said:
Did you create the intake mouth from scratch? Or did you glass on a basic shape that you got from Vince?
I've seen pixs of rockets that had the entire external intake portion removable (the forward half of the raw glass portion in your pix). I believe Dan H has such a setup on his -8. Could you have incorporated that feature into your design and solved your cowl removal/install difficulties?
Click to expand...

I got the shape from F1Boss...

I should have made the entire bowl removable -- #8 screws or similar along the sides, etc.
 
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Do 1/4 turns. Perfect application, fast on and off.

Airbox hangs between the intake ring and the servo mouth on rings cut from reinforced silicone hose.
.
 

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DanH said:
Do 1/4 turns. Perfect application, fast on and off.

Airbox hangs between the intake ring and the servo mouth on rings cut from reinforced silicone hose.
.
Click to expand...

Hi Dan,
Is that an alt air door on the top of the filter box?
 
F1 Rocket said:
Hi Dan,
Is that an alt air door on the top of the filter box?
Click to expand...

Yes. It's spring loaded, and starts opening automatically when pressure drop across the filter element exceeds 3" H2O. At 1440 PPH flow, a completely blocked filter results in a carb loss of 6.2" H2O with flow working against the spring. That's only a wee bit more than pulling filtered air with the door shut.

Opening the door manually reduced the loss to 5.7", not enough improvement to make a manual alt air worthwhile...and the spring loaded door requires no action from this tired old meat servo.
 
Vince got back to me right away and said that his F1 intake would take "significant surgery." Still waiting to hear back from James Aircraft.
Thanks for the replies and the photos of the excellent workmanship.
 
Dan,

You can see the surgery that Brian Decker did above. Yours might be similar, but possibly a bit less on an HR2 cowl.

BTW, James Aircraft will just send you to me if it's Rocket parts youre needing. They are a long time supplier.
 
Thanks! Exactly the info I was looking for.
I discovered that the filter box I have is a James unit (for a conical filter). The "smile" transition from the box to the cowl is impossibly ill fitting. I'm going to make one attempt at hacking and glassing and then I'll punt.
Thanks again.
 
Let me see….

Might have a chin scoop with aft belly upstairs - if not, Jimmy will have one or will make one for you. Alt doors are not too hard to make…
 
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