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RV-7A W&B / Nose Wheel Weight

Craw

Active Member
I am considering installing the angle valve IO-360 on an RV-7A (with the new D1 engine mount and elastomer nosewheel config from Vans) as well as an MT prop. The reasons I'm leaning towards this configuration are:

- I intend to install a BRS chute system and the heavier engine will help bring the CG forward (BRS chute systems moves it aft ~1").
- I also intend to use the aircraft for IFR whence the chute install

- The Counterweights in prop and crank allow for better control during light aerobatics. The MT is also a little lighter than other props and of course has the counterweights.

I am curious if anyone has built this or a similar configuration before and if so what did your nose wheel weights come in at? I am open to other engine and prop configurations/suggestions.

As always thanks for your feedback.

Cheers,


Phil

Just about finished the tail kit for an RV-7A and expecting a QB fuse in wings sometime this fall/winter.
 
I don't have that setup but seem to recall the angle valve engine is around 30-35 lbs heavier than the parallel valve. That and the parachute won't leave much for baggage with two 200 lb pilots and full gas. That said, you get to decide the max gross weight, as some have, and up it to 2000 lbs.
 
Thanks much for the response, I am a lightweight weighing in @ 140lbs soaking wet and my better half is under 120lbs. I'm not overly concerned about gross weight but I am concerned about the nose wheel weight limtiation.

Cheers,

Phil
 
I’m not sure how much the chute system weighs, and assuming it is built into the baggage area, I think you may need the extra weight up front in order to maintain practical balance numbers, especially if you use a composite prop. Otherwise you’ll often be at the aft balance limit or beyond.

I might consider an O-360 mounted on a 0-320 engine mount which pushes the engine and prop’s weigh further forward. Ask Vans before making any such changes to the design (including the chute system).

Make yourself a spreadsheet and play with the weights and you will see what I mean.

As an example, my RV7A with (I)0-360 180HP, Hartzell CS prop, slider canopy, full interior and IFR panel currently has an empty weight of 1236lb at 81.1 inches of datum. I’m always operating near the aft limit when carrying baggage and average sized passenger.

Bevan
 
If you are going with the new nose gear design that Van's came out with like it sounds, they removed the nose weight limit that is in the plans. Although one would not want to get too carried away...
 
Agreed and thanks All. The BRS Chute system weighs about 42lbs and BRS Chute systems provides some good information on installation in RV-7 &9's.

I have drafted up a W&B spreadsheet based on my best estimates using acutals from other aircraft with a similar engine (but not prop or chute).

I will post the spreadsheet once I find somewhere to upload it that can be shared.

Cheers,


Phil
 
One more thing to consider, Phil.
You mentioned light aerobatics. Remember that Van's recommends a 1600 lb max weight for aerobatics. You'll get there quickly with your proposed setup.

Have fun, fly good, don't suck! :cool:
 
Hi Phil
I’ve got the angle valve engine on a 7a with the old nose gear setup. I’ve got a whirlwind constant speed prop with a sky dynamics flywheel and an earthx battery and my nose wheel weight is 306lbs.
I hope this helps
 
Thanks Much CMore! May I ask what ignition and how many heat muffs you have?

All,
Here is a link to the W&B spreadsheet I drafted based on one of the heavier RV-7A's I could find. I used a calculator to add in the BRS system to the empty weight. In other words the link to the sheet below already includes the chute in the empty weight CofG.

Please let me know if you find anything wrong or if you have some comparable data based on a similar configurations: 7A: Angle valve 360, CS composite prop.

https://drive.google.com/file/d/1b0tN0A5ZhwJZ0_Rysn3e1IrHSV0IlW7y/view?usp=sharing
The sheet was created in excel so when posting on google drive it buggered up the envelope titles but green is Aero, blue is Utility and red is Normal.

All the best,

Phil
 
Check that really good! The arm for the BRS is quit long!

BRS just made an installation ... and did not calculated the shift in W&B.
 
Last edited:
I updated the sheet a little and have included some of my assumptions below:

Based on the following RV-7A calculator (https://www.google.com/url?sa=t&rct...-Balance.xls&usg=AOvVaw1rXLUL79lqA1dhi1bPjFRx)

I am using a conservative nose wheel weight for my proposed configuration of 315lbs (based on CMORE similar 307lbs) and left and right wheels at 450lbs each including the BRS chute. I get an empty weight of 1215 and a CofG og 79.7 to which I add an inch aft as per BRS recommendation which brings the CofG empty weight to 80.7.

Looks like I can do solo aero and with a passenger and full tanks I am limited to 65lbs in the baggage compartment.
 
Hi Phil,
I've got standard mags with just one heat muffler, no need for any more in Sunny Australia :)
Just FYI, with the parachute in the back your nose wheel weight is likely to be less than a comparatively built machine.
Cheers
 
Good point, thanks much Cmore! I am still years away from getting to that stage of the project, however it looks like my desired configuration will work, time will tell.

All the best,



Phil
 
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