What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Giant student, looking for CG validation

A

aerialsasquatch

I'm New Here
Hey y'all! I'm a student pilot who has the (usually fortunate) current misfortune of also being 6'9" (and around 300lbs). This makes CG and MGW calculations for a lot of planes that I would love to love...a bit of a one sided relationship.

The RV-8 in particular has really stolen my eyes, and fits everything I'd want in a mission. Speedy, great range, fun high ceilings, aerobatic, and seems to have the ability (especially with potential finagling of seat angles and panel re-structuring) to accommodate my height super well.

W&B are a bit more suspect.

For example, I've grabbed a couple POHs from users who were kind enough to post to do some testing of W&B, and they don't look great, especially on the MGW portion.

For example, the attached (using numbers from Burke's N113DU POH) shows just myself, full fuel, and the pax, with zero baggage, and already we're over the recommended MGW and also sitting pretty far aft in the envelope (though within limits). Forward baggage helps (but not a ton) on the CG, but only makes the MGW violation even worse.

I really want a plane that doesn't always have an empty backseat, and I'm curious what experiences other tall and/or heavy pilots have, as well as the experience of others with different engines and that impact on MGW and CG.

For reference, the above numbers I used as a reference were for an RV-8 with a Lycoming YIO 360 M1B 180 HP.

Also, if anyone ever finds themselves in the greater Charlotte, NC area, give me a shout! I'm always looking for folks to meet up with.
 

Attachments

  • 2023-06-17_19-35-58.jpg
    2023-06-17_19-35-58.jpg
    75.6 KB · Views: 97
Note that the standard fuel capacity of the RV-8 is 42 gallons, and your example uses 52 gallons.

If you limit your fuel to 30 gallons and no baggage, my RV-8 would accommodate a 212 pound passenger with a 300 pound pilot:

i-BNgKTQr-L.jpg

Note that for most RV-8s (and other Van's models), the cg moves aft as fuel is burned. In the above example but with zero fuel, the cg would still be ahead of the aft cg limit (at 85.98").

Also note that the seat and support structure may only be designed for 240 pounds, but that has not stopped heavier pilots and passengers from flying. The RV-14 may have been designed for heavier pilot and passenger weights. Check with Van's.
 
Last edited:
Thanks for all this info! The 52 was a mistake, good catch. This is certainly "brushing up on the edge", it looks like with 30 pounds of fuel in this example it also just becomes viable relative to MGW, and within limits (though still very close to aft).

It's starting to look like "you'll probably be heavy, and definitely be less responsive due to being aft" might be the story of my experience in an RV-8 with a pax. And will come with lessened range, which isn't the end of the world given my expected spread of range in my mission, but as a numbers junky I have to say hurts to think about, at least right now.

Out of curiosity, what engine are you using? I'm also curious how much the MGW has to do with airframe, landing gear, and "ability to pull", respectively.

I'll have to take a look at some of the other options, though I'm nervous that:
a) a 4 seater will have very similar problems
b) I'll be able to take pax more comfortably, but will have to make them ride in the backseat instead of co-pilot.

Also, your spreadsheet has inspired me to new heights!
 
I'm having a sneaking suspicion that in order to not be flirting with the edge at any given moment, I may need to also start exploring the world of Bearhawks, etc. It's a painful sacrifice in speed and range (and no aerobatics), but with usable loads in the 1200lb range might be a sacrifice I have to make if I ever want to take a friend with anything other than the shoes on our feet.
 
First things first, see if you can even fit into the cockpit. A friend was considering a Lancair ES but he cannot sit in one without his head hitting the canopy.
 
blaplante said:
Not to mention you may have a big headroom problem.
Click to expand...

That's a very good point, but usually I don't struggle in the headroom space, I'm actually a fairly small torso height (relative to my size at least), it's legs that get me. In a C182, I'm actually sitting with the seat not all the way down (nor all the way back, which I found surprising) and have plenty of headroom.
 
Tommy123 said:
First things first, see if you can even fit into the cockpit. A friend was considering a Lancair ES but he cannot sit in one without his head hitting the canopy.
Click to expand...

Absolutely, the trick is finding one local-ish, or making a voyage myself once I make a few friends. Even better if they're tall(ish) as well, to get the best possible feel.
 
aerialsasquatch said:
Thanks for all this info! The 52 was a mistake, good catch. This is certainly "brushing up on the edge", it looks like with 30 pounds of fuel in this example it also just becomes viable relative to MGW, and within limits (though still very close to aft).

It's starting to look like "you'll probably be heavy, and definitely be less responsive due to being aft" might be the story of my experience in an RV-8 with a pax. And will come with lessened range, which isn't the end of the world given my expected spread of range in my mission, but as a numbers junky I have to say hurts to think about, at least right now.

Out of curiosity, what engine are you using? I'm also curious how much the MGW has to do with airframe, landing gear, and "ability to pull", respectively.

I'll have to take a look at some of the other options, though I'm nervous that:
a) a 4 seater will have very similar problems
b) I'll be able to take pax more comfortably, but will have to make them ride in the backseat instead of co-pilot.

Also, your spreadsheet has inspired me to new heights!
Click to expand...

My RV-8 has an YIO-360-M1B and a Hartzell Blended Airfoil constant speed prop.

Although generally speaking, the heavier the airplane is the less responsive and sluggish it is. But for the tandem seat airplanes, as the cg moves back the stick-force-per-g lessens considerably, and near the aft cg the RV-8 (and RV-4) becomes sensitive and more prone to PIO at final approach speeds. One must take care and be aware of that tendency.

Regarding headroom, the RV-14 was designed for larger pilots and passengers (size and weight) and would offer more headroom that earlier RV designs.
 
Ours is down with the engine out for IRAN. You are welcome to come any time and try it on. I'm not that far from you. Just PM me and we'll get together.
 
aerialsasquatch said:
I really want a plane that doesn't always have an empty backseat, and I'm curious what experiences other tall and/or heavy pilots have, as well as the experience of others with different engines and that impact on MGW and CG.
Click to expand...

I'm just under 6'5" and weight has varied from 210-280. My 8A is 1015 lbs empty with the empty CG at 79.6. This with an O-360, catto three blade and minimal day-VFR panel, no lights, no gyros (the easiest way to save weight when building is to not put stuff in).

The key to being able to load bigger passengers is to use ballast in the forward baggage compartment. If I put 50 lbs up front I can then fly a 220 lb passenger to empty fuel or a 240 pounder to half fuel and stay ahead of the aft CG.

Using 300 lbs in the pilot seat I could still get up to 200 lbs in the back as long as the ballast is used. Can't get to full fuel and stay under gross, but can get up to 35 gallons on board. Can't take a heavy person for a long cross country with much luggage, but can give a friend a ride.

Aerobatic weight will be just you and gas. It is the same for me, I could take a smaller (up to 120 lbs) passenger and stay in the aerobatic envelope, but don't have anyone that small who wants to get upside down with me.

Regarding the height, I'm long in the torso more than legs, and I fly with the rudder pedals full forward and a 3" cushion or slightly thinner seat chute. With the 3" cushion knees will just barely hit the bottom of the panel when on the brakes. Have enough clearance above my head I don't hit when pushing negative Gs.

You would want the "tall pilot option" which moves the top of the front seat back a bit, and then to move the bottom a few inches back as well. Others have done that for more leg room.

Do see if you can find one to try on, fit is a very personal thing.
 
Almost all my test flying was at MTOW of 1800 lbs, IO-360/Hartzell 2-blade metal prop/FM 200/PMAGS and the plane flew and handled great. Obviously I didn't do any aerobatics at this weight, but the performance was excellent.

When I take one of my girls on a trip you can be sure I'm right at MTOW.

Ways to increase payload in the RV-8 are to use a LIFEPO4 battery on the firewall (EarthX), composite prop (many options), aluminum gear legs (Ken Krueger), small gear-driven alternator/generator (Monkworks/B&C/Hartzell), and forgo the heavy leather interior.

If you feel you need more power, consider a hopped up parallel valve 360 like the IO-375 that some engine builders offer (Aero Sport Power). The angle valve is heavier.
 
Your welcome to come sit in mine to try it on. I have several seat bottoms for different missions you can try on. Not far from you.
 
You don't mention budget or goals, so here is an idea - RV-10. Greater headroom and Much greater leg room than the other planes and feel that mods could be made to lower the rear of the seat to increase that. It is an adjustable seat back, so that wouldn't affect the sitting angle. Weight is a total non-issue, though it may require some ballast in the rear when the rear seats are vacant. No aerobatics and the sporty feel of the 8 is gone, but still a very pleasant flying plane with good control response. IMHO, it is the best platform to comfortably fit a man of your size.
 
Last edited:
I'll be the black sheep here... (as usual!).

If you find the cockpit space in an RV to be too tight, take a long, hard look at a Glasair Sportsman. Its cockpit is easily able to handle larger aircrew.

I have personally found no problem accommodating me (5'9", 200lbs) and my friend who is 6'8" and somewhere north of 275lbs in our Sportsman. This is done in relative comfort, as in comfortable enough to fly a multi-hour leg together.

Useful load and centre of gravity are not concerns in the Sportsman under this loading condition. With the two of us and full (50gal) fuel we still had something like 125lbs available for cargo. One wouldn't want to load heavy cargo far aft in the cargo hold in this loading scenario; heavier things go forward, lighter things go aft in order to protect the aft C of G limit. Fuel burn causes the C of G to move forward so worst-case loading is on takeoff rather than landing.
 
You must log in or register to reply here.
Back
Top