DakotaHawk
Well Known Member
I had an interesting opportunity this week to form up with my friend David Mischke and his new BD5 for about an hour of flying. This is David's second BD5 - his first had the modified thicker airfoil which slows the stall down to about 75mph. This one has the original airfoil - stalls at about 85mph.
I was flying over Skagit/Bayview KBVS just to see who was at their hangar, when I heard David come up on CTAF announcing departure on RWY 28. We formed up in the air and flew out over the San Juan Islands.
Now, just for a little background... I only have about 30 hours on my RV-7. Since I'm fairly new at this high performance stuff, I'm still sneaking up on some of the performance issues. I've been flying my other plane at 85 mph for the past 10 years, so going fast is still, well, fast!
So as we head out over the San Juan's at about 140 mph, David says this is too slow for his BD5 and "can we bump it up a little". Well, "a little" turns into 190 mph! The IO-360 is purring and the islands pass by quickly under us. We flip over to the Islands CTAF. There is at least one airport, runway, or strip on just about every island in the San Juans. No Bridges. The only way to get here is by Ferry or airplane. With so many runways within such a small area, every airport uses the same frequency to promote better communications in a busy airspace environment.
We fly over Sammish Island, Guemes, East Sound (Orcas), Friday Harbor, Lopez, Center, Decateur, and several smaller islands, we headed back inland over Anacortes. A stop at Skagit/Bayview to make an adjust on David's aileron, and then we departed for a flight up the Skagit River valley.
As we passed Concrete (3W5), we saw light rain in the Darrington valley and decided to climb above the rain. We started at 2500' and climbed to 9500 to get on top of the clouds. A quick run using GPS for navigation (there's no landmarks up there!) to Arlington, where we found a hole and dropped back down into the muck.
We landed at Arlington (my home airport) to unwind a little bit, and after swapping tales about our escapades, David departed for home.
So here's the comparison---
Take off roll. RV-7 takes off NOW! OK, well, maybe there's 750' take off roll. The tail is flying after about 400', tires off the ground at 750', and then pull back on the stick for a climb at 100mph gives 2200fpm climb at sea level / 50*F. The BD5 has a pusher/Kawasaki (edit - Yamaha Nytro - not a Kawasaki)snomobile engine that winds up to 8500 RPM and a 2:1 reduction to the wood prop. The prop is only about 36" (edit - it's really 48"!), and has a huge amount of pitch so the take off roll starts slowly and uses about 2500' of runway. (Remember the stall at 85mph!) At about the time the BD5 lifts off, the prop is finally starting to bite and the little rocket begins to accelerate fast. Climb out on the BD5 is about 2000fpm initially, but the prop can't keep up, and sustained climbs are about 1200 - 1500 fpm.
Cruise. The BD5 is tiny! It's empty weight is about 550#. There isn't much room for anything other than the pilot and the engine. David says that he doesn't cruise at less than about 160mph minimum. 180mph is even better. He says that he feels like he's about to fall out of the sky at 140mph. At 190mph he's burning about 5.5 gph - My IO-360 was going through about 11.5gph. Because of the size and weight of the BD5, it's twitchy. It has to be flown 110% of the time. Every time we had to do a freq change, I scooted out away from David. As soon as he looked down at his panel to make freq changes, the BD5 was all over the sky! Partly, this was due to a heavy wing that David is still making adjustments to fix.
Aerobatic flight. David says that the BD5 is capable of a full range of loops and rolls. I didn't think to ask about stall/spin characteristics.
Landing. This is the weakest link in the BD5 story. David flies the pattern at about 110mph (edit - 125 - 130mph), and comes over the fence at about 100mph. Just like the RVs, the BD5 is so aerodynamically clean that it doesn't slow down very easily. The cruise prop doesn't provide any braking at all! So touchdown at about 90 mph and roll-out takes 2500 - 3000 feet of runway! This is compared to the RV-7 - over the fence at 85 mph, touchdown at ~65 mph, and less than 1000 feet of roll-out.
Due to the take-off and landing roll, the BD5 has to be very particular about the runway lengths it can fly into. If there isn't 5000' available, the pucker factor goes way up!
So, long story short, I'd rather fly my RV-7!
I was flying over Skagit/Bayview KBVS just to see who was at their hangar, when I heard David come up on CTAF announcing departure on RWY 28. We formed up in the air and flew out over the San Juan Islands.
Now, just for a little background... I only have about 30 hours on my RV-7. Since I'm fairly new at this high performance stuff, I'm still sneaking up on some of the performance issues. I've been flying my other plane at 85 mph for the past 10 years, so going fast is still, well, fast!
So as we head out over the San Juan's at about 140 mph, David says this is too slow for his BD5 and "can we bump it up a little". Well, "a little" turns into 190 mph! The IO-360 is purring and the islands pass by quickly under us. We flip over to the Islands CTAF. There is at least one airport, runway, or strip on just about every island in the San Juans. No Bridges. The only way to get here is by Ferry or airplane. With so many runways within such a small area, every airport uses the same frequency to promote better communications in a busy airspace environment.
We fly over Sammish Island, Guemes, East Sound (Orcas), Friday Harbor, Lopez, Center, Decateur, and several smaller islands, we headed back inland over Anacortes. A stop at Skagit/Bayview to make an adjust on David's aileron, and then we departed for a flight up the Skagit River valley.
As we passed Concrete (3W5), we saw light rain in the Darrington valley and decided to climb above the rain. We started at 2500' and climbed to 9500 to get on top of the clouds. A quick run using GPS for navigation (there's no landmarks up there!) to Arlington, where we found a hole and dropped back down into the muck.
We landed at Arlington (my home airport) to unwind a little bit, and after swapping tales about our escapades, David departed for home.
So here's the comparison---
Take off roll. RV-7 takes off NOW! OK, well, maybe there's 750' take off roll. The tail is flying after about 400', tires off the ground at 750', and then pull back on the stick for a climb at 100mph gives 2200fpm climb at sea level / 50*F. The BD5 has a pusher/Kawasaki (edit - Yamaha Nytro - not a Kawasaki)snomobile engine that winds up to 8500 RPM and a 2:1 reduction to the wood prop. The prop is only about 36" (edit - it's really 48"!), and has a huge amount of pitch so the take off roll starts slowly and uses about 2500' of runway. (Remember the stall at 85mph!) At about the time the BD5 lifts off, the prop is finally starting to bite and the little rocket begins to accelerate fast. Climb out on the BD5 is about 2000fpm initially, but the prop can't keep up, and sustained climbs are about 1200 - 1500 fpm.
Cruise. The BD5 is tiny! It's empty weight is about 550#. There isn't much room for anything other than the pilot and the engine. David says that he doesn't cruise at less than about 160mph minimum. 180mph is even better. He says that he feels like he's about to fall out of the sky at 140mph. At 190mph he's burning about 5.5 gph - My IO-360 was going through about 11.5gph. Because of the size and weight of the BD5, it's twitchy. It has to be flown 110% of the time. Every time we had to do a freq change, I scooted out away from David. As soon as he looked down at his panel to make freq changes, the BD5 was all over the sky! Partly, this was due to a heavy wing that David is still making adjustments to fix.
Aerobatic flight. David says that the BD5 is capable of a full range of loops and rolls. I didn't think to ask about stall/spin characteristics.
Landing. This is the weakest link in the BD5 story. David flies the pattern at about 110mph (edit - 125 - 130mph), and comes over the fence at about 100mph. Just like the RVs, the BD5 is so aerodynamically clean that it doesn't slow down very easily. The cruise prop doesn't provide any braking at all! So touchdown at about 90 mph and roll-out takes 2500 - 3000 feet of runway! This is compared to the RV-7 - over the fence at 85 mph, touchdown at ~65 mph, and less than 1000 feet of roll-out.
Due to the take-off and landing roll, the BD5 has to be very particular about the runway lengths it can fly into. If there isn't 5000' available, the pucker factor goes way up!
So, long story short, I'd rather fly my RV-7!
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