Knots 2 U

A place to relax and discuss flying topics.

Moderators: GAHorn, Karl Towle, Bruce Fenstermacher

Knots 2 U

Postby thejetjerk » Mon Dec 21, 2020 11:42 pm

Hi 170 Folks,

I have read everything on the site I can find regarding 170B performance mods. Knots 2U sells a flap gap seal kit for $600 and claims it take about 7 hours to install. They also claim 100-150 FPM rate of climb increase. If this is true it seem like a lot of bang for the buck. Does anyone have any experience with this company or this mod? Do you believe this claim of 100'-150' ? I have seen some opinions here that it may negatively affect flap design, any thoughts on this opinion?

https://www.knots2u.net/cessna-flap-gap ... dels-cfgs/
User avatar
thejetjerk
 
Posts: 4
Joined: Mon Nov 18, 2019 7:09 pm
Location: RCKH

Re: Knots 2 U

Postby Vertical » Tue Dec 22, 2020 1:13 am

They are fantastic. I think it’s more like 250fpm and another 20knots cruise. I have a used set with all the paperwork and plans that I’ll sell you for $200!
Vertical
 
Posts: 78
Joined: Mon Oct 08, 2018 12:41 am

Re: Knots 2 U

Postby Bruce Fenstermacher » Tue Dec 22, 2020 10:55 am

They are so fantastic you see them on every bush plane. And Cessna added this mod later. Oh you don't see it on bush planes and Cessna never added it? Wonder why? I'm seriously just thinking. And I'm thinking the answer is right there.

I don't have any personal experience with them but do understand the aerodynamics of the original design of the flap. I don't believe the mod would do anything for flap performance. I do believe the seal will increase cruise somewhat from decreased drag. How much I don't know but if it was 20 knots cruise, every Cessna would have them. Maybe that was a typo and was suppose to be 2 knots which I'd believe.
CAUTION - My forum posts may be worth what you paid for them!

Bruce Fenstermacher, Past President, TIC170A
Email:
N7A '49 170A -More original than most making folks GREEN with envy
N42532 '45 J-3 Clipped Wing Cub
User avatar
Bruce Fenstermacher
 
Posts: 9815
Joined: Tue Apr 23, 2002 11:24 am
Location: Telford, PA Based at UKT

Re: Knots 2 U

Postby GAHorn » Tue Dec 22, 2020 4:08 pm

Bruce Fenstermacher wrote:They are so fantastic you see them on every bush plane. And Cessna added this mod later. Oh you don't see it on bush planes and Cessna never added it? Wonder why? I'm seriously just thinking. And I'm thinking the answer is right there.

I don't have any personal experience with them but do understand the aerodynamics of the original design of the flap. I don't believe the mod would do anything for flap performance. I do believe the seal will increase cruise somewhat from decreased drag. How much I don't know but if it was 20 knots cruise, every Cessna would have them. Maybe that was a typo and was suppose to be 2 knots which I'd believe.
Attachments
7B8B2487-E9BF-4819-9F06-47A203806E49.png
7B8B2487-E9BF-4819-9F06-47A203806E49.png (2.75 KiB) Viewed 615 times
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight.
An originality nut (mostly) for the right reasons. ;)
User avatar
GAHorn
 
Posts: 19324
Joined: Fri Apr 12, 2002 8:45 pm
Location: Spicewood (Austin), Texas

Re: Knots 2 U

Postby rnealon1 » Tue Dec 22, 2020 4:48 pm

The Knots 2 U listing advertises 3-4 mph cruise speed increase.

Our plane has the B & M seal kit, not sure how it compares. I can't make any direct comparison as it was installed 41 years before our purchase, but I cannot observe any large variations from "book" performance.

I do notice that actual stall speed is way below book, even accounting for lower weight. Like maintaining sustained level flight at 35 mph IAS with full flaps. My technical feeling is that if anything the flap seals would have a negative impact on stall speed, but I am not an aeronautical engineer. In the words of Charlie Ryan, she "just won't stall".

Bob
Bob Nealon

Southbury, CT
User avatar
rnealon1
 
Posts: 138
Joined: Wed Sep 19, 2018 7:28 pm
Location: Southbury, CT

Re: Knots 2 U

Postby thejetjerk » Tue Dec 22, 2020 9:43 pm

Thanks for the responses, I guess that Vertical is joking. I am more interested in better climb performance. Other than a pilot diet I think that for $600 that might be the cheapest mod out there, if it really does give another 100 -150 FPM climb.
User avatar
thejetjerk
 
Posts: 4
Joined: Mon Nov 18, 2019 7:09 pm
Location: RCKH

Re: Knots 2 U

Postby Vertical » Wed Dec 23, 2020 3:53 am

How about $100?

In all seriousness, I might be removing my B&M kit (I think that's the manufacturer). Any member here is welcome to it if you pay for shipping + 1 six pack. I have good paperwork, install instructions drawings etc. It has a 2017 professional white paint job.

I would be interested in any recommendations on how to fill the many empty rivet holes it will leave behind. I don't think there is enough access to buck soft rivets. So maybe pop rivets are the only option?

As to what its benefits may or may not be, I would agree with others that it likely inhibits the flap function, and possibly adds a meager cruise increase. I can't speak to whether or not it would add climb performance. I'm usually trying to go slower, not faster.

If you want to climb faster (in order of expense), go on a diet, carry less fuel, gut the interior to save weight (headliner, PAX seat, back seat, side panels, hat shelf etc), swap for lightweight starter and alternator, buy an 80/40 prop, add a Sportsmans. Or something like that anyways.
Vertical
 
Posts: 78
Joined: Mon Oct 08, 2018 12:41 am

Re: Knots 2 U

Postby cfzxo » Wed Dec 23, 2020 5:22 am

If you want to remove your flap gap seals, the easiest way is to score the seal along the wing skin and leave the rivets in place . I would think that something sharp like and old arborite knife would possibly work. This is not my idea ,but was told to me by the late Dick Lemmon.
User avatar
cfzxo
 
Posts: 126
Joined: Sat Oct 19, 2002 3:29 pm
Location: Terrace BC

Re: Knots 2 U

Postby GAHorn » Wed Dec 23, 2020 11:21 am

Vertical wrote:I would be interested in any recommendations on how to fill the many empty rivet holes it will leave behind. I don't think there is enough access to buck soft rivets. So maybe pop rivets are the only option?.


https://www.aircraftspruce.com/catalog/ ... -00981.php
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight.
An originality nut (mostly) for the right reasons. ;)
User avatar
GAHorn
 
Posts: 19324
Joined: Fri Apr 12, 2002 8:45 pm
Location: Spicewood (Austin), Texas

Re: Knots 2 U

Postby ghostflyer » Wed Dec 23, 2020 11:53 am

It’s my belief that you can’t get something for nothing so putting “aerodynamic aids “ on flaps you will loose something some where . The following is directed at 170A owners only. But due to the flap design where the flap hingers on the lower surface of the wing there is a gap between flap and skin of the lower wing. I tape up this gap spa wise with T-REX tape .[supplied by aero Home Depot.] I can’t really measure the extra performance but have noticed it has affected my cruise speed [positively] when the throttle is opened up. Now looking for pixie dust also.
Last edited by ghostflyer on Thu Dec 24, 2020 3:01 am, edited 1 time in total.
User avatar
ghostflyer
 
Posts: 1132
Joined: Mon Apr 21, 2008 3:06 am
Location: queensland ,australia

Re: Knots 2 U

Postby cessna170bdriver » Wed Dec 23, 2020 4:29 pm

ghostflyer wrote:It’s my belief that you can’t get something for nothing so putting “aerodynamic aids “ on flaps you will loose something some where . The following is directed at 170A owners only. But due to the flap design where the flap hingers on the lower surface of the wing there is a gap between flap and skin of the lower wing. I tape up this gap spa wise with T-REX tape .[supplied by aero Home Depot.] I can’t really measure the extra performance but have noticed it has affected my cruise speed [positively] when the throttles are opened up. Now looking for pixie dust also.


Since you used “throttles” in the plural, I’m guessing the extra performance is coming from the additional engine(s) you have installed. :lol:
Miles
User avatar
cessna170bdriver
 
Posts: 3831
Joined: Mon Apr 22, 2002 5:13 pm
Location: 45G, SE Michigan

Re: Knots 2 U

Postby ghostflyer » Thu Dec 24, 2020 3:03 am

Nah, it was typo or could be the pixie dust .
User avatar
ghostflyer
 
Posts: 1132
Joined: Mon Apr 21, 2008 3:06 am
Location: queensland ,australia


Return to The Pilot Lounge

Who is online

Users browsing this forum: Google [Bot] and 13 guests