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-   -   RV-7A W&B / Nose Wheel Weight (https://vansairforce.net/community/showthread.php?t=186222)

Craw 08-26-2020 07:31 AM

RV-7A W&B / Nose Wheel Weight
 
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.

Raymo 08-26-2020 12:42 PM

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.

Craw 08-26-2020 01:02 PM

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

Bevan 08-26-2020 01:22 PM

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

jcarne 08-26-2020 02:17 PM

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...

Craw 08-26-2020 02:50 PM

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

scrollF4 08-26-2020 04:35 PM

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:

Cmore 08-27-2020 02:28 AM

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

Craw 08-27-2020 06:14 AM

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/1b0t...ew?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

swisseagle 08-27-2020 07:32 AM

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.


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