Gee don't be be shy
glenmthompson said:
Haha, well....I really did not want to start this conversation, as it is an open invitation for George to come in and patronize us all....but, since you ask,: Glen PS, soooo, has anybody tried this RV 7 mount/cowl thing yet/before?
Glen, I would never patronize you. Clearly you know things I never heard of? Can't we discuss this without the personal comments.
glenmthompson said:
......bottom of the firewall where bottom skin and firewall join? Yep, you guessed it H U G E drag there........."
Non aerodynamic, round engine mount tubes? BIG DRAG........"
REALLY! That is fascinating. The lip at the firewall and round engine mount tubes are H U G E drag items. I am not saying they don't count, but it seems like these items, to me, are really minor, sorry no offense.
How do you measure this drag?
Has anyone used an aerodynamic shaped tubing engine mount?
Has anyone verified a firewall skin join is the prime reason one RV is faster than another?
I do agree every little bit counts.
However back to the thread, First I did not know there was a big difference between the RV-6/7 cowl and engine mount. However if the RV-7 is longer
I don't see that slight increase in cowl length helping that much as many have echoed. You say Van's Engineering (Richard VanGrunsven?) said this. I am just curious, no offense.
A longer nose is more aerodynamic, but a prop extension at the front gives that "pointy" effect better than just hanging the engine further off the firewall, which is what I gather from reading this thread? Some clever internal baffles would help "turn the air" better. All the 90 degree turning happens in the upper plenum. The lower cowl (plenum) is slower air and has lots of room to line back up with the free air steam. There are tubes and stuff in the way, but 2" will not make any differnce here. It's just my gut feeling, no offense.
A longer RV-7 engine mount/cowl would not hurt, but than with a RV-6 you could run into Fwd CG issues with a heavy engine. I agree a light wood prop, like the Catto would help offset this weight and balance issue. Less DRAG? I don't get it. No offense; I could be wrong. The longer you make the plane the more you also increase the "wetted area" drag.
Pops: Without patronizing either of us, teach me about Catto props. You brought it up. I want to hear more; From flight test (you probably don't want to hear this)
Sensenich was the fastest along with the Hartzell BA c/s prop. It would be great to have a actual side by side fly off with a Catto vs a Sensenich.
I hear these "fastest claims" but when the side-by-side test comes around the claims don't match the reality. As far as cost, the Sensenich is about the same money as the Catto. On a RV-7 you need the weight on the nose. I am not putting your Catto down, but we need to talk without emotion. If you have some facts that the Catto is "fastest", that would be cool. People read this and need the facts to make their decision. I hear good things about Catto and only heard of one in flight failure.
Catto (fiberglass wrapped wood) has all the cool attributes over metal you stated: lighter weight and no harmonics. As far as "corrosion" you DO have have "erosion" and material breakdown, as with any bonded composite wood prop. However, like all props they can be refinished or overhauled, but nothing last for ever. Metal props are quite durable. With normal care metal corrosion is not an issue to achieve the props full and long service life.
I still say with out being patronizing, for the money you can't beat the Sensenich. For top overall performance and value you can't beat the Hartzell BA prop.
If you think that is patronizing, sorry it's just my opinion, there is a difference. You are entitled to yours. Obviously you are a big fan of Catto props, which is cool they are great I am sure. Good luck with that.
Cheers George