Measurement needed from flying 4s

I have been working on my RV4 kit for several years down here in Australia and was hoping that one or more of the flying owners may be able to help out with a particular measurement. I will be fitting a Velo rally car seat (similar to John Johansen's round the world RV4) and wish to position its height for optimal three point visibility. However, as it will be some time before I am able to hang the engine and fit the cowls, seat height for three point visibility becomes quite difficult to estimate. What would be enormously helpful would be to know how far the highest point of the cowl sits above the fire wall relative to the horizontal. This could be easily measured by siting a spirit level (we call them bubble sticks) on the highest point of the cowl when the aircraft is sitting on level ground, and extending this line back to a point directly above the fire wall. I could then use this datum point to estimate three point visibility over the cowl. Of course if I had access to a long legged RV4 anywhere near by I would simply take this measurement myself. I am guessing it may only be an inch or two but without an actual aircraft to measure I simply don't know. And yes, we can of course add this building complication to the long list of problems we encounter whenever we make changes to the plans, (ie fitting a custom seat, moved aft for a tall pilot = changes to roll bar position= changes to canopy frame and on and on it goes...).Thanks in advance to those of you who might take the time to help me out. I only wish I had thought of this when I visited Oshkosh last year and saw so many wonderful examples of the RV4.
Thanks again,
Darren

I took a look at my long gear RV 4. The highest point is 1 1/4" above the firewall and is 14" behind the front edge of the cowl.

Don't create a problem,

Hi,

May I suggest you are going about this in a way which could create you problems. The max seat height you can have is governed by the length of your body from your bottom to the top of your head with headset and how they fit under the canopy.

Oregon aero will make a seat to fit your body size and they are very comfortable. I am 5'08" with 30 inch inside leg.i have two crushed discs so lumbar support is essential for me. With the Oregon seats my 4 is the most comfortable aeroplane I have sat in.......ever!. The view over the nose is no problem at all. I have about 1 inch of clearance above my headset to the canopying?

Bottom line is that the max seat height is governed by that canopy so you need to measure from that down to the seat pan. Work out your upper body length including head sets plus one inch of clearance, the deduct this from the first measurement and you know the max height for your seat. Three point viz is not an issue if you do this.

I have no connection with Oregon apart from being a very happy customer. They are expensive but flying without pain is worth every penny.

Thanks

Thank you very much Mark. That is exactly the information I need. I greatly appreciate your help.
In relation to creating building problems Steve, I couldn't agree more. Unfortunately, the problem has already been created in my long legs and short upper body. In order to fit in the 4 comfortably I need to move the seat and roll bar back significantly which lowers my visibility further by changing the angles. Whilst I could still adapt the usual seating as you suggest for the simplest solution, the Velo seat suits my body shape perfectly and having flown in them before I love the way they add to that "wearing" the aeroplane feel.
Thanks again for your input and any further measurements confirming Mark's numbers would be greatly appreciated.
Darren

If you are woried about visibility on the ground, you will have no problems. You will see around the nose easily and it is only the start of the T.O. roll and the flare that there is any limitation. The RV4 is not a bad taildragger to see out of. I will get those measurements if I get to the strip tomorrow.

I took a couple of measurements today. The highest point of the cowl is 550mm back from front of cowl and is 1550 from ground level. The Longeron below eye location is 1200 from GL. Sorry i didn't get firewall height, but it is just below line of sight from top of cowl. My eye location is 190mm below the top of canopy and I can see the horizon at cowl cheek level, it is only the curved centre portion of the cowl that obscures forward vision and by moving my head side to side I can make that a very small area.
I was concerned about visibility when I was building the RV, but I have far less in my Corby Starlet, so it seems that it is possible to live with anything. Those old Percival Gulls must have been horrendous.

Thanks

Thanks Ian. I also currently fly a Corby and forward visibility is at a premium for me too. I am sure the 4 will be much better, however as I am mounting a non-adjustable custom seat much further aft than as per plans I want to maximise visibility. Thanks again for the measurements.....Darren

Darren. I built an aluminium seat frame from memory about 75mm to 50mm high for the pilots seat and have 35mm of conforfoam seat on that. that got me up quite high enough. The frame has near vertical stiffeners under the pan, all designed by me to collapse in a serious vertical impact. It is a lot better than just sitting on the floor as per the design.

Hi Ian. The Velo rally car seat I will be using will also take a bit of custom mounting for correct positioning however it should be well worth the effort. They are extremely comfortable and fit me perfectly. Cheers, Darren